AMEREN ILLINOIS CO, 10-K filed on 3/2/2015
Annual Report
Document And Entity Information (USD $)
12 Months Ended
Dec. 31, 2014
Jan. 30, 2015
Jun. 30, 2014
Document Type
10-K 
 
 
Amendment Flag
false 
 
 
Document Period End Date
Dec. 31, 2014 
 
 
Document Fiscal Year Focus
2014 
 
 
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
 
242,634,798 
 
Entity Voluntary Filers
No 
 
 
Entity Current Reporting Status
Yes 
 
 
Entity Public Float
 
 
$ 9,918,910,542 
Entity Well-known Seasoned Issuer
Yes 
 
 
Union Electric Company
 
 
 
Document Type
10-K 
 
 
Amendment Flag
false 
 
 
Document Period End Date
Dec. 31, 2014 
 
 
Document Fiscal Year Focus
2014 
 
 
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, 2014 
 
 
Document Fiscal Year Focus
2014 
 
 
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 $)
In Millions, except Per Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Operating Revenues:
 
 
 
Electric
$ 4,913 
$ 4,832 
$ 4,857 
Gas
1,140 
1,006 
924 
Total operating revenues
6,053 
5,838 
5,781 
Operating Expenses:
 
 
 
Fuel
826 
845 
714 
Purchased power
454 
502 
780 
Gas purchased for resale
615 
526 
472 
Other operations and maintenance
1,691 
1,617 
1,511 
Depreciation and amortization
745 
706 
673 
Taxes other than income taxes
468 
458 
443 
Total operating expenses
4,799 
4,654 
4,593 
Operating Income
1,254 
1,184 
1,188 
Other Income and Expenses:
 
 
 
Miscellaneous income
79 1
69 1
70 1
Miscellaneous expense
22 1
26 1
37 1
Total other income (expense)
57 
43 
33 
Interest charges
341 
398 
392 
Income Before Income Taxes
970 
829 
829 
Income taxes
377 
311 
307 
Income from Continuing Operations
593 
518 
522 
Income (Loss) from Discontinued Operations, Net of Tax (Note 16)
(1)
(223)
(1,496)
Net Income (Loss)
592 
295 
(974)
Less: Net Income (Loss) Attributable to Noncontrolling Interests:
 
 
 
Continuing Operations
6 
6 
6 
Discontinued Operations
 
 
(6)
Net Income (Loss):
 
 
 
Net income attributable to Ameren Corporation - continuing operations
587 
512 
516 
Discontinued Operations
(1)
(223)
(1,490)
Net income (loss) attributable to Ameren Corporation
586 
289 
(974)
Pension and other postretirement activity, net of income taxes (benefit)
(12)
30 
(8)
Comprehensive Income (Loss)
574 
300 
(932)
Earnings (Loss) per Common Share – Basic:
 
 
 
Continuing Operations - Basic
$ 2.42 
$ 2.11 
$ 2.13 
Discontinued Operations - Basic
$ 0.00 
$ (0.92)
$ (6.14)
Earnings (Loss) per Common Share – Basic
$ 2.42 
$ 1.19 
$ (4.01)
Earnings (Loss) per Common Share – Diluted:
 
 
 
Continuing Operations - Diluted
$ 2.40 
$ 2.10 
$ 2.13 
Discontinued Operations - Diluted
$ 0.00 
$ (0.92)
$ (6.14)
Earnings (Loss) per Common Share – Diluted
$ 2.40 
$ 1.18 
$ (4.01)
Dividends per Common Share
$ 1.61 
$ 1.60 
$ 1.600 
Average Common Shares Outstanding - Basic
242.6 
242.6 
242.6 
Average Common Shares Outstanding - Diluted
244.4 
244.5 
243.0 
Union Electric Company
 
 
 
Operating Revenues:
 
 
 
Electric
3,388 
3,379 
3,132 
Gas
164 
161 
139 
Other
1 
1 
1 
Total operating revenues
3,553 
3,541 
3,272 
Operating Expenses:
 
 
 
Fuel
826 
845 
714 
Purchased power
119 
127 
78 
Gas purchased for resale
82 
78 
64 
Other operations and maintenance
946 
915 
827 
Depreciation and amortization
473 
454 
440 
Taxes other than income taxes
322 
319 
304 
Total operating expenses
2,768 
2,738 
2,427 
Operating Income
785 
803 
845 
Other Income and Expenses:
 
 
 
Miscellaneous income
60 
58 
63 
Miscellaneous expense
12 
11 
14 
Total other income (expense)
48 
47 
49 
Interest charges
211 
210 
223 
Income Before Income Taxes
622 
640 
671 
Income taxes
229 
242 
252 
Net Income (Loss)
393 
398 
419 
Net Income (Loss):
 
 
 
Net income (loss) attributable to Ameren Corporation
393 
398 
419 
Other Comprehensive Income
0 
0 
0 
Comprehensive Income (Loss)
393 
398 
419 
Preferred Stock Dividends
3 
3 
3 
Net Income Available to Common Stockholder
390 
395 
416 
Ameren Illinois Company
 
 
 
Operating Revenues:
 
 
 
Electric
1,522 
1,461 
1,739 
Gas
976 
847 
786 
Other
 
3 
 
Total operating revenues
2,498 
2,311 
2,525 
Operating Expenses:
 
 
 
Purchased power
343 
380 
705 
Gas purchased for resale
533 
448 
408 
Other operations and maintenance
771 
693 
684 
Depreciation and amortization
263 
243 
221 
Taxes other than income taxes
138 
132 
130 
Total operating expenses
2,048 
1,896 
2,148 
Operating Income
450 
415 
377 
Other Income and Expenses:
 
 
 
Miscellaneous income
17 
10 
7 
Miscellaneous expense
8 
9 
17 
Total other income (expense)
9 
1 
(10)
Interest charges
112 
143 
129 
Income Before Income Taxes
347 
273 
238 
Income taxes
143 
110 
94 
Net Income (Loss)
204 
163 
144 
Net Income (Loss):
 
 
 
Net income (loss) attributable to Ameren Corporation
204 
163 
144 
Pension and other postretirement activity, net of income taxes (benefit)
(3)
(3)
(3)
Comprehensive Income (Loss)
201 
160 
141 
Preferred Stock Dividends
3 
3 
3 
Net Income Available to Common Stockholder
$ 201 
$ 160 
$ 141 
Consolidated Statement Of Income (Loss) (Parenthetical) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Pension and other postretirement activity, tax (benefit)
$ (7)
$ 16 
$ (6)
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Income from Continuing Operations
$ 593 
$ 518 
$ 522 
Pension and other postretirement activity, net of income taxes (benefit)
(12)
30 
(8)
Comprehensive Income (Loss) from Continuing Operations
581 
548 
514 
Less: Comprehensive Income from Continuing Operations Attributable to Noncontrolling Interests
6 
6 
6 
Comprehensive Income from Continuing Operations Attributable to Ameren Corporation
575 
542 
508 
Income (Loss) from Discontinued Operations, Net of Tax (Note 16)
(1)
(223)
(1,496)
Comprehensive Income from Continuing Operations Attributable to Ameren Corporation
 
(18)
58 
Comprehensive Income (Loss) from Discontinued Operations
(1)
(241)
(1,438)
Less: Comprehensive Income from Discontinuing Operations Attributable to Noncontrolling Interest
 
1 
2 
Comprehensive Income (Loss) from Discontinued Operations Attributable to Ameren Corporation
(1)
(242)
(1,440)
Comprehensive Income (Loss)
574 
300 
(932)
Ameren Illinois Company
 
 
 
Pension and other postretirement activity, net of income taxes (benefit)
(3)
(3)
(3)
Comprehensive Income (Loss)
$ 201 
$ 160 
$ 141 
Consolidated Statement Of Comprehensive Income (Parenthetical) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Pension and other postretirement activity, tax (benefit)
$ (7)
$ 16 
$ (6)
Other Comprehensive Income (Loss) from Discontinued Operations Tax (Benefit)
$ 0 
$ (10)
$ 40 
Consolidated Balance Sheet (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Current Assets:
 
 
Cash and cash equivalents
$ 5 
$ 30 
Accounts receivable - trade (less allowance for doubtful accounts)
423 
404 
Unbilled revenue
265 
304 
Miscellaneous accounts and notes receivable
81 
196 
Materials and supplies
524 
526 
Current regulatory assets
295 
156 
Current accumulated deferred income taxes, net
352 
106 
Other current assets
86 
85 
Assets of discontinued operations (Note 16)
15 
165 
Total current assets
2,046 
1,972 
Property, Plant and Equipment, Net
17,424 1
16,205 1
Investments and Other Assets:
 
 
Nuclear decommissioning trust fund
549 
494 
Goodwill
411 
411 
Regulatory assets
1,582 
1,240 
Other assets
664 
720 
Total investments and other assets
3,206 
2,865 
TOTAL ASSETS
22,676 
21,042 
Current Liabilities:
 
 
Current maturities of long-term debt
120 
534 
Short-term debt
714 
368 
Accounts and wages payable
711 
806 
Taxes accrued
46 
55 
Interest accrued
85 
86 
Current regulatory liabilities
106 
216 
Other current liabilities
434 
351 
Liabilities of discontinued operations (Note 16)
33 
45 
Total current liabilities
2,249 
2,461 
Long-term Debt, Net
6,120 
5,504 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
3,923 
3,250 
Accumulated deferred investment tax credits
64 
63 
Regulatory liabilities
1,850 
1,705 
Asset retirement obligations
396 
369 
Pension and other postretirement benefits
705 
466 
Other deferred credits and liabilities
514 
538 
Total deferred credits and other liabilities
7,452 
6,391 
Commitments and Contingencies (Notes 2, 10, 14 and 15)
   
   
Stockholders' Equity:
 
 
Common stock
2 
2 
Other paid-in capital, principally premium on common stock
5,617 
5,632 
Preferred stock not subject to mandatory redemption
142 
142 
Retained earnings
1,103 
907 
Accumulated other comprehensive income (loss)
(9)
3 
Total stockholders' equity
6,713 
6,544 
Noncontrolling Interests
142 
142 
Total equity
6,855 
6,686 
TOTAL LIABILITIES AND EQUITY
22,676 
21,042 
Union Electric Company
 
 
Current Assets:
 
 
Cash and cash equivalents
1 
1 
Accounts receivable - trade (less allowance for doubtful accounts)
190 
191 
Accounts receivable - affiliates
65 
1 
Unbilled revenue
146 
168 
Miscellaneous accounts and notes receivable
35 
57 
Materials and supplies
347 
352 
Current regulatory assets
163 
118 
Current accumulated deferred income taxes, net
49 
20 
Other current assets
92 
71 
Total current assets
1,039 
959 
Property, Plant and Equipment, Net
10,867 1
10,452 1
Investments and Other Assets:
 
 
Nuclear decommissioning trust fund
549 
494 
Regulatory assets
695 
534 
Other assets
391 
465 
Total investments and other assets
1,635 
1,493 
TOTAL ASSETS
13,541 
12,904 
Current Liabilities:
 
 
Current maturities of long-term debt
120 
109 
Due to Related Parties, Current
0 
105 
Short-term debt
97 
0 
Accounts and wages payable
405 
387 
Accounts payable - affiliates
56 
30 
Taxes accrued
32 
220 
Interest accrued
58 
57 
Current regulatory liabilities
18 
57 
Other current liabilities
117 
82 
Total current liabilities
903 
1,047 
Long-term Debt, Net
3,879 
3,648 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
2,806 
2,524 
Accumulated deferred investment tax credits
61 
59 
Regulatory liabilities
1,147 
1,041 
Asset retirement obligations
389 
366 
Pension and other postretirement benefits
274 
189 
Other deferred credits and liabilities
30 
37 
Total deferred credits and other liabilities
4,707 
4,216 
Commitments and Contingencies (Notes 2, 10, 14 and 15)
   
   
Stockholders' Equity:
 
 
Common stock
511 
511 
Other paid-in capital, principally premium on common stock
1,569 
1,560 
Preferred stock not subject to mandatory redemption
80 
80 
Retained earnings
1,892 
1,842 
Total stockholders' equity
4,052 
3,993 
TOTAL LIABILITIES AND EQUITY
13,541 
12,904 
Ameren Illinois Company
 
 
Current Assets:
 
 
Cash and cash equivalents
1 
1 
Accounts receivable - trade (less allowance for doubtful accounts)
212 
201 
Accounts receivable - affiliates
22 
0 
Unbilled revenue
119 
135 
Miscellaneous accounts and notes receivable
9 
13 
Materials and supplies
177 
174 
Current regulatory assets
129 
38 
Current accumulated deferred income taxes, net
160 
45 
Other current assets
15 
26 
Total current assets
844 
633 
Property, Plant and Equipment, Net
6,165 
5,589 
Investments and Other Assets:
 
 
Goodwill
411 
411 
Regulatory assets
883 
701 
Other assets
78 
120 
Total investments and other assets
1,372 
1,232 
TOTAL ASSETS
8,381 
7,454 
Current Liabilities:
 
 
Current maturities of long-term debt
 
0 
Borrowings from money pool
15 
56 
Short-term debt
32 
 
Accounts and wages payable
207 
243 
Accounts payable - affiliates
50 
18 
Taxes accrued
17 
23 
Customer deposits
77 
79 
Mark-to-market derivative liabilities
42 
36 
Environmental remediation
52 
43 
Current regulatory liabilities
84 
159 
Other current liabilities
124 
114 
Total current liabilities
700 
771 
Long-term Debt, Net
2,241 
1,856 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
1,408 
1,116 
Accumulated deferred investment tax credits
3 
4 
Regulatory liabilities
703 
664 
Pension and other postretirement benefits
277 
197 
Accrued Environmental Loss Contingencies, Noncurrent
199 
232 
Other deferred credits and liabilities
189 
166 
Total deferred credits and other liabilities
2,779 
2,379 
Commitments and Contingencies (Notes 2, 10, 14 and 15)
   
   
Stockholders' Equity:
 
 
Common stock
0 
0 
Other paid-in capital, principally premium on common stock
1,980 
1,965 
Preferred stock not subject to mandatory redemption
62 
62 
Retained earnings
611 
410 
Accumulated other comprehensive income (loss)
8 
11 
Total stockholders' equity
2,661 
2,448 
TOTAL LIABILITIES AND EQUITY
$ 8,381 
$ 7,454 
Consolidated Balance Sheet (Parenthetical) (USD $)
In Millions, except Share data, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Accounts receivable - trade, allowance for doubtful accounts
$ 21 
$ 18 
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
8 
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 
$ 13 
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Cash Flows From Operating Activities:
 
 
 
Net income (loss)
$ 592 
$ 295 
$ (974)
(Income) Loss from discontinued operations, net of tax
1 
223 
1,496 
Adjustments to reconcile net income to net cash provided by operating activities:
 
 
 
Depreciation and amortization
710 
666 
633 
Amortization of nuclear fuel
81 
71 
83 
Amortization of debt issuance costs and premium/discounts
22 
24 
20 
Deferred income taxes and investment tax credits, net
451 
410 
257 
Allowance for equity funds used during construction
(34)1
(37)1
(36)1
Share-based Compensation
25 
27 
29 
Other
(24)
23 
(7)
Changes in assets and liabilities:
 
 
 
Receivables
31 
(60)
30 
Materials and supplies
3 
60 
(28)
Accounts and wages payable
10 
81 
(34)
Taxes accrued
(44)
(195)
(4)
Regulatory assets and liabilities
(281)
29 
14 
Assets, other
30 
20 
40 
Liabilities, other
(28)
(14)
5 
Pension and other postretirement benefits
(10)
(28)
(23)
Counterparty collateral, net
22 
41 
41 
Premiums paid on long-term debt repurchases
 
 
(138)
Net cash provided by operating activities - continuing operations
1,557 
1,636 
1,404 
Net cash provided by operating activities - discontinued operations
(6)
57 
286 
Net cash provided by operating activities
1,551 
1,693 
1,690 
Cash Flows From Investing Activities:
 
 
 
Capital expenditures
(1,785)
(1,379)
(1,063)
Nuclear fuel expenditures
(74)
(45)
(91)
Purchases of securities - nuclear decommissioning trust fund
(405)
(214)
(403)
Sales and maturities of securities - nuclear decommissioning trust fund
391 
196 
384 
Proceeds from Collection of Notes Receivable
95 
6 
 
Contributions to Note Receivable
(89)
(5)
 
Other
11 
1 
20 
Net cash used in investing activities - continuing operations
(1,856)
(1,440)
(1,153)
Net cash used in investing activities - discontinued operations
139 
(283)
(157)
Net cash used in investing activities
(1,717)
(1,723)
(1,310)
Cash Flows From Financing Activities:
 
 
 
Dividends on common stock
(390)
(388)
(382)
Dividends paid to noncontrolling interest holders
(6)
(6)
(6)
Short-term debt and credit facility repayments, net
346 
368 
(148)
Redemptions, repurchases, and maturities:
 
 
 
