AMEREN CORP, 10-K filed on 3/3/2014
Annual Report
Document And Entity Information (USD $)
12 Months Ended
Dec. 31, 2013
Jan. 31, 2014
Jun. 28, 2013
Document Type
10-K 
 
 
Amendment Flag
false 
 
 
Document Period End Date
Dec. 31, 2013 
 
 
Document Fiscal Year Focus
2013 
 
 
Document Fiscal Period Focus
FY 
 
 
Trading Symbol
AEE 
 
 
Entity Registrant Name
AMEREN CORP 
 
 
Entity Central Index Key
0001002910 
 
 
Current Fiscal Year End Date
--12-31 
 
 
Entity Filer Category
Large Accelerated Filer 
 
 
Entity Common Stock, Shares Outstanding
 
242,634,671 
 
Entity Voluntary Filers
No 
 
 
Entity Current Reporting Status
Yes 
 
 
Entity Public Float
 
 
$ 8,356,338,069 
Entity Well-known Seasoned Issuer
Yes 
 
 
Union Electric Company
 
 
 
Document Type
10-K 
 
 
Amendment Flag
false 
 
 
Document Period End Date
Dec. 31, 2013 
 
 
Document Fiscal Year Focus
2013 
 
 
Document Fiscal Period Focus
FY 
 
 
Trading Symbol
AEE 
 
 
Entity Registrant Name
UNION ELECTRIC CO 
 
 
Entity Central Index Key
0000100826 
 
 
Current Fiscal Year End Date
--12-31 
 
 
Entity Filer Category
Non-accelerated Filer 
 
 
Entity Common Stock, Shares Outstanding
 
102,123,834 
 
Entity Voluntary Filers
No 
 
 
Entity Current Reporting Status
Yes 
 
 
Entity Well-known Seasoned Issuer
No 
 
 
Ameren Illinois Company
 
 
 
Document Type
10-K 
 
 
Amendment Flag
false 
 
 
Document Period End Date
Dec. 31, 2013 
 
 
Document Fiscal Year Focus
2013 
 
 
Document Fiscal Period Focus
FY 
 
 
Trading Symbol
AEE 
 
 
Entity Registrant Name
Ameren Illinois Co 
 
 
Entity Central Index Key
0000018654 
 
 
Current Fiscal Year End Date
--12-31 
 
 
Entity Filer Category
Non-accelerated Filer 
 
 
Entity Common Stock, Shares Outstanding
 
25,452,373 
 
Entity Voluntary Filers
No 
 
 
Entity Current Reporting Status
Yes 
 
 
Entity Well-known Seasoned Issuer
No 
 
 
Consolidated Statement Of Income (Loss) (USD $)
Share data in Millions, except Per Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Operating Revenues:
 
 
 
Electric
$ 4,832,000,000 
$ 4,857,000,000 
$ 5,147,000,000 
Gas
1,006,000,000 
924,000,000 
1,001,000,000 
Total operating revenues
5,838,000,000 
5,781,000,000 
6,148,000,000 
Operating Expenses:
 
 
 
Fuel
845,000,000 
714,000,000 
866,000,000 
Purchased power
502,000,000 
780,000,000 
952,000,000 
Gas purchased for resale
526,000,000 
472,000,000 
570,000,000 
Other operations and maintenance
1,617,000,000 
1,511,000,000 
1,562,000,000 
Loss from regulatory disallowance
   
   
89,000,000 
Impairment and other charges
   
   
 
Depreciation and amortization
706,000,000 
673,000,000 
643,000,000 
Taxes other than income taxes
458,000,000 
443,000,000 
433,000,000 
Total operating expenses
4,654,000,000 
4,593,000,000 
5,115,000,000 
Operating Income
1,184,000,000 
1,188,000,000 
1,033,000,000 
Other Income and Expenses:
 
 
 
Miscellaneous income
69,000,000 1
70,000,000 1
68,000,000 1
Miscellaneous expense
26,000,000 1
37,000,000 1
23,000,000 1
Total other income (expense)
43,000,000 
33,000,000 
45,000,000 
Interest charges
398,000,000 
392,000,000 
387,000,000 
Income Before Income Taxes
829,000,000 
829,000,000 
691,000,000 
Income taxes
311,000,000 1
307,000,000 1
254,000,000 1
Income from Continuing Operations
518,000,000 
522,000,000 
437,000,000 
Income (Loss) from Discontinued Operations, Net of Tax (Note 16)
(223,000,000)
(1,496,000,000)
89,000,000 
Net Income (Loss)
295,000,000 
(974,000,000)
526,000,000 
Less: Net Income (Loss) Attributable to Noncontrolling Interests:
 
 
 
Continuing Operations
6,000,000 
6,000,000 
6,000,000 
Discontinued Operations
   
(6,000,000)
1,000,000 
Net Income (Loss):
 
 
 
Net income attributable to Ameren Corporation - continuing operations
512,000,000 
516,000,000 
431,000,000 
Discontinued Operations
(223,000,000)
(1,490,000,000)
88,000,000 
Net income (loss) attributable to Ameren Corporation
289,000,000 
(974,000,000)
519,000,000 
Pension and other postretirement activity, net of income taxes (benefit)
30,000,000 
(8,000,000)
(19,000,000)
Comprehensive Income (Loss)
300,000,000 
(932,000,000)
486,000,000 
Earnings (Loss) per Common Share – Basic:
 
 
 
Continuing Operations - Basic
$ 2.11 
$ 2.13 
$ 1.79 
Discontinued Operations - Basic
$ (0.92)
$ (6.14)
$ 0.36 
Earnings (Loss) per Common Share – Basic
$ 1.19 
$ (4.01)
$ 2.15 
Earnings (Loss) per Common Share – Diluted:
 
 
 
Continuing Operations - Diluted
$ 2.10 
$ 2.13 
$ 1.79 
Discontinued Operations - Diluted
$ (0.92)
$ (6.14)
$ 0.36 
Earnings (Loss) per Common Share – Diluted
$ 1.18 
$ (4.01)
$ 2.15 
Dividends per Common Share
$ 1.60 
$ 1.600 
$ 1.555 
Average Common Shares Outstanding - Basic
242.6 
242.6 
241.5 
Average Common Shares Outstanding - Diluted
244.5 
243.0 
242.1 
Union Electric Company
 
 
 
Operating Revenues:
 
 
 
Electric
3,379,000,000 
3,132,000,000 
3,222,000,000 
Gas
161,000,000 
139,000,000 
156,000,000 
Other
1,000,000 
1,000,000 
5,000,000 
Total operating revenues
3,541,000,000 
3,272,000,000 
3,383,000,000 
Operating Expenses:
 
 
 
Fuel
845,000,000 
714,000,000 
866,000,000 
Purchased power
127,000,000 
78,000,000 
104,000,000 
Gas purchased for resale
78,000,000 
64,000,000 
77,000,000 
Other operations and maintenance
915,000,000 
827,000,000 
934,000,000 
Loss from regulatory disallowance
   
   
89,000,000 
Depreciation and amortization
454,000,000 
440,000,000 
408,000,000 
Taxes other than income taxes
319,000,000 
304,000,000 
296,000,000 
Total operating expenses
2,738,000,000 
2,427,000,000 
2,774,000,000 
Operating Income
803,000,000 
845,000,000 
609,000,000 
Other Income and Expenses:
 
 
 
Miscellaneous income
58,000,000 
63,000,000 
61,000,000 
Miscellaneous expense
11,000,000 
14,000,000 
10,000,000 
Total other income (expense)
47,000,000 
49,000,000 
51,000,000 
Interest charges
210,000,000 
223,000,000 
209,000,000 
Income Before Income Taxes
640,000,000 
671,000,000 
451,000,000 
Income taxes
242,000,000 
252,000,000 
161,000,000 
Net Income (Loss)
398,000,000 
419,000,000 
290,000,000 
Net Income (Loss):
 
 
 
Net income (loss) attributable to Ameren Corporation
398,000,000 
419,000,000 
290,000,000 
Other Comprehensive Income
   
   
   
Comprehensive Income (Loss)
398,000,000 
419,000,000 
290,000,000 
Preferred Stock Dividends
3,000,000 
3,000,000 
3,000,000 
Net Income Available to Common Stockholder
395,000,000 
416,000,000 
287,000,000 
Ameren Illinois Company
 
 
 
Operating Revenues:
 
 
 
Electric
1,461,000,000 
1,739,000,000 
1,940,000,000 
Gas
847,000,000 
786,000,000 
846,000,000 
Other
3,000,000 
   
1,000,000 
Total operating revenues
2,311,000,000 
2,525,000,000 
2,787,000,000 
Operating Expenses:
 
 
 
Purchased power
380,000,000 
705,000,000 
853,000,000 
Gas purchased for resale
448,000,000 
408,000,000 
492,000,000 
Other operations and maintenance
693,000,000 
684,000,000 
640,000,000 
Depreciation and amortization
243,000,000 
221,000,000 
215,000,000 
Taxes other than income taxes
132,000,000 
130,000,000 
129,000,000 
Total operating expenses
1,896,000,000 
2,148,000,000 
2,329,000,000 
Operating Income
415,000,000 
377,000,000 
458,000,000 
Other Income and Expenses:
 
 
 
Miscellaneous income
10,000,000 
7,000,000 
7,000,000 
Miscellaneous expense
9,000,000 
17,000,000 
6,000,000 
Total other income (expense)
1,000,000 
(10,000,000)
1,000,000 
Interest charges
143,000,000 
129,000,000 
136,000,000 
Income Before Income Taxes
273,000,000 
238,000,000 
323,000,000 
Income taxes
110,000,000 
94,000,000 
127,000,000 
Net Income (Loss)
163,000,000 
144,000,000 
196,000,000 
Net Income (Loss):
 
 
 
Net income (loss) attributable to Ameren Corporation
163,000,000 
144,000,000 
196,000,000 
Pension and other postretirement activity, net of income taxes (benefit)
(3,000,000)
(3,000,000)
(3,000,000)
Comprehensive Income (Loss)
160,000,000 
141,000,000 
193,000,000 
Preferred Stock Dividends
3,000,000 
3,000,000 
3,000,000 
Net Income Available to Common Stockholder
$ 160,000,000 
$ 141,000,000 
$ 193,000,000 
Consolidated Statement Of Income (Parenthetical) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Pension and other postretirement activity, tax (benefit)
$ 16 
$ (6)
$ (14)
Ameren Illinois Company
 
 
 
Pension and other postretirement activity, tax (benefit)
$ 2 
$ 2 
$ 2 
Consolidated Statement Of Comprehensive Income (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Income from Continuing Operations
$ 518 
$ 522 
$ 437 
Pension and other postretirement activity, net of income taxes (benefit)
30 
(8)
(19)
Comprehensive Income (Loss) from Continuing Operations
548 
514 
418 
Less: Comprehensive Income from Continuing Operations Attributable to Noncontrolling Interests
6 
6 
6 
Comprehensive Income from Continuing Operations Attributable to Ameren Corporation
542 
508 
412 
Income (Loss) from Discontinued Operations, Net of Tax (Note 16)
(223)
(1,496)
89 
Comprehensive Income from Continuing Operations Attributable to Ameren Corporation
(18)
58 
(20)
Comprehensive Income (Loss) from Discontinued Operations
(241)
(1,438)
69 
Less: Comprehensive Income from Discontinuing Operations Attributable to Noncontrolling Interest
1 
2 
(5)
Comprehensive Income (Loss) from Discontinued Operations Attributable to Ameren Corporation
(242)
(1,440)
74 
Comprehensive Income (Loss)
300 
(932)
486 
Ameren Illinois Company
 
 
 
Pension and other postretirement activity, net of income taxes (benefit)
(3)
(3)
(3)
Comprehensive Income (Loss)
$ 160 
$ 141 
$ 193 
Consolidated Statement Of Comprehensive Income (Parenthetical) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Pension and other postretirement activity, tax (benefit)
$ 16 
$ (6)
$ (14)
Other Comprehensive Income (Loss) from Discontinued Operations Tax (Benefit)
$ (10)
$ 40 
$ (14)
Consolidated Balance Sheet (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Current Assets:
 
 
Cash and cash equivalents
$ 30 
$ 184 
Accounts receivable - trade (less allowance for doubtful accounts)
404 
354 
Unbilled revenue
304 
291 
Miscellaneous accounts and notes receivable
196 
71 
Materials and supplies
526 
570 
Current regulatory assets
156 
247 
Current accumulated deferred income taxes, net
106 
170 
Other current assets
85 
98 
Assets of discontinued operations (Note 16)
165 
1,611 
Total current assets
1,972 
3,596 
Property, Plant and Equipment, Net
16,205 1 2
15,348 1 2
Investments and Other Assets:
 
 
Nuclear decommissioning trust fund
494 
408 
Goodwill
411 
411 
Intangible assets
22 
14 
Regulatory assets
1,240 
1,786 
Other assets
698 
667 
Total investments and other assets
2,865 
3,286 
TOTAL ASSETS
21,042 
22,230 
Current Liabilities:
 
 
Current maturities of long-term debt
534 
355 
Short-term debt
368 
   
Accounts and wages payable
806 
533 
Taxes accrued
55 
49 
Interest accrued
86 
89 
Customer deposits
105 
107 
Mark-to-market derivative liabilities
52 
92 
Current regulatory liabilities
216 
100 
Other current liabilities
194 
168 
Liabilities of discontinued operations (Note 16)
45 
1,193 
Total current liabilities
2,461 
2,686 
Long-term Debt, Net
5,504 
5,802 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
3,166 
3,186 
Accumulated deferred investment tax credits
63 
70 
Regulatory liabilities
1,705 
1,589 
Asset retirement obligations
369 
349 
Pension and other postretirement benefits
466 
1,138 
Other deferred credits and liabilities
622 
643 
Total deferred credits and other liabilities
6,391 
6,975 
Commitments and Contingencies (Notes 2, 10, 14 and 15)
   
   
Stockholders' Equity:
 
 
Common stock
2 
2 
Other paid-in capital, principally premium on common stock
5,632 
5,616 
Preferred stock not subject to mandatory redemption
142 
142 
Retained earnings
907 
1,006 
Accumulated other comprehensive income (loss)
3 
(8)
Total stockholders' equity
6,544 
6,616 
Noncontrolling Interests
142 
151 
Total equity
6,686 
6,767 
TOTAL LIABILITIES AND EQUITY
21,042 
22,230 
Union Electric Company
 
 
Current Assets:
 
 
Cash and cash equivalents
1 
148 
Advances to money pool
   
24 
Accounts receivable - trade (less allowance for doubtful accounts)
191 
161 
Accounts receivable - affiliates
1 
4 
Unbilled revenue
168 
145 
Miscellaneous accounts and notes receivable
57 
48 
Materials and supplies
352 
397 
Current regulatory assets
118 
163 
Current accumulated deferred income taxes, net
20 
26 
Other current assets
71 
69 
Total current assets
959 
1,159 
Property, Plant and Equipment, Net
10,452 1
10,161 1
Investments and Other Assets:
 
 
Nuclear decommissioning trust fund
494 
408 
Intangible assets
22 
14 
Regulatory assets
534 
852 
Other assets
443 
449 
Total investments and other assets
1,493 
1,723 
TOTAL ASSETS
12,904 
13,043 
Current Liabilities:
 
 
Current maturities of long-term debt
109 
205 
Due to Related Parties, Current
105 
   
Accounts and wages payable
387 
345 
Accounts payable - affiliates
30 
66 
Taxes accrued
220 
28 
Interest accrued
57 
60 
Current regulatory liabilities
57 
18 
Other current liabilities
82 
77 
Total current liabilities
1,047 
799 
Long-term Debt, Net
3,648 
3,801 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
2,509 
2,443 
Accumulated deferred investment tax credits
59 
64 
Regulatory liabilities
1,041 
917 
Asset retirement obligations
366 
346 
Pension and other postretirement benefits
189 
461 
Other deferred credits and liabilities
52 
158 
Total deferred credits and other liabilities
4,216 
4,389 
Commitments and Contingencies (Notes 2, 10, 14 and 15)
   
   
Stockholders' Equity:
 
 
Common stock
511 
511 
Other paid-in capital, principally premium on common stock
1,560 
1,556 
Preferred stock not subject to mandatory redemption
80 
80 
Retained earnings
1,842 
1,907 
Total stockholders' equity
3,993 
4,054 
TOTAL LIABILITIES AND EQUITY
12,904 
13,043 
Ameren Illinois Company
 
 
Current Assets:
 
 
Cash and cash equivalents
1 
   
Accounts receivable - trade (less allowance for doubtful accounts)
201 
182 
Accounts receivable - affiliates
   
10 
Unbilled revenue
135 
146 
Miscellaneous accounts and notes receivable
13 
22 
Materials and supplies
174 
173 
Current regulatory assets
38 
84 
Current accumulated deferred income taxes, net
45 
85 
Other current assets
26 
47 
Total current assets
633 
749 
Property, Plant and Equipment, Net
5,589 
5,052 
Investments and Other Assets:
 
 
Intercompany tax receivable – Genco
   
39 
Goodwill
411 
411 
Regulatory assets
701 
934 
Other assets
120 
97 
Total investments and other assets
1,232 
1,481 
TOTAL ASSETS
7,454 
7,282 
Current Liabilities:
 
 
Current maturities of long-term debt
   
150 
Borrowings from money pool
56 
24 
Accounts and wages payable
243 
146 
Accounts payable - affiliates
18 
86 
Taxes accrued
23 
18 
Customer deposits
79 
85 
Mark-to-market derivative liabilities
36 
77 
Environmental remediation
43 
37 
Current regulatory liabilities
159 
82 
Other current liabilities
114 
92 
Total current liabilities
771 
797 
Long-term Debt, Net
1,856 
1,577 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
1,116 
1,025 
Accumulated deferred investment tax credits
4 
5 
Regulatory liabilities
664 
672 
Pension and other postretirement benefits
197 
406 
Accrued Environmental Loss Contingencies, Noncurrent
232 
216 
Other deferred credits and liabilities
166 
183 
Total deferred credits and other liabilities
2,379 
2,507 
Commitments and Contingencies (Notes 2, 10, 14 and 15)
   
   
Stockholders' Equity:
 
 
Common stock
0 
0 
Other paid-in capital, principally premium on common stock
1,965 
1,965 
Preferred stock not subject to mandatory redemption
62 
62 
Retained earnings
410 
360 
Accumulated other comprehensive income (loss)
11 
14 
Total stockholders' equity
2,448 
2,401 
TOTAL LIABILITIES AND EQUITY
$ 7,454 
$ 7,282 
Consolidated Balance Sheet (Parenthetical) (USD $)
In Millions, except Share data, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Accounts receivable - trade, allowance for doubtful accounts
$ 18 
$ 17 
Common stock, par value
$ 0.01 
$ 0.01 
Common stock, shares authorized
400,000,000 
400,000,000 
Common stock, shares outstanding
242,600,000 
242,600,000 
Union Electric Company
 
 
Accounts receivable - trade, allowance for doubtful accounts
5 
5 
Common stock, par value
$ 5 
$ 5 
Common stock, shares authorized
150,000,000 
150,000,000 
Common stock, shares outstanding
102,100,000 
102,100,000 
Ameren Illinois Company
 
 
Accounts receivable - trade, allowance for doubtful accounts
$ 13 
$ 12 
Common Stock, No Par Value
   
   
Common stock, shares authorized
45,000,000 
45,000,000 
Common stock, shares outstanding
25,500,000 
25,500,000 
Consolidated Statement Of Cash Flows (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Cash Flows From Operating Activities:
 
 
 
Net income (loss)
$ 295 
$ (974)
$ 526 
(Income) Loss from discontinued operations, net of tax
223 
1,496 
(89)
Adjustments to reconcile net income to net cash provided by operating activities:
 
 
 
Depreciation and amortization
666 
633 
602 
Amortization of nuclear fuel
71 
83 
61 
Amortization of debt issuance costs and premium/discounts
24 
20 
16 
Deferred income taxes and investment tax credits, net
410 
257 
262 
Allowance for equity funds used during construction
(37)1
(36)1
(34)1
Share-based Compensation
27 
29 
17 
Loss from regulatory disallowance
   
   
89 
Other
23 
(7)
1 
Changes in assets and liabilities:
 
 
 
Receivables
(60)
30 
200 
Materials and supplies
60 
(28)
(29)
Accounts and wages payable
81 
(34)
(28)
Taxes accrued
(195)
(4)
(5)
Assets, other
2 
(6)
59 
Liabilities, other
33 
65 
(85)
Pension and other postretirement benefits
(28)
(23)
(100)
Counterparty collateral, net
41 
41 
36 
Premiums paid on long-term debt repurchases
   
138 
   
Net cash provided by operating activities - continuing operations
1,636 
1,404 
1,499 
Net cash provided by operating activities - discontinued operations
57 
286 
379 
Net cash provided by operating activities
1,693 
1,690 
1,878 
Cash Flows From Investing Activities:
 
 
 
Capital expenditures
(1,379)
(1,063)
(881)
Nuclear fuel expenditures
(45)
(91)
(62)
Purchases of securities - nuclear decommissioning trust fund
(214)
(403)
(220)
Sales and maturities of securities - nuclear decommissioning trust fund
196 
384 
199 
Tax grants received related to renewable energy properties
   
18 
   
Other
2 
2 
15 
Net cash used in investing activities - continuing operations
(1,440)
(1,153)
(949)
Net cash used in investing activities - discontinued operations
(283)
(157)
(99)
Net cash used in investing activities
(1,723)
(1,310)
(1,048)
Cash Flows From Financing Activities:
 
 
 
Dividends on common stock
(388)
(382)
(375)
Dividends paid to noncontrolling interest holders
(6)
(6)
(6)
Short-term debt and credit facility repayments, net
368 
(148)
(481)
Redemptions, repurchases, and maturities:
 
 
 
Long-term debt
(399)
(760)
(155)
Issuances:
 
 
 
Long-term debt
278 
882 
   
Common stock
   
   
65 
Capital issuance costs
(2)
(16)
0 
Advances received for construction
1 
4 
5 
Repayments of advances received for construction
(1)
   
(73)
Net cash provided by (used in) financing activities - continuing operations
(149)
(426)
(1,020)
Net cash provided by (used in) financing activities - discontinued operations
   
   
(100)
Net cash provided by (used in) financing activities
(149)
(426)
(1,120)
Net change in cash and cash equivalents
(179)
(46)
(290)
Cash and cash equivalents at beginning of year
209 
255 
545 
Cash and cash equivalents at end of year
30 
209 
255 
Less: Cash and cash equivalents of discontinued operations at end of year
   
25 
7 
Cash and cash equivalents at beginning of year
184 
248 
 
Cash and cash equivalents at end of year
30 
184 
248 
Noncash financing activity – dividends on common stock
   
7 
   
Cash Paid (Refunded) During the Year:
 
 
 
Interest net of capitalized
393 
433 
453 
Income taxes, net
8 
1 
(61)
Union Electric Company
 
 
 
Cash Flows From Operating Activities:
 
 
 
Net income (loss)
398 
419 
290 
Adjustments to reconcile net income to net cash provided by operating activities:
 
 
 
Depreciation and amortization
419 
407 
377 
Amortization of nuclear fuel
71 
83 
61 
FAC prudence review charge
26 
   
18 
Amortization of debt issuance costs and premium/discounts
7 
6 
6 
Deferred income taxes and investment tax credits, net
65 
287 
155 
Allowance for equity funds used during construction
(31)
(31)
(30)
Loss from regulatory disallowance
   
   
89 
Other
1 
8 
(8)
Changes in assets and liabilities:
 
 
 
Receivables
(59)
27 
66 
Materials and supplies
45 
(48)
(7)
Accounts and wages payable
42 
(27)
12 
Taxes accrued
100 
(46)
(6)
Assets, other
47 
(35)
79 
Liabilities, other
10 
14 
(48)
Pension and other postretirement benefits
2 
2 
2 
Premiums paid on long-term debt repurchases
   
62 
   
Net cash provided by operating activities
1,143 
1,004 
1,056 
Cash Flows From Investing Activities:
 
 
 
Capital expenditures
(648)
(595)
(550)
Nuclear fuel expenditures
(45)
(91)
(62)
Purchases of securities - nuclear decommissioning trust fund
(214)
(403)
(220)
Sales and maturities of securities - nuclear decommissioning trust fund
196 
384 
199 
Money pool advances, net
24 
(24)
   
Tax grants received related to renewable energy properties
   
18 
   
Other
   
8 
6 
Net cash used in investing activities
(687)
(703)
(627)
Cash Flows From Financing Activities:
 
 
 
Dividends on common stock
(460)
(400)
(403)
Dividends on preferred stock
(3)
(3)
(3)
Money pool borrowings, net
105 
   
   
Redemptions, repurchases, and maturities:
 
 
 
Long-term debt
(249)
(427)
(5)
Issuances:
 
 
 
Long-term debt
   
482 
   
Capital issuance costs
   
(7)
   
Capital contribution from parent
4 
1 
   
Repayments of advances received for construction
   
   
(19)
Net cash provided by (used in) financing activities
(603)
(354)
(430)
Net change in cash and cash equivalents
(147)
(53)
(1)
Cash and cash equivalents at beginning of year
148 
201 
202 
Cash and cash equivalents at end of year
1 
148 
201 
Cash Paid (Refunded) During the Year:
 
 
 
Interest net of capitalized
212 
220 
210 
Income taxes, net
86 
(3)
9 
Ameren Illinois Company
 
 
 
Cash Flows From Operating Activities:
 
 
 
Net income (loss)
163 
144 
196 
Adjustments to reconcile net income to net cash provided by operating activities:
 
 
 
Depreciation and amortization
238 
214 
206 
Amortization of debt issuance costs and premium/discounts
15 
11 
8 
Deferred income taxes and investment tax credits, net
104 
104 
155 
Allowance for equity funds used during construction
(6)
(5)
(4)
Other
4 
(11)
(14)
Changes in assets and liabilities:
 
 
 
Receivables
50 
23 
146 
Materials and supplies
15 
20 
(21)
Accounts and wages payable
19 
(21)
(46)
Taxes accrued
28 
3 
(12)
Assets, other
(53)
22 
(3)
Liabilities, other
33 
72 
(30)
Pension and other postretirement benefits
(8)
(26)
(101)
Counterparty collateral, net
43 
40 
20 
Premiums paid on long-term debt repurchases
   
76 
   
Net cash provided by operating activities
651 
519 
504 
Cash Flows From Investing Activities:
 
 
 
Capital expenditures
(701)
(442)
(351)
Returns from (advances to) ATXI for construction
   
   
49 
Other
6 
5 
6 
Net cash used in investing activities
(695)
(437)
(296)
Cash Flows From Financing Activities:
 
 
 
Dividends on common stock
(110)
(189)
(327)
Dividends on preferred stock
(3)
(3)
(3)
Money pool borrowings, net
32 
24 
   
Redemptions, repurchases, and maturities:
 
 
 
Long-term debt
(150)
(333)
(150)
Issuances:
 
 
 
Long-term debt
278 
400 
   
Capital issuance costs
(2)
(6)
   
Capital contribution from parent
   
   
19 
Advances received for construction
1 
4 
5 
Repayments of advances received for construction
(1)
   
(53)
Net cash provided by (used in) financing activities
45 
(103)
(509)
Net change in cash and cash equivalents
1 
(21)
(301)
Cash and cash equivalents at beginning of year
   
21 
322 
Cash and cash equivalents at end of year
1 
   
21 
Cash Paid (Refunded) During the Year:
 
 
 
Interest net of capitalized
112 
125 
137 
Income taxes, net
$ (23)
$ (22)
$ (14)
Consolidated Statement Of Cash Flows (Parenthetical) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Union Electric Company
 
 
 
Capitalized interest
$ 16 
$ 15 
$ 25 
Ameren Illinois Company
 
 
 
Capitalized interest
$ 4 
$ 2 
$ 2 
Consolidated Statement Of Stockholders' Equity (USD $)
In Millions, unless otherwise specified
Total
Common Stock
Other Paid-In Capital
Retained Earnings
Derivative Financial Instruments
Deferred Retirement Benefit Costs
Accumulated Other Comprehensive Income (Loss)
Noncontrolling Interest
Total Ameren Corporation Stockholders' Equity
Union Electric Company
Union Electric Company
Common Stock
Union Electric Company
Other Paid-In Capital
Union Electric Company
Preferred Stock Not Subject To Mandatory Redemption
Union Electric Company
Retained Earnings
Ameren Illinois Company
Ameren Illinois Company
Common Stock
Ameren Illinois Company
Other Paid-In Capital
Ameren Illinois Company
Preferred Stock Not Subject To Mandatory Redemption
Ameren Illinois Company
Retained Earnings
Ameren Illinois Company
Deferred Retirement Benefit Costs
Ameren Illinois Company
Accumulated Other Comprehensive Income (Loss)
Beginning of year at Dec. 31, 2010
 
$ 2 
$ 5,520 
$ 2,225 
$ 0 
$ (17)
 
$ 154 
 
 
 
$ 1,555 
 
$ 2,007 
 
 
$ 1,952 
$ 62 
$ 542 
$ 20 
 
Beginning of year (shares) at Dec. 31, 2010
240.4 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
526 
 
 
 
 
 
 
 
 
290 
 
 
 
290 
196 
 
 
 
196 
 
 
Net income (loss) attributable to Ameren Corporation
519 
 
 
519 
 
 
 
 
 
290 
 
 
 
 
196 
 
 
 
 
 
 
Shares issued (value)
 
 
65 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Shares issued (number of shares)
2.2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Stock-based compensation activity
 
 
13 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Capital contribution from parent
 
 
 
 
 
 
 
 
 
   
 
   
 
 
19 
 
13 
 
 
 
 
Common stock dividends
 
 
 
(375)
 
 
 
 
 
 
 
 
 
(403)
 
 
 
 
(327)
 
 
Preferred stock dividends
 
 
 
 
 
 
 
 
 
 
 
 
 
(3)
 
 
 
 
(3)
 
 
Change in derivative financial instruments
 
 
 
 
7 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Divestiture of derivative financial instruments
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Change in deferred retirement benefit costs
19 
 
 
 
 
(40)
 
 
 
 
 
 
 
 
3 
 
 
 
 
 
(3)
Divestiture of deferred retirement benefit costs
 
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income attributable to noncontrolling interest holder
 
 
 
 
 
 
 
7 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dividends paid to noncontrolling interest holders
 
 
 
 
 
 
 
(6)
 
 
 
 
 
 
 
 
 
 
 
 
 
Divestiture of noncontrolling interest
 
 
 
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
Other
 
 
 
 
 
 
 
(6)
 
 
 
 
 
 
 
 
 
 
 
 
 
Total stockholders' equity
 
 
 
 
 
 
 
 
7,919 
4,037 
 
 
 
 
2,452 
 
 
 
 
 
 
Stockholders' equity, end of year at Dec. 31, 2011
 
 
 
 
 
 
 
 
7,919 
4,037 
 
 
 
 
2,452 
 
 
 
 
 
 
End of year at Dec. 31, 2011
8,068 
2 
5,598 
2,369 
7 
(57)
(50)
149 
 
 
511 
1,555 
80 
1,891 
 
   
1,965 
62 
408 
17 
17 
End of year (shares) at Dec. 31, 2011
242.6 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
(403)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss) attributable to Ameren Corporation
(403)
 
 
 
 
 
 
 
 
22 
 
 
 
 
28 
 
 
 
 
 
 
Stockholders' equity, end of year at Mar. 31, 2012
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Beginning of year at Dec. 31, 2011
8,068 
2 
5,598 
2,369 
7 
(57)
(50)
149 
 
 
511 
1,555 
80 
1,891 
 
   
1,965 
62 
408 
17 
17 
Beginning of year (shares) at Dec. 31, 2011
242.6 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
(974)
 
 
 
 
 
 
 
 
419 
 
 
 
419 
144 
 
 
 
144 
 
 
Net income (loss) attributable to Ameren Corporation
(974)
 
 
(974)
 
 
 
 
 
419 
 
 
 
 
144 
 
 
 
 
 
 
Shares issued (value)
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Shares issued (number of shares)
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Stock-based compensation activity
 
 
18 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Capital contribution from parent
 
 
 
 
 
 
 
 
 
1 
 
1 
 
 
   
 
0 
 
 
 
 
Common stock dividends
 
 
 
(389)
 
 
 
 
 
 
 
 
 
(400)
 
 
 
 
(189)
 
 
Preferred stock dividends
 
 
 
 
 
 
 
 
 
 
 
 
 
(3)
 
 
 
 
(3)
 
 
Change in derivative financial instruments
 
 
 
 
18 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Divestiture of derivative financial instruments
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Change in deferred retirement benefit costs
8 
 
 
 
 
24 
 
 
 
 
 
 
 
 
3 
 
 
 
 
 
(3)
Divestiture of deferred retirement benefit costs
 
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income attributable to noncontrolling interest holder
 
 
 
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dividends paid to noncontrolling interest holders
 
 
 
 
 
 
 
(6)
 
 
 
 
 
 
 
 
 
 
 
 
 
Divestiture of noncontrolling interest
 
 
 
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
Other
 
 
 
 
 
 
 
8 
 
 
 
 
 
 
 
 
 
 
 
 
 
Total stockholders' equity
6,616 
 
 
 
 
 
 
 
6,616 
4,054 
 
 
 
 
2,401 
 
 
 
 
 
 
Stockholders' equity, end of year at Dec. 31, 2012
6,616 
 
 
 
 
 
 
 
6,616 
4,054 
 
 
 
 
2,401 
 
 
 
 
 
 
End of year at Dec. 31, 2012
6,767 
2 
5,616 
1,006 
25 
(33)
(8)
151 
 
 
511 
1,556 
80 
1,907 
 
   
1,965 
62 
360 
14 
14 
End of year (shares) at Dec. 31, 2012
242.6 
 
 
 
 
 
 
 
 
102.1 
 
 
 
 
25.5 
 
 
 
 
 
 
Beginning of year at Sep. 30, 2012
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
(1,155)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss) attributable to Ameren Corporation
(1,156)
 
 
 
 
 
 
 
 
16 
 
 
 
 
12 
 
 
 
 
 
 
Total stockholders' equity
6,616 
 
 
 
 
 
 
 
6,616 
4,054 
 
 
 
 
2,401 
 
 
 
 
 
 
Stockholders' equity, end of year at Dec. 31, 2012
6,616 
 
 
 
 
 
 
 
6,616 
4,054 
 
 
 
 
2,401 
 
 
 
 
 
 
End of year at Dec. 31, 2012
6,767 
2 
 
 
 
 
(8)
 
 
 
511 
 
80 
 
 
   
 
62 
 
14 
 
End of year (shares) at Dec. 31, 2012
242.6 
 
 
 
 
 
 
 
 
102.1 
 
 
 
 
25.5 
 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
(143)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss) attributable to Ameren Corporation
(145)
 
 
 
 
 
 
 
 
41 
 
 
 
 
32 
 
 
 
 
 
 
Stockholders' equity, end of year at Mar. 31, 2013
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Beginning of year at Dec. 31, 2012
6,767 
2 
5,616 
1,006 
25 
(33)
(8)
151 
 
 
511 
1,556 
80 
1,907 
 
   
1,965 
62 
360 
14 
14 
Beginning of year (shares) at Dec. 31, 2012
242.6 
 
 
 
 
 
 
 
 
102.1 
 
 
 
 
25.5 
 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
295 
 
 
 
 
 
 
 
 
398 
 
 
 
398 
163 
 
 
 
163 
 
 
Net income (loss) attributable to Ameren Corporation
289 
 
 
289 
 
 
 
 
 
398 
 
 
 
 
163 
 
 
 
 
 
 
Shares issued (value)
 
 
   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Shares issued (number of shares)
   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Stock-based compensation activity
 
 
16 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Capital contribution from parent
 
 
 
 
 
 
 
 
 
4 
 
4 
 
 
   
 
   
 
 
 
 
Common stock dividends
 
 
 
(388)
 
 
 
 
 
 
 
 
 
(460)
 
 
 
 
(110)
 
 
Preferred stock dividends
 
 
 
 
 
 
 
 
 
 
 
 
 
(3)
 
 
 
 
(3)
 
 
Change in derivative financial instruments
 
 
 
 
(21)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Divestiture of derivative financial instruments
 
 
 
 
(4)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Change in deferred retirement benefit costs
(30)
 
 
 
 
29 
 
 
 
 
 
 
 
 
3 
 
 
 
 
 
(3)
Divestiture of deferred retirement benefit costs
 
 
 
 
 
7 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income attributable to noncontrolling interest holder
 
 
 
 
 
 
 
6 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dividends paid to noncontrolling interest holders
 
 
 
 
 
 
 
(6)
 
 
 
 
 
 
 
 
 
 
 
 
 
Divestiture of noncontrolling interest
 
 
 
 
 
 
 
9 
 
 
 
 
 
 
 
 
 
 
 
 
 
Other
 
 
 
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
Total stockholders' equity
6,544 
 
 
 
 
 
 
 
6,544 
3,993 
 
 
 
 
2,448 
 
 
 
 
 
 
Stockholders' equity, end of year at Dec. 31, 2013
6,544 
 
 
 
 
 
 
 
6,544 
3,993 
 
 
 
 
2,448 
 
 
 
 
 
 
End of year at Dec. 31, 2013
6,686 
2 
5,632 
907 
0 
3 
3 
142 
 
 
511 
1,560 
80 
1,842 
 
   
1,965 
 
410 
11 
11 
End of year (shares) at Dec. 31, 2013
242.6 
 
 
 
 
 
 
 
 
102.1 
 
 
 
 
25.5 
 
 
 
 
 
 
Beginning of year at Sep. 30, 2013
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
38 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss) attributable to Ameren Corporation
37 
 
 
 
 
 
 
 
 
33 
 
 
 
 
22 
 
 
 
 
 
 
Total stockholders' equity
6,544 
 
 
 
 
 
 
 
6,544 
3,993 
 
 
 
 
2,448 
 
 
 
 
 
 
Stockholders' equity, end of year at Dec. 31, 2013
6,544 
 
 
 
 
 
 
 
6,544 
3,993 
 
 
 
 
2,448 
 
 
 
 
 
 
End of year at Dec. 31, 2013
$ 6,686 
$ 2 
 
 
 
 
$ 3 
 
 
 
$ 511 
 
$ 80 
 
 
    
 
 
 
$ 11 
 
End of year (shares) at Dec. 31, 2013
242.6 
 
 
 
 
 
 
 
 
102.1 
 
 
 
 
25.5 
 
 
 
 
 
 
Summary Of Significant Accounting Policies
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
General
Ameren, headquartered in St. Louis, Missouri, is a public utility holding company under PUHCA 2005, administered by FERC. Ameren’s primary assets are its equity interests in its subsidiaries. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of other expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below.
•
Union Electric Company, doing business as Ameren Missouri, operates a rate-regulated electric generation, transmission, and distribution business, and a rate-regulated natural gas transmission and distribution business in Missouri. Ameren Missouri was incorporated in Missouri in 1922 and is successor to a number of companies, the oldest of which was organized in 1881. It is the largest electric utility in the state of Missouri. It supplies electric and natural gas service to a 24,000-square-mile area in central and eastern Missouri. This area has an estimated population of 2.8 million and includes the Greater St. Louis area. Ameren Missouri supplies electric service to 1.2 million customers and natural gas service to 127,000 customers.
•
Ameren Illinois Company, doing business as Ameren Illinois, operates a rate-regulated electric and natural gas transmission and distribution business in Illinois. Ameren Illinois was created by the merger of CILCO and IP with and into CIPS in 2010. CIPS was incorporated in Illinois in 1923 and is the successor to a number of companies, the oldest of which was organized in 1902. Ameren Illinois supplies electric and natural gas utility service to portions of central and southern Illinois having an estimated population of 3.1 million in an area of 40,000 square miles. Ameren Illinois supplies electric service to 1.2 million customers and natural gas service to 767,000 customers.
Ameren has various other subsidiaries responsible for activities such as the provision of shared services. Ameren also has a subsidiary, ATXI, that operates a FERC rate-regulated electric transmission business and is developing the Illinois Rivers project.
On March 14, 2013, Ameren entered into a transaction agreement to divest New AER to IPH. On December 2, 2013, Ameren completed the divestiture of New AER to IPH. On January 31, 2014, Medina Valley completed its sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital. See Note 16 – Divestiture Transactions and Discontinued Operations for additional information.
As a result of the transaction agreement with IPH and Ameren’s plan to sell its Elgin, Gibson City, and Grand Tower gas-fired energy centers, Ameren determined that New AER and the gas-fired energy centers qualified for discontinued operations presentation beginning March 14, 2013. In addition, as of December 2, 2013, Ameren abandoned the Meredosia and Hutsonville energy centers upon the completion of the divestiture of New AER to IPH. Ameren is prohibited from operating these energy centers through December 31, 2020, as a provision of the Illinois Pollution Control Board's November 2013 order granting IPH a variance of the MPS. As a result, Ameren determined that the Meredosia and Hutsonville energy centers qualified for discontinued operations presentation as of December 2, 2013. The Meredosia and Hutsonville energy centers ceased operations at December 31, 2011, and therefore 2011 was the last year those energy centers had a material effect on Ameren's consolidated financial statements. As a result of these events, Ameren has segregated New AER’s and the Elgin, Gibson City, Grand Tower, Meredosia, and Hutsonville energy centers’ operating results, assets, and liabilities and presented them separately as discontinued operations for all periods presented in this report. Unless otherwise stated, these notes to the financial statements exclude discontinued operations for all periods presented. See Note 16 – Divestiture Transactions and Discontinued Operations for additional information regarding that presentation.
The financial statements of Ameren are prepared on a consolidated basis, and therefore include the accounts of its majority-owned subsidiaries. Ameren Missouri and Ameren Illinois have no subsidiaries and therefore their financial statements are not prepared on a consolidated basis. All significant intercompany transactions have been eliminated. All tabular dollar amounts are in millions, unless otherwise indicated.
Our accounting policies conform to GAAP. Our financial statements reflect all adjustments (which include normal, recurring adjustments) that are necessary, in our opinion, for a fair presentation of our results. The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. Such estimates and assumptions affect reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of financial statements, and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates.
Regulation
Certain Ameren subsidiaries are regulated by the MoPSC, the ICC, and FERC. In accordance with authoritative accounting guidance regarding accounting for the effects of certain types of regulation, Ameren Missouri and Ameren Illinois defer certain costs as assets pursuant to actions of rate regulators or because of expectations that the companies will be able to recover such costs in rates charged to customers. Ameren Missouri and Ameren Illinois also defer certain amounts as liabilities pursuant to actions of rate regulators or based on the expectation that such amounts will be returned to customers in future rates. Regulatory assets and liabilities are amortized consistent with the period of expected regulatory treatment. In addition to the cost recovery mechanisms discussed in the Purchased Gas, Power and Fuel Rate-adjustment Mechanisms section below, Ameren Missouri and Ameren Illinois have approvals from regulators to use other cost recovery mechanisms. Ameren Missouri has a vegetation management and infrastructure inspection cost tracker, a pension and postretirement benefit cost tracker, an uncertain tax positions tracker, a renewable energy standards cost tracker, a storm restoration cost tracker, and the MEEIA energy efficiency rider. In addition to participating in the IEIMA's formula rate regulatory framework, Ameren Illinois has an environmental cost rider, an asbestos-related litigation rider, an energy efficiency rider, and a bad debt rider. See Note 2 – Rate and Regulatory Matters for additional information on regulatory assets and liabilities. In addition, other costs that Ameren Missouri and Ameren Illinois expect to recover from customers are recorded as construction work in progress and property and plant, net. See Note 3 – Property and Plant, Net.
Cash and Cash Equivalents
Cash and cash equivalents include cash on hand and temporary investments purchased with an original maturity of three months or less.
Allowance for Doubtful Accounts Receivable
The allowance for doubtful accounts represents our estimate of existing accounts receivable that will ultimately be uncollectible. The allowance is calculated by applying estimated loss factors to various classes of outstanding receivables, including unbilled revenue. The loss factors used to estimate uncollectible accounts are based upon both historical collections experience and management’s estimate of future collections success given the existing and anticipated future collections environment. Ameren Illinois has a rate mechanism that adjusts rates for net write-offs of customer accounts receivable above or below those being collected in rates.
Materials and Supplies
Materials and supplies are recorded at the lower of cost or market. Cost is determined using the average-cost method. Materials and supplies are capitalized as inventory when purchased and then expensed or capitalized as plant assets when installed, as appropriate. The following table presents a breakdown of materials and supplies for each of the Ameren Companies at December 31, 2013, and 2012:
 
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2013
 
 
 
 
 
 
Fuel(a)
 
$
144

 
$
—

 
$
144

Gas stored underground
 
17

 
110

 
127

Other materials and supplies
 
191

 
64

 
255

 
 
$
352

 
$
174

 
$
526

2012
 
 
 
 
 
 
Fuel(a)
 
$
198

 
$
—

 
$
198

Gas stored underground
 
18

 
113

 
131

Other materials and supplies
 
181

 
60

 
241

 
 
$
397

 
$
173

 
$
570

(a)
Consists of coal, oil, and propane.

Property and Plant
We capitalize the cost of additions to and betterments of units of property and plant. The cost includes labor, material, applicable taxes, and overhead. An allowance for funds used during construction, as discussed below, is also capitalized as a cost of our rate-regulated assets. Maintenance expenditures, including nuclear refueling and maintenance outages, are expensed as incurred. When units of depreciable property are retired, the original costs, less salvage values, are charged to accumulated depreciation. Asset removal costs accrued by our rate-regulated operations that do not constitute legal obligations are classified as a regulatory liability. See Asset Retirement Obligations below and Note 3 – Property and Plant, Net, for additional information.
Depreciation
Depreciation is provided over the estimated lives of the various classes of depreciable property by applying composite rates on a straight-line basis to the cost basis of such property. The provision for depreciation for the Ameren Companies in 2013, 2012 and 2011 ranged from 3% to 4% of the average depreciable cost.
Allowance for Funds Used During Construction
We capitalize allowance for funds used during construction, or the cost of borrowed funds and the cost of equity funds (preferred and common stockholders’ equity) applicable to rate-regulated construction expenditures, in accordance with the utility industry's accounting practice. Allowance for funds used during construction does not represent a current source of cash funds. This accounting practice offsets the effect on earnings of the cost of financing during construction, and it treats such financing costs in the same manner as construction charges for labor and materials.
Under accepted ratemaking practice, cash recovery of allowance for funds used during construction and other construction costs occurs when completed projects are placed in service and reflected in customer rates. The following table presents the annual allowance for funds used during construction rates that were utilized during 2013, 2012 and 2011:
 
2013
 
2012
 
2011
Ameren Missouri
8
%
 
8
%
 
8
%
Ameren Illinois
8
%
 
9
%
 
9
%

Goodwill and Intangible Assets
Goodwill. Goodwill represents the excess of the purchase price of an acquisition over the fair value of the net assets acquired. Ameren and Ameren Illinois had recorded goodwill of $411 million at December 31, 2013, and 2012.
Ameren has two reporting units, which also represent Ameren’s reportable segments. Ameren's reporting units are Ameren Missouri and Ameren Illinois. Ameren Illinois has one reporting unit, Ameren Illinois. Ameren’s and Ameren Illinois' reporting units have been defined and goodwill has been evaluated at the operating segment level in accordance with authoritative accounting guidance. Our reporting units represent businesses for which discrete financial information is available and reviewed regularly by management. All of Ameren's and Ameren Illinois' goodwill at December 31, 2013, and 2012, has been assigned to the Ameren Illinois reporting unit.
We evaluate goodwill for impairment as of October 31 of each year, or more frequently if events and circumstances indicate that the asset might be impaired. Ameren and Ameren Illinois applied a qualitative goodwill evaluation model for their annual goodwill impairment test conducted as of October 31, 2013. Based on the results of Ameren’s and Ameren Illinois’ qualitative assessment, Ameren and Ameren Illinois believe it was more likely than not that the fair value of the Ameren Illinois reporting unit exceeded its carrying value as of October 31, 2013, indicating no impairment of Ameren’s or Ameren Illinois’ goodwill. The following factors, among others, were considered by Ameren and Ameren Illinois when assessing whether it was more likely than not that the fair value of the Ameren Illinois reporting unit exceeded its carrying value for the October 31, 2013, test:
•
macroeconomic conditions, including those conditions within Ameren Illinois’ service territory;
•
pending rate case outcomes and projections of future rate case outcomes;
•
changes in laws and potential law changes;
•
observable industry market multiples;
•
achievement of IEIMA performance metrics and the yield of the 30-year United States treasury bonds; and
•
actual and forecasted financial performance.
The goodwill assigned to the Ameren Illinois reporting unit on the December 31, 2013, balance sheets of Ameren and Ameren Illinois had no accumulated goodwill impairment losses. Ameren and Ameren Illinois will continue to monitor the actual and forecasted operating results, cash flows, market capitalization, and observable industry market multiples of the Ameren Illinois reporting unit for signs of possible declines in estimated fair value and potential goodwill impairment.
Intangible Assets. Ameren and Ameren Missouri classify emission allowances and renewable energy credits as intangible assets. Ameren Illinois consumes renewable energy credits as they are purchased through the IPA procurement process and expenses them immediately. We evaluate intangible assets for impairment if events or changes in circumstances indicate that their carrying amount might be impaired.
At December 31, 2013, Ameren’s and Ameren Missouri’s intangible assets consisted of renewable energy credits obtained through wind and solar power purchase agreements. The book value of Ameren’s and Ameren Missouri’s renewable energy credits was $22 million and $22 million at December 31, 2013, respectively. The book value of Ameren's and Ameren Missouri's renewable energy credits was $14 million and $14 million at December 31, 2012, respectively.
Renewable energy credits and emission allowances are charged to purchased power expense and fuel expense, respectively, as they are used in operations. In accordance with the MoPSC's 2012 electric rate order, most of Ameren Missouri's amortization of intangible assets is deferred as a regulatory asset pending future recovery from customers through rates. The following table presents amortization expense based on usage of renewable energy credits and emission allowances, net of gains from sales, for Ameren, Ameren Missouri, and Ameren Illinois during the years ended December 31, 2013, 2012, and 2011.
 
 
2013
 
2012
 
2011
Ameren Missouri
$
(a)

$
(a)

$
(a)

Ameren Illinois
 
13

 
4

 
3

Ameren
$
13

$
4

$
3

(a)
Less than $1 million.
Impairment of Long-lived Assets
We evaluate long-lived assets classified as held and used for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. Whether impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets with the carrying value of the assets. If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount of the carrying value that exceeds the estimated fair value of the assets. In the period in which we determine an asset meets held for sale criteria, we record an impairment charge to the extent the book value exceeds its fair value less cost to sell.
During 2011, the MoPSC issued an electric rate order that disallowed the recovery of all costs of enhancements, or costs that would have been incurred absent the breach, related to the rebuilding of the Taum Sauk energy center in excess of the amount recovered from property insurance. Consequently, Ameren and Ameren Missouri each recorded a pretax charge to earnings of $89 million, which is reflected as "Taum Sauk regulatory disallowance" on each company's statement of income.
Investments
Ameren and Ameren Missouri evaluate for impairment the investments held in Ameren Missouri’s nuclear decommissioning trust fund. Losses on assets in the trust fund could result in higher funding requirements for decommissioning costs, which Ameren Missouri believes would be recovered in electric rates paid by its customers. Accordingly, Ameren and Ameren Missouri recognize a regulatory asset on their balance sheets for losses on investments held in the nuclear decommissioning trust fund. See Note 9 – Nuclear Decommissioning Trust Fund Investments for additional information.
Environmental Costs
Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are expensed or deferred as a regulatory asset when it is expected that the costs will be recovered from customers in future rates. If environmental expenditures are related to facilities currently in use, such as pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset.
Unamortized Debt Discount, Premium, and Expense
Discount, premium, and expense associated with long-term debt are amortized over the lives of the related issues.
Revenue
Operating Revenues
The Ameren Companies record operating revenue for electric or natural gas service when it is delivered to customers. We accrue an estimate of electric and natural gas revenues for service rendered but unbilled at the end of each accounting period.
Beginning in 2012, Ameren Illinois elected to participate in the performance-based formula ratemaking framework pursuant to the IEIMA. The IEIMA provides for an annual reconciliation of Ameren Illinois' electric distribution revenue requirement. As of each balance sheet date, Ameren Illinois records its estimate of the electric distribution revenue impact resulting from the reconciliation of the revenue requirement necessary to reflect the actual costs incurred for that year with the revenue requirement that was in effect for billing purposes for that year. If the current year's revenue requirement is greater than the revenue requirement customer rates were based upon, an increase to electric operating revenues with an offset to a regulatory asset is recorded to reflect the expected recovery of those additional costs from customers within the next two years. If the current year's revenue requirement is less than the revenue requirement customer rates were based upon, a reduction to electric operating revenues with an offset to a regulatory liability is recorded to reflect the expected refund to customers within the next two years. See Note 2 – Rate and Regulatory Matters for information regarding Ameren Illinois' revenue requirement reconciliation pursuant to the IEIMA.
Similar to the IEIMA process described above, Ameren Illinois and ATXI record the impact of a revenue requirement reconciliation for each company's electric transmission jurisdiction, pursuant to FERC-approved rate treatment.
Nuclear Fuel
Ameren Missouri’s cost of nuclear fuel is capitalized and then amortized to fuel expense on a unit-of-production basis. Spent fuel disposal cost is based on net kilowatthours generated and sold. That cost is charged to "Operating Expenses – Fuel" in the statement of income.
Purchased Gas, Power and Fuel Rate-adjustment Mechanisms
Ameren Missouri and Ameren Illinois have various rate-adjustment mechanisms in place that provide for the recovery of purchased natural gas and electric fuel and purchased power costs. See Note 2 – Rate and Regulatory Matters for the regulatory assets and liabilities recorded at December 31, 2013, and 2012, related to the rate-adjustment mechanisms discussed below.
In Ameren Missouri’s and Ameren Illinois’ retail natural gas utility jurisdictions, changes in natural gas costs are reflected in billings to their natural gas utility customers through PGA clauses. The differences between actual natural gas costs and costs billed to customers in a given period are deferred as regulatory assets or liabilities. The deferred amounts are either billed or refunded to natural gas utility customers in a subsequent period.
In Ameren Illinois’ retail electric utility jurisdictions, changes in purchased power and transmission service costs are reflected in billings to their electric utility customers through pass-through rate-adjustment clauses. The differences between actual purchased power and transmission service costs and costs billed to customers in a given period are deferred as regulatory assets or liabilities. The deferred amounts are either billed or refunded to electric utility customers in a subsequent period.
Ameren Missouri has a FAC that allows an adjustment of electric rates three times per year for a pass-through to customers of 95% of changes in fuel, certain fuel additives, emission allowances, purchased power costs, transmission costs and revenues, and MISO costs and revenues, net of off-system sales revenues, greater or less than the amount set in base rates without a traditional rate proceeding, subject to MoPSC prudency review. The differences between the cost of fuel incurred and the cost of fuel recovered from Ameren Missouri customers' base rates are deferred as regulatory assets or liabilities. The deferred amounts are either billed or refunded to Ameren Missouri’s electric utility customers in a subsequent period.
Accounting for MISO Transactions
MISO-related purchase and sale transactions are recorded by Ameren, Ameren Missouri and Ameren Illinois using settlement information provided by MISO. Ameren Missouri records these purchase and sale transactions on a net hourly position. Ameren Missouri records net purchases in a single hour in “Operating Expenses - Purchased power” and net sales in a single hour in “Operating Revenues - Electric” in its statement of income. Ameren Illinois records net purchases in “Operating Expenses - Purchased Power” in its statement of income to reflect all of its MISO transactions relating to the procurement of power for its customers. On occasion, Ameren Missouri and Ameren Illinois prior-period transactions will be resettled outside the routine settlement process because of a change in MISO’s tariff or a material interpretation thereof. In these cases, Ameren Missouri and Ameren Illinois recognize expenses associated with resettlements once the resettlement is probable and the resettlement amount can be estimated, and the Ameren Companies recognize revenues once the resettlement amount is received.
Stock-based Compensation
Stock-based compensation cost is measured at the grant date based on the fair value of the award. Ameren recognizes as compensation expense the estimated fair value of stock-based compensation on a straight-line basis over the requisite service period. See Note 12 – Stock-based Compensation for additional information.
Excise Taxes
Excise taxes levied on us are reflected on Ameren Missouri electric customer bills and on Ameren Missouri and Ameren Illinois natural gas customer bills. They are recorded gross in “Operating Revenues – Electric,” “Operating Revenues – Gas” and “Operating Expenses – Taxes other than income taxes” on the statement of income (loss). Excise taxes reflected on Ameren Illinois electric customer bills are imposed on the customer and are therefore not included in revenues and expenses. They are included in “Taxes accrued” on the balance sheet. The following table presents excise taxes recorded in “Operating Revenues – Electric,” “Operating Revenues – Gas,” and “Operating Expenses – Taxes other than income taxes” for the years ended 2013, 2012 and 2011:
 
2013
 
2012
 
2011
Ameren Missouri
$
152

 
$
139

 
$
137

Ameren Illinois
61

 
54

 
57

Ameren
$
213

 
$
193

 
$
194


Income Taxes
Ameren uses an asset and liability approach for its financial accounting and reporting of income taxes, in accordance with authoritative accounting guidance. Deferred tax assets and liabilities are recognized for transactions that are treated differently for financial reporting and income tax return purposes. These deferred tax assets and liabilities are based on statutory tax rates.
We recognize that regulators will probably reduce future revenues for deferred tax liabilities that were initially recorded at rates in excess of the current statutory rate. Therefore, reductions in the deferred tax liability, which were recorded because of decreases in the statutory rate, have been credited to a regulatory liability. A regulatory asset has been established to recognize the probable recovery in rates of future income taxes, resulting from the reversal of the equity portion of the allowance for funds used during construction that was an unrecognized temporary difference prior to the adoption of the authoritative accounting guidance for income taxes.
Investment tax credits used on tax returns for prior years have been deferred in accordance with GAAP. The credits are being amortized over the useful lives of the related investment. Deferred income taxes were recorded on the temporary difference represented by the deferred investment tax credits and a corresponding regulatory liability. This recognizes the expected reduction in rate revenue for future lower income taxes associated with the amortization of the investment tax credits. See Note 13 – Income Taxes.
For certain renewable energy construction projects placed in service, Ameren Missouri elected to seek federal tax grants in lieu of the investment tax credits for which the projects also qualified. These grants were accounted for using a grant recognition accounting model. Ameren Missouri elected to reduce the basis of property as grants were received, which will reduce the amount of depreciation expense recognized in future periods. In 2012, Ameren Missouri received $18 million in federal tax grants.
Ameren Missouri, Ameren Illinois, and all the other Ameren subsidiary companies are parties to a tax allocation agreement with Ameren that provides for the allocation of consolidated tax liabilities. The tax allocation agreement specifies that each party be allocated an amount of tax similar to that which would be owed had the party been separately subject to tax. Any net benefit attributable to the parent is reallocated to other members. That allocation is treated as a contribution of capital to the party receiving the benefit.
Noncontrolling Interests
As of December 31, 2013, Ameren’s noncontrolling interests included the preferred stock not subject to mandatory redemption of Ameren Missouri and Ameren Illinois. As of December 31, 2012, Ameren's noncontrolling interests also included the 20% of EEI not owned by Ameren. All noncontrolling interests are classified as a component of equity separate from Ameren’s equity in its consolidated balance sheet.
Earnings per Share
Basic earnings per share is computed by dividing net income attributable to Ameren Corporation by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed by dividing net income attributable to Ameren Corporation by the diluted weighted-average number of common shares outstanding during the period. Diluted earnings per share reflects the potential dilution that would occur if certain stock-based performance share units were settled.
The following table presents Ameren’s basic and diluted earnings per share calculations and reconciles the weighted-average number of common shares outstanding to the diluted weighted-average number of common shares outstanding for the years ended December 31, 2013, 2012 and 2011:
 
2013
 
2012
 
2011
Net income (loss) attributable to Ameren Corporation:
 
 
 
 
 
Continuing operations
$
512

 
$
516

 
$
431

Discontinued operations
(223
)
 
(1,490
)
 
88

Net income (loss) attributable to Ameren Corporation
$
289

 
$
(974
)
 
$
519

 
 
 
 
 
 
Average common shares outstanding – basic
242.6

 
242.6

 
241.5

Assumed settlement of performance share units
1.9

 
0.4

 
0.6

Average common shares outstanding – diluted
244.5

 
243.0

 
242.1

 
 
 
 
 
 
Earnings (loss) per common share – basic:
 
 
 
 
 
Continuing operations
$
2.11

 
$
2.13

 
$
1.79

Discontinued operations
(0.92
)
 
(6.14
)
 
0.36

Earnings (loss) per common share – basic
$
1.19

 
$
(4.01
)
 
$
2.15

 
 
 
 
 
 
Earnings (loss) per common share – diluted:
 
 
 
 
 
Continuing operations
$
2.10

 
$
2.13

 
$
1.79

Discontinued operations
(0.92
)
 
(6.14
)
 
0.36

Earnings (loss) per common share – diluted
$
1.18

 
$
(4.01
)
 
$
2.15

 
 
 
 
 
 
Average performance share units excluded from calculation(a)
0.1

 
0.7

 
—

(a)
Weighted-average number of performance share units that were excluded from the “Assumed settlement of performance share units” provided above because the performance or market conditions related to the awards had not yet been met.
Supplemental Cash Flow Information
The following table presents additional information regarding Ameren's consolidated statement of cash flows for the years ended December 31, 2013, 2012 and 2011:
 
2013
 
2012
 
2011
Cash paid (refunded) during the year:

 
 
 
 
 
Interest
 
 
 
 
 
Continuing operations(a)
$
362

 
$
384

 
$
393

Discontinued operations(b)
31

 
49

 
60

 
$
393

 
$
433

 
$
453

 
 
 
 
 
 
Income taxes, net
 
 
 
 
 
Continuing Operations
$
116

 
$
10

 
$
(47
)
Discontinued Operations
(108
)
 
(9
)
 
(14
)
 
$
8

 
$
1

 
$
(61
)
(a)
Net of $20 million, $17 million, and $27 million capitalized, respectively.
(b)
Net of $17 million, $13 million, and $3 million capitalized, respectively.
See Note 3 – Property and Plant, Net, for information on accrued capital expenditures.
Accounting Changes and Other Matters
The following is a summary of recently adopted authoritative accounting guidance, as well as guidance issued but not yet adopted, that could affect the Ameren Companies.
Presentation of Comprehensive Income
In June 2011, FASB amended its guidance on the presentation of comprehensive income in financial statements. The amended guidance changed the presentation of comprehensive income in the financial statements. It requires entities to report components of comprehensive income either in a continuous statement of comprehensive income or in two separate but consecutive statements. This guidance was effective for the Ameren Companies beginning in the first quarter of 2012 with retroactive application required. The implementation of the amended guidance did not affect the Ameren Companies’ results of operations, financial position, or liquidity.
In February 2013, FASB amended this guidance to require an entity to provide information about the amounts reclassified out of accumulated OCI by component. In addition, an entity is required to present significant amounts reclassified out of accumulated OCI by the respective line items of net income either on the face of the statement where net income is presented or in the footnotes. This guidance was effective for the Ameren Companies beginning in the first quarter of 2013. The implementation of this amended guidance did not affect the Ameren Companies’ results of operations, financial position, or liquidity. The amounts reclassified out of accumulated OCI for the Ameren Companies corresponding to continuing operations related to pension and other postretirement plan activity. These amounts were immaterial for the year ended December 31, 2013, and therefore no additional disclosures were required.
Disclosures about Offsetting Assets and Liabilities
In December 2011, FASB issued additional authoritative accounting guidance to improve information disclosed about financial and derivative instruments. The guidance requires an entity to disclose information about offsetting and related arrangements to enable users of the financial statements to understand the effect of those arrangements on its financial position. In January 2013, FASB amended this guidance to limit the scope to derivative instruments, repurchase agreements and reverse repurchase agreements, and securities borrowing and securities lending transactions. The Ameren Companies adopted this guidance for the first quarter of 2013. The implementation of this additional guidance did not affect the Ameren Companies’ results of operations, financial positions, or liquidity, as this guidance only requires additional disclosures. See Note 7 – Derivative Financial Instruments for the required additional disclosures.
Presentation of an Unrecognized Tax Benefit
In July 2013, FASB issued additional authoritative accounting guidance to provide clarity for the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. It requires entities to present an unrecognized tax benefit as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward to the extent a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is available under the tax law. Currently, any unrecognized tax benefit is recorded in “Other deferred credits and liabilities” on Ameren's, Ameren Missouri's, and Ameren Illinois' balance sheets. After this guidance becomes effective, any unrecognized tax benefit will be recorded in “Accumulated deferred income taxes, net” as a reduction to the deferred tax assets for net operating loss, a similar tax loss, and tax credit carryforwards on the respective balance sheets. At December 31, 2013, unrecognized tax benefits of $48 million and $15 million would have been recorded in “Accumulated deferred income taxes, net” at Ameren and Ameren Missouri, respectively under this new guidance. To the extent that an unrecognized tax benefit exceeds these carryforwards, the excess would continue to be recorded in “Other deferred credits and liabilities” on the respective balance sheets, consistent with current authoritative accounting guidance. The amended guidance will not affect the Ameren Companies' results of operations or liquidity, as this guidance is presentation-related only. This guidance will be effective for the Ameren Companies beginning in the first quarter of 2014.
Asset Retirement Obligations
Authoritative accounting guidance requires us to record the estimated fair value of legal obligations associated with the retirement of tangible long-lived assets in the period in which the liabilities are incurred and to capitalize a corresponding amount as part of the book value of the related long-lived asset. In subsequent periods, we are required to make adjustments to AROs based on changes in the estimated fair values of the obligations. Corresponding increases in asset book values are depreciated over the remaining useful life of the related asset. Uncertainties as to the probability, timing, or amount of cash flows associated with AROs affect our estimates of fair value. Ameren and Ameren Missouri have recorded AROs for retirement costs associated with Ameren Missouri’s Callaway energy center decommissioning costs, asbestos removal, CCR storage facilities, and river structures. Also, Ameren and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal. In addition, Ameren, Ameren Missouri and Ameren Illinois have recorded AROs for the disposal of certain transformers.
Asset removal costs accrued by our rate-regulated operations that do not constitute legal obligations are classified as a regulatory liability. See Note 2 – Rate and Regulatory Matters.

The following table provides a reconciliation of the beginning and ending carrying amount of AROs for the years ended December 31, 2013, and 2012:
 
Ameren
Missouri(a)
 
Ameren
Illinois(b)
 
Ameren(a)
 
Balance at December 31, 2011
$
328

 
$
3

 
$
331

 
Liabilities incurred
—

 
—

 
—

 
Liabilities settled
(1
)
 
(c)

 
(1
)
 
Accretion in 2012(d)
18

 
(c)

 
18

 
Change in estimates(e)
1

 
(c)

 
1

 
Balance at December 31, 2012
$
346

 
$
3

 
$
349

 
Liabilities incurred
—

 
—

 
—

 
Liabilities settled
(1
)
 
(c)

 
(1
)
 
Accretion in 2013(d)
19

 
(c)

 
19

 
Change in estimates(e)
2

 
(c)

 
2

 
Balance at December 31, 2013
$
366

 
$
3

 
$
369

 
(a)
The nuclear decommissioning trust fund assets of $494 million and $408 million as of December 31, 2013, and 2012, respectively, are restricted for decommissioning of the Callaway energy center.
(b)
Balance included in “Other deferred credits and liabilities” on the balance sheet.
(c)
Less than $1 million.
(d)
Accretion expense was recorded as an increase to regulatory assets at Ameren Missouri and Ameren Illinois.
(e)
Ameren Missouri changed its fair value estimates for asbestos removal in 2012 and 2013, and for certain CCR storage facilities in 2013.                    
See Note 16 – Divestiture Transactions and Discontinued Operations for additional information on the AROs related to the abandoned Meredosia and Hutsonville energy centers, which are presented as discontinued operations and therefore not included in the table above.