Long-term debt
(697)
(399)
(760)
Issuances:
 
 
 
Long-term debt
898 
278 
882 
Capital issuance costs
(11)
(2)
(16)
Other
1 
 
4 
Net cash provided by (used in) financing activities
141 
(149)
(426)
Net change in cash and cash equivalents
(25)
(179)
(46)
Cash and cash equivalents at beginning of year
30 
209 
255 
Cash and cash equivalents at end of year
5 
30 
209 
Less: Cash and cash equivalents of discontinued operations at end of year
 
 
25 
Cash and cash equivalents at beginning of year
30 
184 
 
Cash and cash equivalents at end of year
5 
30 
184 
Noncash financing activity – dividends on common stock
 
 
7 
Cash Paid (Refunded) During the Year:
 
 
 
Interest net of capitalized
333 
393 
433 
Income taxes, net
(27)
8 
1 
Union Electric Company
 
 
 
Cash Flows From Operating Activities:
 
 
 
Net income (loss)
393 
398 
419 
Adjustments to reconcile net income to net cash provided by operating activities:
 
 
 
Depreciation and amortization
442 
419 
407 
Amortization of nuclear fuel
81 
71 
83 
FAC prudence review charge
 
26 
 
Amortization of debt issuance costs and premium/discounts
7 
7 
6 
Deferred income taxes and investment tax credits, net
245 
65 
287 
Allowance for equity funds used during construction
(32)
(31)
(31)
Other
3 
1 
8 
Changes in assets and liabilities:
 
 
 
Receivables
(10)
(59)
27 
Materials and supplies
8 
45 
(48)
Accounts and wages payable
25 
42 
(27)
Taxes accrued
(197)
100 
(46)
Regulatory assets and liabilities
(68)
68 
(50)
Assets, other
52 
18 
15 
Liabilities, other
 
(29)
14 
Pension and other postretirement benefits
1 
2 
2 
Premiums paid on long-term debt repurchases
 
 
(62)
Net cash provided by operating activities
950 
1,143 
1,004 
Cash Flows From Investing Activities:
 
 
 
Capital expenditures
(747)
(648)
(595)
Nuclear fuel expenditures
(74)
(45)
(91)
Purchases of securities - nuclear decommissioning trust fund
(405)
(214)
(403)
Sales and maturities of securities - nuclear decommissioning trust fund
391 
196 
384 
Money pool advances, net
 
(24)
24 
Tax grants received related to renewable energy properties
 
 
18 
Other
(2)
 
8 
Net cash used in investing activities
(837)
(687)
(703)
Cash Flows From Financing Activities:
 
 
 
Dividends on common stock
(340)
(460)
(400)
Return of capital to parent
(215)
 
 
Dividends on preferred stock
(3)
(3)
(3)
Money pool borrowings, net
(105)
105 
 
Short-term debt and credit facility repayments, net
97 
 
 
Redemptions, repurchases, and maturities:
 
 
 
Long-term debt
(109)
(249)
(427)
Issuances:
 
 
 
Long-term debt
350 
 
482 
Capital issuance costs
(3)
 
(7)
Capital contribution from parent
215 
4 
1 
Net cash provided by (used in) financing activities
(113)
(603)
(354)
Net change in cash and cash equivalents
 
(147)
(53)
Cash and cash equivalents at beginning of year
1 
148 
201 
Cash and cash equivalents at end of year
1 
1 
148 
Noncash Or Part Noncash Capital Contribution From Parent
9 
 
 
Cash Paid (Refunded) During the Year:
 
 
 
Interest net of capitalized
203 
212 
220 
Income taxes, net
215 
86 
(3)
Ameren Illinois Company
 
 
 
Cash Flows From Operating Activities:
 
 
 
Net income (loss)
204 
163 
144 
Adjustments to reconcile net income to net cash provided by operating activities:
 
 
 
Depreciation and amortization
259 
238 
214 
Amortization of debt issuance costs and premium/discounts
13 
15 
11 
Deferred income taxes and investment tax credits, net
196 
104 
104 
Allowance for equity funds used during construction
(2)
(6)
(5)
Other
(19)
4 
(11)
Changes in assets and liabilities:
 
 
 
Receivables
(13)
50 
23 
Materials and supplies
(4)
15 
20 
Accounts and wages payable
7 
19 
(21)
Taxes accrued
(7)
28 
3 
Regulatory assets and liabilities
(215)
(35)
64 
Assets, other
15 
5 
19 
Liabilities, other
1 
10 
11 
Pension and other postretirement benefits
(6)
(8)
(26)
Counterparty collateral, net
14 
43 
40 
Premiums paid on long-term debt repurchases
 
 
(76)
Net cash provided by operating activities
445 
651 
519 
Cash Flows From Investing Activities:
 
 
 
Capital expenditures
(835)
(701)
(442)
Other
7 
6 
5 
Net cash used in investing activities
(828)
(695)
(437)
Cash Flows From Financing Activities:
 
 
 
Dividends on common stock
 
(110)
(189)
Dividends on preferred stock
(3)
(3)
(3)
Money pool borrowings, net
(41)
32 
24 
Short-term debt and credit facility repayments, net
32 
 
 
Redemptions, repurchases, and maturities:
 
 
 
Long-term debt
(163)
(150)
(333)
Issuances:
 
 
 
Long-term debt
548 
278 
400 
Capital issuance costs
(6)
(2)
(6)
Capital contribution from parent
15 
 
 
Other
1 
 
4 
Net cash provided by (used in) financing activities
383 
45 
(103)
Net change in cash and cash equivalents
 
1 
(21)
Cash and cash equivalents at beginning of year
1 
 
21 
Cash and cash equivalents at end of year
1 
1 
 
Cash Paid (Refunded) During the Year:
 
 
 
Interest net of capitalized
110 
112 
125 
Income taxes, net
$ (44)
$ (23)
$ (22)
Consolidated Statement Of Cash Flows (Parenthetical) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Capitalized interest
$ 18 
$ 37 
$ 30 
Union Electric Company
 
 
 
Capitalized interest
16 
16 
15 
Ameren Illinois Company
 
 
 
Capitalized interest
$ 2 
$ 4 
$ 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
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, 2011
 
$ 2 
$ 5,598 
$ 2,369 
$ 7 
$ (57)
 
$ 149 
 
 
 
$ 1,555 
 
$ 1,891 
 
$ 1,965 
$ 62 
$ 408 
$ 17 
 
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 
 
 
 
 
 
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 
 
 
 
 
 
 
 
 
 
 
 
 
Dividends
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Stockholders' equity, end of year at Dec. 31, 2012
 
 
 
 
 
 
 
 
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 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 
 
 
 
 
 
Stock-based compensation activity
 
 
16 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Capital contribution from parent
 
 
 
 
 
 
 
 
 
4 
 
4 
 
 
 
0 
 
 
 
 
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 
 
 
 
 
 
 
 
 
 
 
 
 
Dividends
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 
62 
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 
 
 
 
 
 
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 
 
 
 
62 
 
11 
 
End of year (shares) at Dec. 31, 2013
242.6 
 
 
 
 
 
 
 
 
102.1 
 
 
 
 
25.5 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
98 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss) attributable to Ameren Corporation
96 
 
 
 
 
 
 
 
 
48 
 
 
 
 
54 
 
 
 
 
 
Stockholders' equity, end of year at Mar. 31, 2014
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Beginning of year at Dec. 31, 2013
6,686 
2 
5,632 
907 
0 
3 
3 
142 
 
 
511 
1,560 
80 
1,842 
 
1,965 
62 
410 
11 
11 
Beginning of year (shares) at Dec. 31, 2013
242.6 
 
 
 
 
 
 
 
 
102.1 
 
 
 
 
25.5 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
592 
 
 
 
 
 
 
 
 
393 
 
 
 
393 
204 
 
 
204 
 
 
Net income (loss) attributable to Ameren Corporation
586 
 
 
586 
 
 
 
 
 
393 
 
 
 
 
204 
 
 
 
 
 
Stock-based compensation activity
 
 
(15)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Capital contribution from parent
 
 
 
 
 
 
 
 
 
215 
 
224 
 
 
15 
15 
 
 
 
 
Common stock dividends
 
 
 
(390)
 
 
 
 
 
 
 
 
 
(340)
 
 
 
0 
 
 
Preferred stock dividends
 
 
 
 
 
 
 
 
 
 
 
 
 
(3)
 
 
 
(3)
 
 
Change in derivative financial instruments
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Divestiture of derivative financial instruments
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Change in deferred retirement benefit costs
12 
 
 
 
 
(12)
 
 
 
 
 
 
 
 
3 
 
 
 
 
(3)
Divestiture of deferred retirement benefit costs
 
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income attributable to noncontrolling interest holder
 
 
 
 
 
 
 
6 
 
 
 
 
 
 
 
 
 
 
 
 
Dividends paid to noncontrolling interest holders
 
 
 
 
 
 
 
(6)
 
 
 
 
 
 
 
 
 
 
 
 
Divestiture of noncontrolling interest
 
 
 
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
Other
 
 
 
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
Return of capital to parent
 
 
 
 
 
 
 
 
 
215 
 
(215)
 
 
 
 
 
 
 
 
Stockholders' equity, end of year at Dec. 31, 2014
6,713 
 
 
 
 
 
 
 
6,713 
4,052 
 
 
 
 
2,661 
 
 
 
 
 
End of year at Dec. 31, 2014
6,855 
2 
5,617 
1,103 
0 
(9)
(9)
142 
 
 
511 
1,569 
80 
1,892 
 
1,980 
 
611 
8 
8 
End of year (shares) at Dec. 31, 2014
242.6 
 
 
 
 
 
 
 
 
102.1 
 
 
 
 
25.5 
 
 
 
 
 
Beginning of year at Sep. 30, 2014
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Increase (Decrease) in Stockholders' Equity [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss)
49 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Net income (loss) attributable to Ameren Corporation
48 
 
 
 
 
 
 
 
 
(5)
 
 
 
 
46 
 
 
 
 
 
Stockholders' equity, end of year at Dec. 31, 2014
6,713 
 
 
 
 
 
 
 
6,713 
4,052 
 
 
 
 
2,661 
 
 
 
 
 
End of year at Dec. 31, 2014
$ 6,855 
$ 2 
 
 
 
 
$ (9)
 
 
 
$ 511 
 
$ 80 
 
 
 
 
 
$ 8 
 
End of year (shares) at Dec. 31, 2014
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 the FERC. Ameren’s primary assets are its equity interests in its subsidiaries, including Ameren Missouri and Ameren Illinois. 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 rate-regulated electric and natural gas transmission and distribution businesses 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 was 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 813,000 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. ATXI is developing MISO-approved electric transmission projects, including the Illinois Rivers, Spoon River, and Mark Twain projects. Ameren is also pursuing reliability projects within Ameren Missouri's and Ameren Illinois' service territories as well as competitive electric transmission investment opportunities outside of these territories, including investments outside of MISO.
In December 2013, Ameren completed the divestiture of New AER to IPH. In January 2014, Medina Valley completed its sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital. In addition, in 2013, Ameren abandoned the Meredosia and Hutsonville energy centers upon the completion of the divestiture of New AER to IPH. Ameren has begun to demolish the Hutsonville energy center and expects to demolish the Meredosia energy center thereafter. As a result of these events, Ameren 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 these transactions.
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 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
We are regulated by the MoPSC, the ICC, and the FERC. We defer certain costs as assets pursuant to actions of rate regulators or because of expectations that we will be able to recover such costs in rates charged to customers. We 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 solar rebate program tracker, a storm restoration cost tracker, and the MEEIA energy efficiency rider. Ameren Illinois' and ATXI's electric transmission rates are subject to formula ratemaking. Additionally, Ameren Illinois' electric distribution business participates in the performance-based formula ratemaking process established pursuant to the IEIMA. Ameren Illinois also 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.
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 by 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, 2014 and 2013:
 
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2014
 
 
 
 
 
 
Fuel(a)
 
$
134

 
$
—

 
$
134

Gas stored underground
 
16

 
111

 
127

Other materials and supplies
 
197

 
66

 
263

 
 
$
347

 
$
177

 
$
524

2013
 
 
 
 
 
 
Fuel(a)
 
$
144

 
$
—

 
$
144

Gas stored underground
 
17

 
110

 
127

Other materials and supplies
 
191

 
64

 
255

 
 
$
352

 
$
174

 
$
526

(a)
Consists of coal, oil, and propane.
Property and Plant, Net
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. If environmental expenditures are related to assets currently in use, as in the case of the installation of pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset. 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 2014, 2013, and 2012 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 used during 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Ameren Missouri
7
%
 
8
%
 
8
%
Ameren Illinois
2
%
 
8
%
 
9
%

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 goodwill of $411 million at December 31, 2014, and 2013.
All of Ameren's and Ameren Illinois' goodwill at December 31, 2014 and 2013, was assigned to the Ameren Illinois reporting unit, which is also the Ameren Illinois reportable segment.
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, 2014. 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, 2014, 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, 2014, 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 30-year United States Treasury bonds;
•
a potential reduction in the FERC-allowed return on equity related to transmission services; and
•
actual and forecasted financial performance.
The goodwill assigned to the Ameren Illinois reporting unit on the December 31, 2014 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.
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 an impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets to the carrying value of the assets. If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount by which the carrying value 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 estimated fair value less cost to sell.
Investments
Ameren and Ameren Missouri record investments held in Ameren Missouri's nuclear decommissioning trust fund at fair value. 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. In addition, Ameren and Ameren Missouri recognize a regulatory liability on their balance sheets for gains on investments held in the nuclear decommissioning trust fund. As of December 31, 2014, the nuclear decommissioning trust fund had cumulative gains. 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.
Asset Retirement Obligations
We are required 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 expenditures 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 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. Ameren and Ameren Missouri are evaluating the potential effect of the EPA's new rule regarding the management and disposal of CCR on their AROs associated with ash ponds. See Note 15 – Commitments and Contingencies.
Asset removal costs accrued by our rate-regulated operations that do not constitute legal obligations are classified as regulatory liabilities. 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, 2014 and 2013:
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
 
Balance at December 31, 2012
$
346

 
$
3

 
$
349

 
Liabilities settled
(1
)
 
(a)

 
(1
)
 
Accretion in 2013(b)
19

 
(a)

 
19

 
Change in estimates(c)
2

 
(a)

 
2

 
Balance at December 31, 2013
$
366

 
$
3

(d) 
$
369

 
Liabilities incurred
2

 
—

 
2

 
Liabilities settled
(2
)
 
(a)

 
(2
)
 
Accretion in 2014(b)
21

 
(a)

 
21

 
Change in estimates(c)(e)
2

 
4

 
6

 
Balance at December 31, 2014
$
389

 
$
7

(d) 
$
396

 

(a)
Less than $1 million.
(b)
Accretion expense was recorded as an increase to regulatory assets at Ameren Missouri and Ameren Illinois.
(c)
Ameren Missouri changed its fair value estimates for asbestos removal in 2013 and 2014 and for certain CCR facilities in 2013.
(d)
Included in “Other deferred credits and liabilities” on the balance sheet.
(e)
Ameren Illinois changed its fair value estimate for asbestos removal in 2014.
Ameren and Ameren Missouri have nuclear decommissioning trust fund assets of $549 million and $494 million as of December 31, 2014 and 2013, respectively, which are for decommissioning of the Callaway energy center.
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.
Noncontrolling Interests
As of December 31, 2014 and 2013, Ameren’s noncontrolling interests included the preferred stock of Ameren Missouri and Ameren Illinois.
Operating Revenue
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.
Ameren Illinois participates in the performance-based formula ratemaking framework pursuant to the IEIMA. The IEIMA provides for an annual reconciliation of Ameren Illinois' electric delivery service revenue requirement. As of each balance sheet date, Ameren Illinois records its estimate of the electric delivery service revenue effect resulting from the reconciliation of the revenue requirement necessary to reflect the actual recoverable costs incurred for that year with the revenue requirement that was reflected in customer rates for that year. If the current year's revenue requirement is greater than the revenue requirement reflected in that year's customer rates, 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 reflected in that year's customer rates, 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.
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's 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 recognize revenues once the resettlement amount is received.
Nuclear Fuel
Ameren Missouri’s cost of nuclear fuel is capitalized and then amortized to fuel expense on a unit-of-production basis. The 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 without a traditional rate case proceeding. See Note 2 – Rate and Regulatory Matters for the regulatory assets and liabilities recorded at December 31, 2014 and 2013, related to the rate-adjustment mechanisms discussed below.
In Ameren Missouri’s and Ameren Illinois’ natural gas utility jurisdictions, changes in natural gas costs are reflected in billings to their natural gas utility customers through PGA clauses. The difference between actual natural gas costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either billed or refunded to natural gas utility customers in a subsequent period.
In Ameren Illinois’ retail electric utility jurisdiction, changes in purchased power and transmission service costs are reflected in billings to its electric utility customers through pass-through rate-adjustment clauses. The difference between actual purchased power and transmission service costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is 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 and purchased power costs, including transportation charges and revenues, net of off-system sales, greater or less than the amount set in base rates, subject to MoPSC prudence review. The difference between the actual amounts incurred for these items and the amounts recovered from Ameren Missouri customers' base rates is deferred as a regulatory asset or liability. The deferred amounts are either billed or refunded to electric utility customers in a subsequent period.
Stock-based Compensation
Stock-based compensation cost is measured at the grant date based on the fair value of the award, net of an assumed forfeiture rate. 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
Ameren Missouri and Ameren Illinois collect certain excise taxes from customers that are levied on the sale or distribution of natural gas and electricity. Excise taxes are levied on Ameren Missouri's electric and natural gas businesses and on Ameren Illinois' natural gas business and are recorded gross in “Operating Revenues – Electric,” “Operating Revenues – Gas,” and “Operating Expenses – Taxes other than income taxes” on the statement of income or the statement of income and comprehensive income. Excise taxes for electric service in Illinois are levied on the customer and are therefore not included in Ameren Illinois' revenues and expenses. They are instead 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 December 31, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Ameren Missouri
$
151

 
$
152

 
$
139

Ameren Illinois
64

 
61

 
54

Ameren
$
215

 
$
213

 
$
193


Unamortized Debt Discounts, Premiums, and Issuance Costs
Long-term debt discounts, premiums, and issuance costs are amortized over the lives of the related issuances. Credit facility fees are amortized over the credit facility term.
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 deferred tax liabilities that 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 through future customer rates of tax benefits related to the equity component of allowance for funds used during construction, as well as the effects of tax rate changes.
Investment tax credits used on tax returns for prior years have been deferred as a non-current liability. 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 rates for future lower income taxes associated with the amortization of the investment tax credits. See Note 13 – Income Taxes.
Ameren Missouri, Ameren Illinois, and all the other Ameren subsidiary companies are parties to a tax allocation agreement with Ameren (parent) 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 or refunded had the party been separately subject to tax. Any net benefit attributable to the parent is reallocated to the other parties. This reallocation is treated as a capital contribution to the party receiving the benefit.
Earnings per Share
Basic earnings per share is computed by dividing net income attributable to Ameren Corporation common stockholders by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed by dividing net income attributable to common stockholders 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, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Net income (loss) attributable to Ameren Corporation:
 
 
 
 
 
Continuing operations
$
587

 
$
512

 
$
516

Discontinued operations
(1
)
 
(223
)
 
(1,490
)
Net income (loss) attributable to Ameren Corporation
$
586

 
$
289

 
$
(974
)
 
 
 
 
 
 
Average common shares outstanding – basic
242.6

 
242.6

 
242.6

Assumed settlement of performance share units
1.8

 
1.9

 
0.4

Average common shares outstanding – diluted
244.4

 
244.5

 
243.0

 
 
 
 
 
 
Earnings (loss) per common share – basic:
 
 
 
 
 
Continuing operations
$
2.42

 
$
2.11

 
$
2.13

Discontinued operations
—

 
(0.92
)
 
(6.14
)
Earnings (loss) per common share – basic
$
2.42

 
$
1.19

 
$
(4.01
)
 
 
 
 
 
 
Earnings (loss) per common share – diluted:
 
 
 
 
 
Continuing operations
$
2.40

 
$
2.10

 
$
2.13

Discontinued operations
—

 
(0.92
)
 
(6.14
)
Earnings (loss) per common share – diluted
$
2.40

 
$
1.18

 
$
(4.01
)

There were no potentially dilutive securities excluded from the diluted earnings per share calculations for the years ended December 31, 2014, 2013, and 2012.
Capital Contributions and Return of Capital
In 2014, Ameren Missouri and Ameren Illinois received cash capital contributions of $215 million and $15 million, respectively, from Ameren (parent) as a result of the tax allocation agreement. Additionally, as of December 31, 2014, Ameren Missouri accrued a $9 million capital contribution related to the same agreement. In 2014, Ameren Missouri returned capital of $215 million to Ameren (parent).
Supplemental Cash Flow Information
The following table presents additional information regarding Ameren's consolidated statement of cash flows for the years ended December 31, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Cash paid (refunded) during the year:
Interest
 
 
 
 
 
Continuing operations(a)
$
333

 
$
362

 
$
384

Discontinued operations(b)
—

 
31

 
49

 
$
333

 
$
393

 
$
433

 
 
 
 
 
 
Income taxes, net
 
 
 
 
 
Continuing Operations
$
(41
)
 
$
116

 
$
10

Discontinued Operations
14

 
(108
)
 
(9
)
 
$
(27
)
 
$
8

 
$
1

(a)
Net of $18 million, $20 million, and $17 million capitalized, respectively.
(b)
Net of $- million, $17 million, and $13 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 an Unrecognized Tax Benefit
In 2013, FASB issued additional authoritative accounting guidance, which became effective in 2014, 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. The objective of this guidance is to eliminate diversity in practice related to the presentation of certain unrecognized tax benefits. 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. Previously, unrecognized tax benefits were recorded in “Other deferred credits and liabilities” on Ameren's, Ameren Missouri's, and Ameren Illinois' respective balance sheets. Beginning in 2014, unrecognized tax benefits are recorded as a reduction to the deferred tax assets for net operating losses and tax credit carryforwards within "Accumulated deferred income taxes, net" on our balance sheets. Unrecognized tax benefits that exceed these carryforwards are recorded in “Other deferred credits and liabilities” on the respective balance sheets. At December 31, 2014, unrecognized tax benefits of $52 million, $- million, and $- million were recorded in "Accumulated deferred income taxes, net" on Ameren's, Ameren Missouri's, and Ameren Illinois' balance sheets, respectively. At December 31, 2013, unrecognized tax benefits of $84 million, $15 million, and $- million previously recorded in "Other deferred credits and liabilities" on Ameren's, Ameren Missouri's, and Ameren Illinois' respective balance sheets were reclassified to "Accumulated deferred income taxes, net" for comparative purposes. The implementation of the additional authoritative accounting guidance did not affect the Ameren Companies' results of operations or liquidity, as this guidance is presentation-related only.
Reporting Discontinued Operations and Disclosures of Components of an Entity
In 2014, FASB issued authoritative accounting guidance that changes the criteria for reporting and qualifying for discontinued operations. Under the new guidance, a component of an entity, or a group of components of an entity, that either meets the criteria to be classified as held for sale or is disposed of by sale or otherwise is required to be reported in discontinued operations if the disposal represents a strategic shift that had, or will have, a major effect on an entity's operations and financial results. The guidance includes expanded disclosure requirements for discontinued operations and additional disclosures about a disposal of an individually significant component of an entity that does not qualify for discontinued operations presentation. The guidance is effective for the Ameren Companies in the first quarter of 2015 for components that are classified as held for sale or disposed of on or after January 1, 2015. Early adoption is permitted, but only for disposals or classifications as held for sale that have not been reported in financial statements previously issued. Therefore, Ameren's existing discontinued operations are not subject to the new disclosure requirements. The guidance will not affect the Ameren Companies' results of operations, financial position, or liquidity, as this guidance is presentation-related only.
Revenue from Contracts with Customers
In 2014, FASB issued authoritative accounting guidance to clarify the principles for recognizing revenue and to develop a common revenue standard for GAAP. The guidance requires an entity to recognize an amount of revenue for the transfer of promised goods or services to customers that reflects the consideration which the entity expects to be entitled to in exchange for those goods or services. The guidance also requires additional disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The guidance will be effective for the Ameren Companies in the first quarter of 2017. The guidance allows entities to choose one of two transition methods, either by applying the guidance retrospectively to each reporting period presented or by recording a cumulative effect adjustment to retained earnings in the period of initial adoption. The Ameren Companies are currently assessing the impacts of this guidance on their results of operations, financial position, and liquidity, as well as the transition method that they will use to adopt the guidance.
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 effect on our results of operations, financial position, or liquidity.
Missouri
2014 Electric Rate Case
In July 2014, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for electric service. The request, as amended in February 2015, seeks an annual revenue increase of approximately $190 million. The amended rate request seeks recovery of increased net energy costs and rebates provided for customer-installed solar generation, as well as recovery of, and a return on, electric infrastructure investments. Approximately $100 million of the amended request relates to an increase in net energy costs above the levels included in base rates authorized by the MoPSC in its December 2012 electric rate order. Absent initiation of this general rate proceeding, 95% of those costs would have been reflected in rate adjustments implemented under Ameren Missouri’s existing FAC. The amended electric rate increase request is based on a 10.4% return on common equity, a capital structure composed of 51.8% common equity, an electric rate base of $7 billion, and a test year ended March 31, 2014, with certain pro forma adjustments through true-up dates of December 31, 2014 and January 1, 2015.
Ameren Missouri's rate request also seeks continued use of the FAC and the regulatory tracking mechanisms for storm costs, vegetation management and infrastructure inspection costs, pension and postretirement benefits, and uncertain income tax positions that the MoPSC authorized in earlier electric rate orders.
In October 2014, as part of this rate case proceeding, the MoOPC, the MIEC, and other parties filed a rate shift request that seeks to reduce Noranda’s electric rates with an offsetting increase in electric rates for Ameren Missouri’s other customers. Ameren Missouri supplies electricity to Noranda’s aluminum smelter in southeast Missouri under a 15-year agreement, that is subject to termination as early as 2020 upon at least five years notice by either party. Termination of the agreement by Ameren Missouri would require MoPSC approval.
In February 2015, the MoPSC staff recommended an increase to Ameren Missouri's annual revenues of $89 million based on a return on equity of 9.25%. In addition, the MoPSC staff opposed the continued use of the regulatory tracking mechanisms for storm costs and vegetation management and infrastructure inspection costs. The MoPSC staff also opposed the recovery of $36 million in fixed costs not previously recovered associated with the accounting authority order discussed below.
The MoPSC proceedings relating to the proposed electric service rate increase are ongoing and a decision by the MoPSC is expected by May 2015, with new rates effective by June 2015. Ameren Missouri cannot predict the level of any electric service rate change the MoPSC may approve or whether any rate increase that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and to earn a reasonable return on its investments when the rate changes go into effect.
FAC Prudence Review and Accounting Authority Order
In July 2013, the MoPSC issued an order with respect to its review of Ameren Missouri’s FAC calculation for the period from October 1, 2009, to May 31, 2011. 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 2009. As a result of the order, in 2013 Ameren Missouri recorded a pretax charge to earnings of $26 million, including $1 million for interest, for its estimated obligation to refund to its electric customers the earnings associated with these sales previously recognized 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 during the time period of March 1, 2009, to May 31, 2011, 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 accounting authority order that allowed Ameren Missouri to seek recovery of these fixed costs in an electric rate case. Ameren Missouri’s July 2014 electric rate case filing requested recovery of these fixed costs over five years. The MIEC and the MoOPC filed appeals of the MoPSC’s November 2013 accounting authority order with the Missouri Court of Appeals, Western District. In January 2015, the Missouri Court of Appeals, Western District upheld the MoPSC's order. Ameren Missouri has not recorded any potential revenue associated with this accounting authority order.
MEEIA Filing
In December 2014, Ameren Missouri filed an energy efficiency plan with the MoPSC under the MEEIA. This filing proposed a three-year plan that includes a portfolio of customer energy efficiency programs along with a cost recovery mechanism. If the plan is approved, beginning in January 2016, Ameren Missouri intends to invest $135 million over three years in the proposed customer energy efficiency programs. Ameren Missouri requested continued use of a MEEIA rider that allows it to collect from or refund to customers any difference in the actual amounts incurred and the amounts collected from customers for the MEEIA program costs and its lost revenues. In addition, Ameren Missouri requested incentives to earn additional revenues by achieving certain energy efficiency goals, including $25 million if 100% of its energy efficiency goals are achieved during the three-year period. Ameren Missouri must achieve at least 70% of its energy efficiency goals before it earns any incentive award.
Illinois
IEIMA
Under the provisions of the IEIMA, Ameren Illinois’ electric delivery service rates are subject to an annual revenue requirement reconciliation to its actual costs. Throughout each 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 reflected in customer rates 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, 2014, Ameren Illinois had recorded regulatory assets of $101 million and $65 million to reflect its expected 2014 and 2013 revenue requirement reconciliation adjustments, respectively, with interest. As of December 31, 2013, Ameren Illinois had recorded a $65 million regulatory liability to reflect its 2012 revenue requirement reconciliation adjustment, which was refunded, with interest, to customers during 2014.
In December 2014, the ICC issued an order in Ameren Illinois’ annual update filing approving a $204 million increase in Ameren Illinois’ electric delivery service revenue requirement beginning in January 2015. This update reflects an increase to the annual formula rate based on 2013 actual costs and expected net plant additions for 2014, an increase to include the 2013 revenue requirement reconciliation adjustment, which was recorded as a regulatory asset at December 31, 2014, and an increase resulting from the conclusion of the 2014 refund to customers for the 2012 revenue requirement reconciliation adjustment.
In February 2014, Ameren Illinois filed an appeal of the ICC's December 2013 annual formula rate order to the Appellate Court of the Fourth District of Illinois regarding the rate treatment of accumulated deferred income taxes related to the transfer of former Ameren Missouri electric assets located in Illinois to Ameren Illinois. Ameren Illinois withdrew this appeal in February 2015.
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. As a result of the ICC order, in 2013, Ameren and Ameren Illinois each recorded a pretax charge to earnings of $15 million relating to the partial disallowance of the debt premium costs. In the December 2014 order discussed above, the ICC allowed partial recovery from customers of certain previously disallowed debt premium costs. Accordingly, in 2014, Ameren and Ameren Illinois each recorded a pretax increase to earnings of $11 million to reflect the partial recovery of the debt premium costs. Ameren and Ameren Illinois recorded the effects of both orders to “Interest charges” with a corresponding offset to “Regulatory assets.”
2015 Natural Gas Delivery Service Rate Case
In January 2015, Ameren Illinois filed a request with the ICC seeking approval to increase its annual revenues for natural gas delivery service by $53 million. The request was based on a 10.25% return on common equity, a capital structure composed of 50% common equity, and a rate base of $1.2 billion. In an attempt to reduce regulatory lag, Ameren Illinois used a 2016 future test year in this proceeding. Included in the request was a proposal to implement a decoupling rider mechanism for residential and small nonresidential customers. The decoupling rider would ensure that changes in natural gas sales volumes do not affect Ameren Illinois' annual natural gas revenues for these rate classes.
A decision by the ICC in this proceeding is required by December 2015, with new rates expected to be effective in January 2016. Ameren Illinois cannot predict the level of any delivery service rate changes the ICC may approve, or whether the ICC will approve the decoupling rider, or whether any rate changes that may eventually be approved will be sufficient to enable Ameren Illinois to recover its costs and to earn a reasonable return on investments when the rate changes go into effect.
2013 Natural Gas Delivery Service Rate Order
In December 2013, the ICC issued a rate order that approved an increase in revenues for Ameren Illinois' natural gas delivery service of $32 million. The revenue increase was based on a 9.1% return on common 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 March 2014, Ameren Illinois filed with the Appellate Court of the Fourth District of Illinois an appeal of the allowed return on common equity included in the ICC's order and also appealed the rate treatment of accumulated deferred income taxes related to the transfer of former Ameren Missouri natural gas assets located in Illinois to Ameren Illinois. Ameren Illinois sought a 10.4% return on common equity in this rate case. In February 2015, Ameren Illinois withdrew its appeal solely as it related to the rate treatment of the accumulated deferred income taxes.
ATXI Transmission Project
ATXI's Spoon River project in northwest Illinois is a MISO-approved transmission line project with an expected cost of $150 million. In August 2014, ATXI made a filing with the ICC requesting a certificate of public convenience and necessity and project approval for the Spoon River project. A decision is expected from the ICC in 2015. A certificate of public convenience and necessity is required before ATXI can proceed with right-of-way acquisitions.
Federal
2011 Wholesale Distribution Rate Case
In January 2011, Ameren Illinois filed a request with the FERC to increase its annual revenues for electric delivery service to its wholesale customers. These wholesale distribution revenues are treated as a deduction from Ameren Illinois’ revenue requirement in retail rate filings with the ICC, with no material effect on net income. In March 2011, the FERC issued an order authorizing the proposed rates to take effect, subject to refund when the final rates are determined. In September 2014, the FERC issued an order that finalized rates and resulted in refunds due to the wholesale customers. In October 2014, Ameren Illinois refunded $24 million, including interest, to the wholesale customers and requested a rehearing on certain aspects of the order.
Ameren Illinois Electric Transmission Rate Refund
In July 2012, the FERC issued an order concluding that Ameren Illinois improperly included acquisition premiums, including 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.
Ameren Illinois submitted a refund report in November 2012 and concluded that no refund was warranted. Several wholesale customers filed a protest with the FERC regarding that conclusion. In June 2013, the 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.
In June 2014, the FERC issued an order that denied Ameren Illinois’ rehearing requests of the July 2012 order and the June 2013 order. Separately, in June 2014, the FERC issued an order establishing settlement procedures and, if necessary, hearing procedures regarding Ameren Illinois’ July 2013 refund report. In July 2014, Ameren Illinois filed an appeal of the FERC order denying rehearing of the July 2012 and June 2013 orders with the United States Court of Appeals for the District of Columbia Circuit. Also in July 2014, Ameren Illinois filed a request for rehearing with the FERC of its June 2014 order regarding the July 2013 refund report. In November 2014, the United States Court of Appeals for the District of Columbia issued an order suspending the appeal until the related FERC proceedings have been completed.
Ameren Illinois estimates the maximum pretax charge to earnings for this possible refund obligation through December 31, 2014, is $22 million. Ameren and Ameren Illinois recorded a current liability representing their estimate of the probable refund due to electric transmission customers based on the June 2014 order. If Ameren Illinois was to determine that a refund to its electric transmission customers in excess of the amount already recorded is probable, an additional charge to earnings would be recorded in the period in which that determination was made.
FERC Complaint Cases
In November 2013, a customer group filed a complaint case with the FERC seeking a reduction in the allowed base return on common equity for the FERC-regulated MISO transmission rate base under the MISO tariff to 9.15%. Currently, the FERC-allowed base return on common equity for MISO transmission owners is 12.38%. In October 2014, the FERC issued an order establishing settlement procedures and, if necessary, hearing procedures regarding the allowed base return on common equity. In January 2015, the settlement judge terminated settlement proceedings and the FERC scheduled the case for hearing proceedings, requiring an initial decision to be issued no later than November 30, 2015. As the original 15-month refund period for the November 2013 complaint case ended in February 2015, another customer complaint case was filed in February 2015. The February 2015 complaint case seeks a reduction in the allowed base return on common equity for the FERC-regulated MISO transmission rate base under the MISO tariff to 8.67%.
In October 2014, the FERC issued an order in a proceeding, in which the Ameren Companies were not involved, reducing the allowed base return on common equity for New England transmission owners from 11.14% to 10.57%, with rate incentives allowed up to 11.74%. The FERC order in the New England transmission owners’ case applied observable market data from October 2012 to March 2013 to determine the allowed base return on common equity. The FERC expects the evidence and the calculation used in the New England transmission owners’ case to guide its decision in the MISO complaint case discussed above. The FERC calculation will establish the allowed base return on common equity, which specifies a unique time period for each complaint case, and will require multiple inputs based on observable market data specific to the utility industry and broader macroeconomic data. In January 2015, the settlement judge for the MISO complaint case ordered that July 13, 2015, should be the cut-off date for the observable market data to be used in the calculation of the allowed base return on common equity. Based on the information in these orders, Ameren and Ameren Illinois recorded current liabilities representing their estimate of the required refunds from the refund effective date of November 12, 2013, through December 31, 2014. Ameren Missouri did not record a liability as of December 31, 2014, and does not expect that a reduction in the FERC-allowed base return on common equity for MISO transmission owners would be material to its results of operations, financial position, or liquidity.
In November 2014, we filed a request with the FERC to include an incentive adder of up to 50 basis points on the allowed base return on common equity for participation in an RTO, and we sought authorization to defer collection of it until after the issuance of the final order addressing the initial MISO complaint case discussed above. FERC approved the request to implement the incentive adder prospectively from January 6, 2015, and to defer collection of it until the issuance of the final order addressing the initial MISO complaint case.
Ameren Missouri Power Purchase Agreement with Entergy
Beginning in 2005, the FERC issued a series of orders addressing a complaint filed in 2001 by the Louisiana Public Service Commission 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 that expired August 31, 2009. In May 2012, the 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 “Operating Expenses – 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 November 2013, Entergy filed an appeal of the 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 Louisiana Public Service Commission appealed the FERC’s orders regarding Louisiana Public Service Commission’s complaint against Entergy Services, Inc. to the United States Court of Appeals for the District of Columbia Circuit. That court ordered further FERC proceedings regarding Louisiana Public Service Commission’s complaint. Ameren Missouri estimates that it could incur an additional expense of up to $8 million if the FERC's May 2012 order is overturned on appeal. Ameren Missouri believes that the likelihood of incurring any expense is not probable, and therefore no liability has been recorded as of December 31, 2014.
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 the Callaway site, and the NRC suspended review of the COL application. The suspended status of the COL application currently extends through the end of 2015.
Ameren Missouri estimates the total cost to obtain a COL for the Callaway site to be approximately $100 million. As of December 31, 2014, 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, the NRC does not extend the COL application suspended status, or if management concludes it is probable that the costs incurred will be disallowed in rates, a charge to earnings would be recognized in the period in which that determination is made.
Regulatory Assets and Liabilities
In accordance with authoritative accounting guidance regarding accounting for the effects of certain types of regulation, we 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. We may 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 our regulatory assets and regulatory liabilities at December 31, 2014 and 2013:
 