Employee Separation Charges
During the fourth quarter of 2011, Ameren Missouri and Ameren Services extended voluntary separation offers consistent with Ameren’s standard management separation program to eligible management and labor union-represented employees. Approximately 340 employees of Ameren Missouri and Ameren Services accepted the offers and left their employment by December 31, 2011. Ameren and Ameren Missouri recorded a pretax charge to earnings of $28 million and $27 million, respectively, for the severance costs related to these offers. These charges were recorded in “Other operations and maintenance" expense in each company’s statement of income for the year ended December 31, 2011. Substantially all of the severance costs were paid in the first quarter of 2012. The severance costs related to participating Ameren Services employees were allocated to affiliates consistent with the terms of its support services agreement, which is described in Note 14 – Related Party Transactions.
Rate And Regulatory Matters
RATE AND REGULATORY MATTERS
RATE AND REGULATORY MATTERS
Below is a summary of significant regulatory proceedings and related lawsuits. We are unable to predict the ultimate outcome of these matters, the timing of the final decisions of the various agencies and courts, or the impact on our results of operations, financial position, or liquidity.
Missouri
FAC Prudence Review
In April 2011, the MoPSC issued an order with respect to its review of Ameren Missouri's FAC for the period from March 1, 2009, to September 30, 2009. In this order, the MoPSC ruled that Ameren Missouri should have included in the FAC calculation all revenues and costs associated with certain long-term partial requirements sales that were made by Ameren Missouri because of the loss of Noranda's load caused by a severe ice storm in January 2009. As a result of the order, Ameren Missouri recorded a pretax charge to earnings of $18 million, including $1 million for interest, in 2011 for its obligation to refund to its electric customers the earnings associated with these sales previously recognized by Ameren Missouri during the period from March 1, 2009, to September 30, 2009. In May 2012, upon appeal by Ameren Missouri, the Cole County Circuit Court reversed the MoPSC's April 2011 order. In June 2012, the MoPSC and a group of large industrial customers filed an appeal of the Cole County Circuit Court's ruling to the Missouri Court of Appeals, Western District. In May 2013, the Missouri Court of Appeals upheld the MoPSC’s April 2011 order and reversed the Cole County Circuit Court’s May 2012 decision.
Ameren Missouri’s FAC calculation for the period from October 1, 2009, to May 31, 2011, excluded all revenues and costs associated with certain long-term partial requirements sales that were made by Ameren Missouri because of the loss of Noranda’s load caused by a severe ice storm in January 2009, similar to the FAC calculation for the period from March 1, 2009, to September 30, 2009. The MoPSC issued an order in July 2013, which was similar to the MoPSC's April 2011 order, as a result of which Ameren Missouri recorded a pretax charge to earnings of $26 million, including $1 million for interest, in 2013 for its estimated obligation to refund to Ameren Missouri’s electric customers the earnings associated with these sales previously recognized by Ameren Missouri for the period from October 1, 2009, to May 31, 2011. Ameren Missouri recorded the charge to “Operating Revenues – Electric” and the related interest to “Interest Charges” with a corresponding offset to “Current regulatory liabilities.” No similar revenues were excluded from FAC calculations after May 2011.
Separately, in July 2011, Ameren Missouri filed a request with the MoPSC for an accounting authority order that would allow Ameren Missouri to defer fixed costs totaling $36 million that were not previously recovered from Noranda as a result of the loss of load caused by the severe 2009 ice storm for potential recovery in a future electric rate case. In November 2013, the MoPSC issued an order approving Ameren Missouri's request for an accounting authority order. Ameren Missouri will seek to recover these fixed costs in its next electric rate case. In February 2014, MIEC filed an appeal of the accounting authority order to the Missouri Court of Appeals, Western District.
2012 Electric Rate Order
In December 2012, the MoPSC issued an order approving an increase for Ameren Missouri in annual revenues for electric service of $260 million. The revenue increase was based on a 9.8% return on equity, a capital structure composed of 52.3% common equity, and a rate base of $6.8 billion. Rate changes consistent with the order became effective on January 2, 2013. In January 2013, Ameren Missouri appealed the order with respect to the amount of property taxes included in the order to the Missouri Court of Appeals, Western District. Later in 2013, Ameren Missouri withdrew this appeal. In February 2013, the MoOPC, MIEC, and other parties filed separate appeals to the Missouri Court of Appeals, Western District, relating to the order's treatment of transmission costs in the FAC. In October 2013, the Missouri Court of Appeals, Western District, upheld the order. MoOPC, MIEC, and other parties filed a request to transfer their appeal to the Missouri Supreme Court, which was subsequently denied.
MEEIA Order
The MoPSC's December 2012 electric rate order approved Ameren Missouri's implementation of MEEIA megawatthour savings targets, energy efficiency programs, and associated cost recovery mechanisms and incentive awards. A MEEIA rider allows Ameren Missouri to collect from or refund to customers any annual difference in the actual amounts incurred and the projected amounts collected from customers for the MEEIA program costs and its projected lost revenues.
In addition to the program costs and lost revenues discussed above, the terms of Ameren Missouri's MoPSC-approved MEEIA programs offer an incentive award that would allow Ameren Missouri to earn additional revenues by achieving certain energy efficiency goals, including approximately $19 million if 100% of its energy efficiency goals are achieved during the three-year period, with the potential to earn more if Ameren Missouri's energy savings exceed those goals. Ameren Missouri must achieve at least 70% of its energy efficiency goals before it earns any incentive award. The recovery of an incentive award from customers, if the energy efficiency goals are achieved, is expected in 2017 through the above-mentioned rider.
Rate Design and Earnings Complaint Cases
On February 13, 2014, Ameren Missouri’s largest customer, Noranda, and 37 residential customers filed an earnings complaint case and a rate design complaint case with the MoPSC. In the earnings complaint case, Noranda and the residential customers asserted that Ameren Missouri’s electric delivery service business is earning more than the 9.8% return on equity authorized in the MoPSC's December 2012 electric rate order and requested the MoPSC to approve a reduction of the authorized return on equity to 9.4%. The rate design complaint case seeks to reduce Noranda’s electricity cost with an offsetting increase in electricity cost for Ameren Missouri’s other customers. The rate design complaint case asks the MoPSC to expedite its decision and grant relief by August 1, 2014.
The MoPSC has ordered Ameren Missouri to file a response to these two complaints by March 17, 2014. The MoPSC has no time requirement by which it must issue an order in these cases. Ameren Missouri opposes both requests filed by Noranda and the residential customers and will vigorously defend itself.
Illinois
IEIMA
Under the provisions of the IEIMA, Ameren Illinois' electric delivery service rates effective for customers' billings in 2013 were subject to an annual revenue requirement reconciliation to its actual 2013 costs. The 2013 revenue requirement reconciliation will be filed with the ICC in 2014. The approved annual revenue requirement reconciliation adjustment relating to 2013 will be reflected in customer rates beginning in January 2015. Throughout the year, Ameren Illinois records a regulatory asset or a regulatory liability and a corresponding increase or decrease to operating revenues for any differences between the revenue requirement in effect for that year and its estimate of the probable increase or decrease in the revenue requirement expected to ultimately be approved by the ICC based on that year's actual costs incurred. As of December 31, 2013, Ameren Illinois recorded a $65 million regulatory asset to reflect its expected 2013 revenue requirement reconciliation adjustment, which will be recovered from customers in 2015. Ameren Illinois also recorded a regulatory liability of $65 million and $55 million as of December 31, 2013, and December 31, 2012, respectively, to reflect its 2012 revenue requirement reconciliation adjustment, with interest, which will be refunded to customers in 2014.
In May 2013, Illinois enacted into law certain amendments to the IEIMA that modified its implementation. The law clarified that the IEIMA requires that the year-end rate base must be used to calculate the revenue requirement reconciliation and that the interest applied to the revenue requirement reconciliation and return on equity collar adjustments must be equal to a company's weighted-average return calculated under the formula rate.
In September 2012, the ICC issued an order in Ameren Illinois' initial filing under the IEIMA's performance-based formula rate framework, which Ameren Illinois appealed to the Appellate Court of the Fourth District of Illinois. In December 2012, the ICC issued an order in Ameren Illinois' update filing approving an Ameren Illinois electric delivery service revenue requirement of $765 million, based on 2011 recoverable costs and expected net plant additions in 2012. The delivery service rates became effective on January 1, 2013. In January 2013, Ameren Illinois filed an appeal of the ICC's update filing order to the Appellate Court of the Fourth District of Illinois. Both orders were consolidated for appeal with the primary issues being the treatment of accumulated deferred income taxes and vacation obligations as well as the calculation of Ameren Illinois' capital structure. In December 2013, the appellate court rendered its decision upholding the ICC's September and December 2012 orders. Ameren Illinois expects to file an appeal to the Illinois Supreme Court in March 2014.
In December 2013, the ICC issued an order in Ameren Illinois' annual update filing, which was based on 2012 recoverable costs and expected net plant additions for 2013, approving an Ameren Illinois electric delivery service revenue requirement of $788 million, before consideration of the 2012 revenue requirement reconciliation refund. The ICC order resulted in a net $45 million decrease in Ameren Illinois' electric delivery service revenue requirement. The calculation included a refund to customers of the 2012 revenue requirement reconciliation of $68 million, which included an estimate for interest through the end of 2014. However, this refund is partially offset by an annual revenue requirement increase of $23 million primarily due to higher recoverable costs in 2012 compared to 2011. The ICC order establishes rates for all of 2014. In January 2014, Ameren Illinois filed a request for rehearing with the ICC regarding the electric delivery service rate order, which the ICC denied. In February 2014, Ameren Illinois filed an appeal with the Appellate Court of the Fourth District of Illinois regarding the calculation of its capital structure and the treatment of accumulated deferred income taxes related to the transfer of former Ameren Missouri assets in Illinois to Ameren Illinois.
In the December 2013 order, the ICC disallowed, in part, the recovery from customers of the debt premium costs paid by Ameren Illinois for a tender offer in August 2012 to repurchase outstanding senior secured notes. At the time of the tender offer, Ameren Illinois recorded this loss on the reacquired debt as a regulatory asset. As a result of the ICC order, Ameren and Ameren Illinois each recorded in 2013 a pretax charge to earnings of $15 million relating to the partial disallowance of the premium costs. This charge was recorded in the statement of income for Ameren and Ameren Illinois as “Interest charges” with a corresponding decrease to “Regulatory assets.”
2013 Natural Gas Delivery Service Rate Order
In December 2013, the ICC issued a rate order that approved an increase in revenues for natural gas delivery service of $32 million. The revenue increase was based on a 9.1% return on equity, a capital structure composed of 51.7% common equity, and a rate base of $1.1 billion. The rate order was based on a 2014 future test year. The rate changes became effective January 1, 2014. In January 2014, Ameren Illinois filed a request for rehearing with the ICC regarding the natural gas delivery service rate order, which the ICC denied. Ameren Illinois expects to file an appeal of the ICC's order in March 2014.
Similar to the December 2013 electric rate order discussed above, this natural gas rate order included a partial disallowance relating to the August 2012 costs for the tender offer to repurchase outstanding senior secured notes. The pretax loss of $15 million discussed above includes the impact of both the December 2013 ICC electric and natural gas delivery service rate orders.
Natural Gas Consumer, Safety and Reliability Act
In July 2013, Illinois enacted the Natural Gas Consumer, Safety and Reliability Act, which encourages Illinois natural gas utilities to accelerate modernization of the state’s natural gas infrastructure and provides additional ICC oversight of natural gas utility performance. The law allows natural gas utilities the option to file for, and requires the ICC to approve, a rate rider mechanism to recover costs of certain natural gas infrastructure investments made between rate cases. The law does not require a minimum level of investment. Ameren Illinois expects to begin including investments under this regulatory framework in 2015. Ameren Illinois' decision to accelerate modernization of its natural gas infrastructure under this regulatory framework is dependent upon multiple considerations, including the allowed return on equity under this framework compared with other Ameren and Ameren Illinois investment options.
ATXI Transmission Project
ATXI's Illinois Rivers project is a MISO-approved project to build a 345-kilovolt line from western Indiana across the state of Illinois to eastern Missouri at an estimated cost of $1.1 billion. In August 2013, the ICC granted a certificate of public convenience and necessity and approved seven of a total of nine sections of the route and three of the proposed nine substations for the Illinois Rivers project. The ICC order indicated the project is necessary to address transmission and reliability needs in an efficient and equitable manner and that the project will benefit the development of a competitive electricity market. The order also indicated that ATXI is capable of constructing, managing and financing the project. In October 2013, the ICC granted ATXI's request for a rehearing to consider additional evidence regarding the two segments of the route and six substations that were not approved, as well as the requests for rehearing of certain other parties regarding two of the approved segments of the route. In February 2014, the ICC issued a final order on rehearing approving the remaining substations and routes for the Illinois Rivers project.
Federal
2011 Wholesale Distribution Rate Case
In January 2011, Ameren Illinois filed a request with FERC to increase its annual revenues for electric delivery service for its wholesale customers. These wholesale distribution revenues are treated as a deduction from Ameren Illinois' revenue requirement in retail rate filings with the ICC. In March 2011, FERC issued an order authorizing the proposed rates to take effect, subject to refund when the final rates are determined. Ameren Illinois reached an agreement with four of its nine wholesale customers. FERC has approved these settlement agreements, and any refund obligations related thereto have been made. The impasse with the remaining five wholesale customers has resulted in FERC litigation. In November 2012, a FERC administrative law judge issued an initial decision, which is now pending before FERC. The timing of a FERC decision is uncertain. In accordance with the administrative law judge's initial decision, Ameren and Ameren Illinois have both included on their balance sheets in "Current regulatory liabilities" an estimate of $13 million and $8 million as of December 31, 2013, and December 31, 2012, respectively, for the refund due to wholesale customers relating to billings for the period from March 2011 through December 2013.
Ameren Illinois Electric Transmission Rate Refund
In July 2012, FERC issued an order concluding that Ameren Illinois improperly included acquisition premiums, primarily goodwill, in determining the common equity used in its electric transmission formula rate, and thereby inappropriately recovered a higher amount from its electric transmission customers. The order required Ameren Illinois to make refunds to customers for such improperly included amounts. In August 2012, Ameren Illinois filed a request for a rehearing of this order. It is unknown when FERC will rule on Ameren's rehearing request, as it is under no deadline to do so.
Ameren Illinois submitted a refund report in November 2012 and concluded that no refund was warranted. Several wholesale customers filed a protest with FERC regarding Ameren's conclusion that no refund was warranted. In June 2013, FERC issued an order that rejected Ameren Illinois' November 2012 refund report and provided guidance as to the filing of a new refund report. In July 2013, Ameren Illinois filed a revised refund report based on the guidance provided in the June 2013 order, as well as a request for a rehearing of that order. Ameren Illinois' July 2013 refund report also concluded that no refund was warranted. Ameren Illinois estimated the maximum pretax charge to earnings for this possible refund obligation through December 31, 2013, would be $15 million, before interest charges. If Ameren Illinois were to determine that a refund to its electric transmission customers is probable, a charge to earnings would be recorded for the refund in the period in which that determination was made.
FERC Complaint Case
In November 2013, a customer group filed a complaint case with FERC seeking a reduction in the allowed return on common equity, as well as a limit on the common equity ratio, under the MISO tariff. Currently, the FERC-allowed return on common equity for MISO transmission owners is 12.38%. This complaint case could result in a reduction to Ameren Illinois' and ATXI's allowed return on common equity. That reduction could also result in a refund for transmission service revenues earned after the filing of the complaint case in November 2013. FERC has not issued an order in this case, and it is under no deadline to do so. Ameren is not able to predict when or how FERC will rule on this complaint case.
Ameren Missouri Power Purchase Agreement with Entergy
Beginning in 2005, FERC issued a series of orders addressing a complaint filed in 2001 by the Louisiana Public Service Commission (LPSC) against Entergy and certain of its affiliates. The complaint alleged unjust and unreasonable cost allocations. As a result of the FERC orders, Entergy began billing Ameren Missouri in 2007 for additional charges under a 165-megawatt power purchase agreement, which expired August 31, 2009. In May 2012, FERC issued an order stating that Entergy should not have included additional charges to Ameren Missouri under the power purchase agreement. Pursuant to the order, in June 2012, Entergy paid Ameren Missouri $31 million, with $24 million recorded as a reduction to “Purchased power” expense and $5 million for interest recorded as “Miscellaneous income” in the statement of income. The remaining $2 million was recorded as an offset to the FAC under-recovered regulatory asset for the amount refundable to customers. The amount of the Entergy refund recorded to the FAC regulatory asset related to the period when the FAC was effective; therefore, such costs were previously included in customer rates. In July 2012, Entergy filed an appeal of FERC's January 2010 and May 2012 orders to the United States Court of Appeals for the District of Columbia Circuit, which was subsequently dismissed on a procedural issue. In November 2013, Entergy refiled the appeal of FERC's May 2012 order with the United States Court of Appeals for the District of Columbia Circuit. Ameren is not able to predict when or how the court will rule on Entergy's appeal.
The LPSC appealed FERC’s orders regarding LPSC’s complaint against Entergy Services, Inc. to the United States Court of Appeals for the District of Columbia Circuit. In April 2008, that court ordered further FERC proceedings regarding LPSC’s complaint. The court ordered FERC to explain its previous denial of retroactive refunds and the implementation of prospective charges. FERC’s decision on remand of the retroactive impact of these issues could have a financial impact on Ameren Missouri. Ameren Missouri is unable to predict when or how FERC will respond to the court’s decisions. Ameren Missouri estimates that it could incur an additional expense of up to $25 million if FERC orders retroactive application for the years 2001 to 2005. Ameren Missouri believes that the likelihood of incurring any expense is not probable, and therefore no liability has been recorded as of December 31, 2013.
Combined Construction and Operating License
In 2008, Ameren Missouri filed an application with the NRC for a COL for a new nuclear unit at Ameren Missouri's existing Callaway County, Missouri, energy center site. In 2009, Ameren Missouri suspended its efforts to build a new nuclear unit at its existing Missouri nuclear energy center site, and the NRC suspended review of the COL application.
In March 2012, the DOE announced the availability of investment funds for the design, engineering, manufacturing, and sale of American-made small modular nuclear reactors. In April 2012, Ameren Missouri entered into an exclusive agreement to support Westinghouse's application for the first installment of DOE's small modular nuclear reactor investment funds. The DOE investment funding is intended to support engineering and design certifications and a COL for up to two small modular reactor designs over five years. A COL is issued by the NRC to permit construction and operation of a nuclear energy center at a specific site in accordance with established laws and regulations. Obtaining a COL from the NRC would not obligate Ameren Missouri to build a small modular reactor at the Callaway site; however, it would preserve the option to move forward in a timely fashion should conditions be right to build a small modular reactor in the future. A COL is valid for at least 40 years. In November 2012, the DOE awarded the first installment of investment funds for only one small modular reactor design, which was not the Westinghouse design. The DOE stated that a second installment of investment funds would be awarded during 2013. In December 2013, the DOE did not award Westinghouse the second installment of investment funds. Ameren Missouri's agreement to exclusively support Westinghouse's application expired in January 2014.
Ameren Missouri estimated the total cost that would be required to obtain the small modular reactor COL to be $80 million to $100 million. As of December 31, 2013, Ameren Missouri had capitalized investments of $69 million for the development of a new nuclear energy center. Ameren is currently evaluating all potential nuclear technologies in order to maintain an option for nuclear power in the future.
All of Ameren Missouri's capitalized investments for the development of a new nuclear energy center will remain capitalized while management pursues options to maximize the value of its investment. If efforts to license additional nuclear generation are abandoned or management concludes it is probable the costs incurred will be disallowed in rates, a charge to earnings would be recognized in the period in which that determination is made.
Pumped-storage Hydroelectric Energy Center Relicensing
In June 2008, Ameren Missouri filed a relicensing application with FERC to operate its Taum Sauk pumped-storage hydroelectric energy center for another 40 years. The existing FERC license expired on June 30, 2010. In July 2010, Ameren Missouri received a license extension that allows Taum Sauk to continue operations until FERC issues a new license. A FERC order is expected in 2014. Ameren Missouri cannot predict the ultimate outcome of FERC's review of the application.
Regulatory Assets and Liabilities

In accordance with authoritative accounting guidance regarding accounting for the effects of certain types of regulation, Ameren Missouri and Ameren Illinois defer certain costs as regulatory assets pursuant to actions of regulators or based on the expected ability to recover such costs in rates charged to customers. Ameren Missouri and Ameren Illinois also defer certain amounts as regulatory liabilities because of actions of regulators or because of the expectation that such amounts will be returned to customers in future rates. The following table presents Ameren’s, Ameren Missouri’s and Ameren Illinois’ regulatory assets and regulatory liabilities at December 31, 2013, and 2012:
 
 
2013
 
2012
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Current regulatory assets:
 
 
 
 
 
 
 
 
 
 
 
 
 
Under-recovered FAC(a)(b)
 
$
104

 
$
—

 
$
104

 
 
$
145

 
$
—

 
$
145

Under-recovered Illinois electric power costs(c)
 
—

 
1

 
1

 
 
—

 
—

 
—

Under-recovered PGA(c)
 
—

 
1

 
1

 
 
5

 
7

 
12

MTM derivative losses(d)
 
14


36

 
50

 
 
13

 
77

 
90

Total current regulatory assets
 
$
118

 
$
38

 
$
156

 
 
$
163

 
$
84

 
$
247

Noncurrent regulatory assets:
 
 
 
 
 
 
 
 
 
 
 
 
 
Pension and postretirement benefit costs(e)
 
$
44

 
$
140

 
$
184

 
 
$
348

 
$
424

 
$
772

Income taxes(f)
 
230

 
7

 
237

 
 
231

 
4

 
235

Asset retirement obligations(g)
 
—

 
5

 
5

 
 
—

 
5

 
5

Callaway costs(a)(h)
 
40

 
—

 
40

 
 
44

 
—

 
44

Unamortized loss on reacquired debt(a)(i)
 
77

 
74

 
151

 
 
81

 
100

 
181

Recoverable costs – contaminated facilities(j)
 
—

 
271

 
271

 
 
—

 
248

 
248

MTM derivative losses(d)
 
8


118

 
126



7

 
128

 
135

Storm costs(k)
 
5

 
3

 
8

 
 
9

 
—

 
9

Demand-side costs before MEEIA implementation(a)(l)
 
58

 
—

 
58

 
 
73

 
—

 
73

Reserve for workers’ compensation liabilities(m)
 
6

 
6

 
12

 
 
6

 
6

 
12

Credit facilities fees(n)
 
5

 
—

 
5

 
 
6

 
—

 
6

Common stock issuance costs(o)
 
4

 
—

 
4

 
 
7

 
—

 
7

Construction accounting for pollution control equipment(a)(p)
 
22

 
—

 
22

 
 
23

 
—

 
23

Solar rebate program(a)(q)
 
27

 
—

 
27

 
 
5

 
—

 
5

IEIMA revenue requirement reconciliation(r)
 
—

 
65

 
65

 
 
—

 
—

 
—

Other(s)(t)
 
8

 
12

 
25

 
 
12

 
19

 
31

Total noncurrent regulatory assets
 
$
534

 
$
701

 
$
1,240

 
 
$
852

 
$
934

 
$
1,786

Current regulatory liabilities:
 
 
 
 
 
 
 
 
 
 
 
 
 
Over-recovered FAC(b)
 
$
26

 
$
—

 
$
26

 
 
$
—

 
$
—

 
$
—

Over-recovered Illinois electric power costs(c)
 
—

 
51

 
51

 
 
—

 
58

 
58

Over-recovered PGA(c)
 
5

 
29

 
34

 
 
—

 
15

 
15

MTM derivative gains(d)
 
26

 
1

 
27


 
18

 
1

 
19

Wholesale distribution refund(u)
 
—

 
13

 
13

 
 
—

 
8

 
8

IEIMA revenue requirement reconciliation(r)
 
—

 
65

 
65

 
 
—

 
—

 
—

Total current regulatory liabilities
 
$
57

 
$
159

 
$
216

 
 
$
18

 
$
82

 
$
100

Noncurrent regulatory liabilities:
 
 
 
 
 
 
 
 
 
 
 
 
 
Income taxes(v)
 
$
38

 
$
3

 
$
41

 
 
$
42

 
$
4

 
$
46

Removal costs(w)
 
828

 
610

 
1,438

 
 
766

 
581

 
1,347

Asset retirement obligation(g)
 
146

 
—

 
146

 
 
80

 
—

 
80

MTM derivative gains(d)
 
1

 
—

 
1


 
2

 
—

 
2

Bad debt riders(x)
 
—

 
8

 
8

 
 
—

 
12

 
12

Pension and postretirement benefit costs tracker(y)
 
15

 
—

 
15

 
 
23

 
—

 
23

Energy efficiency riders(z)
 
3

 
33

 
36

 
 
—

 
20

 
20

IEIMA revenue requirement reconciliation(r)
 
—

 
—

 
—

 
 
—

 
55

 
55

FERC transmission revenue requirement reconciliation(aa)
 
—

 
10

 
10

 
 
—

 
—

 
—

Other(ab)
 
10

 
—

 
10

 
 
4

 
—

 
4

Total noncurrent regulatory liabilities
 
$
1,041

 
$
664

 
$
1,705

 
 
$
917

 
$
672

 
$
1,589

(a)
These assets earn a return.
(b)
Under-recovered or over-recovered fuel costs to be recovered through the FAC. Specific accumulation periods aggregate the under-recovered or over-recovered costs over four months, any related adjustments that occur over the following four months, and the recovery from customers that occurs over the next eight months.
(c)
Costs under- or over-recovered from utility customers. Amounts will be recovered from, or refunded to, customers within one year of the deferral.
(d)
Deferral of commodity-related derivative MTM losses or gains. See Note 7 – Derivative Financial Instruments for additional information.
(e)
These costs are being amortized in proportion to the recognition of prior service costs (credits), transition obligations (assets), and actuarial losses (gains) attributable to Ameren’s pension plan and postretirement benefit plans. See Note 11 – Retirement Benefits for additional information.
(f)
Offset to certain deferred tax liabilities for expected recovery of future income taxes when paid. This will be recovered over the expected life of the related assets.
(g)
Recoverable or refundable removal costs for AROs, including net realized and unrealized gains and losses related to the nuclear decommissioning trust fund investments. See Note 1 – Summary of Significant Accounting Policies – Asset Retirement Obligations.
(h)
Ameren Missouri’s Callaway energy center operations and maintenance expenses, property taxes, and carrying costs incurred between the plant in-service date and the date the plant was reflected in rates. These costs are being amortized over the remaining life of the energy center's current operating license, which expires in 2024.
(i)
Losses related to reacquired debt. These amounts are being amortized over the lives of the related new debt issuances or the original lives of the old debt issuances if no new debt was issued.
(j)
The recoverable portion of accrued environmental site liabilities that will be collected from electric and natural gas customers through ICC-approved cost recovery riders. The period of recovery will depend on the timing of remediation expenditures. See Note 15 – Commitments and Contingencies for additional information.
(k)
Actual storm costs in a test year that exceed the MoPSC staff’s normalized storm costs for rate purposes. As approved by the December 2012 MoPSC electric rate order, the 2006, 2007, and 2008 storm costs are being amortized through December 2014. As approved by the May 2010 MoPSC electric rate order, the 2009 storm costs are being amortized through June 2015. The Ameren Illinois total includes 2013 storm costs deferred in accordance with the IEIMA. These costs are being amortized over a five-year period beginning in 2013.
(l)
Demand-side costs incurred prior to implementation of the MEEIA in 2013, including the costs of developing, implementing and evaluating customer energy efficiency and demand response programs. Costs incurred from May 2008 through September 2008 are being amortized over a 10-year period that began in March 2009. Costs incurred from October 2008 through December 2009 are being amortized over a six-year period that began in July 2010. Costs incurred from January 2010 through February 2011 are being amortized over a six-year period that began in August 2011. Costs incurred from March 2011 through July 2012 are being amortized over a six-year period that began in January 2013.
(m)
Reserve for workers’ compensation claims. The period of recovery will depend on the timing of actual expenditures.
(n)
Ameren Missouri’s costs incurred to enter into and maintain the 2012 Ameren Missouri Credit Agreement. These costs are being amortized over five years, beginning in November 2012. These costs are being amortized to construction work in progress, which will be depreciated when assets are placed into service.
(o)
The MoPSC’s May 2010 electric rate order allowed Ameren Missouri to recover its portion of Ameren’s September 2009 common stock issuance costs. These costs are being amortized over five years, beginning in July 2010.
(p)
The MoPSC’s May 2010 electric rate order allowed Ameren Missouri to record an allowance for funds used during construction for pollution control equipment at its Sioux energy center until the cost of that equipment could be included in customer rates. These costs will be amortized over the expected life of the Sioux energy center, which is currently through 2033.
(q)
Costs associated with Ameren Missouri's solar rebate program beginning in August 2012 to fulfill Ameren Missouri's renewable energy portfolio requirement. The amortization period for these costs will be three years, commencing with the next Ameren Missouri electric rate case order.
(r)
The asset balance relates to the difference between Ameren Illinois' 2013 revenue requirement calculated under the IEIMA's performance-based formula ratemaking framework, and the revenue requirement included in customer rates for 2013. Subject to ICC approval, this asset will be collected from customers in 2015. The liability balance relates to the difference between Ameren Illinois' 2012 revenue requirement calculated under the IEIMA's performance-based formula ratemaking framework and the revenue requirement included in customer rates for 2012. This liability will be refunded to customers in 2014.
(s)
The Ameren Illinois total includes Ameren Illinois Merger integration and optimization costs, which are amortized over four years, beginning in January 2012. The Ameren Illinois total also includes costs related to the 2013 natural gas delivery service rate case costs, which are being amortized over a two-year period that began in January 2014. The Ameren Illinois total also includes a portion of the unamortized debt fair value adjustment recorded upon Ameren's acquisition of IP. This portion is being amortized over the remaining life of the related debt. At Ameren Missouri, the balance primarily includes the cost of renewable energy credits to fulfill its renewable energy portfolio requirement. Costs incurred from January 2010 through July 2012 are being amortized over three years, beginning in January 2013.
(t)
The Ameren total includes $5 million for ATXI's revenue requirement reconciliation adjustments for 2012 and 2013 calculated pursuant to the FERC's electric transmission formula ratemaking framework. These adjustments will be collected from customers in 2014 for the 2012 revenue requirement reconciliation and in 2015 for the 2013 revenue requirement reconciliation.
(u)
Estimated refund to wholesale electric customers. See 2011 Wholesale Distribution Rate Case above.
(v)
Unamortized portion of investment tax credits, federal excess deferred taxes, and uncertain tax position tracker. The tracker is being amortized over three years, beginning in January 2013. The unamortized portion of investment tax credit is being amortized over the expected life of the underlying assets.
(w)
Estimated funds collected for the eventual dismantling and removal of plant from service, net of salvage value, upon retirement related to our rate-regulated operations.
(x)
A regulatory tracking mechanism for the difference between the level of bad debt expense incurred by Ameren Illinois under GAAP and the level of such costs included in electric and natural gas rates. The over-recovery relating to 2011 was refunded to customers from June 2012 through May 2013. The over-recovery relating to 2012 is being refunded to customers from June 2013 through May 2014. The over-recovery relating to 2013 will be refunded to customers from June 2013 through May 2014.
(y)
A regulatory tracking mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri under GAAP and the level of such costs built into rates. For periods prior to August 2012, the MoPSC's December 2012 electric rate order directed the amortization to occur over five years, beginning in January 2013. For periods after August 2012, the amortization period will be determined in a future Ameren Missouri electric rate case.
(z)
The Ameren Illinois balance relates its regulatory tracking mechanism to recover its electric and natural gas costs associated with developing, implementing, and evaluating customer energy efficiency and demand response programs. This over-recovery will be refunded to customers over the following 12 months after the plan year. The Ameren Missouri balance relates to its MEEIA program costs incurred and projected lost revenues compared to the amount previously collected from customers. Beginning in January 2014, a MEEIA rider allows Ameren Missouri to collect from or refund to customers any annual difference in the actual amounts incurred and the projected amounts collected from customers for the MEEIA program costs and its projected lost revenues. Under the MEEIA rider, collections from or refunds to customers occur one year after the program costs and projected lost revenues are incurred.
(aa)
Ameren Illinois' 2013 revenue requirement reconciliation adjustment calculated pursuant to the FERC's electric transmission formula ratemaking framework. This liability will be refunded to customers in 2015.
(ab)
Balance primarily includes the costs of renewable energy credits to fulfill Ameren Missouri's renewable energy portfolio requirement from August 2012 through December 2013, which were less than the amount included in rates. The amortization period for this over-recovery will be determined in a future Ameren Missouri electric rate case.
Ameren Missouri and Ameren Illinois continually assess the recoverability of their regulatory assets. Under current accounting standards, regulatory assets are charged to earnings when it is no longer probable that such amounts will be recovered through future revenues. To the extent that payments of regulatory liabilities are no longer probable, the amounts are credited to earnings.
Property And Plant, Net
PROPERTY AND PLANT, NET
PROPERTY AND PLANT, NET
The following table presents property and plant, net, for each of the Ameren Companies at December 31, 2013, and 2012:
 
 
Ameren
Missouri(a)
 
Ameren
Illinois
 
Other
 
Ameren(a)(b)
2013
 
 
 
 
 
 
 
 
Property and plant, at original cost:
 
 
 
 
 
 
 
 
Electric
 
$
15,964

 
$
5,426

 
$
336

 
$
21,726

Natural gas
 
413

 
1,562

 
—

 
1,975

 
 
16,377

 
6,988

 
336

 
23,701

Less: Accumulated depreciation and amortization
 
6,766

 
1,627

 
251

 
8,644

 
 
9,611

 
5,361

 
85

 
15,057

Construction work in progress:
 
 
 
 
 
 
 
 
Nuclear fuel in process
 
246

 
—

 
—

 
246

Other
 
595

 
228

 
79

 
902

Property and plant, net
 
$
10,452

 
$
5,589

 
$
164

 
$
16,205

2012
 
 
 
 
 
 
 
 
Property and plant, at original cost:
 
 
 
 
 
 
 
 
Electric
 
$
15,638

 
$
4,985

 
$
319

 
$
20,942

Natural gas
 
393

 
1,461

 
—

 
1,854

 
 
16,031

 
6,446

 
319

 
22,796

Less: Accumulated depreciation and amortization
 
6,614

 
1,495

 
237

 
8,346

 
 
9,417

 
4,951

 
82

 
14,450

Construction work in progress:
 
 
 
 
 
 
 
 
Nuclear fuel in process
 
317

 
—

 
—

 
317

Other
 
427

 
101

 
53

 
581

Property and plant, net
 
$
10,161

 
$
5,052

 
$
135

 
$
15,348



(a)
Amounts in Ameren and Ameren Missouri include two electric generation CTs under separate capital lease agreements. The gross cumulative asset value of those agreements was $228 million at December 31, 2013, and $228 million at December 31, 2012. The total accumulated depreciation associated with the two CTs was $56 million and $52 million at December 31, 2013, and 2012, respectively. In addition, Ameren Missouri has investments in debt securities, which were classified as held-to-maturity, related to the two CTs from the city of Bowling Green and Audrain County. As of December 31, 2013, and 2012, the carrying value of these debt securities was $299 million and $304 million, respectively.
(b)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
The following table provides accrued capital and nuclear fuel expenditures at December 31, 2013, 2012, and 2011, which represent noncash investing activity excluded from the accompanying statements of cash flows:
 
Ameren(a)
 
Ameren
Missouri
 
Ameren
Illinois
Accrued capital expenditures:
 
 
 
 
 
2013
$
175

 
$
74

 
$
86

2012
107

 
63

 
37

2011
97

 
73

 
18

Accrued nuclear fuel expenditures:
 
 
 
 
 
2013
8

 
8

 
(b)

2012
8

 
8

 
(b)

2011
36

 
36

 
(b)


(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
Not applicable.
Short-Term Debt And Liquidity
SHORT-TERM DEBT AND LIQUIDITY
SHORT-TERM DEBT AND LIQUIDITY
The liquidity needs of the Ameren Companies are typically supported through the use of available cash, short-term intercompany borrowings, drawings under committed bank credit agreements, or commercial paper issuances.
2012 Credit Agreements
On November 14, 2012, Ameren and Ameren Missouri entered into the $1 billion 2012 Missouri Credit Agreement. The 2010 Missouri Credit Agreement was terminated when the 2012 Missouri Credit Agreement when into effect. Also on November 14, 2012, Ameren and Ameren Illinois entered into the $1.1 billion 2012 Illinois Credit Agreement. The 2010 Illinois Credit Agreement was terminated when the 2012 Illinois Credit Agreement went into effect. These facilities cumulatively provide $2.1 billion of credit through November 14, 2017, which may be extended with the agreement of the lenders, subject to the terms of such agreements, for two additional one-year periods. The facilities currently include 24 international, national, and regional lenders, with no lender providing more than $125 million of credit in aggregate.
The obligations of each borrower under the respective 2012 Credit Agreements to which it is a party are several and not joint, and, except under limited circumstances relating to expenses and indemnities, the obligations of Ameren Missouri and Ameren Illinois under the respective 2012 Credit Agreements are not guaranteed by Ameren or any other subsidiary of Ameren. The maximum aggregate amount available to each borrower under each facility is shown in the following table (such amount being such borrower's "Borrowing Sublimit"):
 
 
2012 Missouri Credit Agreement
2012 Illinois
Credit Agreement
Ameren
$
500

$
300

Ameren Missouri
 
800

(a)

Ameren Illinois
 
(a)

800

(a)
Not applicable.
Ameren has the option to seek additional commitments from existing or new lenders to increase the total facility size of the 2012 Credit Agreements up to a maximum amount of $1.2 billion for the 2012 Missouri Credit Agreement and $1.3 billion for the 2012 Illinois Credit Agreement. The 2012 Credit Agreements, as well as the Borrowing Sublimits of Ameren and Ameren Missouri, will mature and expire on November 14, 2017. The Borrowing Sublimit of Ameren Illinois will mature and expire on September 30, 2014, subject to extension on a 364-day basis or for a longer period upon notice by the borrower of receipt of any and all required federal or state regulatory approvals, as permitted under the credit agreement, but in no event later than November 14, 2017. In October 2013, Ameren Illinois filed a petition seeking state regulatory approval necessary to extend the maturity date of its Borrowing Sublimit under the 2012 Illinois Credit Agreement to November 14, 2017. If and when regulatory approval is received, no lender approval will be required to effect the extension. The principal amount of each revolving loan owed by a borrower under any of the 2012 Credit Agreements to which it is a party will be due and payable no later than the final maturity date relating to such borrower under such 2012 Credit Agreements.
The obligations of all borrowers under the 2012 Credit Agreements are unsecured. Loans are available on a revolving basis under each of the 2012 Credit Agreements. Funds borrowed may be repaid and, subject to satisfaction of the conditions to borrowing, reborrowed from time to time. At the election of each borrower, the interest rates on such loans will be the alternate base rate ("ABR") plus the margin applicable to the particular borrower and/or the Eurodollar rate plus the margin applicable to the particular borrower. The applicable margins will be determined by the borrower's long-term unsecured credit ratings or, if no such ratings are then in effect, the borrower's corporate/issuer ratings then in effect. Letters of credit in an aggregate undrawn face amount not to exceed 25% of the applicable aggregate commitment under the respective 2012 Credit Agreements are also available for issuance for the account of the borrowers thereunder (but within the $2.1 billion overall combined facility borrowing limitations of the 2012 Credit Agreements).
The borrowers will use the proceeds from any borrowings under the 2012 Credit Agreements for general corporate purposes, including working capital, commercial paper liquidity support, loan funding under the Ameren money pool arrangements or other short-term intercompany loan arrangements, or paying fees and expenses incurred in connection with the 2012 Credit Agreements.
The 2012 Credit Agreements are used to borrow cash, to issue letters of credit, and to support issuances under Ameren's $500 million commercial paper program and Ameren Missouri's $500 million commercial paper program. Either of the 2012 Credit Agreements are available to Ameren to support issuances under Ameren's commercial paper program, subject to borrowing sublimits. The 2012 Missouri Credit Agreement is available to support issuances under Ameren Missouri's commercial paper program. Ameren Illinois' $500 million commercial paper program, under which no commercial paper was ever issued, was terminated in 2013. As of December 31, 2013, based on commercial paper outstanding and letters of credit issued under the 2012 Credit Agreements, the aggregate amount of credit capacity available to Ameren (parent), Ameren Missouri and Ameren Illinois, collectively, at December 31, 2013, was $1.7 billion.
Ameren, Ameren Missouri, and Ameren Illinois did not borrow under the 2012 Credit Agreements for the years ended December 31, 2013, and 2012.
Commercial Paper
The following table summarizes the borrowing activity and relevant interest rates under Ameren's commercial paper program, for the years ended December 31, 2013, and 2012:
 
 
2013
 
2012
Average daily borrowings outstanding
 
$
54

 
$
49

Outstanding borrowings at period-end
 
368

 
—

Weighted-average interest rate
 
0.56
%
 
0.92
%
Peak borrowings during period
 
$
368

 
$
229

Peak interest rate
 
0.85
%
 
1.25
%

Indebtedness Provisions and Other Covenants
The information below presents a summary of the Ameren Companies’ compliance with indebtedness provisions and other covenants.
The 2012 Credit Agreements contain conditions to borrowings and issuances of letters of credit, including the absence of default or unmatured default, material accuracy of representations and warranties (excluding any representation after the closing date as to the absence of material adverse change and material litigation, and the absence of any notice of violation, liability or requirement under any environmental laws that could have a material adverse effect), and obtaining required regulatory authorizations. In addition, as it relates to borrowings under the 2012 Illinois Credit Agreement, it is a condition for any such borrowing that, at the time of and after giving effect to such borrowing, the borrower not be in violation of any limitation on its ability to incur unsecured indebtedness contained in its articles of incorporation.
The 2012 Credit Agreements also contain nonfinancial covenants, including restrictions on the ability to incur liens, to transact with affiliates, to dispose of assets, to make investments in or transfer assets to its affiliates, and to merge with other entities. The 2012 Credit Agreements require each of Ameren, Ameren Missouri and Ameren Illinois to maintain consolidated indebtedness of not more than 65% of its consolidated total capitalization pursuant to a defined calculation set forth in the agreements. As of December 31, 2013, the ratios of consolidated indebtedness to total consolidated capitalization, calculated in accordance with the provisions of the 2012 Credit Agreements, were 48%, 47% and 44%, for Ameren, Ameren Missouri and Ameren Illinois, respectively. In addition, under the 2012 Illinois Credit Agreement and, by virtue of the cross-default provisions of the 2012 Missouri Credit Agreement, Ameren is required to maintain a ratio of consolidated funds from operations plus interest expense to consolidated interest expense of 2.0 to 1.0, to be calculated quarterly, as of the end of the most recent four fiscal quarters then ending, in accordance with the 2012 Illinois Credit Agreement. Ameren’s ratio as of December 31, 2013, was 5.3 to 1.0. Failure of a borrower to satisfy a financial covenant constitutes an immediate default under the applicable 2012 Credit Agreement.
The 2012 Credit Agreements contain default provisions that apply separately to each borrower, provided, however, that a default of Ameren Missouri or Ameren Illinois under the applicable 2012 Credit Agreement will also be deemed to constitute a default of Ameren under such agreement. Defaults include a cross-default to a default of such borrower under any other agreement covering outstanding indebtedness of such borrower and certain subsidiaries (other than project finance subsidiaries and nonmaterial subsidiaries) in excess of $50 million in the aggregate (including under the other 2012 Credit Agreement). However, under the default provisions of the 2012 Credit Agreements, any default of Ameren under any such 2012 Credit Agreements that results solely from a default of Ameren Missouri or Ameren Illinois thereunder does not result in a cross-default of Ameren under the other 2012 Credit Agreement. Further, the 2012 Credit Agreement default provisions provide that an Ameren default under any of the 2012 Credit Agreements does not trigger a default by Ameren Missouri or Ameren Illinois.
None of the Ameren Companies' credit agreements or financing arrangements contain credit rating triggers that would cause a default or acceleration of repayment of outstanding balances. Management believes that the Ameren Companies were in compliance with the provisions and covenants of their credit agreements at December 31, 2013.
Money Pools
Ameren has money pool agreements with and among its subsidiaries to coordinate and provide for certain short-term cash and working capital requirements. Ameren Services is responsible for the operation and administration of the money pool agreements.
Ameren Missouri, Ameren Illinois, and Ameren Services may participate in the utility money pool as both lenders and borrowers. Ameren may participate in the money pool only as a lender. Internal funds are surplus funds contributed to the money pool from participants. The primary sources of external funds for the money pool are the 2012 Credit Agreements and the commercial paper programs. The total amount available to the pool participants from the money pool at any given time is reduced by the amount of borrowings made by participants, but it is increased to the extent that the pool participants advance surplus funds to the money pool or remit funds from other external sources. The availability of funds is also determined by funding requirement limits established by regulatory authorizations. The money pool was established to coordinate and to provide short-term cash and working capital for the participants. Participants receiving a loan under the money pool agreement must repay the principal amount of such loan, together with accrued interest. The rate of interest depends on the composition of internal and external funds in the money pool. The average interest rate for borrowing under the money pool for the year ended December 31, 2013, was 0.14% (2012 - 0.13%).
See Note 14 – Related Party Transactions for the amount of interest income and expense from the money pool arrangements recorded by the Ameren Companies for the years ended December 31, 2013, 2012, and 2011.
Unilateral Borrowing Agreement
In addition, a unilateral borrowing agreement exists among Ameren, Ameren Illinois, and Ameren Services, which enables Ameren Illinois to make short-term borrowings directly from Ameren. The aggregate amount of borrowings outstanding at any time by Ameren Illinois under the unilateral borrowing agreement and the utility money pool agreement, together with any outstanding Ameren Illinois external credit facility borrowings, may not exceed $500 million, pursuant to authorization from the ICC. Ameren Illinois is not currently borrowing under the unilateral borrowing agreement.
Long-Term Debt And Equity Financings
LONG-TERM DEBT AND EQUITY FINANCINGS
LONG-TERM DEBT AND EQUITY FINANCINGS
The following table presents long-term debt outstanding, including maturities due within one year, for the Ameren Companies as of December 31, 2013, and 2012:
 
2013
 
2012
Ameren (Parent):
 
 
 
8.875% Senior unsecured notes due 2014
$
425

 
$
425

Less: Unamortized discount and premium
—

 
(1
)
Less: Maturities due within one year
(425
)
 
—

Long-term debt, net
$
—

 
$
424

Ameren Missouri:
 
 
 
Senior secured notes:(a)
 
 
 
4.65% Senior secured notes due 2013
—

 
200

5.50% Senior secured notes due 2014
104

 
104

4.75% Senior secured notes due 2015
114

 
114

5.40% Senior secured notes due 2016
260

 
260

6.40% Senior secured notes due 2017
425

 
425

6.00% Senior secured notes due 2018(b)
179

 
179

5.10% Senior secured notes due 2018
199

 
199

6.70% Senior secured notes due 2019(b)
329

 
329

5.10% Senior secured notes due 2019
244

 
244

5.00% Senior secured notes due 2020
85

 
85

5.50% Senior secured notes due 2034
184

 
184

5.30% Senior secured notes due 2037
300

 
300

8.45% Senior secured notes due 2039(b)
350

 
350

3.90% Senior secured notes due 2042(b)
485

 
485

Environmental improvement and pollution control revenue bonds:
 
 
 
1992 Series due 2022(c)(d)
47

 
47

1993 5.45% Series due 2028(e)
(e)

 
44

1998 Series A due 2033(c)(d)
60

 
60

1998 Series B due 2033(c)(d)
50

 
50

1998 Series C due 2033(c)(d)
50

 
50

Capital lease obligations:
 
 
 
City of Bowling Green capital lease (Peno Creek CT) through 2022
59

 
64

Audrain County capital lease (Audrain County CT) due 2023
240

 
240

Total long-term debt, gross
3,764

 
4,013

Less: Unamortized discount and premium
(7
)
 
(7
)
Less: Maturities due within one year
(109
)
 
(205
)
Long-term debt, net
$
3,648

 
$
3,801

 
2013
 
2012
Ameren Illinois:
 
 
 
Senior secured notes:
 
 
 
8.875% Senior secured notes due 2013(f)
$
—

 
$
150

6.20% Senior secured notes due 2016(f)
54

 
54

6.25% Senior secured notes due 2016(g)
75

 
75

6.125% Senior secured notes due 2017(g)(h)
250

 
250

6.25% Senior secured notes due 2018(g)(h)
144

 
144

9.75% Senior secured notes due 2018(g)(h)
313

 
313

2.70% Senior secured notes due 2022(g)(h)
400

 
400

6.125% Senior secured notes due 2028(g)
60

 
60

6.70% Senior secured notes due 2036(g)
61

 
61

6.70% Senior secured notes due 2036(f)
42

 
42

4.80% Senior secured notes due 2043(g)
280

 
—

Environmental improvement and pollution control revenue bonds:
 
 
 
5.90% Series 1993 due 2023(i)
32

 
32

5.70% 1994A Series due 2024(j)
36

 
36

1993 Series C-1 5.95% due 2026(k)
35

 
35

1993 Series C-2 5.70% due 2026(k)
8

 
8

1993 Series B-1 due 2028(d)(k)
17

 
17

5.40% 1998A Series due 2028(j)
19

 
19

5.40% 1998B Series due 2028(j)
33

 
33

Fair-market value adjustments
4

 
4

Total long-term debt, gross
1,863

 
1,733

Less: Unamortized discount and premium
(7
)
 
(6
)
Less: Maturities due within one year
—

 
(150
)
Long-term debt, net
$
1,856

 
$
1,577

Ameren consolidated long-term debt, net
$
5,504

 
$
5,802

(a)
These notes are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Missouri mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Missouri first mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the first mortgage bond lien protection associated with these notes to fall away until 2042.
(b)
Ameren Missouri has agreed, during the life of these notes, not to optionally redeem, purchase or otherwise retire in full its first mortgage bonds. Ameren Missouri has also agreed to prevent a first mortgage bond release date from occurring as long as any of the 8.45% senior secured notes due 2039 and any of the 3.90% senior secured notes due 2042 remain outstanding.
(c)
These bonds are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture and have a fall-away lien provision similar to that of Ameren Missouri's senior secured notes. The bonds are also backed by an insurance guarantee policy.
(d)
Interest rates, and periods during which such rates apply, vary depending on our selection of defined rate modes. Maximum interest rates could range up to 18% depending on the series of bonds. The average interest rates for 2013 and 2012 were as follows:
 
2013
 
2012
Ameren Missouri 1992 Series
0.17%
 
0.30%
Ameren Missouri 1998 Series A
0.34%
 
0.65%
Ameren Missouri 1998 Series B
0.33%
 
0.64%
Ameren Missouri 1998 Series C
0.34%
 
0.64%
Ameren Illinois 1993 Series B-1
0.14%
 
0.22%

(e)
These bonds are first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage bond indenture and are secured by substantially all Ameren Missouri property and franchises. The bonds are callable at 100% of par value. Less than $1 million principal amount of the bonds remain outstanding.
(f)
These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under the CILCO mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the CILCO mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the CILCO first mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the first mortgage bond lien protection associated with these notes to fall away until 2023.
(g)
These notes are collaterally secured by mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the Ameren Illinois mortgage indenture remain outstanding. Redemption, purchase, or maturity of all mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Illinois mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the mortgage bond lien protection associated with these notes to fall away until 2028.
(h)
Ameren Illinois has agreed, during the life of these notes, not to optionally redeem, purchase, or otherwise retire in full its Ameren Illinois mortgage bonds; therefore, an Ameren Illinois first mortgage bond release date will not occur as long as any of these notes are outstanding.
(i)
These bonds are first mortgage bonds issued by Ameren Illinois under the CILCO mortgage indenture and are secured by substantially all property of the former CILCO. The bonds are callable at 100% of par value.
(j)
These bonds are mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture and are secured by substantially all property of the former IP and CIPS. The bonds are callable at 100% of par value. The bonds are also backed by an insurance guarantee policy.
(k)
The bonds are callable at 100% of par value.
The following table presents the aggregate maturities of long-term debt, including current maturities, for the Ameren Companies at December 31, 2013:
 
 Ameren
(Parent)(a)
 
 Ameren
Missouri(a)
 
 Ameren
Illinois(a)(b)
 
Ameren
Consolidated
2014
$
425

 
$
109

 
$
—

 
$
534

2015
—

 
120

 
—

 
120

2016
—

 
266

 
129

 
395

2017
—

 
431

 
250

 
681

2018
—

 
383

 
457

 
840

Thereafter
—

 
2,455

 
1,023

 
3,478

Total
$
425

 
$
3,764

 
$
1,859

 
$
6,048

(a)
Excludes unamortized discount and premium of $7 million and $7 million at Ameren Missouri and Ameren Illinois, respectively.
(b)
Excludes $4 million related to Ameren Illinois’ long-term debt fair-market value adjustments, which are being amortized to interest expense over the remaining life of the debt.
All classes of Ameren Missouri’s and Ameren Illinois’ preferred stock are entitled to cumulative dividends and have voting rights. Preferred stock not subject to mandatory redemption of Ameren's subsidiaries was included in "Noncontrolling Interests" on Ameren's consolidated balance sheet. The following table presents the outstanding preferred stock of Ameren Missouri and Ameren Illinois that is not subject to mandatory redemption. The preferred stock is redeemable, at the option of the issuer, at the prices shown below as of December 31, 2013, and 2012:
 
 
 
Redemption Price(per share)
 
2013
 
2012
Ameren Missouri:
 
 
 
 
 
 
 
Without par value and stated value of $100 per share, 25 million shares authorized
 
 
 
 
 
 
$3.50 Series
130,000 shares
 
$
110.00

 
$
13

 
$
13

$3.70 Series
40,000 shares
 
104.75

 
4

 
4

$4.00 Series
150,000 shares
 
105.625

 
15

 
15

$4.30 Series
40,000 shares
 
105.00

 
4

 
4

$4.50 Series
213,595 shares
 
110.00

(a) 
21

 
21

$4.56 Series
200,000 shares
 
102.47

 
20

 
20

$4.75 Series
20,000 shares
 
102.176

 
2

 
2

$5.50 Series A
14,000 shares
 
110.00

 
1

 
1

Total
 
 
 
$
80

 
$
80

Ameren Illinois:
 
 
 
 
 
 
 
With par value of $100 per share, 2 million shares authorized
 
 
 
 
 
 
4.00% Series
144,275 shares
 
$
101.00

 
$
14

 
$
14

4.08% Series
45,224 shares
 
103.00

 
5

 
5

4.20% Series
23,655 shares
 
104.00

 
2

 
2

4.25% Series
50,000 shares
 
102.00

 
5

 
5

4.26% Series
16,621 shares
 
103.00

 
2

 
2

4.42% Series
16,190 shares
 
103.00

 
2

 
2

4.70% Series
18,429 shares
 
103.00

 
2

 
2

4.90% Series
73,825 shares
 
102.00

 
7

 
7

4.92% Series
49,289 shares
 
103.50

 
5

 
5

5.16% Series
50,000 shares
 
102.00

 
5

 
5

6.625% Series
124,274 shares
 
100.00

 
12

 
12

7.75% Series
4,542 shares
 
100.00

 
1

 
1

Total
 
 
 
$
62

 
$
62

Total Ameren
 
 
 
$
142

 
$
142

(a)
In the event of voluntary liquidation, $105.50.

Ameren has 100 million shares of $0.01 par value preferred stock authorized, with no shares outstanding. Ameren Missouri has 7.5 million shares of $1 par value preference stock authorized, with no such preference stock outstanding. Ameren Illinois has 2.6 million shares of no par value preferred stock authorized, with no shares outstanding.
Ameren
Ameren filed a Form S-8 registration statement with the SEC in October 2013, authorizing the offering of 4 million additional shares of its common stock under its 401(k) plan. Shares of common stock sold under the 401(k) plan are, at Ameren’s option, newly issued shares, treasury shares, or shares purchased in the open market or in privately negotiated transactions.
Ameren filed a Form S-3 registration statement with the SEC in June 2011, authorizing the offering of 6 million additional shares of its common stock under DRPlus. Shares of common stock sold under DRPlus are, at Ameren’s option, newly issued shares, treasury shares, or shares purchased in the open market or in privately negotiated transactions. In 2013 and 2012, Ameren shares were purchased in the open market for DRPlus and its 401(k) plan. Under DRPlus and its 401(k) plan, Ameren issued 2.2 million shares of common stock in 2011, which were valued at $65 million.
Ameren Missouri
In October 2013, $44 million of Ameren Missouri’s 1993 5.45% Series tax-exempt first mortgage bonds were redeemed at par value plus accrued interest, and $200 million of Ameren Missouri’s 4.65% senior secured notes matured and were retired.
On September 11, 2012, Ameren Missouri issued $485 million principal amount of 3.90% senior secured notes due September 15, 2042, with interest payable semiannually on March 15 and September 15 of each year, beginning March 15, 2013. These notes are secured by first mortgage bonds. Ameren Missouri received net proceeds of $478 million. The proceeds were used, together with other available cash, to provide the funds necessary to complete Ameren Missouri's tender offer on September 20, 2012, including the payment of interest and all related fees and expenses, and to retire the $173 million principal amount 5.25% senior secured notes that matured in September 2012.
On September 20, 2012, Ameren Missouri completed its tender offer to purchase for cash its outstanding 6.00% senior secured notes due 2018, 6.70% senior secured notes due 2019, 5.10% senior secured notes due 2018, and 5.10% senior secured notes due 2019. Any notes that were not tendered and purchased in the tender offer remain outstanding and continue to be obligations of Ameren Missouri. The following table sets forth the aggregate principal amount of each series of notes repurchased, along with certain other items related to the tender offer:
Senior Secured Notes
Principal Amount Repurchased
 
Premium Plus Accrued
and Unpaid Interest(a)
 
Principal Amount Outstanding After Tender Offer
6.00% senior secured notes due 2018
$
71

 
$
19

 
$
179

6.70% senior secured notes due 2019
121

 
35

 
329

5.10% senior secured notes due 2018
1

 
(b)

 
199

5.10% senior secured notes due 2019
56

 
12

 
244

(a)
The premiums paid in association with the tender offer were recorded as a regulatory asset and are being amortized over the life of the $485 million 3.90% senior secured notes due 2042.
(b)
Amount is less than $1 million.
Ameren Illinois
In January 2014, Ameren Illinois redeemed the following environmental improvement and pollution control revenue bonds at par value plus accrued interest:
Senior Secured Notes
Principal Amount
5.90% Series 1993 due 2023(a)
$
32

5.70% 1994A Series due 2024(a)
36

1993 Series C-1 5.95% due 2026
35

1993 Series C-2 5.70% due 2026
8

5.40% 1998A Series due 2028
19

5.40% 1998B Series due 2028
33

Total amount redeemed
$
163

(a)
Less than $1 million principal amount of the bonds remain outstanding as of January 31, 2014.
In December 2013, Ameren Illinois issued $280 million principal amount of 4.80% senior secured notes due December 15, 2043, with interest payable semiannually on June 15 and December 15 of each year, beginning June 15, 2014. These notes are secured by first mortgage bonds. Ameren Illinois received net proceeds of $276 million. The proceeds were used, together with other available cash, to repay at maturity $150 million aggregate principal amount of its 8.875% senior secured notes due December 15, 2013, and to repay its short-term debt.
On August 20, 2012, Ameren Illinois issued $400 million principal amount of 2.70% senior secured notes due September 1, 2022, with interest payable semiannually on March 1 and September 1 of each year, beginning March 1, 2013. These notes are secured by first mortgage bonds. Ameren Illinois received net proceeds of $397 million. The proceeds were used, together with other available cash, to provide the funds necessary to complete Ameren Illinois' tender offer on August 27, 2012, including the payment of interest and all related fees and expenses, and to redeem $51 million principal amount of 5.50% pollution control revenue bonds at par value plus accrued interest.
On August 27, 2012, Ameren Illinois completed its tender offer to purchase for cash its outstanding 9.75% senior secured notes due 2018 and 6.25% senior secured notes due 2018. Any notes that were not tendered and purchased in the tender offer remain outstanding and continue to be obligations of Ameren Illinois. The following table sets forth the aggregate principal amount of each series of notes repurchased, along with certain other items related to the tender offer:
Senior Secured Notes
Principal Amount Repurchased
 
Premium Plus Accrued
and Unpaid Interest(a)
 
Principal Amount Outstanding After Tender Offer
9.75% senior secured notes due 2018
$
87

 
$
36

 
$
313

6.25% senior secured notes due 2018
194

 
47

 
144

(a)
Premiums paid in the amount of $21 million in association with the tender offer were recorded as a regulatory asset and are being amortized over the life of the $400 million 2.70% senior secured notes due 2022. Premiums of $15 million were expensed in 2013 as a result of disallowances in the ICC's December 2013 electric and natural gas rate orders. See Note 2 – Rate and Regulatory Matters for further information regarding the disallowances.
In November 2012, $1 million principal amount of Ameren Illinois' 6.20% Series 1992B Pollution Control revenue bonds matured and were retired.
Indenture Provisions and Other Covenants
Ameren Missouri’s and Ameren Illinois’ indentures and articles of incorporation include covenants and provisions related to issuances of first mortgage bonds and preferred stock. Ameren Missouri and Ameren Illinois are required to meet certain ratios to issue additional first mortgage bonds and preferred stock. A failure to achieve these ratios would not result in a default under these covenants and provisions but would restrict the companies’ ability to issue bonds or preferred stock. The following table summarizes the required and actual interest coverage ratios for interest charges and dividend coverage ratios and bonds and preferred stock issuable as of December 31, 2013, at an assumed interest rate of 6% and dividend rate of 7%.
 
Required Interest
Coverage Ratio(a)
Actual Interest
Coverage Ratio
Bonds Issuable(b)
 
Required Dividend
Coverage Ratio(c)
Actual Dividend
Coverage Ratio
Preferred Stock
Issuable
Ameren Missouri
>2.0
4.5

$
3,831

  
>2.5
116.5

$
2,228

Ameren Illinois
>2.0
6.8

3,565

(d) 
>1.5
2.4

203

(a)
Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.
(b)
Amount of bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include bonds issuable based on retired bond capacity of $729 million and $365 million at Ameren Missouri and Ameren Illinois, respectively.
(c)
Coverage required on the annual dividend on preferred stock outstanding and to be issued, as required in the respective company’s articles of incorporation.
(d)
Amount of bonds issuable by Ameren Illinois based on unfunded property additions and retired bonds solely under the former IP mortgage indenture.
Ameren’s indenture does not require Ameren to comply with any quantitative financial covenants. The indenture does, however, include certain cross-default provisions. Specifically, either (1) the failure by Ameren to pay when due and upon expiration of any applicable grace period any portion of any Ameren indebtedness in excess of $25 million or (2) the acceleration upon default of the maturity of any Ameren indebtedness in excess of $25 million under any indebtedness agreement, including the 2012 Credit Agreements, constitutes a default under the indenture, unless such past due or accelerated debt is discharged or the acceleration is rescinded or annulled within a specified period.
Ameren Missouri and Ameren Illinois and certain other nonregistrant Ameren subsidiaries are subject to Section 305(a) of the Federal Power Act, which makes it unlawful for any officer or director of a public utility, as defined in the Federal Power Act, to participate in the making or paying of any dividend from any funds “properly included in capital account.” FERC has consistently interpreted the provision to allow dividends to be paid as long as (1) the source of the dividends is clearly disclosed, (2) the dividends are not excessive, and (3) there is no self-dealing on the part of corporate officials. At a minimum, Ameren believes that dividends can be paid by its subsidiaries that are public utilities from net income and retained earnings. In addition, under Illinois law, Ameren Illinois may not pay any dividend on its stock, unless, among other things, its earnings and earned surplus are sufficient to declare and pay a dividend after provision is made for reasonable and proper reserves, or unless Ameren Illinois has specific authorization from the ICC.
Ameren Illinois’ articles of incorporation require dividend payments on its common stock to be based on ratios of common stock to total capitalization and other provisions related to certain operating expenses and accumulations of earned surplus. Ameren Illinois committed to FERC to maintain a minimum 30% ratio of common stock equity to total capitalization. As of December 31, 2013, Ameren Illinois’ ratio of common stock equity to total capitalization was 55%.
In order for the Ameren Companies to issue securities in the future, they will have to comply with all applicable requirements in effect at the time of any such issuances.
Off-Balance-Sheet Arrangements
At December 31, 2013, none of the Ameren Companies had any off-balance-sheet financing arrangements, other than operating leases entered into in the ordinary course of business. None of the Ameren Companies expect to engage in any significant off-balance-sheet financing arrangements in the near future. See Note 16 – Divestiture Transactions and Discontinued Operations for Ameren (parent) guarantees and letters of credit issued to support New AER based on the transaction agreement with IPH.
Other Income And Expenses
OTHER INCOME AND EXPENSES
OTHER INCOME AND EXPENSES
The following table presents the components of "Other Income and Expenses" in the Ameren Companies’ statements of income (loss) for the years ended December 31, 2013, 2012, and 2011:
 
2013
 
2012
 
2011
 
Ameren:(a)
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
37

 
$
36

 
$
34

 
Interest income on industrial development revenue bonds
27

 
28

 
28

 
Interest and dividend income
3

 
4

(b) 
3

 
Other
2

 
2

 
3

 
Total miscellaneous income
$
69

 
$
70

 
$
68

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
12

 
$
24

(c) 
$
8

 
Other
14

 
13

 
15

 
Total miscellaneous expense
$
26

 
$
37

 
$
23

 
Ameren Missouri:
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
31

 
$
31

 
$
30

 
Interest income on industrial development revenue bonds
27

 
28

 
28

 
Interest and dividend income
—

 
4

(b) 
2

 
Other
—

 
—

 
1

 
Total miscellaneous income
$
58

 
$
63

 
$
61

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
4

 
$
9

 
$
3

 
Other
7

 
5

 
7

 
Total miscellaneous expense
$
11

 
$
14

 
$
10

 
Ameren Illinois:
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
6

 
$
5

 
$
4

 
Interest and dividend income
2

 
—

 
1

 
Other
2

 
2

 
2

 
Total miscellaneous income
$
10

 
$
7

 
$
7

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
4

 
$
11

(c) 
$
1

 
Other
5

 
6

 
5

 
Total miscellaneous expense
$
9

 
$
17

 
$
6

 
(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
Includes interest income received in 2012 relating to a refund of charges included in an expired power purchase agreement with Entergy. See Note 2 – Rate and Regulatory Matters for additional information.
(c)
Includes Ameren Illinois' one-time $7.5 million donation to the Illinois Science and Energy Innovation Trust pursuant to the IEIMA as a result of Ameren Illinois' 2012 participation in the electric delivery formula ratemaking process.
Derivative Financial Instruments
DERIVATIVE FINANCIAL INSTRUMENTS
DERIVATIVE FINANCIAL INSTRUMENTS
We use derivatives principally to manage the risk of changes in market prices for natural gas, diesel, power, and uranium. Such price fluctuations may cause the following:
•
an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices;
•
market values of natural gas and uranium inventories that differ from the cost of those commodities in inventory; and
•
actual cash outlays for the purchase of these commodities that differ from anticipated cash outlays.
The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty.

The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of December 31, 2013, and 2012. As of December 31, 2013, these contracts ran through October 2016, October 2019, May 2032, and October 2016 for fuel oils, natural gas, power, and uranium, respectively.
  
Quantity (in millions, except as indicated)
 
2013
2012
Commodity
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Fuel oils (in gallons)(a)
66
(b)
66
70
(b)
70
Natural gas (in mmbtu)
28
108
136
19
128
147
Power (in megawatthours)
3
11
14
11
14
25
Uranium (pounds in thousands)
796
(b)
796
446
(b)
446
 
 
 
 
 
 
 
 
 
 
 
 

(a)
Fuel oils consist of heating oil, ultra-low-sulfur diesel, and crude oil.
(b)
Not applicable.

Authoritative accounting guidance regarding derivative instruments requires that all contracts considered to be derivative instruments be recorded on the balance sheet at their fair values, unless the NPNS exception applies. See Note 8 – Fair Value Measurements for discussion of our methods of assessing the fair value of derivative instruments. Many of our physical contracts, such as our purchased power contracts, qualify for the NPNS exception to derivative accounting rules. The revenue or expense on NPNS contracts is recognized at the contract price upon physical delivery.
If we determine that a contract meets the definition of a derivative and is not eligible for the NPNS exception, we review the contract to determine if it qualifies for hedge accounting. We also consider whether gains or losses resulting from such derivatives qualify for regulatory deferral. Derivative contracts that qualify for regulatory deferral are recorded at fair value, with changes in fair value recorded as regulatory assets or regulatory liabilities in the period in which the change occurs. Ameren Missouri and Ameren Illinois believe derivative gains and losses deferred as regulatory assets and regulatory liabilities are probable of recovery or refund through future rates charged to customers. Regulatory assets and regulatory liabilities are amortized to operating income as related losses and gains are reflected in rates charged to customers. Therefore, gains and losses on these derivatives have no effect on operating income. As of December 31, 2013, and 2012, all contracts that qualify for hedge accounting receive regulatory deferral.
Authoritative accounting guidance permits companies to offset fair value amounts recognized for the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a liability) against fair value amounts recognized for derivative instruments that are executed with the same counterparty under the same master netting arrangement. The Ameren Companies did not elect to adopt this guidance for any eligible commodity contracts.
The following table presents the carrying value and balance sheet location of all derivative instruments as of December 31, 2013, and 2012:
 
Balance Sheet Location
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2013
 
 
 
 
 
 
 
Derivative assets not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
Fuel oils
Other current assets
$
6

$
—

$
6

 
Other assets
 
3

 
—

 
3

Natural gas
Other current assets
 
1

 
1

 
2

Power
Other current assets
 
23

 
—

 
23

 
Total assets
$
33

$
1

$
34

Derivative liabilities not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
MTM derivative liabilities
$
(b)

$
—

$
2

 
Other current liabilities
 
2

 
—

 
—

 
Other deferred credits and liabilities
 
1

 
—

 
1

Natural gas
MTM derivative liabilities
 
(b)

 
27

 
32

 
Other current liabilities
 
5

 
—

 
—

 
Other deferred credits and liabilities
 
6

 
19

 
25

Power
MTM derivative liabilities
 
(b)

 
9

 
13

 
Other current liabilities
 
4

 
—

 
—

 
Other deferred credits and liabilities
 
—

 
99

 
99

Uranium
MTM derivative liabilities
 
(b)

 
—

 
5

 
Other current liabilities
 
5

 
—

 
—

 
Other deferred credits and liabilities
 
1

 
—

 
1

 
Total liabilities
$
24

$
154

$
178

2012
 
 
 
 
 
 
 
Derivative assets not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current assets
$
8

$
—

$
8

 
Other assets
 
4

 
—

 
4

Natural gas
Other current assets
 
—

 
1

 
1

 
Other assets
 
1

 
—

 
1

Power
Other current assets
 
14

 
—

 
14

 
Other assets
 
1

 
—

 
1

 
Total assets
$
28

$
1

$
29

Derivative liabilities not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
MTM derivative liabilities
$
(b)

$
—

$
2

 
Other current liabilities
 
2

 
—

 
—

 
Other deferred credits and liabilities
 
2

 
—

 
2

Natural gas
MTM derivative liabilities
 
(b)

 
56

 
64

 
Other current liabilities
 
8

 
—

 
—

 
Other deferred credits and liabilities
 
7

 
38

 
45

Power
MTM derivative liabilities
 
(b)

 
21

 
25

 
Other current liabilities
 
4

 
—

 
—

 
Other deferred credits and liabilities
 
—

 
90

 
90

Uranium
MTM derivative liabilities
 
(b)

 
—

 
1

 
Other current liabilities
 
1

 
—

 
—

 
Other deferred credits and liabilities
 
1

 
—

 
1

 
Total liabilities
$
25

$
205

$
230

(a)
Includes derivatives subject to regulatory deferral.
(b)
Balance sheet line item not applicable to registrant.

The following table presents the cumulative amount of pretax net gains (losses) on all derivative instruments deferred in regulatory assets or regulatory liabilities as of December 31, 2013, and 2012:
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2013
 
 
 
 
 
 
Cumulative gains (losses) deferred in regulatory liabilities or assets:
 
 
 
 
 
 
Fuel oils derivative contracts(a)
$
2

$
—

$
2

Natural gas derivative contracts(b)
 
(10
)
 
(45
)
 
(55
)
Power derivative contracts(c)
 
19

 
(108
)
 
(89
)
Uranium derivative contracts(d)
 
(6
)
 
—

 
(6
)
2012
 
 
 
 
 
 
Cumulative gains (losses) deferred in regulatory liabilities or assets:
 
 
 
 
 
 
Fuel oils derivative contracts(a)
$
4

$
—

$
4

Natural gas derivative contracts(b)
 
(14
)
 
(93
)
 
(107
)
Power derivative contracts(c)
 
12

 
(111
)
 
(99
)
Uranium derivative contracts(d)
 
(2
)
 
—

 
(2
)


(a)
Represents net gains on fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s transportation costs for coal through October 2016, as of December 31, 2013. Current gains deferred as regulatory liabilities include $3 million and $3 million at Ameren and Ameren Missouri as of December 31, 2013, respectively. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of December 31, 2013, respectively.
(b)
Represents net losses associated with natural gas derivative contracts. These contracts are a partial hedge of natural gas requirements through October 2019 at Ameren and Ameren Missouri and through March 2017 at Ameren Illinois, in each case as of December 31, 2013. Current gains deferred as regulatory liabilities include $2 million, $1 million, and $1 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2013. Current losses deferred as regulatory assets include $32 million, $5 million, and $27 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2013.
(c)
Represents net gains (losses) associated with power derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri, in each case as of December 31, 2013. Current gains deferred as regulatory liabilities include $23 million and $23 million at Ameren and Ameren Missouri, respectively, as of December 31, 2013. Current losses deferred as regulatory assets include $13 million, $4 million, and $9 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2013.
(d)
Represents net losses on uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri's uranium requirements through October 2016, as of December 31, 2013. Current losses deferred as regulatory assets include $5 million and $5 million at Ameren and Ameren Missouri as of December 31, 2013, respectively.
Derivative instruments are subject to various credit-related losses in the event of nonperformance by counterparties to the transaction. Exchange-traded contracts are supported by the financial and credit quality of the clearing members of the respective exchanges and have nominal credit risk. In all other transactions, we are exposed to credit risk. Our credit risk management program involves establishing credit limits and collateral requirements for counterparties, using master trading and netting agreements, and reporting daily exposure to senior management.
We believe that entering into master trading and netting agreements mitigates the level of financial loss that could result from default by allowing net settlement of derivative assets and liabilities. We generally enter into the following master trading and netting agreements: (1) the International Swaps and Derivatives Association Agreement, a standardized financial natural gas and electric contract; (2) the Master Power Purchase and Sale Agreement, created by the Edison Electric Institute and the National Energy Marketers Association, a standardized contract for the purchase and sale of wholesale power; and (3) the North American Energy Standards Board Inc. agreement, a standardized contract for the purchase and sale of natural gas. These master trading and netting agreements allow the counterparties to net settle sale and purchase transactions. Further, collateral requirements are calculated at the master trading and netting agreement level by counterparty.
Although Ameren had not previously elected to offset fair value amounts and collateral for derivative instruments executed with the same counterparty under the same master netting arrangement, authoritative accounting guidance, effective in the first quarter 2013, requires those amounts eligible to be offset to be presented both at the gross and net amounts. The following table provides the recognized gross derivative balances and the net amounts of those derivatives subject to an enforceable master netting arrangement or similar agreement as of December 31, 2013, and 2012:
 
 
 
 
Gross Amounts Not Offset in the Balance Sheet
 
 
 
 
Gross Amounts Recognized in the Balance Sheet
 
Derivative Instruments
 
Cash Collateral Received/Posted(a)
 
Net
Amount
2013
 
 
 
 
 
 
 
 
Commodity contracts eligible to be offset:
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
$
33

$
9

$
—

$
24

Ameren Illinois
 
1

 
1

 
—

 
—

Ameren
$
34

$
10

$
—

$
24

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
$
24

$
9

$
9

$
6

Ameren Illinois
 
154

 
1

 
15

 
138

Ameren
$
178

$
10

$
24

$
144

2012
 
 
 
 
 
 
 
 
Commodity contracts eligible to be offset:
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
$
28

$
9

$
—

$
19

Ameren Illinois
 
1

 
1

 
—

 
—

Ameren
$
29

$
10

$
—

$
19

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
$
25

$
9

$
7

$
9

Ameren Illinois
 
205

 
1

 
58

 
146

Ameren
$
230

$
10

$
65

$
155

(a)
Cash collateral received reduces gross asset balances and is included in “Other current liabilities” and “Other deferred credits and liabilities” on the balance sheet. Cash collateral posted reduces gross liability balances and is included in “Other current assets” and “Other assets” on the balance sheet.
Concentrations of Credit Risk
In determining our concentrations of credit risk related to derivative instruments, we review our individual counterparties and categorize each counterparty into groupings according to the primary business in which each engages. We calculate maximum exposures based on the gross fair value of financial instruments, including accrual and NPNS contracts. As of December 31, 2013, if counterparty groups were to fail completely to perform on contracts, Ameren, Ameren Missouri, and Ameren Illinois' maximum exposure was $13 million, $12 million, and $1 million, respectively. As of December 31, 2012, if counterparty groups were to fail completely to perform on contracts, Ameren, Ameren Missouri, and Ameren Illinois' maximum exposure was $23 million, $22 million, and $1 million, respectively. The potential loss on counterparty exposures is reduced by the application of master trading and netting agreements and collateral held to the extent of reducing the exposure to zero. As of December 31, 2013, the potential loss after consideration of the application of master trading and netting agreements and collateral held for Ameren and Ameren Missouri was $6 million and $6 million, respectively. As of December 31, 2012, the potential loss after consideration of the application of master trading and netting agreements and collateral held for Ameren and Ameren Missouri was $15 million and $15 million, respectively.
Derivative Instruments with Credit Risk-Related Contingent Features
Our commodity contracts contain collateral provisions tied to the Ameren Companies’ credit ratings. If we were to experience an adverse change in our credit ratings, or if a counterparty with reasonable grounds for uncertainty regarding performance of an obligation requested adequate assurance of performance, additional collateral postings might be required. The following table presents, as of December 31, 2013, and 2012, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a gross liability position, the cash collateral posted, and the aggregate amount of additional collateral that could be required to be posted with counterparties. The additional collateral required is the net liability position allowed under the master trading and netting agreements assuming (1) the credit risk-related contingent features underlying these agreements were triggered on December 31, 2013, or 2012, respectively, and (2) those counterparties with rights to do so requested collateral:
 
Aggregate Fair Value of
Derivative Liabilities(a)
 
Cash
Collateral Posted
 
Potential Aggregate Amount of
Additional Collateral Required(b)
2013
 
 
 
 
 
Ameren Missouri
$
70

 
$
2

 
$
67

Ameren Illinois
75

 
15

 
55

Ameren
$
145

 
$
17

 
$
122

2012
 
 
 
 
 
Ameren Missouri
$
78

 
$
3

 
$
71

Ameren Illinois
148

 
58

 
84

Ameren
$
226

 
$
61

 
$
155

(a)
Prior to consideration of master trading and netting agreements and including NPNS and accrual contract exposures.
(b)
As collateral requirements with certain counterparties are based on master trading and netting agreements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such agreements.

Derivatives Subject to Regulatory Deferral
The following table represents the net change in market value associated with derivatives that qualify for regulatory deferral for the years ended December 31, 2013 and 2012:
  
 
Gain (Loss) Recognized
in Regulatory Liabilities
or Regulatory Assets
2013
 
2012
Ameren (a)
Fuel oils
 
$
(2
)
 
$
(15
)
 
Natural gas
 
52

 
84

 
Power
 
10

 
(180
)
 
Uranium
 
(4
)
 
(1
)
 
Total
 
$
56

 
$
(112
)
Ameren Missouri
Fuel oils
 
$
(2
)
 
$
(15
)
 
Natural gas
 
4

 
10

 
Power
 
7

 
(9
)
 
Uranium
 
(4
)
 
(1
)
 
Total
 
$
5

 
$
(15
)
Ameren Illinois
Natural gas
 
$
48

 
$
74

 
Power
 
3

 
29

 
Total
 
$
51

 
$
103

(a)
Amounts include intercompany eliminations.
Fair Value Measurements
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS
Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We use various methods to determine fair value, including market, income, and cost approaches. With these approaches, we adopt certain assumptions that market participants would use in pricing the asset or liability, including assumptions about market risk or the risks inherent in the inputs to the valuation. Inputs to valuation can be readily observable, market-corroborated, or unobservable. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Authoritative accounting guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value. All financial assets and liabilities carried at fair value are classified and disclosed in one of the following three hierarchy levels:
Level 1: Inputs based on quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities are primarily exchange-traded derivatives and assets, including cash and cash equivalents and listed equity securities, such as those held in Ameren Missouri’s nuclear decommissioning trust fund.
The market approach is used to measure the fair value of equity securities held in Ameren Missouri's nuclear decommissioning trust fund. Equity securities in this fund are representative of the S&P 500 index, excluding securities of Ameren Corporation, owners and/or operators of nuclear power plants and the trustee and investment managers. The S&P 500 index comprises stocks of large capitalization companies.
Level 2: Market-based inputs corroborated by third-party brokers or exchanges based on transacted market data. Level 2 assets and liabilities include certain assets held in Ameren Missouri’s nuclear decommissioning trust fund, including corporate bonds and other fixed-income securities, United States treasury and agency securities, and certain over-the-counter derivative instruments, including natural gas and financial power transactions.
Fixed income securities are valued using prices from independent industry recognized data vendors who provide values that are either exchange-based or matrix-based. The fair value measurements of fixed income securities classified as Level 2 are based on inputs other than quoted prices that are observable for the asset or liability. Examples are matrix pricing, market corroborated pricing, and inputs such as yield curves and indices. Level 2 fixed income securities in the nuclear decommissioning trust fund are primarily corporate bonds, asset-backed securities and United States agency bonds.
Derivative instruments classified as Level 2 are valued by corroborated observable inputs, such as pricing services or prices from similar instruments that trade in liquid markets. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. To derive our forward view to price our derivative instruments at fair value, we average the midpoints of the bid/ask spreads. To validate forward prices obtained from outside parties, we compare the pricing to recently settled market transactions. Additionally, a review of all sources is performed to identify any anomalies or potential errors. Further, we consider the volume of transactions on certain trading platforms in our reasonableness assessment of the averaged midpoint. Natural gas derivative contracts are valued based upon exchange closing prices without significant unobservable adjustments. Power derivatives contracts are valued based upon the use of multiple forward prices provided by third parties. The prices are averaged and shaped to a monthly profile when needed without significant unobservable adjustments.
Level 3: Unobservable inputs that are not corroborated by market data. Level 3 assets and liabilities are valued by internally developed models and assumptions or methodologies that use significant unobservable inputs. Level 3 assets and liabilities include derivative instruments that trade in less liquid markets, where pricing is largely unobservable. We value Level 3 instruments by using pricing models with inputs that are often unobservable in the market, as well as certain internal assumptions. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. As a part of our reasonableness review, an evaluation of all sources is performed to identify any anomalies or potential errors.
We perform an analysis each quarter to determine the appropriate hierarchy level of the assets and liabilities subject to fair value measurements. Financial assets and liabilities are classified in their entirety according to the lowest level of input that is significant to the fair value measurement. All assets and liabilities whose fair value measurement is based on significant unobservable inputs are classified as Level 3.
The following table describes the valuation techniques and unobservable inputs for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the period ended December 31, 2013:
 
 
Fair Value
 
 
 
Weighted
 
 
Assets
Liabilities
Valuation Technique(s)
Unobservable Input
Range
Average
Level 3 Derivative asset and liability – commodity contracts(a):
 
 
 
Ameren
Fuel oils
$
8

$
(3
)
Option model
Volatilities(%)(b)
10 - 35
16
 
 
 
 
Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.26 - 2
1
 
Power(e)
21

(110
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)
25 - 51
32
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(1,594) - 945
305
 
 
 
 
 
Nodal basis($/MWh)(c)
(3) - (1)
(2)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.39 - 0.50
0.42
 
 
 
 
 
Ameren credit risk(%)(c)(d)
2
(f)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 5
5
 
 
 
 
 
Escalation rate(%)(b)(g)
3 - 4
4
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
 
Uranium
—

(6
)
Discounted cash flow
Average bid/ask consensus pricing($/pound)(b)
34 - 41
36
Ameren Missouri
Fuel oils
$
8

$
(3
)
Option model
Volatilities(%)(b)
10 - 35
16
 
 
 
 
Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.26 - 2
1
 
Power(e)
21

(2
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)
25 - 51
40
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(1,594) - 945
305
 
 
 
 
 
Nodal basis($/MWh)(c)
(3) - (1)
(2)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.39 - 0.50
0.42
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
2
(f)
 
Uranium
—

(6
)
Discounted cash flow
Average bid/ask consensus pricing($/pound)(b)
34 - 41
36
Ameren Illinois
Power(e)
$
—

$
(108
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(b)
27 - 36
30
 
 
 
 
 
Nodal basis($/MWh)(b)
(4) - 0
(2)
 
 
 
 
 
Ameren Illinois credit risk(%)(c)(d)
2
(f)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 5
5
 
 
 
 
 
Escalation rate(%)(b)(g)
3 - 4
4
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(c)
Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.
(d)
Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren, Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(e)
Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2017. Valuations beyond 2017 use fundamentally modeled pricing by month for peak and off-peak demand.
(f)
Not applicable.
(g)
Escalation rate applies to power prices 2026 and beyond.