 
2014
 
2013
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Current regulatory assets:
 
 
 
 
 
 
 
 
 
 
 
 
 
Under-recovered FAC(a)(b)
 
$
128

 
$
—

 
$
128

 
 
$
104

 
$
—

 
$
104

Under-recovered Illinois electric power costs(c)
 
—

 
2

 
2

 
 
—

 
1

 
1

Under-recovered PGA(c)
 
—

 
20

 
20

 
 
—

 
1

 
1

MTM derivative losses(d)
 
32


42

 
74

 
 
14

 
36

 
50

Energy efficiency riders(e)

 
3

 
—

 
3

 
 
—

 
—

 
—

IEIMA revenue requirement reconciliation(a)(f)
 
—

 
65

 
65

 
 
—

 
—

 
—

FERC revenue requirement reconciliation(a)(g)

 
—

 
—

 
3

 
 
—

 
—

 
—

Total current regulatory assets
 
$
163

 
$
129

 
$
295

 
 
$
118

 
$
38

 
$
156

Noncurrent regulatory assets:
 
 
 
 
 
 
 
 
 
 
 
 
 
Pension and postretirement benefit costs(h)
 
$
148

 
$
275

 
$
423

 
 
$
44

 
$
140

 
$
184

Income taxes(i)
 
253

 
3

 
256

 
 
230

 
7

 
237

Asset retirement obligations(j)
 
—

 
5

 
5

 
 
—

 
5

 
5

Callaway costs(a)(k)
 
36

 
—

 
36

 
 
40

 
—

 
40

Unamortized loss on reacquired debt(a)(l)
 
72

 
80

 
152

 
 
77

 
74

 
151

Contaminated facilities costs(m)
 
—

 
251

 
251

 
 
—

 
271

 
271

MTM derivative losses(d)
 
14


144

 
158



8

 
118

 
126

Storm costs(n)
 
—

 
3

 
3

 
 
5

 
3

 
8

Demand-side costs before the MEEIA implementation(a)(o)
 
44

 
—

 
44

 
 
58

 
—

 
58

Workers’ compensation claims(p)
 
7

 
7

 
14

 
 
6

 
6

 
12

Credit facilities fees(q)
 
5

 
—

 
5

 
 
5

 
—

 
5

Common stock issuance costs(r)
 
2

 
—

 
2

 
 
4

 
—

 
4

Construction accounting for pollution control equipment(a)(s)
 
21

 
—

 
21

 
 
22

 
—

 
22

Solar rebate program(a)(t)
 
88

 
—

 
88

 
 
27

 
—

 
27

IEIMA revenue requirement reconciliation(a)(f)
 
—

 
101

 
101

 
 
—

 
65

 
65

FERC revenue requirement reconciliation(a)(g)
 
—

 
8

 
12

 
 
—

 
—

 
5

Other(u)
 
5

 
6

 
11

 
 
8

 
12

 
20

Total noncurrent regulatory assets
 
$
695

 
$
883

 
$
1,582

 
 
$
534

 
$
701

 
$
1,240

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

 
$
—

 
$
—

 
 
$
26

 
$
—

 
$
26

Over-recovered Illinois electric power costs(c)
 
—

 
26

 
26

 
 
—

 
51

 
51

Over-recovered PGA(c)
 
2

 
25

 
27

 
 
5

 
29

 
34

MTM derivative gains(d)
 
16

 
1

 
17


 
26

 
1

 
27

Wholesale distribution refund(v)
 
—

 
—

 
—

 
 
—

 
13

 
13

IEIMA revenue requirement reconciliation(f)
 
—

 
—

 
—

 
 
—

 
65

 
65

FERC revenue requirement reconciliation(g)
 
—

 
11

 
11

 
 
—

 
—

 
—

Refund reserves for FERC orders and audit findings(w)
 
—

 
21

 
25

 
 
—

 
—

 
—

Total current regulatory liabilities
 
$
18

 
$
84

 
$
106

 
 
$
57

 
$
159

 
$
216

Noncurrent regulatory liabilities:
 
 
 
 
 
 
 
 
 
 
 
 
 
Income taxes(x)
 
$
41

 
$
14

 
$
55

 
 
$
37

 
$
3

 
$
40

Uncertain tax positions tracker(y)
 
7

 
—

 
7

 
 
1

 
—

 
1

Removal costs(z)
 
886

 
643

 
1,529

 
 
828

 
610

 
1,438

Asset retirement obligation(j)
 
182

 
—

 
182

 
 
146

 
—

 
146

Bad debt riders(aa)
 
—

 
7

 
7

 
 
—

 
8

 
8

Pension and postretirement benefit costs tracker(ab)
 
24

 
—

 
24

 
 
15

 
—

 
15

Energy efficiency riders(e)
 
—

 
39

 
39

 
 
3

 
33

 
36

FERC revenue requirement reconciliation(g)
 
—

 
—

 
—

 
 
—

 
10

 
10

Other(ac)
 
7

 
—

 
7

 
 
11

 
—

 
11

Total noncurrent regulatory liabilities
 
$
1,147

 
$
703

 
$
1,850

 
 
$
1,041

 
$
664

 
$
1,705

(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)
The Ameren Missouri balance relates to the MEEIA. Beginning in January 2014, a MEEIA rider allowed Ameren Missouri to collect from or refund to customers any annual difference in the actual amounts incurred and the amounts collected from customers for the MEEIA program costs and its lost revenues. Under the MEEIA rider, collections from or refunds to customers occur one year after the program costs and lost revenues are incurred. The Ameren Illinois balance relates to a regulatory tracking mechanism to recover its electric and natural gas costs associated with developing, implementing, and evaluating customer energy efficiency and demand response programs. Any under-recovery or over-recovery will be collected from or refunded to customers over the 12 months following the plan year.
(f)
The difference between Ameren Illinois' annual revenue requirement calculated under the IEIMA's performance-based formula ratemaking framework and the revenue requirement included in customer rates for that year. Subject to ICC approval, these amounts will be collected from or refunded to customers within two years.
(g)
Ameren Illinois' and ATXI's annual revenue requirement reconciliation adjustments calculated pursuant to the FERC's electric transmission formula ratemaking framework. The under-recovery or over-recovery will be recovered from or refunded to customers within two years.
(h)
These costs are being amortized in proportion to the recognition of prior service costs (credits) and actuarial losses (gains) attributable to Ameren’s pension plan and postretirement benefit plans. See Note 11 – Retirement Benefits for additional information.
(i)
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.
(j)
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.
(k)
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.
(l)
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.
(m)
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.
(n)
Ameren Missouri's actual storm costs that exceed the normalized storm costs for rate purposes. As approved by the December 2012 MoPSC electric rate order, the 2006, 2007, and 2008 storm costs were amortized through December 2014. The Ameren Illinois balance includes 2013 storm costs deferred in accordance with the IEIMA. These costs are being amortized over a five-year period beginning in 2013.
(o)
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.The amortization period for costs incurred from August 2012 through December 2012 will be determined in the July 2014 electric rate case.
(p)
The period of recovery will depend on the timing of actual expenditures.
(q)
Ameren Missouri’s costs incurred to enter into and maintain the 2012 Missouri Credit Agreement. Additional costs were incurred in December 2014 to amend and restate the 2012 Missouri Credit Agreement. These costs are being amortized over the life of the credit facility, ending in December 2019, to construction work in progress, which will be depreciated when assets are placed into service.
(r)
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.
(s)
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 was included in customer rates. These costs will be amortized over the expected life of the Sioux energy center, which is currently through 2033.
(t)
Costs associated with Ameren Missouri's solar rebate program beginning in August 2012 to fulfill its renewable energy portfolio requirement. The amortization period for these costs will be three years, commencing with the effectiveness of Ameren Missouri's current July 2014 electric rate case.
(u)
The Ameren Illinois balance includes Ameren Illinois Merger integration and optimization costs, which are being 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. 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.
(v)
Estimated refund to wholesale electric customers as of December 31, 2013. See 2011 Wholesale Distribution Rate Case above.
(w)
Estimated refunds to transmission customers related to FERC orders and audit findings. In regards to the FERC orders, see Ameren Illinois Electric Transmission Rate Refund and FERC Complaint Cases above.
(x)
Unamortized portion of investment tax credits and federal excess deferred taxes. The unamortized portion of investment tax credits and the federal excess deferred taxes are being amortized over the expected life of the underlying assets.
(y)
The tracker is amortized over three years, beginning from the date the amounts are included in rates. See Note 13 - Income Taxes for additional information.
(z)
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.
(aa)
A regulatory tracking mechanism for the difference between the level of bad debt incurred by Ameren Illinois under GAAP and the level of such costs included in electric and natural gas rates. The over-recovery relating to 2012 was refunded to customers from June 2013 through May 2014. The over-recovery relating to 2013 is being refunded to customers from June 2014 through May 2015. The over-recovery relating to 2014 will be refunded to customers from June 2015 through May 2016.
(ab)
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 the July 2014 electric rate case.
(ac)
Balance 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 balance also includes a regulatory tracking mechanism at Ameren Missouri for the difference between the level of storm costs incurred in a particular year and the level of such costs built into rates. The amortization periods for these over-recoveries will be determined in the July 2014 electric rate case.
Ameren, 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, 2014 and 2013:
 
 
Ameren
Missouri(a)
 
Ameren
Illinois
 
Other
 
Ameren(a)
2014
 
 
 
 
 
 
 
 
Property and plant, at original cost:
 
 
 
 
 
 
 
 
Electric
 
$
17,052

 
$
6,517

 
$
344

 
$
23,913

Natural gas
 
431

 
1,854

 
—

 
2,285

 
 
17,483

 
8,371

 
344

 
26,198

Less: Accumulated depreciation and amortization
 
7,086

 
2,422

 
251

 
9,759

 
 
10,397

 
5,949

 
93

 
16,439

Construction work in progress:
 
 
 
 
 
 
 
 
Nuclear fuel in process
 
209

 
—

 
—

 
209

Other
 
261

 
216

 
299

 
776

Property and plant, net
 
$
10,867

 
$
6,165

 
$
392

 
$
17,424

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


(a)
Amounts in Ameren and Ameren Missouri include two CTs under separate capital lease agreements. The gross cumulative asset value of those agreements was $233 million and $228 million at December 31, 2014 and 2013, respectively. The total accumulated depreciation associated with the two CTs was $66 million and $56 million at December 31, 2014 and 2013, 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, 2014 and 2013, the carrying value of these debt securities was $294 million and $299 million, respectively.
The following table provides accrued capital and nuclear fuel expenditures at December 31, 2014, 2013, and 2012, which represent noncash investing activity excluded from the accompanying statements of cash flows:
 
Ameren(a)
 
Ameren
Missouri
 
Ameren
Illinois
Accrued capital expenditures:
 
 
 
 
 
2014
$
181

 
$
72

 
$
59

2013
175

 
74

 
86

2012
107

 
63

 
37

Accrued nuclear fuel expenditures:
 
 
 
 
 
2014
13

 
13

 
(b)

2013
8

 
8

 
(b)

2012
8

 
8

 
(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 December 11, 2014, each of the 2012 Credit Agreements was amended and restated. The amended and restated agreements extended the maturity dates of the 2012 Credit Agreements from November 14, 2017, to December 11, 2019, resulting in $2.1 billion of credit provided through the extended maturity date. The facilities continue to include 24 international, national, and regional lenders, with no single lender providing more than $115 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 (the amount being each borrower's "Borrowing Sublimit"):
 
 
2012 Missouri Credit Agreement
2012 Illinois
Credit Agreement
Ameren
 
$
700

$
500

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, Ameren Missouri, and Ameren Illinois, will mature and expire on December 11, 2019. 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 maturity date of such 2012 Credit Agreement. The principal amount of each revolving loan owed by Ameren Missouri or Ameren Illinois under the applicable 2012 Credit Agreement will be due and payable no later than the earlier of the maturity date or 364 days after the date of such loan.
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 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. The 2012 Credit Agreements provide for the issuance of letters of credit for the account of the borrowers up to a maximum of 25% of the aggregate initial commitment under the applicable 2012 Credit Agreement. The borrowers have received commitments from the lenders to issue letters of credit up to $100 million under each of the 2012 Credit Agreements. In addition, the issuance of letters of credit is subject to 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, issuance of letters of credit, loan funding under the Ameren money pool arrangements, and other short-term intercompany loan arrangements, or for paying fees and expenses incurred in connection with the 2012 Credit Agreements. Both 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 and the 2012 Illinois Credit Agreement are available to support issuances under Ameren Missouri's and Ameren Illinois' commercial paper programs, respectively. As of December 31, 2014, 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, 2014, was $1.4 billion.
Ameren, Ameren Missouri, and Ameren Illinois did not borrow under the 2012 Credit Agreements for the years ended December 31, 2014 and 2013.
Commercial Paper
The following table summarizes the borrowing activity and relevant interest rates under Ameren Missouri's and Ameren Illinois' commercial paper program, for the years ended December 31, 2014 and 2013:
 