The following table describes the valuation techniques and unobservable inputs for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2012:
 
 
Fair Value
 
 
 
Weighted
 
 
Assets
Liabilities
Valuation Technique
Unobservable Input
Range
Average
Level 3 Derivative asset and liability – commodity contracts(a):
 
 
 
Ameren
Fuel oils
$
8

$
(3
)
Option model
Volatilities(%)(b)
7 - 27
24
 
 
 
 
Discounted cash flow
Escalation rate(%)(b)
0.21 - 0.60
0.44
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.12 - 1
1
 
 
 
 
 
Ameren credit risk(%)(c)(d)
2
(e)
 
Power(f)
14

(114
)
Discounted cash flow
Average forward peak and off-peak power pricing - forwards/swaps($/MWh)(c)
22 - 47
31
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(281) - 1,851
178
 
 
 
 
 
Nodal basis($/MWh)(c)
(5) - (1)
(3)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.22 - 1
1
 
 
 
 
 
Ameren credit risk(%)(c)(d)
2 - 5
5
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 8
6
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
 
Uranium
—

(2
)
Discounted cash flow
Average forward uranium pricing($/pound)(b)
43 - 46
44
Ameren Missouri
Fuel oils
$
8

$
(3
)
Option model
Volatilities(%)(b)
7 - 27
24
 
 
 
 
Discounted cash flow
Escalation rate(%)(b)
0.21 - 0.60
0.44
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.12 - 1
1
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
2
(e)
 
Power(f)
14

(3
)
Discounted cash flow
Average forward peak and off-peak power pricing - forwards/swaps($/MWh)(c)
24 - 56
36
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(281) - 1,851
178
 
 
 
 
 
Nodal basis($/MWh)(c)
(5) - (1)
(2)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.22 - 1
1
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
2
(e)
 
Uranium
—

(2
)
Discounted cash flow
Average forward uranium pricing($/pound)(b)
43 - 46
44
Ameren Illinois
Power(f)
$
—

$
(111
)
Discounted cash flow
Average forward peak and off-peak power pricing - forwards/swaps($/MWh)(b)
22 - 47
30
 
 
 
 
 
Nodal basis($/MWh)(b)
(5) - (1)
(3)
 
 
 
 
 
Ameren Illinois credit risk(%)(c)(d)
5
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 8
6
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(c)
Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.
(d)
Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren, Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(e)
Not applicable.
(f)
Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2017. Valuations beyond 2017 use fundamentally modeled pricing by month for peak and off-peak demand.
In accordance with applicable authoritative accounting guidance, we consider nonperformance risk in our valuation of derivative instruments by analyzing the credit standing of our counterparties and considering any counterparty credit enhancements (e.g., collateral). The guidance also requires that the fair value measurement of liabilities reflect the nonperformance risk of the reporting entity, as applicable. Therefore, we have factored the impact of our credit standing, as well as any potential credit enhancements, into the fair value measurement of both derivative assets and derivative liabilities. Included in our valuation, and based on current market conditions, is a valuation adjustment for counterparty default derived from market data such as the price of credit default swaps, bond yields, and credit ratings. Ameren recorded no gains or losses related to valuation adjustments for counterparty default risk in 2013, 2012 or 2011. At December 31, 2013, the counterparty default risk liability valuation adjustment related to derivative contracts totaled $3 million, less than $1 million, and $3 million, for Ameren, Ameren Missouri, and Ameren Illinois, respectively. At December 31, 2012, the counterparty default risk liability valuation adjustment related to derivative contracts totaled $7 million, less than $1 million, and $7 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2013:
 
 
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Assets:
 
 
 
 
 
 
 
 
 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
1

 
$
—

 
$
8

 
$
9

 
Natural gas
 
—

 
2

 
—

 
2

 
Power
 
—

 
2

 
21

 
23

 
Total derivative assets – commodity contracts
 
$
1

 
$
4

 
$
29

 
$
34

 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
3

 
$
—

 
$
—

 
$
3

 
Equity securities:
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
332

 
—

 
—

 
332

 
Debt securities:
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
52

 
—

 
52

 
Municipal bonds
 
—

 
2

 
—

 
2

 
U.S. treasury and agency securities
 
—

 
94

 
—

 
94

 
Asset-backed securities
 
—

 
10

 
—

 
10

 
Other
 
—

 
1

 
—

 
1

 
Total nuclear decommissioning trust fund
 
$
335

 
$
159

 
$
—

 
$
494

 
Total Ameren
 
$
336

 
$
163

 
$
29

 
$
528

Ameren Missouri
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
1

 
$
—

 
$
8

 
$
9

 
Natural gas
 
—

 
1

 
—

 
1

 
Power
 
—

 
2

 
21

 
23

 
Total derivative assets – commodity contracts
 
$
1

 
$
3

 
$
29

 
$
33

 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
3

 
$
—

 
$
—

 
$
3

 
Equity securities:
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
332

 
—

 
—

 
332

 
Debt securities:
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
52

 
—

 
52

 
Municipal bonds
 
—

 
2

 
—

 
2

 
U.S. treasury and agency securities
 
—

 
94

 
—

 
94

 
Asset-backed securities
 
—

 
10

 
—

 
10

 
Other
 
—

 
1

 
—

 
1

 
Total nuclear decommissioning trust fund
 
$
335

 
$
159

 
$
—

 
$
494

 
Total Ameren Missouri
 
$
336

 
$
162

 
$
29

 
$
527

Ameren Illinois
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
1

 
$
—

 
$
1

Liabilities:
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
—

 
$
—

 
$
3

 
$
3

 
Natural gas
 
3

 
54

 
—

 
57

 
Power
 
—

 
2

 
110

 
112

 
Uranium
 
—

 
—

 
6

 
6

 
Total Ameren
 
$
3

 
$
56

 
$
119

 
$
178

Ameren Missouri
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
—

 
$
—

 
$
3

 
$
3

 
Natural gas
 
3

 
8

 
—

 
11

 
Power
 
—

 
2

 
2

 
4

 
Uranium
 
—

 
—

 
6

 
6

 
Total Ameren Missouri
 
$
3

 
$
10

 
$
11

 
$
24

Ameren Illinois
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
46

 
$
—

 
$
46

 
Power
 
—

 
—

 
108

 
108

 
Total Ameren Illinois
 
$
—

 
$
46

 
$
108

 
$
154

(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2012:
 
 
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant
Other
Unobservable
Inputs
(Level 3)
 
Total
 
Assets:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
4

 
$
—

 
$
8

 
$
12

 
 
Natural gas
 
—

 
2

 
—

 
2

 
 
Power
 
—

 
1

 
14

 
15

 
 
Total derivative assets – commodity contracts
 
$
4

 
$
3

 
$
22

 
$
29

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
264

 
—

 
—

 
264

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
47

 
—

 
47

 
 
Municipal bonds
 
—

 
1

 
—

 
1

 
 
U.S. treasury and agency securities
 
—

 
81

 
—

 
81

 
 
Asset-backed securities
 
—

 
11

 
—

 
11

 
 
Other
 
—

 
1

 
—

 
1

 
 
Total nuclear decommissioning trust fund
 
$
265

 
$
141

 
$
—

 
$
406

(b) 
 
Total Ameren
 
$
269

 
$
144

 
$
22

 
$
435

 
Ameren Missouri
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
4

 
$
—

 
$
8

 
$
12

 
 
Natural gas
 
—

 
1

 
—

 
1

 
 
Power
 
—

 
1

 
14

 
15

 
 
Total derivative assets – commodity contracts
 
$
4

 
$
2

 
$
22

 
$
28

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
264

 
—

 
—

 
264

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
47

 
—

 
47

 
 
Municipal bonds
 
—

 
1

 
—

 
1

 
 
U.S. treasury and agency securities
 
—

 
81

 
—

 
81

 
 
Asset-backed securities
 
—

 
11

 
—

 
11

 
 
Other
 
—

 
1

 
—

 
1

 
 
Total nuclear decommissioning trust fund
 
$
265

 
$
141

 
$
—

 
$
406

(b) 
 
Total Ameren Missouri
 
$
269

 
$
143

 
$
22

 
$
434

 
Ameren Illinois
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
1

 
$
—

 
$
1

 
Liabilities:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
1

 
$
—

 
$
3

 
$
4

 
 
Natural gas
 
7

 
102

 
—

 
109

 
 
Power
 
—

 
1

 
114

 
115

 
 
Uranium
 
—

 
—

 
2

 
2

 
 
Total Ameren
 
$
8

 
$
103

 
$
119

 
$
230

 
Ameren Missouri
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
1

 
$
—

 
$
3

 
$
4

 
 
Natural gas
 
7

 
8

 
—

 
15

 
 
Power
 
—

 
1

 
3

 
4

 
 
Uranium
 
—

 
—

 
2

 
2

 
 
Total Ameren Missouri
 
$
8

 
$
9

 
$
8

 
$
25

 
Ameren Illinois
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
94

 
$
—

 
$
94

 
 
Power
 
—

 
—

 
111

 
111

 
 
Total Ameren Illinois
 
$
—

 
$
94

 
$
111

 
$
205

 
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Balance excludes $2 million of receivables, payables, and accrued income, net.
The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2013:
  
 
Net Derivative Commodity Contracts
  
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
5

$
(a)

$
5

Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
—

 
(a)

 
—

Total realized and unrealized gains (losses)
 
—

 
(a)

 
—

Purchases
 
3

 
(a)

 
3

Sales
 
(1
)
 
(a)

 
(1
)
Settlements
 
(2
)
 
(a)

 
(2
)
Ending balance at December 31, 2013
$
5

$
(a)

$
5

Change in unrealized gains (losses) related to assets/liabilities held at December 31,2013
$
—

$
(a)

$
—

Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
—

$
—

$
—

Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
—

 
(1
)
 
(1
)
Total realized and unrealized gains (losses)
 
—

 
(1
)
 
(1
)
Purchases
 
—

 
1

 
1

Ending balance at December 31, 2013
$
—

$
—

$
—

Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013
$
—

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
11

$
(111
)
$
(100
)
Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
3

 
(18
)
 
(15
)
Total realized and unrealized gains (losses)
 
3

 
(18
)
 
(15
)
Purchases
 
40

 
—

 
40

Settlements
 
(36
)
 
21

 
(15
)
Transfers into Level 3
 
(3
)
 
—

 
(3
)
Transfers out of Level 3
 
4

 
—

 
4

Ending balance at December 31, 2013
$
19

$
(108
)
$
(89
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013
$
(1
)
$
(24
)
 $
(25
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
(2
)
$
(a)

$
(2
)
Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
(3
)
 
(a)

 
(3
)
Total realized and unrealized gains (losses)
 
(3
)
 
(a)

 
(3
)
Purchases
 
(2
)
 
(a)

 
(2
)
Settlements
 
1

 
(a)

 
1

Ending balance at December 31, 2013
$
(6
)
$
(a)

$
(6
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013
$
(2
)
$
(a)

$
(2
)

(a)
Not applicable.
The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2012:
  
 
Net Derivative Commodity Contracts
  
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2012
$
3

$
(a)

$
3

Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
(1
)
 
(a)

 
(1
)
Total realized and unrealized gains (losses)
 
(1
)
 
(a)

 
(1
)
Purchases
 
7

 
(a)

 
7

Sales
 
(3
)
 
(a)

 
(3
)
Settlements
 
(2
)
 
(a)

 
(2
)
Transfers into Level 3
 
1

 
(a)

 
1

Ending balance at December 31, 2012
$
5

$
(a)

$
5

Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2012
$
(1
)
$
(a)

$
(1
)
Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2012
$
(14
)
$
(160
)
$
(174
)
Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
(2
)
 
(25
)
 
(27
)
Total realized and unrealized gains (losses)
 
(2
)
 
(25
)
 
(27
)
Settlements
 
1

 
15

 
16

Transfers out of Level 3
 
15

 
170

 
185

Ending balance at December 31, 2012
$
—

$
—

$
—

Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2012
$
—

$
—

$
—

Power(b):
 
 
 
 
 
 
Beginning balance at January 1, 2012
$
21

$
(140
)
$
81

Realized and unrealized gains (losses):
 
 
 
 
 

Included in regulatory assets/liabilities
 
11

 
(226
)
 
(175
)
Total realized and unrealized gains (losses)
 
11

 
(226
)
 
(175
)
Purchases
 
21

 
—

 
21

Sales
 
(1
)
 
—

 
(1
)
Settlements
 
(37
)
 
255

 
(22
)
Transfers out of Level 3
 
(4
)
 
—

 
(4
)
Ending balance at December 31, 2012
$
11

$
(111
)
$
(100
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2012
$
—

$
(191
)
(c) $
(175
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2012
$
(1
)
$
(a)

$
(1
)
Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
(2
)
 
(a)

 
(2
)
Total realized and unrealized gains (losses)
 
(2
)
 
(a)

 
(2
)
Settlements
 
1

 
(a)

 
1

Ending balance at December 31, 2012
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2012
$
(1
)
$
(a)

$
(1
)
(a)
Not applicable.
(b)
Ameren amounts include intercompany eliminations.
(c)
The change in unrealized losses was due to decreases in long-term power prices applied to 20-year Ameren Illinois swap contracts, which expire in May 2032.
Transfers in or out of Level 3 represent either (1) existing assets and liabilities that were previously categorized as a higher level but were recategorized to Level 3 because the inputs to the model became unobservable during the period, or (2) existing assets and liabilities that were previously classified as Level 3 but were recategorized to a higher level because the lowest significant input became observable during the period. Transfers out of Level 3 into Level 2 for natural gas derivatives were due to management previously using broker quotations to estimate the fair value of natural gas contracts and changing to estimates based upon exchange closing prices without significant unobservable adjustments in 2012. Estimates of fair value based on exchange closing prices are deemed to be a more accurate approximation of natural gas prices. Transfers between Level 2 and Level 3 for power derivatives and between Level 1 and Level 3 for fuel oils were primarily caused by changes in availability of financial trades observable on electronic exchanges between the periods shown below. Any reclassifications are reported as transfers out of Level 3 at the fair value measurement reported at the beginning of the period in which the changes occur. For the years ended December 31, 2013 and 2012, there were no transfers between Level 1 and Level 2 related to derivative commodity contracts. The following table summarizes all transfers between fair value hierarchy levels related to derivative commodity contracts for the years ended December 31, 2013 and 2012:
 
2013
 
2012
Ameren - derivative commodity contracts:



Transfers into Level 3 / Transfers out of Level 1 – Fuel oils
$
—

 
$
1

Transfers out of Level 3 / Transfers into Level 2 – Natural gas
—

 
185

Transfers into Level 3 / Transfers out of Level 2 – Power
(3
)
 
—

Transfers out of Level 3 / Transfers into Level 2 – Power
4

 
(4
)
Net fair value of Level 3 transfers
$
1

 
$
182

Ameren Missouri - derivative commodity contracts:
 
 
 
Transfers into Level 3 / Transfers out of Level 1 – Fuel oils
$
—

 
$
1

Transfers out of Level 3 / Transfers into Level 2 – Natural gas
—

 
15

Transfers into Level 3 / Transfers out of Level 2 – Power
(3
)
 
—

Transfers out of Level 3 / Transfers into Level 2 – Power
4

 
(4
)
Net fair value of Level 3 transfers
$
1

 
$
12

Ameren Illinois - derivative commodity contracts:
 
 
 
 Transfers out of Level 3 / Transfers into Level 2 – Natural gas
$
—

 
$
170


See Note 11 – Retirement Benefits for the fair value hierarchy tables detailing Ameren’s pension and postretirement plan assets as of December 31, 2013, as well as a table summarizing the changes in Level 3 plan assets during 2013.
The Ameren Companies’ carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments and are considered to be Level 1 in the fair value hierarchy. Ameren's and Ameren Missouri's carrying amounts of investments in debt securities related to the two CTs from the city of Bowling Green and Audrain County approximate fair value. These investments are classified as held-to-maturity. These investments are considered Level 2 in the fair value hierarchy as they are valued based on similar market transactions. The Ameren Companies' short-term borrowings also approximate fair value because of their short-term nature. Short-term borrowings are considered to be Level 2 in the fair value hierarchy as they are valued based on market rates for similar market transactions. The estimated fair value of long-term debt and preferred stock is based on the quoted market prices for same or similar issuances for companies with similar credit profiles or on the current rates offered to the Ameren Companies for similar financial instruments, which fair value measurement is considered Level 2 in the fair value hierarchy.
The following table presents the carrying amounts and estimated fair values of our long-term debt and preferred stock at December 31, 2013 and 2012:
  
2013
 
2012
  
Carrying Amount
 
Fair Value
 
Carrying Amount
 
Fair Value
Ameren:(a)
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
6,038

 
$
6,584

 
$
6,157

 
$
7,110

Preferred stock
142

 
118

 
142

 
123

Ameren Missouri:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
3,757

 
$
4,124

 
$
4,006

 
$
4,625

Preferred stock
80

 
71

 
80

 
74

Ameren Illinois:
 
 
 
 
 
 
 
Long-term debt (including current portion)
$
1,856

 
$
2,028

 
$
1,727

 
$
2,020

Preferred stock
62

 
47

 
62

 
49

(a)
Preferred stock is recorded in "Noncontrolling Interests" on the consolidated balance sheet.
Nuclear Decommissioning Trust Fund Investments
NUCLEAR DECOMMISSIONING TRUST FUND INVESTMENTS
NUCLEAR DECOMMISSIONING TRUST FUND INVESTMENTS
Ameren Missouri has investments in debt and equity securities that are held in a trust fund for the purpose of funding the decommissioning of its Callaway energy center. We have classified these investments as available for sale, and we have recorded all such investments at their fair market value at December 31, 2013, and 2012. See Note 10 – Callaway Energy Center for additional information.
Investments in the nuclear decommissioning trust fund have a target allocation of 60% to 70% in equity securities, with the balance invested in debt securities.
The following table presents proceeds from the sale and maturities of investments in Ameren Missouri’s nuclear decommissioning trust fund and the gross realized gains and losses resulting from those sales for the years ended December 31, 2013, 2012, and 2011:
 
2013
 
2012
 
2011
Proceeds from sales and maturities
$
196

 
$
384

 
$
199

Gross realized gains
7

 
6

 
5

Gross realized losses
5

 
2

 
4


Net realized and unrealized gains and losses are deferred and recorded as regulatory assets or regulatory liabilities on Ameren’s and Ameren Missouri’s balance sheets. This reporting is consistent with the method used to account for the decommissioning costs recovered in rates. Gains or losses associated with assets in the trust fund could result in lower or higher funding requirements for decommissioning costs, which are expected to be reflected in electric rates paid by Ameren Missouri’s customers. See Note 2 – Rate and Regulatory Matters.
The following table presents the costs and fair values of investments in debt and equity securities in Ameren Missouri’s nuclear decommissioning trust fund at December 31, 2013, and 2012:
Security Type
Cost
 
Gross Unrealized Gain
 
Gross Unrealized Loss
 
Fair Value
2013
 
 
 
 
 
 
 
Debt securities
$
157

 
$
4

$
2

 
$
159

Equity securities
137

 
199

 
4

 
332

Cash
3

 
—

 
—

 
3

Other(b)
(a)

 
—

 
—

 
(a)

Total
$
297

 
$
203

$
6

 
$
494

2012
 
 
 
 
 
 
 
Debt securities
$
133

 
$
8

$
(a)

 
$
141

Equity securities
145

 
130

 
11

 
264

Cash
1

 
—

 
—

 
1

Other(b)
2

 
—

 
—

 
2

Total
$
281

 
$
138

$
11

 
$
408

(a)
Amount less than $1 million.
(b)
Represents payables relating to pending security purchases, net of receivables related to pending security sales and interest receivables.
The following table presents the costs and fair values of investments in debt securities in Ameren Missouri’s nuclear decommissioning trust fund according to their contractual maturities at December 31, 2013:
 
Cost
 
Fair Value
Less than 5 years
$
93

 
$
94

5 years to 10 years
31

 
32

Due after 10 years
33

 
33

Total
$
157

 
$
159


We have unrealized losses relating to certain available-for-sale investments included in our decommissioning trust fund, recorded as regulatory assets as discussed above. Decommissioning will not occur until the operating license for our nuclear energy center expires. Ameren Missouri submitted a license extension application to the NRC to extend the Callaway energy center’s operating license to 2044. The following table presents the fair value and the gross unrealized losses of the available-for-sale securities held in Ameren Missouri's nuclear decommissioning trust fund. They are aggregated by investment category and the length of time that individual securities have been in a continuous unrealized loss position at December 31, 2013:
  
Less than 12 Months
 
 
12 Months or Greater
 
Total
  
Fair Value
 
Gross
Unrealized
Losses
 
 
Fair Value
 
Gross
Unrealized
Losses
 
Fair Value
 
Gross
Unrealized
Losses
Debt securities
$
72

 
$
2

 
$
(a)

$
(a)

 
$
72

 
$
2

Equity securities
6

 
(a)

 
 
7

 
4

 
13

 
4

Total
$
78

 
$
2

 
$
7

$
4

 
$
85

 
$
6

(a)
Amount less than $1 million.
Callaway Energy Center
CALLAWAY ENERGY CENTER
CALLAWAY ENERGY CENTER
Under the NWPA, the DOE is responsible for disposing of spent nuclear fuel from the Callaway energy center and other commercial nuclear energy centers. Under the NWPA, Ameren and other utilities that own and operate those energy centers are responsible for paying the disposal costs. The NWPA established the fee that these utilities pay the federal government for disposing of the spent nuclear fuel at one mill, or one-tenth of one cent, for each kilowatthour generated by those plants and sold. The NWPA also requires the DOE to review the nuclear waste fee against the cost of the nuclear waste disposal program and to propose to the United States Congress any fee adjustment necessary to offset the costs of the program. As required by the NWPA, Ameren Missouri and other utilities have entered into standard contracts with the federal government. The government, represented by the DOE, is responsible for implementing these provisions of the NWPA. Consistent with the NWPA and its standard contract, Ameren Missouri collects one mill from its electric customers for each kilowatthour of electricity that it generates and sells from its Callaway energy center.
Although both the NWPA and the standard contract stated that the federal government would begin to dispose of spent nuclear fuel by 1998, the federal government is not meeting its disposal obligation. Ameren Missouri has sufficient installed capacity at the Callaway energy center to store its spent nuclear fuel generated through 2020, and it has the capability for additional storage capacity for spent nuclear fuel generated through the end of the energy center’s current licensed life. The DOE's delay in carrying out its obligation to dispose of spent nuclear fuel from the Callaway energy center is not expected to adversely affect the continued operations of the energy center.
In January 2009, the federal government announced that a spent nuclear fuel repository at Yucca Mountain, Nevada was unworkable. The federal government took steps to terminate the Yucca Mountain program, while acknowledging its continuing obligation to dispose of utilities’ spent nuclear fuel. In January 2013, the DOE issued its plan for the management and disposal of spent nuclear fuel. The DOE's plan calls for a pilot interim storage facility to begin operation with an initial focus on accepting spent nuclear fuel from shutdown reactor sites by 2021. By 2025, a larger interim storage facility would be available, co-located with the pilot facility. The plan also proposes to site a permanent geological repository by 2026, to characterize the site and to design and to license the repository by 2042, and to begin operation by 2048.
In view of the federal government's efforts to terminate the Yucca Mountain program, the Nuclear Energy Institute, a number of individual utilities, and the National Association of Regulatory Utility Commissioners sued the DOE in the United States Court of Appeals for the District of Columbia Circuit, seeking the suspension of the one mill nuclear waste fee, alleging that the DOE failed to undertake an appropriate fee adequacy review reflecting the current unsettled state of the nuclear waste program. In a June 2012 decision, the court ruled that DOE's fee adequacy review was legally inadequate and remanded the matter to the DOE. Although the court ruled it has the power to direct the DOE to suspend the fee, the court decided that it was premature to do so. Instead, the court ordered the DOE to provide within six months a revised assessment of the amount that should be collected. In January 2013, the DOE issued the revised assessment required by the court. The DOE determined that “neither insufficient nor excess revenues are being collected,” and it proposed no adjustment to the one mill nuclear waste fee. In November 2013, the court rejected the DOE's revised assessment and ordered the DOE to submit a proposal to the United States Congress to reduce the fee to zero. The DOE filed for rehearing, however there is no deadline for the court to act. In January 2014, the DOE, pursuant to the court's November 2013 order, submitted to Congress a proposal to reduce the fee to zero.
As a result of the DOE's failure to begin to dispose of the utilities' spent nuclear fuel and fulfill its contractual obligations, Ameren Missouri and other nuclear energy center owners have also sued the DOE to recover costs incurred for ongoing storage of their spent fuel. Ameren Missouri filed a breach of contract lawsuit to recover costs that it incurred through 2009. It sought reimbursement for the cost of reracking the Callaway energy center’s spent fuel pool, as well as certain NRC fees, and Missouri ad valorem taxes that Ameren Missouri would not have incurred had the DOE performed its contractual obligations. In June 2011, the parties reached a settlement agreement that included a payment to Ameren Missouri of $11 million for spent fuel storage and related costs through 2010. In addition, the settlement agreement provides for annual recovery of additional spent fuel storage and related costs incurred from 2011 through 2013 with the ability to extend the recovery period as mutually agreed to by the parties. The parties have agreed in principle to extend the recovery period through 2016. As a result of the settlement agreement, Ameren Missouri recorded a pretax reduction of $2 million and $2 million to its “Operating Expenses – Depreciation and amortization” and “Operating Expenses – Other operations and maintenance” expense line items, respectively, on its statement of income for the year ended December 31, 2011. In 2012, Ameren Missouri received a 2011 cost reimbursement of $1 million and reduced its "Property and plant, net" assets on its balance sheet by that amount. In 2013, Ameren Missouri received a 2012 cost reimbursement of $6 million and reduced its "Property and plant, net" assets on its balance sheet by that amount. In March 2014, Ameren Missouri plans to submit approximately $15 million of 2013 costs to the DOE for reimbursement pursuant to the settlement agreement. Ameren Missouri reduced its "Property and plant, net" assets by this amount with an offset to "Miscellaneous accounts and notes receivable" on its balance sheet as of December 31, 2013. Included in these reimbursements are costs related to a dry spent fuel storage facility Ameren Missouri is constructing at its Callaway energy center. Ameren Missouri intends to begin transferring spent fuel assemblies to this facility in 2015. Until the facility is completed, Ameren Missouri will, in accordance with the settlement agreement, apply for reimbursement from the DOE for the cost to construct the dry spent fuel storage facility along with related allowable costs.
In December 2011, Ameren Missouri submitted a license extension application to the NRC to extend its Callaway energy center's operating license from 2024 to 2044. There is no deadline by which the NRC must act on this application. Among the rules that the NRC has historically relied upon in approving license extensions are rules dealing with the storage of spent nuclear fuel at the reactor site and with the NRC's confidence that permanent disposal of spent nuclear fuel will be available when needed. In a June 2012 decision, the United States Court of Appeals for the District of Columbia Circuit vacated these rules and remanded the case to the NRC, holding that the NRC's obligations under the National Environmental Policy Act required a more thorough environmental analysis in support of the NRC's waste confidence decision. In June 2012, a number of groups petitioned the NRC to suspend final licensing decisions in certain NRC licensing proceedings, including the Callaway license extension, until the NRC completed its proceedings on the vacated rules. In August 2012, the NRC stated that it would not issue licenses dependent on the vacated rules until it appropriately addressed the court's remand. In September 2012, the NRC directed its staff to issue, within two years, a generic environmental impact statement and a final rule to address the court's ruling. The NRC also stated that a site-specific analysis of these issues could be conducted in rare circumstances. If the Callaway energy center's license is extended, additional spent fuel storage will be required.
Electric utility rates charged to customers provide for the recovery of the Callaway energy center's decommissioning costs, which include decontamination, dismantling, and site restoration costs, over an assumed 40-year life of the nuclear center, ending with the expiration of the energy center's current operating license in 2024. It is assumed that the Callaway energy center site will be decommissioned through the immediate dismantlement method and removed from service. Ameren and Ameren Missouri have recorded an ARO for the Callaway energy center decommissioning costs at fair value, which represents the present value of estimated future cash outflows. Decommissioning costs are included in the costs of service used to establish electric rates for Ameren Missouri's customers. These costs amounted to $7 million in each of the years 2013, 2012, and 2011. Every three years, the MoPSC requires Ameren Missouri to file an updated cost study and funding analysis for decommissioning its Callaway energy center. Electric rates may be adjusted at such times to reflect changed estimates. The last cost study and funding analysis were filed with the MoPSC in September 2011. In October 2012, the MoPSC issued an order approving the stipulation and agreement between Ameren Missouri and the MoPSC staff that maintained the current rate of deposits to the trust fund and the rate of return assumptions used in the analysis. If Ameren Missouri's operating license extension application is approved by the NRC, a revised funding analysis will be prepared, and the rates charged to customers will be adjusted accordingly to reflect the operating license extension at the time the next triennial cost study and funding analysis is approved by the MoPSC. Amounts collected from customers are deposited in an external trust fund to provide for the Callaway energy center's decommissioning. If the assumed return on trust assets is not earned, we believe that it is probable that any such earnings deficiency will be recovered in rates. The fair value of the nuclear decommissioning trust fund for Ameren Missouri's Callaway energy center is reported as "Nuclear decommissioning trust fund" in Ameren's and Ameren Missouri's balance sheets. This amount is legally restricted and may be used only to fund the costs of nuclear decommissioning. Changes in the fair value of the trust fund are recorded as an increase or decrease to the nuclear decommissioning trust fund, with an offsetting adjustment to the related regulatory liability.
See Note 2 – Rate and Regulatory Matters and Note 9 – Nuclear Decommissioning Trust Fund Investments for additional information related to the Callaway energy center.
Retirement Benefits
RETIREMENT BENEFITS
RETIREMENT BENEFITS
The primary objective of the Ameren pension and postretirement benefit plans is to provide eligible employees with pension and postretirement health care and life insurance benefits. Ameren offers defined benefit pension and postretirement benefit plans covering substantially all of its employees. Ameren uses a measurement date of December 31 for its pension and postretirement benefit plans. Ameren Missouri and Ameren Illinois each participate in Ameren’s single-employer pension and other postretirement plans. Ameren’s qualified pension plan is the Ameren Retirement Plan. Ameren also has an unfunded nonqualified pension plan, the Ameren Supplemental Retirement Plan, which is available for certain management employees and retirees to provide a supplemental benefit when their qualified pension plan benefits are capped to comply with Internal Revenue Code limitations. Ameren’s other postretirement plans are the Ameren Retiree Medical Plan and the Ameren Group Life Insurance Plan. Nonaffiliated Ameren companies do not participate in the Ameren Retirement Plan, the Ameren Supplemental Retirement Plan, the Ameren Retiree Medical Plan, or the Ameren Group Life Insurance Plan.
On December 2, 2013, Ameren completed the divestiture of New AER to IPH. In accordance with the transaction agreement, Ameren retained the pension obligations as of December 2, 2013, associated with the current and former employees of New AER and its subsidiaries who were included in the Ameren Retirement Plan and the Ameren Supplemental Retirement Plan. Ameren also retained the postretirement benefit obligations associated with the employees of New AER and its subsidiaries who were eligible to retire at December 2, 2013, from the Ameren Retiree Medical Plan and the Ameren Group Life Insurance Plan. IPH assumed the existing pension and other postretirement benefit obligations associated with EEI's current and former employees that are included in EEI’s single-employer pension and other postretirement plans. Coincident with Ameren’s divestiture of New AER, a significant number of employees left Ameren which required a measurement of Ameren’s pension and postretirement benefit plan assets and obligations as of December 2, 2013, based upon current market conditions. The reduction in obligations for the postretirement benefit plans and the accelerated recognition of gains previously recorded in accumulated other comprehensive income that had not previously been recognized through net periodic benefit cost for the pension and postretirement benefit plans resulted in a $19 million pretax curtailment gain, which was included in discontinued operations.
Ameren completed another measurement as of December 31, 2013, as is its historical accounting practice, based upon the market conditions at the end of the year. Excluding the EEI plans, which were assumed by IPH during 2013, Ameren’s unfunded obligation under its pension and other postretirement benefit plans was $461 million and $1,143 million as of December 31, 2013, and December 31, 2012, respectively. These net liabilities are recorded in "Other current liabilities," "Pension and other postretirement benefits," and "Other assets" on Ameren's consolidated balance sheet. The primary factors contributing to this unfunded obligation reduction during 2013 were a 75 basis point increase in the pension and other postretirement benefit plan discount rates used to determine the present value of the obligations, and asset returns being better than expected. The offset to the unfunded obligation reduction was primarily a reduction to "Regulatory assets" on Ameren's consolidated balance sheet.
The following table presents the net benefit liability recorded on the balance sheets of each of the Ameren Companies as of December 31, 2013, and 2012:
 
2013

2012

Ameren(a)
$
461

$
1,143

Ameren Missouri
191

464

Ameren Illinois
198

408

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Ameren recognizes the under-funded status of its pension and postretirement plans as a liability on its consolidated balance sheet, with offsetting entries to accumulated OCI and regulatory assets, in accordance with authoritative accounting guidance. The following table presents the funded status of our pension and postretirement benefit plans as of December 31, 2013, and 2012. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 2013, and 2012, that have not been recognized in net periodic benefit costs.
  
2013
 
2012
  
Pension Benefits(a)
 
Postretirement
Benefits(a)
 
Pension Benefits(a)
 
Postretirement
Benefits(a)
Accumulated benefit obligation at end of year
$
3,698

$
(b)

 
$
3,829

$
(b)

Change in benefit obligation:
 
 
 
 
 
 
 
Net benefit obligation at beginning of year
$
4,051

$
1,157

 
$
3,764

$
1,145

Service cost
91

 
22

 
81

 
22

Interest cost
163

 
46

 
166

 
47

Participant contributions
—

 
16

 
—

 
16

Actuarial (gain) loss
(207
)
 
(76
)
 
240

 
(10
)
Curtailment gain(c)
—

 
(3
)
 
—

 
—

Settlement(d)
—

 
(5
)
 
—

 
—

Benefits paid
(198
)
 
(64
)
 
(200
)
 
(69
)
Early retiree reinsurance program receipt
(b)

 
—

 
(b)

 
2

Federal subsidy on benefits paid
(b)

 
3

 
(b)

 
4

Net benefit obligation at end of year
3,900

 
1,096

 
4,051

 
1,157

Change in plan assets:
 
 
 
 
 
 
 
Fair value of plan assets at beginning of year
3,127

 
938

 
2,814

 
836

Actual return on plan assets
376

 
156

 
385

 
104

Employer contributions
156

 
25

 
128

 
45

Federal subsidy on benefits paid
(b)

 
3

 
(b)

 
4

Early retiree reinsurance program receipt
(b)

 
—

 
(b)

 
2

Participant contributions
—

 
16

 
—

 
16

Benefits paid
(198
)
 
(64
)
 
(200
)
 
(69
)
Fair value of plan assets at end of year
3,461

 
1,074

 
3,127

 
938

Funded status – deficiency
439

 
22

 
924

 
219

Accrued benefit cost at December 31
$
439

$
22

 
$
924

$
219

Amounts recognized in the balance sheet consist of:
 
 
 
 
 
 
 
Noncurrent asset(e)
$
—

$
(9
)
 
$
—

$
—

Current liability(f)
3

 
1

 
3

 
2

Noncurrent liability
436

 
30

 
921

 
217

Net liability recognized
$
439

$
22

 
$
924

$
219

Amounts recognized in regulatory assets consist of:
 
 
 
 
 
 
 
Net actuarial (gain) loss
$
282

$
(71
)
 
$
699

$
103

Prior service cost (credit)
(7
)
 
(20
)
 
(6
)
 
(24
)
Amounts (pretax) recognized in accumulated OCI consist of:
 
 
 
 
 
 
 
Net actuarial (gain) loss
17

 
(12
)
 
65

 
5

Prior service cost (credit)
—

 
(1
)
 
(14
)
 
(6
)
Total
$
292

$
(104
)
 
$
744

$
78

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
Not applicable.
(c)
Effective with the divestiture of New AER on December 2, 2013, the liability for active management employees of New AER and its subsidiaries not eligible to retire were neither transferred to IPH nor retained by Ameren, which resulted in a curtailment gain. See Note 16 – Divestiture Transactions and Discontinued Operations for further information on the divestiture.
(d)
Effective with the divestiture of New AER on December 2, 2013, the liability for active union employees of New AER and its subsidiaries not eligible to retire was transferred to IPH based on the assumption of the collective bargaining agreements in place, which resulted in a settlement. See Note 16 – Divestiture Transactions and Discontinued Operations for further information on the divestiture.
(e)
Included in "Other assets" on Ameren's consolidated balance sheet.
(f)
Included in "Other current liabilities" on Ameren's consolidated balance sheet.

The following table presents the assumptions used to determine our benefit obligations at December 31, 2013, and 2012:
  
Pension Benefits
 
Postretirement Benefits
  
2013
 
2012
 
2013
 
2012
Discount rate at measurement date
4.75
%
 
4.00
%
 
4.75
%
 
4.00
%
Increase in future compensation
3.50

 
3.50

 
3.50

 
3.50

Medical cost trend rate (initial)
—

 
—

 
5.00

 
5.00

Medical cost trend rate (ultimate)
—

 
—

 
5.00

 
5.00

Years to ultimate rate
—

 
—

 
—

 
—


Ameren determines discount rate assumptions by identifying a theoretical settlement portfolio of high-quality corporate bonds sufficient to provide for a plan's projected benefit payments, pursuant to authoritative accounting guidance on the determination of discount rates used for defined benefit plan obligations. The settlement portfolio of bonds is selected from a pool of over 500 high-quality corporate bonds.  A single discount rate is then determined; that rate results in a discounted value of the plan's benefit payments that equates to the market value of the selected bonds.
Funding
Pension benefits are based on the employees’ years of service and compensation. Ameren’s pension plan is funded in compliance with income tax regulations and federal funding or regulatory requirements. As a result, Ameren expects to fund its pension plan at a level equal to the greater of the pension expense or the legally required minimum contribution. Considering its assumptions at December 31, 2013, its investment performance in 2013, and its pension funding policy, Ameren expects to make annual contributions of $20 million to $100 million in each of the next five years, with aggregate estimated contributions of $270 million. We expect Ameren Missouri’s and Ameren Illinois’ portion of the future funding requirements to be 52%, and 47%, respectively. These amounts are estimates. They may change based on actual investment performance, changes in interest rates, changes in our assumptions, changes in government regulations, and any voluntary contributions. Our funding policy for postretirement benefits is primarily to fund the Voluntary Employee Beneficiary Association (VEBA) trusts to match the annual postretirement expense.
The following table presents the cash contributions made to our defined benefit retirement plan and to our postretirement plans during 2013, 2012, and 2011:
  
Pension Benefits
 
Postretirement Benefits
  
2013
 
2012
 
2011
 
2013
 
2012
 
2011
Ameren Missouri
$
60

 
$
52

 
$
43

 
$
10

 
$
9

 
$
9

Ameren Illinois
50

 
46

 
28

 
11

 
35

 
118

Other
46

 
30

 
25

 
4

 
1

 
2

Ameren(a)
156

 
128

 
96

 
25

 
45

 
129

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Investment Strategy and Policies
Ameren manages plan assets in accordance with the “prudent investor” guidelines contained in ERISA. The investment committee, to the extent authority is delegated to it by the finance committee of Ameren’s board of directors, implements investment strategy and asset allocation guidelines for the plan assets. The investment committee includes members of senior management. The investment committee’s goals are twofold: first, to ensure that sufficient funds are available to provide the benefits at the time they are payable; second, to maximize total return on plan assets and minimize expense volatility consistent with its tolerance for risk. Ameren delegates investment management to specialists in each asset class. As appropriate, Ameren provides the investment manager with guidelines that specify allowable and prohibited investment types. The investment committee regularly monitors manager performance and compliance with investment guidelines.
The expected return on plan assets assumption is based on historical and projected rates of return for current and planned asset classes in the investment portfolio. Projected rates of return for each asset class were estimated after an analysis of historical experience, future expectations, and the volatility of the various asset classes. After considering the target asset allocation for each asset class, we adjusted the overall expected rate of return for the portfolio for historical and expected experience of active portfolio management results compared with benchmark returns and for the effect of expenses paid from plan assets. Ameren will use an expected return on plan assets for its pension plan assets and postretirement plan assets of 7.25% and 7.00%, respectively, in 2014. No plan assets are expected to be returned to Ameren during 2014.
Ameren’s investment committee strives to assemble a portfolio of diversified assets that does not create a significant concentration of risks. The investment committee develops asset allocation guidelines between asset classes, and it creates diversification through investments in assets that differ by type (equity, debt, real estate, private equity), duration, market capitalization, country, style (growth or value) and industry, among other factors. The diversification of assets is displayed in the target allocation table below. The investment committee also routinely rebalances the plan assets to adhere to the diversification goals. The investment committee’s strategy reduces the concentration of investment risk; however, Ameren is still subject to overall market risk. The following table presents our target allocations for 2014 and our pension and postretirement plans’ asset categories as of December 31, 2013, and 2012.
Asset
Category
Target Allocation
2014
 
Percentage of Plan Assets at December  31,
2013
 
2012
Pension Plan:
 
 
 
 
 
Cash and cash equivalents
0 - 5  %
 
2
%
 
2
%
Equity securities:
 
 
 
 
 
U.S. large capitalization
29 - 39
 
36

 
34
%
U.S. small and mid-capitalization
2 - 12
 
8

 
7
%
International and emerging markets
9 - 19
 
14

 
13
%
Total equity
50 - 60
 
58

 
54
%
Debt securities
35 - 45
 
36

 
39
%
Real estate
0 -   9  
 
4

 
4
%
Private equity
0 -   4  
 
(a)

 
1
%
Total
 
 
100
%
 
100
%
Postretirement Plans:
 
 
 
 
 
Cash and cash equivalents
0 - 10 %
 
4
%
 
4
%
Equity securities:
 
 
 
 
 
U.S. large capitalization
33 - 43
 
41
%
 
40
%
U.S. small and mid-capitalization
3 - 13
 
8
%
 
8
%
International
10 - 20
 
14
%
 
14
%
Total equity
55 - 65
 
63
%
 
62
%
Debt securities
30 - 40
 
33
%
 
34
%
Total
 
 
100
%
 
100
%

(a)
Less than 1% of plan assets.
In general, the United States large capitalization equity investments are passively managed or indexed, whereas the international, emerging markets, United States small capitalization, and United States mid-capitalization equity investments are actively managed by investment managers. Debt securities include a broad range of fixed income vehicles. Debt security investments in high-yield securities, emerging market securities, and non-United States dollar-denominated securities are owned by the plans, but in limited quantities to reduce risk. Most of the debt security investments are under active management by investment managers. Real estate investments include private real estate vehicles; however, Ameren does not, by policy, hold direct investments in real estate property. Ameren’s investment in private equity funds consists of 9 different limited partnerships, with invested capital ranging from $0.1 million to $5 million each, which invest primarily in a diversified number of small United States-based companies. No further commitments may be made to private equity investments without approval by the finance committee of the board of directors. Additionally, Ameren’s investment committee allows investment managers to use derivatives, such as index futures, exchange traded funds, foreign exchange futures, and options, in certain situations, to increase or to reduce market exposure in an efficient and timely manner.
Fair Value Measurements of Plan Assets
Investments in the pension and postretirement benefit plans were stated at fair value as of December 31, 2013. The fair value of an asset is the amount that would be received upon sale in an orderly transaction between market participants at the measurement date. Cash and cash equivalents have initial maturities of three months or less and are recorded at cost plus accrued interest. The carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments. Investments traded in active markets on national or international securities exchanges are valued at closing prices on the last business day on or before the measurement date. Securities traded in over-the-counter markets are valued based on quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Derivative contracts are valued at fair value, as determined by the investment managers (or independent third parties on behalf of the investment managers), who use proprietary models and take into consideration exchange quotations on underlying instruments, dealer quotations, and other market information. The fair value of real estate is based on annual appraisal reports prepared by an independent real estate appraiser.
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2013:
 
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Cash and cash equivalents
$
5

 
$
39

 
$
—

 
$
44

Equity securities:
 
 
 
 
 
 
 
U.S. large capitalization
107

 
1,162

 
—

 
1,269

U.S. small and mid-capitalization
273

 
—

 
—

 
273

International and emerging markets
143

 
372

 
—

 
515

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
860

 
—

 
860

Municipal bonds
—

 
149

 
—

 
149

U.S. treasury and agency securities
—

 
256

 
—

 
256

Other
—

 
27

 
—

 
27

Real estate
—

 
—

 
131

 
131

Private equity
—

 
—

 
15

 
15

Derivative assets
1

 
—

 
—

 
1

Derivative liabilities
(1
)
 
—

 
—

 
(1
)
Total
$
528

 
$
2,865

 
$
146

 
$
3,539

Less: Medical benefit assets at December 31(a)
 
 
 
 
 
 
(112
)
Plus: Net receivables at December 31(b)
 
 
 
 
 
 
34

Fair value of pension plans assets at year end
 
 
 
 
 
 
$
3,461

(a)
Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation.
(b)
Receivables related to pending security sales, offset by payables related to pending security purchases.
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2012:
 
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Cash and cash equivalents
$
1

 
$
28

 
$
—

 
$
29

Equity securities:
 
 
 
 
 
 
 
U.S. large capitalization
83

 
1,007

 
—

 
1,090

U.S. small and mid-capitalization
235

 
—

 
—

 
235

International and emerging markets
134

 
301

 
—

 
435

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
832

 
—

 
832

Municipal bonds
—

 
176

 
—

 
176

U.S. treasury and agency securities
—

 
250

 
—

 
250

Other
—

 
17

 
—

 
17

Real estate
—

 
—

 
118

 
118

Private equity
—

 
—

 
19

 
19

Derivative assets
—

 
—

 
—

 
—

Derivative liabilities
(1
)
 
—

 
—

 
(1
)
Total
$
452

 
$
2,611

 
$
137

 
$
3,200

Less: Medical benefit assets at December 31(a)
 
 
 
 
 
 
(102
)
Plus: Net receivables at December 31(b)
 
 
 
 
 
 
29

Fair value of pension plans assets at year end
 
 
 
 
 
 
$
3,127

(a)
Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation.
(b)
Receivables related to pending security sales, offset by payables related to pending security purchases.
The following table summarizes the changes in the fair value of the pension plan assets classified as Level 3 in the fair value hierarchy for each of the years ended December 31, 2013, and 2012:
 
Beginning
Balance at
January 1,
 
Actual Return on
Plan Assets Related
to Assets Still Held
at the Reporting Date
 
Actual Return on
Plan Assets Related
to Assets Sold
During the Period
 
Purchases,
Sales, and
Settlements, Net
 
Net
Transfers
into (out of)
of Level 3
 
Ending Balance at
December 31,
2013:
 
 
 
 
 
 
 
 
 
 
 
Real estate
$
118

 
$
9

 
$
—

 
$
4

 
$
—

 
$
131

Private equity
19

 
(9
)
 
11

 
(6
)
 
—

 
15

2012:
 
 
 
 
 
 
 
 
 
 
 
Real estate
$
108

 
$
7

 
$
—

 
$
3

 
$
—

 
$
118

Private equity
23

 
(7
)
 
8

 
(5
)
 
—

 
19


The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2013:
 
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Cash and cash equivalents
$
77

 
$
—

 
$
—

 
$
77

Equity securities:
 
 
 
 
 
 
 
U.S. large capitalization
297

 
101

 
—

 
398

U.S. small and mid-capitalization
77

 
—

 
—

 
77

International
39

 
96

 
—

 
135

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
89

 
—

 
89

Municipal bonds
—

 
103

 
—

 
103

U.S. treasury and agency securities
—

 
72

 
—

 
72

Asset-backed securities
—

 
10

 
—

 
10

Other
—

 
40

 
—

 
40

Total
$
490

 
$
511

 
$
—

 
$
1,001

Plus: Medical benefit assets at December 31(a)
 
 
 
 
 
 
112

Less: Net payables at December 31(b)
 
 
 
 
 
 
(39
)
Fair value of postretirement benefit plans assets at year end
 
 
 
 
 
 
$
1,074

(a)
Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.
(b)
Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2012:
 
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Cash and cash equivalents
$
83

 
$
—

 
$
—

 
$
83

Equity securities:
 
 
 
 
 
 
 
U.S. large capitalization
245

 
88

 
—

 
333

U.S. small and mid-capitalization
66

 
—

 
—

 
66

International
45

 
69

 
—

 
114

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
88

 
—

 
88

Municipal bonds
—

 
91

 
—

 
91

U.S. treasury and agency securities
—

 
67

 
—

 
67

Asset-backed securities
—

 
18

 
—

 
18

Other
—

 
22

 
—

 
22

Total
$
439

 
$
443

 
$
—

 
$
882

Plus: Medical benefit assets at December 31(a)
 
 
 
 
 
 
102

Less: Net payables at December 31(b)
 
 
 
 
 
 
(46
)
Fair value of postretirement benefit plans assets at year end
 
 
 
 
 
 
$
938

(a)
Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.
(b)
Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.
Net Periodic Benefit Cost
The following table presents the components of the net periodic benefit cost of our pension and postretirement benefit plans during 2013, 2012, and 2011:
 
Pension Benefits
Ameren(a)
 
Postretirement Benefits
Ameren(a)
2013
 
 
 
Service cost
$
91

 
$
22

Interest cost
163

 
46

Expected return on plan assets
(218
)
 
(62
)
Amortization of:
 
 
 
Transition obligation
—

 
—

Prior service cost
(2
)
 
(6
)
Actuarial loss
87

 
8

Curtailment gain
(12
)
 
(7
)
Net periodic benefit cost(b)
$
109

 
$
1

2012
 
 
 
Service cost
$
81

 
$
22

Interest cost
166

 
47

Expected return on plan assets
(208
)
 
(56
)
Amortization of:
 
 
 
Transition obligation
—

 
2

Prior service cost
(3
)
 
(6
)
Actuarial loss
75

 
5

Net periodic benefit cost(c)
$
111

 
$
14

2011
 
 
 
Service cost
$
73

 
$
20

Interest cost
175

 
54

Expected return on plan assets
(211
)
 
(50
)
Amortization of:
 
 
 
Transition obligation
—

 
2

Prior service cost
(1
)
 
(6
)
Actuarial loss
41

 
3

Net periodic benefit cost(c)
$
77

 
$
23

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
The net periodic benefit cost includes a $6 million and a $7 million net gain for pension benefits and postretirement benefits, respectively, which was included in "Income (loss) from discontinued operations, net of taxes" on Ameren's consolidated statement of income (loss). This net gain includes the curtailment gain recognized in 2013 as a result of a significant reduction in employees as of the December 2, 2013 closing date of the New AER divestiture. See Note 16 – Divestiture Transactions and Discontinued Operations for additional information on the divestiture.
(c)
The net periodic benefit cost includes $9 million and $- million in total net costs for pension benefits and postretirement benefits, respectively, for 2012 which were included in "Income (loss) from discontinued operations, net of taxes" on Ameren's consolidated statement of income (loss). The net periodic benefit cost includes $7 million and $- million in total net costs for pension benefits and postretirement benefits, respectively, for 2011 which were included in "Income (loss) from discontinued operations, net of taxes" on Ameren's consolidated statement of income (loss). See Note 16 – Divestiture Transactions and Discontinued Operations for additional information on the divestiture.
The current year expected return on plan assets is determined primarily by adjusting the prior-year market-related asset value for current year contributions, disbursements, and expected return, plus 25% of the actual return in excess of (or less than) expected return for the four prior years.
The estimated amounts that will be amortized from regulatory assets and accumulated OCI into net periodic benefit cost in 2014 are as follows:
  
Pension Benefits
 
Postretirement Benefits
  
Ameren(a)
 
Ameren(a)
Regulatory assets:
 
 
 
Prior service cost (credit)
$
(1
)
 
$
(4
)
Net actuarial loss
60

 
9

Accumulated OCI:
 
 
 
Net actuarial (gain) loss
1

 
(2
)
Total
$
60

 
$
3

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Prior service cost is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment. The net actuarial (gain) loss subject to amortization is amortized on a straight-line basis over 10 years.
The Ameren Companies are responsible for their share of the pension and postretirement benefit costs. The following table presents the pension costs and the postretirement benefit costs incurred and included in continuing operations for the years ended December 31, 2013, 2012, and 2011:
  
Pension Costs
 
Postretirement Costs
  
2013
 
2012
 
2011
 
2013
 
2012
 
2011
Ameren Missouri
$
69

 
$
63

 
$
51

 
$
8

 
$
10

 
$
11

Ameren Illinois
41

 
37

 
16

 
—

 
4

 
11

Other
5

 
2

 
3

 
—

 
—

 
1

Ameren(a)
115

 
102

 
70

 
8

 
14

 
23

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
The expected pension and postretirement benefit payments from qualified trust and company funds and the federal subsidy for postretirement benefits related to prescription drug benefits, which reflect expected future service, as of December 31, 2013, are as follows:
  
Pension Benefits
 
Postretirement Benefits
  
Paid from
Qualified
Trust
 
        Paid from
         Company
      Funds
 
        Paid from
         Qualified
      Trust
 
        Paid from
         Company
      Funds
 
        Federal
         Subsidy
2014
$
247

 
$
3

 
$
61

 
$
2

 
$
3

2015
249

 
3

 
63

 
2

 
4

2016
255

 
3

 
66

 
2

 
4

2017
260

 
3

 
69

 
2

 
4

2018
264

 
3

 
72

 
2

 
4

2019 - 2023
1,342

 
14

 
394

 
12

 
19


The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2013, 2012, and 2011:
  
Pension Benefits
 
Postretirement Benefits
  
2013
 
2012
 
2011
 
2013
 
2012
 
2011
Discount rate at measurement date
4.00
%
 
4.50
%
 
5.25
%
 
4.00
%
 
4.50
%
 
5.25
%
Expected return on plan assets
7.50

 
7.75

 
8.00

 
7.25

 
7.50

 
7.75

Increase in future compensation
3.50

 
3.50

 
3.50

 
3.50

 
3.50

 
3.50

Medical cost trend rate (initial)
—

 
—

 
—

 
5.00

 
5.50

 
6.00

Medical cost trend rate (ultimate)
—

 
—

 
—

 
5.00

 
5.00

 
5.00

Years to ultimate rate
—

 
—

 
—

 
—

 
1 year

 
2 years


The table below reflects the sensitivity of Ameren’s plans to potential changes in key assumptions:
  
Pension Benefits
 
Postretirement Benefits
  
Service Cost
and Interest
Cost
 
    Projected
    Benefit
     Obligation
 
    Service Cost
    and Interest
    Cost
 
    Postretirement
      Benefit
       Obligation
0.25% decrease in discount rate
$
(2
)
 
$
109

 
$
—

 
$
32

0.25% increase in salary scale
2

 
17

 
—

 
—

1.00% increase in annual medical trend
—

 
—

 
2

 
40

1.00% decrease in annual medical trend
—

 
—

 
(2
)
 
(37
)

Other
Ameren sponsors a 401(k) plan for eligible employees. The Ameren 401(k) plan covered all eligible employees at December 31, 2013. The plan allowed employees to contribute a portion of their compensation in accordance with specific guidelines. Ameren matched a percentage of the employee contributions up to certain limits. The following table presents the portion of the matching contribution to the Ameren 401(k) plan attributable to the continuing operations for each of the Ameren Companies for the years ended December 31, 2013, 2012, and 2011:
 
2013
 
2012
 
2011
Ameren Missouri
$
16

 
$
16

 
$
16

Ameren Illinois
10

 
9

 
8

Other
1

 
1

 
1

Ameren(a)
27

 
26

 
25

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Stock-Based Compensation
STOCK-BASED COMPENSATION
STOCK-BASED COMPENSATION
Ameren’s long-term incentive plan available for eligible employees is the shareholder-approved 2006 Omnibus Incentive Compensation Plan (2006 Plan), which became effective May 2, 2006. The 2006 Plan provides for a maximum of 4 million common shares to be available for grant to eligible employees and directors. The 2006 Plan awards may be stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, performance share units, cash-based awards, and other stock-based awards.
A summary of nonvested shares at December 31, 2013, and changes during the year ended December 31, 2013, under the 2006 Plan are presented below:
  
Performance Share Units
  
Share
Units
 
Weighted-average
Fair Value per Unit
Nonvested at January 1, 2013
1,192,487

 
$
33.56

Granted(a)
840,482

 
31.19

Unearned or forfeited(b)
(29,730
)
 
31.93

Earned and vested(c)
(784,695
)
 
31.60

Nonvested at December 31, 2013
1,218,544

 
$
33.23

(a)
Includes performance share units (share units) granted to certain executive and nonexecutive officers and other eligible employees in 2013 under the 2006 Plan.
(b)
Includes share units granted in 2011 that were not earned based on performance provisions of the award grants.
(c)
Includes share units granted in 2011 that vested as of December 31, 2013, that were earned pursuant to the provisions of the award grants. Also includes share units that vested due to attainment of retirement eligibility by certain employees and certain employees whose employment terminated on December 2, 2013, with the divestiture of New AER. Actual shares issued for retirement-eligible employees and former New AER subsidiaries' employees will vary depending on actual performance over the three-year measurement period.
Ameren recorded compensation expense of $20 million, $22 million, and $13 million for the years ended December 31, 2013, 2012, and 2011, respectively, and a related tax benefit of $8 million, $8 million and $5 million for the years ended December 31, 2013, 2012, and 2011, respectively. Ameren settled performance share units and restricted shares of $11 million, $11 million, and $4 million for the years ended December 31, 2013, 2012, and 2011. All outstanding restricted shares vested as of the end of 2011. There were no significant compensation costs capitalized related to the performance share units during the years ended December 31, 2013, 2012, and 2011. As of December 31, 2013, total compensation cost of $20 million related to nonvested awards not yet recognized is expected to be recognized over a weighted-average period of 20 months.
Performance Share Units
Performance share units have been granted under the 2006 Plan. A share unit vests and entitles an employee to receive shares of Ameren common stock (plus accumulated dividends) if, at the end of the three-year performance period, certain specified performance or market conditions have been met and the individual remains employed by Ameren. The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the performance goals.
The fair value of each share unit awarded in January 2013 under the 2006 Plan was determined to be $31.19. That amount was based on Ameren's closing common share price of $30.72 at December 31, 2012, and lattice simulations. Lattice simulations are used to estimate expected share payout based on Ameren's total shareholder return for a three-year performance period relative to the designated peer group beginning January 1, 2013. The simulations can produce a greater fair value for the share unit than the applicable closing common share price because they include the weighted payout scenarios in which an increase in the share price has occurred. The significant assumptions used to calculate fair value also included a three-year risk-free rate of 0.36%, volatility of 12% to 21% for the peer group, and Ameren's attainment of a three-year average earnings per share threshold during the performance period.
The fair value of each share unit awarded in January 2012 under the 2006 Plan was determined to be $35.68. That amount was based on Ameren’s closing common share price of $33.13 at December 31, 2011, and lattice simulations. Lattice simulations are used to estimate expected share payout based on Ameren’s total shareholder return for a three-year performance period relative to the designated peer group beginning January 1, 2012. The simulations can produce a greater fair value for the share unit than the applicable closing common share price because they include the weighted payout scenarios in which an increase in the share price has occurred. The significant assumptions used to calculate fair value also included a three-year risk-free rate of 0.41%, volatility of 17% to 31% for the peer group, and Ameren’s attainment of a three-year average earnings per share threshold during the performance period.
Income Taxes
INCOME TAXES
INCOME TAXES
The following table presents the principal reasons why the effective income tax rate differed from the statutory federal income tax rate for the years ended December 31, 2013, 2012, and 2011:
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2013
 
 
 
 
 
Statutory federal income tax rate:
35
 %
 
35
 %
 
35
 %
Increases (decreases) from:
 
 
 
 
 
Depreciation differences
—

 
(1
)
 
—

Amortization of investment tax credit
(1
)
 
—

 
(1
)
State tax
3

 
6

 
4

Other permanent items(a)
1

 
—

 
—

Effective income tax rate
38
 %
 
40
 %
 
38
 %
2012
 
 
 
 
 
Statutory federal income tax rate:
35
 %
 
35
 %
 
35
 %
Increases (decreases) from:
 
 
 
 
 
Depreciation differences
(1
)
 
—

 
(1
)
Amortization of investment tax credit
(1
)
 
(1
)
 
(1
)
State tax
3

 
6

 
5

Reserve for uncertain tax positions
1

 
—

 
—

Other permanent items(a)
—

 
—

 
(1
)
Effective income tax rate
37
 %
 
40
 %
 
37
 %
2011
 
 
 
 
 
Statutory federal income tax rate:
35
 %
 
35
 %
 
35
 %
Increases (decreases) from:
 
 
 
 
 
Depreciation differences
(2
)
 
—

 
(1
)
Amortization of investment tax credit
(1
)
 
(1
)
 
(1
)
State tax
3

 
5

 
4

Reserve for uncertain tax positions
—

 
—

 
1

Tax credits
—

 
—

 
(1
)
Other permanent items(a)
1

 
—

 
—

Effective income tax rate
36
 %
 
39
 %
 
37
 %
(a)
Permanent items are treated differently for book and tax purposes and primarily include non-taxable income related to company-owned life insurance and deductions related to dividends on DRPlus and the 401(k) plan for Ameren, as well as nondeductible expenses related to lobbying and stock issuance costs for Ameren Missouri.
The following table presents the components of income tax expense (benefit) for the years ended December 31, 2013, 2012, and 2011:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
2013
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
136

 
$
(15
)
 
$
(239
)
(b) 
$
(118
)
State
41

 
21

 
(43
)
(b) 
19

Deferred taxes:
 
 
 
 
 
 
 
Federal
64

 
99

 
205

(b) 
368

State
6

 
6

 
36

(b) 
48

Deferred investment tax credits, amortization
(5
)
 
(1
)
 
—

 
(6
)
Total income tax expense (benefit)
$
242

 
$
110

 
$
(41
)
 
$
311

2012
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
(25
)
 
$
(7
)
 
$
72

 
$
40

State
(10
)
 
(3
)
 
23

 
10

Deferred taxes:
 
 
 
 
 
 
 
Federal
248

 
76

 
(120
)
 
204

State
44

 
30

 
(14
)
 
60

Deferred investment tax credits, amortization
(5
)
 
(2
)
 
—

 
(7
)
Total income tax expense (benefit)
$
252

 
$
94

 
$
(39
)
 
$
307

2011
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
3

 
$
(24
)
 
$
15

 
$
(6
)
State
2

 
(4
)
 
—

 
(2
)
Deferred taxes:
 
 
 
 
 
 
 
Federal
129

 
123

 
(39
)
 
213

State
31

 
34

 
(10
)
 
55

Deferred investment tax credits, amortization
(4
)
 
(2
)
 
—

 
(6
)
Total income tax expense (benefit)
$
161

 
$
127

 
$
(34
)
 
$
254

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
These amounts are substantially related to the reversal of unrecognized tax benefits as a result of new IRS guidance related to the deductibility of expenditures to maintain, replace or improve steam or electric power generation property, along with casualty loss deductions for storm damage. They also reflect the increase in deferred tax expense due to available net operating losses.
The Illinois corporate income tax rate increased from 7.3% to 9.5%, as of January 2011. The tax rate is scheduled to decrease to 7.75% in 2015, and it is scheduled to return to 7.3% in 2025. This corporate income tax rate increase in Illinois increased current income tax expense in 2011 by $6 million and $4 million for Ameren and Ameren Illinois, respectively. As a result of this corporate income tax rate increase, accumulated deferred tax balances were revalued, resulting in a decrease in deferred tax expense of $2 million and $3 million for Ameren and Ameren Illinois, respectively, in 2011.
The following table presents the deferred tax assets and deferred tax liabilities recorded as a result of temporary differences at December 31, 2013, and 2012:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
2013
 
 
 
 
 
 
 
Accumulated deferred income taxes, net liability (asset):
 
 
 
 
 
 
 
Plant related
$
2,513

 
$
1,243

 
$
13

 
$
3,769

Regulatory assets, net
74

 
2

 
—

 
76

Deferred employee benefit costs
(74
)
 
(85
)
 
(114
)
 
(273
)
Purchase accounting
—

 
(27
)
 
(1
)
 
(28
)
ARO
(7
)
 
1

 
—

 
(6
)
Other(b)(c)
(17
)
 
(63
)
 
(398
)
 
(478
)
Total net accumulated deferred income tax liabilities (assets)(d)
$
2,489

 
$
1,071

 
$
(500
)
 
$
3,060

2012
 
 
 
 
 
 
 
Accumulated deferred income taxes, net liability (asset):
 
 
 
 
 
 
 
Plant related
$
2,385

 
$
1,145

 
$
20

 
$
3,550

Regulatory assets, net
73

 
—

 
—

 
73

Deferred employee benefit costs
(84
)
 
(102
)
 
(137
)
 
(323
)
Purchase accounting
—

 
(27
)
 
(1
)
 
(28
)
ARO
(7
)
 
1

 
—

 
(6
)
Other(b)
50

 
(77
)
 
(223
)
 
(250
)
Total net accumulated deferred income tax liabilities (assets)(e)
$
2,417

 
$
940

 
$
(341
)
 
$
3,016

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
Includes deferred tax assets related to net operating loss and tax credit carryforwards detailed in the table below.
(c)
Includes total valuation allowances for Ameren, Ameren Missouri, and Ameren Illinois of $7 million, $1 million, and $1 million, respectively, as of December 31, 2013. The state valuation allowances are shown in the table below.
(d)
Includes $20 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2013.
(e)
Includes $26 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2012.
The following table presents the components of deferred tax assets relating to net operating loss carryforwards and tax credit carryforwards at December 31, 2013:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
Net operating loss carryforwards:
 
 
 
 
 
 
 
Federal(b)
$
61

 
$
84

 
$
215

 
$
360

State(c)
3

 
11

 
34

 
48

Total net operating loss carryforwards
$
64

 
$
95

 
$
249

 
$
408

Tax credit carryforwards:
 
 
 
 
 
 
 
Federal(d)
$
12

 
$
—

 
$
76

 
$
88

State(e)
1

 
1

 
32

 
34

State valuation allowance(f)
(1
)
 
(1
)
 
(2
)
 
(4
)
Total tax credit carryforwards
$
12

 
$
—

 
$
106

 
$
118

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
These will begin to expire in 2028.
(c)
These will begin to expire in 2017.
(d)
These will begin to expire in 2029.
(e)
These will begin to expire in 2014.
(f)
This balance increased by $2 million, $- million and $- million for Ameren, Ameren Missouri and Ameren Illinois, respectively, during 2013.
The following table presents the components of deferred tax assets relating to net operating loss carryforwards and tax credit carryforwards at December 31, 2012:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
Net operating loss carryforwards:
 
 
 
 
 
 
 
Federal(b)
$
61

 
$
61

 
$
51

 
$
173

State(c)
3

 
11

 
13

 
27

Total net operating loss carryforwards
$
64

 
$
72

 
$
64

 
$
200

Tax credit carryforwards:
 
 
 
 
 
 
 
Federal(d)
$
11

 
$
—

 
$
75

 
$
86

State(e)
1

 
1

 
23

 
25

State valuation allowance(f)
(1
)
 
(1
)
 
—

 
(2
)
Total tax credit carryforwards
$
11

 
$
—

 
$
98

 
$
109

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
These will begin to expire in 2028
(c)
These will begin to expire in2017.
(d)
These will begin to expire in 2029.
(e)
These began to expire in 2013.
(f)
This balance increased by $1 million, $- million and $1 million for Ameren, Ameren Missouri and Ameren Illinois, respectively, during 2012.
Uncertain Tax Positions
A reconciliation of the change in the unrecognized tax benefit balance during the years ended December 31, 2011, 2012, and 2013, is as follows:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
Unrecognized tax benefits – January 1, 2011
$
164

 
$
56

 
$
26

 
$
246

Increases based on tax positions prior to 2011
15

 
—

 
7

 
22

Decreases based on tax positions prior to 2011
(63
)
 
(41
)
 
(21
)
 
(125
)
Increases based on tax positions related to 2011
13

 
—

 
4

 
17

Changes related to settlements with taxing authorities
(5
)
 
(4
)
 
(1
)
 
(10
)
Decreases related to the lapse of statute of limitations
—

 
—

 
(2
)
 
(2
)
Unrecognized tax benefits – December 31, 2011
$
124

 
$
11

 
$
13

 
$
148

Increases based on tax positions prior to 2012
4

 
—

 
1

 
5

Decreases based on tax positions prior to 2012
(7
)
 
(1
)
 
(5
)
 
(13
)
Increases (decreases) based on tax positions related to 2012
15

 
3

 
(1
)
 
17

Changes related to settlements with taxing authorities
—

 
—

 
—

 
—

Decreases related to the lapse of statute of limitations
—

 
—

 
(1
)
 
(1
)
Unrecognized tax benefits – December 31, 2012
$
136

 
$
13

 
$
7

 
$
156

Increases based on tax positions prior to 2013
—

 
2

 
5

 
7

Decreases based on tax positions prior to 2013
(122
)
 
(16
)
 
(5
)
 
(143
)
Increases based on tax positions related to 2013
16

 
—

 
53

(b) 
69

Changes related to settlements with taxing authorities
—

 
—

 
—

 
—

Increases related to the lapse of statute of limitations
1

 
—

 
—

 
1

Unrecognized tax benefits (detriments) – December 31, 2013
$
31

 
$
(1
)
 
$
60

 
$
90

Total unrecognized tax benefits that, if recognized, would affect the effective tax rates as of December 31, 2011
$
1

 
$
—

 
$
—

 
$
1

Total unrecognized tax benefits (detriments) that, if recognized, would affect the effective tax rates as of December 31, 2012
$
3

 
$
(1
)
 
$
(1
)
 
$
1

Total unrecognized tax benefits that, if recognized, would affect the effective tax rates as of December 31, 2013
$
3

 
$
—

 
$
51

(b) 
$
54


(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
Primarily due to tax positions relating to the New AER divestiture. The income statement impact of this unrecognized tax benefit was included in "Income (loss) from discontinued operations, net of taxes" on Ameren's consolidated statement of income (loss). See Note 16 – Divestiture Transactions and Discontinued Operations for additional information.
The Ameren Companies recognize interest charges (income) and penalties accrued on tax liabilities on a pretax basis as interest charges (income) or miscellaneous expense, respectively, in the statements of income.
A reconciliation of the change in the liability for interest on unrecognized tax benefits during the years ended December 31, 2011, 2012, and 2013, is as follows:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
Liability for interest – January 1, 2011
$
10

 
$
2

 
$
5

 
$
17

Interest income for 2011
(3
)
 
(1
)
 
(7
)
 
(11
)
Interest payment
(1
)
 
—

 
—

 
(1
)
Liability for interest – December 31, 2011
$
6

 
$
1

 
$
(2
)
 
$
5

Interest charges (income) for 2012
2

 
—

 
(1
)
 
1

Liability for interest – December 31, 2012
$
8

 
$
1

 
$
(3
)
 
$
6

Interest charges (income) for 2013
(8
)
 
(1
)
 
4

 
(5
)
Liability for interest – December 31, 2013
$
—

 
$
—

 
$
1

 
$
1


(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
As of December 31, 2011, 2012, and 2013, the Ameren Companies have accrued no amount for penalties with respect to unrecognized tax benefits.
In 2011, a final settlement for the years 2005 and 2006 was reached with the IRS. It resulted in a reduction in uncertain tax liabilities of $39 million, $17 million and $12 million for Ameren, Ameren Missouri and Ameren Illinois, respectively. Ameren’s federal income tax returns for the years 2007 through 2011 are before the Appeals Office of the IRS. Ameren’s federal income tax return for the year 2012 is currently under examination.
It is reasonably possible that a settlement will be reached with the Appeals Office of the IRS in the next twelve months for the years 2007 through 2011. This settlement, primarily related to uncertain tax positions for capitalization versus currently deductible repair expense and research deductions, is expected to result in a decrease in uncertain tax benefits of approximately $20 million and $13 million for Ameren and Ameren Missouri, respectively. In addition, it is reasonably possible that other events will occur during the next twelve months that would cause the total amount of unrecognized tax benefits for the Ameren Companies to increase or decrease. However, the Ameren Companies do not believe any such increases or decreases, including the decrease from the reasonably possible IRS Appeals Office settlement discussed above, would be material to their results of operations, financial position, or liquidity.
In 2013, unrecognized tax benefits related to the deductibility of expenditures to maintain, replace, or improve steam or electric power generation property, along with casualty loss deductions for storm damage, were reduced by $103 million, $95 million and $5 million for Ameren, Ameren Missouri and Ameren Illinois, respectively. This reduction in unrecognized tax benefits did not impact overall income tax expense for the Ameren Companies. However, the liability for interest related to these unrecognized tax benefits has been released. In 2013, Ameren adopted an accounting method change as a result of the recent guidance issued by the IRS, establishing new rules for the amount and timing of the deductions to maintain, replace or improve generation property. In 2014, Ameren expects to adopt an accounting method change as a result of the recent guidance establishing new rules for the amount and timing of casualty loss deductions for storm damage.
State income tax returns are generally subject to examination for a period of three years after filing of the return. The state impact of any federal changes remains subject to examination by various states for a period of up to one year after formal notification to the states. The Ameren Companies do not currently have material state income tax issues under examination, administrative appeals, or litigation.
Ameren Missouri has an uncertain tax position tracker. Under Missouri's regulatory framework, uncertain tax positions do not reduce Ameren Missouri's electric rate base. When an uncertain income tax position liability is resolved, the MoPSC requires, through the uncertain tax position tracker, the creation of a regulatory asset or regulatory liability to reflect the time value, using the weighted-average cost of capital included in each of the electric rate orders in effect before the tax position was resolved, of the difference between the uncertain income tax position liability that was excluded from rate base and the final tax liability. The resulting regulatory asset or liability will affect earnings in the year it is created and then will be amortized over three years beginning on the effective date of new rates established in the next electric rate case.
Related Party Transactions
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS
The Ameren Companies have engaged in, and may in the future engage in, affiliate transactions in the normal course of business. These transactions primarily consist of natural gas and power purchases and sales, services received or rendered, and borrowings and lendings. Transactions between affiliates are reported as intercompany transactions on their financial statements, but are eliminated in consolidation for Ameren’s financial statements. Below are the material related party agreements.
Electric Power Supply Agreements
Capacity Supply Agreements
Ameren Illinois, as an electric load-serving entity, must acquire capacity sufficient to meet its obligations to customers.
In 2010, Ameren Illinois used an RFP process, administered by the IPA, to contract capacity for the period from June 1, 2010, through May 31, 2013. As a winning supplier in this process, in April 2010, Ameren Missouri contracted to supply a portion of Ameren Illinois’ capacity requirements for less than $1 million for the period from June 1, 2010, through May 31, 2013.
In 2012, Ameren Illinois used an RFP process, administered by the IPA, to contract capacity for the period from June 1, 2012, through May 31, 2015. As a winning supplier in this process, in April 2012, Ameren Missouri contracted to supply a portion of Ameren Illinois' capacity requirements for $1 million and $3 million for the 12 months ending May 31, 2014, and 2015, respectively.
Energy Swaps and Energy Products
Ameren Illinois, as an electric load-serving entity, must acquire energy sufficient to meet its obligations to customers.
In 2011, Ameren Illinois used an RFP process, administered by the IPA, to procure energy products that will settle physically from June 1, 2011, through May 31, 2014. Ameren Missouri was among the winning suppliers in the energy product RFP process. In May 2011, Ameren Missouri and Ameren Illinois entered into energy product agreements by which Ameren Missouri agreed to sell and Ameren Illinois agreed to purchase approximately 16,800 megawatthours at approximately $37 per megawatthour during the 12 months ending May 31, 2012, approximately 40,800 megawatthours at approximately $29 per megawatthour during the 12 months ending May 31, 2013, and approximately 40,800 megawatthours at approximately $28 per megawatthour during the 12 months ending May 31, 2014. The energy product agreements between Ameren Missouri and Ameren Illinois for the periods ending May 31, 2012, and May 31, 2013, were for off-peak hours only.
Interconnection and Transmission Agreements
Ameren Missouri and Ameren Illinois are parties to an interconnection agreement for the use of their respective transmission lines and other facilities for the distribution of power. These agreements have no contractual expiration date, but may be terminated by either party with three years’ notice.
Joint Ownership Agreement
ATXI and Ameren Illinois have a joint ownership agreement to construct, own, operate, and maintain certain electric transmission assets in Illinois. Under the terms of this agreement, Ameren Illinois and ATXI are responsible for their applicable share of all costs related to the construction, operation, and maintenance of electric transmission systems. Currently, there are no construction projects or joint ownership of existing assets under this agreement.
In January 2011, ATXI repaid advances for the construction of transmission assets to Ameren Illinois in the amount of $52 million, including $3 million of accrued interest.
In April 2011, ATXI transferred, at cost, all of ATXI’s construction work in progress assets related to a transmission line to Ameren Illinois for $20 million.
Support Services Agreements
Ameren Services provides support services to its affiliates. The costs of support services, including wages, employee benefits, professional services, and other expenses, are based on, or are an allocation of, actual costs incurred. The shared services support agreement can be terminated with respect to a particular affiliate by the mutual agreement of Ameren Services and that affiliate or by either Ameren Services or that affiliate with 60 days' notice before the end of a calendar year.
In addition, Ameren Missouri and Ameren Illinois provide affiliates, primarily Ameren Services, with access to their facilities for administrative purposes. The cost of the rent and facility services are based on, or are an allocation of, actual costs incurred.
Separately, Ameren Missouri and Ameren Illinois provide storm-related and miscellaneous support services to each other on an as-needed basis. 
Transmission Services
Ameren Illinois must take transmission service from MISO for the retail load it serves in the AMIL pricing zone. ATXI is one of the transmission owners in the AMIL pricing zone. Accordingly ATXI receives transmission payments from Ameren Illinois through the MISO billing process.
Money Pool
See Note 4 – Short-term Debt and Liquidity and Note 5 – Long-term Debt and Equity Financings for a discussion of affiliate borrowing arrangements.
Collateral Postings
Under the terms of the Illinois power procurement agreements entered into through RFP processes administered by the IPA, suppliers must post collateral under certain market conditions to protect Ameren Illinois in the event of nonperformance. The collateral postings are unilateral, meaning that only the suppliers would be required to post collateral. Therefore, Ameren Missouri, as a winning supplier in the RFP process, may be required to post collateral. As of December 31, 2013, and 2012, there were no collateral postings required of Ameren Missouri related to the Illinois power procurement agreements.
The following table presents the impact on Ameren Missouri and Ameren Illinois of related party transactions for the years ended December 31, 2013, 2012, and 2011. It is based primarily on the agreements discussed above and the money pool arrangements discussed in Note 4 – Short-term Debt and Liquidity.
Agreement
Income Statement Line Item                    
 
  
 
Ameren
Missouri
 
Ameren
Illinois
Ameren Missouri power supply agreements
Operating Revenues
 
2013
$
3

$
(a)

with Ameren Illinois
 
 
2012
 
(b)

 
(a)

 
 
 
2011
 
2

 
(a)

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2013
 
21

 
1

rent and facility services
 
 
2012
 
19

 
1

 
 
 
2011
 
16

 
2

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2013
 
1

 
3

miscellaneous support services
 
 
2012
 
1

 
(b)

 
 
 
2011
 
5

 
1

Total Operating Revenues
 
 
2013
$
25

$
4

 
 
 
2012
 
20

 
1

 
 
 
2011
 
23

 
3

Ameren Illinois power supply
Purchased Power
 
2013
$
(a)

$
3

agreements with Ameren Missouri
 
 
2012
 
(a)

 
(b)

 
 
 
2011
 
(a)

 
2

Ameren Illinois transmission
Purchased Power
 
2013
 
(a)

 
2

services with ATXI
 
 
2012
 
(a)

 
3

 
 
 
2011
 
(a)

 
3

Total Purchased Power
 
 
2013
$
(a)

$
5

 
 
 
2012
 
(a)

 
3

 
 
 
2011
 
(a)

 
5

Ameren Services support services
Other Operations and
 
2013
$
116

$
93

agreement
Maintenance
 
2012
 
106

 
88

 
 
 
2011
 
114

 
87

Insurance premiums(c)
Other Operations and
 
2013
 
(b)

 
(a)

 
Maintenance
 
2012
 
(b)

 
(a)

 
 
 
2011
 
(b)

 
(a)

Total Other Operations and
 
 
2013
$
116

$
93

Maintenance Expenses
 
 
2012
 
106

 
88

 
 
 
2011
 
114

 
87

Money pool borrowings (advances)
Interest (Charges)
 
2013
$
(b)

$
(b)

 
Income
 
2012
 
(b)

 
(b)

 
 
 
2011
 
—

 
—

(a)
Not applicable.
(b)
Amount less than $1 million.
(c)
Represents insurance premiums paid to Energy Risk Assurance Company, an affiliate for replacement power, property damage, and terrorism coverage.
Commitments And Contingencies
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES
We are involved in legal, tax, and regulatory proceedings before various courts, regulatory commissions, authorities, and governmental agencies with respect to matters that arise in the ordinary course of business, some of which involve substantial amounts of money. We believe that the final disposition of these proceedings, except as otherwise disclosed in these notes to our financial statements, will not have a material adverse effect on our results of operations, financial position, or liquidity.
See also Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 10 – Callaway Energy Center, Note 14 – Related Party Transactions, and Note 16 – Divestiture Transactions and Discontinued Operations in this report.
Callaway Energy Center
The following table presents insurance coverage at Ameren Missouri’s Callaway energy center at December 31, 2013. The property coverage and the nuclear liability coverage must be renewed on April 1 and January 1, respectively, of each year.
Type and Source of Coverage
Maximum Coverages
 
Maximum Assessments
 
Public liability and nuclear worker liability:
 
 
 
 
American Nuclear Insurers
$
375


$
—

 
Pool participation
13,241

(a)  
128

(b)  
 
$
13,616

(c)  
$
128

 
Property damage:
 
 
 
 
Nuclear Electric Insurance Limited
$
2,250

(d)  
$
23

(e)  
European Mutual Association for Nuclear Insurance
500

(f)  
—

 
 
$
2,750

 
$
23

 
Replacement power:
 
 
 
 
Nuclear Electric Insurance Limited
$
490

(g)  
$
9

(e)  
Missouri Energy Risk Assurance Company
$
64

(h)  
$
—

 

(a)
Provided through mandatory participation in an industrywide retrospective premium assessment program.
(b)
Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $375 million in the event of an incident at any licensed United States commercial reactor, payable at $19 million per year.
(c)
Limit of liability for each incident under the Price-Anderson Act liability provisions of the Atomic Energy Act of 1954, as amended. A company could be assessed up to $128 million per incident for each licensed reactor it operates with a maximum of $19 million per incident to be paid in a calendar year for each reactor. This limit is subject to change to account for the effects of inflation and changes in the number of licensed reactors.
(d)
Nuclear Electric Insurance Limited provides $2.25 billion in property damage, decontamination, and premature decommissioning insurance. There is a $1.7 billion sublimit for non-radiation events, of which the top $200 million is a shared limit with other generators purchasing this coverage and includes one free reinstatement.
(e)
All Nuclear Electric Insurance Limited insured plants could be subject to assessments should losses exceed the accumulated funds from Nuclear Electric Insurance Limited.
(f)
European Mutual Association for Nuclear Insurance provides $500 million in excess of the $2.25 billion property coverage and $1.7 billion non-radiation coverage.
(g)
Provides replacement power cost insurance in the event of a prolonged accidental outage at our nuclear energy center. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first eight weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter for a total not exceeding the policy limit of $490 million. Effective April 1, 2013, non-radiation events are sub-limited to $327.6 million.
(h)
Provides replacement power cost insurance in the event of a prolonged accidental outage at our nuclear energy center. The coverage commences after the first 52 weeks of insurance coverage from Nuclear Electric Insurance Limited and is a weekly indemnity of $900,000 for 71 weeks in excess of the $3.6 million per week set forth above. Missouri Energy Risk Assurance Company LLC is an affiliate and has reinsured this coverage with third-party insurance companies. See Note 14 – Related Party Transactions for more information on this affiliate transaction.
The Price-Anderson Act is a federal law that limits the liability for claims from an incident involving any licensed United States commercial nuclear energy center. The limit is based on the number of licensed reactors. The limit of liability and the maximum potential annual payments are adjusted at least every five years for inflation to reflect changes in the Consumer Price Index. The five-year inflationary adjustment was effective September 10, 2013. Owners of a nuclear reactor cover this exposure through a combination of private insurance and mandatory participation in a financial protection pool, as established by the Price-Anderson Act.
Losses resulting from terrorist attacks are covered under Nuclear Electric Insurance Limited’s policies, subject to an industrywide aggregate policy limit of $3.24 billion within a 12-month period for coverage for such terrorist acts.
If losses from a nuclear incident at the Callaway energy center exceed the limits of, or are not covered by insurance, or if coverage is unavailable, Ameren Missouri is at risk for any uninsured losses. If a serious nuclear incident were to occur, it could have a material adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial position, or liquidity.
Leases
We lease various facilities, office equipment, plant equipment, and rail cars under capital and operating leases. The following table presents our lease obligations at December 31, 2013:
 
Total
 
2014
 
2015
 
2016
 
2017
 
2018
 
After 5 Years
Ameren:(a)
 
 
 
 
 
 
 
 
 
 
 
 
 
Minimum capital lease payments(b)
$
556

 
$
32

 
$
33

 
$
33

 
$
33

 
$
32

 
$
393

Less amount representing interest
257

 
27

 
27

 
27

 
27

 
26

 
123

Present value of minimum capital lease payments
$
299

 
$
5

 
$
6

 
$
6

 
$
6

 
$
6

 
$
270

Operating leases(c)
117

 
14

 
13

 
13

 
13

 
13

 
51

Total lease obligations
$
416

 
$
19

 
$
19

 
$
19

 
$
19

 
$
19

 
$
321

Ameren Missouri:
 
 
 
 
 
 
 
 
 
 
 
 
 
Minimum capital lease payments(b)
$
556

 
$
32

 
$
33

 
$
33

 
$
33

 
$
32

 
$
393

Less amount representing interest
257

 
27

 
27

 
27

 
27

 
26

 
123

Present value of minimum capital lease payments
$
299

 
$
5

 
$
6

 
$
6

 
$
6

 
$
6

 
$
270

Operating leases(c)
106

 
11

 
11

 
11

 
12

 
11

 
50

Total lease obligations
$
405

 
$
16

 
$
17

 
$
17

 
$
18

 
$
17

 
$
320

Ameren Illinois:
 
 
 
 
 
 
 
 
 
 
 
 
 
Operating leases(c)
$
7

 
$
2

 
$
1

 
$
1

 
$
1

 
$
1

 
$
1

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
See Properties under Part I, Item 2, and Note 3 – Property and Plant, Net, of this report for additional information.
(c)
Amounts related to certain land-related leases have indefinite payment periods. The annual obligation of $2 million, $1 million and $1 million for Ameren, Ameren Missouri and Ameren Illinois for these items is included in the 2014 through 2018 columns, respectively.
The following table presents total rental expense, included in operating expenses, for the years ended December 31, 2013, 2012, and 2011:
 
2013
 
2012
 
2011
Ameren(a)
$
32

 
$
33

 
$
36

Ameren Missouri
29

 
29

 
29

Ameren Illinois
21

 
19

 
17

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
Other Obligations
To supply a portion of the fuel requirements of our energy centers, we have entered into various long-term commitments for the procurement of coal, natural gas, nuclear fuel, and methane gas. We also have entered into various long-term commitments for purchased power and natural gas for distribution. The table below presents our estimated commitments at December 31, 2013. Ameren’s and Ameren Missouri’s purchased power obligations include a 102-megawatt power purchase agreement with a wind farm operator that expires in 2024. Ameren’s and Ameren Illinois’ purchased power obligations include the Ameren Illinois power purchase agreements entered into as part of the IPA-administered power procurement process. Included in the Other column are minimum purchase commitments under contracts for equipment, design and construction, and meter reading services at December 31, 2013. Ameren's and Ameren Illinois' Other column also include obligations related to IEIMA. In addition, the Other column includes Ameren's and Ameren Missouri's obligations related to energy efficiency programs under the MEEIA as approved by the MoPSC's December 2012 electric rate order. Ameren Missouri expects to incur $48 million in 2014 and $64 million in 2015 for these energy efficiency programs. See Note 2 – Rate and Regulatory Matters for additional information about the IEIMA and MEEIA.
 
Coal
 
Natural
Gas(a)
 
Nuclear
Fuel
 
Purchased
Power(b)
 
Methane
Gas
 
Other
 
Total
Ameren:(c)
 
 
 
 
 
 
 
 
 
 
 
 
 
2014
$
620

 
$
323

 
$
64

 
$
308

 
$
3

 
$
201

 
$
1,519

2015
642

 
179

 
63

 
164

 
4

 
143

 
1,195

2016
664

 
90

 
81

 
78

 
4

 
76

 
993

2017
676

 
45

 
58

 
55

 
4

 
50

 
888

2018
120

 
28

 
57

 
52

 
5

 
51

 
313

Thereafter
125

 
82

 
158

 
635

 
91

 
350

 
1,441

Total
$
2,847

 
$
747

 
$
481

 
$
1,292

 
$
111

 
$
871

 
$
6,349

Ameren Missouri:
 
 
 
 
 
 
 
 
 
 
 
 
 
2014
$
620

 
$
62

 
$
64

 
$
19

 
$
3

 
$
127

 
$
895

2015
642

 
32

 
63

 
19

 
4

 
101

 
861

2016
664

 
19

 
81

 
19

 
4

 
40

 
827

2017
676

 
11

 
58

 
19

 
4

 
26

 
794

2018
120

 
8

 
57

 
19

 
5

 
27

 
236

Thereafter
125

 
28

 
158

 
110

 
91

 
183

 
695

Total
$
2,847

 
$
160

 
$
481

 
$
205

 
$
111

 
$
504

 
$
4,308

Ameren Illinois:
 
 
 
 
 
 
 
 
 
 
 
 
 
2014
$
—

 
$
261

 
$
—

 
$
289

 
$
—

 
$
23

 
$
573

2015
—

 
147

 
—

 
145

 
—

 
24

 
316

2016
—

 
71

 
—

 
59

 
—

 
24

 
154

2017
—

 
34

 
—

 
36

 
—

 
24

 
94

2018
—

 
20

 
—

 
33

 
—

 
24

 
77

Thereafter
—

 
54

 
—

 
525

 
—

 
167

 
746

Total
$
—

 
$
587

 
$
—

 
$
1,087

 
$
—

 
$
286

 
$
1,960

(a)
Includes amounts for generation and for distribution.
(b)
The purchased power amounts for Ameren and Ameren Illinois include 20-year agreements for renewable energy credits that were entered into in December 2010 with various renewable energy suppliers. The agreements contain a provision that allows Ameren Illinois to reduce the quantity purchased in the event that Ameren Illinois would not be able to recover the costs associated with the renewable energy credits.
(c)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
Ameren Illinois has entered into an agreement, through a process administered by the IPA, to purchase power from a repowered unit at the Meredosia energy center designed for permanent carbon dioxide capture and storage, annually over a 20-year period beginning in 2017, for its electric delivery service customers. The agreement is contingent on the parties interested in repowering the unit at the abandoned Meredosia energy center reaching certain milestones related to the construction and commencement of operations of this unit. Ameren will not repower the unit; however, a sale of the unit to a third party is possible. Construction has not begun on the unit at this energy center; therefore, Ameren Illinois’ obligations are not certain at this time and consequently not included in the table above. If the plant is not in service by 2019, Ameren Illinois can terminate the agreement.
Environmental Matters
We are subject to various environmental laws and regulations enforced by federal, state, and local authorities. From the beginning phases of siting and development to the ongoing operation of existing or new electric generation, transmission and distribution facilities and natural gas storage, transmission and distribution facilities, our activities involve compliance with diverse environmental laws and regulations. These laws and regulations address emissions, discharges to water, water usage, impacts to air, land, and water, and chemical and waste handling. Complex and lengthy processes are required to obtain and renew approvals, permits, or licenses for new, existing or modified facilities. Additionally, the use and handling of various chemicals or hazardous materials require release prevention plans and emergency response procedures.
The EPA is developing environmental regulations that will have a significant impact on the electric utility industry. Over time, compliance with these regulations could be particularly costly for certain companies, including Ameren Missouri, that operate coal-fired energy centers. Significant new rules proposed or promulgated include the regulation of CO2 emissions from new energy centers; revised national ambient air quality standards for ozone, fine particulates, SO2, and NOx emissions; the CSAPR, which would have required further reductions of SO2 emissions and NOx emissions from energy centers; a regulation governing management of CCR and coal ash impoundments; the MATS, which require reduction of emissions of mercury, toxic metals, and acid gases from energy centers; revised NSPS for particulate matter, SO2, and NOx emissions from new sources; new effluent standards applicable to waste water discharges from energy centers and new regulations under the Clean Water Act that could require significant capital expenditures, such as modifications to water intake structures or new cooling towers at our energy centers. The EPA is expected to propose CO2 standards for existing fossil fuel-fired electric generation units in the future. These new and proposed regulations, if adopted, may be challenged through litigation, so their ultimate implementation, as well as the timing of any such implementation, is uncertain. Although many details of these future regulations are unknown, the combined effects of the new and proposed environmental regulations may result in significant capital expenditures and increased operating costs over the next five to ten years for Ameren and Ameren Missouri. Compliance with these environmental laws and regulations could be prohibitively expensive or could result in the closure or alteration of the operation of some of our energy centers. Ameren and Ameren Missouri would expect these costs to be recoverable through rates, but the nature and timing of costs, as well as the applicable regulatory framework, could result in regulatory lag.
As of December 31, 2013, Ameren and Ameren Missouri estimate capital expenditure investments of $275 million to $350 million over the next five years to comply with existing environmental regulations. This estimate assumes that CCR will continue to be regulated as nonhazardous. This estimate does not include the impacts of regulations proposed by the EPA under the Clean Water Act, in March 2011, regarding cooling water intake structures or the impact of the effluent standards applicable to steam-electric generating units that the EPA proposed in April 2013, as the technology requirements of these final rules are not yet known. Considerable uncertainty remains in this estimate. The actual amount of capital expenditure investments to comply with existing environmental regulations may vary substantially from the above estimate due to uncertainty as to the precise compliance strategies that will be used and their ultimate cost, among other things.
Ameren Missouri's current environmental compliance plan for air emissions includes burning ultra-low-sulfur coal and installing new or optimizing existing pollution control equipment. Ameren Missouri has two scrubbers at its Sioux energy center, which are used to reduce SO2 emissions and other pollutants. Currently, Ameren Missouri's compliance plan assumes the installation of additional controls including mercury control technology and precipitator upgrades at multiple energy centers within its coal-fired fleet during the next five years. However, Ameren Missouri is currently evaluating its operations and options to determine how to comply with the MATS and other recently finalized or proposed EPA regulations. Additional controls may be necessary, depending upon the resolution of the CSAPR litigation currently pending before the United States Supreme Court or if a new rule replacing CAIR is ultimately adopted, as discussed below. If CSAPR is implemented, Ameren Missouri may be required to install two additional scrubbers within the next ten years.
Environmental compliance costs at some of Ameren Missouri's energy centers could be prohibitive and additional capital investment or continued operations unwarranted. Ameren Missouri's capital expenditures and other costs are subject to MoPSC prudence reviews, which could result in cost disallowances as well as regulatory lag.
The following sections describe the more significant environmental laws and rules that affect or could affect our operations.
Clean Air Act
Both federal and state laws require significant reductions in SO2 and NOx emissions that result from burning fossil fuels. In 2005, the EPA issued regulations with respect to SO2 and NOx emissions (the CAIR). In December 2008, the United States Court of Appeals for the District of Columbia Circuit found various aspects of the law to be unlawful and remanded the CAIR to the EPA for further action, but allowed the CAIR's cap-and-trade programs to remain effective until they are replaced by the EPA. In July 2011, the EPA issued the CSAPR as the CAIR replacement. The CSAPR regulations were vacated by the United States Court of Appeals for the District of Columbia Circuit. The EPA appealed to the United States Supreme Court, and a ruling is expected by June 2014. The EPA will continue to administer the CAIR until a new rule is ultimately adopted or until the United States Supreme Court overturns the decision to vacate the CSAPR.
In December 2011, the EPA issued the MATS under the Clean Air Act, which require emission reductions for mercury and other hazardous air pollutants, such as acid gases, toxic metals, and hydrogen chloride emissions. The MATS do not require a specific control technology to achieve the emission reductions. The MATS will apply to each unit at a coal-fired power plant; however in certain cases, emission compliance can be achieved by averaging emissions from similar electric generating units at the same power plant. Compliance is required by April 2015 or, with a case-by-case extension, by April 2016. Ameren Missouri's Labadie and Meramec energy centers requested and were granted extensions to April 2016 to comply with the MATS.
Emission Allowances
The Clean Air Act created marketable commodities called emission allowances under the acid rain program, the NOx budget trading program, and the CAIR. Ameren Missouri expects to have enough CAIR allowances for 2014 to avoid making external purchases to comply with these programs.
Greenhouse Gas Regulation
In December 2009, the EPA issued its “endangerment finding” under the Clean Air Act, which stated that greenhouse gas emissions, including CO2, endanger human health and welfare and that emissions of greenhouse gases from motor vehicles contribute to that endangerment. In March 2010, the EPA issued a determination that greenhouse gas emissions from stationary sources, such as power plants, would be subject to regulation under the Clean Air Act effective the beginning of 2011. As a result of these actions, we are required to consider the emissions of greenhouse gases in any air permit application.
Recognizing the difficulties presented by regulating at once virtually all emitters of greenhouse gases, the EPA issued the “Tailoring Rule,” which established new higher emission thresholds beginning in January 2011 for regulating greenhouse gas emissions from stationary sources, such as power plants. The rule requires any source that already has an operating permit to have greenhouse-gas-specific provisions added to its permits upon renewal. Currently, all Ameren energy centers have operating permits that have been modified to address greenhouse gas emissions. The Tailoring Rule also provides that if projects performed at major sources or new major sources result in an increase in emissions of greenhouse gases over an applicable annual threshold, such projects could trigger permitting requirements under the NSR programs and the application of best available control technology to control greenhouse gas emissions. In June 2012, the United States Court of Appeals for the District of Columbia Circuit upheld the Tailoring Rule. Industry groups and a coalition of states filed petitions in April 2013 requesting that the United States Supreme Court review the circuit court's decision. In October 2013, the United States Supreme Court granted limited review of one petition, agreeing to consider whether the Clean Air Act authorizes the EPA to regulate emissions of greenhouse gases from stationary sources, including power plants, as a result of its determination to regulate greenhouse gas emissions from motor vehicles. A ruling is expected in 2014.
In June 2013, the Obama administration announced that it had directed the EPA to set CO2 emissions standards for both new and existing power plants. The EPA published proposed regulations in January 2014 that would set revised CO2 emissions standards for new electricity generating units. The proposed standards would establish separate emissions limits for new natural gas-fired plants and new coal-fired plants. In addition, the Obama administration directed the EPA to propose a CO2 emissions standard for existing power plants by June 2014 and to finalize such standard by June 2015. Currently, the Ameren Companies are unable to predict the outcome or impacts of such future regulations.
Future federal and state legislation or regulations that mandate limits on the emission of greenhouse gases may result in significant increases in capital expenditures and operating costs, which, in turn, could lead to increased liquidity needs and higher financing costs. These compliance costs could be prohibitive at some of our energy centers, as the expected return from these investments, at current market prices for energy and capacity, might not justify the required capital expenditures or their continued operation, which could result in the impairment of long-lived assets if costs are not recovered through rates. To the extent that Ameren Missouri requests recovery of these costs through rates, its regulators might delay or deny timely recovery. Mandatory limits on the emission of greenhouse gases could increase costs for our customers or have a material adverse impact on Ameren's and Ameren Missouri's results of operations, financial position, and liquidity. To the extent investments in environmental control technology are reflected and recovered on a timely basis in rate base, Ameren's and Ameren Missouri's earnings may benefit from increased investment in such control technology.
NSR and Clean Air Litigation
In January 2011, the Department of Justice on behalf of the EPA filed a complaint against Ameren Missouri in the United States District Court for the Eastern District of Missouri. The EPA's complaint, as amended in October 2013, alleges that in performing projects at its Rush Island coal-fired energy center in 2007 and 2010, Ameren Missouri violated provisions of the Clean Air Act and Missouri law. In January 2012, the United States District Court granted, in part, Ameren Missouri's motion to dismiss various aspects of the EPA's penalty claims. The EPA's claims for unspecified injunctive relief remain. The trial in this matter is currently scheduled to begin in January 2015. Ameren Missouri believes its defenses are meritorious and will defend itself vigorously. However, there can be no assurances that it will be successful in its efforts.
Ultimate resolution of these matters could have a material adverse impact on the future results of operations, financial position, and liquidity of Ameren and Ameren Missouri. A resolution could result in increased capital expenditures for the installation of pollution control equipment, increased operations and maintenance expenses, and penalties. We are unable to predict the ultimate resolution of these matters or the costs that might be incurred.
Clean Water Act
In March 2011, the EPA announced a proposed rule applicable to cooling water intake structures at existing power plants. The proposed rule would impose standards for reducing the mortality of aquatic organisms impinged on the plant's intake screens or entrained through the plant's cooling water system. All coal-fired, nuclear, and combined cycle energy centers at Ameren Missouri with cooling water systems are subject to this proposed rule. The EPA has agreed to finalize the rule in April 2014. When finalized the final rule could have an adverse effect on our results of operations, financial position, and liquidity if its implementation requires the installation of cooling towers or extensive modifications to the cooling water systems at our energy centers.
In April 2013, the EPA announced its proposal to revise the effluent limitation guidelines applicable to steam electric generating units under the Clean Water Act. Effluent limitation guidelines are national standards for wastewater discharges to surface water that are based on the effectiveness of available control technology. The EPA's proposed rule raised several compliance options that would prohibit effluent discharges of certain, but not all, waste streams and impose more stringent limitations on certain components in wastewater discharges from power plants. If the rule is enacted as proposed, Ameren Missouri would be subject to the revised limitations beginning as early as July 1, 2017, but no later than July 1, 2022. Ameren is reviewing the proposed rule and evaluating its potential impact on operations. The EPA expects to issue final guidelines in April 2014.
Ash Management
In May 2010, the EPA announced proposed new regulations regarding the management and disposal of CCR, which could affect future disposal and handling costs at our energy centers. Those proposed regulations include two options for managing CCRs, under either solid or hazardous waste regulations, but either alternative would allow for some continued beneficial uses, such as recycling of CCR without classifying it as waste. The EPA announced that its April 2013 proposed revisions to the effluent limitations applicable to steam electric generating units would apply to ash ponds and CCR management and that it intended to align this proposal with the CCR rules when finalized. The EPA is expected to issue a final rule in December 2014. Ameren Missouri is currently evaluating all of the proposed regulations to determine whether current management of CCR, including beneficial reuse, and the use of the ash ponds should be altered. Ameren Missouri is evaluating the potential costs associated with compliance with the proposed regulation of CCR impoundments and landfills, which could be material, if such regulations are adopted.
Remediation
We are involved in a number of remediation actions to clean up sites impacted by hazardous substances as required by federal and state law. Such statutes require that responsible parties fund remediation actions regardless of their degree of fault, the legality of original disposal, or the ownership of a disposal site. Ameren Missouri and Ameren Illinois have each been identified by the federal or state governments as a potentially responsible party (PRP) at several contaminated sites.
As of December 31, 2013, Ameren Illinois owned or was otherwise responsible for 44 former MGP sites in Illinois. These sites are in various stages of investigation, evaluation, remediation, and closure. Based on current estimated plans, Ameren Illinois could substantially conclude remediation efforts at most of these sites by 2018. The ICC permits Ameren Illinois to recover remediation and litigation costs associated with its former MGP sites from its electric and natural gas utility customers through environmental adjustment rate riders. To be recoverable, such costs must be prudently incurred. Costs are subject to annual review by the ICC.
As of December 31, 2013, Ameren Missouri has one remaining former MGP site for which remediation is scheduled. Remediation is complete at the other Ameren Missouri former MGP sites. Ameren Missouri does not currently have a rate rider mechanism that permits it to recover from utility customers remediation costs associated with MGP sites.
The following table presents, as of December 31, 2013, the estimated obligation to complete the remediation of these former MGP sites.
  
Estimate
 
Recorded
Liability(a)
  
Low
 
High
 
Ameren
$
278

 
$
338

 
$
278

Ameren Missouri
4

 
5

 
4

Ameren Illinois
274

 
333

 
274

(a)
Recorded liability represents the estimated minimum probable obligations, as no other amount within the range provided a better estimate.
The scope and extent to which these former MGP sites are remediated may increase as remediation efforts continue. Considerable uncertainty remains in these estimates, as many factors can influence the ultimate actual costs, including site specific unanticipated underground structures, the degree to which groundwater is encountered, regulatory changes, local ordinances and site accessibility. The actual costs may vary substantially from these estimates.
Ameren Illinois used an off-site landfill, which Ameren Illinois did not own, in connection with the former operation of an energy center. Ameren Illinois could be required to perform certain maintenance activities associated with that landfill. As of December 31, 2013, Ameren Illinois estimated the obligation related to this site at $0.5 million to $6 million. Ameren Illinois recorded a liability of $0.5 million to represent its estimated minimum obligation for this site, as no other amount within the range was a better estimate. Ameren Illinois is also responsible for the cleanup of some underground storage tanks and a water treatment plant in Illinois. As of December 31, 2013, Ameren Illinois recorded a liability of $0.8 million to represent its estimate of the obligation for these sites.
Ameren Missouri is investigating and addressing two waste sites in Missouri as a result of federal agency mandates. One of the cleanup sites is a former coal tar distillery located in St. Louis, Missouri. In 2008, the EPA issued an administrative order to Ameren Missouri pertaining to this distillery operated by Koppers Company or its predecessor and successor companies. While Ameren Missouri is the current owner of the site, it did not conduct any of the manufacturing operations involving coal tar or its byproducts. Ameren Missouri, along with two other PRPs, is currently performing a site investigation. As of December 31, 2013, Ameren Missouri estimated its obligation at $2 million to $5 million. Ameren Missouri recorded a liability of $2 million to represent its estimated minimum obligation, as no other amount within the range was a better estimate. Ameren Missouri's other active federal agency-mandated cleanup site in Missouri is in Cape Girardeau. Ameren Missouri was a customer of an electrical equipment repair and disposal company that previously operated a facility at this site. A trust was established in the early 1990s by several businesses and governmental agencies to fund the investigation and cleanup of this site, which was completed in 2005. Ameren Missouri anticipates that this trust fund will be sufficient to complete the remaining adjacent off-site cleanup, and therefore, Ameren Missouri believes it has no liability at December 31, 2013, for this site.
Ameren Missouri also has a federal agency mandate to complete an investigation for a site in Illinois. In 2000, the EPA notified Ameren Missouri and numerous other companies, including Solutia, that former landfills and lagoons in Sauget, Illinois, may contain soil and groundwater contamination. These sites are known as Sauget Area 2. From about 1926 until 1976, Ameren Missouri operated an energy center adjacent to Sauget Area 2. Ameren Missouri currently owns a parcel of property that was once used as a landfill. Under the terms of an Administrative Order on Consent, Ameren Missouri joined with other potentially responsible parties to evaluate the extent of potential contamination with respect to Sauget Area 2.
The Sauget Area 2 investigations overseen by the EPA have been completed. In December 2013, the EPA issued its record of decision approving the investigation and the remediation alternatives recommended by the potentially responsible parties. Further negotiation among the potentially responsible parties will determine how to fund the implementation of the EPA approved cleanup remedies. As of December 31, 2013, Ameren Missouri estimated its obligation related to Sauget Area 2 at $0.3 million to $10 million. Ameren Missouri recorded a liability of $0.3 million to represent its estimated minimum obligation, as no other amount within the range was a better estimate.
In December 2012, Ameren Missouri signed an administrative order with the EPA and agreed to investigate soil and groundwater conditions at an Ameren Missouri owned substation in St. Charles, Missouri. As of December 31, 2013, Ameren Missouri estimated the obligation related to the cleanup at $1.6 million to $4.5 million. Ameren Missouri recorded a liability of $1.6 million to represent its estimated minimum obligation for this site, as no other amount within the range was a better estimate.
Our operations or those of our predecessor companies involve the use of, disposal of, and in appropriate circumstances, the cleanup of substances regulated under environmental laws. We are unable to determine whether such practices will result in future environmental commitments or will affect our results of operations, financial position, or liquidity.
Pumped-storage Hydroelectric Facility Breach
In December 2005, there was a breach of the upper reservoir at Ameren Missouri's Taum Sauk pumped-storage hydroelectric energy center. This resulted in significant flooding in the local area, which damaged a state park. The rebuilt Taum Sauk energy center became fully operational in April 2010.
Ameren Missouri had liability insurance coverage for the Taum Sauk incident, subject to certain limits and deductibles. As of December 31, 2013, Ameren Missouri had an insurance receivable balance of $68 million.
In June 2010, Ameren Missouri sued an insurance company that was providing Ameren Missouri with liability coverage on the date of the Taum Sauk incident. In the litigation, filed in the United States District Court for the Eastern District of Missouri, Ameren Missouri claimed that the insurance company breached its duty to indemnify Ameren Missouri for the losses resulting from the incident. In January 2011, the district court ruled that the parties must first pursue alternative dispute resolution and enforced the forum selection clause of their coverage agreement. The forum selection clause requires use of New York law and effectively requires mandatory arbitration. Ameren Missouri appealed the January 2011 ruling to the United States Court of Appeals for the Eighth Circuit. In August 2012, the court of appeals remanded the case to the district court for consideration of whether Missouri public policy voids the forum selection clause. In September 2013, the district court ruled that Missouri public policy does void the forum selection clause.
Separately, in April 2012, Ameren Missouri sued a second insurance company that was providing Ameren Missouri with liability coverage on the date of the Taum Sauk incident. In the April 2012 litigation, which is pending in the United States District Court for the Eastern District of Missouri, Ameren Missouri claimed the insurance company breached its duty to indemnify Ameren Missouri for the losses resulting from the incident. The insurance company filed a motion to compel arbitration, which the district court denied. In April 2013, the United States Court of Appeals for the Eighth Circuit affirmed the district court’s denial of the insurer’s motion and remanded the case to the district court.
Ameren's and Ameren Missouri's results of operations, financial position and liquidity could be adversely affected if Ameren Missouri's remaining liability insurance claims are not paid by insurers.
Asbestos-related Litigation
Ameren, Ameren Missouri and Ameren Illinois have been named, along with numerous other parties, in a number of lawsuits filed by plaintiffs claiming varying degrees of injury from asbestos exposure at our present or former energy centers. Most have been filed in the Circuit Court of Madison County, Illinois. The total number of defendants named in each case varies, with the average number of parties being 82 as of December 31, 2013. Each lawsuit seeks unspecified damages that, if awarded at trial, typically would be shared among the various defendants.
In connection with the divestiture of New AER to IPH, certain agreements related to former Ameren Illinois energy centers were amended to provide that Ameren Illinois will continue to retain asbestos exposure-related liabilities for claims arising or existing from activities prior to its transfer of the ownership of the former Ameren Illinois energy centers to New AER. IPH will be responsible for any asbestos-related claims arising from activities that occur after the effective date of the divestiture. No claims arose solely from activities in the period after the transfer of the energy centers from Ameren Illinois to AER, but before IPH took ownership of New AER.
The following table presents the pending asbestos-related lawsuits filed against the Ameren Companies as of December 31, 2013:
Ameren
 
Ameren
Missouri
 
Ameren
Illinois
 
Total(a)
1
 
47
 
50
 
71

(a)
Total does not equal the sum of the subsidiary unit lawsuits because some of the lawsuits name multiple Ameren entities as defendants.
At December 31, 2013, Ameren, Ameren Missouri and Ameren Illinois had liabilities of $11 million, $5 million, and $6 million, respectively, recorded to represent their best estimate of their obligations related to asbestos claims.
Ameren Illinois has a tariff rider to recover the costs of IP asbestos-related litigation claims, subject to the following terms: 90% of cash expenditures in excess of the amount included in base electric rates are to be recovered from a trust fund that was established when Ameren acquired IP. At December 31, 2013, the trust fund balance was $23 million, including accumulated interest. If cash expenditures are less than the amount in base rates, Ameren Illinois will contribute 90% of the difference to the trust fund. Once the trust fund is depleted, 90% of allowed cash expenditures in excess of base rates will be recovered through charges assessed to customers under the tariff rider. The rider will permit recovery from customers within IP’s historical service territory.
Ameren Illinois Municipal Taxes
Ameren Illinois received tax liability notices from the city of O'Fallon, Illinois, relating to prior-period electric and natural gas municipal taxes. The city alleges that Ameren Illinois failed to collect prior-period taxes from more than 2,400 accounts, primarily in annexed areas, for the period 2004 through 2012. In July 2013, the O’Fallon city administrator issued an order stating that Ameren Illinois was liable to the city of O’Fallon for $4 million. In August 2013, Ameren Illinois filed an appeal and a stay of the O’Fallon city administrator’s order to the St. Clair County Circuit Court. In addition, in December 2012, the city of Peoria issued a tax liability notice alleging that Ameren Illinois failed to collect prior-period municipal taxes from certain accounts. In September 2013, a hearing officer issued an order stating that Ameren Illinois was liable to the city of Peoria for $0.5 million. Ameren Illinois filed an appeal and a stay of the order to the Peoria County Circuit Court. Ameren Illinois believes its defenses to the allegations are meritorious and will defend itself vigorously. As of December 31, 2013, Ameren Illinois estimated its obligation at $1 million to $5 million. Ameren Illinois recorded a liability of $1 million to represent its estimated minimum obligation to the city of O'Fallon and the city of Peoria, as no other amount within the range was a better estimate.
In addition, at the end of 2012, five other cities issued tax liability notices alleging that Ameren Illinois failed to collect prior-period taxes from certain accounts. At this time, it is premature in Ameren Illinois' review of the additional notices received at the end of 2012 to reasonably estimate any likelihood of loss.
Divestiture Transactions and Discontinued Operations (Notes)
DIVESTITURE TRANSACTIONS AND DISCONTINUED OPERATIONS
NOTE 16 – DIVESTITURE TRANSACTIONS AND DISCONTINUED OPERATIONS
Transaction Agreement with IPH
On December 2, 2013, Ameren completed the divestiture of New AER to IPH, in accordance with the transaction agreement between Ameren and IPH dated March 14, 2013, as amended by a letter agreement entered into by Ameren and IPH on December 2, 2013. IPH acquired all of the outstanding limited liability interests in New AER, which was a newly created, wholly owned subsidiary of AER. Prior to the closing, AER effected a reorganization that, among other things, transferred substantially all of its assets and liabilities to New AER, other than (i) any outstanding debt obligations of AER to Ameren or its other subsidiaries, except for certain intercompany balances discussed below; (ii) the assets and liabilities associated with Genco’s Meredosia and Hutsonville energy centers; (iii) the obligations relating to Ameren's single-employer pension and postretirement benefit plans; and (iv) the deferred income tax assets and liabilities associated with Ameren's ownership of these retained assets and liabilities.
Ameren retained certain pension and postretirement benefit obligations associated with current and former employees of AER, with the exception of the pension and postretirement benefit obligations associated with current and former employees of EEI, which were assumed by IPH. Ameren retained the Meredosia and Hutsonville energy centers, including their AROs, which totaled $31 million as of December 31, 2013. These energy centers were abandoned and had an immaterial property and plant asset balance as of December 31, 2013. All other AROs associated with AER were assumed by New AER or by Rockland Capital, the third-party buyer of the Grand Tower energy center, as discussed below.
Upon the IPH transaction agreement closing, all intercompany agreements and debt that existed between New AER and its subsidiaries, on the one hand, and Ameren and its non-New AER affiliates, on the other hand, with the exception of certain agreements, such as supply obligations to Ameren Illinois, a note from Marketing Company to Ameren relating to cash collateral that remained outstanding at closing, Genco money pool advances and certain New AER subsidiary money pool borrowings, were either retained or cancelled by Ameren, without any cost or obligation to IPH or New AER and its subsidiaries. Immediately prior to the closing of the divestiture, the money pool borrowings through which Ameren provided cash collateral to Marketing Company were converted to a note payable to Ameren, which is payable, with interest, 24 months after closing or sooner as cash collateral requirements are reduced. The balance of the note was $18 million at December 31, 2013, and is reflected on Ameren's consolidated balance sheet in "Other assets."
Pursuant to the transaction agreement, as amended by the December 2, 2013 letter agreement, Ameren caused $235 million of cash to be retained at New AER immediately prior to closing, which included amounts previously paid to Genco for the sale of the Elgin, Gibson City, and Grand Tower energy centers to Medina Valley as well as additional amounts retained at Genco, AERG, and Marketing Company. Within 120 days after the closing of the divestiture, a working capital adjustment will be finalized, which may result in a cash payment from Ameren to IPH or from IPH to Ameren. Ameren received no cash proceeds as a result of the divestiture of New AER. Pursuant to the transaction agreement, as amended, Ameren is obligated to pay up to $39 million for certain contingent liabilities. Of these liabilities, $29 million are included in "Other deferred credits and liabilities" and $10 million are included in "Accounts and wages payable" on Ameren's December 31, 2013 consolidated balance sheet.
As a condition to the transaction agreement, Genco exercised the amended put option agreement for the sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Medina Valley. In October 2013, Genco completed the sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Medina Valley, receiving total payments of $137.5 million. The third-party sale of these energy centers to Rockland Capital was completed on January 31, 2014 and is discussed below.
Sale of Gas-fired Energy Centers
Prior to entry into the transaction agreement with IPH, Genco entered into a put option agreement, as amended, with Medina Valley. This agreement gave Genco the option to sell to Medina Valley the Elgin, Gibson City, and Grand Tower gas-fired energy centers for the fair market value of the energy centers, as determined by three independent appraisers. Genco exercised its option, and in October 2013 completed its sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Medina Valley for $137.5 million, which was the fair value of the gas-fired energy centers as determined by the three independent appraisers.
The transaction agreement with IPH, as amended, provides that if the Elgin, Gibson City, and Grand Tower gas-fired energy centers are subsequently sold by Medina Valley and if Medina Valley receives additional proceeds from such sale, Medina Valley will pay Genco any proceeds from such sale, net of taxes and other expenses, in excess of the $137.5 million previously paid to Genco.
On January 31, 2014, Medina Valley completed the sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital for a total purchase price of $168 million, before consideration of a net working capital adjustment. The agreement with Rockland Capital required $17 million of the purchase price to be held in escrow until the two-year anniversary of the closing of the sale to fund certain indemnity obligations, if any, of Medina Valley. The net working capital adjustment will be finalized within 120 days after the January 31, 2014 closing date. As a result, pending final resolution of the net working capital adjustment, taxes, and other expenses, Medina Valley expects to pay Genco any remaining portion of the escrow balance on January 31, 2016. Ameren will not record a gain from its sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers.
Discontinued Operations Presentation
As of March 14, 2013, Ameren determined that New AER and the Elgin, Gibson City, and Grand Tower gas-fired energy centers qualified for discontinued operations presentation. In addition, effective December 2, 2013, coinciding with the completion of the divestiture of New AER to IPH, Ameren determined that the Meredosia and Hutsonville energy centers had been abandoned. Ameren is prohibited from operating these energy centers through December 31, 2020, as a provision of the Illinois Pollution Control Board's November 2013 order granting IPH a variance of the MPS. As a result, Ameren determined the Meredosia and Hutsonville energy centers qualified for discontinued operations presentation as of December 2, 2013.
New AER and the Elgin, Gibson City, Grand Tower, Meredosia, and Hutsonville energy centers have been classified collectively in Ameren’s consolidated financial statements as discontinued operations for all periods presented in this report. The disposal groups have been aggregated in the disclosures below. The following table presents the components of discontinued operations in Ameren's consolidated statement of income (loss) for the years ended December 31, 2013, 2012 and 2011:
 
Year ended
 
2013
 
2012
 
2011
Operating revenues
$
1,037

 
$
1,047

 
$
1,358

Operating expenses
(1,207
)
(a) 
(3,474
)
(b) 
(1,150
)
Operating income (loss)
(170
)
 
(2,427
)
 
208

Other income (loss)
(1
)
 
—

 
1

Interest charges
(39
)
 
(56
)
 
(64
)
Income (loss) before income taxes
(210
)
 
(2,483
)
 
145

Income tax (expense) benefit
(13
)
 
987

 
(56
)
Income (loss) from discontinued operations, net of taxes
$
(223
)
 
$
(1,496
)
 
$
89

(a)
Includes a $201 million pretax loss on disposal relating to the New AER divestiture.
(b)
Includes a noncash pretax asset impairment charge of $628 million to reduce the carrying value of AERG’s Duck Creek energy center to its estimated fair value under held and used accounting guidance. In addition, includes a noncash pretax asset impairment charge of $1.95 billion to reduce the carrying values of all the AER coal and natural gas-fired energy centers, except the Joppa coal-fired energy center, to their estimated fair values, under held and used accounting guidance, as a result of the decision in December 2012 that Ameren intended to exit the Merchant Generation business.
Upon completion of the divestiture of New AER, Ameren finalized its loss on disposal. Ameren received no cash proceeds from IPH for the divestiture of New AER. Ameren recorded a pretax charge to earnings related to the New AER divestiture of $201 million for the year ended December 31, 2013. The loss was recorded in “Operating expenses” within the components of the discontinued operations statement of income (loss). The ultimate loss on disposal may differ as a result of the finalization of the working capital adjustment within 120 days of close.
In 2013, Ameren adjusted the accumulated deferred income taxes on its consolidated balance sheet to reflect the excess of tax basis over financial reporting basis of its stock investment in AER. This change in basis resulted in a discontinued operations deferred tax expense of $99 million, which was partially offset by the expected tax benefits of $86 million related to the pretax loss from discontinued operations including the loss on disposal, during the year ended December 31, 2013. The final tax basis of the AER disposal group and the related tax benefit resulting from the transaction agreement with IPH are dependent upon the resolution of tax matters under IRS audit, including the adoption of recently issued guidance from the IRS related to tangible property repairs and other matters. As a result, tax expense and benefits ultimately realized in discontinued operations may differ materially from those recorded as of December 31, 2013.
As the Elgin, Gibson City, and Grand Tower gas-fired energy center disposal group continued to meet the discontinued operations criteria at December 31, 2013, Ameren evaluated whether any impairment existed by comparing the disposal group’s carrying value to the estimated fair value of the disposal group, less cost to sell. In December 2012, Ameren recorded a noncash long-lived asset impairment charge to reduce the carrying value of AER’s energy centers, including the Elgin, Gibson City, and Grand Tower gas-fired energy centers, to their estimated fair values under the accounting guidance for held and used assets. Ameren did not record any additional impairment relating to the Elgin, Gibson City, and Grand Tower energy centers for the year ended December 31, 2013. As discussed above, on January 31, 2014, Medina Valley completed the sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital for a total purchase price of $168 million, before consideration of a net working capital adjustment. Ameren will not recognize a gain from the third party sale to Rockland Capital for any value in excess of its $137.5 million carrying value for this disposal group since any excess amount that Medina Valley may receive, net of taxes and other expenses, over the carrying value, will ultimately be paid to Genco pursuant to the transaction agreement with IPH.
Long-lived Asset Impairments
New AER and the Elgin, Gibson City, and Grand Tower energy centers were impaired under held and used accounting guidance in 2012 and the Meredosia and Hutsonville energy centers were impaired under held and used accounting guidance in 2011. The 2012 and 2011 impairments are discussed below.
As a result of the December 2012 decision that Ameren intended to, and it was probable that it would, exit the Merchant Generation segment before the end of the Merchant Generation long-lived assets' previously estimated useful lives, Ameren determined that estimated undiscounted cash flows during the period in which it expected to continue to own certain energy centers would be insufficient to recover the carrying value of those energy centers. Accordingly, Ameren recorded a noncash pretax impairment charge of $1.95 billion in the fourth quarter of 2012 to reduce the carrying values of all of the Merchant Generation's coal and natural gas-fired energy centers, except the Joppa coal-fired energy center, to their estimated fair values. The estimated undiscounted cash flows of the Joppa coal-fired energy center exceeded its carrying value; therefore, the Joppa coal-fired energy center was unimpaired.
In early 2012, the observable market price for power for delivery in that year and in future years in the Midwest sharply declined below 2011 levels, primarily because of declining natural gas prices and the impact of the stay of the CSAPR. As a result of this sharp decline in the market price of power and the related impact on electric margins, Genco decelerated the construction of two scrubbers at its Newton energy center in February 2012. The sharp decline in the market price of power in early 2012 and the related impact on electric margins, as well as the deceleration of construction of Genco's Newton energy center scrubber project, caused Ameren to evaluate, during the first quarter of 2012, whether the carrying values of Merchant Generation coal-fired energy centers were recoverable. AERG's Duck Creek energy center's carrying value exceeded its estimated undiscounted future cash flows. As a result, Ameren recorded a noncash pretax asset impairment charge of $628 million to reduce the carrying value of that energy center to its estimated fair value during the first quarter of 2012.
In December 2011, Genco ceased operations at its Meredosia and Hutsonville energy centers. As a result, Ameren recorded a noncash pretax asset impairment charge of $26 million to reduce the carrying value of the Meredosia and Hutsonville energy centers to their estimated fair values and a $4 million impairment for materials and supplies.
Key assumptions used in the determination of estimated undiscounted cash flows for the 2012 and 2011 long-lived assets tested for impairment under held and used accounting guidance discussed above included forward price projections for energy and fuel costs, the expected life or duration of ownership of the long-lived assets, environmental compliance costs and strategies, and operating costs. Those same cash flow assumptions, along with a discount rate and terminal year earnings multiples, were used to estimate the fair value of each energy center. These assumptions are subject to a high degree of judgment and complexity. The fair value estimate of these long-lived assets was based on a combination of the income approach, which considers discounted cash flows, and the market approach, which considers market multiples for similar assets within the electric generation industry. The fair value estimate was determined using observable inputs and significant unobservable inputs, which are Level 3 inputs as defined by accounting guidance for fair value measurements.
The following table presents the carrying amounts of the components of assets and liabilities segregated on Ameren's consolidated balance sheets as discontinued operations at December 31, 2013, and 2012:
 
December 31, 2013
 
December 31, 2012
Assets of discontinued operations
 
 
 
Cash and cash equivalents
$
—

 
$
25

Accounts receivable and unbilled revenue
5

 
102

Materials and supplies
5

 
135

Mark-to-market derivative assets
—

 
102

Property and plant, net
142

 
748

Accumulated deferred income taxes, net(a)
13

 
395

Other assets
—

 
104

Total assets of discontinued operations
$
165

 
$
1,611

Liabilities of discontinued operations
 
 
 
Accounts payable and other current obligations
$
5

 
$
141

Mark-to-market derivative liabilities
—

 
63

Long-term debt, net
—

 
824

Asset retirement obligations(b)
40

 
97

Pension and other postretirement benefits
—

 
40

Other liabilities
—

 
28

Total liabilities of discontinued operations
$
45

 
$
1,193

Accumulated other comprehensive income (c)
$
—

 
$
19

Noncontrolling interest(d)
$
—

 
$
8

(a)
The December 31, 2013 balance primarily consists of deferred income tax assets related to the abandoned Meredosia and Hutsonville energy centers.
(b)
Includes AROs associated with the abandoned Meredosia and Hutsonville energy centers of $31 million and $26 million at December 31, 2013, and 2012, respectively.
(c)
Accumulated other comprehensive income related to discontinued operations included in “Accumulated other comprehensive loss” on Ameren’s December 31, 2012, consolidated balance sheet. This balance related to New AER assets and liabilities that were realized or removed from Ameren’s consolidated balance sheet either before or at the December 2, 2013 closing of the New AER divestiture.
(d)
The 20% ownership interest of EEI not owned by Ameren was included in “Noncontrolling interests” on Ameren’s December 31, 2012, consolidated balance sheet. This noncontrolling interest was removed from Ameren’s consolidated balance sheet at the December 2, 2013 closing of the New AER divestiture.
Ameren has continuing transactions with New AER. Ameren Illinois has power supply agreements with Marketing Company, which are a result of the power procurement process in Illinois administered by the IPA, as required by the Illinois Public Utilities Act. Ameren Illinois continues to purchase power and to purchase trade receivables as required by Illinois law. Ameren Illinois and ATXI continue to sell transmission services to Marketing Company. Also, the transaction agreement requires Ameren (parent) to maintain certain guarantees discussed below. Immediately prior to the transaction agreement closing, the money pool borrowings through which Ameren provided cash collateral to Marketing Company were converted to a note payable to Ameren, which is payable, with interest, 24 months after closing or sooner as cash collateral requirements are reduced. Also, within 120 days after closing, a working capital adjustment will be finalized, which may result in a cash payment from Ameren to New AER or from New AER to Ameren. Ameren has determined that the continuing cash flows generated by these arrangements are not significant and, accordingly, are not deemed to be direct cash flows of the divested business. Additionally, these arrangements do not provide Ameren with the ability to significantly influence the operating results of New AER. Ameren will not have significant continuing involvement with or material cash flows from the Elgin, Gibson City, or Grand Tower energy centers after their sale.
Ameren Guarantees
Upon the divestiture of New AER, the transaction agreement between Ameren and IPH requires Ameren (parent) to maintain its financial obligations with respect to all credit support provided to New AER as of the closing date of such divestiture. Ameren must also provide such additional credit support as required by contracts entered into prior to the closing date, in each case for up to 24 months after the closing. IPH shall indemnify Ameren for any payments Ameren makes pursuant to these credit support obligations if the counterparty does not return the posted collateral to Ameren. IPH's indemnification obligation is secured by certain AERG and Genco assets. In addition, Dynegy has provided a limited guarantee of $25 million to Ameren (parent) pursuant to which Dynegy will, among other things, guarantee IPH's indemnification obligations for a period of up to 24 months after the closing.
At December 31, 2013, Ameren had a total of $190 million in guarantees outstanding, which included:
•
$176 million related to guarantees supporting Marketing Company for physically and financially settled power transactions with its counterparties that were in place at the December 2, 2013 closing of the divestiture, as well as for Marketing Company's clearing broker and other service agreements. If Marketing Company did not fulfill its obligations to these counterparties who had active open positions as of December 31, 2013, Ameren would have been required under its guarantees to provide $6 million to the counterparties.
•
$14 million related to requirements for leasing agreements and potential environmental obligations.
Additionally, at December 31, 2013, Ameren had issued letters of credit totaling $11 million as credit support on behalf of New AER.
Ameren has not recorded a reserve for these contingent obligations because it does not believe a payment for any of these guarantees is probable as of December 31, 2013.
Segment Information
SEGMENT INFORMATION
SEGMENT INFORMATION
Ameren has two reportable segments: Ameren Missouri and Ameren Illinois. The Ameren Missouri segment for both Ameren and Ameren Missouri includes all the operations of Ameren Missouri’s business as described in Note 1 – Summary of Significant Accounting Policies. The Ameren Illinois segment for both Ameren and Ameren Illinois consists of all of the operations of Ameren Illinois as described in Note 1 – Summary of Significant Accounting Policies. The category called Other primarily includes Ameren parent company activities, Ameren Services, and ATXI. The Other category also includes certain corporate activities previously included in the Merchant Generation segment. See Note 16 – Divestiture Transactions and Discontinued Operations for additional information.
The following table presents information about the reported revenues and specified items reflected in Ameren’s net income attributable to Ameren Corporation from continuing operations for the years ended December 31, 2013, 2012, and 2011, and total assets in continuing operations as of December 31, 2013, 2012, and 2011.
Ameren
 
Ameren
Missouri
 
Ameren
Illinois
 
Other
 
Intersegment
Eliminations
 
Consolidated
 
2013
 
 
 
 
 
 
 
 
 
 
External revenues
$
3,516

 
$
2,307

 
$
15

 
$
—

 
$
5,838

 
Intersegment revenues
25

 
4

 
2

 
(31
)
 
—

 
Depreciation and amortization
454

 
243

 
9

 
—

 
706

 
Interest and dividend income
27

 
2

 
1

 
—

 
30

 
Interest charges
210

 
143

 
45

 
—

 
398

 
Income taxes (benefit)
242

 
110

 
(41
)
 
—

 
311

 
Net income (loss) attributable to Ameren Corporation from continuing operations
395

 
160

 
(43
)
 
—

 
512

 
Capital expenditures
648

 
701

 
30

(a) 
—

 
1,379

 
Total assets
12,904

 
7,454

 
752

 
(233
)
 
20,877

(b) 
2012
 
 
 
 
 
 
 
 
 
 
External revenues
$
3,252

 
$
2,524

 
$
5

 
$
—

 
$
5,781

 
Intersegment revenues
20

 
1

 
3

 
(24
)
 
—

 
Depreciation and amortization
440

 
221

 
12

 
—

 
673

 
Interest and dividend income
32

 
—

 
—

 
—

 
32

 
Interest charges
223

 
129

 
40

 
—

 
392

 
Income taxes (benefit)
252

 
94

 
(39
)
 
—

 
307

 
Net income (loss) attributable to Ameren Corporation from continuing operations
416

 
141

 
(41
)
 
—

 
516

 
Capital expenditures
595

 
442

 
26

(a) 
—

 
1,063

 
Total assets
13,043

 
7,282

 
1,228

 
(934
)
 
20,619

(b) 
2011
 
 
 
 
 
 
 
 
 
 
External revenues
$
3,360

 
$
2,784

 
$
4

 
$
—

 
$
6,148

 
Intersegment revenues
23

 
3

 
3

 
(29
)
 
—

 
Depreciation and amortization
408

 
215

 
20

 
—

 
643

 
Interest and dividend income
30

 
1

 
—

 
—

 
31

 
Interest charges
209

 
136

 
42

 
—

 
387

 
Income taxes (benefit)
161

 
127

 
(34
)
 
—

 
254

 
Net income (loss) attributable to Ameren Corporation from continuing operations
287

 
193

 
(49
)
 
—

 
431

 
Capital expenditures
550

 
351

 
(20
)
(a) 
—

 
881

 
Total assets
12,757

 
7,213

 
1,211

 
(1,179
)
 
20,002

(b) 
.
(a)
Includes the elimination of intercompany transfers.
(b)
Excludes total assets from discontinued operations of $165 million, $1,611 million, and $3,721 million as of December 31, 2013, 2012, and 2011, respectively.
Selected Quarterly Information
SELECTED QUARTERLY INFORMATION
SELECTED QUARTERLY INFORMATION (Unaudited) (In millions, except per share amounts)
Ameren
2013
 
 
2012
Quarter ended (a)
March 31
 
June 30
 
September 30
 
December 31
 
 
March 31
 
June 30
 
September 30
 
December 31
Operating revenues
$
1,475

 
$
1,403

 
$
1,638

 
$
1,322

 
 
$
1,412

 
$
1,402

 
$
1,709

 
$
1,258

Operating income
185

 
261

 
567

 
171

 
 
159

 
347

 
570

 
112

Net income (loss)(b)
(143
)
 
96

 
304

 
38

 
 
(403
)
 
210

 
374

 
(1,155
)
Net income attributable to Ameren Corporation – continuing operations
$
54

 
$
105

 
$
305

 
$
48

 
 
$
38

 
$
164

 
$
302

 
$
12

Net income (loss) attributable to Ameren Corporation – discontinued operations (b)
(199
)
 
(10
)
 
(3
)
 
(11
)
 
 
(441
)
 
47

 
72

 
(1,168
)
Net income (loss) attributable to Ameren Corporation
$
(145
)
 
$
95

 
$
302

 
$
37

 
 
$
(403
)
 
$
211

 
$
374

 
$
(1,156
)
Earnings per common share – basic – continuing operations
$
0.22

 
$
0.44

 
$
1.26

 
$
0.19

 
 
$
0.16

 
$
0.67

 
$
1.25

 
$
0.05

Earnings (loss) per common share – basic – discontinued operations
(0.82
)
 
(0.05
)
 
(0.01
)
 
(0.04
)
 
 
(1.82
)
 
0.20

 
0.29

 
(4.81
)
Earnings (loss) per common share – basic
$
(0.60
)
 
$
0.39

 
$
1.25

 
$
0.15

 
 
$
(1.66
)
 
$
0.87

 
$
1.54

 
$
(4.76
)
Earnings per common share – diluted – continuing operations
$
0.22

 
$
0.44

 
$
1.25

 
$
0.19

 
 
$
0.16

 
$
0.67

 
$
1.25

 
$
0.05

Earnings (loss) per common share – diluted – discontinued operations
(0.82
)
 
(0.05
)
 
(0.01
)
 
(0.04
)
 
 
(1.82
)
 
0.20

 
0.29

 
(4.81
)
Earnings (loss) per common share – diluted
$
(0.60
)
 
$
0.39

 
$
1.24

 
$
0.15

 
 
$
(1.66
)
 
$
0.87

 
$
1.54

 
$
(4.76
)
(a)
The sum of quarterly amounts, including per share amounts, may not equal amounts reported for year-to-date periods. This is due to the effects of rounding and to changes in the number of weighted-average shares outstanding each period.
(b)
Includes pretax asset impairment charge of $2.6 billion recorded in discontinued operations during the year ended December 31, 2012. See Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, for additional information.
Ameren Missouri Quarter ended
 
Operating
revenues
 
Operating
income
 
Net income
(loss)
 
Net income (loss)
available
to common
stockholder
March 31, 2013
 
$
796

 
$
111

 
$
41

 
$
40

March 31, 2012
 
691

 
78

 
22

 
21

June 30, 2013
 
889

 
179

 
85

 
84

June 30, 2012
 
844

 
269

 
144

 
143

September 30, 2013
 
1,093

 
417

 
239

 
238

September 30, 2012
 
1,064

 
429

 
237

 
236

December 31, 2013
 
763

 
96

 
33

 
33

December 31, 2012
 
673

 
69

 
16

 
16


Ameren Illinois Quarter ended
 
Operating
revenues
 
Operating
income
 
Net income
 
Net income
available
to common
stockholder
March 31, 2013
 
$
684

 
$
85

 
$
32

 
$
31

March 31, 2012
 
724

 
89

 
28

 
27

June 30, 2013
 
516

 
87

 
32

 
31

June 30, 2012
 
564

 
86

 
33

 
32

September 30, 2013
 
547

 
158

 
77

 
77

September 30, 2012
 
648

 
151

 
71

 
71

December 31, 2013
 
564

 
85

 
22

 
21

December 31, 2012
 
589

 
51

 
12

 
11

Schedule I - Condensed Financial Information Of Parent
Condensed Financial Information Of Parent
SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED STATEMENT OF INCOME (LOSS) AND COMPREHENSIVE INCOME (LOSS)
For the Years Ended December 31, 2013, 2012 and 2011
(In millions)
2013
 
2012
 
2011
Operating revenues
$
—

 
$
—

 
$
—

Operating expenses
26

 
17

 
13

Operating loss
(26
)
 
(17
)
 
(13
)
Equity in earnings of subsidiaries
546

 
546

 
464

Interest income from affiliates
3

 
3

 
5

Miscellaneous expense
5

 
4

 
4

Interest charges
42

 
39

 
41

Income tax (benefit)
(36
)
 
(27
)
 
(20
)
Net Income Attributable to Ameren Corporation – Continuing Operations
512

 
516

 
431

Net Income (Loss) Attributable to Ameren Corporation – Discontinued Operations
(223
)
 
(1,490
)
 
88

Net Income (Loss) Attributable to Ameren Corporation
$
289

 
$
(974
)
 
$
519

 
 
 
 
 
 
Net Income Attributable to Ameren Corporation – Continuing Operations
$
512

 
$
516

 
$
431

Other Comprehensive Income (Loss), Net of Taxes:
 
 
 
 
 
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $16, $(6), and $(14), respectively
30

 
(8
)
 
(19
)
Comprehensive Income from Continuing Operations Attributable to Ameren Corporation
542

 
508

 
412

Net Income (Loss) Attributable to Ameren Corporation – Discontinued Operations
(223
)
 
(1,490
)
 
88

Other Comprehensive Income (Loss) from Discontinued Operations, Net of Income Taxes
(19
)
 
50

 
(14
)
Comprehensive Income (Loss) from Discontinued Operations Attributable to Ameren Corporation
(242
)
 
(1,440
)
 
74

Comprehensive Income (Loss) Attributable to Ameren Corporation
$
300

 
$
(932
)
 
$
486

SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED BALANCE SHEET
(In millions)
December 31, 2013
 
December 31, 2012
Assets:
 
 
 
Cash and cash equivalents
$
11

 
$
23

Advances to money pool
334

 
316

Accounts and notes receivable – affiliates
27

 
31

Miscellaneous accounts and notes receivable
125

 
—

Other current assets
42

 
49

Total current assets
539

 
419

Investments in subsidiaries – continuing operations
6,336

 
6,315

Investments in subsidiaries – discontinued operations
(5
)
 
(353
)
Note receivable - affiliates
51

 
462

Accumulated deferred income taxes, net
623

 
210

Other non-current assets
141

 
110

Total assets
$
7,685

 
$
7,163

Liabilities and Stockholders’ Equity:
 
 
 
Current maturities of long-term debt
$
425

 
$
—

Short-term debt
368

 
—

Accounts payable
119

 
3

Accounts payable – affiliates
4

 
10

Other current liabilities
20

 
30

Total current liabilities
936

 
43

Long-term debt
—

 
424

Other deferred credits and liabilities
205

 
80

Total liabilities
1,141

 
547

Commitments and Contingencies
 
 
 
Stockholders’ Equity:
 
 
 
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 242.6
2

 
2

Other paid-in capital, principally premium on common stock
5,632

 
5,616

Retained earnings
907

 
1,006

Accumulated other comprehensive income (loss)
3

 
(8
)
Total stockholders’ equity
6,544

 
6,616

Total liabilities and stockholders’ equity
$
7,685

 
$
7,163


SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED STATEMENT OF CASH FLOWS
For the Years Ended December 31, 2013, 2012 and 2011
(In millions)
2013
 
2012
 
2011
Net cash flows provided by operating activities
$
453

 
$
532

 
$
804

Cash flows from investing activities:
 
 
 
 
 
Money pool advances, net
(371
)
 
24

 
(276
)
Notes receivable – affiliates, net
(23
)
 
(20
)
 
358

Investments in subsidiaries
(50
)
 
(2
)
 
(94
)
Distributions from subsidiaries
1

 
21

 
3

Other
(2
)
 
(5
)
 
(5
)
Net cash flows provided by (used in) investing activities
(445
)
 
18

 
(14
)
Cash flows from financing activities:
 
 
 
 
 
Dividends on common stock
(388
)
 
(382
)
 
(375
)
Short-term debt and credit facility borrowings, net
368

 
(148
)
 
(481
)
Issuances of common stock
—

 
—

 
65

Net cash flows used in financing activities
(20
)
 
(530
)
 
(791
)
Net change in cash and cash equivalents
$
(12
)
 
$
20

 
$
(1
)
Cash and cash equivalents at beginning of year
23

 
3

 
4

Cash and cash equivalents at the end of year
$
11

 
$
23

 
$
3

Cash dividends received from consolidated subsidiaries
$
570

 
$
610

 
$
730

 
 
 
 
 
 
Noncash investing activity – divestiture
$
494

 
$
—

 
$
—

Noncash financing activity – dividends on common stock
—

 
(7
)
 
—

BASIS OF PRESENTATION
Ameren Corporation (parent company only) is a public utility holding company that conducts substantially all of its business operations through its subsidiaries. In accordance with authoritative accounting guidance, Ameren Corporation (parent company only) has accounted for wholly owned subsidiaries using the equity method. These financial statements are presented on a condensed basis. Additional disclosures relating to the parent company financial statements are included within the combined notes under Part II, Item 8, of this report.
SHORT-TERM DEBT AND LIQUIDITY
See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of this report for a description and details of short-term debt and liquidity needs of Ameren Corporation (parent company only).
LONG-TERM OBLIGATIONS
See Note 5 – Long-term Debt and Equity Financings under Part II, Item 8, of this report for a description and details of long-term obligations of Ameren Corporation (parent company only).
COMMITMENTS AND CONTINGENCIES
See Note 15 – Commitments and Contingencies and Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, of this report for a description of all material contingencies and guarantees outstanding of Ameren Corporation (parent company only).
In December 2012, Ameren determined that it intended to, and it was probable that it would, exit its Merchant Generation business before the end of the previously estimated useful lives of that business's long-lived assets. As a result of the 2012 determination, Ameren Corporation (parent company only) recorded a pretax impairment charge of $1.88 billion to reduce its investment in certain of the Merchant Generation segment's coal and natural gas-fired energy centers to their estimated fair values. On December 2, 2013, Ameren completed a divestiture that included a significant portion of that business. As a result of the divestiture in 2013, Ameren Corporation (parent company only) recorded a pretax loss on disposal of $201 million. These charges were included within "Net Income (Loss) Attributable to Ameren Corporation - Discontinued Operations" in the Ameren Corporation (parent company only) Condensed Statement of Income (Loss) and Comprehensive Income (Loss) for the years ended December 31, 2013, and 2012.
The "Miscellaneous accounts and notes receivable" on the December 31, 2013 Ameren Corporation (parent company only) Condensed Balance Sheet included a receivable from Dynegy related to the non-state-regulated subsidiary money pool borrowing balance as of the divestiture date of certain New AER subsidiaries. Additionally, a payable to Dynegy of the estimated working capital adjustment required under the terms of the agreement with IPH is reflected in "Accounts payable" on the December 31, 2013 Ameren Corporation (parent company only) Condensed Balance Sheet. Assuming IPH and Ameren reach an agreement, both the receivable and the payable will be finalized within 120 days after the closing of the divestiture.
See Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, of this report for additional information on the impairment charges recognized in 2013 and 2012 as well as the divestiture.
Schedule II - Valuation And Qualifying Accounts
Valuation And Qualifying Accounts
SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS
FOR THE YEARS ENDED DECEMBER 31, 2013, 2012 AND 2011
(in millions)
 
 
 
 
 
 
 
 
 
Column A
Column B
 
Column C
 
Column D
 
Column E
Description
Balance at
Beginning
of Period
 
(1)
Charged to Costs
and Expenses
 
(2)
Charged to Other
Accounts(a)
 
Deductions(b)
 
Balance at End
of Period
Ameren:
 
 
 
 
 
 
 
 
 
Deducted from assets – allowance for doubtful accounts:
 
 
 
 
 
 
 
 
 
2013
$
17

 
$
35

 
$
4

 
$
38

 
$
18

2012
20

 
30

 
2

 
35

 
17

2011
23

 
41

 
—

 
44

 
20

Deferred tax valuation allowance:
 
 
 
 
 
 
 
 
 
2013
$
2

 
$
5

 
$
—

 
$
—

 
$
7

2012
1

 
1

 
—

 
—

 
2

2011
1

 
—

 
—

 
—

 
1

Ameren Missouri:
 
 
 
 
 
 
 
 
 
Deducted from assets – allowance for doubtful accounts:
 
 
 
 
 
 
 
 
 
2013
$
5

 
$
16

 
$
—

 
$
16

 
$
5

2012
7

 
11

 
—

 
13

 
5

2011
8

 
17

 
—

 
18

 
7

Deferred tax valuation allowance:
 
 
 
 
 
 
 
 
 
2013
$
1

 
$
—

 
$
—

 
$
—

 
$
1

2012
1

 
—

 
—

 
—

 
1

2011
1

 
—

 
—

 
—

 
1

Ameren Illinois:
 
 
 
 
 
 
 
 
 
Deducted from assets – allowance for doubtful accounts:
 
 
 
 
 
 
 
 
 
2013
$
12

 
$
19

 
$
4

 
$
22

 
$
13

2012
13

 
19

 
2

 
22

 
12

2011
13

 
24

 
—

 
24

 
13

Deferred tax valuation allowance:
 
 
 
 
 
 
 
 
 