 
Ameren (parent)
Ameren Missouri
Ameren Illinois
Ameren Consolidated
2014
 
 
 
 
 
 
Average daily commercial paper outstanding
 
$
423

 
$
110

$
165

$
639

Outstanding borrowings at period-end
 
585

 
97

32

714

Weighted-average interest rate
 
0.36
%
 
0.38
%
0.32
%
0.36
%
Peak commercial paper during period(a)
 
$
625

 
$
495

$
300

$
910

Peak interest rate
 
0.75
%
 
0.70
%
0.60
%
0.75
%
2013
 
 
 
 
 
 
Average daily commercial paper outstanding
 
$
54

 
$
—

$
—

$
54

Outstanding borrowings at period-end
 
368

 
—

—

368

Weighted-average interest rate
 
0.56
%
 
—
%
—
%
0.56
%
Peak commercial paper during period(a)
 
$
368

 
$
—

$
—

$
368

Peak interest rate
 
0.85
%
 
—
%
—
%
0.85
%


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 for borrowings and issuances of letters of credit. These include 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 obtainment of required regulatory authorizations. In addition, it is a condition for any Ameren Illinois borrowing that, at the time of and after giving effect to such borrowing, Ameren Illinois 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, 2014, the ratios of consolidated indebtedness to total consolidated capitalization, calculated in accordance with the provisions of the 2012 Credit Agreements, were 50%, 49%, and 47%, 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, under 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. However, the interest coverage requirement will only apply at such times as Ameren does not have a senior long-term unsecured credit rating of at least Baa3 from Moody's or BBB- from S&P. As of December 31, 2014, Ameren exceeded the rating requirements and the interest coverage requirement was not applicable. 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 $75 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 2012 Credit Agreement 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 constitute a default by Ameren Missouri or Ameren Illinois.
None of the Ameren Companies' credit agreements or financing agreements 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, 2014.
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 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 utility 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 utility money pool or remit funds from other external sources. The availability of funds is also determined by funding requirement limits established by regulatory authorizations. 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 utility money pool. The average interest rate for borrowing under the money pool for the year ended December 31, 2014, was 0.19% (2013 - 0.14%).
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, 2014, 2013, and 2012.
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, 2014 and 2013:
 
2014
 
2013
Ameren (Parent):
 
 
 
8.875% Senior unsecured notes due 2014
$
—

 
$
425

Less: Maturities due within one year
—

 
(425
)
Long-term debt, net
$
—

 
$
—

Ameren Missouri:
 
 
 
Senior secured notes:(a)
 
 
 
5.50% Senior secured notes due 2014
—

 
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

3.50% Senior secured notes due 2024
350

 
—

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)

 
(e)

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) due 2022
54

 
59

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

 
240

Total long-term debt, gross
4,005

 
3,764

Less: Unamortized discount and premium
(6
)
 
(7
)
Less: Maturities due within one year
(120
)
 
(109
)
Long-term debt, net
$
3,879

 
$
3,648

 
2014
 
2013
Ameren Illinois:
 
 
 
Senior secured notes:
 
 
 
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

3.25% Senior secured notes due 2025(g)
300

 
—

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

 
280

4.30% Senior secured notes due 2044(g)
250

 
—

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

 
32

5.70% 1994A Series due 2024(j)
(j)

 
36

5.95% 1993 Series C-1 due 2026(k)
—

 
35

5.70% 1993 Series C-2 due 2026(k)
—

 
8

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

 
17

5.40% 1998A Series due 2028(j)
—

 
19

5.40% 1998B Series due 2028(j)
—

 
33

Fair-market value adjustments
—

 
4

Total long-term debt, gross
2,246

 
1,863

Less: Unamortized discount and premium
(5
)
 
(7
)
Less: Maturities due within one year
—

 
—

Long-term debt, net
$
2,241

 
$
1,856

Ameren consolidated long-term debt, net
$
6,120

 
$
5,504

(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 senior secured notes currently outstanding, 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)
The interest rates, and the periods during which such rates apply, vary depending on our selection of defined rate modes. Maximum interest rates could reach 18% depending on the series of bonds. The average interest rates for 2014 and 2013 were as follows:
    
 
2014
 
2013
Ameren Missouri 1992 Series due 2022
0.10%
 
0.17%
Ameren Missouri 1998 Series A due 2033
0.26%
 
0.34%
Ameren Missouri 1998 Series B due 2033
0.27%
 
0.33%
Ameren Missouri 1998 Series C due 2033
0.26%
 
0.34%
Ameren Illinois 1993 Series B-1 due 2028
0.21%
 
0.14%

(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 Ameren Illinois could cause these notes to become unsecured at any time by redeeming the pollution control bonds 5.90% Series 1993 due 2023 (of which less than $1 million remains outstanding). Ameren Illinois may resecure these notes if it chooses.
(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 senior secured notes currently outstanding, we do not expect the mortgage bond lien protection associated with these notes to fall away until 2024.
(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. Less than $1 million principal amount of the bonds remain outstanding.
(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. Less than $1 million principal amount of the bonds remain outstanding.
(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, 2014:
 
 
 Ameren
Missouri(a)
 
 Ameren
Illinois(a)
 
Ameren
Consolidated
2015
 
$
120

 
$
—

 
$
120

2016
 
266

 
129

 
395

2017
 
431

 
250

 
681

2018
 
383

 
457

 
840

2019
 
581

 
—

 
581

Thereafter
 
2,224

 
1,410

 
3,634

Total
 
$
4,005

 
$
2,246

 
$
6,251

(a)
Excludes unamortized discount and premium of $6 million and $5 million at Ameren Missouri and Ameren Illinois, respectively.
All classes of Ameren Missouri’s and Ameren Illinois’ preferred stock are entitled to cumulative dividends, have voting rights, and are not subject to mandatory redemption. The preferred stock 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, which is redeemable, at the option of the issuer, at the prices shown below as of December 31, 2014 and 2013:
 
 
 
Redemption Price(per share)
 
2014
 
2013
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
In May 2014, Ameren (parent) repaid at maturity $425 million of its 8.875% senior unsecured notes, plus accrued interest. The notes were repaid with proceeds from commercial paper issuances.
Ameren filed a Form S-3 registration statement with the SEC in May 2014, authorizing the offering of 8.6 million additional shares of its common stock under DRPlus, which expires in May 2017. 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 October 2013, Ameren filed a Form S-8 registration statement with the SEC, 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.
In June 2012, Ameren, Ameren Missouri, and Ameren Illinois filed a Form S-3 shelf registration statement registering the issuance of an indeterminate amount of certain types of securities, which expires in June 2015.
From 2012 through 2014, Ameren shares for its DRPlus and its 401(k) plans were purchased in the open market.
Ameren Missouri
In April 2014, Ameren Missouri issued $350 million of 3.50% senior secured notes due April 15, 2024, with interest payable semiannually on April 15 and October 15 of each year, beginning October 15, 2014. Ameren Missouri received proceeds of $348 million, which were used to repay at maturity $104 million of its 5.50% senior secured notes due May 15, 2014 and to repay a portion of its short-term debt.
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.
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 after redemption.
In June 2014, Ameren Illinois issued $250 million of 4.30% senior secured notes due July 1, 2044, with interest payable semiannually on January 1 and July 1, beginning January 1, 2015. Ameren Illinois received proceeds of $246 million, which were used to repay a portion of its short-term debt.
In December 2014, Ameren Illinois issued $300 million of 3.25% senior secured notes due March 1, 2025, with interest payable semiannually on March 1 and September 1, beginning March 1, 2015. Ameren Illinois received proceeds of $298 million, which were used to repay a portion of its short-term debt.
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, beginning June 15, 2014. Ameren Illinois received net proceeds of $276 million. The proceeds were used, together with other available cash, to repay at maturity $150 million of its 8.875% senior secured notes due December 15, 2013, and to repay its short-term debt.
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, dividend coverage ratios, and bonds and preferred stock issuable as of December 31, 2014, at an assumed interest rate of 5% and dividend rate of 6%.
 
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
4.3

$
3,605

  
>2.5
115.1

$
2,568

Ameren Illinois
>2.0
6.4

3,358

(d) 
>1.5
2.7

208

(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 $832 million and $204 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 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.” The 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 the FERC to maintain a minimum 30% ratio of common stock equity to total capitalization. As of December 31, 2014, Ameren Illinois’ ratio of common stock equity to total capitalization was 53%.
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, 2014, 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, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
 
Ameren:(a)
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
34

 
$
37

 
$
36

 
Interest income on industrial development revenue bonds
27

 
27

 
28

 
Interest income
10

(b) 
3

 
4

(d) 
Other
8

(c) 
2

 
2

 
Total miscellaneous income
$
79

 
$
69

 
$
70

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
10

 
$
12

 
$
24

(e) 
Other
12

 
14

 
13

 
Total miscellaneous expense
$
22

 
$
26

 
$
37

 
Ameren Missouri:
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
32

 
$
31

 
$
31

 
Interest income on industrial development revenue bonds
27

 
27

 
28

 
Interest income
1

 
—

 
4

(d) 
Total miscellaneous income
$
60

 
$
58

 
$
63

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
6

 
$
4

 
$
9

 
Other
6

 
7

 
5

 
Total miscellaneous expense
$
12

 
$
11

 
$
14

 
Ameren Illinois:
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
2

 
$
6

 
$
5

 
Interest income
7

(b) 
2

 
—

 
Other
8

(c) 
2

 
2

 
Total miscellaneous income
$
17

 
$
10

 
$
7

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
4

 
$
4

 
$
11

(e) 
Other
4

 
5

 
6

 
Total miscellaneous expense
$
8

 
$
9

 
$
17

 
(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
Includes Ameren Illinois' interest income received in 2014 relating to the 2013 and 2014 IEIMA revenue requirement reconciliation regulatory assets.
(c)
Includes Ameren Illinois' income earned in 2014 from customer-requested construction.
(d)
Includes Ameren Missouri's interest income 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.
(e)
Includes Ameren Illinois' one-time $7.5 million contribution to the Illinois Science and Energy Innovation Trust pursuant to the IEIMA as a result of Ameren Illinois' participation in the electric delivery formula ratemaking process.
Derivative Financial Instruments
DERIVATIVE FINANCIAL INSTRUMENTS
DERIVATIVE FINANCIAL INSTRUMENTS
We use derivatives to manage the risk of changes in market prices for natural gas, power, and uranium, as well as the risk of changes in rail transportation surcharges through fuel oil hedges. 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, 2014 and 2013. As of December 31, 2014, these contracts ran through October 2017, October 2019, May 2032, and October 2016 for fuel oils, natural gas, power, and uranium, respectively.
  
Quantity (in millions, except as indicated)
 
2014
2013
Commodity
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Fuel oils (in gallons)(a)
50
(b)
50
66
(b)
66
Natural gas (in mmbtu)
28
108
136
28
108
136
Power (in megawatthours)
1
11
12
3
11
14
Uranium (pounds in thousands)
332
(b)
332
796
(b)
796

(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. We believe derivative losses and gains 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, 2014 and 2013, 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 a 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 commodity contracts, none of which were designated as hedging instruments, as of December 31, 2014 and 2013:
 
Balance Sheet Location
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2014
 
 
 
 
 
 
 
Fuel oils
Other current assets
$
2

$
—

$
2

Natural gas
Other current assets
 
1

 
1

 
2

Power
Other current assets
 
15

 
—

 
15

 
Total assets
$
18

$
1

$
19

Fuel oils
Other current liabilities
$
22

$
—

$
22

 
Other deferred credits and liabilities
 
7

 
—

 
7

Natural gas
MTM derivative liabilities
 
(a)

 
31

 
(a)

 
Other current liabilities
 
6

 
—

 
37

 
Other deferred credits and liabilities
 
6

 
13

 
19

Power
MTM derivative liabilities
 
(a)

 
11

 
(a)

 
Other current liabilities
 
3

 
—

 
14

 
Other deferred credits and liabilities
 
—

 
131

 
131

Uranium
Other current liabilities
 
2

 
—

 
2

 
Total liabilities
$
46

$
186

$
232

2013
 
 
 
 
 
 
 
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

Fuel oils
Other current liabilities
$
2

$
—

$
2

 
Other deferred credits and liabilities
 
1

 
—

 
1

Natural gas
MTM derivative liabilities
 
(a)

 
27

 
(a)

 
Other current liabilities
 
5

 
—

 
32

 
Other deferred credits and liabilities
 
6

 
19

 
25

Power
MTM derivative liabilities
 
(a)

 
9

 
(a)

 
Other current liabilities
 
4

 
—

 
13

 
Other deferred credits and liabilities
 
—

 
99

 
99

Uranium
Other current liabilities
 
5

 
—

 
5

 
Other deferred credits and liabilities
 
1

 
—

 
1

 
Total liabilities
$
24

$
154

$
178

(a)
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, 2014 and 2013:
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2014
 
 
 
 
 
 
Fuel oils derivative contracts(a)
$
(29
)
$
—

$
(29
)
Natural gas derivative contracts(b)
 
(11
)
 
(43
)
 
(54
)
Power derivative contracts(c)
 
12

 
(142
)
 
(130
)
Uranium derivative contracts(d)
 
(2
)
 
—

 
(2
)
2013
 
 
 
 
 
 
Fuel oils derivative contracts
$
2

$
—

$
2

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

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

 
(6
)

(a)
Represents net losses associated with fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s rail transportation surcharges for coal through December 2017. Current losses deferred as regulatory assets include $21 million and $21 million at Ameren and Ameren Missouri, 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 October 2018 at Ameren Illinois. Current gains deferred as regulatory liabilities include $2 million, $1 million, and $1 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively. Current losses deferred as regulatory assets include $37 million, $6 million, and $31 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively.
(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. Current gains deferred as regulatory liabilities include $15 million and $15 million at Ameren and Ameren Missouri, respectively. Current losses deferred as regulatory assets include $14 million, $3 million, and $11 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively.
(d)
Represents net losses associated with uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri's uranium requirements through December 2016. Current losses deferred as regulatory assets include $2 million and $2 million at Ameren and Ameren Missouri, 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 netting arrangements, and reporting daily exposure to senior management.
We believe that entering into master netting arrangements 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 netting arrangements: (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 netting arrangements allow the counterparties to net settle sale and purchase transactions. Further, collateral requirements are calculated at the master netting arrangement level by counterparty.
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, 2014 and 2013:
 
 
 
 
Gross Amounts Not Offset on the Balance Sheet
 
 
Commodity Contracts Eligible to be Offset
 
Gross Amounts Recognized on the Balance Sheet
 
Derivative Instruments
 
Cash Collateral Received/Posted(a)
 
Net
Amount
2014
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
$
18

$
5

$
—

$
13

Ameren Illinois
 
1

 
—

 
—

 
1

Ameren
$
19

$
5

$
—

$
14

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
$
46

$
5

$
5

$
36

Ameren Illinois
 
186

 
—

 
—

 
186

Ameren
$
232

$
5

$
5

$
222

2013
 
 
 
 
 
 
 
 
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

(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 NPNS and other accrual contracts. As of December 31, 2014, if counterparty groups were to fail completely to perform on contracts, Ameren, Ameren Missouri, and Ameren Illinois' maximum exposure was $5 million, $5 million, and $- million, respectively. The potential loss on counterparty exposures is reduced by the application of master netting arrangements and collateral held, to the extent of reducing the exposure to zero. As of December 31, 2014, the potential loss after consideration of the application of master netting arrangements and collateral held for Ameren, Ameren Missouri, and Ameren Illinois was $5 million, $5 million, and $- 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, 2014, 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 netting arrangements assuming (1) the credit risk-related contingent features underlying these arrangements were triggered on December 31, 2014, 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)
Ameren Missouri
$
96

 
$
4

 
$
88

Ameren Illinois
74

 
—

 
71

Ameren
$
170

 
$
4

 
$
159

(a)
Prior to consideration of master netting arrangements and including NPNS and other accrual contract exposures.
(b)
As collateral requirements with certain counterparties are based on master netting arrangements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such arrangements.
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, 2014:
 
 
Fair Value
 
 
 
 
Weighted
 
 
Assets
Liabilities
 
Valuation Technique(s)
Unobservable Input
Range
Average
Level 3 Derivative asset and liability – commodity contracts(a):
 
 
 
Ameren
Fuel oils
$
2

$
(8
)
 
Option model
Volatilities(%)(b)
3 - 39
32
 
 
 
 
 
Discounted cash flow
Ameren Missouri credit risk(%)(b)(c)
0.43
(d)
 
 
 
 
 
 
Escalation rate(%)(e)(f)
5
(d)
 
Natural Gas
1

(2
)
 
Option model
Volatilities(%)(b)
31 - 144
63
 



 

Nodal basis($/mmbtu)(e)
(0.40) - 0
(0.20)
 



 
Discounted cash flow
Nodal basis($/mmbtu)(e)
(0.40) - 0.10
(0.20)
 



 

Counterparty credit risk(%)(b)(c)
0.43 - 13
3
 



 

Ameren Missouri and Ameren Illinois credit risk(%)(b)(c)
0.43
(d)
 
Power(g)
11

(144
)
 
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(h)
27 - 50
32
 
 
 
 
 
 
Estimated auction price for FTRs($/MW)(e)
(1,833) - 2,743
171
 
 
 
 
 
 
Nodal basis($/MWh)(e)
(6) - 0
(2)
 
 
 
 
 
 
Counterparty credit risk(%)(b)(c)
0.26
(d)
 
 
 
 
 
 
Ameren Missouri and Ameren Illinois credit risk(%)(b)(c)
0.43
(d)
 
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(e)
4 - 5
4
 
 
 
 
 
 
Escalation rate(%)(e)(i)
0 - 1
1
 
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(e)
5 - 7
6
 
Uranium
—

(2
)
 
Discounted cash flow
Average forward uranium pricing($/pound)(e)
35 - 40
36
Ameren Missouri
Fuel oils
$
2

$
(8
)
 
Option model
Volatilities(%)(b)
3 - 39
32
 
 
 
 
 
Discounted cash flow
Ameren Missouri credit risk(%)(b)(c)
0.43
(d)
 
 
 
 
 
 
Escalation rate(%)(e)(f)
5
(d)
 
Natural Gas
—

(1
)
 
Option model
Volatilities(%)(b)
31 - 144
53
 



 

Nodal basis($/mmbtu)(e)
(0.40) - 0
(0.30)
 



 
Discounted cash flow
Nodal basis($/mmbtu)(e)
(0.10)
(d)
 



 

Counterparty credit risk(%)(b)(c)
0.57 - 13
5
 



 

Ameren Missouri credit risk(%)(b)(c)
0.43
(d)
 
Power(g)
11

(2
)
 
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(b)
27 - 50
32
 
 
 
 
 
 
Estimated auction price for FTRs($/MW)(e)
(1,833) - 2,743
171
 
 
 
 
 
 
Counterparty credit risk(%)(b)(c)
0.26
(d)
 
 
 
 
 
 
Ameren Missouri credit risk(%)(b)(c)
0.43
(d)
 
Uranium
—

(2
)
 
Discounted cash flow
Average forward uranium pricing($/pound)(e)
35 - 40
36
Ameren Illinois
Natural Gas
$
1

$
(1
)
 
Option model
Volatilities(%)(b)
50 - 144
94
 



 

Nodal basis($/mmbtu)(e)
(0.10) - 0
(0.10)
 



 
Discounted cash flow
Nodal basis($/mmbtu)(e)
(0.40) - 0.10
(0.20)
 



 

Counterparty credit risk(%)(b)(c)
0.43 - 2
0.83
 



 

Ameren Illinois credit risk(%)(b)(c)
0.43
(d)
 
 
Fair Value
 
 
 
 
Weighted
 
 
Assets
Liabilities
 
Valuation Technique(s)
Unobservable Input
Range
Average
 
Power(g)
—

(142
)
 
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(e)
27 - 38
32
 
 
 
 
 
 
Nodal basis($/MWh)(e)
(6) - 0
(2)
 
 
 
 
 
 
Ameren Illinois credit risk(%)(b)(c)
0.43
(d)
 
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(e)
4 - 5
4
 
 
 
 
 
 
Escalation rate(%)(e)(i)
0 - 1
1
 
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(e)
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 lower (higher) fair value measurement.
(c)
Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(d)
Not applicable.
(e)
Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(f)
Escalation rate applies to fuel oil prices 2017 and beyond.
(g)
Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2018. Valuations beyond 2018 use fundamentally modeled pricing by month for peak and off-peak demand.
(h)
The balance at Ameren is comprised of Ameren Missouri and Ameren Illinois power contracts, which respond differently to unobservable input changes due to their opposing positions. As such, refer to the power sensitivity analysis for each company above.
(i)
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, 2013:
 
 
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)
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 Missouri and 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
 
Uranium
—

(6
)
 
Discounted cash flow
Average forward uranium 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 forward uranium 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 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.
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. No gains or losses related to valuation adjustments for counterparty default risk were recorded at Ameren, Ameren Missouri, or Ameren Illinois in 2014, 2013 or 2012. At December 31, 2014, the counterparty default risk liability valuation adjustment related to derivative contracts totaled $1 million, less than $1 million, and $1 million, for Ameren, Ameren Missouri, and Ameren Illinois, respectively. 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.
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, 2014:
 
 
 
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
 
$
—

 
$
—

 
$
2

 
$
2

 
 
Natural gas
 
—

 
1

 
1

 
2

 
 
Power
 
—

 
4

 
11

 
15

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
5

 
$
14

 
$
19

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
364

 
—

 
—

 
364

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
63

 
—

 
63

 
 
Municipal bonds
 
—

 
2

 
—

 
2

 
 
U.S. treasury and agency securities
 
—

 
102

 
—

 
102

 
 
Asset-backed securities
 
—

 
10

 
—

 
10

 
 
Other
 
—

 
5

 
—

 
5

 
 
Total nuclear decommissioning trust fund
 
$
365

 
$
182

 
$
—

 
$
547

(b) 
 
Total Ameren
 
$
365

 
$
187

 
$
14

 
$
566

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

 
$
—

 
$
2

 
$
2

 
 
Natural gas
 
—

 
1

 
—

 
1

 
 
Power
 
—

 
4

 
11

 
15

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
5

 
$
13

 
$
18

 
 
 
 
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
 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
364

 
—

 
—

 
364

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
63

 
—

 
63

 
 
Municipal bonds
 
—

 
2

 
—

 
2

 
 
U.S. treasury and agency securities
 
—

 
102

 
—

 
102

 
 
Asset-backed securities
 
—

 
10

 
—

 
10

 
 
Other
 
—

 
5

 
—

 
5

 
 
Total nuclear decommissioning trust fund
 
$
365

 
$
182

 
$
—

 
$
547

(b) 
 
Total Ameren Missouri
 
$
365

 
$
187

 
$
13

 
$
565

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

 
$
—

 
$
1

 
$
1

 
Liabilities:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
21

 
$
—

 
$
8

 
$
29

 
 
Natural gas
 
1

 
53

 
2

 
56

 
 
Power
 
—

 
1

 
144

 
145

 
 
Uranium
 
—

 
—

 
2

 
2

 
 
Total Ameren
 
$
22

 
$
54

 
$
156

 
$
232

 
Ameren Missouri
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
21

 
$
—

 
$
8

 
$
29

 
 
Natural gas
 
1

 
10

 
1

 
12

 
 
Power
 
—

 
1

 
2

 
3

 
 
Uranium
 
—

 
—

 
2

 
2

 
 
Total Ameren Missouri
 
$
22

 
$
11

 
$
13

 
$
46

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

 
$
43

 
$
1

 
$
44

 
 
Power
 
—

 
—

 
142

 
142

 
 
Total Ameren Illinois
 
$
—

 
$
43

 
$
143

 
$
186

 
(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 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

 
 
 
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
 
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 summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the year ended December 31, 2014:
  
 
Net Derivative Commodity Contracts
  
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
5

$
(a)

$
5

Realized and unrealized gains (losses) included in regulatory assets/liabilities:
 
(9
)
 
(a)

 
(9
)
Settlements
 
(2
)
 
(a)

 
(2
)
Ending balance at December 31, 2014
$
(6
)
$
(a)

$
(6
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014
$
(6
)
$
(a)

$
(6
)
Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
—

$
—

$
—

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

 
—

 
1

 
1

Purchases
 
—

 
(2
)
 
(2
)
Sales
 
(1
)
 
—

 
(1
)
Settlements
 
—

 
1

 
1

Ending balance at December 31, 2014
$
(1
)
$
—

$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014
$
—

$
2

$
2

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
19

$
(108
)
$
(89
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 
(14
)
 
(39
)
 
(53
)
Purchases
 
34

 
—

 
34

Sales
 
(1
)
 
—

 
(1
)
Settlements
 
(29
)
 
5

 
(24
)
Ending balance at December 31, 2014
$
9

$
(142
)
$
(133
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014
$
—

$
(43
)
 $
(43
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
(6
)
$
(a)

$
(6
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 
(1
)
 
(a)

 
(1
)
Settlements
 
5

 
(a)

 
5

Ending balance at December 31, 2014
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014
$
(1
)
$
(a)

$
(1
)
(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 for the year ended December 31, 2013:
  
 
Net Derivative Commodity Contracts
  
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
5

$
(a)

$
5

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
)
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
)
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
)
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.
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 between Level 2 and Level 3 for power derivatives were primarily caused by changes in availability of financial trades observable on electronic exchanges between the periods. 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, 2014 and 2013, there were no transfers between Level 1 and Level 2 related to derivative commodity contracts. For the year ended December 31, 2014, there were no transfers between Level 2 and Level 3 related to derivative commodity contracts. For the year ended December 31, 2013, there were $(3) million of transfers out of Level 2 into Level 3 and $4 million of transfers into Level 2 out of Level 3 related to power contracts at Ameren and Ameren Missouri.
See Note 11 – Retirement Benefits for the fair value hierarchy tables detailing Ameren’s pension and postretirement plan assets as of December 31, 2014, as well as a table summarizing the changes in Level 3 plan assets during 2014.
The Ameren Companies’ carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments. They 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, 2014 and 2013:
  
2014
 
2013
  
Carrying Amount
 
Fair Value
 
Carrying Amount
 
Fair Value
Ameren:(a)
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
6,240

 
$
7,135

 
$
6,038

 
$
6,584

Preferred stock
142

 
122

 
142

 
118

Ameren Missouri:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
3,999

 
$
4,518

 
$
3,757

 
$
4,124

Preferred stock
80

 
73

 
80

 
71

Ameren Illinois:
 
 
 
 
 
 
 
Long-term debt (including current portion)
$
2,241

 
$
2,517

 
$
1,856

 
$
2,028

Preferred stock
62

 
49

 
62

 
47

(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, 2014, and 2013. 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, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Proceeds from sales and maturities
$
391

 
$
196

 
$
384

Gross realized gains
7

 
7

 
6

Gross realized losses
2

 
5

 
2


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, 2014 and 2013:
Security Type
Cost
 
Gross Unrealized Gain
 
Gross Unrealized Loss
 
Fair Value
2014
 
 
 
 
 
 
 
Debt securities
$
175

 
$
7

$
(a)

 
$
182

Equity securities
138

 
230

 
4

 
364

Cash
1

 
—

 
—

 
1

Other(b)
2

 
—

 
—

 
2

Total
$
316

 
$
237

$
4

 
$
549

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

(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, 2014:
 
Cost
 
Fair Value
Less than 5 years
$
98

 
$
99

5 years to 10 years
41

 
42

Due after 10 years
36

 
41

Total
$
175

 
$
182


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, 2014:
  
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
$
28

$
(a)

 
 
$
8

$
(a)

 
$
36

$
(a)

Equity securities
6

 
1

 
 
5

 
3

 
11

 
4

Total
$
34

$
1

 
 
$
13

$
3

 
$
47

$
4

(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 and sold by those plants. The NWPA also requires the DOE annually 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 had historically collected one mill from its electric customers for each kilowatthour of electricity that it generates and sells from its Callaway energy center. However, as described below, Ameren Missouri has suspended collection of this fee.
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 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, potentially co-located with the pilot facility on a geologic repository. The plan also proposes to begin operation of a permanent geological repository by 2048.
Because the federal government is not meeting its disposal obligation, 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. In November 2013, the court ordered the DOE to submit a proposal to the United States Congress to reduce the fee to zero. In January 2014, the DOE submitted that proposal, and it became effective in May 2014. Since the nuclear waste fee was previously included in Ameren Missouri’s FAC, the cost reduction will be passed on to electric utility customers with no material effect on Ameren’s or Ameren Missouri’s net income.
As a result of the DOE's failure to begin to dispose of spent nuclear fuel from commercial nuclear energy centers 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. The lawsuit sought reimbursement for the cost of reracking the Callaway energy center’s spent fuel pool, for certain NRC fees, and for Missouri ad valorem taxes that Ameren Missouri would not have incurred had the DOE performed its contractual obligations. The parties entered into a settlement agreement that provides for annual recovery of additional spent fuel storage and related costs incurred from 2010 through 2016, with the ability to extend the recovery period as mutually agreed upon by the parties. Included in these reimbursements are costs related to a dry spent fuel storage facility that Ameren Missouri is constructing at its Callaway energy center. Ameren Missouri intends to begin transferring spent fuel assemblies to this facility in 2015. Ameren Missouri will continue to apply for reimbursement from the DOE for the cost to construct and operate 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 upon which the NRC has historically relied 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. As a result, the NRC stated that it would not issue licenses dependent on the vacated rules until it appropriately addressed the court's remand. In October 2014, after it completed the required environmental analysis, the NRC lifted its suspension on final licensing decisions. In February 2015, the staff of the NRC issued its recommendation that the NRC approve Ameren Missouri's application for a 20-year renewal of the Callaway energy center's operating license.
Electric utility rates currently 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. Amounts collected from customers are deposited into the external nuclear decommissioning trust fund to provide for the Callaway energy center’s decommissioning. 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. Annual decommissioning costs of $7 million are included in the costs of service used to establish electric rates for Ameren Missouri's customers. 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 was filed with the MoPSC in September 2011. The MoPSC has authorized a delay of the 2014 cost study and funding analysis filing until 2015 pending the outcome of Ameren Missouri’s operating license extension application under review by the NRC. Following the NRC’s decision regarding Ameren Missouri’s operating license extension application, an updated cost study and a revised funding analysis will be filed. Rates charged to customers will be adjusted accordingly, as approved by the MoPSC, to reflect the operating license extension application decision, the updated cost study and the revised funding analysis. 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 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. Only Ameren subsidiaries participate in the plans listed above.
In December 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, and who were included in the Ameren Retiree Medical Plan and the Ameren Group Life Insurance Plan.
Ameren’s unfunded obligation under its pension and other postretirement benefit plans was $710 million and $461 million as of December 31, 2014, and December 31, 2013, 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 factor contributing to the increase in the unfunded obligation during 2014 was a 75 basis point decrease in the pension and other postretirement benefit plan discount rates used to determine the present value of the obligation. The offset to the increase in the unfunded obligation was primarily an increase to "Regulatory assets" on Ameren's, Ameren Missouri's, and Ameren Illinois' 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, 2014 and 2013:
 
2014

2013

Ameren(a)
$
710

$
461

Ameren Missouri
277

191

Ameren Illinois
278

159

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Ameren recognizes the underfunded 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 Ameren's pension and postretirement benefit plans as of December 31, 2014 and 2013. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 2014 and 2013, that have not been recognized in net periodic benefit costs.
  