2013
$
1

 
$
—

 
$
—

 
$
—

 
$
1

2012
—

 
1

 
—

 
—

 
1

2011
—

 
—

 
—

 
—

 
—

(a)
Uncollectible account reserve associated with receivables purchased by Ameren Illinois from alternative retail electric suppliers, as required by the Illinois Public Utilities Act.
(b)
Uncollectible accounts charged off, less recoveries.
Summary Of Significant Accounting Policies (Policy)
General 
Ameren, headquartered in St. Louis, Missouri, is a public utility holding company under PUHCA 2005, administered by FERC. Ameren’s primary assets are its equity interests in its subsidiaries. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of other expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below.
•
Union Electric Company, doing business as Ameren Missouri, operates a rate-regulated electric generation, transmission, and distribution business, and a rate-regulated natural gas transmission and distribution business in Missouri. Ameren Missouri was incorporated in Missouri in 1922 and is successor to a number of companies, the oldest of which was organized in 1881. It is the largest electric utility in the state of Missouri. It supplies electric and natural gas service to a 24,000-square-mile area in central and eastern Missouri. This area has an estimated population of 2.8 million and includes the Greater St. Louis area. Ameren Missouri supplies electric service to 1.2 million customers and natural gas service to 127,000 customers.
•
Ameren Illinois Company, doing business as Ameren Illinois, operates a rate-regulated electric and natural gas transmission and distribution business in Illinois. Ameren Illinois was created by the merger of CILCO and IP with and into CIPS in 2010. CIPS was incorporated in Illinois in 1923 and is the successor to a number of companies, the oldest of which was organized in 1902. Ameren Illinois supplies electric and natural gas utility service to portions of central and southern Illinois having an estimated population of 3.1 million in an area of 40,000 square miles. Ameren Illinois supplies electric service to 1.2 million customers and natural gas service to 767,000 customers.
Ameren has various other subsidiaries responsible for activities such as the provision of shared services. Ameren also has a subsidiary, ATXI, that operates a FERC rate-regulated electric transmission business and is developing the Illinois Rivers project.
Consolidation 
The financial statements of Ameren are prepared on a consolidated basis, and therefore include the accounts of its majority-owned subsidiaries. Ameren Missouri and Ameren Illinois have no subsidiaries and therefore their financial statements are not prepared on a consolidated basis. All significant intercompany transactions have been eliminated. All tabular dollar amounts are in millions, unless otherwise indicated.
Our accounting policies conform to GAAP. Our financial statements reflect all adjustments (which include normal, recurring adjustments) that are necessary, in our opinion, for a fair presentation of our results. The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. Such estimates and assumptions affect reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of financial statements, and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates.
Public Utilities 
Investments
Ameren and Ameren Missouri evaluate for impairment the investments held in Ameren Missouri’s nuclear decommissioning trust fund. Losses on assets in the trust fund could result in higher funding requirements for decommissioning costs, which Ameren Missouri believes would be recovered in electric rates paid by its customers. Accordingly, Ameren and Ameren Missouri recognize a regulatory asset on their balance sheets for losses on investments held in the nuclear decommissioning trust fund.
Purchased Gas, Power and Fuel Rate-adjustment Mechanisms
Ameren Missouri and Ameren Illinois have various rate-adjustment mechanisms in place that provide for the recovery of purchased natural gas and electric fuel and purchased power costs. See Note 2 – Rate and Regulatory Matters for the regulatory assets and liabilities recorded at December 31, 2013, and 2012, related to the rate-adjustment mechanisms discussed below.
In Ameren Missouri’s and Ameren Illinois’ retail natural gas utility jurisdictions, changes in natural gas costs are reflected in billings to their natural gas utility customers through PGA clauses. The differences between actual natural gas costs and costs billed to customers in a given period are deferred as regulatory assets or liabilities. The deferred amounts are either billed or refunded to natural gas utility customers in a subsequent period.
In Ameren Illinois’ retail electric utility jurisdictions, changes in purchased power and transmission service costs are reflected in billings to their electric utility customers through pass-through rate-adjustment clauses. The differences between actual purchased power and transmission service costs and costs billed to customers in a given period are deferred as regulatory assets or liabilities. The deferred amounts are either billed or refunded to electric utility customers in a subsequent period.
Ameren Missouri has a FAC that allows an adjustment of electric rates three times per year for a pass-through to customers of 95% of changes in fuel, certain fuel additives, emission allowances, purchased power costs, transmission costs and revenues, and MISO costs and revenues, net of off-system sales revenues, greater or less than the amount set in base rates without a traditional rate proceeding, subject to MoPSC prudency review. The differences between the cost of fuel incurred and the cost of fuel recovered from Ameren Missouri customers' base rates are deferred as regulatory assets or liabilities. The deferred amounts are either billed or refunded to Ameren Missouri’s electric utility customers in a subsequent period.
Accounting for MISO Transactions
Certain Ameren subsidiaries are regulated by the MoPSC, the ICC, and FERC. In accordance with authoritative accounting guidance regarding accounting for the effects of certain types of regulation, Ameren Missouri and Ameren Illinois defer certain costs as assets pursuant to actions of rate regulators or because of expectations that the companies will be able to recover such costs in rates charged to customers. Ameren Missouri and Ameren Illinois also defer certain amounts as liabilities pursuant to actions of rate regulators or based on the expectation that such amounts will be returned to customers in future rates. Regulatory assets and liabilities are amortized consistent with the period of expected regulatory treatment. In addition to the cost recovery mechanisms discussed in the Purchased Gas, Power and Fuel Rate-adjustment Mechanisms section below, Ameren Missouri and Ameren Illinois have approvals from regulators to use other cost recovery mechanisms. Ameren Missouri has a vegetation management and infrastructure inspection cost tracker, a pension and postretirement benefit cost tracker, an uncertain tax positions tracker, a renewable energy standards cost tracker, a storm restoration cost tracker, and the MEEIA energy efficiency rider. In addition to participating in the IEIMA's formula rate regulatory framework, Ameren Illinois has an environmental cost rider, an asbestos-related litigation rider, an energy efficiency rider, and a bad debt rider. See Note 2 – Rate and Regulatory Matters for additional information on regulatory assets and liabilities. In addition, other costs that Ameren Missouri and Ameren Illinois expect to recover from customers are recorded as construction work in progress and property and plant, net. See Note 3 – Property and Plant, Net.
Environmental Costs
Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are expensed or deferred as a regulatory asset when it is expected that the costs will be recovered from customers in future rates. If environmental expenditures are related to facilities currently in use, such as pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset.
Cash and Cash Equivalents 
Cash and cash equivalents include cash on hand and temporary investments purchased with an original maturity of three months or less.
Allowance for Doubtful Accounts Receivable 
The allowance for doubtful accounts represents our estimate of existing accounts receivable that will ultimately be uncollectible. The allowance is calculated by applying estimated loss factors to various classes of outstanding receivables, including unbilled revenue. The loss factors used to estimate uncollectible accounts are based upon both historical collections experience and management’s estimate of future collections success given the existing and anticipated future collections environment. Ameren Illinois has a rate mechanism that adjusts rates for net write-offs of customer accounts receivable above or below those being collected in rates.
Materials and Supplies 
Materials and supplies are recorded at the lower of cost or market. Cost is determined using the average-cost method. Materials and supplies are capitalized as inventory when purchased and then expensed or capitalized as plant assets when installed, as appropriate.
Property and Plant 
We capitalize the cost of additions to and betterments of units of property and plant. The cost includes labor, material, applicable taxes, and overhead. An allowance for funds used during construction, as discussed below, is also capitalized as a cost of our rate-regulated assets. Maintenance expenditures, including nuclear refueling and maintenance outages, are expensed as incurred. When units of depreciable property are retired, the original costs, less salvage values, are charged to accumulated depreciation. Asset removal costs accrued by our rate-regulated operations that do not constitute legal obligations are classified as a regulatory liability. See Asset Retirement Obligations below and Note 3 – Property and Plant, Net, for additional information.
Depreciation
Depreciation is provided over the estimated lives of the various classes of depreciable property by applying composite rates on a straight-line basis to the cost basis of such property. The provision for depreciation for the Ameren Companies in 2013, 2012 and 2011 ranged from 3% to 4% of the average depreciable cost.
Allowance for Funds Used During Construction 
e capitalize allowance for funds used during construction, or the cost of borrowed funds and the cost of equity funds (preferred and common stockholders’ equity) applicable to rate-regulated construction expenditures, in accordance with the utility industry's accounting practice. Allowance for funds used during construction does not represent a current source of cash funds. This accounting practice offsets the effect on earnings of the cost of financing during construction, and it treats such financing costs in the same manner as construction charges for labor and materials.
Under accepted ratemaking practice, cash recovery of allowance for funds used during construction and other construction costs occurs when completed projects are placed in service and reflected in customer rates.
Goodwill and Intangible Assets 
Goodwill. Goodwill represents the excess of the purchase price of an acquisition over the fair value of the net assets acquired. Ameren and Ameren Illinois had recorded goodwill of $411 million at December 31, 2013, and 2012.
Ameren has two reporting units, which also represent Ameren’s reportable segments. Ameren's reporting units are Ameren Missouri and Ameren Illinois. Ameren Illinois has one reporting unit, Ameren Illinois. Ameren’s and Ameren Illinois' reporting units have been defined and goodwill has been evaluated at the operating segment level in accordance with authoritative accounting guidance. Our reporting units represent businesses for which discrete financial information is available and reviewed regularly by management. All of Ameren's and Ameren Illinois' goodwill at December 31, 2013, and 2012, has been assigned to the Ameren Illinois reporting unit.
We evaluate goodwill for impairment as of October 31 of each year, or more frequently if events and circumstances indicate that the asset might be impaired. Ameren and Ameren Illinois applied a qualitative goodwill evaluation model for their annual goodwill impairment test conducted as of October 31, 2013. Based on the results of Ameren’s and Ameren Illinois’ qualitative assessment, Ameren and Ameren Illinois believe it was more likely than not that the fair value of the Ameren Illinois reporting unit exceeded its carrying value as of October 31, 2013, indicating no impairment of Ameren’s or Ameren Illinois’ goodwill. The following factors, among others, were considered by Ameren and Ameren Illinois when assessing whether it was more likely than not that the fair value of the Ameren Illinois reporting unit exceeded its carrying value for the October 31, 2013, test:
•
macroeconomic conditions, including those conditions within Ameren Illinois’ service territory;
•
pending rate case outcomes and projections of future rate case outcomes;
•
changes in laws and potential law changes;
•
observable industry market multiples;
•
achievement of IEIMA performance metrics and the yield of the 30-year United States treasury bonds; and
•
actual and forecasted financial performance.
The goodwill assigned to the Ameren Illinois reporting unit on the December 31, 2013, balance sheets of Ameren and Ameren Illinois had no accumulated goodwill impairment losses. Ameren and Ameren Illinois will continue to monitor the actual and forecasted operating results, cash flows, market capitalization, and observable industry market multiples of the Ameren Illinois reporting unit for signs of possible declines in estimated fair value and potential goodwill impairment.
Intangible Assets. Ameren and Ameren Missouri classify emission allowances and renewable energy credits as intangible assets. Ameren Illinois consumes renewable energy credits as they are purchased through the IPA procurement process and expenses them immediately. We evaluate intangible assets for impairment if events or changes in circumstances indicate that their carrying amount might be impaired.
At December 31, 2013, Ameren’s and Ameren Missouri’s intangible assets consisted of renewable energy credits obtained through wind and solar power purchase agreements. The book value of Ameren’s and Ameren Missouri’s renewable energy credits was $22 million and $22 million at December 31, 2013, respectively. The book value of Ameren's and Ameren Missouri's renewable energy credits was $14 million and $14 million at December 31, 2012, respectively.
Renewable energy credits and emission allowances are charged to purchased power expense and fuel expense, respectively, as they are used in operations.
Impairment of Long-lived Assets 
We evaluate long-lived assets classified as held and used for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. Whether impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets with the carrying value of the assets. If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount of the carrying value that exceeds the estimated fair value of the assets. In the period in which we determine an asset meets held for sale criteria, we record an impairment charge to the extent the book value exceeds its fair value less cost to sell.
Unamortized Debt Discount, Premium, And Expense 
Discount, premium, and expense associated with long-term debt are amortized over the lives of the related issues.
Revenue 
Operating Revenues
The Ameren Companies record operating revenue for electric or natural gas service when it is delivered to customers. We accrue an estimate of electric and natural gas revenues for service rendered but unbilled at the end of each accounting period.
Beginning in 2012, Ameren Illinois elected to participate in the performance-based formula ratemaking framework pursuant to the IEIMA. The IEIMA provides for an annual reconciliation of Ameren Illinois' electric distribution revenue requirement. As of each balance sheet date, Ameren Illinois records its estimate of the electric distribution revenue impact resulting from the reconciliation of the revenue requirement necessary to reflect the actual costs incurred for that year with the revenue requirement that was in effect for billing purposes for that year. If the current year's revenue requirement is greater than the revenue requirement customer rates were based upon, an increase to electric operating revenues with an offset to a regulatory asset is recorded to reflect the expected recovery of those additional costs from customers within the next two years. If the current year's revenue requirement is less than the revenue requirement customer rates were based upon, a reduction to electric operating revenues with an offset to a regulatory liability is recorded to reflect the expected refund to customers within the next two years. See Note 2 – Rate and Regulatory Matters for information regarding Ameren Illinois' revenue requirement reconciliation pursuant to the IEIMA.
Similar to the IEIMA process described above, Ameren Illinois and ATXI record the impact of a revenue requirement reconciliation for each company's electric transmission jurisdiction, pursuant to FERC-approved rate treatment.
Cost Of Sales 
Accounting for MISO Transactions
Ameren Missouri’s cost of nuclear fuel is capitalized and then amortized to fuel expense on a unit-of-production basis. Spent fuel disposal cost is based on net kilowatthours generated and sold. That cost is charged to "Operating Expenses – Fuel" in the statement of income.
Stock-Based Compensation 
Stock-based compensation cost is measured at the grant date based on the fair value of the award. Ameren recognizes as compensation expense the estimated fair value of stock-based compensation on a straight-line basis over the requisite service period.
Excise Taxes 
Excise taxes levied on us are reflected on Ameren Missouri electric customer bills and on Ameren Missouri and Ameren Illinois natural gas customer bills. They are recorded gross in “Operating Revenues – Electric,” “Operating Revenues – Gas” and “Operating Expenses – Taxes other than income taxes” on the statement of income (loss). Excise taxes reflected on Ameren Illinois electric customer bills are imposed on the customer and are therefore not included in revenues and expenses. They are included in “Taxes accrued” on the balance sheet.
Income Taxes 
Ameren uses an asset and liability approach for its financial accounting and reporting of income taxes, in accordance with authoritative accounting guidance. Deferred tax assets and liabilities are recognized for transactions that are treated differently for financial reporting and income tax return purposes. These deferred tax assets and liabilities are based on statutory tax rates.
We recognize that regulators will probably reduce future revenues for deferred tax liabilities that were initially recorded at rates in excess of the current statutory rate. Therefore, reductions in the deferred tax liability, which were recorded because of decreases in the statutory rate, have been credited to a regulatory liability. A regulatory asset has been established to recognize the probable recovery in rates of future income taxes, resulting from the reversal of the equity portion of the allowance for funds used during construction that was an unrecognized temporary difference prior to the adoption of the authoritative accounting guidance for income taxes.
Investment tax credits used on tax returns for prior years have been deferred in accordance with GAAP. The credits are being amortized over the useful lives of the related investment. Deferred income taxes were recorded on the temporary difference represented by the deferred investment tax credits and a corresponding regulatory liability. This recognizes the expected reduction in rate revenue for future lower income taxes associated with the amortization of the investment tax credits. See Note 13 – Income Taxes.
For certain renewable energy construction projects placed in service, Ameren Missouri elected to seek federal tax grants in lieu of the investment tax credits for which the projects also qualified. These grants were accounted for using a grant recognition accounting model. Ameren Missouri elected to reduce the basis of property as grants were received, which will reduce the amount of depreciation expense recognized in future periods. In 2012, Ameren Missouri received $18 million in federal tax grants.
Ameren Missouri, Ameren Illinois, and all the other Ameren subsidiary companies are parties to a tax allocation agreement with Ameren that provides for the allocation of consolidated tax liabilities. The tax allocation agreement specifies that each party be allocated an amount of tax similar to that which would be owed had the party been separately subject to tax. Any net benefit attributable to the parent is reallocated to other members. That allocation is treated as a contribution of capital to the party receiving the benefit.
Noncontrolling Interest 
Ameren’s noncontrolling interests included the preferred stock not subject to mandatory redemption of Ameren Missouri and Ameren Illinois. As of December 31, 2012, Ameren's noncontrolling interests also included the 20% of EEI not owned by Ameren. All noncontrolling interests are classified as a component of equity separate from Ameren’s equity in its consolidated balance sheet.
Earnings Per Share 
Earnings per Share
Basic earnings per share is computed by dividing net income attributable to Ameren Corporation by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed by dividing net income attributable to Ameren Corporation by the diluted weighted-average number of common shares outstanding during the period. Diluted earnings per share reflects the potential dilution that would occur if certain stock-based performance share units were settled.
Accounting Changes and Other Matters 
Accounting Changes and Other Matters
The following is a summary of recently adopted authoritative accounting guidance, as well as guidance issued but not yet adopted, that could affect the Ameren Companies.
Presentation of Comprehensive Income
In June 2011, FASB amended its guidance on the presentation of comprehensive income in financial statements. The amended guidance changed the presentation of comprehensive income in the financial statements. It requires entities to report components of comprehensive income either in a continuous statement of comprehensive income or in two separate but consecutive statements. This guidance was effective for the Ameren Companies beginning in the first quarter of 2012 with retroactive application required. The implementation of the amended guidance did not affect the Ameren Companies’ results of operations, financial position, or liquidity.
In February 2013, FASB amended this guidance to require an entity to provide information about the amounts reclassified out of accumulated OCI by component. In addition, an entity is required to present significant amounts reclassified out of accumulated OCI by the respective line items of net income either on the face of the statement where net income is presented or in the footnotes. This guidance was effective for the Ameren Companies beginning in the first quarter of 2013. The implementation of this amended guidance did not affect the Ameren Companies’ results of operations, financial position, or liquidity. The amounts reclassified out of accumulated OCI for the Ameren Companies corresponding to continuing operations related to pension and other postretirement plan activity. These amounts were immaterial for the year ended December 31, 2013, and therefore no additional disclosures were required.
Disclosures about Offsetting Assets and Liabilities
In December 2011, FASB issued additional authoritative accounting guidance to improve information disclosed about financial and derivative instruments. The guidance requires an entity to disclose information about offsetting and related arrangements to enable users of the financial statements to understand the effect of those arrangements on its financial position. In January 2013, FASB amended this guidance to limit the scope to derivative instruments, repurchase agreements and reverse repurchase agreements, and securities borrowing and securities lending transactions. The Ameren Companies adopted this guidance for the first quarter of 2013. The implementation of this additional guidance did not affect the Ameren Companies’ results of operations, financial positions, or liquidity, as this guidance only requires additional disclosures. See Note 7 – Derivative Financial Instruments for the required additional disclosures.
Presentation of an Unrecognized Tax Benefit
In July 2013, FASB issued additional authoritative accounting guidance to provide clarity for the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. It requires entities to present an unrecognized tax benefit as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward to the extent a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is available under the tax law. Currently, any unrecognized tax benefit is recorded in “Other deferred credits and liabilities” on Ameren's, Ameren Missouri's, and Ameren Illinois' balance sheets. After this guidance becomes effective, any unrecognized tax benefit will be recorded in “Accumulated deferred income taxes, net” as a reduction to the deferred tax assets for net operating loss, a similar tax loss, and tax credit carryforwards on the respective balance sheets. At December 31, 2013, unrecognized tax benefits of $48 million and $15 million would have been recorded in “Accumulated deferred income taxes, net” at Ameren and Ameren Missouri, respectively under this new guidance. To the extent that an unrecognized tax benefit exceeds these carryforwards, the excess would continue to be recorded in “Other deferred credits and liabilities” on the respective balance sheets, consistent with current authoritative accounting guidance. The amended guidance will not affect the Ameren Companies' results of operations or liquidity, as this guidance is presentation-related only. This guidance will be effective for the Ameren Companies beginning in the first quarter of 2014.
Asset Retirement Obligations 
Authoritative accounting guidance requires us to record the estimated fair value of legal obligations associated with the retirement of tangible long-lived assets in the period in which the liabilities are incurred and to capitalize a corresponding amount as part of the book value of the related long-lived asset. In subsequent periods, we are required to make adjustments to AROs based on changes in the estimated fair values of the obligations. Corresponding increases in asset book values are depreciated over the remaining useful life of the related asset. Uncertainties as to the probability, timing, or amount of cash flows associated with AROs affect our estimates of fair value. Ameren and Ameren Missouri have recorded AROs for retirement costs associated with Ameren Missouri’s Callaway energy center decommissioning costs, asbestos removal, CCR storage facilities, and river structures. Also, Ameren and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal. In addition, Ameren, Ameren Missouri and Ameren Illinois have recorded AROs for the disposal of certain transformers.
Asset removal costs accrued by our rate-regulated operations that do not constitute legal obligations are classified as a regulatory liability.
Summary Of Significant Accounting Policies (Tables)
Schedule Of Materials And Supplies 
The following table presents a breakdown of materials and supplies for each of the Ameren Companies at December 31, 2013, and 2012:
 
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2013
 
 
 
 
 
 
Fuel(a)
 
$
144

 
$
—

 
$
144

Gas stored underground
 
17

 
110

 
127

Other materials and supplies
 
191

 
64

 
255

 
 
$
352

 
$
174

 
$
526

2012
 
 
 
 
 
 
Fuel(a)
 
$
198

 
$
—

 
$
198

Gas stored underground
 
18

 
113

 
131

Other materials and supplies
 
181

 
60

 
241

 
 
$
397

 
$
173

 
$
570

(a)
Consists of coal, oil, and propane.

Schedule Of Rates Used For Allowance For Funds Used During Construction 
The following table presents the annual allowance for funds used during construction rates that were utilized during 2013, 2012 and 2011:
 
2013
 
2012
 
2011
Ameren Missouri
8
%
 
8
%
 
8
%
Ameren Illinois
8
%
 
9
%
 
9
%
Schedule Of Amortization Based On Usage Of Renewable Energy Credits And Emission Allowances 
 
 
2013
 
2012
 
2011
Ameren Missouri
$
(a)

$
(a)

$
(a)

Ameren Illinois
 
13

 
4

 
3

Ameren
$
13

$
4

$
3

(a)
Less than $1 million.
Schedule Of Excise Taxes 
The following table presents excise taxes recorded in “Operating Revenues – Electric,” “Operating Revenues – Gas,” and “Operating Expenses – Taxes other than income taxes” for the years ended 2013, 2012 and 2011:
 
2013
 
2012
 
2011
Ameren Missouri
$
152

 
$
139

 
$
137

Ameren Illinois
61

 
54

 
57

Ameren
$
213

 
$
193

 
$
194

Schedule of Earnings Per Share, Basic and Diluted 
The following table presents Ameren’s basic and diluted earnings per share calculations and reconciles the weighted-average number of common shares outstanding to the diluted weighted-average number of common shares outstanding for the years ended December 31, 2013, 2012 and 2011:
 
2013
 
2012
 
2011
Net income (loss) attributable to Ameren Corporation:
 
 
 
 
 
Continuing operations
$
512

 
$
516

 
$
431

Discontinued operations
(223
)
 
(1,490
)
 
88

Net income (loss) attributable to Ameren Corporation
$
289

 
$
(974
)
 
$
519

 
 
 
 
 
 
Average common shares outstanding – basic
242.6

 
242.6

 
241.5

Assumed settlement of performance share units
1.9

 
0.4

 
0.6

Average common shares outstanding – diluted
244.5

 
243.0

 
242.1

 
 
 
 
 
 
Earnings (loss) per common share – basic:
 
 
 
 
 
Continuing operations
$
2.11

 
$
2.13

 
$
1.79

Discontinued operations
(0.92
)
 
(6.14
)
 
0.36

Earnings (loss) per common share – basic
$
1.19

 
$
(4.01
)
 
$
2.15

 
 
 
 
 
 
Earnings (loss) per common share – diluted:
 
 
 
 
 
Continuing operations
$
2.10

 
$
2.13

 
$
1.79

Discontinued operations
(0.92
)
 
(6.14
)
 
0.36

Earnings (loss) per common share – diluted
$
1.18

 
$
(4.01
)
 
$
2.15

 
 
 
 
 
 
Average performance share units excluded from calculation(a)
0.1

 
0.7

 
—

(a)
Weighted-average number of performance share units that were excluded from the “Assumed settlement of performance share units” provided above because the performance or market conditions related to the awards had not yet been met.
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] 
The following table presents additional information regarding Ameren's consolidated statement of cash flows for the years ended December 31, 2013, 2012 and 2011:
 
2013
 
2012
 
2011
Cash paid (refunded) during the year:

 
 
 
 
 
Interest
 
 
 
 
 
Continuing operations(a)
$
362

 
$
384

 
$
393

Discontinued operations(b)
31

 
49

 
60

 
$
393

 
$
433

 
$
453

 
 
 
 
 
 
Income taxes, net
 
 
 
 
 
Continuing Operations
$
116

 
$
10

 
$
(47
)
Discontinued Operations
(108
)
 
(9
)
 
(14
)
 
$
8

 
$
1

 
$
(61
)
(a)
Net of $20 million, $17 million, and $27 million capitalized, respectively.
(b)
Net of $17 million, $13 million, and $3 million capitalized, respectively.
Schedule Of Asset Retirement Obligations 
The following table provides a reconciliation of the beginning and ending carrying amount of AROs for the years ended December 31, 2013, and 2012:
 
Ameren
Missouri(a)
 
Ameren
Illinois(b)
 
Ameren(a)
 
Balance at December 31, 2011
$
328

 
$
3

 
$
331

 
Liabilities incurred
—

 
—

 
—

 
Liabilities settled
(1
)
 
(c)

 
(1
)
 
Accretion in 2012(d)
18

 
(c)

 
18

 
Change in estimates(e)
1

 
(c)

 
1

 
Balance at December 31, 2012
$
346

 
$
3

 
$
349

 
Liabilities incurred
—

 
—

 
—

 
Liabilities settled
(1
)
 
(c)

 
(1
)
 
Accretion in 2013(d)
19

 
(c)

 
19

 
Change in estimates(e)
2

 
(c)

 
2

 
Balance at December 31, 2013
$
366

 
$
3

 
$
369

 
(a)
The nuclear decommissioning trust fund assets of $494 million and $408 million as of December 31, 2013, and 2012, respectively, are restricted for decommissioning of the Callaway energy center.
(b)
Balance included in “Other deferred credits and liabilities” on the balance sheet.
(c)
Less than $1 million.
(d)
Accretion expense was recorded as an increase to regulatory assets at Ameren Missouri and Ameren Illinois.
(e)
Ameren Missouri changed its fair value estimates for asbestos removal in 2012 and 2013, and for certain CCR storage facilities in 2013.                    
See Note 16 – Divestiture Transactions and Discontinued Operations for additional information on the AROs related to the abandoned Meredosia and Hutsonville energy centers, which are presented as discontinued operations and therefore not included in the table above.

Rate And Regulatory Matters (Tables)
Schedule Of Regulatory Assets And Liabilities
The following table presents Ameren’s, Ameren Missouri’s and Ameren Illinois’ regulatory assets and regulatory liabilities at December 31, 2013, and 2012:
 
 
2013
 
2012
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Current regulatory assets:
 
 
 
 
 
 
 
 
 
 
 
 
 
Under-recovered FAC(a)(b)
 
$
104

 
$
—

 
$
104

 
 
$
145

 
$
—

 
$
145

Under-recovered Illinois electric power costs(c)
 
—

 
1

 
1

 
 
—

 
—

 
—

Under-recovered PGA(c)
 
—

 
1

 
1

 
 
5

 
7

 
12

MTM derivative losses(d)
 
14


36

 
50

 
 
13

 
77

 
90

Total current regulatory assets
 
$
118

 
$
38

 
$
156

 
 
$
163

 
$
84

 
$
247

Noncurrent regulatory assets:
 
 
 
 
 
 
 
 
 
 
 
 
 
Pension and postretirement benefit costs(e)
 
$
44

 
$
140

 
$
184

 
 
$
348

 
$
424

 
$
772

Income taxes(f)
 
230

 
7

 
237

 
 
231

 
4

 
235

Asset retirement obligations(g)
 
—

 
5

 
5

 
 
—

 
5

 
5

Callaway costs(a)(h)
 
40

 
—

 
40

 
 
44

 
—

 
44

Unamortized loss on reacquired debt(a)(i)
 
77

 
74

 
151

 
 
81

 
100

 
181

Recoverable costs – contaminated facilities(j)
 
—

 
271

 
271

 
 
—

 
248

 
248

MTM derivative losses(d)
 
8


118

 
126



7

 
128

 
135

Storm costs(k)
 
5

 
3

 
8

 
 
9

 
—

 
9

Demand-side costs before MEEIA implementation(a)(l)
 
58

 
—

 
58

 
 
73

 
—

 
73

Reserve for workers’ compensation liabilities(m)
 
6

 
6

 
12

 
 
6

 
6

 
12

Credit facilities fees(n)
 
5

 
—

 
5

 
 
6

 
—

 
6

Common stock issuance costs(o)
 
4

 
—

 
4

 
 
7

 
—

 
7

Construction accounting for pollution control equipment(a)(p)
 
22

 
—

 
22

 
 
23

 
—

 
23

Solar rebate program(a)(q)
 
27

 
—

 
27

 
 
5

 
—

 
5

IEIMA revenue requirement reconciliation(r)
 
—

 
65

 
65

 
 
—

 
—

 
—

Other(s)(t)
 
8

 
12

 
25

 
 
12

 
19

 
31

Total noncurrent regulatory assets
 
$
534

 
$
701

 
$
1,240

 
 
$
852

 
$
934

 
$
1,786

Current regulatory liabilities:
 
 
 
 
 
 
 
 
 
 
 
 
 
Over-recovered FAC(b)
 
$
26

 
$
—

 
$
26

 
 
$
—

 
$
—

 
$
—

Over-recovered Illinois electric power costs(c)
 
—

 
51

 
51

 
 
—

 
58

 
58

Over-recovered PGA(c)
 
5

 
29

 
34

 
 
—

 
15

 
15

MTM derivative gains(d)
 
26

 
1

 
27


 
18

 
1

 
19

Wholesale distribution refund(u)
 
—

 
13

 
13

 
 
—

 
8

 
8

IEIMA revenue requirement reconciliation(r)
 
—

 
65

 
65

 
 
—

 
—

 
—

Total current regulatory liabilities
 
$
57

 
$
159

 
$
216

 
 
$
18

 
$
82

 
$
100

Noncurrent regulatory liabilities:
 
 
 
 
 
 
 
 
 
 
 
 
 
Income taxes(v)
 
$
38

 
$
3

 
$
41

 
 
$
42

 
$
4

 
$
46

Removal costs(w)
 
828

 
610

 
1,438

 
 
766

 
581

 
1,347

Asset retirement obligation(g)
 
146

 
—

 
146

 
 
80

 
—

 
80

MTM derivative gains(d)
 
1

 
—

 
1


 
2

 
—

 
2

Bad debt riders(x)
 
—

 
8

 
8

 
 
—

 
12

 
12

Pension and postretirement benefit costs tracker(y)
 
15

 
—

 
15

 
 
23

 
—

 
23

Energy efficiency riders(z)
 
3

 
33

 
36

 
 
—

 
20

 
20

IEIMA revenue requirement reconciliation(r)
 
—

 
—

 
—

 
 
—

 
55

 
55

FERC transmission revenue requirement reconciliation(aa)
 
—

 
10

 
10

 
 
—

 
—

 
—

Other(ab)
 
10

 
—

 
10

 
 
4

 
—

 
4

Total noncurrent regulatory liabilities
 
$
1,041

 
$
664

 
$
1,705

 
 
$
917

 
$
672

 
$
1,589

(a)
These assets earn a return.
(b)
Under-recovered or over-recovered fuel costs to be recovered through the FAC. Specific accumulation periods aggregate the under-recovered or over-recovered costs over four months, any related adjustments that occur over the following four months, and the recovery from customers that occurs over the next eight months.
(c)
Costs under- or over-recovered from utility customers. Amounts will be recovered from, or refunded to, customers within one year of the deferral.
(d)
Deferral of commodity-related derivative MTM losses or gains. See Note 7 – Derivative Financial Instruments for additional information.
(e)
These costs are being amortized in proportion to the recognition of prior service costs (credits), transition obligations (assets), and actuarial losses (gains) attributable to Ameren’s pension plan and postretirement benefit plans. See Note 11 – Retirement Benefits for additional information.
(f)
Offset to certain deferred tax liabilities for expected recovery of future income taxes when paid. This will be recovered over the expected life of the related assets.
(g)
Recoverable or refundable removal costs for AROs, including net realized and unrealized gains and losses related to the nuclear decommissioning trust fund investments. See Note 1 – Summary of Significant Accounting Policies – Asset Retirement Obligations.
(h)
Ameren Missouri’s Callaway energy center operations and maintenance expenses, property taxes, and carrying costs incurred between the plant in-service date and the date the plant was reflected in rates. These costs are being amortized over the remaining life of the energy center's current operating license, which expires in 2024.
(i)
Losses related to reacquired debt. These amounts are being amortized over the lives of the related new debt issuances or the original lives of the old debt issuances if no new debt was issued.
(j)
The recoverable portion of accrued environmental site liabilities that will be collected from electric and natural gas customers through ICC-approved cost recovery riders. The period of recovery will depend on the timing of remediation expenditures. See Note 15 – Commitments and Contingencies for additional information.
(k)
Actual storm costs in a test year that exceed the MoPSC staff’s normalized storm costs for rate purposes. As approved by the December 2012 MoPSC electric rate order, the 2006, 2007, and 2008 storm costs are being amortized through December 2014. As approved by the May 2010 MoPSC electric rate order, the 2009 storm costs are being amortized through June 2015. The Ameren Illinois total includes 2013 storm costs deferred in accordance with the IEIMA. These costs are being amortized over a five-year period beginning in 2013.
(l)
Demand-side costs incurred prior to implementation of the MEEIA in 2013, including the costs of developing, implementing and evaluating customer energy efficiency and demand response programs. Costs incurred from May 2008 through September 2008 are being amortized over a 10-year period that began in March 2009. Costs incurred from October 2008 through December 2009 are being amortized over a six-year period that began in July 2010. Costs incurred from January 2010 through February 2011 are being amortized over a six-year period that began in August 2011. Costs incurred from March 2011 through July 2012 are being amortized over a six-year period that began in January 2013.
(m)
Reserve for workers’ compensation claims. The period of recovery will depend on the timing of actual expenditures.
(n)
Ameren Missouri’s costs incurred to enter into and maintain the 2012 Ameren Missouri Credit Agreement. These costs are being amortized over five years, beginning in November 2012. These costs are being amortized to construction work in progress, which will be depreciated when assets are placed into service.
(o)
The MoPSC’s May 2010 electric rate order allowed Ameren Missouri to recover its portion of Ameren’s September 2009 common stock issuance costs. These costs are being amortized over five years, beginning in July 2010.
(p)
The MoPSC’s May 2010 electric rate order allowed Ameren Missouri to record an allowance for funds used during construction for pollution control equipment at its Sioux energy center until the cost of that equipment could be included in customer rates. These costs will be amortized over the expected life of the Sioux energy center, which is currently through 2033.
(q)
Costs associated with Ameren Missouri's solar rebate program beginning in August 2012 to fulfill Ameren Missouri's renewable energy portfolio requirement. The amortization period for these costs will be three years, commencing with the next Ameren Missouri electric rate case order.
(r)
The asset balance relates to the difference between Ameren Illinois' 2013 revenue requirement calculated under the IEIMA's performance-based formula ratemaking framework, and the revenue requirement included in customer rates for 2013. Subject to ICC approval, this asset will be collected from customers in 2015. The liability balance relates to the difference between Ameren Illinois' 2012 revenue requirement calculated under the IEIMA's performance-based formula ratemaking framework and the revenue requirement included in customer rates for 2012. This liability will be refunded to customers in 2014.
(s)
The Ameren Illinois total includes Ameren Illinois Merger integration and optimization costs, which are amortized over four years, beginning in January 2012. The Ameren Illinois total also includes costs related to the 2013 natural gas delivery service rate case costs, which are being amortized over a two-year period that began in January 2014. The Ameren Illinois total also includes a portion of the unamortized debt fair value adjustment recorded upon Ameren's acquisition of IP. This portion is being amortized over the remaining life of the related debt. At Ameren Missouri, the balance primarily includes the cost of renewable energy credits to fulfill its renewable energy portfolio requirement. Costs incurred from January 2010 through July 2012 are being amortized over three years, beginning in January 2013.
(t)
The Ameren total includes $5 million for ATXI's revenue requirement reconciliation adjustments for 2012 and 2013 calculated pursuant to the FERC's electric transmission formula ratemaking framework. These adjustments will be collected from customers in 2014 for the 2012 revenue requirement reconciliation and in 2015 for the 2013 revenue requirement reconciliation.
(u)
Estimated refund to wholesale electric customers. See 2011 Wholesale Distribution Rate Case above.
(v)
Unamortized portion of investment tax credits, federal excess deferred taxes, and uncertain tax position tracker. The tracker is being amortized over three years, beginning in January 2013. The unamortized portion of investment tax credit is being amortized over the expected life of the underlying assets.
(w)
Estimated funds collected for the eventual dismantling and removal of plant from service, net of salvage value, upon retirement related to our rate-regulated operations.
(x)
A regulatory tracking mechanism for the difference between the level of bad debt expense incurred by Ameren Illinois under GAAP and the level of such costs included in electric and natural gas rates. The over-recovery relating to 2011 was refunded to customers from June 2012 through May 2013. The over-recovery relating to 2012 is being refunded to customers from June 2013 through May 2014. The over-recovery relating to 2013 will be refunded to customers from June 2013 through May 2014.
(y)
A regulatory tracking mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri under GAAP and the level of such costs built into rates. For periods prior to August 2012, the MoPSC's December 2012 electric rate order directed the amortization to occur over five years, beginning in January 2013. For periods after August 2012, the amortization period will be determined in a future Ameren Missouri electric rate case.
(z)
The Ameren Illinois balance relates its regulatory tracking mechanism to recover its electric and natural gas costs associated with developing, implementing, and evaluating customer energy efficiency and demand response programs. This over-recovery will be refunded to customers over the following 12 months after the plan year. The Ameren Missouri balance relates to its MEEIA program costs incurred and projected lost revenues compared to the amount previously collected from customers. Beginning in January 2014, a MEEIA rider allows Ameren Missouri to collect from or refund to customers any annual difference in the actual amounts incurred and the projected amounts collected from customers for the MEEIA program costs and its projected lost revenues. Under the MEEIA rider, collections from or refunds to customers occur one year after the program costs and projected lost revenues are incurred.
(aa)
Ameren Illinois' 2013 revenue requirement reconciliation adjustment calculated pursuant to the FERC's electric transmission formula ratemaking framework. This liability will be refunded to customers in 2015.
(ab)
Balance primarily includes the costs of renewable energy credits to fulfill Ameren Missouri's renewable energy portfolio requirement from August 2012 through December 2013, which were less than the amount included in rates. The amortization period for this over-recovery will be determined in a future Ameren Missouri electric rate case.
Property And Plant, Net (Tables)
Schedule Of Property And Plant, Net 
The following table presents property and plant, net, for each of the Ameren Companies at December 31, 2013, and 2012:
 
 
Ameren
Missouri(a)
 
Ameren
Illinois
 
Other
 
Ameren(a)(b)
2013
 
 
 
 
 
 
 
 
Property and plant, at original cost:
 
 
 
 
 
 
 
 
Electric
 
$
15,964

 
$
5,426

 
$
336

 
$
21,726

Natural gas
 
413

 
1,562

 
—

 
1,975

 
 
16,377

 
6,988

 
336

 
23,701

Less: Accumulated depreciation and amortization
 
6,766

 
1,627

 
251

 
8,644

 
 
9,611

 
5,361

 
85

 
15,057

Construction work in progress:
 
 
 
 
 
 
 
 
Nuclear fuel in process
 
246

 
—

 
—

 
246

Other
 
595

 
228

 
79

 
902

Property and plant, net
 
$
10,452

 
$
5,589

 
$
164

 
$
16,205

2012
 
 
 
 
 
 
 
 
Property and plant, at original cost:
 
 
 
 
 
 
 
 
Electric
 
$
15,638

 
$
4,985

 
$
319

 
$
20,942

Natural gas
 
393

 
1,461

 
—

 
1,854

 
 
16,031

 
6,446

 
319

 
22,796

Less: Accumulated depreciation and amortization
 
6,614

 
1,495

 
237

 
8,346

 
 
9,417

 
4,951

 
82

 
14,450

Construction work in progress:
 
 
 
 
 
 
 
 
Nuclear fuel in process
 
317

 
—

 
—

 
317

Other
 
427

 
101

 
53

 
581

Property and plant, net
 
$
10,161

 
$
5,052

 
$
135

 
$
15,348



(a)
Amounts in Ameren and Ameren Missouri include two electric generation CTs under separate capital lease agreements. The gross cumulative asset value of those agreements was $228 million at December 31, 2013, and $228 million at December 31, 2012. The total accumulated depreciation associated with the two CTs was $56 million and $52 million at December 31, 2013, and 2012, respectively. In addition, Ameren Missouri has investments in debt securities, which were classified as held-to-maturity, related to the two CTs from the city of Bowling Green and Audrain County. As of December 31, 2013, and 2012, the carrying value of these debt securities was $299 million and $304 million, respectively.
(b)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Accrued Capital Expenditures 
The following table provides accrued capital and nuclear fuel expenditures at December 31, 2013, 2012, and 2011, which represent noncash investing activity excluded from the accompanying statements of cash flows:
 
Ameren(a)
 
Ameren
Missouri
 
Ameren
Illinois
Accrued capital expenditures:
 
 
 
 
 
2013
$
175

 
$
74

 
$
86

2012
107

 
63

 
37

2011
97

 
73

 
18

Accrued nuclear fuel expenditures:
 
 
 
 
 
2013
8

 
8

 
(b)

2012
8

 
8

 
(b)

2011
36

 
36

 
(b)


(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Short-Term Debt And Liquidity (Tables)
Schedule Of Maximum Aggregate Amount Available On Credit Agreements 
The maximum aggregate amount available to each borrower under each facility is shown in the following table (such amount being such borrower's "Borrowing Sublimit"):
 
 
2012 Missouri Credit Agreement
2012 Illinois
Credit Agreement
Ameren
$
500

$
300

Ameren Missouri
 
800

(a)

Ameren Illinois
 
(a)

800

(a)
Not applicable.
Schedule of Commercial Paper 
mercial Paper
The following table summarizes the borrowing activity and relevant interest rates under Ameren's commercial paper program, for the years ended December 31, 2013, and 2012:
 
 
2013
 
2012
Average daily borrowings outstanding
 
$
54

 
$
49

Outstanding borrowings at period-end
 
368

 
—

Weighted-average interest rate
 
0.56
%
 
0.92
%
Peak borrowings during period
 
$
368

 
$
229

Peak interest rate
 
0.85
%
 
1.25
%
Long-Term Debt And Equity Financings (Tables)
Schedule of Long-term Debt Instruments 
The following table presents long-term debt outstanding, including maturities due within one year, for the Ameren Companies as of December 31, 2013, and 2012:
 
2013
 
2012
Ameren (Parent):
 
 
 
8.875% Senior unsecured notes due 2014
$
425

 
$
425

Less: Unamortized discount and premium
—

 
(1
)
Less: Maturities due within one year
(425
)
 
—

Long-term debt, net
$
—

 
$
424

Ameren Missouri:
 
 
 
Senior secured notes:(a)
 
 
 
4.65% Senior secured notes due 2013
—

 
200

5.50% Senior secured notes due 2014
104

 
104

4.75% Senior secured notes due 2015
114

 
114

5.40% Senior secured notes due 2016
260

 
260

6.40% Senior secured notes due 2017
425

 
425

6.00% Senior secured notes due 2018(b)
179

 
179

5.10% Senior secured notes due 2018
199

 
199

6.70% Senior secured notes due 2019(b)
329

 
329

5.10% Senior secured notes due 2019
244

 
244

5.00% Senior secured notes due 2020
85

 
85

5.50% Senior secured notes due 2034
184

 
184

5.30% Senior secured notes due 2037
300

 
300

8.45% Senior secured notes due 2039(b)
350

 
350

3.90% Senior secured notes due 2042(b)
485

 
485

Environmental improvement and pollution control revenue bonds:
 
 
 
1992 Series due 2022(c)(d)
47

 
47

1993 5.45% Series due 2028(e)
(e)

 
44

1998 Series A due 2033(c)(d)
60

 
60

1998 Series B due 2033(c)(d)
50

 
50

1998 Series C due 2033(c)(d)
50

 
50

Capital lease obligations:
 
 
 
City of Bowling Green capital lease (Peno Creek CT) through 2022
59

 
64

Audrain County capital lease (Audrain County CT) due 2023
240

 
240

Total long-term debt, gross
3,764

 
4,013

Less: Unamortized discount and premium
(7
)
 
(7
)
Less: Maturities due within one year
(109
)
 
(205
)
Long-term debt, net
$
3,648

 
$
3,801

 
2013
 
2012
Ameren Illinois:
 
 
 
Senior secured notes:
 
 
 
8.875% Senior secured notes due 2013(f)
$
—

 
$
150

6.20% Senior secured notes due 2016(f)
54

 
54

6.25% Senior secured notes due 2016(g)
75

 
75

6.125% Senior secured notes due 2017(g)(h)
250

 
250

6.25% Senior secured notes due 2018(g)(h)
144

 
144

9.75% Senior secured notes due 2018(g)(h)
313

 
313

2.70% Senior secured notes due 2022(g)(h)
400

 
400

6.125% Senior secured notes due 2028(g)
60

 
60

6.70% Senior secured notes due 2036(g)
61

 
61

6.70% Senior secured notes due 2036(f)
42

 
42

4.80% Senior secured notes due 2043(g)
280

 
—

Environmental improvement and pollution control revenue bonds:
 
 
 
5.90% Series 1993 due 2023(i)
32

 
32

5.70% 1994A Series due 2024(j)
36

 
36

1993 Series C-1 5.95% due 2026(k)
35

 
35

1993 Series C-2 5.70% due 2026(k)
8

 
8

1993 Series B-1 due 2028(d)(k)
17

 
17

5.40% 1998A Series due 2028(j)
19

 
19

5.40% 1998B Series due 2028(j)
33

 
33

Fair-market value adjustments
4

 
4

Total long-term debt, gross
1,863

 
1,733

Less: Unamortized discount and premium
(7
)
 
(6
)
Less: Maturities due within one year
—

 
(150
)
Long-term debt, net
$
1,856

 
$
1,577

Ameren consolidated long-term debt, net
$
5,504

 
$
5,802

(a)
These notes are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Missouri mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Missouri first mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the first mortgage bond lien protection associated with these notes to fall away until 2042.
(b)
Ameren Missouri has agreed, during the life of these notes, not to optionally redeem, purchase or otherwise retire in full its first mortgage bonds. Ameren Missouri has also agreed to prevent a first mortgage bond release date from occurring as long as any of the 8.45% senior secured notes due 2039 and any of the 3.90% senior secured notes due 2042 remain outstanding.
(c)
These bonds are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture and have a fall-away lien provision similar to that of Ameren Missouri's senior secured notes. The bonds are also backed by an insurance guarantee policy.
(d)
Interest rates, and periods during which such rates apply, vary depending on our selection of defined rate modes. Maximum interest rates could range up to 18% depending on the series of bonds. The average interest rates for 2013 and 2012 were as follows:
 
2013
 
2012
Ameren Missouri 1992 Series
0.17%
 
0.30%
Ameren Missouri 1998 Series A
0.34%
 
0.65%
Ameren Missouri 1998 Series B
0.33%
 
0.64%
Ameren Missouri 1998 Series C
0.34%
 
0.64%
Ameren Illinois 1993 Series B-1
0.14%
 
0.22%

(e)
These bonds are first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage bond indenture and are secured by substantially all Ameren Missouri property and franchises. The bonds are callable at 100% of par value. Less than $1 million principal amount of the bonds remain outstanding.
(f)
These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under the CILCO mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the CILCO mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the CILCO first mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the first mortgage bond lien protection associated with these notes to fall away until 2023.
(g)
These notes are collaterally secured by mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the Ameren Illinois mortgage indenture remain outstanding. Redemption, purchase, or maturity of all mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Illinois mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the mortgage bond lien protection associated with these notes to fall away until 2028.
(h)
Ameren Illinois has agreed, during the life of these notes, not to optionally redeem, purchase, or otherwise retire in full its Ameren Illinois mortgage bonds; therefore, an Ameren Illinois first mortgage bond release date will not occur as long as any of these notes are outstanding.
(i)
These bonds are first mortgage bonds issued by Ameren Illinois under the CILCO mortgage indenture and are secured by substantially all property of the former CILCO. The bonds are callable at 100% of par value.
(j)
These bonds are mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture and are secured by substantially all property of the former IP and CIPS. The bonds are callable at 100% of par value. The bonds are also backed by an insurance guarantee policy.
(k)
The bonds are callable at 100% of par value.
Schedule Of Maturities Of Long-Term Debt 
The following table presents the aggregate maturities of long-term debt, including current maturities, for the Ameren Companies at December 31, 2013:
 
 Ameren
(Parent)(a)
 
 Ameren
Missouri(a)
 
 Ameren
Illinois(a)(b)
 
Ameren
Consolidated
2014
$
425

 
$
109

 
$
—

 
$
534

2015
—

 
120

 
—

 
120

2016
—

 
266

 
129

 
395

2017
—

 
431

 
250

 
681

2018
—

 
383

 
457

 
840

Thereafter
—

 
2,455

 
1,023

 
3,478

Total
$
425

 
$
3,764

 
$
1,859

 
$
6,048

(a)
Excludes unamortized discount and premium of $7 million and $7 million at Ameren Missouri and Ameren Illinois, respectively.
(b)
Excludes $4 million related to Ameren Illinois’ long-term debt fair-market value adjustments, which are being amortized to interest expense over the remaining life of the debt.
Schedule Of Outstanding Preferred Stock 
 
 
 
Redemption Price(per share)
 
2013
 
2012
Ameren Missouri:
 
 
 
 
 
 
 
Without par value and stated value of $100 per share, 25 million shares authorized
 
 
 
 
 
 
$3.50 Series
130,000 shares
 
$
110.00

 
$
13

 
$
13

$3.70 Series
40,000 shares
 
104.75

 
4

 
4

$4.00 Series
150,000 shares
 
105.625

 
15

 
15

$4.30 Series
40,000 shares
 
105.00

 
4

 
4

$4.50 Series
213,595 shares
 
110.00

(a) 
21

 
21

$4.56 Series
200,000 shares
 
102.47

 
20

 
20

$4.75 Series
20,000 shares
 
102.176

 
2

 
2

$5.50 Series A
14,000 shares
 
110.00

 
1

 
1

Total
 
 
 
$
80

 
$
80

Ameren Illinois:
 
 
 
 
 
 
 
With par value of $100 per share, 2 million shares authorized
 
 
 
 
 
 
4.00% Series
144,275 shares
 
$
101.00

 
$
14

 
$
14

4.08% Series
45,224 shares
 
103.00

 
5

 
5

4.20% Series
23,655 shares
 
104.00

 
2

 
2

4.25% Series
50,000 shares
 
102.00

 
5

 
5

4.26% Series
16,621 shares
 
103.00

 
2

 
2

4.42% Series
16,190 shares
 
103.00

 
2

 
2

4.70% Series
18,429 shares
 
103.00

 
2

 
2

4.90% Series
73,825 shares
 
102.00

 
7

 
7

4.92% Series
49,289 shares
 
103.50

 
5

 
5

5.16% Series
50,000 shares
 
102.00

 
5

 
5

6.625% Series
124,274 shares
 
100.00

 
12

 
12

7.75% Series
4,542 shares
 
100.00

 
1

 
1

Total
 
 
 
$
62

 
$
62

Total Ameren
 
 
 
$
142

 
$
142

(a)
In the event of voluntary liquidation, $105.50.
Schedule of Required and Actual Debt Ratios 
The following table summarizes the required and actual interest coverage ratios for interest charges and dividend coverage ratios and bonds and preferred stock issuable as of December 31, 2013, at an assumed interest rate of 6% and dividend rate of 7%.
 
Required Interest
Coverage Ratio(a)
Actual Interest
Coverage Ratio
Bonds Issuable(b)
 
Required Dividend
Coverage Ratio(c)
Actual Dividend
Coverage Ratio
Preferred Stock
Issuable
Ameren Missouri
>2.0
4.5

$
3,831

  
>2.5
116.5

$
2,228

Ameren Illinois
>2.0
6.8

3,565

(d) 
>1.5
2.4

203

(a)
Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.
(b)
Amount of bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include bonds issuable based on retired bond capacity of $729 million and $365 million at Ameren Missouri and Ameren Illinois, respectively.
(c)
Coverage required on the annual dividend on preferred stock outstanding and to be issued, as required in the respective company’s articles of incorporation.
(d)
Amount of bonds issuable by Ameren Illinois based on unfunded property additions and retired bonds solely under the former IP mortgage indenture.
Aggregate Principal Amount Of Maturities 
The following table sets forth the aggregate principal amount of each series of notes repurchased, along with certain other items related to the tender offer:
Senior Secured Notes
Principal Amount Repurchased
 
Premium Plus Accrued
and Unpaid Interest(a)
 
Principal Amount Outstanding After Tender Offer
6.00% senior secured notes due 2018
$
71

 
$
19

 
$
179

6.70% senior secured notes due 2019
121

 
35

 
329

5.10% senior secured notes due 2018
1

 
(b)

 
199

5.10% senior secured notes due 2019
56

 
12

 
244

(a)
The premiums paid in association with the tender offer were recorded as a regulatory asset and are being amortized over the life of the $485 million 3.90% senior secured notes due 2042.
(b)
Amount is less than $1 million.
Debt Redemption [Table Text Block] 
In January 2014, Ameren Illinois redeemed the following environmental improvement and pollution control revenue bonds at par value plus accrued interest:
Senior Secured Notes
Principal Amount
5.90% Series 1993 due 2023(a)
$
32

5.70% 1994A Series due 2024(a)
36

1993 Series C-1 5.95% due 2026
35

1993 Series C-2 5.70% due 2026
8

5.40% 1998A Series due 2028
19

5.40% 1998B Series due 2028
33

Total amount redeemed
$
163

(a)
Less than $1 million principal amount of the bonds remain outstanding as of January 31, 2014.
Aggregate Principal Amount Of Maturities 
The following table sets forth the aggregate principal amount of each series of notes repurchased, along with certain other items related to the tender offer:
Senior Secured Notes
Principal Amount Repurchased
 
Premium Plus Accrued
and Unpaid Interest(a)
 
Principal Amount Outstanding After Tender Offer
9.75% senior secured notes due 2018
$
87

 
$
36

 
$
313

6.25% senior secured notes due 2018
194

 
47

 
144

(a)
Premiums paid in the amount of $21 million in association with the tender offer were recorded as a regulatory asset and are being amortized over the life of the $400 million 2.70% senior secured notes due 2022.
Other Income And Expenses (Tables)
Other Income And Expenses
The following table presents the components of "Other Income and Expenses" in the Ameren Companies’ statements of income (loss) for the years ended December 31, 2013, 2012, and 2011:
 
2013
 
2012
 
2011
 
Ameren:(a)
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
37

 
$
36

 
$
34

 
Interest income on industrial development revenue bonds
27

 
28

 
28

 
Interest and dividend income
3

 
4

(b) 
3

 
Other
2

 
2

 
3

 
Total miscellaneous income
$
69

 
$
70

 
$
68

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
12

 
$
24

(c) 
$
8

 
Other
14

 
13

 
15

 
Total miscellaneous expense
$
26

 
$
37

 
$
23

 
Ameren Missouri:
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
31

 
$
31

 
$
30

 
Interest income on industrial development revenue bonds
27

 
28

 
28

 
Interest and dividend income
—

 
4

(b) 
2

 
Other
—

 
—

 
1

 
Total miscellaneous income
$
58

 
$
63

 
$
61

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
4

 
$
9

 
$
3

 
Other
7

 
5

 
7

 
Total miscellaneous expense
$
11

 
$
14

 
$
10

 
Ameren Illinois:
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
6

 
$
5

 
$
4

 
Interest and dividend income
2

 
—

 
1

 
Other
2

 
2

 
2

 
Total miscellaneous income
$
10

 
$
7

 
$
7

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
4

 
$
11

(c) 
$
1

 
Other
5

 
6

 
5

 
Total miscellaneous expense
$
9

 
$
17

 
$
6

 
(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
Includes interest income received in 2012 relating to a refund of charges included in an expired power purchase agreement with Entergy. See Note 2 – Rate and Regulatory Matters for additional information.
(c)
Includes Ameren Illinois' one-time $7.5 million donation to the Illinois Science and Energy Innovation Trust pursuant to the IEIMA as a result of Ameren Illinois' 2012 participation in the electric delivery formula ratemaking process.
Derivative Financial Instruments (Tables)
Open Gross Derivative Volumes By Commodity Type 
The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of December 31, 2013, and 2012. As of December 31, 2013, these contracts ran through October 2016, October 2019, May 2032, and October 2016 for fuel oils, natural gas, power, and uranium, respectively.
  
Quantity (in millions, except as indicated)
 
2013
2012
Commodity
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Fuel oils (in gallons)(a)
66
(b)
66
70
(b)
70
Natural gas (in mmbtu)
28
108
136
19
128
147
Power (in megawatthours)
3
11
14
11
14
25
Uranium (pounds in thousands)
796
(b)
796
446
(b)
446
 
 
 
 
 
 
 
 
 
 
 
 

(a)
Fuel oils consist of heating oil, ultra-low-sulfur diesel, and crude oil.
(b)
Not applicable.

Derivative Instruments Carrying Value 
The following table presents the carrying value and balance sheet location of all derivative instruments as of December 31, 2013, and 2012:
 
Balance Sheet Location
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2013
 
 
 
 
 
 
 
Derivative assets not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
Fuel oils
Other current assets
$
6

$
—

$
6

 
Other assets
 
3

 
—

 
3

Natural gas
Other current assets
 
1

 
1

 
2

Power
Other current assets
 
23

 
—

 
23

 
Total assets
$
33

$
1

$
34

Derivative liabilities not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
MTM derivative liabilities
$
(b)

$
—

$
2

 
Other current liabilities
 
2

 
—

 
—

 
Other deferred credits and liabilities
 
1

 
—

 
1

Natural gas
MTM derivative liabilities
 
(b)

 
27

 
32

 
Other current liabilities
 
5

 
—

 
—

 
Other deferred credits and liabilities
 
6

 
19

 
25

Power
MTM derivative liabilities
 
(b)

 
9

 
13

 
Other current liabilities
 
4

 
—

 
—

 
Other deferred credits and liabilities
 
—

 
99

 
99

Uranium
MTM derivative liabilities
 
(b)

 
—

 
5

 
Other current liabilities
 
5

 
—

 
—

 
Other deferred credits and liabilities
 
1

 
—

 
1

 
Total liabilities
$
24

$
154

$
178

2012
 
 
 
 
 
 
 
Derivative assets not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current assets
$
8

$
—

$
8

 
Other assets
 
4

 
—

 
4

Natural gas
Other current assets
 
—

 
1

 
1

 
Other assets
 
1

 
—

 
1

Power
Other current assets
 
14

 
—

 
14

 
Other assets
 
1

 
—

 
1

 
Total assets
$
28

$
1

$
29

Derivative liabilities not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
MTM derivative liabilities
$
(b)

$
—

$
2

 
Other current liabilities
 
2

 
—

 
—

 
Other deferred credits and liabilities
 
2

 
—

 
2

Natural gas
MTM derivative liabilities
 
(b)

 
56

 
64

 
Other current liabilities
 
8

 
—

 
—

 
Other deferred credits and liabilities
 
7

 
38

 
45

Power
MTM derivative liabilities
 
(b)

 
21

 
25

 
Other current liabilities
 
4

 
—

 
—

 
Other deferred credits and liabilities
 
—

 
90

 
90

Uranium
MTM derivative liabilities
 
(b)

 
—

 
1

 
Other current liabilities
 
1

 
—

 
—

 
Other deferred credits and liabilities
 
1

 
—

 
1

 
Total liabilities
$
25

$
205

$
230

(a)
Includes derivatives subject to regulatory deferral.
(b)
Balance sheet line item not applicable to registrant.

Cumulative Pretax Net Gains (Losses) On All Derivative Instruments In OCI 
The following table presents the cumulative amount of pretax net gains (losses) on all derivative instruments deferred in regulatory assets or regulatory liabilities as of December 31, 2013, and 2012:
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2013
 
 
 
 
 
 
Cumulative gains (losses) deferred in regulatory liabilities or assets:
 
 
 
 
 
 
Fuel oils derivative contracts(a)
$
2

$
—

$
2

Natural gas derivative contracts(b)
 
(10
)
 
(45
)
 
(55
)
Power derivative contracts(c)
 
19

 
(108
)
 
(89
)
Uranium derivative contracts(d)
 
(6
)
 
—

 
(6
)
2012
 
 
 
 
 
 
Cumulative gains (losses) deferred in regulatory liabilities or assets:
 
 
 
 
 
 
Fuel oils derivative contracts(a)
$
4

$
—

$
4

Natural gas derivative contracts(b)
 
(14
)
 
(93
)
 
(107
)
Power derivative contracts(c)
 
12

 
(111
)
 
(99
)
Uranium derivative contracts(d)
 
(2
)
 
—

 
(2
)


(a)
Represents net gains on fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s transportation costs for coal through October 2016, as of December 31, 2013. Current gains deferred as regulatory liabilities include $3 million and $3 million at Ameren and Ameren Missouri as of December 31, 2013, respectively. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri as of December 31, 2013, respectively.
(b)
Represents net losses associated with natural gas derivative contracts. These contracts are a partial hedge of natural gas requirements through October 2019 at Ameren and Ameren Missouri and through March 2017 at Ameren Illinois, in each case as of December 31, 2013. Current gains deferred as regulatory liabilities include $2 million, $1 million, and $1 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2013. Current losses deferred as regulatory assets include $32 million, $5 million, and $27 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2013.
(c)
Represents net gains (losses) associated with power derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri, in each case as of December 31, 2013. Current gains deferred as regulatory liabilities include $23 million and $23 million at Ameren and Ameren Missouri, respectively, as of December 31, 2013. Current losses deferred as regulatory assets include $13 million, $4 million, and $9 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of December 31, 2013.
(d)
Represents net losses on uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri's uranium requirements through October 2016, as of December 31, 2013. Current losses deferred as regulatory assets include $5 million and $5 million at Ameren and Ameren Missouri as of December 31, 2013, respectively.
Derivative Instruments With Credit Risk-Related Contingent Features 
The following table presents, as of December 31, 2013, and 2012, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a gross liability position, the cash collateral posted, and the aggregate amount of additional collateral that could be required to be posted with counterparties. The additional collateral required is the net liability position allowed under the master trading and netting agreements assuming (1) the credit risk-related contingent features underlying these agreements were triggered on December 31, 2013, or 2012, respectively, and (2) those counterparties with rights to do so requested collateral:
 
Aggregate Fair Value of
Derivative Liabilities(a)
 
Cash
Collateral Posted
 
Potential Aggregate Amount of
Additional Collateral Required(b)
2013
 
 
 
 
 
Ameren Missouri
$
70

 
$
2

 
$
67

Ameren Illinois
75

 
15

 
55

Ameren
$
145

 
$
17

 
$
122

2012
 
 
 
 
 
Ameren Missouri
$
78

 
$
3

 
$
71

Ameren Illinois
148

 
58

 
84

Ameren
$
226

 
$
61

 
$
155

(a)
Prior to consideration of master trading and netting agreements and including NPNS and accrual contract exposures.
(b)
As collateral requirements with certain counterparties are based on master trading and netting agreements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such agreements.

Derivatives That Qualify For Regulatory Deferral 
The following table represents the net change in market value associated with derivatives that qualify for regulatory deferral for the years ended December 31, 2013 and 2012:
  
 
Gain (Loss) Recognized
in Regulatory Liabilities
or Regulatory Assets
2013
 
2012
Ameren (a)
Fuel oils
 
$
(2
)
 
$
(15
)
 
Natural gas
 
52

 
84

 
Power
 
10

 
(180
)
 
Uranium
 
(4
)
 
(1
)
 
Total
 
$
56

 
$
(112
)
Ameren Missouri
Fuel oils
 
$
(2
)
 
$
(15
)
 
Natural gas
 
4

 
10

 
Power
 
7

 
(9
)
 
Uranium
 
(4
)
 
(1
)
 
Total
 
$
5

 
$
(15
)
Ameren Illinois
Natural gas
 
$
48

 
$
74

 
Power
 
3

 
29

 
Total
 
$
51

 
$
103

(a)
Amounts include intercompany eliminations.
Offsetting Derivative Assets and Liabilities [Table Text Block] 
The following table provides the recognized gross derivative balances and the net amounts of those derivatives subject to an enforceable master netting arrangement or similar agreement as of December 31, 2013, and 2012:
 
 
 
 
Gross Amounts Not Offset in the Balance Sheet
 
 
 
 
Gross Amounts Recognized in the Balance Sheet
 
Derivative Instruments
 
Cash Collateral Received/Posted(a)
 
Net
Amount
2013
 
 
 
 
 
 
 
 
Commodity contracts eligible to be offset:
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
$
33

$
9

$
—

$
24

Ameren Illinois
 
1

 
1

 
—

 
—

Ameren
$
34

$
10

$
—

$
24

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
$
24

$
9

$
9

$
6

Ameren Illinois
 
154

 
1

 
15

 
138

Ameren
$
178

$
10

$
24

$
144

2012
 
 
 
 
 
 
 
 
Commodity contracts eligible to be offset:
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
$
28

$
9

$
—

$
19

Ameren Illinois
 
1

 
1

 
—

 
—

Ameren
$
29

$
10

$
—

$
19

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
$
25

$
9

$
7

$
9

Ameren Illinois
 
205

 
1

 
58

 
146

Ameren
$
230

$
10

$
65

$
155

(a)
Cash collateral received reduces gross asset balances and is included in “Other current liabilities” and “Other deferred credits and liabilities” on the balance sheet. Cash collateral posted reduces gross liability balances and is included in “Other current assets” and “Other assets” on the balance sheet.
Fair Value Measurements (Tables)
Fair Value Inputs, Assets and Liabilities, Quantitative Information 
The following table describes the valuation techniques and unobservable inputs for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the period ended December 31, 2013:
 
 
Fair Value
 
 
 
Weighted
 
 
Assets
Liabilities
Valuation Technique(s)
Unobservable Input
Range
Average
Level 3 Derivative asset and liability – commodity contracts(a):
 
 
 
Ameren
Fuel oils
$
8

$
(3
)
Option model
Volatilities(%)(b)
10 - 35
16
 
 
 
 
Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.26 - 2
1
 
Power(e)
21

(110
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)
25 - 51
32
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(1,594) - 945
305
 
 
 
 
 
Nodal basis($/MWh)(c)
(3) - (1)
(2)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.39 - 0.50
0.42
 
 
 
 
 
Ameren credit risk(%)(c)(d)
2
(f)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 5
5
 
 
 
 
 
Escalation rate(%)(b)(g)
3 - 4
4
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
 
Uranium
—

(6
)
Discounted cash flow
Average bid/ask consensus pricing($/pound)(b)
34 - 41
36
Ameren Missouri
Fuel oils
$
8

$
(3
)
Option model
Volatilities(%)(b)
10 - 35
16
 
 
 
 
Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.26 - 2
1
 
Power(e)
21

(2
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)
25 - 51
40
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(1,594) - 945
305
 
 
 
 
 
Nodal basis($/MWh)(c)
(3) - (1)
(2)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.39 - 0.50
0.42
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
2
(f)
 
Uranium
—

(6
)
Discounted cash flow
Average bid/ask consensus pricing($/pound)(b)
34 - 41
36
Ameren Illinois
Power(e)
$
—

$
(108
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(b)
27 - 36
30
 
 
 
 
 
Nodal basis($/MWh)(b)
(4) - 0
(2)
 
 
 
 
 
Ameren Illinois credit risk(%)(c)(d)
2
(f)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 5
5
 
 
 
 
 
Escalation rate(%)(b)(g)
3 - 4
4
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(c)
Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.
(d)
Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren, Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(e)
Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2017. Valuations beyond 2017 use fundamentally modeled pricing by month for peak and off-peak demand.
(f)
Not applicable.
(g)
Escalation rate applies to power prices 2026 and beyond.

The following table describes the valuation techniques and unobservable inputs for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2012:
 
 
Fair Value
 
 
 
Weighted
 
 
Assets
Liabilities
Valuation Technique
Unobservable Input
Range
Average
Level 3 Derivative asset and liability – commodity contracts(a):
 
 
 
Ameren
Fuel oils
$
8

$
(3
)
Option model
Volatilities(%)(b)
7 - 27
24
 
 
 
 
Discounted cash flow
Escalation rate(%)(b)
0.21 - 0.60
0.44
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.12 - 1
1
 
 
 
 
 
Ameren credit risk(%)(c)(d)
2
(e)
 
Power(f)
14

(114
)
Discounted cash flow
Average forward peak and off-peak power pricing - forwards/swaps($/MWh)(c)
22 - 47
31
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(281) - 1,851
178
 
 
 
 
 
Nodal basis($/MWh)(c)
(5) - (1)
(3)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.22 - 1
1
 
 
 
 
 
Ameren credit risk(%)(c)(d)
2 - 5
5
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 8
6
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
 
Uranium
—

(2
)
Discounted cash flow
Average forward uranium pricing($/pound)(b)
43 - 46
44
Ameren Missouri
Fuel oils
$
8

$
(3
)
Option model
Volatilities(%)(b)
7 - 27
24
 
 
 
 
Discounted cash flow
Escalation rate(%)(b)
0.21 - 0.60
0.44
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.12 - 1
1
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
2
(e)
 
Power(f)
14

(3
)
Discounted cash flow
Average forward peak and off-peak power pricing - forwards/swaps($/MWh)(c)
24 - 56
36
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(281) - 1,851
178
 
 
 
 
 
Nodal basis($/MWh)(c)
(5) - (1)
(2)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.22 - 1
1
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
2
(e)
 
Uranium
—

(2
)
Discounted cash flow
Average forward uranium pricing($/pound)(b)
43 - 46
44
Ameren Illinois
Power(f)
$
—

$
(111
)
Discounted cash flow
Average forward peak and off-peak power pricing - forwards/swaps($/MWh)(b)
22 - 47
30
 
 
 
 
 
Nodal basis($/MWh)(b)
(5) - (1)
(3)
 
 
 
 
 
Ameren Illinois credit risk(%)(c)(d)
5
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 8
6
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(c)
Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.
(d)
Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren, Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(e)
Not applicable.
(f)
Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2017. Valuations beyond 2017 use fundamentally modeled pricing by month for peak and off-peak demand.
Schedule Of Fair Value Hierarchy Of Assets And Liabilities Measured At Fair Value On Recurring Basis 
The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2013:
 
 
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Assets:
 
 
 
 
 
 
 
 
 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
1

 
$
—

 
$
8

 
$
9

 
Natural gas
 
—

 
2

 
—

 
2

 
Power
 
—

 
2

 
21

 
23

 
Total derivative assets – commodity contracts
 
$
1

 
$
4

 
$
29

 
$
34

 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
3

 
$
—

 
$
—

 
$
3

 
Equity securities:
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
332

 
—

 
—

 
332

 
Debt securities:
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
52

 
—

 
52

 
Municipal bonds
 
—

 
2

 
—

 
2

 
U.S. treasury and agency securities
 
—

 
94

 
—

 
94

 
Asset-backed securities
 
—

 
10

 
—

 
10

 
Other
 
—

 
1

 
—

 
1

 
Total nuclear decommissioning trust fund
 
$
335

 
$
159

 
$
—

 
$
494

 
Total Ameren
 
$
336

 
$
163

 
$
29

 
$
528

Ameren Missouri
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
1

 
$
—

 
$
8

 
$
9

 
Natural gas
 
—

 
1

 
—

 
1

 
Power
 
—

 
2

 
21

 
23

 
Total derivative assets – commodity contracts
 
$
1

 
$
3

 
$
29

 
$
33

 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
3

 
$
—

 
$
—

 
$
3

 
Equity securities:
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
332

 
—

 
—

 
332

 
Debt securities:
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
52

 
—

 
52

 
Municipal bonds
 
—

 
2

 
—

 
2

 
U.S. treasury and agency securities
 
—

 
94

 
—

 
94

 
Asset-backed securities
 
—

 
10

 
—

 
10

 
Other
 
—

 
1

 
—

 
1

 
Total nuclear decommissioning trust fund
 
$
335

 
$
159

 
$
—

 
$
494

 
Total Ameren Missouri
 
$
336

 
$
162

 
$
29

 
$
527

Ameren Illinois
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
1

 
$
—

 
$
1

Liabilities:
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
—

 
$
—

 
$
3

 
$
3

 
Natural gas
 
3

 
54

 
—

 
57

 
Power
 
—

 
2

 
110

 
112

 
Uranium
 
—

 
—

 
6

 
6

 
Total Ameren
 
$
3

 
$
56

 
$
119

 
$
178

Ameren Missouri
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
—

 
$
—

 
$
3

 
$
3

 
Natural gas
 
3

 
8

 
—

 
11

 
Power
 
—

 
2

 
2

 
4

 
Uranium
 
—

 
—

 
6

 
6

 
Total Ameren Missouri
 
$
3

 
$
10

 
$
11

 
$
24

Ameren Illinois
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
46

 
$
—

 
$
46

 
Power
 
—

 
—

 
108

 
108

 
Total Ameren Illinois
 
$
—

 
$
46

 
$
108

 
$
154

(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2012:
 
 
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant
Other
Unobservable
Inputs
(Level 3)
 
Total
 
Assets:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
4

 
$
—

 
$
8

 
$
12

 
 
Natural gas
 
—

 
2

 
—

 
2

 
 
Power
 
—

 
1

 
14

 
15

 
 
Total derivative assets – commodity contracts
 
$
4

 
$
3

 
$
22

 
$
29

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
264

 
—

 
—

 
264

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
47

 
—

 
47

 
 
Municipal bonds
 
—

 
1

 
—

 
1

 
 
U.S. treasury and agency securities
 
—

 
81

 
—

 
81

 
 
Asset-backed securities
 
—

 
11

 
—

 
11

 
 
Other
 
—

 
1

 
—

 
1

 
 
Total nuclear decommissioning trust fund
 
$
265

 
$
141

 
$
—

 
$
406

(b) 
 
Total Ameren
 
$
269

 
$
144

 
$
22

 
$
435

 
Ameren Missouri
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
4

 
$
—

 
$
8

 
$
12

 
 
Natural gas
 
—

 
1

 
—

 
1

 
 
Power
 
—

 
1

 
14

 
15

 
 
Total derivative assets – commodity contracts
 
$
4

 
$
2

 
$
22

 
$
28

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
264

 
—

 
—

 
264

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
47

 
—

 
47

 
 
Municipal bonds
 
—

 
1

 
—

 
1

 
 
U.S. treasury and agency securities
 
—

 
81

 
—

 
81

 
 
Asset-backed securities
 
—

 
11

 
—

 
11

 
 
Other
 
—

 
1

 
—

 
1

 
 
Total nuclear decommissioning trust fund
 
$
265

 
$
141

 
$
—

 
$
406

(b) 
 
Total Ameren Missouri
 
$
269

 
$
143

 
$
22

 
$
434

 
Ameren Illinois
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
1

 
$
—

 
$
1

 
Liabilities:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
1

 
$
—

 
$
3

 
$
4

 
 
Natural gas
 
7

 
102

 
—

 
109

 
 
Power
 
—

 
1

 
114

 
115

 
 
Uranium
 
—

 
—

 
2

 
2

 
 
Total Ameren
 
$
8

 
$
103

 
$
119

 
$
230

 
Ameren Missouri
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
1

 
$
—

 
$
3

 
$
4

 
 
Natural gas
 
7

 
8

 
—

 
15

 
 
Power
 
—

 
1

 
3

 
4

 
 
Uranium
 
—

 
—

 
2

 
2

 
 
Total Ameren Missouri
 
$
8

 
$
9

 
$
8

 
$
25

 
Ameren Illinois
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
94

 
$
—

 
$
94

 
 
Power
 
—

 
—

 
111

 
111

 
 
Total Ameren Illinois
 
$
—

 
$
94

 
$
111

 
$
205

 
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Balance excludes $2 million of receivables, payables, and accrued income, net.
Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level 3 In The Fair Value Hierarchy 
The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2013:
  
 
Net Derivative Commodity Contracts
  
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
5

$
(a)

$
5

Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
—

 
(a)

 
—

Total realized and unrealized gains (losses)
 
—

 
(a)

 
—

Purchases
 
3

 
(a)

 
3

Sales
 
(1
)
 
(a)

 
(1
)
Settlements
 
(2
)
 
(a)

 
(2
)
Ending balance at December 31, 2013
$
5

$
(a)

$
5

Change in unrealized gains (losses) related to assets/liabilities held at December 31,2013
$
—

$
(a)

$
—

Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
—

$
—

$
—

Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
—

 
(1
)
 
(1
)
Total realized and unrealized gains (losses)
 
—

 
(1
)
 
(1
)
Purchases
 
—

 
1

 
1

Ending balance at December 31, 2013
$
—

$
—

$
—

Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013
$
—

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
11

$
(111
)
$
(100
)
Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
3

 
(18
)
 
(15
)
Total realized and unrealized gains (losses)
 
3

 
(18
)
 
(15
)
Purchases
 
40

 
—

 
40

Settlements
 
(36
)
 
21

 
(15
)
Transfers into Level 3
 
(3
)
 
—

 
(3
)
Transfers out of Level 3
 
4

 
—

 
4

Ending balance at December 31, 2013
$
19

$
(108
)
$
(89
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013
$
(1
)
$
(24
)
 $
(25
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
(2
)
$
(a)

$
(2
)
Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
(3
)
 
(a)

 
(3
)
Total realized and unrealized gains (losses)
 
(3
)
 
(a)

 
(3
)
Purchases
 
(2
)
 
(a)

 
(2
)
Settlements
 
1

 
(a)

 
1

Ending balance at December 31, 2013
$
(6
)
$
(a)

$
(6
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013
$
(2
)
$
(a)

$
(2
)

(a)
Not applicable.
The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2012:
  
 
Net Derivative Commodity Contracts
  
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2012
$
3

$
(a)

$
3

Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
(1
)
 
(a)

 
(1
)
Total realized and unrealized gains (losses)
 
(1
)
 
(a)

 
(1
)
Purchases
 
7

 
(a)

 
7

Sales
 
(3
)
 
(a)

 
(3
)
Settlements
 
(2
)
 
(a)

 
(2
)
Transfers into Level 3
 
1

 
(a)

 
1

Ending balance at December 31, 2012
$
5

$
(a)

$
5

Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2012
$
(1
)
$
(a)

$
(1
)
Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2012
$
(14
)
$
(160
)
$
(174
)
Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
(2
)
 
(25
)
 
(27
)
Total realized and unrealized gains (losses)
 
(2
)
 
(25
)
 
(27
)
Settlements
 
1

 
15

 
16

Transfers out of Level 3
 
15

 
170

 
185

Ending balance at December 31, 2012
$
—

$
—

$
—

Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2012
$
—

$
—

$
—

Power(b):
 
 
 
 
 
 
Beginning balance at January 1, 2012
$
21

$
(140
)
$
81

Realized and unrealized gains (losses):
 
 
 
 
 

Included in regulatory assets/liabilities
 
11

 
(226
)
 
(175
)
Total realized and unrealized gains (losses)
 
11

 
(226
)
 
(175
)
Purchases
 
21

 
—

 
21

Sales
 
(1
)
 
—

 
(1
)
Settlements
 
(37
)
 
255

 
(22
)
Transfers out of Level 3
 
(4
)
 
—

 
(4
)
Ending balance at December 31, 2012
$
11

$
(111
)
$
(100
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2012
$
—

$
(191
)
(c) $
(175
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2012
$
(1
)
$
(a)

$
(1
)
Realized and unrealized gains (losses):
 
 
 
 
 
 
Included in regulatory assets/liabilities
 
(2
)
 
(a)

 
(2
)
Total realized and unrealized gains (losses)
 
(2
)
 
(a)

 
(2
)
Settlements
 
1

 
(a)

 
1

Ending balance at December 31, 2012
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2012
$
(1
)
$
(a)

$
(1
)
(a)
Not applicable.
(b)
Ameren amounts include intercompany eliminations.
(c)
The change in unrealized losses was due to decreases in long-term power prices applied to 20-year Ameren Illinois swap contracts, which expire in May 2032.
Schedule Of Transfers Between Fair Value Hierarchy Levels 
The following table summarizes all transfers between fair value hierarchy levels related to derivative commodity contracts for the years ended December 31, 2013 and 2012:
 
2013
 
2012
Ameren - derivative commodity contracts:



Transfers into Level 3 / Transfers out of Level 1 – Fuel oils
$
—

 
$
1

Transfers out of Level 3 / Transfers into Level 2 – Natural gas
—

 
185

Transfers into Level 3 / Transfers out of Level 2 – Power
(3
)
 
—

Transfers out of Level 3 / Transfers into Level 2 – Power
4

 
(4
)
Net fair value of Level 3 transfers
$
1

 
$
182

Ameren Missouri - derivative commodity contracts:
 
 
 
Transfers into Level 3 / Transfers out of Level 1 – Fuel oils
$
—

 
$
1

Transfers out of Level 3 / Transfers into Level 2 – Natural gas
—

 
15

Transfers into Level 3 / Transfers out of Level 2 – Power
(3
)
 
—

Transfers out of Level 3 / Transfers into Level 2 – Power
4

 
(4
)
Net fair value of Level 3 transfers
$
1

 
$
12

Ameren Illinois - derivative commodity contracts:
 
 
 
 Transfers out of Level 3 / Transfers into Level 2 – Natural gas
$
—

 
$
170


Schedule Of Carrying Amounts And Estimated Fair Values Of Long-Term Debt And Preferred Stock 
The following table presents the carrying amounts and estimated fair values of our long-term debt and preferred stock at December 31, 2013 and 2012:
  
2013
 
2012
  
Carrying Amount
 
Fair Value
 
Carrying Amount
 
Fair Value
Ameren:(a)
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
6,038

 
$
6,584

 
$
6,157

 
$
7,110

Preferred stock
142

 
118

 
142

 
123

Ameren Missouri:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
3,757

 
$
4,124

 
$
4,006

 
$
4,625

Preferred stock
80

 
71

 
80

 
74

Ameren Illinois:
 
 
 
 
 
 
 
Long-term debt (including current portion)
$
1,856

 
$
2,028

 
$
1,727

 
$
2,020

Preferred stock
62

 
47

 
62

 
49

(a)
Preferred stock is recorded in "Noncontrolling Interests" on the consolidated balance sheet.
Nuclear Decommissioning Trust Fund Investments (Tables)
Fair Value Of Securities In Nuclear Decommissioning Trust Fund 
The following table presents the costs and fair values of investments in debt and equity securities in Ameren Missouri’s nuclear decommissioning trust fund at December 31, 2013, and 2012:
Security Type
Cost
 
Gross Unrealized Gain
 
Gross Unrealized Loss
 
Fair Value
2013
 
 
 
 
 
 
 
Debt securities
$
157

 
$
4

$
2

 
$
159

Equity securities
137

 
199

 
4

 
332

Cash
3

 
—

 
—

 
3

Other(b)
(a)

 
—

 
—

 
(a)

Total
$
297

 
$
203

$
6

 
$
494

2012
 
 
 
 
 
 
 
Debt securities
$
133

 
$
8

$
(a)

 
$
141

Equity securities
145

 
130

 
11

 
264

Cash
1

 
—

 
—

 
1

Other(b)
2

 
—

 
—

 
2

Total
$
281

 
$
138

$
11

 
$
408

(a)
Amount less than $1 million.
(b)
Represents payables relating to pending security purchases, net of receivables related to pending security sales and interest receivables.
Schedule Of Unrealized Losses On Available-For-Sale Investments Included In Nuclear Decommissioning Trust Fund 
They are aggregated by investment category and the length of time that individual securities have been in a continuous unrealized loss position at December 31, 2013:
  
Less than 12 Months
 
 
12 Months or Greater
 
Total
  
Fair Value
 
Gross
Unrealized
Losses
 
 
Fair Value
 
Gross
Unrealized
Losses
 
Fair Value
 
Gross
Unrealized
Losses
Debt securities
$
72

 
$
2

 
$
(a)

$
(a)

 
$
72

 
$
2

Equity securities
6

 
(a)

 
 
7

 
4

 
13

 
4

Total
$
78

 
$
2

 
$
7

$
4

 
$
85

 
$
6

(a)
Amount less than $1 million.
Proceeds From Sale Of Investments In Nuclear Decommissioning Trust Fund And Gross Realized Gains And Losses 
The following table presents proceeds from the sale and maturities of investments in Ameren Missouri’s nuclear decommissioning trust fund and the gross realized gains and losses resulting from those sales for the years ended December 31, 2013, 2012, and 2011:
 
2013
 
2012
 
2011
Proceeds from sales and maturities
$
196

 
$
384

 
$
199

Gross realized gains
7

 
6

 
5

Gross realized losses
5

 
2

 
4

Fair Value Of Securities In Nuclear Decommissioning Trust Fund According To Their Contractual Maturities 
The following table presents the costs and fair values of investments in debt securities in Ameren Missouri’s nuclear decommissioning trust fund according to their contractual maturities at December 31, 2013:
 
Cost
 
Fair Value
Less than 5 years
$
93

 
$
94

5 years to 10 years
31

 
32

Due after 10 years
33

 
33

Total
$
157

 
$
159

Retirement Benefits (Tables)
Summary Of Benefit Liability Recorded 
The following table presents the net benefit liability recorded on the balance sheets of each of the Ameren Companies as of December 31, 2013, and 2012:
 
2013

2012

Ameren(a)
$
461

$
1,143

Ameren Missouri
191

464

Ameren Illinois
198

408

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Funded Status Of Benefit Plans And Amounts Included In Regulatory Assets And OCI 
The following table presents the funded status of our pension and postretirement benefit plans as of December 31, 2013, and 2012. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 2013, and 2012, that have not been recognized in net periodic benefit costs.
  
2013
 
2012
  
Pension Benefits(a)
 
Postretirement
Benefits(a)
 
Pension Benefits(a)
 
Postretirement
Benefits(a)
Accumulated benefit obligation at end of year
$
3,698

$
(b)

 
$
3,829

$
(b)

Change in benefit obligation:
 
 
 
 
 
 
 
Net benefit obligation at beginning of year
$
4,051

$
1,157

 
$
3,764

$
1,145

Service cost
91

 
22

 
81

 
22

Interest cost
163

 
46

 
166

 
47

Participant contributions
—

 
16

 
—

 
16

Actuarial (gain) loss
(207
)
 
(76
)
 
240

 
(10
)
Curtailment gain(c)
—

 
(3
)
 
—

 
—

Settlement(d)
—

 
(5
)
 
—

 
—

Benefits paid
(198
)
 
(64
)
 
(200
)
 
(69
)
Early retiree reinsurance program receipt
(b)

 
—

 
(b)

 
2

Federal subsidy on benefits paid
(b)

 
3

 
(b)

 
4

Net benefit obligation at end of year
3,900

 
1,096

 
4,051

 
1,157

Change in plan assets:
 
 
 
 
 
 
 
Fair value of plan assets at beginning of year
3,127

 
938

 
2,814

 
836

Actual return on plan assets
376

 
156

 
385

 
104

Employer contributions
156

 
25

 
128

 
45

Federal subsidy on benefits paid
(b)

 
3

 
(b)

 
4

Early retiree reinsurance program receipt
(b)

 
—

 
(b)

 
2

Participant contributions
—

 
16

 
—

 
16

Benefits paid
(198
)
 
(64
)
 
(200
)
 
(69
)
Fair value of plan assets at end of year
3,461

 
1,074

 
3,127

 
938

Funded status – deficiency
439

 
22

 
924

 
219

Accrued benefit cost at December 31
$
439

$
22

 
$
924

$
219

Amounts recognized in the balance sheet consist of:
 
 
 
 
 
 
 
Noncurrent asset(e)
$
—

$
(9
)
 
$
—

$
—

Current liability(f)
3

 
1

 
3

 
2

Noncurrent liability
436

 
30

 
921

 
217

Net liability recognized
$
439

$
22

 
$
924

$
219

Amounts recognized in regulatory assets consist of:
 
 
 
 
 
 
 
Net actuarial (gain) loss
$
282

$
(71
)
 
$
699

$
103

Prior service cost (credit)
(7
)
 
(20
)
 
(6
)
 
(24
)
Amounts (pretax) recognized in accumulated OCI consist of:
 
 
 
 
 
 
 
Net actuarial (gain) loss
17

 
(12
)
 
65

 
5

Prior service cost (credit)
—

 
(1
)
 
(14
)
 
(6
)
Total
$
292

$
(104
)
 
$
744

$
78

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
Not applicable.
Assumptions Used To Determine Benefit Obligations 
The following table presents the assumptions used to determine our benefit obligations at December 31, 2013, and 2012:
  
Pension Benefits
 
Postretirement Benefits
  
2013
 
2012
 
2013
 
2012
Discount rate at measurement date
4.75
%
 
4.00
%
 
4.75
%
 
4.00
%
Increase in future compensation
3.50

 
3.50

 
3.50

 
3.50

Medical cost trend rate (initial)
—

 
—

 
5.00

 
5.00

Medical cost trend rate (ultimate)
—

 
—

 
5.00

 
5.00

Years to ultimate rate
—

 
—

 
—

 
—

Schedule Of Cash Contributions Made To Benefit Plans 
The following table presents the cash contributions made to our defined benefit retirement plan and to our postretirement plans during 2013, 2012, and 2011:
  
Pension Benefits
 
Postretirement Benefits
  
2013
 
2012
 
2011
 
2013
 
2012
 
2011
Ameren Missouri
$
60

 
$
52

 
$
43

 
$
10

 
$
9

 
$
9

Ameren Illinois
50

 
46

 
28

 
11

 
35

 
118

Other
46

 
30

 
25

 
4

 
1

 
2

Ameren(a)
156

 
128

 
96

 
25

 
45

 
129

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Target Allocation Of The Plans' Asset Categories 
The following table presents our target allocations for 2014 and our pension and postretirement plans’ asset categories as of December 31, 2013, and 2012.
Asset
Category
Target Allocation
2014
 
Percentage of Plan Assets at December  31,
2013
 
2012
Pension Plan:
 
 
 
 
 
Cash and cash equivalents
0 - 5  %
 
2
%
 
2
%
Equity securities:
 
 
 
 
 
U.S. large capitalization
29 - 39
 
36

 
34
%
U.S. small and mid-capitalization
2 - 12
 
8

 
7
%
International and emerging markets
9 - 19
 
14

 
13
%
Total equity
50 - 60
 
58

 
54
%
Debt securities
35 - 45
 
36

 
39
%
Real estate
0 -   9  
 
4

 
4
%
Private equity
0 -   4  
 
(a)

 
1
%
Total
 
 
100
%
 
100
%
Postretirement Plans:
 
 
 
 
 
Cash and cash equivalents
0 - 10 %
 
4
%
 
4
%
Equity securities:
 
 
 
 
 
U.S. large capitalization
33 - 43
 
41
%
 
40
%
U.S. small and mid-capitalization
3 - 13
 
8
%
 
8
%
International
10 - 20
 
14
%
 
14
%
Total equity
55 - 65
 
63
%
 
62
%
Debt securities
30 - 40
 
33
%
 
34
%
Total
 
 
100
%
 
100
%
Changes In The Fair Value Of Plan Assets Classified As Level 3 
The following table summarizes the changes in the fair value of the pension plan assets classified as Level 3 in the fair value hierarchy for each of the years ended December 31, 2013, and 2012:
 
Beginning
Balance at
January 1,
 
Actual Return on
Plan Assets Related
to Assets Still Held
at the Reporting Date
 
Actual Return on
Plan Assets Related
to Assets Sold
During the Period
 
Purchases,
Sales, and
Settlements, Net
 
Net
Transfers
into (out of)
of Level 3
 
Ending Balance at
December 31,
2013:
 
 
 
 
 
 
 
 
 
 
 
Real estate
$
118

 
$
9

 
$
—

 
$
4

 
$
—

 
$
131

Private equity
19

 
(9
)
 
11

 
(6
)
 
—

 
15

2012:
 
 
 
 
 
 
 
 
 
 
 
Real estate
$
108

 
$
7

 
$
—

 
$
3

 
$
—

 
$
118

Private equity
23

 
(7
)
 
8

 
(5
)
 
—

 
19

Components Of Net Periodic Benefit Cost 
The following table presents the components of the net periodic benefit cost of our pension and postretirement benefit plans during 2013, 2012, and 2011:
 
Pension Benefits
Ameren(a)
 
Postretirement Benefits
Ameren(a)
2013
 
 
 
Service cost
$
91

 
$
22

Interest cost
163

 
46

Expected return on plan assets
(218
)
 
(62
)
Amortization of:
 
 
 
Transition obligation
—

 
—

Prior service cost
(2
)
 
(6
)
Actuarial loss
87

 
8

Curtailment gain
(12
)
 
(7
)
Net periodic benefit cost(b)
$
109

 
$
1

2012
 
 
 
Service cost
$
81

 
$
22

Interest cost
166

 
47

Expected return on plan assets
(208
)
 
(56
)
Amortization of:
 
 
 
Transition obligation
—

 
2

Prior service cost
(3
)
 
(6
)
Actuarial loss
75

 
5

Net periodic benefit cost(c)
$
111

 
$
14

2011
 
 
 
Service cost
$
73

 
$
20

Interest cost
175

 
54

Expected return on plan assets
(211
)
 
(50
)
Amortization of:
 
 
 
Transition obligation
—

 
2

Prior service cost
(1
)
 
(6
)
Actuarial loss
41

 
3

Net periodic benefit cost(c)
$
77

 
$
23

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Summary Of Estimated Amortizable Amounts From Regulatory Assets and Accumulated OCI Into Net Periodic Benefit Cost 
The estimated amounts that will be amortized from regulatory assets and accumulated OCI into net periodic benefit cost in 2014 are as follows:
  
Pension Benefits
 
Postretirement Benefits
  
Ameren(a)
 
Ameren(a)
Regulatory assets:
 
 
 
Prior service cost (credit)
$
(1
)
 
$
(4
)
Net actuarial loss
60

 
9

Accumulated OCI:
 
 
 
Net actuarial (gain) loss
1

 
(2
)
Total
$
60

 
$
3

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Summary Of Benefit Plan Costs Incurred 
The Ameren Companies are responsible for their share of the pension and postretirement benefit costs. The following table presents the pension costs and the postretirement benefit costs incurred and included in continuing operations for the years ended December 31, 2013, 2012, and 2011:
  
Pension Costs
 
Postretirement Costs
  
2013
 
2012
 
2011
 
2013
 
2012
 
2011
Ameren Missouri
$
69

 
$
63

 
$
51

 
$
8

 
$
10

 
$
11

Ameren Illinois
41

 
37

 
16

 
—

 
4

 
11

Other
5

 
2

 
3

 
—

 
—

 
1

Ameren(a)
115

 
102

 
70

 
8

 
14

 
23

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Schedule Of Expected Payments From Qualified Trust And Company Funds 
The expected pension and postretirement benefit payments from qualified trust and company funds and the federal subsidy for postretirement benefits related to prescription drug benefits, which reflect expected future service, as of December 31, 2013, are as follows:
  
Pension Benefits
 
Postretirement Benefits
  
Paid from
Qualified
Trust
 
        Paid from
         Company
      Funds
 
        Paid from
         Qualified
      Trust
 
        Paid from
         Company
      Funds
 
        Federal
         Subsidy
2014
$
247

 
$
3

 
$
61

 
$
2

 
$
3

2015
249

 
3

 
63

 
2

 
4

2016
255

 
3

 
66

 
2

 
4

2017
260

 
3

 
69

 
2

 
4

2018
264

 
3

 
72

 
2

 
4

2019 - 2023
1,342

 
14

 
394

 
12

 
19

Assumptions Used To Determine Net Periodic Benefit Cost 
The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2013, 2012, and 2011:
  
Pension Benefits
 
Postretirement Benefits
  
2013
 
2012
 
2011
 
2013
 
2012
 
2011
Discount rate at measurement date
4.00
%
 
4.50
%
 
5.25
%
 
4.00
%
 
4.50
%
 
5.25
%
Expected return on plan assets
7.50

 
7.75

 
8.00

 
7.25

 
7.50

 
7.75

Increase in future compensation
3.50

 
3.50

 
3.50

 
3.50

 
3.50

 
3.50

Medical cost trend rate (initial)
—

 
—

 
—

 
5.00

 
5.50

 
6.00

Medical cost trend rate (ultimate)
—

 
—

 
—

 
5.00

 
5.00

 
5.00

Years to ultimate rate
—

 
—

 
—

 
—

 
1 year

 
2 years

Schedule Of Potential Changes In Key Assumptions 
The table below reflects the sensitivity of Ameren’s plans to potential changes in key assumptions:
  
Pension Benefits
 
Postretirement Benefits
  
Service Cost
and Interest
Cost
 
    Projected
    Benefit
     Obligation
 
    Service Cost
    and Interest
    Cost
 
    Postretirement
      Benefit
       Obligation
0.25% decrease in discount rate
$
(2
)
 
$
109

 
$
—

 
$
32

0.25% increase in salary scale
2

 
17

 
—

 
—

1.00% increase in annual medical trend
—

 
—

 
2

 
40

1.00% decrease in annual medical trend
—

 
—

 
(2
)
 
(37
)
Schedule Of Matching Contributions 
The following table presents the portion of the matching contribution to the Ameren 401(k) plan attributable to the continuing operations for each of the Ameren Companies for the years ended December 31, 2013, 2012, and 2011:
 
2013
 
2012
 
2011
Ameren Missouri
$
16

 
$
16

 
$
16

Ameren Illinois
10

 
9

 
8

Other
1

 
1

 
1

Ameren(a)
27

 
26

 
25

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Target Allocation Of The Plans' Asset Categories 
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2013:
 
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Cash and cash equivalents
$
5

 
$
39

 
$
—

 
$
44

Equity securities:
 
 
 
 
 
 
 
U.S. large capitalization
107

 
1,162

 
—

 
1,269

U.S. small and mid-capitalization
273

 
—

 
—

 
273

International and emerging markets
143

 
372

 
—

 
515

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
860

 
—

 
860

Municipal bonds
—

 
149

 
—

 
149

U.S. treasury and agency securities
—

 
256

 
—

 
256

Other
—

 
27

 
—

 
27

Real estate
—

 
—

 
131

 
131

Private equity
—

 
—

 
15

 
15

Derivative assets
1

 
—

 
—

 
1

Derivative liabilities
(1
)
 
—

 
—

 
(1
)
Total
$
528

 
$
2,865

 
$
146

 
$
3,539

Less: Medical benefit assets at December 31(a)
 
 
 
 
 
 
(112
)
Plus: Net receivables at December 31(b)
 
 
 
 
 
 
34

Fair value of pension plans assets at year end
 
 
 
 
 
 
$
3,461

(a)
Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation.
(b)
Receivables related to pending security sales, offset by payables related to pending security purchases.
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plan assets measured at fair value as of December 31, 2012:
 
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Cash and cash equivalents
$
1

 
$
28

 
$
—

 
$
29

Equity securities:
 
 
 
 
 
 
 
U.S. large capitalization
83

 
1,007

 
—

 
1,090

U.S. small and mid-capitalization
235

 
—

 
—

 
235

International and emerging markets
134

 
301

 
—

 
435

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
832

 
—

 
832

Municipal bonds
—

 
176

 
—

 
176

U.S. treasury and agency securities
—

 
250

 
—

 
250

Other
—

 
17

 
—

 
17

Real estate
—

 
—

 
118

 
118

Private equity
—

 
—

 
19

 
19

Derivative assets
—

 
—

 
—

 
—

Derivative liabilities
(1
)
 
—

 
—

 
(1
)
Total
$
452

 
$
2,611

 
$
137

 
$
3,200

Less: Medical benefit assets at December 31(a)
 
 
 
 
 
 
(102
)
Plus: Net receivables at December 31(b)
 
 
 
 
 
 
29

Fair value of pension plans assets at year end
 
 
 
 
 
 
$
3,127

(a)
Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation.
(b)
Receivables related to pending security sales, offset by payables related to pending security purchases.
Target Allocation Of The Plans' Asset Categories 
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2013:
 
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Cash and cash equivalents
$
77

 
$
—

 
$
—

 
$
77

Equity securities:
 
 
 
 
 
 
 
U.S. large capitalization
297

 
101

 
—

 
398

U.S. small and mid-capitalization
77

 
—

 
—

 
77

International
39

 
96

 
—

 
135

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
89

 
—

 
89

Municipal bonds
—

 
103

 
—

 
103

U.S. treasury and agency securities
—

 
72

 
—

 
72

Asset-backed securities
—

 
10

 
—

 
10

Other
—

 
40

 
—

 
40

Total
$
490

 
$
511

 
$
—

 
$
1,001

Plus: Medical benefit assets at December 31(a)
 
 
 
 
 
 
112

Less: Net payables at December 31(b)
 
 
 
 
 
 
(39
)
Fair value of postretirement benefit plans assets at year end
 
 
 
 
 
 
$
1,074

(a)
Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.
(b)
Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans assets measured at fair value as of December 31, 2012:
 
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
Cash and cash equivalents
$
83

 
$
—

 
$
—

 
$
83

Equity securities:
 
 
 
 
 
 
 
U.S. large capitalization
245

 
88

 
—

 
333

U.S. small and mid-capitalization
66

 
—

 
—

 
66

International
45

 
69

 
—

 
114

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
88

 
—

 
88

Municipal bonds
—

 
91

 
—

 
91

U.S. treasury and agency securities
—

 
67

 
—

 
67

Asset-backed securities
—

 
18

 
—

 
18

Other
—

 
22

 
—

 
22

Total
$
439

 
$
443

 
$
—

 
$
882

Plus: Medical benefit assets at December 31(a)
 
 
 
 
 
 
102

Less: Net payables at December 31(b)
 
 
 
 
 
 
(46
)
Fair value of postretirement benefit plans assets at year end
 
 
 
 
 
 
$
938

(a)
Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.
(b)
Payables related to pending security purchases, offset by Medicare, interest receivables, and receivables related to pending security sales.
Stock-Based Compensation (Tables)
Summary Of Nonvested Shares Related To Long-Term Incentive Plan
A summary of nonvested shares at December 31, 2013, and changes during the year ended December 31, 2013, under the 2006 Plan are presented below:
  
Performance Share Units
  
Share
Units
 
Weighted-average
Fair Value per Unit
Nonvested at January 1, 2013
1,192,487

 
$
33.56

Granted(a)
840,482

 
31.19

Unearned or forfeited(b)
(29,730
)
 
31.93

Earned and vested(c)
(784,695
)
 
31.60

Nonvested at December 31, 2013
1,218,544

 
$
33.23

(a)
Includes performance share units (share units) granted to certain executive and nonexecutive officers and other eligible employees in 2013 under the 2006 Plan.
(b)
Includes share units granted in 2011 that were not earned based on performance provisions of the award grants.
(c)
Includes share units granted in 2011 that vested as of December 31, 2013, that were earned pursuant to the provisions of the award grants. Also includes share units that vested due to attainment of retirement eligibility by certain employees and certain employees whose employment terminated on December 2, 2013, with the divestiture of New AER. Actual shares issued for retirement-eligible employees and former New AER subsidiaries' employees will vary depending on actual performance over the three-year measurement period.
Income Taxes (Tables)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Income Tax Disclosure [Abstract]
 
 
Schedule Of Effective Income Tax Rate Reconciliation
Text Block 
 
Schedule Of Components Of Income Tax Expense (Benefit)
Text Block 
 
Schedule Of Deferred Tax Assets And Liabilities Resulting From Temporary Differences
Text Block 
 
Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards
Text Block 
Text Block 
Schedule Of Changes To Unrecognized Tax Benefits And Related Interest
Text Block 
 
Reconciliation Of Changes In Liability For Interest On Unrecognized Tax Benefits
Text Block 
 
Schedule Of Effective Income Tax Rate Reconciliation 
The following table presents the principal reasons why the effective income tax rate differed from the statutory federal income tax rate for the years ended December 31, 2013, 2012, and 2011:
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2013
 
 
 
 
 
Statutory federal income tax rate:
35
 %
 
35
 %
 
35
 %
Increases (decreases) from:
 
 
 
 
 
Depreciation differences
—

 
(1
)
 
—

Amortization of investment tax credit
(1
)
 
—

 
(1
)
State tax
3

 
6

 
4

Other permanent items(a)
1

 
—

 
—

Effective income tax rate
38
 %
 
40
 %
 
38
 %
2012
 
 
 
 
 
Statutory federal income tax rate:
35
 %
 
35
 %
 
35
 %
Increases (decreases) from:
 
 
 
 
 
Depreciation differences
(1
)
 
—

 
(1
)
Amortization of investment tax credit
(1
)
 
(1
)
 
(1
)
State tax
3

 
6

 
5

Reserve for uncertain tax positions
1

 
—

 
—

Other permanent items(a)
—

 
—

 
(1
)
Effective income tax rate
37
 %
 
40
 %
 
37
 %
2011
 
 
 
 
 
Statutory federal income tax rate:
35
 %
 
35
 %
 
35
 %
Increases (decreases) from:
 
 
 
 
 
Depreciation differences
(2
)
 
—

 
(1
)
Amortization of investment tax credit
(1
)
 
(1
)
 
(1
)
State tax
3

 
5

 
4

Reserve for uncertain tax positions
—

 
—

 
1

Tax credits
—

 
—

 
(1
)
Other permanent items(a)
1

 
—

 
—

Effective income tax rate
36
 %
 
39
 %
 
37
 %
(a)
Permanent items are treated differently for book and tax purposes and primarily include non-taxable income related to company-owned life insurance and deductions related to dividends on DRPlus and the 401(k) plan for Ameren, as well as nondeductible expenses related to lobbying and stock issuance costs for Ameren Missouri.
Schedule Of Components Of Income Tax Expense (Benefit) 
The following table presents the components of income tax expense (benefit) for the years ended December 31, 2013, 2012, and 2011:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
2013
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
136

 
$
(15
)
 
$
(239
)
(b) 
$
(118
)
State
41

 
21

 
(43
)
(b) 
19

Deferred taxes:
 
 
 
 
 
 
 
Federal
64

 
99

 
205

(b) 
368

State
6

 
6

 
36

(b) 
48

Deferred investment tax credits, amortization
(5
)
 
(1
)
 
—

 
(6
)
Total income tax expense (benefit)
$
242

 
$
110

 
$
(41
)
 
$
311

2012
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
(25
)
 
$
(7
)
 
$
72

 
$
40

State
(10
)
 
(3
)
 
23

 
10

Deferred taxes:
 
 
 
 
 
 
 
Federal
248

 
76

 
(120
)
 
204

State
44

 
30

 
(14
)
 
60

Deferred investment tax credits, amortization
(5
)
 
(2
)
 
—

 
(7
)
Total income tax expense (benefit)
$
252

 
$
94

 
$
(39
)
 
$
307

2011
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
3

 
$
(24
)
 
$
15

 
$
(6
)
State
2

 
(4
)
 
—

 
(2
)
Deferred taxes:
 
 
 
 
 
 
 
Federal
129

 
123

 
(39
)
 
213

State
31

 
34

 
(10
)
 
55

Deferred investment tax credits, amortization
(4
)
 
(2
)
 
—

 
(6
)
Total income tax expense (benefit)
$
161

 
$
127

 
$
(34
)
 
$
254

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
These amounts are substantially related to the reversal of unrecognized tax benefits as a result of new IRS guidance related to the deductibility of expenditures to maintain, replace or improve steam or electric power generation property, along with casualty loss deductions for storm damage. They also reflect the increase in deferred tax expense due to available net operating losses.
Schedule Of Deferred Tax Assets And Liabilities Resulting From Temporary Differences 
The following table presents the deferred tax assets and deferred tax liabilities recorded as a result of temporary differences at December 31, 2013, and 2012:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
2013
 
 
 
 
 
 
 
Accumulated deferred income taxes, net liability (asset):
 
 
 
 
 
 
 
Plant related
$
2,513

 
$
1,243

 
$
13

 
$
3,769

Regulatory assets, net
74

 
2

 
—

 
76

Deferred employee benefit costs
(74
)
 
(85
)
 
(114
)
 
(273
)
Purchase accounting
—

 
(27
)
 
(1
)
 
(28
)
ARO
(7
)
 
1

 
—

 
(6
)
Other(b)(c)
(17
)
 
(63
)
 
(398
)
 
(478
)
Total net accumulated deferred income tax liabilities (assets)(d)
$
2,489

 
$
1,071

 
$
(500
)
 
$
3,060

2012
 
 
 
 
 
 
 
Accumulated deferred income taxes, net liability (asset):
 
 
 
 
 
 
 
Plant related
$
2,385

 
$
1,145

 
$
20

 
$
3,550

Regulatory assets, net
73

 
—

 
—

 
73

Deferred employee benefit costs
(84
)
 
(102
)
 
(137
)
 
(323
)
Purchase accounting
—

 
(27
)
 
(1
)
 
(28
)
ARO
(7
)
 
1

 
—

 
(6
)
Other(b)
50

 
(77
)
 
(223
)
 
(250
)
Total net accumulated deferred income tax liabilities (assets)(e)
$
2,417

 
$
940

 
$
(341
)
 
$
3,016

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
Includes deferred tax assets related to net operating loss and tax credit carryforwards detailed in the table below.
(c)
Includes total valuation allowances for Ameren, Ameren Missouri, and Ameren Illinois of $7 million, $1 million, and $1 million, respectively, as of December 31, 2013. The state valuation allowances are shown in the table below.
(d)
Includes $20 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2013.
(e)
Includes $26 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2012.
Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards 
The following table presents the components of deferred tax assets relating to net operating loss carryforwards and tax credit carryforwards at December 31, 2013:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
Net operating loss carryforwards:
 
 
 
 
 
 
 
Federal(b)
$
61

 
$
84

 
$
215

 
$
360

State(c)
3

 
11

 
34

 
48

Total net operating loss carryforwards
$
64

 
$
95

 
$
249

 
$
408

Tax credit carryforwards:
 
 
 
 
 
 
 
Federal(d)
$
12

 
$
—

 
$
76

 
$
88

State(e)
1

 
1

 
32

 
34

State valuation allowance(f)
(1
)
 
(1
)
 
(2
)
 
(4
)
Total tax credit carryforwards
$
12

 
$
—

 
$
106

 
$
118

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
These will begin to expire in 2028.
(c)
These will begin to expire in 2017.
(d)
These will begin to expire in 2029.
(e)
These will begin to expire in 2014.
(f)
This balance increased by $2 million, $- million and $- million for Ameren, Ameren Missouri and Ameren Illinois, respectively, during 2013.
Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards 
The following table presents the components of deferred tax assets relating to net operating loss carryforwards and tax credit carryforwards at December 31, 2012:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
Net operating loss carryforwards:
 
 
 
 
 
 
 
Federal(b)
$
61

 
$
61

 
$
51

 
$
173

State(c)
3

 
11

 
13

 
27

Total net operating loss carryforwards
$
64

 
$
72

 
$
64

 
$
200

Tax credit carryforwards:
 
 
 
 
 
 
 
Federal(d)
$
11

 
$
—

 
$
75

 
$
86

State(e)
1

 
1

 
23

 
25

State valuation allowance(f)
(1
)
 
(1
)
 
—

 
(2
)
Total tax credit carryforwards
$
11

 
$
—

 
$
98

 
$
109

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
These will begin to expire in 2028
(c)
These will begin to expire in2017.
(d)
These will begin to expire in 2029.
(e)
These began to expire in 2013.
(f)
This balance increased by $1 million, $- million and $1 million for Ameren, Ameren Missouri and Ameren Illinois, respectively, during 2012.
Schedule Of Changes To Unrecognized Tax Benefits And Related Interest 
A reconciliation of the change in the unrecognized tax benefit balance during the years ended December 31, 2011, 2012, and 2013, is as follows:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
Unrecognized tax benefits – January 1, 2011
$
164

 
$
56

 
$
26

 
$
246

Increases based on tax positions prior to 2011
15

 
—

 
7

 
22

Decreases based on tax positions prior to 2011
(63
)
 
(41
)
 
(21
)
 
(125
)
Increases based on tax positions related to 2011
13

 
—

 
4

 
17

Changes related to settlements with taxing authorities
(5
)
 
(4
)
 
(1
)
 
(10
)
Decreases related to the lapse of statute of limitations
—

 
—

 
(2
)
 
(2
)
Unrecognized tax benefits – December 31, 2011
$
124

 
$
11

 
$
13

 
$
148

Increases based on tax positions prior to 2012
4

 
—

 
1

 
5

Decreases based on tax positions prior to 2012
(7
)
 
(1
)
 
(5
)
 
(13
)
Increases (decreases) based on tax positions related to 2012
15

 
3

 
(1
)
 
17

Changes related to settlements with taxing authorities
—

 
—

 
—

 
—

Decreases related to the lapse of statute of limitations
—

 
—

 
(1
)
 
(1
)
Unrecognized tax benefits – December 31, 2012
$
136

 
$
13

 
$
7

 
$
156

Increases based on tax positions prior to 2013
—

 
2

 
5

 
7

Decreases based on tax positions prior to 2013
(122
)
 
(16
)
 
(5
)
 
(143
)
Increases based on tax positions related to 2013
16

 
—

 
53

(b) 
69

Changes related to settlements with taxing authorities
—

 
—

 
—

 
—

Increases related to the lapse of statute of limitations
1

 
—

 
—

 
1

Unrecognized tax benefits (detriments) – December 31, 2013
$
31

 
$
(1
)
 
$
60

 
$
90

Total unrecognized tax benefits that, if recognized, would affect the effective tax rates as of December 31, 2011
$
1

 
$
—

 
$
—

 
$
1

Total unrecognized tax benefits (detriments) that, if recognized, would affect the effective tax rates as of December 31, 2012
$
3

 
$
(1
)
 
$
(1
)
 
$
1

Total unrecognized tax benefits that, if recognized, would affect the effective tax rates as of December 31, 2013
$
3

 
$
—

 
$
51

(b) 
$
54

Reconciliation Of Changes In Liability For Interest On Unrecognized Tax Benefits 
A reconciliation of the change in the liability for interest on unrecognized tax benefits during the years ended December 31, 2011, 2012, and 2013, is as follows:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren(a)
Liability for interest – January 1, 2011
$
10

 
$
2

 
$
5

 
$
17

Interest income for 2011
(3
)
 
(1
)
 
(7
)
 
(11
)
Interest payment
(1
)
 
—

 
—

 
(1
)
Liability for interest – December 31, 2011
$
6

 
$
1

 
$
(2
)
 
$
5

Interest charges (income) for 2012
2

 
—

 
(1
)
 
1

Liability for interest – December 31, 2012
$
8

 
$
1

 
$
(3
)
 
$
6

Interest charges (income) for 2013
(8
)
 
(1
)
 
4

 
(5
)
Liability for interest – December 31, 2013
$
—

 
$
—

 
$
1

 
$
1

Related Party Transactions (Tables)
Schedule of Related Party Transactions
The following table presents the impact on Ameren Missouri and Ameren Illinois of related party transactions for the years ended December 31, 2013, 2012, and 2011. It is based primarily on the agreements discussed above and the money pool arrangements discussed in Note 4 – Short-term Debt and Liquidity.
Agreement
Income Statement Line Item                    
 
  
 
Ameren
Missouri
 
Ameren
Illinois
Ameren Missouri power supply agreements
Operating Revenues
 
2013
$
3

$
(a)

with Ameren Illinois
 
 
2012
 
(b)

 
(a)

 
 
 
2011
 
2

 
(a)

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2013
 
21

 
1

rent and facility services
 
 
2012
 
19

 
1

 
 
 
2011
 
16

 
2

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2013
 
1

 
3

miscellaneous support services
 
 
2012
 
1

 
(b)

 
 
 
2011
 
5

 
1

Total Operating Revenues
 
 
2013
$
25

$
4

 
 
 
2012
 
20

 
1

 
 
 
2011
 
23

 
3

Ameren Illinois power supply
Purchased Power
 
2013
$
(a)

$
3

agreements with Ameren Missouri
 
 
2012
 
(a)

 
(b)

 
 
 
2011
 
(a)

 
2

Ameren Illinois transmission
Purchased Power
 
2013
 
(a)

 
2

services with ATXI
 
 
2012
 
(a)

 
3

 
 
 
2011
 
(a)

 
3

Total Purchased Power
 
 
2013
$
(a)

$
5

 
 
 
2012
 
(a)

 
3

 
 
 
2011
 
(a)

 
5

Ameren Services support services
Other Operations and
 
2013
$
116

$
93

agreement
Maintenance
 
2012
 
106

 
88

 
 
 
2011
 
114

 
87

Insurance premiums(c)
Other Operations and
 
2013
 
(b)

 
(a)

 
Maintenance
 
2012
 
(b)

 
(a)

 
 
 
2011
 
(b)

 
(a)

Total Other Operations and
 
 
2013
$
116

$
93

Maintenance Expenses
 
 
2012
 
106

 
88

 
 
 
2011
 
114

 
87

Money pool borrowings (advances)
Interest (Charges)
 
2013
$
(b)

$
(b)

 
Income
 
2012
 
(b)

 
(b)

 
 
 
2011
 
—

 
—

(a)
Not applicable.
(b)
Amount less than $1 million.
(c)
Represents insurance premiums paid to Energy Risk Assurance Company, an affiliate for replacement power, property damage, and terrorism coverage.
Commitments And Contingencies (Tables)
Schedule Of Insurance Coverage At Callaway Energy Center 
The following table presents insurance coverage at Ameren Missouri’s Callaway energy center at December 31, 2013. The property coverage and the nuclear liability coverage must be renewed on April 1 and January 1, respectively, of each year.
Type and Source of Coverage
Maximum Coverages
 
Maximum Assessments
 
Public liability and nuclear worker liability:
 
 
 
 
American Nuclear Insurers
$
375


$
—

 
Pool participation
13,241

(a)  
128

(b)  
 
$
13,616

(c)  
$
128

 
Property damage:
 
 
 
 
Nuclear Electric Insurance Limited
$
2,250

(d)  
$
23

(e)  
European Mutual Association for Nuclear Insurance
500

(f)  
—

 
 
$
2,750

 
$
23

 
Replacement power:
 
 
 
 
Nuclear Electric Insurance Limited
$
490

(g)  
$
9

(e)  
Missouri Energy Risk Assurance Company
$
64

(h)  
$
—

 

(a)
Provided through mandatory participation in an industrywide retrospective premium assessment program.
(b)
Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $375 million in the event of an incident at any licensed United States commercial reactor, payable at $19 million per year.
(c)
Limit of liability for each incident under the Price-Anderson Act liability provisions of the Atomic Energy Act of 1954, as amended. A company could be assessed up to $128 million per incident for each licensed reactor it operates with a maximum of $19 million per incident to be paid in a calendar year for each reactor. This limit is subject to change to account for the effects of inflation and changes in the number of licensed reactors.
(d)
Nuclear Electric Insurance Limited provides $2.25 billion in property damage, decontamination, and premature decommissioning insurance. There is a $1.7 billion sublimit for non-radiation events, of which the top $200 million is a shared limit with other generators purchasing this coverage and includes one free reinstatement.
(e)
All Nuclear Electric Insurance Limited insured plants could be subject to assessments should losses exceed the accumulated funds from Nuclear Electric Insurance Limited.
(f)
European Mutual Association for Nuclear Insurance provides $500 million in excess of the $2.25 billion property coverage and $1.7 billion non-radiation coverage.
(g)
Provides replacement power cost insurance in the event of a prolonged accidental outage at our nuclear energy center. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first eight weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter for a total not exceeding the policy limit of $490 million. Effective April 1, 2013, non-radiation events are sub-limited to $327.6 million.
(h)
Provides replacement power cost insurance in the event of a prolonged accidental outage at our nuclear energy center. The coverage commences after the first 52 weeks of insurance coverage from Nuclear Electric Insurance Limited and is a weekly indemnity of $900,000 for 71 weeks in excess of the $3.6 million per week set forth above. Missouri Energy Risk Assurance Company LLC is an affiliate and has reinsured this coverage with third-party insurance companies. See Note 14 – Related Party Transactions for more information on this affiliate transaction.
Schedule Of Lease Obligations 
We lease various facilities, office equipment, plant equipment, and rail cars under capital and operating leases. The following table presents our lease obligations at December 31, 2013:
 
Total
 
2014
 
2015
 
2016
 
2017
 
2018
 
After 5 Years
Ameren:(a)
 
 
 
 
 
 
 
 
 
 
 
 
 
Minimum capital lease payments(b)
$
556

 
$
32

 
$
33

 
$
33

 
$
33

 
$
32

 
$
393

Less amount representing interest
257

 
27

 
27

 
27

 
27

 
26

 
123

Present value of minimum capital lease payments
$
299

 
$
5

 
$
6

 
$
6

 
$
6

 
$
6

 
$
270

Operating leases(c)
117

 
14

 
13

 
13

 
13

 
13

 
51

Total lease obligations
$
416

 
$
19

 
$
19

 
$
19

 
$
19

 
$
19

 
$
321

Ameren Missouri:
 
 
 
 
 
 
 
 
 
 
 
 
 
Minimum capital lease payments(b)
$
556

 
$
32

 
$
33

 
$
33

 
$
33

 
$
32

 
$
393

Less amount representing interest
257

 
27

 
27

 
27

 
27

 
26

 
123

Present value of minimum capital lease payments
$
299

 
$
5

 
$
6

 
$
6

 
$
6

 
$
6

 
$
270

Operating leases(c)
106

 
11

 
11

 
11

 
12

 
11

 
50

Total lease obligations
$
405

 
$
16

 
$
17

 
$
17

 
$
18

 
$
17

 
$
320

Ameren Illinois:
 
 
 
 
 
 
 
 
 
 
 
 
 
Operating leases(c)
$
7

 
$
2

 
$
1

 
$
1

 
$
1

 
$
1

 
$
1

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
See Properties under Part I, Item 2, and Note 3 – Property and Plant, Net, of this report for additional information.
(c)
Amounts related to certain land-related leases have indefinite payment periods. The annual obligation of $2 million, $1 million and $1 million for Ameren, Ameren Missouri and Ameren Illinois for these items is included in the 2014 through 2018 columns, respectively.
Schedule Of Rental Expense 
The following table presents total rental expense, included in operating expenses, for the years ended December 31, 2013, 2012, and 2011:
 
2013
 
2012
 
2011
Ameren(a)
$
32

 
$
33

 
$
36

Ameren Missouri
29

 
29

 
29

Ameren Illinois
21

 
19

 
17

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
Schedule Of Estimated Purchased Commitments 
The table below presents our estimated commitments at December 31, 2013. Ameren’s and Ameren Missouri’s purchased power obligations include a 102-megawatt power purchase agreement with a wind farm operator that expires in 2024. Ameren’s and Ameren Illinois’ purchased power obligations include the Ameren Illinois power purchase agreements entered into as part of the IPA-administered power procurement process. Included in the Other column are minimum purchase commitments under contracts for equipment, design and construction, and meter reading services at December 31, 2013. Ameren's and Ameren Illinois' Other column also include obligations related to IEIMA. In addition, the Other column includes Ameren's and Ameren Missouri's obligations related to energy efficiency programs under the MEEIA as approved by the MoPSC's December 2012 electric rate order. Ameren Missouri expects to incur $48 million in 2014 and $64 million in 2015 for these energy efficiency programs. See Note 2 – Rate and Regulatory Matters for additional information about the IEIMA and MEEIA.
 
Coal
 
Natural
Gas(a)
 
Nuclear
Fuel
 
Purchased
Power(b)
 
Methane
Gas
 
Other
 
Total
Ameren:(c)
 
 
 
 
 
 
 
 
 
 
 
 
 
2014
$
620

 
$
323

 
$
64

 
$
308

 
$
3

 
$
201

 
$
1,519

2015
642

 
179

 
63

 
164

 
4

 
143

 
1,195

2016
664

 
90

 
81

 
78

 
4

 
76

 
993

2017
676

 
45

 
58

 
55

 
4

 
50

 
888

2018
120

 
28

 
57

 
52

 
5

 
51

 
313

Thereafter
125

 
82

 
158

 
635

 
91

 
350

 
1,441

Total
$
2,847

 
$
747

 
$
481

 
$
1,292

 
$
111

 
$
871

 
$
6,349

Ameren Missouri:
 
 
 
 
 
 
 
 
 
 
 
 
 
2014
$
620

 
$
62

 
$
64

 
$
19

 
$
3

 
$
127

 
$
895

2015
642

 
32

 
63

 
19

 
4

 
101

 
861

2016
664

 
19

 
81

 
19

 
4

 
40

 
827

2017
676

 
11

 
58

 
19

 
4

 
26

 
794

2018
120

 
8

 
57

 
19

 
5

 
27

 
236

Thereafter
125

 
28

 
158

 
110

 
91

 
183

 
695

Total
$
2,847

 
$
160

 
$
481

 
$
205

 
$
111

 
$
504

 
$
4,308

Ameren Illinois:
 
 
 
 
 
 
 
 
 
 
 
 
 
2014
$
—

 
$
261

 
$
—

 
$
289

 
$
—

 
$
23

 
$
573

2015
—

 
147

 
—

 
145

 
—

 
24

 
316

2016
—

 
71

 
—

 
59

 
—

 
24

 
154

2017
—

 
34

 
—

 
36

 
—

 
24

 
94

2018
—

 
20

 
—

 
33

 
—

 
24

 
77

Thereafter
—

 
54

 
—

 
525

 
—

 
167

 
746

Total
$
—

 
$
587

 
$
—

 
$
1,087

 
$
—

 
$
286

 
$
1,960

(a)
Includes amounts for generation and for distribution.
(b)
The purchased power amounts for Ameren and Ameren Illinois include 20-year agreements for renewable energy credits that were entered into in December 2010 with various renewable energy suppliers. The agreements contain a provision that allows Ameren Illinois to reduce the quantity purchased in the event that Ameren Illinois would not be able to recover the costs associated with the renewable energy credits.
(c)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
Schedule Of Estimated Obligations For Manufactured Gas Plant Remediation 
The following table presents, as of December 31, 2013, the estimated obligation to complete the remediation of these former MGP sites.
  
Estimate
 
Recorded
Liability(a)
  
Low
 
High
 
Ameren
$
278

 
$
338

 
$
278

Ameren Missouri
4

 
5

 
4

Ameren Illinois
274

 
333

 
274

(a)
Recorded liability represents the estimated minimum probable obligations, as no other amount within the range provided a better estimate.
Schedule Of Asbestos-Related Litigation Pending Lawsuits 
The following table presents the pending asbestos-related lawsuits filed against the Ameren Companies as of December 31, 2013:
Ameren
 
Ameren
Missouri
 
Ameren
Illinois
 
Total(a)
1
 
47
 
50
 
71

(a)
Total does not equal the sum of the subsidiary unit lawsuits because some of the lawsuits name multiple Ameren entities as defendants.
Divestiture Transactions and Discontinued Operations (Tables)
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures
The following table presents the components of discontinued operations in Ameren's consolidated statement of income (loss) for the years ended December 31, 2013, 2012 and 2011:
 
Year ended
 
2013
 
2012
 
2011
Operating revenues
$
1,037

 
$
1,047

 
$
1,358

Operating expenses
(1,207
)
(a) 
(3,474
)
(b) 
(1,150
)
Operating income (loss)
(170
)
 
(2,427
)
 
208

Other income (loss)
(1
)
 
—

 
1

Interest charges
(39
)
 
(56
)
 
(64
)
Income (loss) before income taxes
(210
)
 
(2,483
)
 
145

Income tax (expense) benefit
(13
)
 
987

 
(56
)
Income (loss) from discontinued operations, net of taxes
$
(223
)
 
$
(1,496
)
 
$
89

(a)
Includes a $201 million pretax loss on disposal relating to the New AER divestiture.
(b)
Includes a noncash pretax asset impairment charge of $628 million to reduce the carrying value of AERG’s Duck Creek energy center to its estimated fair value under held and used accounting guidance. In addition, includes a noncash pretax asset impairment charge of $1.95 billion to reduce the carrying values of all the AER coal and natural gas-fired energy centers, except the Joppa coal-fired energy center, to their estimated fair values, under held and used accounting guidance, as a result of the decision in December 2012 that Ameren intended to exit the Merchant Generation business.
The following table presents the carrying amounts of the components of assets and liabilities segregated on Ameren's consolidated balance sheets as discontinued operations at December 31, 2013, and 2012:
 
December 31, 2013
 
December 31, 2012
Assets of discontinued operations
 
 
 
Cash and cash equivalents
$
—

 
$
25

Accounts receivable and unbilled revenue
5

 
102

Materials and supplies
5

 
135

Mark-to-market derivative assets
—

 
102

Property and plant, net
142

 
748

Accumulated deferred income taxes, net(a)
13

 
395

Other assets
—

 
104

Total assets of discontinued operations
$
165

 
$
1,611

Liabilities of discontinued operations
 
 
 
Accounts payable and other current obligations
$
5

 
$
141

Mark-to-market derivative liabilities
—

 
63

Long-term debt, net
—

 
824

Asset retirement obligations(b)
40

 
97

Pension and other postretirement benefits
—

 
40

Other liabilities
—

 
28

Total liabilities of discontinued operations
$
45

 
$
1,193

Accumulated other comprehensive income (c)
$
—

 
$
19

Noncontrolling interest(d)
$
—

 
$
8

(a)
The December 31, 2013 balance primarily consists of deferred income tax assets related to the abandoned Meredosia and Hutsonville energy centers.
(b)
Includes AROs associated with the abandoned Meredosia and Hutsonville energy centers of $31 million and $26 million at December 31, 2013, and 2012, respectively.
(c)
Accumulated other comprehensive income related to discontinued operations included in “Accumulated other comprehensive loss” on Ameren’s December 31, 2012, consolidated balance sheet. This balance related to New AER assets and liabilities that were realized or removed from Ameren’s consolidated balance sheet either before or at the December 2, 2013 closing of the New AER divestiture.
(d)
The 20% ownership interest of EEI not owned by Ameren was included in “Noncontrolling interests” on Ameren’s December 31, 2012, consolidated balance sheet. This noncontrolling interest was removed from Ameren’s consolidated balance sheet at the December 2, 2013 closing of the New AER divestiture.
Segment Information (Tables)
Schedule Of Segment Reporting Information, By Segment
The following table presents information about the reported revenues and specified items reflected in Ameren’s net income attributable to Ameren Corporation from continuing operations for the years ended December 31, 2013, 2012, and 2011, and total assets in continuing operations as of December 31, 2013, 2012, and 2011.
Ameren
 
Ameren
Missouri
 
Ameren
Illinois
 
Other
 
Intersegment
Eliminations
 
Consolidated
 
2013
 
 
 
 
 
 
 
 
 
 
External revenues
$
3,516

 
$
2,307

 
$
15

 
$
—

 
$
5,838

 
Intersegment revenues
25

 
4

 
2

 
(31
)
 
—

 
Depreciation and amortization
454

 
243

 
9

 
—

 
706

 
Interest and dividend income
27

 
2

 
1

 
—

 
30

 
Interest charges
210

 
143

 
45

 
—

 
398

 
Income taxes (benefit)
242

 
110

 
(41
)
 
—

 
311

 
Net income (loss) attributable to Ameren Corporation from continuing operations
395

 
160

 
(43
)
 
—

 
512

 
Capital expenditures
648

 
701

 
30

(a) 
—

 
1,379

 
Total assets
12,904

 
7,454

 
752

 
(233
)
 
20,877

(b) 
2012
 
 
 
 
 
 
 
 
 
 
External revenues
$
3,252

 
$
2,524

 
$
5

 
$
—

 
$
5,781

 
Intersegment revenues
20

 
1

 
3

 
(24
)
 
—

 
Depreciation and amortization
440

 
221

 
12

 
—

 
673

 
Interest and dividend income
32

 
—

 
—

 
—

 
32

 
Interest charges
223

 
129

 
40

 
—

 
392

 
Income taxes (benefit)
252

 
94

 
(39
)
 
—

 
307

 
Net income (loss) attributable to Ameren Corporation from continuing operations
416

 
141

 
(41
)
 
—

 
516

 
Capital expenditures
595

 
442

 
26

(a) 
—

 
1,063

 
Total assets
13,043

 
7,282

 
1,228

 
(934
)
 
20,619

(b) 
2011
 
 
 
 
 
 
 
 
 
 
External revenues
$
3,360

 
$
2,784

 
$
4

 
$
—

 
$
6,148

 
Intersegment revenues
23

 
3

 
3

 
(29
)
 
—

 
Depreciation and amortization
408

 
215

 
20

 
—

 
643

 
Interest and dividend income
30

 
1

 
—

 
—

 
31

 
Interest charges
209

 
136

 
42

 
—

 
387

 
Income taxes (benefit)
161

 
127

 
(34
)
 
—

 
254

 
Net income (loss) attributable to Ameren Corporation from continuing operations
287

 
193

 
(49
)
 
—

 
431

 
Capital expenditures
550

 
351

 
(20
)
(a) 
—

 
881

 
Total assets
12,757

 
7,213

 
1,211

 
(1,179
)
 
20,002

(b) 
.
(a)
Includes the elimination of intercompany transfers.
Selected Quarterly Information (Tables)
Summary Of Selected Quarterly Information
SELECTED QUARTERLY INFORMATION (Unaudited) (In millions, except per share amounts)
Ameren
2013
 
 
2012
Quarter ended (a)
March 31
 
June 30
 
September 30
 
December 31
 
 
March 31
 
June 30
 
September 30
 
December 31
Operating revenues
$
1,475

 
$
1,403

 
$
1,638

 
$
1,322

 
 
$
1,412

 
$
1,402

 
$
1,709

 
$
1,258

Operating income
185

 
261

 
567

 
171

 
 
159

 
347

 
570

 
112

Net income (loss)(b)
(143
)
 
96

 
304

 
38

 
 
(403
)
 
210

 
374

 
(1,155
)
Net income attributable to Ameren Corporation – continuing operations
$
54

 
$
105

 
$
305

 
$
48

 
 
$
38

 
$
164

 
$
302

 
$
12

Net income (loss) attributable to Ameren Corporation – discontinued operations (b)
(199
)
 
(10
)
 
(3
)
 
(11
)
 
 
(441
)
 
47

 
72

 
(1,168
)
Net income (loss) attributable to Ameren Corporation
$
(145
)
 
$
95

 
$
302

 
$
37

 
 
$
(403
)
 
$
211

 
$
374

 
$
(1,156
)
Earnings per common share – basic – continuing operations
$
0.22

 
$
0.44

 
$
1.26

 
$
0.19

 
 
$
0.16

 
$
0.67

 
$
1.25

 
$
0.05

Earnings (loss) per common share – basic – discontinued operations
(0.82
)
 
(0.05
)
 
(0.01
)
 
(0.04
)
 
 
(1.82
)
 
0.20

 
0.29

 
(4.81
)
Earnings (loss) per common share – basic
$
(0.60
)
 
$
0.39

 
$
1.25

 
$
0.15

 
 
$
(1.66
)
 
$
0.87

 
$
1.54

 
$
(4.76
)
Earnings per common share – diluted – continuing operations
$
0.22

 
$
0.44

 
$
1.25

 
$
0.19

 
 
$
0.16

 
$
0.67

 
$
1.25

 
$
0.05

Earnings (loss) per common share – diluted – discontinued operations
(0.82
)
 
(0.05
)
 
(0.01
)
 
(0.04
)
 
 
(1.82
)
 
0.20

 
0.29

 
(4.81
)
Earnings (loss) per common share – diluted
$
(0.60
)
 
$
0.39

 
$
1.24

 
$
0.15

 
 
$
(1.66
)
 
$
0.87

 
$
1.54

 
$
(4.76
)
(a)
The sum of quarterly amounts, including per share amounts, may not equal amounts reported for year-to-date periods. This is due to the effects of rounding and to changes in the number of weighted-average shares outstanding each period.
(b)
Includes pretax asset impairment charge of $2.6 billion recorded in discontinued operations during the year ended December 31, 2012. See Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, for additional information.
Ameren Missouri Quarter ended
 
Operating
revenues
 
Operating
income
 
Net income
(loss)
 
Net income (loss)
available
to common
stockholder
March 31, 2013
 
$
796

 
$
111

 
$
41

 
$
40

March 31, 2012
 
691

 
78

 
22

 
21

June 30, 2013
 
889

 
179

 
85

 
84

June 30, 2012
 
844

 
269

 
144

 
143

September 30, 2013
 
1,093

 
417

 
239

 
238

September 30, 2012
 
1,064

 
429

 
237

 
236

December 31, 2013
 
763

 
96

 
33

 
33

December 31, 2012
 
673

 
69

 
16

 
16


Ameren Illinois Quarter ended
 
Operating
revenues
 
Operating
income
 
Net income
 
Net income
available
to common
stockholder
March 31, 2013
 
$
684

 
$
85

 
$
32

 
$
31

March 31, 2012
 
724

 
89

 
28

 
27

June 30, 2013
 
516

 
87

 
32

 
31

June 30, 2012
 
564

 
86

 
33

 
32

September 30, 2013
 
547

 
158

 
77

 
77

September 30, 2012
 
648

 
151

 
71

 
71

December 31, 2013
 
564

 
85

 
22

 
21

December 31, 2012
 
589

 
51

 
12

 
11

Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Mar. 31, 2014
Dec. 31, 2010
Accounting Policies [Line Items]
 
 
 
 
 
Unrecognized Tax Benefits
$ 90 1
$ 156 1
$ 148 1
$ 48 
$ 246 1
Goodwill
411 
411 
 
 
 
Public Utilities, Property, Plant and Equipment, Amount of Indirect Disallowance of Costs of Recently Completed Plants
   
   
89 
 
 
Tax grants received related to renewable energy properties
   
18 
   
 
 
Book value
22 
14 
 
 
 
Ameren Illinois Company
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Unrecognized Tax Benefits
(1)
13 
11 
 
56 
Goodwill
411 
411 
 
 
 
Public Utilities, Area Serviced
40,000 
 
 
 
 
Public Utilities, Estimated Population of Service Territory
3,100,000 
 
 
 
 
Union Electric Company
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Unrecognized Tax Benefits
31 
136 
124 
15 
164 
Public Utilities, Property, Plant and Equipment, Amount of Indirect Disallowance of Costs of Recently Completed Plants
   
   
89 
 
 
Tax grants received related to renewable energy properties
   
18 
   
 
 
Public Utilities, Area Serviced
24,000 
 
 
 
 
Public Utilities, Estimated Population of Service Territory
2,800,000 
 
 
 
 
Book value
22 
14 
 
 
 
Electric Energy Inc
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Percentage of EEI not owned by Ameren
 
20.00% 
 
 
 
Voluntary Separation Offer
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Number Of Employee Positions Eliminated
 
 
340 
 
 
Severance Costs
 
 
28 
 
 
Voluntary Separation Offer |
Union Electric Company
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Severance Costs
 
 
27 
 
 
Minimum
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Percent of average depreciable cost
3.00% 
3.00% 
3.00% 
 
 
Maximum
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Percent of average depreciable cost
4.00% 
4.00% 
4.00% 
 
 
Power |
Ameren Illinois Company
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Public Utilities, Number of Customers
1,200,000 
 
 
 
 
Power |
Union Electric Company
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Public Utilities, Number of Customers
1,200,000 
 
 
 
 
Natural Gas |
Ameren Illinois Company
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Public Utilities, Number of Customers
767,000 
 
 
 
 
Natural Gas |
Union Electric Company
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Public Utilities, Number of Customers
127,000 
 
 
 
 
FAC |
Union Electric Company
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Sharing Level For Fac
95.00% 
 
 
 
 
Taum Sauk Energy Center |
Union Electric Company
 
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
 
Public Utilities, Property, Plant and Equipment, Amount of Indirect Disallowance of Costs of Recently Completed Plants
 
 
$ 89 
 
 
Summary Of Significant Accounting Policies (Schedule Of Material And Supplies) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Accounting Policies [Line Items]
 
 
Fuel
$ 144 1
$ 198 1
Gas stored underground
127 
131 
Other materials and supplies
255 
241 
Total materials and supplies
526 
570 
Union Electric Company
 
 
Accounting Policies [Line Items]
 
 
Fuel
144 1
198 1
Gas stored underground
17 
18 
Other materials and supplies
191 
181 
Total materials and supplies
352 
397 
Ameren Illinois Company
 
 
Accounting Policies [Line Items]
 
 
Fuel
   1
   1
Gas stored underground
110 
113 
Other materials and supplies
64 
60 
Total materials and supplies
$ 174 
$ 173 
Summary Of Significant Accounting Policies (Schedule Of Rates Used For Allowance For Funds Used During Construction) (Details)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Union Electric Company
 
 
 
Accounting Policies [Line Items]
 
 
 
Allowance for funds used during construction, rate
8.00% 
8.00% 
8.00% 
Ameren Illinois Company
 
 
 
Accounting Policies [Line Items]
 
 
 
Allowance for funds used during construction, rate
8.00% 
9.00% 
9.00% 
Summary Of Significant Accounting Policies (Schedule Of Amortization Expense) (Details) (Emission Allowances, USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
 
 
 
Amortization expense
$ 13 
$ 4 
$ 3 
Union Electric Company
 
 
 
Finite-Lived Intangible Assets [Line Items]
 
 
 
Amortization expense
1 1
1 1
1 1
Ameren Illinois Company
 
 
 
Finite-Lived Intangible Assets [Line Items]
 
 
 
Amortization expense
$ 13 
$ 4 
$ 3 
Summary Of Significant Accounting Policies (Schedule Of Excise Taxes) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Accounting Policies [Line Items]
 
 
 
Excise tax expense
$ 213 
$ 193 
$ 194 
Union Electric Company
 
 
 
Accounting Policies [Line Items]
 
 
 
Excise tax expense
152 
139 
137 
Ameren Illinois Company
 
 
 
Accounting Policies [Line Items]
 
 
 
Excise tax expense
$ 61 
$ 54 
$ 57 
Summary Of Significant Accounting Policies (Basic and Diluted Earnings Per Share Calculations) (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Accounting Policies [Abstract]
 
 
 
 
 
 
 
 
 
 
 
Continuing Operations
$ 48 
$ 305 
$ 105 
$ 54 
$ 12 
$ 302 
$ 164 
$ 38 
$ 512 
$ 516 
$ 431 
Discontinued Operations
11 
3 
10 
199 
1,168 
(72)
(47)
441 
(223)
(1,490)
88 
Net income (loss) attributable to Ameren Corporation
$ 37 
$ 302 
$ 95 
$ (145)
$ (1,156)
$ 374 
$ 211 
$ (403)
$ 289 
$ (974)
$ 519 
Average Common Shares Outstanding - Basic
 
 
 
 
 
 
 
 
242.6 
242.6 
241.5 
Assumed Settlement of Performance Share Units
 
 
 
 
 
 
 
 
1.9 
0.4 
0.6 
Average Common Shares Outstanding - Diluted
 
 
 
 
 
 
 
 
244.5 
243.0 
242.1 
Continuing Operations - Basic
$ 0.19 
$ 1.26 
$ 0.44 
$ 0.22 
$ 0.05 
$ 1.25 
$ 0.67 
$ 0.16 
$ 2.11 
$ 2.13 
$ 1.79 
Discontinued Operations - Basic
$ (0.04)
$ (0.01)
$ (0.05)
$ (0.82)
$ (4.81)
$ 0.29 
$ 0.20 
$ (1.82)
$ (0.92)
$ (6.14)
$ 0.36 
Earnings (Loss) per Common Share – Basic
$ 0.15 
$ 1.25 
$ 0.39 
$ (0.60)
$ (4.76)
$ 1.54 
$ 0.87 
$ (1.66)
$ 1.19 
$ (4.01)
$ 2.15 
Continuing Operations - Diluted
$ 0.19 
$ 1.25 
$ 0.44 
$ 0.22 
$ 0.05 
$ 1.25 
$ 0.67 
$ 0.16 
$ 2.10 
$ 2.13 
$ 1.79 
Discontinued Operations - Diluted
$ (0.04)
$ (0.01)
$ (0.05)
$ (0.82)
$ (4.81)
$ 0.29 
$ 0.20 
$ (1.82)
$ (0.92)
$ (6.14)
$ 0.36 
Earnings (Loss) per Common Share – Diluted
$ 0.15 
$ 1.24 
$ 0.39 
$ (0.60)
$ (4.76)
$ 1.54 
$ 0.87 
$ (1.66)
$ 1.18 
$ (4.01)
$ 2.15 
Average performance share units excluded from calculation
 
 
 
 
 
 
 
 
0.1 1
0.7 1
0 1
Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Supplemental Cash Flow Information) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Supplemental Cash Flow Information [Line Items]
 
 
 
Interest Paid, Net
$ 393 
$ 433 
$ 453 
Income Taxes Paid, Net
8 
1 
(61)
Continuing Operations [Member]
 
 
 
Supplemental Cash Flow Information [Line Items]
 
 
 
Interest Paid, Capitalized
20 
17 
27 
Interest Paid, Net
362 
384 
393 
Income Taxes Paid, Net
116 
10 
(47)
Discontinued Operations [Member]
 
 
 
Supplemental Cash Flow Information [Line Items]
 
 
 
Interest Paid, Capitalized
17 
13 
3 
Interest Paid, Net
31 
49 
60 
Income Taxes Paid, Net
$ (108)
$ (9)
$ (14)
Summary Of Significant Accounting Policies (Schedule Of Asset Retirement Obligations) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
 
 
Balance
$ 349 1
$ 331 1
Liabilities incurred
0 1
   1
Liabilities settled
(1)1
(1)1
Accretion in period
19 1 2
18 1 2
Change in estimates
2 1 3
1 1 3
Balance
369 1
349 1
Nuclear decommissioning trust fund
494 
408 
Union Electric Company
 
 
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
 
 
Balance
346 1
328 1
Liabilities incurred
   1
   1
Liabilities settled
(1)1
(1)1
Accretion in period
19 1 2
18 1 2
Change in estimates
2 1 3
1 1 3
Balance
366 1
346 1
Nuclear decommissioning trust fund
494 
408 
Ameren Illinois Company
 
 
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
 
 
Balance
3 4
3 4
Liabilities incurred
   4
   4
Liabilities settled
1 4 5
1 4 5
Accretion in period
1 2 4 5
1 2 4 5
Change in estimates
1 4 5
1 4 5
Balance
$ 3 4
$ 3 4
Rate And Regulatory Matters (Narrative) (Details) (USD $)
1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 60 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 1 Months Ended
Nov. 30, 2012
design
Dec. 31, 2013
design
Dec. 31, 2012
Dec. 31, 2011
Jun. 30, 2008
FERC Relicensing
Taum Sauk Energy Center
Dec. 31, 2013
Union Electric Company
Dec. 31, 2012
Union Electric Company
Dec. 31, 2011
Union Electric Company
Dec. 31, 2013
Union Electric Company
New Nuclear Energy Center COL
Feb. 13, 2014
Union Electric Company
Electric Distribution
customer
Apr. 30, 2011
Union Electric Company
Fac Prudence Review
Dec. 31, 2012
Union Electric Company
Entergy Refund
Dec. 31, 2005
Union Electric Company
Pending Ferc Case [Member]
Power Purchase Agreement With Entergy Arkansas
Dec. 31, 2012
Union Electric Company
Final Rate Order
Electric Distribution
Dec. 31, 2012
Union Electric Company
Final Rate Order
MEEIA
Electric Distribution
Dec. 31, 2013
Union Electric Company
Accounting Authority Order Request
Electric Distribution
Dec. 31, 2013
Ameren Illinois Company
customer
Dec. 31, 2012
Ameren Illinois Company
Dec. 31, 2011
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Wholesale Distribution Rate Case
Dec. 31, 2012
Ameren Illinois Company
Wholesale Distribution Rate Case
Dec. 31, 2013
Ameren Illinois Company
Final Rate Order
Gas Distribution
Dec. 18, 2013
Ameren Illinois Company
Final Rate Order
Gas Distribution
Dec. 9, 2013
Ameren Illinois Company
Final Rate Order
Electric Distribution
Dec. 9, 2013
Ameren Illinois Company
Final Rate Order
IEIMA
Electric Distribution
Dec. 31, 2012
Ameren Illinois Company
Final Rate Order
IEIMA
Electric Distribution
Dec. 9, 2013
Ameren Illinois Company
IEMA Revenue Requirement Reconciliation
Electric Distribution
Dec. 31, 2013
Ameren Illinois Company
IEMA Revenue Requirement Reconciliation
IEIMA
Electric Distribution
Dec. 31, 2012
Ameren Illinois Company
IEMA Revenue Requirement Reconciliation
IEIMA
Electric Distribution
Dec. 31, 2013
ATXI
Potential Transmission Project Investments Through 2019
Dec. 31, 2013
Maximum
Union Electric Company
New Nuclear Energy Center COL
Dec. 31, 2013
Maximum
Ameren Illinois Company
Pending Ferc Case [Member]
Dec. 31, 2013
Minimum
Union Electric Company
New Nuclear Energy Center COL
Dec. 31, 2013
Pending Ferc Case [Member]
Ameren Illinois Company
customer
Dec. 31, 2013
Midwest Independent Transmission System Operator, Inc [Member]
Pending Ferc Case [Member]
Dec. 31, 2013
Fac Prudence Review
Union Electric Company
Subsequent Periods After September 30, 2009
Dec. 31, 2013
FERC Revenue Requirement Reconciliation
Dec. 31, 2012
FERC Revenue Requirement Reconciliation
Dec. 31, 2013
FERC Revenue Requirement Reconciliation
Union Electric Company
Dec. 31, 2012
FERC Revenue Requirement Reconciliation
Union Electric Company
Dec. 31, 2013
FERC Revenue Requirement Reconciliation
Ameren Illinois Company
Dec. 31, 2012
FERC Revenue Requirement Reconciliation
Ameren Illinois Company
Dec. 31, 2013
FERC Revenue Requirement Reconciliation
ATXI
Feb. 28, 2014
Customer [Domain]
Union Electric Company
Electric Distribution
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Refund to Customers Under FAC
 
 
 
 
 
 
 
 
 
 
$ 18,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Authorized increase in revenue from utility service
 
 
 
 
 
 
 
 
 
 
 
 
 
260,000,000 
 
 
 
 
 
 
 
 
32,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Loss Contingency, Settlement Agreement, Number of Wholesale Customers
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4 
 
 
 
 
 
 
 
 
 
 
Number of Wholesale Customers
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
9 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5 
 
 
 
 
 
 
 
 
 
 
Rate of return on common equity
 
 
 
 
 
 
 
 
 
 
 
 
 
9.80% 
 
 
 
 
 
 
 
9.10% 
 
 
 
 
 
 
 
 
 
 
 
 
12.38% 
 
 
 
 
 
 
 
 
 
Percent of capital structure composed of equity
 
 
 
 
 
 
 
 
 
 
 
 
 
52.30% 
 
 
 
 
 
 
 
51.70% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Rate base
 
 
 
 
 
 
 
 
 
 
 
 
 
6,800,000,000 
 
 
 
 
 
 
 
1,100,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Incentive Award if Energy Efficiency Goals Are Achieved
 
 
 
 
 
 
 
 
 
 
 
 
 
 
19,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Achieved Percentage of Energy Efficiency Earnings For Incentive Award
 
 
 
 
 
 
 
 
 
 
 
 
 
 
100.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Incentive Award if Energy Efficiency Goals Are Achieved, Period
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3 years 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Minimum Percentage of Energy Efficiency Goal Achievement For Company To Be Eligible For Incentive Award
 
 
 
 
 
 
 
 
 
 
 
 
 
 
70.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Number of Customers Filed Complaint Case
 
 
 
 
 
 
 
 
 
37 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Contested return on equity
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
9.80% 
Customer Requested Rate on Equity
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
9.40% 
Revenue Requirement
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
788,000,000 
765,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Authorized Decrease In Revenue From Utility Service
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
(45,000,000)
23,000,000 
 
(68,000,000)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Disallowed costs associated with debt redemption
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
15,000,000 
15,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Current regulatory liabilities
 
216,000,000 
100,000,000 
 
 
57,000,000 
18,000,000 
 
 
 
 
 
 
 
 
 
159,000,000 
82,000,000 
 
13,000,000 
8,000,000 
 
 
 
 
 
 
65,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Noncurrent regulatory liabilities
 
1,705,000,000 
1,589,000,000 
 
 
1,041,000,000 
917,000,000 
 
 
 
 
 
 
 
 
 
664,000,000 
672,000,000 
 
 
 
 
 
 
 
 
 
 
55,000,000 
 
 
 
 
 
 
 
10,000,000 1
0 1
0 1
0 1
10,000,000 1
0 1
 
 
Loss Contingency, Estimate of Possible Loss
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
15,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
Proceeds from Legal Settlements
 
 
 
 
 
 
 
 
 
 
 
31,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Purchased power
 
502,000,000 
780,000,000 
952,000,000 
 
127,000,000 
78,000,000 
104,000,000 
 
 
 
24,000,000 
25,000,000 
 
 
 
380,000,000 
705,000,000 
853,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Department of Energy, Investing Funding Support, Number of Small Modular Reactor Designs
 
2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Department of Energy, Investing Funding Support, Period
 
5 years 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Number Of Years COL is Valid For
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
40 years 
 
 
 
 
 
 
 
 
 
 
 
Department of Energy, Investing Funding Support, Number of Small Modular Reactor Designs Awarded
1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Other Nonoperating Income
 
69,000,000 2
70,000,000 2
68,000,000 2
 
58,000,000 
63,000,000 
61,000,000 
 
 
 
5,000,000 
 
 
 
 
10,000,000 
7,000,000 
7,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Reduction To Under-recovered Asset
 
 
 
 
 
 
 
 
 
 
 
2,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Customer Refund Liability, Current
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
26,000,000 
 
 
 
 
 
 
 
 
Interest Expense
 
398,000,000 
392,000,000 
387,000,000 
 
210,000,000 
223,000,000 
209,000,000 
 
 
1,000,000 
 
 
 
 
 
143,000,000 
129,000,000 
136,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1,000,000 
 
 
 
 
 
 
 
 
Noncurrent regulatory assets
 
1,240,000,000 
1,786,000,000 
 
 
534,000,000 
852,000,000 
 
 
 
 
 
 
 
 
36,000,000 
701,000,000 
934,000,000 
 
 
 
 
 
 
 
 
 
65,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5,000,000 
 
Capital investments
 
 
 
 
 
 
 
 
$ 69,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
$ 1,100,000,000 
$ 100,000,000 
 
$ 80,000,000 
 
 
 
 
 
 
 
 
 
 
 
Number of years for proposed relicensing application filed with FERC
 
 
 
 
40 years 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Rate And Regulatory Matters (Schedule Of Regulatory Assets And Liabilities) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
$ 156 
$ 247 
Noncurrent regulatory assets
1,240 
1,786 
Current regulatory liabilities
216 
100 
Noncurrent regulatory liabilities
1,705 
1,589 
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
118 
163 
Noncurrent regulatory assets
534 
852 
Current regulatory liabilities
57 
18 
Noncurrent regulatory liabilities
1,041 
917 
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
38 
84 
Noncurrent regulatory assets
701 
934 
Current regulatory liabilities
159 
82 
Noncurrent regulatory liabilities
664 
672 
Under-Recovered FAC
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
104 1 2
145 1 2
Under-Recovered FAC |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
104 1 2
145 1 2
Under-Recovered FAC |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
0 1 2
0 1 2
Under-Recovered Illinois Electric Power Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
1 3
0 3
Under-Recovered Illinois Electric Power Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
   3
   3
Under-Recovered Illinois Electric Power Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
1 3
0 3
Under-Recovered PGA
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
1 3
12 3
Under-Recovered PGA |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
0 3
5 3
Under-Recovered PGA |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
1 3
7 3
MTM Derivative Losses
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
50 4
90 4
Noncurrent regulatory assets
126 4
135 4
MTM Derivative Losses |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
14 4
13 4
Noncurrent regulatory assets
8 4
7 4
MTM Derivative Losses |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
36 4
77 4
Noncurrent regulatory assets
118 4
128 4
Pension And Postretirement Benefit Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
184 5
772 5
Pension And Postretirement Benefit Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
44 5
348 5
Pension And Postretirement Benefit Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
140 5
424 5
Income Taxes
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
237 6
235 6
Noncurrent regulatory liabilities
41 7
46 7
Income Taxes |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
230 6
231 6
Noncurrent regulatory liabilities
38 7
42 7
Income Taxes |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
7 6
4 6
Noncurrent regulatory liabilities
3 7
4 7
Asset Retirement Obligation
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
5 8
5 8
Noncurrent regulatory liabilities
146 8
80 8
Asset Retirement Obligation |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
   8
0 8
Noncurrent regulatory liabilities
146 8
80 8
Asset Retirement Obligation |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
5 8
5 8
Noncurrent regulatory liabilities
   8
0 8
Callaway Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
40 1 9
44 1 9
Callaway Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
40 1 9
44 1 9
Callaway Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
   1 9
   1 9
Unamortized Loss On Reacquired Debt
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
151 1 10
181 1 10
Unamortized Loss On Reacquired Debt |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
77 1 10
81 1 10
Unamortized Loss On Reacquired Debt |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
74 1 10
100 1 10
Recoverable Costs Contaminated Facilities
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
271 11
248 11
Recoverable Costs Contaminated Facilities |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
   11
0 11
Recoverable Costs Contaminated Facilities |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
271 11
248 11
Storm Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
8 12
9 12
Storm Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
5 12
9 12
Storm Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
3 12
0 12
Demand-Side Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
58 1 13
73 1 13
Demand-Side Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
58 1 13
73 1 13
Demand-Side Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
   1 13
0 1 13
Reserve For Workers' Compensation Liabilities
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
12 14
12 14
Reserve For Workers' Compensation Liabilities |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
6 14
6 14
Reserve For Workers' Compensation Liabilities |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
6 14
6 14
Bad Debt Rider
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
8 15
12 15
Bad Debt Rider |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
   15
   15
Bad Debt Rider |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
8 15
12 15
Credit Facilities Fees
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
5 16
6 16
Credit Facilities Fees |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
5 16
6 16
Credit Facilities Fees |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
   16
0 16
Common Stock Issuance Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
4 17
7 17
Common Stock Issuance Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
4 17
7 17
Common Stock Issuance Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
   17
0 17
Construction Accounting For Pollution Control Equipment
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
22 1 18
23 1 18
Construction Accounting For Pollution Control Equipment |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
22 1 18
23 1 18
Construction Accounting For Pollution Control Equipment |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
   1 18
0 1 18
Solar Rebates
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
27 1 19
5 1 19
Solar Rebates |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
27 1 19
5 1 19
Solar Rebates |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
0 1 20
0 1 19
IEMA Revenue Requirement Reconciliation
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
65 21
0 21
Current regulatory liabilities
65 21
0 21
Noncurrent regulatory liabilities
0 21
55 21
IEMA Revenue Requirement Reconciliation |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
0 21
0 21
Current regulatory liabilities
0 21
0 21
Noncurrent regulatory liabilities
0 21
0 21
IEMA Revenue Requirement Reconciliation |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
65 21
0 21
Current regulatory liabilities
65 21
0 21
Noncurrent regulatory liabilities
0 21
55 21
Other
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
25 20 22
31 20
Noncurrent regulatory liabilities
10 23
4 23
Other |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
8 20
12 20
Noncurrent regulatory liabilities
10 23
4 23
Other |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory assets
12 20
19 20
Noncurrent regulatory liabilities
0 23
0 23
Over-Recovered FAC
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
26 2
0 2
Over-Recovered FAC |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
26 2
0 2
Over-Recovered FAC |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
0 2
0 2
Over-Recovered Illinois Electric Power Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
51 3
58 3
Over-Recovered Illinois Electric Power Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
0 3
0 3
Over-Recovered Illinois Electric Power Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
51 3
58 3
Over-Recovered PGA
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
34 3
15 3
Over-Recovered PGA |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
5 3
0 3
Over-Recovered PGA |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
29 3
15 3
MTM Derivative Gains
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
27 4
19 4
Noncurrent regulatory liabilities
1 4
2 4
MTM Derivative Gains |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
26 4
18 4
Noncurrent regulatory liabilities
1 4
2 4
MTM Derivative Gains |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
1 4
1 4
Noncurrent regulatory liabilities
   4
   4
Wholesale Distribution Refund
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
13 24
8 24
Wholesale Distribution Refund |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
0 24
0 24
Wholesale Distribution Refund |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
13 24
8 24
Removal Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
1,438 25
1,347 25
Removal Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
828 25
766 25
Removal Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
610 25
581 25
Pension And Postretirement Benefit Costs Tracker
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
15 26
23 26
Pension And Postretirement Benefit Costs Tracker |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
15 26
23 26
Pension And Postretirement Benefit Costs Tracker |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
0 26
0 26
Energy Efficiency Rider
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
36 27
20 27
Energy Efficiency Rider |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
3 27
0 27
Energy Efficiency Rider |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
33 27
20 27
FERC Revenue Requirement Reconciliation
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
10 28
0 28
FERC Revenue Requirement Reconciliation |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
0 28
0 28
FERC Revenue Requirement Reconciliation |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Noncurrent regulatory liabilities
$ 10 28
$ 0 28
[20] The Ameren Illinois total includes Ameren Illinois Merger integration and optimization costs, which are amortized over four years, beginning in January 2012. The Ameren Illinois total also includes costs related to the 2013 natural gas delivery service rate case costs, which are being amortized over a two-year period that began in January 2014. The Ameren Illinois total also includes a portion of the unamortized debt fair value adjustment recorded upon Ameren's acquisition of IP. This portion is being amortized over the remaining life of the related debt. At Ameren Missouri, the balance primarily includes the cost of renewable energy credits to fulfill its renewable energy portfolio requirement. Costs incurred from January 2010 through July 2012 are being amortized over three years, beginning in January 2013.
[27] The Ameren Illinois balance relates its regulatory tracking mechanism to recover its electric and natural gas costs associated with developing, implementing, and evaluating customer energy efficiency and demand response programs. This over-recovery will be refunded to customers over the following 12 months after the plan year. The Ameren Missouri balance relates to its MEEIA program costs incurred and projected lost revenues compared to the amount previously collected from customers. Beginning in January 2014, a MEEIA rider allows Ameren Missouri to collect from or refund to customers any annual difference in the actual amounts incurred and the projected amounts collected from customers for the MEEIA program costs and its projected lost revenues. Under the MEEIA rider, collections from or refunds to customers occur one year after the program costs and projected lost revenues are incurred.
Property And Plant, Net (Schedule Of Property And Plant, Net) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
equipment
Dec. 31, 2012
agreement
equipment
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
$ 23,701 1 2
$ 22,796 1 2
Accumulated depreciation and amortization
8,644 1 2
8,346 1 2
Property and plant, before construction work in progress
15,057 1 2
14,450 1 2
Property, Plant and Equipment, Net
16,205 1 2
15,348 1 2
Number of combustion turbine electric generation equipment under capital lease agreements
2 
2 
Number of capital lease agreements
2 
2 
Capital lease agreements, gross asset value
228 
228 
Total accumulated depreciation, capital lease agreements
56 
52 
Held-to-maturity Securities
299 
304 
Electric
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
21,726 1 2
20,942 1 2
Gas
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
1,975 1 2
1,854 1 2
Nuclear Fuel
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
246 1 2
317 1 2
Other Energy
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
902 1 2
581 1 2
Union Electric Company
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
16,377 1
16,031 1
Accumulated depreciation and amortization
6,766 1
6,614 1
Property and plant, before construction work in progress
9,611 1
9,417 1
Property, Plant and Equipment, Net
10,452 1
10,161 1
Union Electric Company |
Electric
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
15,964 1
15,638 1
Union Electric Company |
Gas
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
413 1
393 1
Union Electric Company |
Nuclear Fuel
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
246 1
317 1
Union Electric Company |
Other Energy
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
595 1
427 1
Ameren Illinois Company
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
6,988 
6,446 
Accumulated depreciation and amortization
1,627 
1,495 
Property and plant, before construction work in progress
5,361 
4,951 
Property, Plant and Equipment, Net
5,589 
5,052 
Ameren Illinois Company |
Electric
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
5,426 
4,985 
Ameren Illinois Company |
Gas
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
1,562 
1,461 
Ameren Illinois Company |
Nuclear Fuel
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
0 
0 
Ameren Illinois Company |
Other Energy
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
228 
101 
Other Affiliates [Member]
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
336 
319 
Accumulated depreciation and amortization
251 
237 
Property and plant, before construction work in progress
85 
82 
Property, Plant and Equipment, Net
164 
135 
Other Affiliates [Member] |
Electric
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
336 
319 
Other Affiliates [Member] |
Gas
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
0 
0 
Other Affiliates [Member] |
Nuclear Fuel
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
0 
0 
Other Affiliates [Member] |
Other Energy
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
$ 79 
$ 53 
Property And Plant, Net (Accrued Capital Expenditures) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
$ 175 1
$ 107 1
$ 97 1
Union Electric Company
 