2014
 
2013
  
Pension Benefits(a)
 
Postretirement
Benefits(a)
 
Pension Benefits(a)
 
Postretirement
Benefits(a)
Accumulated benefit obligation at end of year
$
4,176

$
(b)

 
$
3,698

$
(b)

Change in benefit obligation:
 
 
 
 
 
 
 
Net benefit obligation at beginning of year
$
3,900

$
1,096

 
$
4,051

$
1,157

Service cost
79

 
19

 
91

 
22

Interest cost
183

 
50

 
163

 
46

Participant contributions
—

 
16

 
—

 
16

Actuarial (gain) loss
462

 
84

 
(207
)
 
(76
)
Curtailment gain(c)
—

 
—

 
—

 
(3
)
Settlement(d)
—

 
—

 
—

 
(5
)
Benefits paid
(214
)
 
(65
)
 
(198
)
 
(64
)
Federal subsidy on benefits paid
(b)

 
3

 
(b)

 
3

Net benefit obligation at end of year
4,410

 
1,203

 
3,900

 
1,096

Change in plan assets:
 
 
 
 
 
 
 
Fair value of plan assets at beginning of year
3,461

 
1,074

 
3,127

 
938

Actual return on plan assets
448

 
75

 
376

 
156

Employer contributions
99

 
6

 
156

 
25

Federal subsidy on benefits paid
(b)

 
3

 
(b)

 
3

Participant contributions
—

 
16

 
—

 
16

Benefits paid
(214
)
 
(65
)
 
(198
)
 
(64
)
Fair value of plan assets at end of year
3,794

 
1,109

 
3,461

 
1,074

Funded status – deficiency
616

 
94

 
439

 
22

Accrued benefit cost at December 31
$
616

$
94

 
$
439

$
22

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

$
—

 
$
—

$
(9
)
Current liability(f)
3

 
2

 
3

 
1

Noncurrent liability
613

 
92

 
436

 
30

Net liability recognized
$
616

$
94

 
$
439

$
22

Amounts recognized in regulatory assets consist of:
 
 
 
 
 
 
 
Net actuarial (gain) loss
$
452

$
(7
)
 
$
282

$
(71
)
Prior service cost (credit)
(6
)
 
(16
)
 
(7
)
 
(20
)
Amounts (pretax) recognized in accumulated OCI consist of:
 
 
 
 
 
 
 
Net actuarial (gain) loss
29

 
(5
)
 
17

 
(12
)
Prior service cost (credit)
—

 
(1
)
 
—

 
(1
)
Total
$
475

$
(29
)
 
$
292

$
(104
)
(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 additional 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 additional 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, 2014 and 2013:
  
Pension Benefits
 
Postretirement Benefits
  
2014
 
2013
 
2014
 
2013
Discount rate at measurement date
4.00
%
 
4.75
%
 
4.00
%
 
4.75
%
Increase in future compensation
3.50

 
3.50

 
3.50

 
3.50

Medical cost trend rate (initial)
(a)

 
(a)

 
5.00

 
5.00

Medical cost trend rate (ultimate)
(a)

 
(a)

 
5.00

 
5.00

Years to ultimate rate
(a)

 
(a)

 
—

 
—


(a)
Not applicable
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. The settlement portfolio of bonds is selected from a pool of more than 700 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. In addition, during 2014, Ameren adopted the Society of Actuaries 2014 Mortality Tables Report and Mortality Improvement Scale. The updated mortality tables assume increasing life expectancies for our employees and retirees, which resulted in an increase to our pension and other postretirement benefit obligations.
Funding
Pension benefits are based on the employees’ years of service and compensation. Ameren’s pension plans are 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, 2014, its investment performance in 2014, and its pension funding policy, Ameren expects to make annual contributions of $25 million to $115 million in each of the next five years, with aggregate estimated contributions of $290 million. We expect Ameren Missouri’s and Ameren Illinois’ portion of the future funding requirements to be 41% and 40%, 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 2014, 2013, and 2012:
  
Pension Benefits
 
Postretirement Benefits
  
2014
 
2013
 
2012
 
2014
 
2013
 
2012
Ameren Missouri
$
41

 
$
60

 
$
52

 
$
3

 
$
10

 
$
9

Ameren Illinois
39

 
50

 
46

 
2

 
11

 
35

Other
19

 
46

 
30

 
1

 
4

 
1

Ameren(a)
99

 
156

 
128

 
6

 
25

 
45

(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 that 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; and second, to maximize total return on plan assets and to minimize expense volatility consistent with its tolerance for risk. Ameren delegates the task of investment management to specialists in each asset class. As appropriate, Ameren provides each 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 2015. No plan assets are expected to be returned to Ameren during 2015.
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 2015 and our pension and postretirement plans’ asset categories as of December 31, 2014 and 2013:
Asset
Category
Target Allocation
2015
 
Percentage of Plan Assets at December  31,
2014
 
2013
Pension Plan:
 
 
 
 
 
Cash and cash equivalents
0% - 5%
 
2
%
 
2
%
Equity securities:
 
 
 
 
 
U.S. large-capitalization
29% - 39%
 
34
%
 
36
%
U.S. small- and mid-capitalization
2% - 12%
 
7
%
 
8
%
International and emerging markets
9% - 19%
 
12
%
 
14
%
Total equity
50% - 60%
 
53
%
 
58
%
Debt securities
35% - 45%
 
41
%
 
36
%
Real estate
0% -   9%  
 
4
%
 
4
%
Private equity
0% -   4%  
 
(a)

 
(a)

Total
 
 
100
%
 
100
%
Postretirement Plans:
 
 
 
 
 
Cash and cash equivalents
0% - 10%
 
4
%
 
4
%
Equity securities:
 
 
 
 
 
U.S. large-capitalization
33% - 43%
 
40
%
 
41
%
U.S. small- and mid-capitalization
3% - 13%
 
7
%
 
8
%
International
10% - 20%
 
13
%
 
14
%
Total equity
55% - 65%
 
60
%
 
63
%
Debt securities
30% - 40%
 
36
%
 
33
%
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 is spread among nine different limited partnerships, with invested capital ranging from $0.1 million to $5 million in 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, 2014. The fair value of an asset is the amount that would be received upon its 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, 2014:
 
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
$
—

 
$
38

 
$
—

 
$
38

Equity securities:
 
 
 
 
 
 
 
U.S. large-capitalization
—

 
1,331

 
—

 
1,331

U.S. small- and mid-capitalization
270

 
—

 
—

 
270

International and emerging markets
134

 
360

 
—

 
494

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
1,026

 
—

 
1,026

Municipal bonds
—

 
175

 
—

 
175

U.S. treasury and agency securities
6

 
366

 
—

 
372

Other
—

 
31

 
—

 
31

Real estate
—

 
—

 
147

 
147

Private equity
—

 
—

 
13

 
13

Derivative assets
1

 
—

 
—

 
1

Total
$
411

 
$
3,327

 
$
160

 
$
3,898

Less: Medical benefit assets at December 31(a)
 
 
 
 
 
 
(125
)
Plus: Net receivables at December 31(b)
 
 
 
 
 
 
21

Fair value of pension plans assets at year end
 
 
 
 
 
 
$
3,794

(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, 2013:
 
Quoted Prices in
Active Markets for
Identified Assets or Liabilities
(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 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, 2014 and 2013:
 
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,
2014:
 
 
 
 
 
 
 
 
 
 
 
Real estate
$
131

 
$
11

 
$
—

 
$
5

 
$
—

 
$
147

Private equity
15

 
(9
)
 
10

 
(3
)
 
—

 
13

2013:
 
 
 
 
 
 
 
 
 
 
 
Real estate
$
118

 
$
9

 
$
—

 
$
4

 
$
—

 
$
131

Private equity
19

 
(9
)
 
11

 
(6
)
 
—

 
15


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, 2014:
 
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
$
89

 
$
—

 
$
—

 
$
89

Equity securities:
 
 
 
 
 
 
 
U.S. large-capitalization
291

 
101

 
—

 
392

U.S. small- and mid-capitalization
70

 
—

 
—

 
70

International
37

 
94

 
—

 
131

Other
—

 
7

 
 
 
7

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
105

 
—

 
105

Municipal bonds
—

 
111

 
—

 
111

U.S. treasury and agency securities
—

 
89

 
—

 
89

Other
—

 
44

 
—

 
44

Total
$
487

 
$
551

 
$
—

 
$
1,038

Plus: Medical benefit assets at December 31(a)
 
 
 
 
 
 
125

Less: Net payables at December 31(b)
 
 
 
 
 
 
(54
)
Fair value of postretirement benefit plans assets at year end
 
 
 
 
 
 
$
1,109

(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 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, 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

Other
—

 
2

 
—

 
2

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
97

 
—

 
97

Municipal bonds
—

 
103

 
—

 
103

U.S. treasury and agency securities
—

 
72

 
—

 
72

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.
Net Periodic Benefit Cost
The following table presents the components of the net periodic benefit cost of our pension and postretirement benefit plans during 2014, 2013, and 2012:
 
Pension Benefits
Ameren(a)
 
Postretirement Benefits
Ameren(a)
2014
 
 
 
Service cost
$
79

 
$
19

Interest cost
183

 
50

Expected return on plan assets
(229
)
 
(65
)
Amortization of:
 
 
 
Prior service credit
(1
)
 
(5
)
Actuarial (gain) loss
49

 
(7
)
Net periodic benefit cost (benefit)
$
81

 
$
(8
)
2013
 
 
 
Service cost
$
91

 
$
22

Interest cost
163

 
46

Expected return on plan assets
(218
)
 
(62
)
Amortization of:
 
 
 
Prior service credit
(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 credit
(3
)
 
(6
)
Actuarial loss
75

 
5

Net periodic benefit cost(c)
$
111

 
$
14

(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, 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 2015 are as follows:
  
Pension Benefits
Ameren(a)
 
Postretirement Benefits
Ameren(a)
Regulatory assets:
 
 
 
Prior service credit
$
(1
)
 
$
(4
)
Net actuarial loss
86

 
15

Accumulated OCI:
 
 
 
Net actuarial (gain) loss
2

 
(2
)
Total
$
87

 
$
9

(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, 2014, 2013, and 2012:
  
Pension Costs
 
Postretirement Costs
  
2014
 
2013
 
2012
 
2014
 
2013
 
2012
Ameren Missouri
$
50

 
$
69

 
$
63

 
$
3

 
$
8

 
$
10

Ameren Illinois
30

 
41

 
37

 
(9
)
 
—

 
4

Other
1

 
5

 
2

 
(2
)
 
—

 
—

Ameren(a)
81

 
115

 
102

 
(8
)
 
8

 
14

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
The expected pension and postretirement benefit payments from qualified trust and company funds, which reflect expected future service, as of December 31, 2014, are as follows:
  
Pension Benefits
 
Postretirement Benefits
  
Paid from
Qualified
Trust
 
        Paid from
         Company
      Funds
 
        Paid from
         Qualified
      Trust
 
        Paid from
         Company
      Funds
2015
$
253

 
$
3

 
$
58

 
$
2

2016
256

 
3

 
61

 
2

2017
257

 
4

 
64

 
2

2018
260

 
3

 
68

 
2

2019
260

 
3

 
70

 
2

2020 - 2024
1,273

 
11

 
388

 
11


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, 2014, 2013, and 2012:
  
Pension Benefits
 
Postretirement Benefits
  
2014
 
2013
 
2012
 
2014
 
2013
 
2012
Discount rate at measurement date
4.75
%
 
4.00
%
 
4.50
%
 
4.75
%
 
4.00
%
 
4.50
%
Expected return on plan assets
7.25

 
7.50

 
7.75

 
7.00

 
7.25

 
7.50

Increase in future compensation
3.50

 
3.50

 
3.50

 
3.50

 
3.50

 
3.50

Medical cost trend rate (initial)
(a)

 
(a)

 
(a)

 
5.00

 
5.00

 
5.50

Medical cost trend rate (ultimate)
(a)

 
(a)

 
(a)

 
5.00

 
5.00

 
5.00

Years to ultimate rate
(a)

 
(a)

 
(a)

 
—

 
—

 
1 year


(a)
Not applicable
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
$
(1
)
 
$
138

 
$
1

 
$
39

0.25% increase in salary scale
2

 
13

 
—

 
—

1.00% increase in annual medical trend
—

 
—

 
3

 
36

1.00% decrease in annual medical trend
—

 
—

 
(2
)
 
(33
)

Other
Ameren sponsors a 401(k) plan for eligible employees. The Ameren 401(k) plan covered all eligible employees at December 31, 2014. 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, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Ameren Missouri
$
16

 
$
16

 
$
16

Ameren Illinois
11

 
10

 
9

Other
1

 
1

 
1

Ameren(a)
28

 
27

 
26

(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 and directors, the 2006 Incentive Plan, was replaced prospectively for new grants by the 2014 Incentive Plan effective in April 2014. The 2014 Incentive Plan provides for a maximum of 8 million common shares to be available for grant to eligible employees and directors. It retains many of the features of the 2006 Incentive Plan. To the extent that the issuance of a share that is subject to an outstanding award under the 2006 Incentive Plan would cause Ameren to exceed the maximum authorized shares under the 2006 Incentive Plan, the issuance of that share will take place under the 2014 Incentive Plan. This will reduce the maximum number of shares that may be granted under the 2014 Incentive Plan. The 2014 Incentive 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, 2014, and changes during the year ended December 31, 2014, under the 2006 Incentive Plan and the 2014 Incentive Plan are presented below:
  
Performance Share Units
  
Share
Units
 
Weighted-average
Fair Value per Share Unit
Nonvested at January 1, 2014
1,218,544

 
$
33.23

Granted(a)
688,323

 
38.90

April Grants(b)
38,559

 
50.34

Unearned or forfeited(c)
(97,432
)
 
34.42

Earned and vested(d)
(685,617
)
 
36.12

Nonvested at December 31, 2014
1,162,377

 
$
35.35

(a)
Includes performance share units (share units) granted to certain executive and nonexecutive officers and other eligible employees in 2014 under the 2006 Incentive Plan and the 2014 Incentive Plan.
(b)
In April 2014, certain executive officers were granted additional share units under the 2006 Incentive Plan and the 2014 Incentive Plan. The significant assumptions used to calculate fair value included a prorated three-year risk-free rate ranging from 0.76% to 0.79%, volatility of 12% to 18% for the peer group, and Ameren’s attainment of a three-year average earnings per share threshold during the performance period.
(c)
Includes share units granted in 2012 that were not earned based on performance provisions of the award grants.
(d)
Includes share units granted in 2012 that vested as of December 31, 2014, 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. Actual shares issued for retirement-eligible employees will vary depending on actual performance over the three-year measurement period.
Ameren recorded compensation expense of $19 million, $20 million, and $22 million for the years ended December 31, 2014, 2013, and 2012, respectively, and a related tax benefit of $7 million, $8 million, and $8 million for the years ended December 31, 2014, 2013, and 2012, respectively. Ameren settled performance share units and restricted shares of $33 million, $11 million, and $11 million for the years ended December 31, 2014, 2013, and 2012. There were no significant compensation costs capitalized related to the performance share units during the years ended December 31, 2014, 2013, and 2012. As of December 31, 2014, total compensation cost of $18 million related to nonvested awards not yet recognized has expected to be recognized over a weighted-average period of 20 months.
Performance Share Units
Performance share units have been granted under the 2006 Incentive Plan and the 2014 Incentive 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 if 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 2014, excluding the grants issued in April for certain executive officers, under the 2006 Incentive Plan and the 2014 Incentive Plan was determined to be $38.90. That amount was based on Ameren's closing common share price of $36.16 at December 31, 2013, 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, 2014. 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 0.78%, volatility of 12% to 18% 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 2013 under the 2006 Incentive 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.
Income Taxes
INCOME TAXES
INCOME TAXES
The following table presents the principal reasons for the difference between the effective income tax rate and the statutory federal income tax rate for the years ended December 31, 2014, 2013, and 2012:
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2014
 
 
 
 
 
Statutory federal income tax rate:
35
 %
 
35
 %
 
35
 %
Increases (decreases) from:
 
 
 
 
 
Amortization of investment tax credit
(1
)
 
—

 
(1
)
State tax
3

 
6

 
4

Other permanent items
—

 
—

 
1

Effective income tax rate
37
 %
 
41
 %
 
39
 %
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
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
—

 
—

 
(1
)
Effective income tax rate
37
 %
 
40
 %
 
37
 %


The following table presents the components of income tax expense (benefit) for the years ended December 31, 2014, 2013, and 2012:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
2014
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
(13
)
 
$
(51
)
 
$
27

 
$
(37
)
State
(3
)
 
(2
)
 
(32
)
 
(37
)
Deferred taxes:
 
 
 
 
 
 
 
Federal
222

 
159

 
(12
)
 
369

State
28

 
38

 
22

 
88

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

 
(6
)
Total income tax expense
$
229

 
$
143

 
$
5

 
$
377

2013
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
136

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

 
21

 
(43
)
(a) 
19

Deferred taxes:
 
 
 
 
 
 
 
Federal
64

 
99

 
205

(a) 
368

State
6

 
6

 
36

(a) 
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


(a)
These amounts are substantially related to the reversal of unrecognized tax benefits as a result of 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. The amounts also reflect the increase in deferred tax expense due to available net operating losses.
The Illinois corporate income tax rate was increased to 9.5% from January 2011 through December 2014. The tax rate decreased to 7.75% on January 1, 2015 and is scheduled to decrease to 7.3% on January 1, 2025.
The following table presents the deferred tax assets and deferred tax liabilities recorded as a result of temporary differences at December 31, 2014 and 2013:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
2014
 
 
 
 
 
 
 
Accumulated deferred income taxes, net liability (asset):
 
 
 
 
 
 
 
Plant related
$
2,776

 
$
1,393

 
$
16

 
$
4,185

Regulatory assets, net
82

 
(5
)
 
1

 
78

Deferred employee benefit costs
(80
)
 
(45
)
 
(95
)
 
(220
)
Revenue requirement reconciliation adjustments

—

 
66

 
3

 
69

Tax carryforwards
(107
)
 
(139
)
 
(429
)
 
(675
)
Other
86

 
(22
)
 
70

 
134

Total net accumulated deferred income tax liabilities (assets)(a)
$
2,757

 
$
1,248

 
$
(434
)
 
$
3,571

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
)
Revenue requirement reconciliation adjustments
—

 
(4
)
 
2

 
(2
)
Tax carryforwards
(76
)
 
(95
)
 
(370
)
 
(541
)
Other
67

 
10

 
38

 
115

Total net accumulated deferred income tax liabilities (assets)(b)
$
2,504

 
$
1,071

 
$
(431
)
 