 
 
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
74 
63 
73 
Ameren Illinois Company
 
 
 
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
86 
37 
18 
Nuclear Fuel
 
 
 
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
8 1
8 1
36 1
Nuclear Fuel |
Union Electric Company
 
 
 
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
$ 8 
$ 8 
$ 36 
Short-Term Debt And Liquidity (Narrative) (Details) (USD $)
12 Months Ended 12 Months Ended
Nov. 14, 2012
Illinois Credit Agreement 2012
Dec. 31, 2013
Illinois Credit Agreement 2012
Maximum
Dec. 31, 2013
Illinois Credit Agreement 2012
Ameren Illinois Company
Nov. 14, 2012
Missouri Credit Agreement 2012
Dec. 31, 2013
Missouri Credit Agreement 2012
Maximum
Dec. 31, 2013
Missouri Credit Agreement 2012
Union Electric Company
Dec. 31, 2013
Credit Agreements 2012
Dec. 31, 2013
Unilateral Borrowing Agreement
Ameren Illinois Company
Dec. 31, 2013
Multiyear Credit Facility
lender
Dec. 31, 2013
Multiyear Credit Facility
Maximum
Dec. 31, 2013
Commercial Paper
Dec. 31, 2013
Utilities
Dec. 31, 2012
Utilities
Line of Credit Facility [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
Line of credit facility, maximum borrowing capacity
$ 1,100,000,000.0 
$ 1,300,000,000.0 
$ 800,000,000 
$ 1,000,000,000 
$ 1,200,000,000.0 
$ 800,000,000 
$ 1,700,000,000.0 
$ 500,000,000 
$ 2,100,000,000.0 
 
 
 
 
Number of lenders
 
 
 
 
 
 
 
 
24 
 
 
 
 
Line of credit facility, maximum borrowing capacity, per lender
 
 
 
 
 
 
 
 
125,000,000 
 
 
 
 
Commercial paper maximum issuance
 
 
 
 
 
 
 
 
 
 
500,000,000 
 
 
Actual debt-to-capital ratio
 
 
0.44 
 
 
0.47 
 
 
0.48 
0.65 
 
 
 
Minimum ratio of consolidated funds from operations plus interest expense to consolidated interest expense as of balance sheet date
 
 
 
 
 
 
 
 
2.0 to 1.0 
 
 
 
 
Current ratio of consolidated funds from operations plus interest expense to consolidated interest expense as of balance sheet date
 
 
 
 
 
 
 
 
5.3 to 1.0 
 
 
 
 
Covenant terms, default provisions, maximum indebtedness
 
 
 
 
 
 
$ 50,000,000 
 
 
 
 
 
 
Short Term Debt, Weighted Average Interest Rate During Period
 
 
 
 
 
 
 
 
 
 
 
0.14% 
0.13% 
Letters of credit portion of aggregate commitment
 
 
 
 
 
 
 
 
25.00% 
 
 
 
 
Short-Term Debt And Liquidity (Schedule Of Maximum Aggregate Amount Available On Credit Agreements) (Details) (USD $)
Nov. 14, 2012
Illinois Credit Agreement 2012
Dec. 31, 2013
Illinois Credit Agreement 2012
Parent Company
Dec. 31, 2013
Illinois Credit Agreement 2012
Ameren Illinois Company
Nov. 14, 2012
Missouri Credit Agreement 2012
Dec. 31, 2013
Missouri Credit Agreement 2012
Parent Company
Dec. 31, 2013
Missouri Credit Agreement 2012
Union Electric Company
Line of Credit Facility [Line Items]
 
 
 
 
 
 
Line of credit facility, maximum borrowing capacity
$ 1,100,000,000.0 
$ 300,000,000 
$ 800,000,000 
$ 1,000,000,000 
$ 500,000,000 
$ 800,000,000 
Short-Term Debt And Liquidity Short-Term Debt And Liquidity (Commercial Paper) (Details) (Commercial Paper, USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Commercial Paper
 
 
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
$ 54 
$ 49 
Commercial paper outstanding
368 
   
Weighted average interest rate
0.56% 
0.92% 
Peak short-term borrowings
$ 368 
$ 229 
Peak short-term borrowings interest rate
0.85% 
1.25% 
Long-Term Debt And Equity Financings (Narrative) (Details) (USD $)
12 Months Ended 12 Months Ended 12 Months Ended 3 Months Ended 3 Months Ended 3 Months Ended 3 Months Ended 1 Months Ended 0 Months Ended 0 Months Ended 0 Months Ended 1 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Oct. 31, 2013
DRPlus
Dec. 31, 2011
DRPlus
Dec. 31, 2011
401 (K)
Dec. 31, 2013
Union Electric Company
Dec. 31, 2012
Union Electric Company
Jan. 31, 2014
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2012
Ameren Illinois Company
Dec. 31, 2013
Ameren Missouri and Ameren Illinois
Dec. 31, 2013
Senior Secured Notes 4.80% Due 2043
Ameren Illinois Company
Secured Debt
Dec. 31, 2012
Senior Secured Notes 4.80% Due 2043
Ameren Illinois Company
Secured Debt
Dec. 31, 2013
Senior Secured Notes 8.875% Due 2013
Ameren Illinois Company
Secured Debt
Dec. 31, 2012
Senior Secured Notes 8.875% Due 2013
Ameren Illinois Company
Secured Debt
Dec. 31, 2013
1993 5.45% Series due 2028
Union Electric Company
Environmental Improvement And Pollution Control Revenue Bonds
Oct. 31, 2013
1993 5.45% Series due 2028
Union Electric Company
Environmental Improvement And Pollution Control Revenue Bonds
Dec. 31, 2012
1993 5.45% Series due 2028
Union Electric Company
Environmental Improvement And Pollution Control Revenue Bonds
Dec. 31, 2013
4.65% Senior secured notes due 2013
Union Electric Company
Secured Debt
Oct. 31, 2013
4.65% Senior secured notes due 2013
Union Electric Company
Secured Debt
Dec. 31, 2012
4.65% Senior secured notes due 2013
Union Electric Company
Secured Debt
Nov. 30, 2012
Series1992 B 6.20% Due 2012
Ameren Illinois Company
Environmental Improvement And Pollution Control Revenue Bonds
Aug. 20, 2012
Senior Secured Notes, 2.70%, Due 2022
Ameren Illinois Company
Secured Debt
Dec. 31, 2013
Senior Secured Notes, 2.70%, Due 2022
Ameren Illinois Company
Secured Debt
Dec. 31, 2012
Senior Secured Notes, 2.70%, Due 2022
Ameren Illinois Company
Secured Debt
Sep. 11, 2012
3.90% Senior secured notes due 2042
Union Electric Company
Secured Debt
Dec. 31, 2013
3.90% Senior secured notes due 2042
Union Electric Company
Secured Debt
Dec. 31, 2012
3.90% Senior secured notes due 2042
Union Electric Company
Secured Debt
Sep. 20, 2012
3.90% Senior secured notes due 2042
Union Electric Company
Secured Debt
Sep. 20, 2012
5.25% Senior secured notes due 2012
Union Electric Company
Secured Debt
Aug. 27, 2012
Series A 2000 5.50% Due 2014
Ameren Illinois Company
Environmental Improvement And Pollution Control Revenue Bonds
Dec. 31, 2013
Minimum
Ameren Illinois Company
Jan. 31, 2014
Subsequent Event
Ameren Illinois Company
Environmental Improvement And Pollution Control Revenue Bonds
Long-Term Debt And Equity Financings [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Preferred stock, authorized
100,000,000 
 
 
 
 
 
7,500,000.0 
 
 
2,600,000.0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Preferred stock, par value
$ 0.01 
 
 
 
 
 
$ 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Preferred stock, shares outstanding
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Common stock, shares authorized
400,000,000 
400,000,000 
 
4,000,000 
6,000,000 
 
150,000,000 
150,000,000 
 
45,000,000 
45,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Common stock, shares issued
   
0 
2,200,000 
 
 
2,200,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Common stock, value of shares issued
   
   
$ 65,000,000 
 
 
$ 65,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Debt instrument face amount
 
 
 
 
 
 
 
 
1,000,000 1
 
 
 
280,000,000 2
0 2
   3
150,000,000 3
1,000,000 4
 
44,000,000 4
   5
 
200,000,000 5
 
400,000,000 
400,000,000 2 6
400,000,000 2 6
485,000,000 
485,000,000 5 7
485,000,000 5 7
485,000,000 
 
 
 
 
Long-term debt interest rate
 
 
 
 
 
 
 
 
 
 
 
 
4.80% 
 
8.875% 
 
5.45% 
5.45% 
 
4.65% 
4.65% 
 
6.20% 
2.70% 
2.70% 
 
3.90% 
3.90% 
 
3.90% 
5.25% 
5.50% 
 
 
Proceeds from issuance of secured debt
 
 
 
 
 
 
 
 
 
 
 
 
276,000,000 
 
 
 
 
 
 
 
 
 
 
397,000,000 
 
 
478,000,000 
 
 
 
 
 
 
 
Redemptions of long-term debt
 
 
 
 
 
 
 
 
 
 
 
 
 
 
150,000,000 
 
44,000,000 
 
 
200,000,000 
 
 
1,000,000 
 
 
 
 
 
 
 
173,000,000 
51,000,000 
 
163,000,000 
Bonds interest rate assumption
 
 
 
 
 
 
 
 
 
 
 
6.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dividend rate on preferred shares, percentage
 
 
 
 
 
 
 
 
 
 
 
7.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Excess in indebtedness upon default of maturity
$ 25,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Common stock equity to capitalization ratio
 
 
 
 
 
 
 
 
 
55.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
30.00% 
 
[2] These notes are collaterally secured by mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the Ameren Illinois mortgage indenture remain outstanding. Redemption, purchase, or maturity of all mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Illinois mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the mortgage bond lien protection associated with these notes to fall away until 2028.
[3] These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under the CILCO mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the CILCO mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the CILCO first mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the first mortgage bond lien protection associated with these notes to fall away until 2023.
[5] These notes are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Missouri mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Missouri first mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the first mortgage bond lien protection associated with these notes to fall away until 2042.
Long-Term Debt And Equity Financings (Schedule Of Long-Term Debt Outstanding) (Details) (USD $)
12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2013
Parent Company
Dec. 31, 2012
Parent Company
Dec. 31, 2013
Parent Company
8.875% Senior unsecured notes due 2014
Dec. 31, 2012
Parent Company
8.875% Senior unsecured notes due 2014
Dec. 31, 2013
Union Electric Company
Dec. 31, 2012
Union Electric Company
Dec. 31, 2013
Union Electric Company
City Of Bowling Green Capital Lease Peno Creek Ct
Dec. 31, 2012
Union Electric Company
City Of Bowling Green Capital Lease Peno Creek Ct
Dec. 31, 2013
Union Electric Company
Audrain County Capital Lease Audrain County Ct
Dec. 31, 2012
Union Electric Company
Audrain County Capital Lease Audrain County Ct
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2012
Ameren Illinois Company
Jan. 31, 2014
Ameren Illinois Company
Sep. 20, 2012
Secured Debt
Union Electric Company
5.25% Senior secured notes due 2012
Dec. 31, 2013
Secured Debt
Union Electric Company
4.65% Senior secured notes due 2013
Oct. 31, 2013
Secured Debt
Union Electric Company
4.65% Senior secured notes due 2013
Dec. 31, 2012
Secured Debt
Union Electric Company
4.65% Senior secured notes due 2013
Dec. 31, 2013
Secured Debt
Union Electric Company
5.50% Senior secured notes due 2014
Dec. 31, 2012
Secured Debt
Union Electric Company
5.50% Senior secured notes due 2014
Dec. 31, 2013
Secured Debt
Union Electric Company
4.75% Senior secured notes due 2015
Dec. 31, 2012
Secured Debt
Union Electric Company
4.75% Senior secured notes due 2015
Dec. 31, 2013
Secured Debt
Union Electric Company
5.40% Senior secured notes due 2016
Dec. 31, 2012
Secured Debt
Union Electric Company
5.40% Senior secured notes due 2016
Dec. 31, 2013
Secured Debt
Union Electric Company
6.40% Senior secured notes due 2017
Dec. 31, 2012
Secured Debt
Union Electric Company
6.40% Senior secured notes due 2017
Dec. 31, 2013
Secured Debt
Union Electric Company
6.00% Senior secured notes due 2018
Dec. 31, 2012
Secured Debt
Union Electric Company
6.00% Senior secured notes due 2018
Sep. 20, 2012
Secured Debt
Union Electric Company
6.00% Senior secured notes due 2018
Dec. 31, 2013
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2018
Dec. 31, 2012
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2018
Sep. 20, 2012
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2018
Dec. 31, 2013
Secured Debt
Union Electric Company
6.70% Senior secured notes due 2019
Dec. 31, 2012
Secured Debt
Union Electric Company
6.70% Senior secured notes due 2019
Sep. 20, 2012
Secured Debt
Union Electric Company
6.70% Senior secured notes due 2019
Dec. 31, 2013
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2019
Dec. 31, 2012
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2019
Sep. 20, 2012
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2019
Dec. 31, 2013
Secured Debt
Union Electric Company
5.00% Senior secured notes due 2020
Dec. 31, 2012
Secured Debt
Union Electric Company
5.00% Senior secured notes due 2020
Dec. 31, 2013
Secured Debt
Union Electric Company
5.50% Senior secured notes due 2034
Dec. 31, 2012
Secured Debt
Union Electric Company
5.50% Senior secured notes due 2034
Dec. 31, 2013
Secured Debt
Union Electric Company
5.30% Senior secured notes due 2037
Dec. 31, 2012
Secured Debt
Union Electric Company
5.30% Senior secured notes due 2037
Dec. 31, 2013
Secured Debt
Union Electric Company
8.45% Senior secured notes due 2039
Dec. 31, 2012
Secured Debt
Union Electric Company
8.45% Senior secured notes due 2039
Dec. 31, 2013
Secured Debt
Union Electric Company
3.90% Senior secured notes due 2042
Dec. 31, 2012
Secured Debt
Union Electric Company
3.90% Senior secured notes due 2042
Sep. 20, 2012
Secured Debt
Union Electric Company
3.90% Senior secured notes due 2042
Sep. 11, 2012
Secured Debt
Union Electric Company
3.90% Senior secured notes due 2042
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 8.875% Due 2013
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 8.875% Due 2013
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.20% Due 2016
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.20% Due 2016
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.25% Due 2016
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.25% Due 2016
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.125% Due 2017
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.125% Due 2017
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.25% Due 2018
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.25% Due 2018
Aug. 27, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.25% Due 2018
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 9.75% Due 2018
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 9.75% Due 2018
Aug. 27, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 9.75% Due 2018
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes, 2.70%, Due 2022
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes, 2.70%, Due 2022
Aug. 20, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes, 2.70%, Due 2022
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.125% Due 2028
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.125% Due 2028
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.70% Due 2036
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.70% Due 2036
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.70% Due 2036
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.70% Due 2036
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 4.80% Due 2043
Dec. 31, 2012
Secured Debt
Ameren Illinois Company
Senior Secured Notes 4.80% Due 2043
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1992 Series due 2022
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1992 Series due 2022
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1993 5.45% Series due 2028
Oct. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1993 5.45% Series due 2028
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1993 5.45% Series due 2028
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1998 Series A due 2033
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1998 Series A due 2033
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1998 Series B due 2033
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1998 Series B due 2033
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1998 Series C due 2033
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1998 Series C due 2033
Nov. 30, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series1992 B 6.20% Due 2012
Aug. 27, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series A 2000 5.50% Due 2014
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series 1993 5.90% Due 2023
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series 1993 5.90% Due 2023
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series 1994 A 5.70% Due 2024
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series 1994 A 5.70% Due 2024
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series C-1 1993 5.95% Due 2026
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series C-1 1993 5.95% Due 2026
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series C-2 1993 5.70% Due 2026
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series C-2 1993 5.70% Due 2026
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series B-1 1993 Due 2028
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series B-1 1993 Due 2028
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series1998A 5.40% Due 2028
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series1998A 5.40% Due 2028
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series1998B 5.40% Due 2028
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series1998B 5.40% Due 2028
Debt Instrument [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Debt instrument face amount
 
 
 
 
$ 425,000,000 
$ 425,000,000 
 
 
 
 
 
 
 
 
$ 1,000,000 1
 
    2
 
$ 200,000,000 2
$ 104,000,000 2
$ 104,000,000 2
$ 114,000,000 2
$ 114,000,000 2
$ 260,000,000 2
$ 260,000,000 2
$ 425,000,000 2
$ 425,000,000 2
$ 179,000,000 2 3
$ 179,000,000 2 3
$ 179,000,000 
$ 199,000,000 2
$ 199,000,000 2
$ 199,000,000 4
$ 329,000,000 2 3
$ 329,000,000 2 3
$ 329,000,000 
$ 244,000,000 2
$ 244,000,000 2
$ 244,000,000 
$ 85,000,000 2
$ 85,000,000 2
$ 184,000,000 2
$ 184,000,000 2
$ 300,000,000 2
$ 300,000,000 2
$ 350,000,000 2 3
$ 350,000,000 2 3
$ 485,000,000 2 3
$ 485,000,000 2 3
$ 485,000,000 
$ 485,000,000 
    5
$ 150,000,000 5
$ 54,000,000 5
$ 54,000,000 5
$ 75,000,000 6
$ 75,000,000 6
$ 250,000,000 6 7
$ 250,000,000 6 7
$ 144,000,000 6 7
$ 144,000,000 6 7
$ 144,000,000 
$ 313,000,000 6 7
$ 313,000,000 6 7
$ 313,000,000 
$ 400,000,000 6 7
$ 400,000,000 6 7
$ 400,000,000 
$ 60,000,000 6
$ 60,000,000 6
$ 61,000,000 6
$ 61,000,000 6
$ 42,000,000 5
$ 42,000,000 5
$ 280,000,000 6
$ 0 6
$ 47,000,000 8 9
$ 47,000,000 8 9
$ 1,000,000 10
 
$ 44,000,000 10
$ 60,000,000 8 9
$ 60,000,000 8 9
$ 50,000,000 8 9
$ 50,000,000 8 9
$ 50,000,000 8 9
$ 50,000,000 8 9
 
 
$ 32,000,000 11
$ 32,000,000 11
$ 36,000,000 1
$ 36,000,000 1
$ 35,000,000 12
$ 35,000,000 12
$ 8,000,000 12
$ 8,000,000 12
$ 17,000,000 12 8
$ 17,000,000 12 8
$ 19,000,000 1
$ 19,000,000 1
$ 33,000,000 1
$ 33,000,000 1
Capital lease obligations
 
 
 
 
 
 
 
 
59,000,000 
64,000,000 
240,000,000 
240,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fair-market value adjustments
 
 
 
 
 
 
 
 
 
 
 
 
4,000,000 
4,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Long-term debt, gross
 
 
 
 
 
 
3,764,000,000 
4,013,000,000 
 
 
 
 
1,863,000,000 
1,733,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Less: Unamortized discount and premium
 
 
   
1,000,000 
 
 
7,000,000 
7,000,000 
 
 
 
 
7,000,000 
6,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Less: Maturities due within one year
(534,000,000)
(355,000,000)
(425,000,000)
   
 
 
(109,000,000)
(205,000,000)
 
 
 
 
   
(150,000,000)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Long-term Debt, Net
$ 5,504,000,000 
$ 5,802,000,000 
    
$ 424,000,000 
 
 
$ 3,648,000,000 
$ 3,801,000,000 
 
 
 
 
$ 1,856,000,000 
$ 1,577,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Long-term debt interest rate
 
 
 
 
8.875% 
 
 
 
 
 
 
 
 
 
 
5.25% 
4.65% 
4.65% 
 
5.50% 
 
4.75% 
 
5.40% 
 
6.40% 
 
6.00% 
 
6.00% 
5.10% 
 
5.10% 
6.70% 
 
6.70% 
5.10% 
 
5.10% 
5.00% 
 
5.50% 
 
5.30% 
 
8.45% 
 
3.90% 
 
3.90% 
3.90% 
8.875% 
 
6.20% 
 
6.25% 
 
6.125% 
 
6.25% 
 
6.25% 
9.75% 
 
9.75% 
2.70% 
 
2.70% 
6.125% 
 
6.70% 
 
6.70% 
 
4.80% 
 
 
 
5.45% 
5.45% 
 
 
 
 
 
 
 
6.20% 
5.50% 
5.90% 
 
5.70% 
 
5.95% 
 
5.70% 
 
 
 
5.40% 
 
5.40% 
 
Long-term debt maturity date
 
 
 
 
2014 
 
 
 
2022 
 
2033 
 
 
 
 
 
2013 
 
 
2014 
 
2015 
 
2016 
 
2017 
 
2018 
 
 
2018 
 
 
2019 
 
 
2019 
 
 
2020 
 
2034 
 
2037 
 
2039 
 
2042 
 
 
 
2013 
 
2016 
 
2016 
 
2017 
 
2018 
 
 
2018 
 
 
2022 
 
 
2028 
 
2036 
 
2036 
 
2043 
 
2022 
 
2028 
 
 
2033 
 
2033 
 
2033 
 
 
 
2023 
 
2024 
 
2026 
 
2026 
 
2028 
 
2028 
 
2028 
 
Debt instrument, interest rate, maximum
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
18.00% 
 
 
 
 
18.00% 
 
18.00% 
 
18.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Redemption price, percentage
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
100.00% 
 
 
 
 
 
 
 
 
 
 
100.00% 
 
100.00% 
 
100.00% 
 
100.00% 
 
100.00% 
 
100.00% 
 
100.00% 
 
[2] These notes are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Missouri mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Missouri first mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the first mortgage bond lien protection associated with these notes to fall away until 2042.
[5] These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under the CILCO mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the CILCO mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the CILCO first mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the first mortgage bond lien protection associated with these notes to fall away until 2023.
[6] These notes are collaterally secured by mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the Ameren Illinois mortgage indenture remain outstanding. Redemption, purchase, or maturity of all mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Illinois mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the mortgage bond lien protection associated with these notes to fall away until 2028.
Long-Term Debt And Equity Financings (Schedule Of Average Interest Rates) (Details)
12 Months Ended
Dec. 31, 2013
1992 Series due 2022
Union Electric Company
Dec. 31, 2012
1992 Series due 2022
Union Electric Company
Dec. 31, 2013
1998 Series A due 2033
Union Electric Company
Dec. 31, 2012
1998 Series A due 2033
Union Electric Company
Dec. 31, 2013
1998 Series B due 2033
Union Electric Company
Dec. 31, 2012
1998 Series B due 2033
Union Electric Company
Dec. 31, 2013
1998 Series C due 2033
Union Electric Company
Dec. 31, 2012
1998 Series C due 2033
Union Electric Company
Dec. 31, 2013
Series B-1 1993 Due 2028
Ameren Illinois Company
Dec. 31, 2012
Series B-1 1993 Due 2028
Ameren Illinois Company
Dec. 31, 2013
Secured Debt
3.90% Senior secured notes due 2042
Union Electric Company
Sep. 20, 2012
Secured Debt
3.90% Senior secured notes due 2042
Union Electric Company
Sep. 11, 2012
Secured Debt
3.90% Senior secured notes due 2042
Union Electric Company
Debt Instrument [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
Long-term debt interest rate
 
 
 
 
 
 
 
 
 
 
3.90% 
3.90% 
3.90% 
Debt instrument, interest rate during period
0.17% 
0.30% 
0.34% 
0.65% 
0.33% 
0.64% 
0.34% 
0.64% 
0.14% 
0.22% 
 
 
 
Long-Term Debt And Equity Financings (Schedule Of Maturities Of Long-Term Debt) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Debt Instrument [Line Items]
 
 
2014
$ 534 
 
2015
120 
 
2016
395 
 
2017
681 
 
2018
840 
 
Thereafter
3,478 
 
Total
6,048 
 
Parent Company
 
 
Debt Instrument [Line Items]
 
 
2014
425 
 
2015
   
 
2016
   
 
2017
   
 
2018
   
 
Thereafter
   
 
Total
425 
 
Unamortized discount and premium
   
1 
Union Electric Company
 
 
Debt Instrument [Line Items]
 
 
2014
109 1
 
2015
120 1
 
2016
266 1
 
2017
431 1
 
2018
383 1
 
Thereafter
2,455 1
 
Total
3,764 1
 
Unamortized discount and premium
7 
7 
Ameren Illinois Company
 
 
Debt Instrument [Line Items]
 
 
2014
   1 2
 
2015
   1 2
 
2016
129 1 2
 
2017
250 1 2
 
2018
457 1 2
 
Thereafter
1,023 1 2
 
Total
1,859 1 2
 
Unamortized discount and premium
7 
6 
Fair value adjustments
$ 4 
 
Long-Term Debt And Equity Financings (Schedule Of Outstanding Preferred Stock) (Details) (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Long-Term Debt And Equity Financings [Line Items]
 
 
Preferred stock, par value
$ 0.01 
 
Preferred stock, authorized
100,000,000 
 
Preferred stock, shares outstanding
0 
 
Preferred stock, issued
$ 142 
$ 142 
Preferred stock, voluntary liquidation
$ 106 
 
Union Electric Company
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Preferred stock, par value
$ 1 
 
Preferred stock, authorized
7,500,000 
 
Preferred stock, issued
80 
80 
Union Electric Company |
Par Value $100 [Member]
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Preferred stock, par value
$ 100 
 
Preferred stock, authorized
25,000,000 
 
Union Electric Company |
$3.50 Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, per-dollar amount
$ 3.50 
 
Preferred stock, shares outstanding
130,000 
 
Preferred stock, redemption price per share
$ 110 
 
Preferred stock, issued
13 
13 
Union Electric Company |
$3.70 Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, per-dollar amount
$ 3.70 
 
Preferred stock, shares outstanding
40,000 
 
Preferred stock, redemption price per share
$ 105 
 
Preferred stock, issued
4 
4 
Union Electric Company |
$4.00 Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, per-dollar amount
$ 4.00 
 
Preferred stock, shares outstanding
150,000 
 
Preferred stock, redemption price per share
$ 106 
 
Preferred stock, issued
15 
15 
Union Electric Company |
$4.30 Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, per-dollar amount
$ 4.30 
 
Preferred stock, shares outstanding
40,000 
 
Preferred stock, redemption price per share
$ 105 
 
Preferred stock, issued
4 
4 
Union Electric Company |
$4.50 Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, per-dollar amount
$ 4.50 
 
Preferred stock, shares outstanding
213,595 
 
Preferred stock, redemption price per share
$ 110 1
 
Preferred stock, issued
21 
21 
Union Electric Company |
$4.56 Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, per-dollar amount
$ 4.56 
 
Preferred stock, shares outstanding
200,000 
 
Preferred stock, redemption price per share
$ 102 
 
Preferred stock, issued
20 
20 
Union Electric Company |
$4.75 Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, per-dollar amount
$ 4.75 
 
Preferred stock, shares outstanding
20,000 
 
Preferred stock, redemption price per share
$ 102 
 
Preferred stock, issued
2 
2 
Union Electric Company |
$5.50 Series A
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, per-dollar amount
$ 5.50 
 
Preferred stock, shares outstanding
14,000 
 
Preferred stock, redemption price per share
$ 110 
 
Preferred stock, issued
1 
1 
Ameren Illinois Company
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Preferred stock, authorized
2,600,000 
 
Preferred stock, issued
62 
62 
Ameren Illinois Company |
Par Value $100 [Member]
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Preferred stock, par value
$ 100 
 
Preferred stock, authorized
2,000,000 
 
Ameren Illinois Company |
4.00% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
4.00% 
 
Preferred stock, shares outstanding
144,275 
 
Preferred stock, redemption price per share
$ 101 
 
Preferred stock, issued
14 
14 
Ameren Illinois Company |
4.08% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
4.08% 
 
Preferred stock, shares outstanding
45,224 
 
Preferred stock, redemption price per share
$ 103 
 
Preferred stock, issued
5 
5 
Ameren Illinois Company |
4.20% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
4.20% 
 
Preferred stock, shares outstanding
23,655 
 
Preferred stock, redemption price per share
$ 104 
 
Preferred stock, issued
2 
2 
Ameren Illinois Company |
4.25% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
4.25% 
 
Preferred stock, shares outstanding
50,000 
 
Preferred stock, redemption price per share
$ 102 
 
Preferred stock, issued
5 
5 
Ameren Illinois Company |
4.26% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
4.26% 
 
Preferred stock, shares outstanding
16,621 
 
Preferred stock, redemption price per share
$ 103 
 
Preferred stock, issued
2 
2 
Ameren Illinois Company |
4.42% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
4.42% 
 
Preferred stock, shares outstanding
16,190 
 
Preferred stock, redemption price per share
$ 103 
 
Preferred stock, issued
2 
2 
Ameren Illinois Company |
4.70% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
4.70% 
 
Preferred stock, shares outstanding
18,429 
 
Preferred stock, redemption price per share
$ 103 
 
Preferred stock, issued
2 
2 
Ameren Illinois Company |
4.90% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
4.90% 
 
Preferred stock, shares outstanding
73,825 
 
Preferred stock, redemption price per share
$ 102 
 
Preferred stock, issued
7 
7 
Ameren Illinois Company |
4.92% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
4.92% 
 
Preferred stock, shares outstanding
49,289 
 
Preferred stock, redemption price per share
$ 104 
 
Preferred stock, issued
5 
5 
Ameren Illinois Company |
5.16% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
5.16% 
 
Preferred stock, shares outstanding
50,000 
 
Preferred stock, redemption price per share
$ 102 
 
Preferred stock, issued
5 
5 
Ameren Illinois Company |
6.625% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
6.625% 
 
Preferred stock, shares outstanding
124,274 
 
Preferred stock, redemption price per share
$ 100 
 
Preferred stock, issued
12 
12 
Ameren Illinois Company |
7.75% Series
 
 
Long-Term Debt And Equity Financings [Line Items]
 
 
Dividend rate on preferred shares, percentage
7.75% 
 
Preferred stock, shares outstanding
4,542 
 
Preferred stock, redemption price per share
$ 100 
 
Preferred stock, issued
$ 1 
$ 1 
Long-Term Debt And Equity Financings (Aggregate Principal Amount of Senior Notes) (Details) (USD $)
12 Months Ended 12 Months Ended 0 Months Ended 0 Months Ended 0 Months Ended 0 Months Ended 0 Months Ended 0 Months Ended
Dec. 31, 2013
Ameren Illinois Company
Jan. 31, 2014
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
2.70% Senior Notes Due 2022
Aug. 27, 2012
Ameren Illinois Company
Secured Debt
Senior Secured Notes 9.75% Due 2018
Dec. 31, 2013
Ameren Illinois Company
Secured Debt
Senior Secured Notes 9.75% Due 2018
Dec. 31, 2012
Ameren Illinois Company
Secured Debt
Senior Secured Notes 9.75% Due 2018
Aug. 27, 2012
Ameren Illinois Company
Secured Debt
Senior Secured Notes 6.25% Due 2018
Dec. 31, 2013
Ameren Illinois Company
Secured Debt
Senior Secured Notes 6.25% Due 2018
Dec. 31, 2012
Ameren Illinois Company
Secured Debt
Senior Secured Notes 6.25% Due 2018
Sep. 20, 2012
Union Electric Company
Secured Debt
6.00% Senior secured notes due 2018
Dec. 31, 2013
Union Electric Company
Secured Debt
6.00% Senior secured notes due 2018
Dec. 31, 2012
Union Electric Company
Secured Debt
6.00% Senior secured notes due 2018
Sep. 20, 2012
Union Electric Company
Secured Debt
6.70% Senior secured notes due 2019
Dec. 31, 2013
Union Electric Company
Secured Debt
6.70% Senior secured notes due 2019
Dec. 31, 2012
Union Electric Company
Secured Debt
6.70% Senior secured notes due 2019
Sep. 20, 2012
Union Electric Company
Secured Debt
5.10% Senior secured notes due 2018
Dec. 31, 2013
Union Electric Company
Secured Debt
5.10% Senior secured notes due 2018
Dec. 31, 2012
Union Electric Company
Secured Debt
5.10% Senior secured notes due 2018
Sep. 20, 2012
Union Electric Company
Secured Debt
5.10% Senior secured notes due 2019
Dec. 31, 2013
Union Electric Company
Secured Debt
5.10% Senior secured notes due 2019
Dec. 31, 2012
Union Electric Company
Secured Debt
5.10% Senior secured notes due 2019
Dec. 31, 2013
Union Electric Company
Secured Debt
3.90% Senior secured notes due 2042
Dec. 31, 2012
Union Electric Company
Secured Debt
3.90% Senior secured notes due 2042
Sep. 20, 2012
Union Electric Company
Secured Debt
3.90% Senior secured notes due 2042
Sep. 11, 2012
Union Electric Company
Secured Debt
3.90% Senior secured notes due 2042
Sep. 20, 2012
Maximum
Union Electric Company
Secured Debt
5.10% Senior secured notes due 2018
Debt Instrument [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Payments of Debt Issuance Costs
 
 
$ 21,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Long-term debt interest rate
 
 
2.70% 
9.75% 
9.75% 
 
6.25% 
6.25% 
 
6.00% 
6.00% 
 
6.70% 
6.70% 
 
5.10% 
5.10% 
 
5.10% 
5.10% 
 
3.90% 
 
3.90% 
3.90% 
 
Amortization of Financing Costs
15,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Principal Amount Repurchased
 
 
 
87,000,000 
 
 
194,000,000 
 
 
71,000,000 
 
 
121,000,000 
 
 
1,000,000 1
 
 
56,000,000 
 
 
 
 
 
 
 
Premium Plus Accrued and Unpaid Interest
 
 
 
36,000,000 2
 
 
47,000,000 2
 
 
19,000,000 3
 
 
35,000,000 3
 
 
 
 
 
12,000,000 3
 
 
 
 
 
 
1,000,000 
Principal Amount Outstanding After Tender Offer
 
$ 1,000,000 4
$ 400,000,000 
$ 313,000,000 
$ 313,000,000 5 6
$ 313,000,000 5 6
$ 144,000,000 
$ 144,000,000 5 6
$ 144,000,000 5 6
$ 179,000,000 
$ 179,000,000 7 8
$ 179,000,000 7 8
$ 329,000,000 
$ 329,000,000 7 8
$ 329,000,000 7 8
$ 199,000,000 1
$ 199,000,000 8
$ 199,000,000 8
$ 244,000,000 
$ 244,000,000 8
$ 244,000,000 8
$ 485,000,000 7 8
$ 485,000,000 7 8
$ 485,000,000 
$ 485,000,000 
 
[6] These notes are collaterally secured by mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the Ameren Illinois mortgage indenture remain outstanding. Redemption, purchase, or maturity of all mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Illinois mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the mortgage bond lien protection associated with these notes to fall away until 2028.
[8] These notes are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Missouri mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Missouri first mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the first mortgage bond lien protection associated with these notes to fall away until 2042.
Long-Term Debt and Equity Financings (Schedule of Debt Redemptions) (Details) (Ameren Illinois Company, USD $)
0 Months Ended 0 Months Ended 1 Months Ended
Jan. 31, 2014
Dec. 31, 2013
2.70% Senior Notes Due 2022
Aug. 27, 2012
Secured Debt
Senior Secured Notes 9.75% Due 2018
Dec. 31, 2013
Secured Debt
Senior Secured Notes 9.75% Due 2018
Dec. 31, 2012
Secured Debt
Senior Secured Notes 9.75% Due 2018
Aug. 27, 2012
Secured Debt
Senior Secured Notes 6.25% Due 2018
Dec. 31, 2013
Secured Debt
Senior Secured Notes 6.25% Due 2018
Dec. 31, 2012
Secured Debt
Senior Secured Notes 6.25% Due 2018
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Series 1993 5.90% Due 2023
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Series 1993 5.90% Due 2023
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Series 1994 A 5.70% Due 2024
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Series 1994 A 5.70% Due 2024
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Series C-1 1993 5.95% Due 2026
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Series C-1 1993 5.95% Due 2026
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Series C-2 1993 5.70% Due 2026
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Series C-2 1993 5.70% Due 2026
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Series1998A 5.40% Due 2028
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Series1998A 5.40% Due 2028
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Series1998B 5.40% Due 2028
Dec. 31, 2012
Environmental Improvement And Pollution Control Revenue Bonds
Series1998B 5.40% Due 2028
Jan. 31, 2014
Subsequent Event
Environmental Improvement And Pollution Control Revenue Bonds
Jan. 31, 2014
Subsequent Event
Environmental Improvement And Pollution Control Revenue Bonds
Series 1993 5.90% Due 2023
Jan. 31, 2014
Subsequent Event
Environmental Improvement And Pollution Control Revenue Bonds
Series 1994 A 5.70% Due 2024
Jan. 31, 2014
Subsequent Event
Environmental Improvement And Pollution Control Revenue Bonds
Series C-1 1993 5.95% Due 2026
Jan. 31, 2014
Subsequent Event
Environmental Improvement And Pollution Control Revenue Bonds
Series C-2 1993 5.70% Due 2026
Jan. 31, 2014
Subsequent Event
Environmental Improvement And Pollution Control Revenue Bonds
Series1998A 5.40% Due 2028
Jan. 31, 2014
Subsequent Event
Environmental Improvement And Pollution Control Revenue Bonds
Series1998B 5.40% Due 2028
Debt Instrument [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Redemptions of long-term debt
 
 
$ 87,000,000 
 
 
$ 194,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
$ 163,000,000 
$ 32,000,000 1
$ 36,000,000 1
$ 35,000,000 
$ 8,000,000 
$ 19,000,000 
$ 33,000,000 
Debt instrument face amount
$ 1,000,000 2
$ 400,000,000 
$ 313,000,000 
$ 313,000,000 3 4
$ 313,000,000 3 4
$ 144,000,000 
$ 144,000,000 3 4
$ 144,000,000 3 4
$ 32,000,000 5
$ 32,000,000 5
$ 36,000,000 2
$ 36,000,000 2
$ 35,000,000 6
$ 35,000,000 6
$ 8,000,000 6
$ 8,000,000 6
$ 19,000,000 2
$ 19,000,000 2
$ 33,000,000 2
$ 33,000,000 2
 
 
 
 
 
 
 
[4] These notes are collaterally secured by mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the Ameren Illinois mortgage indenture remain outstanding. Redemption, purchase, or maturity of all mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Illinois mortgage bonds and senior secured notes currently outstanding, and assuming no early retirement of any series of such securities in full, we do not expect the mortgage bond lien protection associated with these notes to fall away until 2028.
Long-Term Debt and Equity Financings (Schedule of Required and Actual Debt Ratios) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Union Electric Company
 
Debt Instrument [Line Items]
 
Bonds Issuable Based On Coverage Ratio
$ 3,831 1
Preferred Stock Issuable Based On Coverage Ratio
2,228 
Retired Bond Capacity
729 
Union Electric Company |
Actual Interest Coverage Ratio
 
Debt Instrument [Line Items]
 
Interest Coverage Ratio
4.5 
Dividend Coverage Ratio
116.5 
Ameren Illinois Company
 
Debt Instrument [Line Items]
 
Bonds Issuable Based On Coverage Ratio
3,565 1 2
Preferred Stock Issuable Based On Coverage Ratio
203 
Retired Bond Capacity
$ 365 
Ameren Illinois Company |
Actual Interest Coverage Ratio
 
Debt Instrument [Line Items]
 
Interest Coverage Ratio
6.8 
Dividend Coverage Ratio
2.4 
Minimum |
Union Electric Company |
Required Dividend Coverage Ratio
 
Debt Instrument [Line Items]
 
Interest Coverage Ratio
2.0 3
Dividend Coverage Ratio
2.5 4
Minimum |
Ameren Illinois Company |
Required Dividend Coverage Ratio
 
Debt Instrument [Line Items]
 
Interest Coverage Ratio
2.0 3
Dividend Coverage Ratio
1.5 4
Other Income And Expenses (Other Income And Expenses) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Other Nonoperating Income (Expense) [Line Items]
 
 
 
Allowance for equity funds used during construction
$ 37 1
$ 36 1
$ 34 1
Interest income on industrial development revenue bonds
27 1
28 1
28 1
Interest and dividend income
3 1
4 1 2
3 1
Other
2 1
2 1
3 1
Total miscellaneous income
69 1
70 1
68 1
Donations
12 1
24 1 3
8 1
Other
14 1
13 1
15 1
Total miscellaneous expense
26 1
37 1
23 1
Union Electric Company
 
 
 
Other Nonoperating Income (Expense) [Line Items]
 
 
 
Allowance for equity funds used during construction
31 
31 
30 
Interest income on industrial development revenue bonds
27 
28 
28 
Interest and dividend income
   
4 2
2 
Other
   
   
1 
Total miscellaneous income
58 
63 
61 
Donations
4 
9 
3 
Other
7 
5 
7 
Total miscellaneous expense
11 
14 
10 
Ameren Illinois Company
 
 
 
Other Nonoperating Income (Expense) [Line Items]
 
 
 
Allowance for equity funds used during construction
6 
5 
4 
Interest and dividend income
2 
   
1 
Other
2 
2 
2 
Total miscellaneous income
10 
7 
7 
Donations
4 
11 3
1 
Other
5 
6 
5 
Total miscellaneous expense
9 
17 
6 
Illinois Science and Energy Innovation Trust |
Ameren Illinois Company
 
 
 
Other Nonoperating Income (Expense) [Line Items]
 
 
 
One-time Donation
$ 7.5 
 
 
Derivative Financial Instruments (Open Gross Derivative Volumes By Commodity Type) (Details)
Dec. 31, 2013
gal
Dec. 31, 2012
gal
Fuel Oils
 
 
Derivative [Line Items]
 
 
Quantity
66,000,000 1
70,000,000 1
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
136,000,000 
147,000,000 
Power
 
 
Derivative [Line Items]
 
 
Quantity
14,000,000 
25,000,000 
Uranium
 
 
Derivative [Line Items]
 
 
Quantity
796,000 
446,000 
Union Electric Company |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Quantity
66,000,000 1
70,000,000 1
Union Electric Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
28,000,000 
19,000,000 
Union Electric Company |
Power
 
 
Derivative [Line Items]
 
 
Quantity
3,000,000 
11,000,000 
Union Electric Company |
Uranium
 
 
Derivative [Line Items]
 
 
Quantity
796,000 
446,000 
Ameren Illinois Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
108,000,000 
128,000,000 
Ameren Illinois Company |
Power
 
 
Derivative [Line Items]
 
 
Quantity
11,000,000 
14,000,000 
Derivative Financial Instruments (Derivative Instruments Carrying Value) (Details) (Not Designated As Hedging Instrument, USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Derivative [Line Items]
 
 
Derivative assets
$ 34 1
$ 29 1
Derivative liabilities
178 1
230 1
Fuel Oils |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
6 1
8 1
Fuel Oils |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
3 1
4 1
Fuel Oils |
MTM derivative liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 1
2 1
Fuel Oils |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
   1
Fuel Oils |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
1 1
2 1
Natural Gas |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
2 1
1 1
Natural Gas |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
 
1 1
Natural Gas |
MTM derivative liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
32 1
64 1
Natural Gas |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
   1
Natural Gas |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
25 1
45 1
Power |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
23 1
14 1
Power |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
 
1 1
Power |
MTM derivative liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
13 1
25 1
Power |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
   1
Power |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
99 1
90 1
Uranium |
MTM derivative liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
5 1
1 1
Uranium |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
 
Uranium |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
1 1
1 1
Union Electric Company
 
 
Derivative [Line Items]
 
 
Derivative assets
33 1
28 1
Derivative liabilities
24 1
25 1
Union Electric Company |
Fuel Oils |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
6 1
8 1
Union Electric Company |
Fuel Oils |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
3 1
4 1
Union Electric Company |
Fuel Oils |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 1
2 1
Union Electric Company |
Fuel Oils |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
1 1
2 1
Union Electric Company |
Natural Gas |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
1 1
   1
Union Electric Company |
Natural Gas |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
 
1 1
Union Electric Company |
Natural Gas |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
5 1
8 1
Union Electric Company |
Natural Gas |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
6 1
7 1
Union Electric Company |
Power |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
23 1
14 1
Union Electric Company |
Power |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
 
1 1
Union Electric Company |
Power |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
4 1
4 1
Union Electric Company |
Power |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
   1
Union Electric Company |
Uranium |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
5 1
1 1
Union Electric Company |
Uranium |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
1 1
1 1
Ameren Illinois Company
 
 
Derivative [Line Items]
 
 
Derivative assets
1 1
1 1
Derivative liabilities
154 1
205 1
Ameren Illinois Company |
Fuel Oils |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
   1
   1
Ameren Illinois Company |
Fuel Oils |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
   1
   1
Ameren Illinois Company |
Fuel Oils |
MTM derivative liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
   1
Ameren Illinois Company |
Fuel Oils |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
   1
Ameren Illinois Company |
Natural Gas |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
1 1
1 1
Ameren Illinois Company |
Natural Gas |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
 
   1
Ameren Illinois Company |
Natural Gas |
MTM derivative liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
27 1
56 1
Ameren Illinois Company |
Natural Gas |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
   1
Ameren Illinois Company |
Natural Gas |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
19 1
38 1
Ameren Illinois Company |
Power |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
   1
   1
Ameren Illinois Company |
Power |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
 
   1
Ameren Illinois Company |
Power |
MTM derivative liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
9 1
21 1
Ameren Illinois Company |
Power |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
   1
Ameren Illinois Company |
Power |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
99 1
90 1
Ameren Illinois Company |
Uranium |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
   1
   1
Derivative Financial Instruments (Cumulative Amount Of Pretax Net Gains (Losses) On All Derivative Instruments In OCI) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
$ 216 
$ 100 
Current losses deferred as regulatory assets
156 
247 
Power
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
23 
 
Current losses deferred as regulatory assets
13 
 
Fuel Oils
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
3 
 
Current losses deferred as regulatory assets
1 
 
Natural Gas
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
2 
 
Current losses deferred as regulatory assets
32 
 
Uranium
 
 
Derivative [Line Items]
 
 
Current losses deferred as regulatory assets
5 
 
Regulatory Liabilities Or Assets |
Power
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(89)1
(99)1
Regulatory Liabilities Or Assets |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
2 2
4 2
Regulatory Liabilities Or Assets |
Natural Gas
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(55)3
(107)3
Regulatory Liabilities Or Assets |
Uranium
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(6)4
(2)4
Union Electric Company
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
57 
18 
Current losses deferred as regulatory assets
118 
163 
Union Electric Company |
Power
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
23 
 
Current losses deferred as regulatory assets
4 
 
Union Electric Company |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
3 
 
Current losses deferred as regulatory assets
1 
 
Union Electric Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
1 
 
Current losses deferred as regulatory assets
5 
 
Union Electric Company |
Uranium
 
 
Derivative [Line Items]
 
 
Current losses deferred as regulatory assets
5 
 
Union Electric Company |
Regulatory Liabilities Or Assets |
Power
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
19 1
12 1
Union Electric Company |
Regulatory Liabilities Or Assets |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
2 2
4 2
Union Electric Company |
Regulatory Liabilities Or Assets |
Natural Gas
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(10)3
(14)3
Union Electric Company |
Regulatory Liabilities Or Assets |
Uranium
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(6)4
(2)4
Ameren Illinois Company
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
159 
82 
Current losses deferred as regulatory assets
38 
84 
Ameren Illinois Company |
Power
 
 
Derivative [Line Items]
 
 
Current losses deferred as regulatory assets
9 
 
Ameren Illinois Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
1 
 
Current losses deferred as regulatory assets
27 
 
Ameren Illinois Company |
Regulatory Liabilities Or Assets |
Power
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(108)1
(111)1
Ameren Illinois Company |
Regulatory Liabilities Or Assets |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
   2
   2
Ameren Illinois Company |
Regulatory Liabilities Or Assets |
Natural Gas
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(45)3
(93)3
Ameren Illinois Company |
Regulatory Liabilities Or Assets |
Uranium
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
   4
   4
Derivative Financial Instruments Derivative Financial Instruments (Offsetting Derivative Assets and Liabilities) (Details) (Commodity Contract, USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
$ 34 1
$ 29 1
Derivative Instruments
10 
10 
Cash Collateral Received/Posted
   2
   2
Net Amount
24 
19 
Gross Amounts Recognized in the Balance Sheet
178 1
230 1
Derivative Instruments
10 
10 
Cash Collateral Received/Posted
24 2
65 2
Net Amount
144 
155 
Union Electric Company
 
 
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
33 1
28 1
Derivative Instruments
9 
9 
Cash Collateral Received/Posted
   2
   2
Net Amount
24 
19 
Gross Amounts Recognized in the Balance Sheet
24 1
25 1
Derivative Instruments
9 
9 
Cash Collateral Received/Posted
9 2
7 2
Net Amount
6 
9 
Ameren Illinois Company
 
 
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
1 
1 
Derivative Instruments
1 
1 
Cash Collateral Received/Posted
   2
   2
Net Amount
0 
0 
Gross Amounts Recognized in the Balance Sheet
154 1
205 1
Derivative Instruments
1 
1 
Cash Collateral Received/Posted
15 2
58 2
Net Amount
$ 138 
$ 146 
Derivative Financial Instruments (Maximum Exposure If Counterparties Fail To Perform On Contracts) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Concentration Risk [Line Items]
 
 
Maximum exposure to counterparties related to derivative contracts
$ 13 
$ 23 
Union Electric Company
 
 
Concentration Risk [Line Items]
 
 
Maximum exposure to counterparties related to derivative contracts
12 
22 
Ameren Illinois Company
 
 
Concentration Risk [Line Items]
 
 
Maximum exposure to counterparties related to derivative contracts
$ 1 
$ 1 
Derivative Financial Instruments (Potential Loss On Counterparty Exposures) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Concentration Risk [Line Items]
 
 
Potential loss on counterparty exposures related to derivative contracts
$ 6 
$ 15 
Union Electric Company
 
 
Concentration Risk [Line Items]
 
 
Potential loss on counterparty exposures related to derivative contracts
$ 6 
$ 15 
Derivative Financial Instruments (Cash Flow Hedges) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Derivative [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
$ 1,322 
$ 1,638 
$ 1,403 
$ 1,475 
$ 1,258 
$ 1,709 
$ 1,402 
$ 1,412 
$ 5,838 
$ 5,781 
$ 6,148 
Derivative Financial Instruments (Derivatives That Qualify For Regulatory Deferral) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
$ 56 1
$ (112)1
Fuel Oils
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
(2)
(15)
Natural Gas
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
52 
84 
Power
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
10 1
(180)1
Uranium
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
(4)
(1)
Union Electric Company
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
5 
(15)
Union Electric Company |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
(2)
(15)
Union Electric Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
4 
10 
Union Electric Company |
Power
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
7 
(9)
Union Electric Company |
Uranium
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
(4)
(1)
Ameren Illinois Company
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
51 
103 
Ameren Illinois Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
48 
74 
Ameren Illinois Company |
Power
 
 
Derivative [Line Items]
 
 
Gain (Loss) RecognizedIn Regulatory Liabilitiesor Regulatory Assets
$ 3 
$ 29 
Fair Value Measurements (Schedule of Valuation Process and Unobservable Inputs) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Discounted Cash Flow |
Minimum |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
 
0.21% 1
Counterparty credit risk
0.26% 2 3
0.12% 2 3
Credit risk
 
2.00% 2 3
Discounted Cash Flow |
Minimum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.39% 2 3
0.22% 2 3
Credit risk
2.00% 2 3
2.00% 2 3
Average bid/ask consensus peak and off-peak pricing
25 3
22 3
Estimated auction price for FTRs
(1,594)1
(281)1
Nodal basis
(3)3
(5)3
Discounted Cash Flow |
Minimum |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
34 1
43 1
Discounted Cash Flow |
Minimum |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
 
0.21% 1
Counterparty credit risk
0.26% 2 3
0.12% 2 3
Credit risk
 
2.00% 2 3
Discounted Cash Flow |
Minimum |
Union Electric Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.39% 2 3
0.22% 2 3
Credit risk
2.00% 2 3
2.00% 2 3
Average bid/ask consensus peak and off-peak pricing
25 3
24 3
Estimated auction price for FTRs
(1,594)1
(281)1
Nodal basis
(3)3
(5)3
Discounted Cash Flow |
Minimum |
Union Electric Company |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
34 1
43 1
Discounted Cash Flow |
Minimum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Credit risk
2.00% 2 3
5.00% 2 3
Nodal basis
(4)1
(5)1
Average bid/ask consensus pricing
27 1
22 1
Discounted Cash Flow |
Maximum |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
 
0.60% 1
Counterparty credit risk
2.00% 2 3
1.00% 2 3
Credit risk
 
2.00% 2 3
Discounted Cash Flow |
Maximum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.50% 2 3
1.00% 2 3
Credit risk
2.00% 2 3
5.00% 2 3
Average bid/ask consensus peak and off-peak pricing
51 3
47 3
Estimated auction price for FTRs
945 1
1,851 1
Nodal basis
(1)3
(1)3
Discounted Cash Flow |
Maximum |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
41 1
46 1
Discounted Cash Flow |
Maximum |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
 
0.60% 1
Counterparty credit risk
2.00% 2 3
1.00% 2 3
Credit risk
 
2.00% 2 3
Discounted Cash Flow |
Maximum |
Union Electric Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.50% 2 3
1.00% 2 3
Credit risk
2.00% 2 3
2.00% 2 3
Average bid/ask consensus peak and off-peak pricing
51 3
56 3
Estimated auction price for FTRs
945 1
1,851 1
Nodal basis
(1)3
(1)3
Discounted Cash Flow |
Maximum |
Union Electric Company |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
41 1
46 1
Discounted Cash Flow |
Maximum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Credit risk
2.00% 2 3
5.00% 2 3
Nodal basis
0 1
(1)1
Average bid/ask consensus pricing
36 1
47 1
Discounted Cash Flow |
Weighted Average |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
 
0.44% 1
Counterparty credit risk
1.00% 2 3
1.00% 2 3
Credit risk
 
2.00% 2 3
Discounted Cash Flow |
Weighted Average |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.42% 2 3
1.00% 2 3
Credit risk
2.00% 2 3
5.00% 2 3
Average bid/ask consensus peak and off-peak pricing
32 3
31 3
Estimated auction price for FTRs
305 1
178 1
Nodal basis
(2)3
(3)3
Discounted Cash Flow |
Weighted Average |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
36 1
44 1
Discounted Cash Flow |
Weighted Average |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
 
0.44% 1
Counterparty credit risk
1.00% 2 3
1.00% 2 3
Credit risk
 
2.00% 2 3
Discounted Cash Flow |
Weighted Average |
Union Electric Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.42% 2 3
1.00% 2 3
Credit risk
2.00% 2 3
2.00% 2 3
Average bid/ask consensus peak and off-peak pricing
40 3
36 3
Estimated auction price for FTRs
305 1
178 1
Nodal basis
(2)3
(2)3
Discounted Cash Flow |
Weighted Average |
Union Electric Company |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
36 1
44 1
Discounted Cash Flow |
Weighted Average |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Credit risk
2.00% 2 3
5.00% 2 3
Nodal basis
(2)1
(3)1
Average bid/ask consensus pricing
30 1
30 1
Option Model |
Minimum |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
10.00% 1
7.00% 1
Option Model |
Minimum |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
10.00% 1
7.00% 1
Option Model |
Maximum |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
35.00% 1
27.00% 1
Option Model |
Maximum |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
35.00% 1
27.00% 1
Option Model |
Weighted Average |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
16.00% 1
24.00% 1
Option Model |
Weighted Average |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
16.00% 1
24.00% 1
Fundamental Energy Production Model |
Minimum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
3.00% 1 4
 
Estimated future gas prices
4 1
4 1
Fundamental Energy Production Model |
Minimum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
3.00% 1 4
 
Estimated future gas prices
4 1
4 1
Fundamental Energy Production Model |
Maximum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
4.00% 1 4
 
Estimated future gas prices
5 1
8 1
Fundamental Energy Production Model |
Maximum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
4.00% 1 4
 
Estimated future gas prices
5 1
8 1
Fundamental Energy Production Model |
Weighted Average |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
4.00% 1 4
 
Estimated future gas prices
5 1
6 1
Fundamental Energy Production Model |
Weighted Average |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
4.00% 1 4
 
Estimated future gas prices
5 1
6 1
Contract Price Allocation |
Minimum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
5 1
5 1
Contract Price Allocation |
Minimum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
5 1
5 1
Contract Price Allocation |
Maximum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
7 1
7 1
Contract Price Allocation |
Maximum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
7 1
7 1
Contract Price Allocation |
Weighted Average |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
6 1
6 1
Contract Price Allocation |
Weighted Average |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
6 1
6 1
Derivative liabilities |
Fuel Oils
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
$ (3)5
$ (3)5
Derivative liabilities |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(110)5 6
(114)5 6
Derivative liabilities |
Uranium
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(6)5
(2)5
Derivative liabilities |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(3)5
(3)5
Derivative liabilities |
Union Electric Company |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(2)5 6
(3)5 6
Derivative liabilities |
Union Electric Company |
Uranium
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(6)5
(2)5
Derivative liabilities |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(108)5 6
(111)5 6
Derivative assets |
Fuel Oils
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
8 5
8 5
Derivative assets |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
21 5 6
14 5 6
Derivative assets |
Uranium
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
   5
   5
Derivative assets |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
8 5
8 5
Derivative assets |
Union Electric Company |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
21 5 6
14 5 6
Derivative assets |
Union Electric Company |
Uranium
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
   5
   5
Derivative assets |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
   5 6
   5 6
Fair Value Measurements (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Counterparty default risk liability valuation adjustment related to derivative contracts
$ 3 
$ 7 
Union Electric Company
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Counterparty default risk liability valuation adjustment related to derivative contracts
1 
1 
Ameren Illinois Company
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Counterparty default risk liability valuation adjustment related to derivative contracts
$ 3 
$ 7 
Fair Value Measurements (Schedule Of Fair Value Hierarchy Of Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
$ 494 
$ 406 1
Assets
528 
435 
Excluded receivables, payables, and accrued income, net
 
2 
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
335 
265 
Assets
336 
269 
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
159 
141 
Assets
163 
144 
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Assets
29 
22 
Cash And Cash Equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
3 
1 
Cash And Cash Equivalents |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
3 
1 
Cash And Cash Equivalents |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Cash And Cash Equivalents |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
34 2
29 2
Derivative liabilities
178 2
230 2
Commodity Contract |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
4 2
Derivative liabilities
3 2
8 2
Commodity Contract |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
4 2
3 2
Derivative liabilities
56 2
103 2
Commodity Contract |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
29 2
22 2
Derivative liabilities
119 2
119 2
Commodity Contract |
Fuel Oils
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
9 2
12 2
Derivative liabilities
3 2
4 2
Commodity Contract |
Fuel Oils |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
4 2
Derivative liabilities
   2
1 2
Commodity Contract |
Fuel Oils |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
   2
   2
Commodity Contract |
Fuel Oils |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
8 2
8 2
Derivative liabilities
3 2
3 2
Commodity Contract |
Natural Gas
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
2 2
2 2
Derivative liabilities
57 2
109 2
Commodity Contract |
Natural Gas |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
3 2
7 2
Commodity Contract |
Natural Gas |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
2 2
2 2
Derivative liabilities
54 2
102 2
Commodity Contract |
Natural Gas |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
   2
   2
Commodity Contract |
Power
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
23 2
15 2
Derivative liabilities
112 2
115 2
Commodity Contract |
Power |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
   2
   2
Commodity Contract |
Power |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
2 2
1 2
Derivative liabilities
2 2
1 2
Commodity Contract |
Power |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
21 2
14 2
Derivative liabilities
110 2
114 2
Commodity Contract |
Uranium
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
6 2
2 2
Commodity Contract |
Uranium |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
   2
   2
Commodity Contract |
Uranium |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
   2
   2
Commodity Contract |
Uranium |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
6 2
2 2
Equity Securities |
U.S. Large Capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
332 
264 
Equity Securities |
U.S. Large Capitalization |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
332 
264 
Equity Securities |
U.S. Large Capitalization |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Equity Securities |
U.S. Large Capitalization |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
Corporate Bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
52 
47 
Debt Securities |
Corporate Bonds |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
Corporate Bonds |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
52 
47 
Debt Securities |
Corporate Bonds |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
Municipal Bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
1 
Debt Securities |
Municipal Bonds |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
Municipal Bonds |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
1 
Debt Securities |
Municipal Bonds |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
U.S. treasury and agency securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
94 
81 
Debt Securities |
U.S. treasury and agency securities |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
U.S. treasury and agency securities |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
94 
81 
Debt Securities |
U.S. treasury and agency securities |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
Asset-Backed Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
10 
11 
Debt Securities |
Asset-Backed Securities |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
Asset-Backed Securities |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
10 
11 
Debt Securities |
Asset-Backed Securities |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
Other debt securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
1 
Debt Securities |
Other debt securities |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Debt Securities |
Other debt securities |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
1 
Debt Securities |
Other debt securities |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
494 
406 1
Assets
527 
434 
Union Electric Company |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
335 
265 
Assets
336 
269 
Union Electric Company |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
159 
141 
Assets
162 
143 
Union Electric Company |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Assets
29 
22 
Union Electric Company |
Cash And Cash Equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
3 
1 
Union Electric Company |
Cash And Cash Equivalents |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
3 
1 
Union Electric Company |
Cash And Cash Equivalents |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Cash And Cash Equivalents |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
33 2
28 2
Derivative liabilities
24 2
25 2
Union Electric Company |
Commodity Contract |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
4 2
Derivative liabilities
3 2
8 2
Union Electric Company |
Commodity Contract |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
3 2
2 2
Derivative liabilities
10 2
9 2
Union Electric Company |
Commodity Contract |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
29 2
22 2
Derivative liabilities
11 2
8 2
Union Electric Company |
Commodity Contract |
Fuel Oils
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
9 2
12 2
Derivative liabilities
3 2
4 2
Union Electric Company |
Commodity Contract |
Fuel Oils |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
4 2
Derivative liabilities
   2
1 2
Union Electric Company |
Commodity Contract |
Fuel Oils |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
   2
   2
Union Electric Company |
Commodity Contract |
Fuel Oils |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
8 2
8 2
Derivative liabilities
3 2
3 2
Union Electric Company |
Commodity Contract |
Natural Gas
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 2
Derivative liabilities
11 2
15 2
Union Electric Company |
Commodity Contract |
Natural Gas |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
3 2
7 2
Union Electric Company |
Commodity Contract |
Natural Gas |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 2
Derivative liabilities
8 2
8 2
Union Electric Company |
Commodity Contract |
Natural Gas |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
   2
   2
Union Electric Company |
Commodity Contract |
Power
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
23 2
15 2
Derivative liabilities
4 2
4 2
Union Electric Company |
Commodity Contract |
Power |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
   2
   2
Union Electric Company |
Commodity Contract |
Power |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
2 2
1 2
Derivative liabilities
2 2
1 2
Union Electric Company |
Commodity Contract |
Power |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
21 2
14 2
Derivative liabilities
2 2
3 2
Union Electric Company |
Commodity Contract |
Uranium
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
6 2
2 2
Union Electric Company |
Commodity Contract |
Uranium |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
   2
   2
Union Electric Company |
Commodity Contract |
Uranium |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
   2
   2
Union Electric Company |
Commodity Contract |
Uranium |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
6 2
2 2
Union Electric Company |
Equity Securities |
U.S. Large Capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
332 
264 
Union Electric Company |
Equity Securities |
U.S. Large Capitalization |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
332 
264 
Union Electric Company |
Equity Securities |
U.S. Large Capitalization |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Equity Securities |
U.S. Large Capitalization |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
Corporate Bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
52 
47 
Union Electric Company |
Debt Securities |
Corporate Bonds |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
Corporate Bonds |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
52 
47 
Union Electric Company |
Debt Securities |
Corporate Bonds |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
Municipal Bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
1 
Union Electric Company |
Debt Securities |
Municipal Bonds |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
Municipal Bonds |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
1 
Union Electric Company |
Debt Securities |
Municipal Bonds |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
U.S. treasury and agency securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
94 
81 
Union Electric Company |
Debt Securities |
U.S. treasury and agency securities |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
U.S. treasury and agency securities |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
94 
81 
Union Electric Company |
Debt Securities |
U.S. treasury and agency securities |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
Asset-Backed Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
10 
11 
Union Electric Company |
Debt Securities |
Asset-Backed Securities |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
Asset-Backed Securities |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
10 
11 
Union Electric Company |
Debt Securities |
Asset-Backed Securities |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
Other debt securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
1 
Union Electric Company |
Debt Securities |
Other debt securities |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Union Electric Company |
Debt Securities |
Other debt securities |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
1 
Union Electric Company |
Debt Securities |
Other debt securities |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
   
   
Ameren Illinois Company |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 
1 
Derivative liabilities
154 2
205 2
Ameren Illinois Company |
Commodity Contract |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
   2
   2
Ameren Illinois Company |
Commodity Contract |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
46 2
94 2
Ameren Illinois Company |
Commodity Contract |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
108 2
111 2
Ameren Illinois Company |
Commodity Contract |
Natural Gas
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 2
Derivative liabilities
46 2
94 2
Ameren Illinois Company |
Commodity Contract |
Natural Gas |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
   2
   2
Ameren Illinois Company |
Commodity Contract |
Natural Gas |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 2
Derivative liabilities
46 2
94 2
Ameren Illinois Company |
Commodity Contract |
Natural Gas |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
   2
   2
Ameren Illinois Company |
Commodity Contract |
Power
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
108 2
111 2
Ameren Illinois Company |
Commodity Contract |
Power |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
   2
   2
Ameren Illinois Company |
Commodity Contract |
Power |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
   2
   2
Ameren Illinois Company |
Commodity Contract |
Power |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
$ 108 2
$ 111 2
Fair Value Measurements (Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level 3 In The Fair Value Hierarchy) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Fuel Oils
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
$ 5 
$ 3 
Included in regulatory assets/liabilities
   
(1)
Total realized and unrealized gains (losses)
0 
(1)
Purchases
3 
7 
Sales
(1)
(3)
Settlements
(2)
(2)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3
 
1 
Ending balance
5 
5 
Change in unrealized gains (losses) related to assets/liabilities still held
0 
(1)
Natural Gas
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
0 
(174)
Included in regulatory assets/liabilities
(1)
(27)
Total realized and unrealized gains (losses)
(1)
(27)
Purchases
1 
 
Settlements
 
16 
Transfers out of Level 3
 
185 
Ending balance
0 
0 
Change in unrealized gains (losses) related to assets/liabilities still held
0 
0 
Power
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(100)1
81 1
Included in regulatory assets/liabilities
(15)
(175)1
Total realized and unrealized gains (losses)
(15)
(175)1
Purchases
40 
21 1
Sales
 
(1)1
Settlements
(15)
(22)1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3
(3)
 
Transfers out of Level 3
4 
(4)1
Ending balance
(89)
(100)1
Change in unrealized gains (losses) related to assets/liabilities still held
(25)
(175)
Uranium
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(2)
(1)
Included in regulatory assets/liabilities
(3)
(2)
Total realized and unrealized gains (losses)
(3)
(2)
Purchases
(2)
 
Settlements
1 
1 
Ending balance
(6)
(2)
Change in unrealized gains (losses) related to assets/liabilities still held
(2)
(1)
Union Electric Company |
Fuel Oils
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
5 
3 
Included in regulatory assets/liabilities
   
(1)
Total realized and unrealized gains (losses)
0 
(1)
Purchases
3 
7 
Sales
(1)
(3)
Settlements
(2)
(2)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3
 
1 
Ending balance
5 
5 
Change in unrealized gains (losses) related to assets/liabilities still held
0 
(1)
Union Electric Company |
Natural Gas
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
0 
(14)
Included in regulatory assets/liabilities
   
(2)
Total realized and unrealized gains (losses)
   
(2)
Purchases
   
 
Settlements
 
1 
Transfers out of Level 3
 
15 
Ending balance
0 
0 
Change in unrealized gains (losses) related to assets/liabilities still held
0 
0 
Union Electric Company |
Power
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
11 
21 
Included in regulatory assets/liabilities
3 
11 
Total realized and unrealized gains (losses)
3 
11 
Purchases
40 
21 
Sales
 
(1)
Settlements
(36)
(37)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3
(3)
 
Transfers out of Level 3
4 
(4)
Ending balance
19 
11 
Change in unrealized gains (losses) related to assets/liabilities still held
(1)
0 
Union Electric Company |
Uranium
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(2)
(1)
Included in regulatory assets/liabilities
(3)
(2)
Total realized and unrealized gains (losses)
(3)
(2)
Purchases
(2)
 
Settlements
1 
1 
Ending balance
(6)
(2)
Change in unrealized gains (losses) related to assets/liabilities still held
(2)
(1)
Ameren Illinois Company |
Natural Gas
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
0 
(160)
Included in regulatory assets/liabilities
(1)
(25)
Total realized and unrealized gains (losses)
(1)
(25)
Purchases
1 
 
Settlements
 
15 
Transfers out of Level 3
 
170 
Ending balance
0 
0 
Change in unrealized gains (losses) related to assets/liabilities still held
0 
0 
Ameren Illinois Company |
Power
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(111)
(140)
Included in regulatory assets/liabilities
(18)
(226)
Total realized and unrealized gains (losses)
(18)
(226)
Purchases
   
   
Sales
 
   
Settlements
21 
255 
Transfers out of Level 3
   
   
Ending balance
(108)
(111)
Change in unrealized gains (losses) related to assets/liabilities still held
$ (24)
$ (191)2
Fair Value Measurements (Schedule Of Transfers Between Fair Value Hierarchy Levels) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Net fair value of Level 3 transfers
$ 1 
$ 182 
Fuel Oils
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Transfers into Level 3/Transfers out of Level 1
   
1 
Natural Gas
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Transfers out of Level 3/Transfers into Level 2
   
185 
Power
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Transfer into Level 3/Transfers out of Level 2
(3)
   
Transfers out of Level 3/Transfers into Level 2
4 
(4)
Union Electric Company
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Net fair value of Level 3 transfers
1 
12 
Union Electric Company |
Fuel Oils
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Transfers into Level 3/Transfers out of Level 1
   
1 
Union Electric Company |
Natural Gas
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Transfers out of Level 3/Transfers into Level 2
   
15 
Union Electric Company |
Power
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Transfer into Level 3/Transfers out of Level 2
(3)
   
Transfers out of Level 3/Transfers into Level 2
4 
(4)
Ameren Illinois Company |
Natural Gas
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Transfers out of Level 3/Transfers into Level 2
    
$ 170 
Fair Value Measurements (Schedule Of Carrying Amounts And Estimated Fair Values Of Long-Term Debt And Preferred Stock) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Carrying Amount
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term Debt and Capital Lease Obligations
$ 6,038 1
$ 6,157 1
Preferred stock
142 1
142 1
Fair Value
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt and capital lease obligations (including current portion)
6,584 1
7,110 1
Preferred stock
118 1
123 1
Union Electric Company |
Carrying Amount
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term Debt and Capital Lease Obligations
3,757 
4,006 
Preferred stock
80 
80 
Union Electric Company |
Fair Value
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt and capital lease obligations (including current portion)
4,124 
4,625 
Preferred stock
71 
74 
Ameren Illinois Company |
Carrying Amount
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term Debt and Capital Lease Obligations
1,856 
1,727 
Preferred stock
62 
62 
Ameren Illinois Company |
Fair Value
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt and capital lease obligations (including current portion)
2,028 
2,020 
Preferred stock
$ 47 
$ 49 
Nuclear Decommissioning Trust Fund Investments (Fair Values Of Investments In Debt And Equity Securities In Nuclear Decommissioning Trust Fund) (Details) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
$ 297,000,000 
$ 281,000,000 
Gross unrealized gains
203,000,000 
138,000,000 
Gross unrealized loss
6,000,000 
11,000,000 
Fair Value
494,000,000 
408,000,000 
Debt Securities
 
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
157,000,000 
133,000,000 
Gross unrealized gains
4,000,000 
8,000,000 
Gross unrealized loss
2,000,000 
 
Fair Value
159,000,000 
141,000,000 
Equity Securities
 
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
137,000,000 
145,000,000 
Gross unrealized gains
199,000,000 
130,000,000 
Gross unrealized loss
4,000,000 
11,000,000 
Fair Value
332,000,000 
264,000,000 
Cash
 
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
3,000,000 
1,000,000 
Fair Value
3,000,000 
1,000,000 
Other Debt And Equity Securities
 
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
 
2,000,000 1
Fair Value
 
$ 2,000,000 1
Nuclear Decommissioning Trust Fund Investments (Costs And Fair Values Of Investments In Debt Securities In Nuclear Decommissioning Trust Fund According To Contractual Maturities) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
 
Cost, Less than 5 years
$ 93 
Cost, 5 years to 10 years
31 
Cost, Due after 10 years
33 
Cost, Total
157 
Fair Value, Less than 5 years
94 
Fair Value, 5 years to 10 years
32 
Fair Value, Due after 10 years
33 
Fair Value, Total
$ 159 
Nuclear Decommissioning Trust Fund Investments (Fair Value And The Gross Unrealized Losses Of The Available-For-Sale Securities Held In Nuclear Decommissioning Trust Fund) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
Less than 12 months, fair value
$ 78 
Less than 12 months, gross unrealized losses
2 
12 months or greater, fair value
7 
12 months or greater, gross unrealized losses
4 
Total, fair value
85 
Total, gross unrealized losses
6 
Debt Securities
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
Less than 12 months, fair value
72 
Less than 12 months, gross unrealized losses
2 
Total, fair value
72 
Total, gross unrealized losses
2 
Equity Securities
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
Less than 12 months, fair value
6 
12 months or greater, fair value
7 
12 months or greater, gross unrealized losses
4 
Total, fair value
13 
Total, gross unrealized losses
$ 4 
Callaway Energy Center (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended 12 Months Ended
Dec. 31, 2013
mill
Dec. 31, 2012
Dec. 31, 2011
Jun. 30, 2011
Dec. 31, 2011
Reduction To Depreciation And Amortization
Dec. 31, 2011
Reduction To Other Operations And Maintenance
Dec. 31, 2012
Reduction In Property And Plant
Dec. 31, 2013
Nuclear Plant
Mar. 30, 2014
Nuclear Plant
Loss Contingencies [Line Items]
 
 
 
 
 
 
 
 
 
Nwf Fee Number Of Mills
1 
 
 
 
 
 
 
 
 
Settlement payment
 
 
 
$ 11 
$ 2 
$ 2 
$ 1 
$ 6 
 
Gain Contingency, Unrecorded Amount
 
 
 
 
 
 
 
 
15 
Useful life
 
 
 
 
 
 
 
40 years 
 
Annual decommissioning costs included in costs of service
 
$ 7 
$ 7 
 
 
 
 
$ 7 
 
MoPSC requirement to file updated cost study and funding analysis for decommissioning Callaway energy center
3 years 
 
 
 
 
 
 
 
 
Retirement Benefits (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
bond
Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation, Change in Discount Rate
0.75% 
 
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments
$ 19 1 2
 
Defined Benefit Plan, Funded Status of Plan
461 3
1,143 3
Number of high-quality corporate bonds
500 
 
Defined benefit plan, estimated future employer contributions during the next five years
270 
 
Actual return in excess of (or less than) expected return, percentage
25.00% 
 
Expected return on plan assets, period
4 years 
 
Amortization basis, straight line, in years
10 years 
 
Pension Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments
12 2
 
Defined Benefit Plan, Funded Status of Plan
(439)3
(924)3
Assumptions used calculating net periodic benefit cost, expected long-term return on assets in 2013
7.25% 
 
Postretirement Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments
7 2
 
Defined Benefit Plan, Funded Status of Plan
(22)3
(219)3
Assumptions used calculating net periodic benefit cost, expected long-term return on assets in 2013
7.00% 
 
Minimum
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined benefit plan, estimated future employer contributions during the next five years
20 
 
Maximum
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined benefit plan, estimated future employer contributions during the next five years
100 
 
Private equity
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Number of limited partnerships in private equity funds
9 
 
Minimum invested capital within limited partnership investments
0.1 
 
Maximum invested capital within limited partnership investments
$ 5 
 
Union Electric Company |
Pension Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Future funding requirement, percentage
52.00% 
 
Ameren Illinois Company |
Pension Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Future funding requirement, percentage
47.00% 
 
Retirement Benefits (Summary Of Benefit Liability Recorded) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
 
 
Benefit liability recorded on the balance sheet
$ 461 1
$ 1,143 1
Union Electric Company
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Benefit liability recorded on the balance sheet
191 
464 
Ameren Illinois Company
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Benefit liability recorded on the balance sheet
$ 198 
$ 408 
Retirement Benefits (Funded Status Of Benefit Plans And Amounts Included In Regulatory Assets And OCI) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Change in plan assets:
 
 
 
Funded status – deficiency
$ (461)1
$ (1,143)1
 
Amounts recognized in the balance sheet consist of:
 
 
 
Noncurrent liability
466 
1,138 
 
Net liability recognized
461 1
1,143 1
 
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Accumulated benefit obligation at end of year
3,698 1
3,829 1
 
Change in benefit obligation:
 
 
 
Net benefit obligation at beginning of year
4,051 1
3,764 1
 
Service cost
91 1 2
81 1 2
73 2
Interest cost
163 1 2
166 1 2
175 2
Participant contributions
   1
   1
 
Actuarial (gain) loss
(207)1
240 1
 
Curtailment gain(c)
   2 3
   2 3
 
Settlement
   1 4
   5
 
Benefits paid
(198)1
(200)1
 
Net benefit obligation at end of year
3,900 1
4,051 1
3,764 1
Change in plan assets:
 
 
 
Fair value of plan assets at beginning of year
3,127 1
2,814 1
 
Actual return on plan assets
376 1
385 1
 
Employer contributions
156 1
128 1
96 1
Participant contributions
   1
   1
 
Benefits paid
(198)1
(200)1
 
Fair value of plan assets at end of year
3,461 1
3,127 1
2,814 1
Funded status – deficiency
439 1
924 1
 
Accrued benefit cost at December 31
439 1
924 1
 
Amounts recognized in the balance sheet consist of:
 
 
 
Noncurrent asset
   
   
 
Current liability(f)
3 1 6
3 1 6
 
Noncurrent liability
436 1
921 1
 
Net liability recognized
439 1
924 1
 
Amounts recognized in regulatory assets consist of:
 
 
 
Net actuarial (gain) loss
282 1
699 1
 
Prior service cost (credit)
(7)1
(6)1
 
Amounts (pretax) recognized in accumulated OCI consist of:
 
 
 
Net actuarial (gain) loss
17 1
65 1
 
Prior service cost (credit)
   1
(14)1
 
Total
292 1
744 1
 
Postretirement Benefits
 
 
 
Change in benefit obligation:
 
 
 
Net benefit obligation at beginning of year
1,157 1
1,145 1
 
Service cost
22 1 2
22 1 2
20 2
Interest cost
46 1 2
47 1 2
54 2
Participant contributions
16 1
16 1
 
Actuarial (gain) loss
(76)1
(10)1
 
Curtailment gain(c)
(3)2 3
   2 3
 
Settlement
5 1 4
   5
 
Benefits paid
(64)1
(69)1
 
Early retiree reinsurance program receipt
   1
2 1
 
Federal subsidy on benefits paid
3 1
4 1
 
Net benefit obligation at end of year
1,096 1
1,157 1
1,145 1
Change in plan assets:
 
 
 
Fair value of plan assets at beginning of year
938 1
836 1
 
Actual return on plan assets
156 1
104 1
 
Employer contributions
25 1
45 1
129 1
Federal subsidy on benefits paid
3 1
4 1
 
Early retiree reinsurance program receipt
   1
2 1
 
Participant contributions
16 1
16 1
 
Benefits paid
(64)1
(69)1
 
Fair value of plan assets at end of year
1,074 1
938 1
836 1
Funded status – deficiency
22 1
219 1
 
Accrued benefit cost at December 31
22 1
219 1
 
Amounts recognized in the balance sheet consist of:
 
 
 
Noncurrent asset
9 1 7
   
 
Current liability(f)
1 1 6
2 1 6
 
Noncurrent liability
30 1
217 1
 
Net liability recognized
22 1
219 1
 
Amounts recognized in regulatory assets consist of:
 
 
 
Net actuarial (gain) loss
(71)1
103 1
 
Prior service cost (credit)
(20)1
(24)1
 
Amounts (pretax) recognized in accumulated OCI consist of:
 
 
 
Net actuarial (gain) loss
(12)1
5 1
 
Prior service cost (credit)
(1)1
(6)1
 
Total
$ (104)1
$ 78 1
 
Retirement Benefits (Assumptions Used To Determine Benefit Obligations) (Details)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Pension Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Discount rate at measurement date
4.75% 
4.00% 
Increase in future compensation
3.50% 
3.50% 
Medical cost trend rate (initial)
   
   
Medical cost trend rate (ultimate)
   
   
Postretirement Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Discount rate at measurement date
4.75% 
4.00% 
Increase in future compensation
3.50% 
3.50% 
Medical cost trend rate (initial)
5.00% 
5.00% 
Medical cost trend rate (ultimate)
5.00% 
5.00% 
Retirement Benefits (Cash Contributions Made To Benefit Plans) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
$ 156 1
$ 128 1
$ 96 1
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
25 1
45 1
129 1
Union Electric Company |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
60 
52 
43 
Union Electric Company |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
10 
9 
9 
Ameren Illinois Company |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
50 
46 
28 
Ameren Illinois Company |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
11 
35 
118 
Other |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
46 
30 
25 
Other |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
$ 4 
$ 1 
$ 2 
Retirement Benefits (Target Allocation Of The Plans' Asset Categories) (Details)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Pension Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined Benefit Plan, Actual Plan Asset Allocations
100.00% 
100.00% 
Pension Benefits |
Cash And Cash Equivalents
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
0.00% 
 
Maximum Target Allocation
5.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
2.00% 
2.00% 
Pension Benefits |
Equity Securities
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
50.00% 
 
Maximum Target Allocation
60.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
58.00% 
54.00% 
Pension Benefits |
U.S. large capitalization
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
29.00% 
 
Maximum Target Allocation
39.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
36.00% 
34.00% 
Pension Benefits |
U.S. small and mid-capitalization
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
2.00% 
 
Maximum Target Allocation
12.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
8.00% 
7.00% 
Pension Benefits |
International and emerging markets
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
9.00% 
 
Maximum Target Allocation
19.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
14.00% 
13.00% 
Pension Benefits |
Debt Securities
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
35.00% 
 
Maximum Target Allocation
45.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
36.00% 
39.00% 
Pension Benefits |
Real estate
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
0.00% 
 
Maximum Target Allocation
9.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
4.00% 
4.00% 
Pension Benefits |
Private equity
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
0.00% 
 
Maximum Target Allocation
4.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
1.00% 1
1.00% 
Postretirement Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined Benefit Plan, Actual Plan Asset Allocations
100.00% 
100.00% 
Postretirement Benefits |
Cash And Cash Equivalents
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
0.00% 
 
Maximum Target Allocation
10.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
4.00% 
4.00% 
Postretirement Benefits |
Equity Securities
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
55.00% 
 
Maximum Target Allocation
65.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
63.00% 
62.00% 
Postretirement Benefits |
U.S. large capitalization
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
33.00% 
 
Maximum Target Allocation
43.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
41.00% 
40.00% 
Postretirement Benefits |
U.S. small and mid-capitalization
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
3.00% 
 
Maximum Target Allocation
13.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
8.00% 
8.00% 
Postretirement Benefits |
International
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
10.00% 
 
Maximum Target Allocation
20.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
14.00% 
14.00% 
Postretirement Benefits |
Debt Securities
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Minimum Target Allocation
30.00% 
 
Maximum Target Allocation
40.00% 
 
Defined Benefit Plan, Actual Plan Asset Allocations
33.00% 
34.00% 
Retirement Benefits (Fair Value Of Plan Assets Utilizing Fair Value Hierarchy) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Real estate
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Defined Benefit Plan, Purchases, Sales, and Settlements
$ 4 
$ 3 
 
Fair value of plan assets
131 
118 
108 
Private equity
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Defined Benefit Plan, Purchases, Sales, and Settlements
(6)
(5)
 
Fair value of plan assets
15 
19 
23 
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
3,461 1
3,127 1
2,814 1
Pension Benefits |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
528 
452 
 
Pension Benefits |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
2,865 
2,611 
 
Pension Benefits |
Significant Other Unobservable Inputs (Level 3)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
146 
137 
 
Pension Benefits |
Cash And Cash Equivalents
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
44 
29 
 
Pension Benefits |
Cash And Cash Equivalents |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
5 
1 
 
Pension Benefits |
Cash And Cash Equivalents |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
39 
28 
 
Pension Benefits |
U.S. large capitalization
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,269 
1,090 
 
Pension Benefits |
U.S. large capitalization |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
107 
83 
 
Pension Benefits |
U.S. large capitalization |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,162 
1,007 
 
Pension Benefits |
U.S. small and mid-capitalization
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
273 
235 
 
Pension Benefits |
U.S. small and mid-capitalization |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
273 
235 
 
Pension Benefits |
U.S. small and mid-capitalization |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
0 
0 
 
Pension Benefits |
International and emerging markets
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
515 
435 
 
Pension Benefits |
International and emerging markets |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
143 
134 
 
Pension Benefits |
International and emerging markets |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
372 
301 
 
Pension Benefits |
Corporate Bonds
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
860 
832 
 
Pension Benefits |
Corporate Bonds |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
860 
832 
 
Pension Benefits |
Municipal Bonds
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
149 
176 
 
Pension Benefits |
Municipal Bonds |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
149 
176 
 
Pension Benefits |
U.S. treasury and agency securities
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
256 
250 
 
Pension Benefits |
U.S. treasury and agency securities |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
256 
250 
 
Pension Benefits |
Asset-Backed Securities |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
10 
 
 
Pension Benefits |
Other
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
27 
17 
 
Pension Benefits |
Other |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
27 
17 
 
Pension Benefits |
Real estate
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
131 
118 
 
Pension Benefits |
Real estate |
Significant Other Unobservable Inputs (Level 3)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
131 
118 
 
Pension Benefits |
Private equity
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
15 
19 
 
Pension Benefits |
Private equity |
Significant Other Unobservable Inputs (Level 3)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
15 
19 
 
Pension Benefits |
Derivative assets
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1 
0 
 
Pension Benefits |
Derivative assets |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1 
0 
 
Pension Benefits |
Derivative liabilities
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
(1)
(1)
 
Pension Benefits |
Derivative liabilities |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
(1)
(1)
 
Pension Benefits |
Medical benefit assets
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
(112)2
(102)2
 
Pension Benefits |
Net receivables
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
34 3
29 3
 
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,074 1
938 1
836 1
Postretirement Benefits |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
490 
439 
 
Postretirement Benefits |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
511 
443 
 
Postretirement Benefits |
Cash And Cash Equivalents
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
77 
83 
 
Postretirement Benefits |
Cash And Cash Equivalents |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
77 
83 
 
Postretirement Benefits |
Cash And Cash Equivalents |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
0 
0 
 
Postretirement Benefits |
U.S. large capitalization
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
398 
333 
 
Postretirement Benefits |
U.S. large capitalization |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
297 
245 
 
Postretirement Benefits |
U.S. large capitalization |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
101 
88 
 
Postretirement Benefits |
U.S. small and mid-capitalization
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
77 
66 
 
Postretirement Benefits |
U.S. small and mid-capitalization |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
77 
66 
 
Postretirement Benefits |
International
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
135 
114 
 
Postretirement Benefits |
International |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
39 
45 
 
Postretirement Benefits |
International |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
96 
69 
 
Postretirement Benefits |
Corporate Bonds
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
89 
88 
 
Postretirement Benefits |
Corporate Bonds |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
89 
88 
 
Postretirement Benefits |
Municipal Bonds
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
103 
91 
 
Postretirement Benefits |
Municipal Bonds |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
103 
91 
 
Postretirement Benefits |
U.S. treasury and agency securities
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
72 
67 
 
Postretirement Benefits |
U.S. treasury and agency securities |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
72 
67 
 
Postretirement Benefits |
Asset-Backed Securities
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
10 
18 
 
Postretirement Benefits |
Asset-Backed Securities |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
 
18 
 
Postretirement Benefits |
Other
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
40 
22 
 
Postretirement Benefits |
Other |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
40 
22 
 
Postretirement Benefits |
Medical benefit assets
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
112 2
102 2
 
Postretirement Benefits |
Net payables
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
(39)4
(46)4
 
Includes Medical Benefit Component Under Section401 H And Excludes Payables Related To Pending Security Sales [Member] |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,074 
938 
 
Excludes Medical Benefit Component Under Section401 H And Includes Receivables Related To Pending Security Sales [Member] |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
3,461 
3,127 
 
Excludes Medical Benefit Component Under Section401 H And Excludes Payables Related To Pending Security Sales [Member] |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,001 
882 
 
Includes Medical Benefit Component Under Section401 H And Excludes Receivables Related To Pending Security Sales [Member] |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
$ 3,539 
$ 3,200 
 
Retirement Benefits (Changes In The Fair Value Of Plan Assets Classified As Level 3) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Real estate
 
 
Change in plan assets:
 
 
Fair value of plan assets at beginning of year
$ 118 
$ 108 
Actual Return on Plan Assets Related to Assets Still Held at the Reporting Date
9 
7 
Purchases, Sales and Settlements, net
4 
3 
Fair value of plan assets at end of year
131 
118 
Private equity
 
 
Change in plan assets:
 
 
Fair value of plan assets at beginning of year
19 
23 
Actual Return on Plan Assets Related to Assets Still Held at the Reporting Date
(9)
(7)
Actual Return on Plan Assets Related to Assets Sold During the Period
11 
8 
Purchases, Sales and Settlements, net
(6)
(5)
Fair value of plan assets at end of year
$ 15 
$ 19 
Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Curtailment loss
$ (19)1 2
 
 
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Service cost
91 1 3
81 1 3
73 1
Interest cost
163 1 3
166 1 3
175 1
Expected return on plan assets
(218)1
(208)1
(211)1
Transition obligation
   1
   1
   1
Prior service cost
(2)1
(3)1
(1)1
Actuarial loss
87 1
75 1
41 1
Curtailment loss
(12)1
 
 
Net periodic benefit cost(b)
109 1 2
111 1 4
77 1 4
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Service cost
22 1 3
22 1 3
20 1
Interest cost
46 1 3
47 1 3
54 1
Expected return on plan assets
(62)1
(56)1
(50)1
Transition obligation
   1
2 1
2 1
Prior service cost
(6)1
(6)1
(6)1
Actuarial loss
8 1
5 1
3 1
Curtailment loss
(7)1
 
 
Net periodic benefit cost(b)
1 1 2
14 1 4
23 1 4
New Ameren Energy Resources Company, LLC |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost(b)
6 1 2
9 1 2
7 1 2
New Ameren Energy Resources Company, LLC |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost(b)
$ 7 1 2
    1 2
    1 2
Retirement Benefits (Summary Of Estimated Amortizable Amounts From Regulatory Assets and Accumulated OCI Into Net Periodic Benefit Cost) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Pension Benefits
 
Defined Benefit Plan Disclosure [Line Items]
 
Prior service cost (credit)
$ (1)1
Net actuarial loss
60 1
Net actuarial (gain) loss
1 1
Net periodic benefit cost
60 1
Postretirement Benefits
 
Defined Benefit Plan Disclosure [Line Items]
 
Prior service cost (credit)
(4)1
Net actuarial loss
9 1
Net actuarial (gain) loss
(2)1
Net periodic benefit cost
$ 3 1
Retirement Benefits (Summary Of Benefit Plan Costs Incurred) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
$ 109 1 2
$ 111 1 3
$ 77 1 3
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
1 1 2
14 1 3
23 1 3
Union Electric Company |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
69 
63 
51 
Union Electric Company |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
8 
10 
11 
Ameren Illinois Company |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
41 
37 
16 
Ameren Illinois Company |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
   
4 
11 
Other |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
5 
2 
3 
Other |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
   
   
1 
Continuing Operations [Member] |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
115 4
102 4
70 4
Continuing Operations [Member] |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
$ 8 4
$ 14 4
$ 23 4
Retirement Benefits (Schedule Of Expected Payments From Qualified Trust And Company Funds) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Pension Benefits |
Paid From Qualified Trust
 
Defined Benefit Plan Disclosure [Line Items]
 
2014
$ 247 
2015
249 
2016
255 
2017
260 
2018
264 
2019 - 2023
1,342 
Pension Benefits |
Paid From Company Funds
 
Defined Benefit Plan Disclosure [Line Items]
 
2014
3 
2015
3 
2016
3 
2017
3 
2018
3 
2019 - 2023
14 
Postretirement Benefits
 
Defined Benefit Plan Disclosure [Line Items]
 
2014, Federal Subsidy
3 
2015, Federal Subsidy
4 
2016, Federal Subsidy
4 
2017, Federal Subsidy
4 
2018, Federal Subsidy
4 
2019 - 2023, Federal Subsidy
19 
Postretirement Benefits |
Paid From Qualified Trust
 
Defined Benefit Plan Disclosure [Line Items]
 
2014
61 
2015
63 
2016
66 
2017
69 
2018
72 
2019 - 2023
394 
Postretirement Benefits |
Paid From Company Funds
 
Defined Benefit Plan Disclosure [Line Items]
 
2014
2 
2015
2 
2016
2 
2017
2 
2018
2 
2019 - 2023
$ 12 
Retirement Benefits (Assumptions Used To Determine Net Periodic Benefit Cost) (Details)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Discount rate at measurement date
4.00% 
4.50% 
5.25% 
Expected return on plan assets
7.50% 
7.75% 
8.00% 
Increase in future compensation
3.50% 
3.50% 
3.50% 
Medical cost trend rate (initial)
   
   
0.00% 
Medical cost trend rate (ultimate)
   
   
0.00% 
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Discount rate at measurement date
4.00% 
4.50% 
5.25% 
Expected return on plan assets
7.25% 
7.50% 
7.75% 
Increase in future compensation
3.50% 
3.50% 
3.50% 
Medical cost trend rate (initial)
5.00% 
5.50% 
6.00% 
Medical cost trend rate (ultimate)
5.00% 
5.00% 
5.00% 
Years to ultimate rate
 
1 year 
2 years 
Retirement Benefits (Schedule Of Potential Changes In Key Assumptions) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Pension Benefits
 
Defined Benefit Plan Disclosure [Line Items]
 
Service Cost and Interest Cost, .25% decrease in discount rate
$ (2)
Benefit Obligation, .25% decrease in discount rate
109 
Service Cost and Interest Cost, .25% increase in salary rate
2 
Benefit Obligation, .25% increase in salary rate
17 
Postretirement Benefits
 
Defined Benefit Plan Disclosure [Line Items]
 
Benefit Obligation, .25% decrease in discount rate
32 
Service Cost and Interest Cost, 1.00% increase in annual medical trend
2 
Benefit Obligation, 1.00% increase in annual medical trend
40 
Service Cost and Interest Cost, 1.00% decrease in annual medical trend
(2)
Benefit Obligation, 1.00% decrease in annual medical trend
$ (37)
Retirement Benefits (Schedule Of Matching Contributions) (Details) (401 (K), USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Employer contributions
$ 27 1
$ 26 1
$ 25 1
Union Electric Company
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Employer contributions
16 
16 
16 
Ameren Illinois Company
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Employer contributions
10 
9 
8 
Other
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Employer contributions
$ 1 
$ 1 
$ 1 
Stock-Based Compensation (Narrative) (Details) (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended 1 Months Ended 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Jan. 31, 2013
Performance Share Units
Jan. 31, 2012
Performance Share Units
Dec. 31, 2013
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
 
 
 
 
 
 
Maximum shares available for grants
4,000,000 
 
 
 
 
 
Share-based compensation expense
$ 20 
$ 22 
$ 13 
 
 
 
Employee service share-based compensation, tax benefit from compensation expense
8 
8 
5 
 
 
 
Amounts paid to settle share units
11 
11 
4 
 
 
 
Compensation cost not yet recognized
$ 20 
 
 
 
 
 
Expected weighted average recognition period for share-based compensation expense, in months
20 months 
 
 
 
 
 
Performance period
 
 
 
 
 
3 years 
Percentage of shares issued per share unit, minimum
 
 
 
 
 
0.00% 
Percentage of shares issued per share unit, maximum
 
 
 
 
 
200.00% 
Fair value of each share unit, per share
 
 
 
$ 31.19 
$ 35.68 
$ 31.19 1
Closing common share price
 
 
 
$ 30.72 
$ 33.13 
 
Three-year risk-free rate
 
 
 
0.36% 
0.41% 
 
Volatility rate, minimum
 
 
 
12.00% 
17.00% 
 
Volatility rate, maximum
 
 
 
21.00% 
31.00% 
 
Stock-Based Compensation (Summary Of Nonvested Shares) (Details) (Performance Share Units, USD $)
1 Months Ended 12 Months Ended
Jan. 31, 2013
Jan. 31, 2012
Dec. 31, 2013
Performance Share Units
 
 
 
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
 
 
 
Share Units, Nonvested at beginning of year
1,192,487 
 
1,192,487 
Share Units, Granted
 
 
840,482 1
Share Units, Unearned or forfeited
 
 
(29,730)2
Share Units, Earned and vested
 
 
(784,695)3
Share Units, Nonvested at end of year
 
 
1,218,544 
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
 
 
 
Weighted-average Fair Value per Unit, Nonvested at beginning of year
$ 33.56 
 
$ 33.56 
Weighted-averageFair Value per Unit, granted
$ 31.19 
$ 35.68 
$ 31.19 1
Weighted-average Fair Value per Unit, Unearned or forfeited
 
 
$ 31.93 2
Weighted-average Fair Value per Unit, Earned and vested
 
 
$ 31.60 3
Weighted-average Fair Value per Unit, Nonvested at end of year
 
 
$ 33.23 
Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Income Taxes [Line Items]
 
 
 
Statutory federal income tax rate:
35.00% 
35.00% 
35.00% 
Depreciation differences
   
(1.00%)
(1.00%)
Amortization of investment tax credit
(1.00%)
(1.00%)
(1.00%)
State tax
4.00% 
5.00% 
4.00% 
Other permanent items(a)
 
   
1.00% 
Other permanent items
   
(1.00%)1
 
Tax credits
 
 
(1.00%)
Effective income tax rate
38.00% 
37.00% 
37.00% 
Union Electric Company
 
 
 
Income Taxes [Line Items]
 
 
 
Statutory federal income tax rate:
35.00% 
35.00% 
35.00% 
Depreciation differences
0.00% 
(1.00%)
(2.00%)
Amortization of investment tax credit
(1.00%)
(1.00%)
(1.00%)
State tax
3.00% 
3.00% 
3.00% 
Other permanent items(a)
 
1.00% 
   
Other permanent items
1.00% 1
0.00% 
1.00% 1
Tax credits
 
 
   
Effective income tax rate
38.00% 
37.00% 
36.00% 
Ameren Illinois Company
 
 
 
Income Taxes [Line Items]
 
 
 
Statutory federal income tax rate:
35.00% 
35.00% 
35.00% 
Depreciation differences
(1.00%)
   
   
Amortization of investment tax credit
0.00% 
(1.00%)
(1.00%)
State tax
6.00% 
6.00% 
5.00% 
Other permanent items(a)
 
   
   
Other permanent items
   
   
 
Tax credits
 
 
   
Effective income tax rate
40.00% 
40.00% 
39.00% 
Income Taxes (Schedule Of Components Of Income Tax Expense (Benefit)) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Income Taxes [Line Items]
 
 
 
Current Federal taxes
$ (118)1
$ 40 1
$ (6)1
Current State taxes
19 1
10 1
(2)1
Deferred Federal taxes
368 1
204 1
213 1
Deferred State taxes
48 1
60 1
55 1
Deferred investment tax credits, amortization
(6)1
(7)1
(6)1
Total income tax expense
311 1
307 1
254 1
Union Electric Company
 
 
 
Income Taxes [Line Items]
 
 
 
Current Federal taxes
136 
(25)
3 
Current State taxes
41 
(10)
2 
Deferred Federal taxes
64 
248 
129 
Deferred State taxes
6 
44 
31 
Deferred investment tax credits, amortization
(5)
(5)
(4)
Total income tax expense
242 
252 
161 
Ameren Illinois Company
 
 
 
Income Taxes [Line Items]
 
 
 
Current Federal taxes
(15)
(7)
(24)
Current State taxes
21 
(3)
(4)
Deferred Federal taxes
99 
76 
123 
Deferred State taxes
6 
30 
34 
Deferred investment tax credits, amortization
(1)
(2)
(2)
Total income tax expense
110 
94 
127 
Other Affiliates [Member]
 
 
 
Income Taxes [Line Items]
 
 
 
Current Federal taxes
(239)2
72 
15 
Current State taxes
(43)2
23 
0 
Deferred Federal taxes
205 2
(120)
(39)
Deferred State taxes
36 2
(14)
(10)
Deferred investment tax credits, amortization
0 
0 
0 
Total income tax expense
$ (41)
$ (39)
$ (34)
Income Taxes (Schedule Of Deferred Tax Assets And Liabilities Resulting From Temporary Differences) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Income Taxes [Line Items]
 
 
Plant related
$ 3,769 1
$ 3,550 1
Regulatory assets (liabilities), net
76 1
73 1
Deferred benefit costs
(273)1
(323)1
Purchase accounting
(28)1
(28)1
ARO
(6)1
(6)1
Other
(478)1 2 3
(250)1 2
Total net accumulated deferred income tax liabilities
3,060 1 4
3,016 1 5
Deferred Tax Assets, Valuation Allowance
7 
 
Current assets
106 
170 
Union Electric Company
 
 
Income Taxes [Line Items]
 
 
Plant related
2,513 
2,385 
Regulatory assets (liabilities), net
74 
73 
Deferred benefit costs
(74)
(84)
Purchase accounting
   
   
ARO
(7)
(7)
Other
(17)2
50 2
Total net accumulated deferred income tax liabilities
2,489 4
2,417 5
Deferred Tax Assets, Valuation Allowance
1 
 
Current assets
20 
26 
Ameren Illinois Company
 
 
Income Taxes [Line Items]
 
 
Plant related
1,243 
1,145 
Regulatory assets (liabilities), net
2 
   
Deferred benefit costs
(85)
(102)
Purchase accounting
(27)
(27)
ARO
1 
1 
Other
(63)2
(77)2
Total net accumulated deferred income tax liabilities
1,071 4
940 5
Deferred Tax Assets, Valuation Allowance
1 
 
Current assets
45 
85 
Other Affiliates [Member]
 
 
Income Taxes [Line Items]
 
 
Plant related
13 
20 
Regulatory assets (liabilities), net
   
   
Deferred benefit costs
(114)
(137)
Purchase accounting
(1)
(1)
ARO
0 
0 
Other
(398)2
(223)2
Total net accumulated deferred income tax liabilities
$ (500)4
$ (341)5
Income Taxes (Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
$ 408 1
$ 200 1
Tax credit carryforwards
118 1
109 1
Change in valuation allowance
2 
1 
Federal
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
360 1 2
173 1 3
Tax credit carryforwards
88 1 4
86 1 4
Net operating loss carryforward, expiration period start
Jan. 01, 2028 
Jan. 01, 2028 
Tax credit carryforward, expiration period start
Jan. 01, 2029 
Jan. 01, 2029 
State
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
48 1 5
27 1 6
Tax credit carryforwards
34 1 7
25 1 8
Tax Credit Carryforward, Valuation Allowance
4 1 9
2 1 10
Net operating loss carryforward, expiration period start
Jan. 01, 2017 
Jan. 01, 2017 
Tax credit carryforward, expiration period start
Jan. 01, 2014 
Jan. 01, 2013 
Union Electric Company
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
64 
64 
Tax credit carryforwards
12 
11 
Union Electric Company |
Federal
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
61 2
61 3
Tax credit carryforwards
12 4
11 4
Union Electric Company |
State
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
3 5
3 6
Tax credit carryforwards
1 7
1 8
Tax Credit Carryforward, Valuation Allowance
(1)9
(1)10
Ameren Illinois Company
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
95 
72 
Tax credit carryforwards
   
   
Change in valuation allowance
 
1 
Ameren Illinois Company |
Federal
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
84 2
61 3
Tax credit carryforwards
   
0 4
Ameren Illinois Company |
State
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
11 5
11 6
Tax credit carryforwards
1 7
1 8
Tax Credit Carryforward, Valuation Allowance
(1)9
(1)10
Other Affiliates [Member]
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
249 
64 
Tax credit carryforwards
106 
98 
Other Affiliates [Member] |
Federal
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
215 2
51 3
Tax credit carryforwards
76 4
75 4
Other Affiliates [Member] |
State
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
34 5
13 6
Tax credit carryforwards
32 7
23 8
Tax Credit Carryforward, Valuation Allowance
$ (2)9
$ 0 10
Income Taxes (Reconciliation Of The Change In The Liability For Interest On Unrecognized Tax Benefits) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Income Tax Contingency [Line Items]
 
 
 
Liability for interest
$ 6 1
$ 5 1
$ 17 1
Interest charges (income)
(5)1
1 1
(11)1
Interest payment
 
 
(1)1
Liability for interest
1 1
6 1
5 1
Union Electric Company
 
 
 
Income Tax Contingency [Line Items]
 
 
 
Liability for interest
8 
6 
10 
Interest charges (income)
(8)
2 
(3)
Interest payment
 
 
(1)
Liability for interest
0 
8 
6 
Ameren Illinois Company
 
 
 
Income Tax Contingency [Line Items]
 
 
 
Liability for interest
1 
1 
2 
Interest charges (income)
(1)
0 
(1)
Interest payment
 
 
0 
Liability for interest
0 
1 
1 
Other Affiliates [Member]
 
 
 
Income Tax Contingency [Line Items]
 
 
 
Liability for interest
(3)
(2)
5 
Interest charges (income)
4 
(1)
(7)
Interest payment
 
 
0 
Liability for interest
$ 1 
$ (3)
$ (2)
Income Taxes (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 12 Months Ended 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Jun. 30, 2012
Dec. 31, 2011
Illinois Corporate Income Tax
Jan. 31, 2011
Minimum
Illinois Corporate Income Tax
Jan. 31, 2011
Maximum
Illinois Corporate Income Tax
Dec. 31, 2013
Union Electric Company
Dec. 31, 2012
Union Electric Company
Dec. 31, 2011
Union Electric Company
Jun. 30, 2011
Union Electric Company
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2012
Ameren Illinois Company
Dec. 31, 2011
Ameren Illinois Company
Jun. 30, 2011
Ameren Illinois Company
Dec. 31, 2011
Ameren Illinois Company
Illinois Corporate Income Tax
Dec. 31, 2015
Income Tax Rate in 2015
Illinois Corporate Income Tax
Dec. 31, 2025
Income Tax Rate in 2025
Illinois Corporate Income Tax
Income Taxes [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
State corporate income tax rate
4.00% 
5.00% 
4.00% 
 
 
7.30% 
9.50% 
3.00% 
3.00% 
3.00% 
 
6.00% 
6.00% 
5.00% 
 
 
7.75% 
7.30% 
Increase in current state and local tax expense benefit
 
 
 
 
$ 6 
 
 
 
 
 
 
 
 
 
 
$ 4 
 
 
Decrease in deferred state and local income tax expense benefit
 
 
 
 
2 
 
 
 
 
 
 
 
 
 
 
3 
 
 
Reduction of uncertain tax positions
 
 
 
39 
 
 
 
 
 
 
17 
 
 
 
12 
 
 
 
Estimated Unrecognized Tax Benefits, Decreases Resulting From Settlements with Taxing Authorities
20 
 
 
 
 
 
 
13 
 
 
 
 
 
 
 
 
 
 
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions
$ 103 
 
 
 
 
 
 
$ 95 
 
 
 
$ 5 
 
 
 
 
 
 
Related Party Transactions (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Union Electric Company
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
$ 25 
$ 20 
$ 23 
Operating Expenses
116 
106 
114 
Union Electric Company |
Ameren Missouri Power Supply Agreements with Ameren Illinois
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
3 
1 1
2 
Union Electric Company |
Ameren Missouri and Ameren Illinois Rent and Facility Services
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
21 
19 
16 
Union Electric Company |
Ameren Missouri and Ameren Illinois miscellaneous support services
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
1 
1 
5 
Union Electric Company |
Ameren Illinois Power Supply Agreements with Ameren Missouri
 
 
 
Related Party Transaction [Line Items]
 
 
 
Interest (Charges) Income
 
 
   
Union Electric Company |
Ameren Services Support Services Agreement
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
116 
106 
114 
Union Electric Company |
Insurance Premiums
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
1 1 2
1 1 2
1 1 2
Union Electric Company |
Money Pool
 
 
 
Related Party Transaction [Line Items]
 
 
 
Interest (Charges) Income
1 1
1 1
 
Ameren Illinois Company
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
4 
1 
3 
Operating Expenses
93 
88 
87 
Ameren Illinois Company |
Ameren Missouri and Ameren Illinois Rent and Facility Services
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
1 
1 
2 
Ameren Illinois Company |
Ameren Missouri and Ameren Illinois miscellaneous support services
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
3 
1 1
1 
Ameren Illinois Company |
Ameren Illinois Power Supply Agreements with Ameren Missouri
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
3 
1 1
2 
Interest (Charges) Income
 
 
   
Ameren Illinois Company |
Ameren Illinois transmission agreements with ATXI
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
2 
3 
3 
Ameren Illinois Company |
Purchased Power
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
5 
3 
5 
Ameren Illinois Company |
Ameren Services Support Services Agreement
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
93 
88 
87 
Ameren Illinois Company |
Money Pool
 
 
 
Related Party Transaction [Line Items]
 
 
 
Interest (Charges) Income
$ 1 1
$ 1 1
 
Related Party Transactions (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
1 Months Ended
Apr. 30, 2011
Ameren Illinois Company
Ameren Transmission Company of Illinois
Jan. 31, 2011
Ameren Illinois Company
Ameren Transmission Company of Illinois
Apr. 30, 2012
Period Five
Union Electric Company
May 31, 2011
Period Five
Ameren Illinois Company
Union Electric Company
MWh
Apr. 30, 2012
Period Six
Union Electric Company
May 31, 2011
Period Three
Ameren Illinois Company
Union Electric Company
MWh
Apr. 30, 2010
Period Four
Union Electric Company
May 31, 2011
Period Four
Ameren Illinois Company
Union Electric Company
MWh
Related Party Transaction [Line Items]
 
 
 
 
 
 
 
 
Energy Supply Agreements Amount
 
 
$ 1 
 
$ 3 
 
$ 1 
 
Long-term Contract for Purchase of Electric Power, Related Party Contract, Fixed Power
 
 
 
40,800 
 
16,800 
 
40,800 
Long-term Contract for Purchase of Electric Power, Related Party Contract, Fixed Power, Rate
 
 
 
28 
 
37 
 
29 
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress, Proceeds from Advances to Related Party
 
52 
 
 
 
 
 
 
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress, Proceeds from Advances to Related Party, Accrued Interest
 
3 
 
 
 
 
 
 
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress, Transfers from Related Party
$ 20 
 
 
 
 
 
 
 
Commitments And Contingencies (Callaway Nuclear Energy Center) (Details) (USD $)
12 Months Ended
Dec. 31, 2013
Commitments and Contingencies [Line Items]
 
Insurance aggregate maximum coverage
$ 13,616,000,000 1
Insurance maximum coverage per incident
128,000,000 
Threshold for which a retrospective assessment for a covered loss is necessary
375,000,000 
Annual payment in the event of an incident at any licensed commercial reactor
19,000,000 
Aggregate maximum assessment per incident under Price-Anderson liability provisions of Atomic Energy Act
128,000,000 
Maximum annual payment to be paid in a calendar year per reactor incident under liability provisions of Atomic Energy Act
19,000,000 
Amount of coverage in excess of primary property liability coverage
2,250,000,000.00 
Sub-limit of Amount of Coverage in Excess of Primary Property Liability Coverage for Non-Nuclear Events
1,700,000,000 
Amount of weekly indemnity coverage commencing eight weeks after power outage
4,500,000 
Number of weeks of coverage after the first eight weeks of an outage
P52W 
Amount of additional weekly indemnity coverage commencing after initial indemnity coverage
3,600,000 
Number of additional weeks after initial indemnity coverage for power outage, minimum
P71W 
Amount of weekly indemnity coverage thereafter not exceeding policy limit
490,000,000 
Amount of secondary weekly indemnity coverage for prolonged nuclear plant outage in excess of primary indemnity coverage
900,000 
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period
3,240,000,000 
Public Liability And Nuclear Worker Liability - American Nuclear Insurers
 
Commitments and Contingencies [Line Items]
 
Insurance aggregate maximum coverage
375,000,000 
Insurance maximum coverage per incident
0 
Public Liability And Nuclear Worker Liability - Pool Participation
 
Commitments and Contingencies [Line Items]
 
Insurance aggregate maximum coverage
13,241,000,000 2
Insurance maximum coverage per incident
128,000,000 3
Property Damage - Nuclear Electric Insurance Ltd
 
Commitments and Contingencies [Line Items]
 
Insurance aggregate maximum coverage
2,250,000,000 4
Insurance maximum coverage per incident
23,000,000 5
Sub-limit of Amount of Coverage in Excess of Primary Property Liability Coverage for Non-Nuclear Events
200,000,000 
Replacement Power - Nuclear Electric Insurance Ltd
 
Commitments and Contingencies [Line Items]
 
Insurance aggregate maximum coverage
490,000,000 6
Insurance maximum coverage per incident
9,000,000 5
Sub-limit of Amount of Weekly indemnity Coverage Thereafter Not Exceeding Policy Limit for Non-Nuclear Events
327,600,000 
Replacement Power - Energy Risk Assurance Company
 
Commitments and Contingencies [Line Items]
 
Insurance aggregate maximum coverage
64,000,000 7
Insurance maximum coverage per incident
0 
Property Damage European Mutual Association for Nuclear Insurance
 
Commitments and Contingencies [Line Items]
 
Insurance aggregate maximum coverage
500,000,000 8
Amount of primary property liability coverage
500,000,000 
Property Damage
 
Commitments and Contingencies [Line Items]
 
Insurance aggregate maximum coverage
2,750,000,000 
Insurance maximum coverage per incident
$ 23,000,000 
Commitments And Contingencies (Schedule Of Lease Obligations) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Commitments and Contingencies [Line Items]
 
 
 
Capital lease payments, 2014
$ 32 1 2
 
 
Capital lease payments, 2015
33 1 2
 
 
Capital lease payments, 2016
33 1 2
 
 
Capital lease payments, 2017
33 1 2
 
 
Capital lease payments, 2018
32 1 2
 
 
Capital lease payments, After 5 Years
393 1 2
 
 
Capital lease payments, Total
556 1 2
 
 
Less Amount representing interest, 2014
27 2
 
 
Less Amount representing interest, 2015
27 2
 
 
Less Amount representing interest, 2016
27 2
 
 
Less Amount representing interest, 2017
27 2
 
 
Less Amount representing interest, 2018
26 2
 
 
Less Amount representing interest, After 5 Years
123 2
 
 
Less Amount representing interest, Total
257 2
 
 
Present value of minimum capital lease payments, 2014
5 2
 
 
Present value of minimum capital lease payments, 2015
6 2
 
 
Present value of minimum capital lease payments, 2016
6 2
 
 
Present value of minimum capital lease payments, 2017
6 2
 
 
Present value of minimum capital lease payments, 2018
6 2
 
 
Present value of minimum capital lease payments, After 5 Years
270 2
 
 
Present value of minimum capital lease payments, Total
299 2
 
 
Operating leases, 2014
14 2 3
 
 
Operating leases, 2015
13 2 3
 
 
Operating leases, 2016
13 2 3
 
 
Operating leases, 2017
13 2 3
 
 
Operating leases, 2018
13 2 3
 
 
Operating leases, After 5 Years
51 2 3
 
 
Operating leases, Total
117 2 3
 
 
Total lease obligations, 2014
19 2
 
 
Total lease obligations, 2015
19 2
 
 
Total lease obligations, 2016
19 2
 
 
Total lease obligations, 2017
19 2
 
 
Total lease obligations, 2018
19 2
 
 
Total lease obligations, After 5 Years
321 2
 
 
Total lease obligations, Total
416 2
 
 
Annual obligation for real estate leases and railroad licenses
2 
 
 
Total rental expense
32 4
33 4
36 4
Union Electric Company
 
 
 
Commitments and Contingencies [Line Items]
 
 
 
Capital lease payments, 2014
32 1
 
 
Capital lease payments, 2015
33 1
 
 
Capital lease payments, 2016
33 1
 
 
Capital lease payments, 2017
33 1
 
 
Capital lease payments, 2018
32 1
 
 
Capital lease payments, After 5 Years
393 1
 
 
Capital lease payments, Total
556 1
 
 
Less Amount representing interest, 2014
27 
 
 
Less Amount representing interest, 2015
27 
 
 
Less Amount representing interest, 2016
27 
 
 
Less Amount representing interest, 2017
27 
 
 
Less Amount representing interest, 2018
26 
 
 
Less Amount representing interest, After 5 Years
123 
 
 
Less Amount representing interest, Total
257 
 
 
Present value of minimum capital lease payments, 2014
5 
 
 
Present value of minimum capital lease payments, 2015
6 
 
 
Present value of minimum capital lease payments, 2016
6 
 
 
Present value of minimum capital lease payments, 2017
6 
 
 
Present value of minimum capital lease payments, 2018
6 
 
 
Present value of minimum capital lease payments, After 5 Years
270 
 
 
Present value of minimum capital lease payments, Total
299 
 
 
Operating leases, 2014
11 3
 
 
Operating leases, 2015
11 3
 
 
Operating leases, 2016
11 3
 
 
Operating leases, 2017
12 3
 
 
Operating leases, 2018
11 3
 
 
Operating leases, After 5 Years
50 3
 
 
Operating leases, Total
106 3
 
 
Total lease obligations, 2014
16 
 
 
Total lease obligations, 2015
17 
 
 
Total lease obligations, 2016
17 
 
 
Total lease obligations, 2017
18 
 
 
Total lease obligations, 2018
17 
 
 
Total lease obligations, After 5 Years
320 
 
 
Total lease obligations, Total
405 
 
 
Annual obligation for real estate leases and railroad licenses
1 
 
 
Total rental expense
29 
29 
29 
Ameren Illinois Company
 
 
 
Commitments and Contingencies [Line Items]
 
 
 
Operating leases, 2014
2 3
 
 
Operating leases, 2015
1 3
 
 
Operating leases, 2016
1 3
 
 
Operating leases, 2017
1 3
 
 
Operating leases, 2018
1 3
 
 
Operating leases, After 5 Years
1 3
 
 
Operating leases, Total
7 3
 
 
Annual obligation for real estate leases and railroad licenses
1 
 
 
Total rental expense
$ 21 
$ 19 
$ 17 
Commitments And Contingencies (Schedule Of Estimated Purchased Power Commitments) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2013
Coal
Dec. 31, 2013
Natural Gas
Dec. 31, 2013
Nuclear Fuel
Dec. 31, 2013
Purchased Power
Dec. 31, 2013
Methane Gas
Dec. 31, 2013
Other
Dec. 31, 2013
Union Electric Company
Dec. 31, 2013
Union Electric Company
Coal
Dec. 31, 2013
Union Electric Company
Natural Gas
Dec. 31, 2013
Union Electric Company
Nuclear Fuel
Dec. 31, 2013
Union Electric Company
Purchased Power
Dec. 31, 2013
Union Electric Company
Methane Gas
Dec. 31, 2013
Union Electric Company
Other
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Coal
Dec. 31, 2013
Ameren Illinois Company
Natural Gas
Dec. 31, 2013
Ameren Illinois Company
Nuclear Fuel
Dec. 31, 2013
Ameren Illinois Company
Purchased Power
Dec. 31, 2013
Ameren Illinois Company
Methane Gas
Dec. 31, 2013
Ameren Illinois Company
Other
Dec. 31, 2015
Investment in Energy Efficiency Programs
Union Electric Company
Dec. 31, 2014
Investment in Energy Efficiency Programs
Union Electric Company
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2014
$ 1,519 1
$ 620 1
$ 323 1
$ 64 1
$ 308 1 2
$ 3 1
$ 201 1
$ 895 
$ 620 
$ 62 
$ 64 
$ 19 2
$ 3 
$ 127 
$ 573 
    
$ 261 
    
$ 289 2
    
$ 23 
 
$ 48 
2015
1,195 1
642 1
179 1
63 1
164 1 2
4 1
143 1
861 
642 
32 
63 
19 2
4 
101 
316 
   
147 
   
145 2
   
24 
64 
 
2016
993 1
664 1
90 1
81 1
78 1 2
4 1
76 1
827 
664 
19 
81 
19 2
4 
40 
154 
   
71 
   
59 2
   
24 
 
 
2017
888 1
676 1
45 1
58 1
55 1 2
4 1
50 1
794 
676 
11 
58 
19 2
4 
26 
94 
   
34 
   
36 2
   
24 
 
 
2018
313 1
120 1
28 1
57 1
52 1 2
5 1
51 1
236 
120 
8 
57 
19 2
5 
27 
77 
   
20 
   
33 2
   
24 
 
 
Thereafter
1,441 1
125 1
82 1
158 1
635 1 2
91 1
350 1
695 
125 
28 
158 
110 2
91 
183 
746 
   
54 
   
525 2
   
167 
 
 
Total
$ 6,349 1
$ 2,847 1
$ 747 1
$ 481 1
$ 1,292 1 2
$ 111 1
$ 871 1
$ 4,308 
$ 2,847 
$ 160 
$ 481 
$ 205 2
$ 111 
$ 504 
$ 1,960 
    
$ 587 
    
$ 1,087 2
    
$ 286 
 
 
Renewable Energy Credits Agreements, Term
 
 
 
 
20 years 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Commitments And Contingencies (Environmental Matters) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Manufactured Gas Plant
 
Loss contingency range of possible loss, minimum
$ 278.0 
Loss contingency range of possible loss, maximum
338.0 
Accrual for environmental loss contingencies
278.0 1
Manufactured Gas Plant |
Union Electric Company
 
Loss contingency range of possible loss, minimum
4.0 
Loss contingency range of possible loss, maximum
5.0 
Accrual for environmental loss contingencies
4.0 1
Manufactured Gas Plant |
Ameren Illinois Company
 
Number of remediation sites
44 
Loss contingency range of possible loss, minimum
274.0 
Loss contingency range of possible loss, maximum
333.0 
Accrual for environmental loss contingencies
274.0 1
Former Coal Ash Landfill |
Ameren Illinois Company
 
Loss contingency range of possible loss, minimum
0.5 
Loss contingency range of possible loss, maximum
6.0 
Accrual for environmental loss contingencies
0.5 
Other Environmental |
Ameren Illinois Company
 
Accrual for environmental loss contingencies
0.8 
Former Coal Tar Distillery |
Union Electric Company
 
Loss contingency range of possible loss, minimum
2.0 
Loss contingency range of possible loss, maximum
5.0 
Accrual for environmental loss contingencies
2.0 
Sauget Area 2 |
Union Electric Company
 
Loss contingency range of possible loss, minimum
0.3 
Loss contingency range of possible loss, maximum
10.0 
Accrual for environmental loss contingencies
0.3 
Substation in St Charles, Missouri |
Union Electric Company
 
Loss contingency range of possible loss, minimum
1.6 
Loss contingency range of possible loss, maximum
4.5 
Accrual for environmental loss contingencies
1.6 
Minimum
 
Estimated capital costs to comply with existing and known federal and state air emissions regulations
275 
Maximum
 
Estimated capital costs to comply with existing and known federal and state air emissions regulations
$ 350 
Commitments And Contingencies (Pumped-Storage Hydroelectric Facility Breach) (Details) (Union Electric Company, USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Union Electric Company
 
Commitments and Contingencies [Line Items]
 
Insurance Settlements Receivable
$ 68 
Divestiture Transactions and Discontinued Operations (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
1 Months Ended 0 Months Ended 1 Months Ended 12 Months Ended 3 Months Ended 12 Months Ended 3 Months Ended 1 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Shutdown Of Meredosia And Hutsonville Energy Centers [Member]
Dec. 31, 2013
Shutdown Of Meredosia And Hutsonville Energy Centers [Member]
Dec. 31, 2012
Shutdown Of Meredosia And Hutsonville Energy Centers [Member]
Mar. 14, 2013
New Ameren Energy Resources Company, LLC
Jan. 31, 2014
New Ameren Energy Resources Company, LLC
Dec. 31, 2013
New Ameren Energy Resources Company, LLC
Dec. 31, 2013
Notes Payable, Other Payables
New Ameren Energy Resources Company, LLC
Dec. 31, 2013
Elgin, Gibson City and Grand Tower Energy Centers
Dec. 31, 2013
Merchant Generation
Dec. 31, 2012
Merchant Generation
Mar. 31, 2012
Merchant Generation
Duck Creek Energy Center
Dec. 31, 2013
Ameren Energy Marketing Company
Dec. 31, 2013
Guarantee Type, Other [Member]
Jan. 31, 2014
Subsequent Event
Elgin, Gibson City and Grand Tower Energy Centers
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Asset retirement obligations
$ 369 
$ 349 
 
$ 31 
$ 26 
 
 
 
 
 
 
 
 
 
 
 
Disposal Group, Including Discontinued Operation, Working Capital Adjustment, Period
 
 
 
 
 
 
120 days 
 
 
 
 
 
 
 
 
 
Converted instrument, period for conversion
 
 
 
 
 
 
 
 
24 months 
 
 
 
 
 
 
 
Notes, Loans and Financing Receivable, Net, Noncurrent
 
 
 
 
 
 
 
 
18 
 
 
 
 
 
 
 
Transaction agreement, cash retained by counterparty
 
 
 
 
 
235 
 
 
 
 
 
 
 
 
 
 
Obligation to provide credit support, period
 
 
 
 
 
24 months 
 
 
 
 
 
 
 
 
 
 
Buyer's indemnification guarantee obligation
 
 
 
 
 
25 
 
 
 
 
 
 
 
 
 
 
Buyer's indemnification guarantee obligation, period
 
 
 
 
 
24 months 
 
 
 
 
 
 
 
 
 
 
Impairment of assets to be disposed of
 
 
 
 
 
 
 
 
 
 
201 
1,950 
628 
 
 
 
Disposal group, fair value
 
 
 
 
 
 
 
 
 
137.5 
 
 
 
 
 
 
Discontinued operations deferred tax expense
 
 
 
 
 
 
 
 
 
 
99 
 
 
 
 
 
Discontinued operations deferred tax benefit
 
 
 
 
 
 
 
 
 
 
86 
 
 
 
 
 
Related Party Transaction, Guarantees Outstanding
190 
 
 
 
 
 
 
 
 
 
 
 
 
176 
14 
 
Related Party Transaction, Guarantees, Maximum Exposure
 
 
 
 
 
 
 
 
 
 
 
 
 
6 
 
 
Letters of Credit Outstanding, Amount
11 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Loss contingency range of possible loss, maximum
 
 
 
 
 
 
 
39.0 
 
 
 
 
 
 
 
 
Other deferred credits and liabilities
622 
643 
 
 
 
 
 
29 
 
 
 
 
 
 
 
 
Accounts Payable and Accrued Liabilities, Current
806 
533 
 
 
 
 
 
10 
 
 
 
 
 
 
 
 
Proceeds from Sales of Business, Affiliate and Productive Assets
 
 
 
 
 
 
 
 
 
137.5 
 
 
 
 
 
168.0 
Impairment of Long-Lived Assets Held-for-use
 
 
26 
 
 
 
 
 
 
 
 
 
 
 
 
 
Inventory Write-down
 
 
4 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceeds from Asset Sale Held in Escrow
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
$ 17 
Divestiture Transactions and Discontinued Operations (Components of Discontinued Operations in Consolidated Statement of Income) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended 3 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2013
Merchant Generation
Dec. 31, 2012
Merchant Generation
Mar. 31, 2012
Merchant Generation
Duck Creek Energy Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
 
 
 
 
Operating revenues
$ 1,037 
$ 1,047 
$ 1,358 
 
 
 
Operating expenses
(1,207)1
(3,474)2
(1,150)
 
 
 
Operating income (loss)
(170)
(2,427)
208 
 
 
 
Other income (loss)
(1)
   
1 
 
 
 
Interest charges
(39)
(56)
(64)
 
 
 
Income (loss) before income taxes
(210)
(2,483)
145 
 
 
 
Income tax (expense) benefit
(13)
987 
(56)
 
 
 
Income (Loss) from Discontinued Operations, Net of Tax (Note 16)
(223)
(1,496)
89 
 
 
 
Impairment of assets to be disposed of
 
 
 
$ 201 
$ 1,950 
$ 628 
Divestiture Transactions and Discontinued Operations (Components of Assets and Liabilities on Consolidated Balance Sheet) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
 
Asset retirement obligations
$ 369 
$ 349 
 
Current assets of discontinued operations
 
 
 
Cash and cash equivalents
   
25 
7 
Accounts receivable and unbilled revenue
5 
102 
 
Materials and supplies
5 
135 
 
Mark-to-market derivative assets
   
102 
 
Property and plant, net
142 
748 
 
Accumulated deferred income taxes, net
13 1
395 1
 
Other assets
   
104 
 
Total current assets of discontinued operations
165 
1,611 
3,721 
Current liabilities of discontinued operations
 
 
 
Accounts payable and other current obligations
5 
141 
 
Mark-to-market derivative liabilities
   
63 
 
Long-term debt, net
   
824 
 
Asset retirement obligations
40 2
97 2
 
Pension and other postretirement benefits
   
40 
 
Other liabilities
   
28 
 
Total current liabilities of discontinued operations
45 
1,193 
 
Accumulated other comprehensive income (loss)
   3
19 3
 
Noncontrolling Interest
   4
8 4
 
Electric Energy Inc
 
 
 
Current liabilities of discontinued operations
 
 
 
Percentage of EEI not owned by Ameren
 
20.00% 
 
Shutdown Of Meredosia And Hutsonville Energy Centers [Member]
 
 
 
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
 
Asset retirement obligations
$ 31 
$ 26 
 
Segment Information (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2013
segment
Dec. 31, 2012
Dec. 31, 2011
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Assets of discontinued operations (Note 16)
$ 165 
 
 
 
$ 1,611 
 
 
 
$ 165 
$ 1,611 
$ 3,721 
Number of reportable segments
 
 
 
 
 
 
 
 
2 
 
 
External revenues
1,322 
1,638 
1,403 
1,475 
1,258 
1,709 
1,402 
1,412 
5,838 
5,781 
6,148 
Depreciation and amortization
 
 
 
 
 
 
 
 
706 
673 
643 
Interest Expense
 
 
 
 
 
 
 
 
398 
392 
387 
Income taxes (benefit)
 
 
 
 
 
 
 
 
311 1
307 1
254 1
Net income (loss) attributable to Ameren Corporation
37 
302 
95 
(145)
(1,156)
374 
211 
(403)
289 
(974)
519 
Income (Loss) from Continuing Operations Attributable to Parent
48 
305 
105 
54 
12 
302 
164 
38 
512 
516 
431 
Capital expenditures
 
 
 
 
 
 
 
 
1,379 
1,063 
881 
Total assets
21,042 
 
 
 
22,230 
 
 
 
21,042 
22,230 
 
Union Electric Company
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
 
 
 
 
 
 
 
 
3,516 
3,252 
3,360 
Revenue from Related Parties
 
 
 
 
 
 
 
 
25 
20 
23 
Depreciation and amortization
 
 
 
 
 
 
 
 
454 
440 
408 
Interest and dividend income
 
 
 
 
 
 
 
 
27 
32 
30 
Interest Expense
 
 
 
 
 
 
 
 
210 
223 
209 
Income taxes (benefit)
 
 
 
 
 
 
 
 
242 
252 
161 
Net income (loss) attributable to Ameren Corporation
 
 
 
 
 
 
 
 
395 
416 
287 
Capital expenditures
 
 
 
 
 
 
 
 
648 
595 
550 
Total assets
12,904 
 
 
 
13,043 
 
 
 
12,904 
13,043 
12,757 
Ameren Illinois Company
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
 
 
 
 
 
 
 
 
2,307 
2,524 
2,784 
Revenue from Related Parties
 
 
 
 
 
 
 
 
4 
1 
3 
Depreciation and amortization
 
 
 
 
 
 
 
 
243 
221 
215 
Interest and dividend income
 
 
 
 
 
 
 
 
2 
0 
1 
Interest Expense
 
 
 
 
 
 
 
 
143 
129 
136 
Income taxes (benefit)
 
 
 
 
 
 
 
 
110 
94 
127 
Net income (loss) attributable to Ameren Corporation
 
 
 
 
 
 
 
 
160 
141 
193 
Capital expenditures
 
 
 
 
 
 
 
 
701 
442 
351 
Total assets
7,454 
 
 
 
7,282 
 
 
 
7,454 
7,282 
7,213 
Other Segment
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
 
 
 
 
 
 
 
 
15 
5 
4 
Revenue from Related Parties
 
 
 
 
 
 
 
 
2 
3 
3 
Depreciation and amortization
 
 
 
 
 
 
 
 
9 
12 
20 
Interest and dividend income
 
 
 
 
 
 
 
 
1 
   
   
Interest Expense
 
 
 
 
 
 
 
 
45 
40 
42 
Income taxes (benefit)
 
 
 
 
 
 
 
 
(41)
(39)
(34)
Net income (loss) attributable to Ameren Corporation
 
 
 
 
 
 
 
 
(43)
(41)
(49)
Capital expenditures
 
 
 
 
 
 
 
 
30 2
26 2
(20)2
Total assets
752 
 
 
 
1,228 
 
 
 
752 
1,228 
1,211 
Intersegment Elimination
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Revenue from Related Parties
 
 
 
 
 
 
 
 
(31)
(24)
(29)
Interest and dividend income
 
 
 
 
 
 
 
 
   
   
   
Interest Expense
 
 
 
 
 
 
 
 
   
   
   
Total assets
(233)
 
 
 
(934)
 
 
 
(233)
(934)
(1,179)
Segment, Continuing Operations
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
 
 
 
 
 
 
 
 
5,838 
5,781 
6,148 
Depreciation and amortization
 
 
 
 
 
 
 
 
706 
673 
643 
Interest and dividend income
 
 
 
 
 
 
 
 
30 
32 
31 
Interest Expense
 
 
 
 
 
 
 
 
398 
392 
387 
Income taxes (benefit)
 
 
 
 
 
 
 
 
311 
307 
254 
Income (Loss) from Continuing Operations Attributable to Parent
 
 
 
 
 
 
 
 
512 
516 
431 
Capital expenditures
 
 
 
 
 
 
 
 
1,379 
1,063 
881 
Total assets
20,877 3
 
 
 
20,619 3
 
 
 
20,877 3
20,619 3
20,002 3
Union Electric Company
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
763 
1,093 
889 
796 
673 
1,064 
844 
691 
3,541 
3,272 
3,383 
Revenue from Related Parties
 
 
 
 
 
 
 
 
25 
20 
23 
Depreciation and amortization
 
 
 
 
 
 
 
 
454 
440 
408 
Interest Expense
 
 
 
 
 
 
 
 
210 
223 
209 
Income taxes (benefit)
 
 
 
 
 
 
 
 
242 
252 
161 
Net income (loss) attributable to Ameren Corporation
33 
239 
85 
41 
16 
237 
144 
22 
398 
419 
290 
Capital expenditures
 
 
 
 
 
 
 
 
648 
595 
550 
Total assets
12,904 
 
 
 
13,043 
 
 
 
12,904 
13,043 
 
Ameren Illinois Company
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
564 
547 
516 
684 
589 
648 
564 
724 
2,311 
2,525 
2,787 
Revenue from Related Parties
 
 
 
 
 
 
 
 
4 
1 
3 
Depreciation and amortization
 
 
 
 
 
 
 
 
243 
221 
215 
Interest Expense
 
 
 
 
 
 
 
 
143 
129 
136 
Income taxes (benefit)
 
 
 
 
 
 
 
 
110 
94 
127 
Net income (loss) attributable to Ameren Corporation
22 
77 
32 
32 
12 
71 
33 
28 
163 
144 
196 
Capital expenditures
 
 
 
 
 
 
 
 
701 
442 
351 
Total assets
$ 7,454 
 
 
 
$ 7,282 
 
 
 
$ 7,454 
$ 7,282 
 
Selected Quarterly Information (Summary Of Selected Quarterly Information) (Details) (USD $)
3 Months Ended 12 Months Ended
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Selected Quarterly Financial Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
$ 1,322,000,000 
$ 1,638,000,000 
$ 1,403,000,000 
$ 1,475,000,000 
$ 1,258,000,000 
$ 1,709,000,000 
$ 1,402,000,000 
$ 1,412,000,000 
$ 5,838,000,000 
$ 5,781,000,000 
$ 6,148,000,000 
Operating Income
171,000,000 
567,000,000 
261,000,000 
185,000,000 
112,000,000 
570,000,000 
347,000,000 
159,000,000 
1,184,000,000 
1,188,000,000 
1,033,000,000 
Net income (loss)
38,000,000 
304,000,000 
96,000,000 
(143,000,000)
(1,155,000,000)
374,000,000 
210,000,000 
(403,000,000)
295,000,000 
(974,000,000)
526,000,000 
Net income attributable to Ameren Corporation - continuing operations
48,000,000 
305,000,000 
105,000,000 
54,000,000 
12,000,000 
302,000,000 
164,000,000 
38,000,000 
512,000,000 
516,000,000 
431,000,000 
Net income (loss) attributable to Ameren Corporation - discontinued operations
(11,000,000)
(3,000,000)
(10,000,000)
(199,000,000)
(1,168,000,000)
72,000,000 
47,000,000 
(441,000,000)
223,000,000 
1,490,000,000 
(88,000,000)
Net income (loss) attributable to Ameren Corporation
37,000,000 
302,000,000 
95,000,000 
(145,000,000)
(1,156,000,000)
374,000,000 
211,000,000 
(403,000,000)
289,000,000 
(974,000,000)
519,000,000 
Impairment and other charges
 
 
 
 
 
 
 
 
   
   
 
Earnings per common share - basic - continuing operations
$ 0.19 
$ 1.26 
$ 0.44 
$ 0.22 
$ 0.05 
$ 1.25 
$ 0.67 
$ 0.16 
$ 2.11 
$ 2.13 
$ 1.79 
Earnings (loss) per common share - basic - discontinued operations
$ (0.04)
$ (0.01)
$ (0.05)
$ (0.82)
$ (4.81)
$ 0.29 
$ 0.20 
$ (1.82)
$ (0.92)
$ (6.14)
$ 0.36 
Earnings (loss) per common share - basic
$ 0.15 
$ 1.25 
$ 0.39 
$ (0.60)
$ (4.76)
$ 1.54 
$ 0.87 
$ (1.66)
$ 1.19 
$ (4.01)
$ 2.15 
Earnings per common share - diluted - continuing operations
$ 0.19 
$ 1.25 
$ 0.44 
$ 0.22 
$ 0.05 
$ 1.25 
$ 0.67 
$ 0.16 
$ 2.10 
$ 2.13 
$ 1.79 
Earnings (loss) per common share - diluted - discontinued operations
$ (0.04)
$ (0.01)
$ (0.05)
$ (0.82)
$ (4.81)
$ 0.29 
$ 0.20 
$ (1.82)
$ (0.92)
$ (6.14)
$ 0.36 
Earnings (loss) per common share - diluted
$ 0.15 
$ 1.24 
$ 0.39 
$ (0.60)
$ (4.76)
$ 1.54 
$ 0.87 
$ (1.66)
$ 1.18 
$ (4.01)
$ 2.15 
Union Electric Company
 
 
 
 
 
 
 
 
 
 
 
Selected Quarterly Financial Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
763,000,000 
1,093,000,000 
889,000,000 
796,000,000 
673,000,000 
1,064,000,000 
844,000,000 
691,000,000 
3,541,000,000 
3,272,000,000 
3,383,000,000 
Operating Income
96,000,000 
417,000,000 
179,000,000 
111,000,000 
69,000,000 
429,000,000 
269,000,000 
78,000,000 
803,000,000 
845,000,000 
609,000,000 
Net income (loss)
 
 
 
 
 
 
 
 
398,000,000 
419,000,000 
290,000,000 
Net income (loss) attributable to Ameren Corporation
33,000,000 
239,000,000 
85,000,000 
41,000,000 
16,000,000 
237,000,000 
144,000,000 
22,000,000 
398,000,000 
419,000,000 
290,000,000 
Net Income Available to Common Stockholder
33,000,000 
238,000,000 
84,000,000 
40,000,000 
16,000,000 
236,000,000 
143,000,000 
21,000,000 
395,000,000 
416,000,000 
287,000,000 
Ameren Illinois Company
 
 
 
 
 
 
 
 
 
 
 
Selected Quarterly Financial Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
564,000,000 
547,000,000 
516,000,000 
684,000,000 
589,000,000 
648,000,000 
564,000,000 
724,000,000 
2,311,000,000 
2,525,000,000 
2,787,000,000 
Operating Income
85,000,000 
158,000,000 
87,000,000 
85,000,000 
51,000,000 
151,000,000 
86,000,000 
89,000,000 
415,000,000 
377,000,000 
458,000,000 
Net income (loss)
 
 
 
 
 
 
 
 
163,000,000 
144,000,000 
196,000,000 
Net income (loss) attributable to Ameren Corporation
22,000,000 
77,000,000 
32,000,000 
32,000,000 
12,000,000 
71,000,000 
33,000,000 
28,000,000 
163,000,000 
144,000,000 
196,000,000 
Net Income Available to Common Stockholder
21,000,000 
77,000,000 
31,000,000 
31,000,000 
11,000,000 
71,000,000 
32,000,000 
27,000,000 
160,000,000 
141,000,000 
193,000,000 
Merchant Generation
 
 
 
 
 
 
 
 
 
 
 
Selected Quarterly Financial Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Impairment and other charges
 
 
 
 
 
 
 
 
 
$ 2,600,000,000 
 
Schedule I - Condensed Financial Information Of Parent (Statement of Income) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2012
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
$ 1,322 
$ 1,638 
$ 1,403 
$ 1,475 
$ 1,258 
$ 1,709 
$ 1,402 
$ 1,412 
$ 5,838 
$ 5,781 
$ 6,148 
Operating expenses
 
 
 
 
 
 
 
 
4,654 
4,593 
5,115 
Operating Income
171 
567 
261 
185 
112 
570 
347 
159 
1,184 
1,188 
1,033 
Interest income from affiliates
 
 
 
 
 
 
 
 
3 1
4 1 2
3 1
Miscellaneous expense
 
 
 
 
 
 
 
 
26 1
37 1
23 1
Interest charges
 
 
 
 
 
 
 
 
398 
392 
387 
Income taxes (benefit)
 
 
 
 
 
 
 
 
311 1
307 1
254 1
Net income attributable to Ameren Corporation - continuing operations
48 
305 
105 
54 
12 
302 
164 
38 
512 
516 
431 
Net Income (Loss) Attributable to Ameren Corporation - Discontinued Operations
11 
3 
10 
199 
1,168 
(72)
(47)
441 
(223)
(1,490)
88 
Net income (loss) attributable to Ameren Corporation
37 
302 
95 
(145)
(1,156)
374 
211 
(403)
289 
(974)
519 
Comprehensive Income from Continuing Operations
 
 
 
 
 
 
 
 
 
 
 
Pension and other postretirement activity, net of income taxes (benefit)
 
 
 
 
 
 
 
 
30 
(8)
(19)
Comprehensive Income (Loss) from Continuing Operations, Net of Tax, Portion Attributable to Parent
 
 
 
 
 
 
 
 
542 
508 
412 
Other Comprehensive Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
 
 
 
 
 
 
 
 
(18)
58 
(20)
Comprehensive Income (Loss) from Discontinued Operations
 
 
 
 
 
 
 
 
(242)
(1,440)
74 
Comprehensive Income (Loss) Attributable to Ameren Corporation
 
 
 
 
 
 
 
 
300 
(932)
486 
Other Comprehensive Income (Loss), Taxes:
 
 
 
 
 
 
 
 
 
 
 
Pension and other postretirement activity, tax (benefit)
 
 
 
 
 
 
 
 
16 
(6)
(14)
Parent Company
 
 
 
 
 
 
 
 
 
 
 
Condensed Financial Statements, Captions [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
 
 
 
 
 
 
 
 
   
   
   
Operating expenses
 
 
 
 
 
 
 
 
26 
17 
13 
Operating Income
 
 
 
 
 
 
 
 
(26)
(17)
(13)
Equity in earnings of subsidiaries
 
 
 
 
 
 
 
 
546 
546 
464 
Interest income from affiliates
 
 
 
 
 
 
 
 
3 
3 
5 
Miscellaneous expense
 
 
 
 
 
 
 
 
5 
4 
4 
Interest charges
 
 
 
 
 
 
 
 
42 
39 
41 
Income taxes (benefit)
 
 
 
 
 
 
 
 
(36)
(27)
(20)
Net income attributable to Ameren Corporation - continuing operations
 
 
 
 
 
 
 
 
512 
516 
431 
Net Income (Loss) Attributable to Ameren Corporation - Discontinued Operations
 
 
 
 
 
 
 
 
(223)
(1,490)
88 
Net income (loss) attributable to Ameren Corporation
 
 
 
 
 
 
 
 
289 
(974)
519 
Comprehensive Income from Continuing Operations
 
 
 
 
 
 
 
 
 
 
 
Pension and other postretirement activity, net of income taxes (benefit)
 
 
 
 
 
 
 
 
30 
(8)
(19)
Comprehensive Income (Loss) from Continuing Operations, Net of Tax, Portion Attributable to Parent
 
 
 
 
 
 
 
 
542 
508 
412 
Other Comprehensive Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
 
 
 
 
 
 
 
 
(19)
50 
(14)
Comprehensive Income (Loss) from Discontinued Operations
 
 
 
 
 
 
 
 
(242)
(1,440)
74 
Comprehensive Income (Loss) Attributable to Ameren Corporation
 
 
 
 
 
 
 
 
300 
(932)
486 
Other Comprehensive Income (Loss), Taxes:
 
 
 
 
 
 
 
 
 
 
 
Pension and other postretirement activity, tax (benefit)
 
 
 
 
 
 
 
 
$ 16 
$ (6)
$ (14)
Schedule I - Condensed Financial Information Of Parent (Balance Sheet) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
ASSETS
 
 
 
 
Cash and cash equivalents
$ 30 
$ 184 
$ 248 
 
Accounts and notes receivable - affiliates
404 
354 
 
 
Miscellaneous accounts and notes receivable
196 
71 
 
 
Other current assets
85 
98 
 
 
Total current assets
1,972 
3,596 
 
 
Current accumulated deferred income taxes, net
106 
170 
 
 
Other non-current assets
698 
667 
 
 
TOTAL ASSETS
21,042 
22,230 
 
 
LIABILITIES AND EQUITY
 
 
 
 
Current maturities of long-term debt
534 
355 
 
 
Short-term debt
368 
   
 
 
Accounts Payable and Accrued Liabilities, Current
806 
533 
 
 
Other current liabilities
194 
168 
 
 
Total current liabilities
2,461 
2,686 
 
 
Long-term debt
5,504 
5,802 
 
 
Other deferred credits and liabilities
622 
643 
 
 
Commitments and Contingencies
   
   
 
 
Retained earnings
907 
1,006 
 
 
Accumulated other comprehensive income (loss)
3 
(8)
 
 
Total equity
6,686 
6,767 
8,068 
 
TOTAL LIABILITIES AND EQUITY
21,042 
22,230 
 
 
Parent Company
 
 
 
 
ASSETS
 
 
 
 
Cash and cash equivalents
11 
23 
3 
4 
Advances to money pool
334 
316 
 
 
Accounts and notes receivable - affiliates
27 
31 
 
 
Miscellaneous accounts and notes receivable
125 
   
 
 
Other current assets
42 
49 
 
 
Total current assets
539 
419 
 
 
Investments in subsidiaries - continuing operations
6,336 
6,315 
 
 
Investments in subsidiaries - discontinued operations
(5)
(353)
 
 
Note receivable - affiliates
51 
462 
 
 
Current accumulated deferred income taxes, net
623 
210 
 
 
Other non-current assets
141 
110 
 
 
TOTAL ASSETS
7,685 
7,163 
 
 
LIABILITIES AND EQUITY
 
 
 
 
Current maturities of long-term debt
425 
   
 
 
Short-term debt
368 
   
 
 
Accounts Payable and Accrued Liabilities, Current
119 
3 
 
 
Accounts payable – affiliates
4 
10 
 
 
Other current liabilities
20 
30 
 
 
Total current liabilities
936 
43 
 
 
Long-term debt
   
424 
 
 
Other deferred credits and liabilities
205 
80 
 
 
Total liabilities
1,141 
547 
 
 
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 242.6
2 
2 
 
 
Other paid-in capital, principally premium on common stock
5,632 
5,616 
 
 
Retained earnings
907 
1,006 
 
 
Accumulated other comprehensive income (loss)
3 
(8)
 
 
Total equity
6,544 
6,616 
 
 
TOTAL LIABILITIES AND EQUITY
$ 7,685 
$ 7,163 
 
 
Schedule I - Condensed Financial Information Of Parent (Statement of Cash Flows) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
 
 
 
Net cash provided by operating activities
$ 1,693 
$ 1,690 
$ 1,878 
Cash Flows From Investing Activities:
 
 
 
Other
2 
2 
15 
Net cash used in investing activities
(1,723)
(1,310)
(1,048)
Cash flows from financing activities:
 
 
 
Dividends on common stock
(388)
(382)
(375)
Short-term debt and credit facility borrowings, net
368 
(148)
(481)
Issuances:
 
 
 
Long-term debt
278 
882 
   
Common stock
   
   
65 
Net cash provided by (used in) financing activities
(149)
(426)
(1,120)
Net change in cash and cash equivalents
(179)
(46)
(290)
Cash and cash equivalents at beginning of year
184 
248 
 
Cash and cash equivalents at end of year
30 
184 
248 
Noncash financing activity – dividends on common stock
   
7 
   
Parent Company
 
 
 
Condensed Financial Statements, Captions [Line Items]
 
 
 
Net cash provided by operating activities
453 
532 
804 
Cash Flows From Investing Activities:
 
 
 
Money pool advances, net
(371)
24 
(276)
Intercompany notes receivable, net
(23)
(20)
358 
Investments in subsidiaries
(50)
(2)
(94)
Return of investments
1 
21 
3 
Other
(2)
(5)
(5)
Net cash used in investing activities
(445)
18 
(14)
Cash flows from financing activities:
 
 
 
Dividends on common stock
(388)
(382)
(375)
Short-term debt and credit facility borrowings, net
368 
(148)
(481)
Issuances:
 
 
 
Common stock
   
   
65 
Net cash provided by (used in) financing activities
(20)
(530)
(791)
Net change in cash and cash equivalents
(12)
20 
(1)
Cash and cash equivalents at beginning of year
23 
3 
4 
Cash and cash equivalents at end of year
11 
23 
3 
Cash dividends received from consolidated subsidiaries
570 
610 
730 
Noncash investing activity - divestiture
494 
 
 
Noncash financing activity – dividends on common stock
    
$ (7)
    
Schedule I - Condensed Financial Information Of Parent (Impairment and Other Charges) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended 1 Months Ended
Dec. 31, 2013
Parent Company
Merchant Generation
Dec. 31, 2012
Parent Company
Merchant Generation
Jan. 31, 2014
New Ameren Energy Resources Company, LLC
Impairment and Other Charges [Line Items]
 
 
 
Impairment charge on long-lived assets and related charges
$ 201 
$ 1,880 
 
Disposal Group, Including Discontinued Operation, Working Capital Adjustment, Period
 
 
120 days 
Schedule II - Valuation And Qualifying Accounts (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Allowance For Doubtful Accounts
 
 
 
Valuation and Qualifying Accounts Disclosure [Line Items]
 
 
 
Balance at Beginning of Period
$ 17 
$ 20 
$ 23 
Charged to Costs and Expenses
35 
30 
41 
Charged to Other Accounts
4 1
2 1
   1
Deductions
38 2
35 2
44 2
Balance at End of Period
18 
17 
20 
Valuation Allowance of Deferred Tax Assets
 
 
 
Valuation and Qualifying Accounts Disclosure [Line Items]
 
 
 
Balance at Beginning of Period
2 
1 
1 
Charged to Costs and Expenses
5 
1 
   
Charged to Other Accounts
   
   
   
Deductions
   
   
   
Balance at End of Period
7 
2 
1 
Union Electric Company |
Allowance For Doubtful Accounts
 
 
 
Valuation and Qualifying Accounts Disclosure [Line Items]
 
 
 
Balance at Beginning of Period
5 
7 
8 
Charged to Costs and Expenses
16 
11 
17 
Charged to Other Accounts
   1
   1
   1
Deductions
16 2
13 2
18 2
Balance at End of Period
5 
5 
7 
Union Electric Company |
Valuation Allowance of Deferred Tax Assets
 
 
 
Valuation and Qualifying Accounts Disclosure [Line Items]
 
 
 
Balance at Beginning of Period
1 
1 
1 
Charged to Costs and Expenses
   
   
   
Charged to Other Accounts
   
   
   
Deductions
   
   
   
Balance at End of Period
1 
1 
1 
Ameren Illinois Company |
Allowance For Doubtful Accounts
 
 
 
Valuation and Qualifying Accounts Disclosure [Line Items]
 
 
 
Balance at Beginning of Period
12 
13 
13 
Charged to Costs and Expenses
19 
19 
24 
Charged to Other Accounts
4 1
2 1
   1
Deductions
22 2
22 2
24 2
Balance at End of Period
13 
12 
13 
Ameren Illinois Company |
Valuation Allowance of Deferred Tax Assets
 
 
 
Valuation and Qualifying Accounts Disclosure [Line Items]
 
 
 
Balance at Beginning of Period
1 
   
   
Charged to Costs and Expenses
   
1 
   
Charged to Other Accounts
   
   
   
Deductions
   
   
   
Balance at End of Period
$ 1 
$ 1