$
3,144


(a)
Includes $49 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2014.
(b)
Includes $20 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2013.
The following table presents the components of deferred tax assets relating to net operating loss carryforwards, tax credit carryforwards, and charitable contribution carryforwards at December 31, 2014:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
Net operating loss carryforwards:
 
 
 
 
 
 
 
Federal(a)
$
75

 
$
127

 
$
255

 
$
457

State(b)
11

 
10

 
53

 
74

Total net operating loss carryforwards
$
86

 
$
137

 
$
308

 
$
531

Tax credit carryforwards:
 
 
 
 
 
 
 
Federal(c)
$
21

 
$
1

 
$
77

 
$
99

State(d)
1

 
2

 
33

 
36

State valuation allowance(e)
(1
)
 
(1
)
 
(2
)
 
(4
)
Total tax credit carryforwards
$
21

 
$
2

 
$
108

 
$
131

Charitable contribution carryforwards(f)
$
—

 
$
—

 
$
19

 
$
19

Valuation allowance(g)
—

 
—

 
(6
)
 
(6
)
Total charitable contribution carryforwards
$
—

 
$
—

 
$
13

 
$
13


(a)
Will begin to expire in 2028.
(b)
Will begin to expire in 2020.
(c)
Will begin to expire in 2029.
(d)
Began to expire in 2013.
(e)
This balance increased by less than $1 million, $- million, and $- million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, during 2014.
(f)
These began to expire in 2013.
(g)
This balance increased by $3 million, $- million and $- million for Ameren, Ameren Missouri and Ameren Illinois, respectively, during 2014.
The following table presents the components of deferred tax assets relating to net operating loss carryforwards, tax credit carryforwards, and charitable contribution carryforwards at December 31, 2013:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
Net operating loss carryforwards:
 
 
 
 
 
 
 
Federal(a)
$
61

 
$
84

 
$
215

 
$
360

State(b)
3

 
11

 
34

 
48

Total net operating loss carryforwards
$
64

 
$
95

 
$
249

 
$
408

Tax credit carryforwards:
 
 
 
 
 
 
 
Federal(c)
$
12

 
$
—

 
$
76

 
$
88

State(d)
1

 
1

 
32

 
34

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

 
$
—

 
$
106

 
$
118

Charitable contribution carryforwards(f)
$
—

 
$
—

 
$
18

 
$
18

Valuation allowance(g)
—

 
—

 
(3
)
 
(3
)
Total charitable contribution carryforwards
$
—

 
$
—

 
$
15

 
$
15


(a)
Will begin to expire in 2028
(b)
Will begin to expire in 2019.
(c)
Will begin to expire in 2029.
(d)
Began to expire in 2013.
(e)
Balance increased by $2 million, $- million, and $- million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, during 2013.
(f)
These began to expire in 2013.
(g)
This balance increased by $3 million, $- million, and $- million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, during 2013.
Uncertain Tax Positions
A reconciliation of the change in the unrecognized tax benefit balance during the years ended December 31, 2012, 2013, and 2014, is as follows:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
Unrecognized tax benefits – January 1, 2012
$
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 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 (decreases) based on tax positions related to 2013
16

 
—

 
53

(a) 
69

Changes related to settlements with taxing authorities
—

 
—

 
—

 
—

Decreases related to the lapse of statute of limitations
1

 
—

 
—

 
1

Unrecognized tax benefits – December 31, 2013
$
31

 
$
(1
)
 
$
60

 
$
90

Increases based on tax positions prior to 2014
1

 
1

 
4

 
6

Decreases based on tax positions prior to 2014
(32
)
 
(1
)
 
(9
)
 
(42
)
Increases based on tax positions related to 2014
—

 
—

 
—

 
—

Changes related to settlements with taxing authorities
—

 
—

 
—

 
—

Increases related to the lapse of statute of limitations
—

 
—

 
—

 
—

Unrecognized tax benefits (detriments) – December 31, 2014
$
—

 
$
(1
)
 
$
55

 
$
54

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

 
$
(1
)
 
$
(1
)
 
$
1

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

 
$
—

 
$
51

(a) 
$
54

Total unrecognized tax benefits that, if recognized, would affect the effective tax rates as of December 31, 2014
$
—

 
$
(1
)
 
$
53

(a) 
$
52


(a)
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, 2012, 2013, and 2014, is as follows:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
Liability for interest – January 1, 2012
$
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

Interest charges (income) for 2014
—

 
—

 
(1
)
 
(1
)
Liability for interest – December 31, 2014
$
—

 
$
—

 
$
—

 
$
—


As of December 31, 2012, 2013, and 2014, the Ameren Companies have accrued no amount for penalties with respect to unrecognized tax benefits.

In 2014, final settlements for tax years 2007 through 2011 were reached with the IRS. These settlements, which resolved the uncertain tax positions associated with the timing of research tax deductions for these years, resulted in a decrease in Ameren’s and Ameren Missouri’s unrecognized tax benefits of $20 million, and $13 million, respectively. In addition, the settlement for tax years 2007 through 2011 provided certainty for the previously uncertain tax positions associated with the timing of research tax deductions for the remaining open tax years of 2012, 2013, and 2014. As a result, the certainty provided from the settlement resulted in an $18 million decrease in both Ameren’s and Ameren Missouri’s unrecognized tax benefits. The settlement also resulted in a $2 million increase to Ameren’s state unrecognized tax benefits. The net reduction in unrecognized tax benefits in 2014 did not materially affect income tax expense for the Ameren Companies.
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 affect income tax expense for the Ameren Companies. However, the liability for interest related to these unrecognized tax benefits was released in 2013. In 2013, Ameren adopted an accounting method change as a result of guidance issued by the IRS, with respect to the amount and timing of the deductions to maintain, replace, or improve generation property.
It is reasonably possible that a settlement will be reached with the IRS in the next 12 months for the years 2012 and 2013. However, the Ameren Companies do not believe any settlements would have a material effect on its net income from continuing operations.
State income tax returns are generally subject to examination for a period of three years after filing. 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 currently do not 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 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 must acquire capacity sufficient to meet its obligations to customers. Ameren Illinois uses periodic RFP processes that are administered by the IPA to contract capacity on behalf of its customers. Ameren Missouri participates in the RFP process and has been a winning supplier for certain periods. In 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 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 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 settled physically from June 1, 2011, through May 31, 2014. Ameren Missouri was among the winning suppliers in the energy product RFP process. In 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 ended May 31, 2012, approximately 40,800 megawatthours at approximately $29 per megawatthour during the 12 months ended May 31, 2013, and approximately 40,800 megawatthours at approximately $28 per megawatthour during the 12 months ended May 31, 2014. The energy product agreements between Ameren Missouri and Ameren Illinois for the periods ended May 31, 2012, and May 31, 2013, were for off-peak hours only.
In 2014, Ameren Illinois used an RFP process, administered by the IPA, to procure energy products that will settle physically from December 1, 2014, through May 31, 2017. Ameren Missouri was among the winning suppliers in the energy product RFP process. As a result, Ameren Missouri and Ameren Illinois entered into energy product agreements by which Ameren Missouri agreed to sell and Ameren Illinois agreed to purchase approximately 168,400 megawatthours at approximately $51 per megawatthour during the period of January 1, 2015, through February 28, 2017.
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.
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. A shared services support agreement can be terminated at any time by the mutual agreement of Ameren Services and that affiliate or by either party 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 takes 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 can 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, 2014 and 2013, there were no collateral postings required of Ameren Missouri related to the Illinois power procurement agreements.
Tax Allocation Agreement
See Note 1 – Summary of Significant Accounting Policies for a discussion of the tax allocation agreement. At December 31, 2014, Ameren Missouri and Ameren Illinois had an intercompany receivable balance with Ameren (parent) of $58 million and $15 million, respectively, related to the tax allocation agreement.
The following table presents the impact on Ameren Missouri and Ameren Illinois of related party transactions for the years ended December 31, 2014, 2013, and 2012. 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
 
2014
$
5

$
(a)

with Ameren Illinois
 
 
2013
 
3

 
(a)

 
 
 
2012
 
(b)

 
(a)

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2014
 
21

 
2

rent and facility services
 
 
2013
 
21

 
1

 
 
 
2012
 
19

 
1

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2014
 
1

 
(b)

miscellaneous support services
 
 
2013
 
1

 
3

 
 
 
2012
 
1

 
(b)

Total Operating Revenues
 
 
2014
$
27

$
2

 
 
 
2013
 
25

 
4

 
 
 
2012
 
20

 
1

Ameren Illinois power supply
Purchased Power
 
2014
$
(a)

$
5

agreements with Ameren Missouri
 
 
2013
 
(a)

 
3

 
 
 
2012
 
(a)

 
(b)

Ameren Illinois transmission
Purchased Power
 
2014
 
(a)

 
2

services with ATXI
 
 
2013
 
(a)

 
2

 
 
 
2012
 
(a)

 
3

Total Purchased Power
 
 
2014
$
(a)

$
7

 
 
 
2013
 
(a)

 
5

 
 
 
2012
 
(a)

 
3

Ameren Services support services
Other Operations and
 
2014
$
124

$
109

agreement
Maintenance
 
2013
 
116

 
93

 
 
 
2012
 
106

 
88

Insurance premiums(c)
Other Operations and
 
2014
 
(b)

 
(a)

 
Maintenance
 
2013
 
(b)

 
(a)

 
 
 
2012
 
(b)

 
(a)

Total Other Operations and
 
 
2014
$
124

$
109

Maintenance Expenses
 
 
2013
 
116

 
93

 
 
 
2012
 
106

 
88

Money pool borrowings (advances)
Interest (Charges)
 
2014
$
(b)

$
(b)

 
Income
 
2013
 
(b)

 
(b)

 
 
 
2012
 
(b)

 
(b)

(a)
Not applicable.
(b)
Amount less than $1 million.
(c)
Represents insurance premiums paid to Missouri Energy Risk Assurance Company LLC, an affiliate, for replacement power.
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, 2014. 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 LLC
$
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)
NEIL provides $2.25 billion in property damage, decontamination, and premature decommissioning insurance.
(e)
All NEIL-insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL.
(f)
European Mutual Association for Nuclear Insurance provides $500 million in excess of the $2.25 billion property coverage provided by NEIL.
(g)
Provides replacement power cost insurance in the event of a prolonged accidental outage. Weekly indemnity is 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. Nonradiation events are sub-limited to $328 million.
(h)
Provides replacement power cost insurance in the event of a prolonged accidental outage. The coverage commences after the first 52 weeks of insurance coverage from NEIL concludes; it is a weekly indemnity of up to $0.9 million for 71 weeks in excess of the $3.6 million per week set forth above. Missouri Energy Risk Assurance Company LLC is an affiliate; it 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 most recent five-year inflationary adjustment became effective in September 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 on nuclear facilities are covered under NEIL’s policies, subject to an industrywide aggregate policy coverage limit of $3.24 billion within a 12-month period, or $1.83 billion for events not involving radiation contamination.
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, 2014:
 
2015
 
2016
 
2017
 
2018
 
2019
 
After 5 Years
 
Total
Ameren:(a)
 
 
 
 
 
 
 
 
 
 
 
 
 
Minimum capital lease payments(b)
$
33

 
$
33

 
$
33

 
$
32

 
$
32

 
$
360

 
$
523

Less amount representing interest
27

 
27

 
27

 
26

 
25

 
97

 
229

Present value of minimum capital lease payments
$
6

 
$
6

 
$
6

 
$
6

 
$
7

 
$
263

 
$
294

Operating leases(c)
13

 
12

 
12

 
12

 
11

 
38

 
98

Total lease obligations
$
19

 
$
18

 
$
18

 
$
18

 
$
18

 
$
301

 
$
392

Ameren Missouri:
 
 
 
 
 
 
 
 
 
 
 
 
 
Minimum capital lease payments(b)
$
33

 
$
33

 
$
33

 
$
32

 
$
32

 
$
360

 
$
523

Less amount representing interest
27

 
27

 
27

 
26

 
25

 
97

 
229

Present value of minimum capital lease payments
$
6

 
$
6

 
$
6

 
$
6

 
$
7

 
$
263

 
$
294

Operating leases(c)
11

 
11

 
11

 
10

 
10

 
37

 
90

Total lease obligations
$
17

 
$
17

 
$
17

 
$
16

 
$
17

 
$
300

 
$
384

Ameren Illinois:
 
 
 
 
 
 
 
 
 
 
 
 
 
Operating leases(c)
$
1

 
$
1

 
$
1

 
$
1

 
$
1

 
$
1

 
$
6

(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 obligations of $2 million, $1 million, and $1 million for Ameren, Ameren Missouri, and Ameren Illinois for these items are included in the 2015 through 2019 columns, respectively.
The following table presents total rental expense, included in operating expenses, for the years ended December 31, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Ameren(a)
$
37

 
$
32

 
$
33

Ameren Missouri
32

 
29

 
29

Ameren Illinois
25

 
21

 
19

(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 fuel, purchased power, and other commitments for fuel at December 31, 2014. Ameren’s and Ameren Missouri’s purchased power commitments include a 102-megawatt power purchase agreement with a wind farm operator, which expires in 2024. Ameren’s and Ameren Illinois’ purchased power commitments 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, 2014. In addition, the Other column includes Ameren's and Ameren Missouri's obligations related to customer energy efficiency programs under the MEEIA as approved by the MoPSC's December 2012 electric rate order. Ameren Missouri expects to incur costs of $71 million in 2015 for these customer energy efficiency programs. See Note 2 – Rate and Regulatory Matters for additional information about the MEEIA.
 
Coal
 
Natural
Gas(a)
 
Nuclear
Fuel
 
Purchased
Power(b)
 
Methane
Gas
 
Other
 
Total
Ameren:(c)
 
 
 
 
 
 
 
 
 
 
 
 
 
2015
$
654

 
$
222

 
$
53

 
$
190

 
$
3

 
$
195

 
$
1,317

2016
659

 
125

 
60

 
104

 
3

 
78

 
1,029

2017
682

 
85

 
59

 
66

 
4

 
53

 
949

2018
111

 
53

 
82

 
55

 
5

 
51

 
357

2019
114

 
32

 
42

 
56

 
5

 
54

 
303

Thereafter
—

 
71

 
138

 
596

 
76

 
350

 
1,231

Total
$
2,220

 
$
588

 
$
434

 
$
1,067

 
$
96

 
$
781

 
$
5,186

Ameren Missouri:
 
 
 
 
 
 
 
 
 
 
 
 
 
2015
$
654

 
$
39

 
$
53

 
$
21

 
$
3

 
$
128

 
$
898

2016
659

 
22

 
60

 
21

 
3

 
39

 
804

2017
682

 
17

 
59

 
21

 
4

 
26

 
809

2018
111

 
11

 
82

 
21

 
5

 
27

 
257

2019
114

 
10

 
42

 
21

 
5

 
27

 
219

Thereafter
—

 
22

 
138

 
106

 
76

 
183

 
525

Total
$
2,220

 
$
121

 
$
434

 
$
211

 
$
96

 
$
430

 
$
3,512

Ameren Illinois:
 
 
 
 
 
 
 
 
 
 
 
 
 
2015
$
—

 
$
183

 
$
—

 
$
169

 
$
—

 
$
29

 
$
381

2016
—

 
103

 
—

 
83

 
—

 
24

 
210

2017
—

 
68

 
—

 
45

 
—

 
24

 
137

2018
—

 
42

 
—

 
34

 
—

 
24

 
100

2019
—

 
22

 
—

 
35

 
—

 
27

 
84

Thereafter
—

 
49

 
—

 
490

 
—

 
167

 
706

Total
$
—

 
$
467

 
$
—

 
$
856

 
$
—

 
$
295

 
$
1,618

(a)
Includes amounts for generation and for distribution.
(b)
The purchased power amounts for Ameren and Ameren Illinois include agreements through 2032 for renewable energy credits 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.
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 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 and implementing environmental regulations that will have a significant impact on the electric utility industry. Over time, compliance with these regulations could be costly for certain companies, including Ameren Missouri, that operate coal-fired power plants. Significant new rules proposed or promulgated include the regulation of CO2 emissions from existing power plants through the proposed Clean Power Plan and from new power plants through the revised NSPS; revised national ambient air quality standards for ozone, fine particulates, SO2, and NOx emissions; the CSAPR, which requires further reductions of SO2 emissions and NOx emissions from power plants; a regulation governing management of CCR and CCR impoundments; the MATS, which require reduction of emissions of mercury, toxic metals, and acid gases from power plants; revised NSPS for particulate matter, SO2, and NOx emissions from new sources; new effluent standards applicable to waste water discharges from power plants 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 Ameren Missouri’s energy centers. Certain of these new and proposed regulations, if adopted, are likely to be challenged through litigation, so their ultimate implementation, as well as the timing of any such implementation, is uncertain. Although many details of the future regulations are unknown, the combined effects of the new and proposed environmental regulations could result in significant capital expenditures and increased operating costs for Ameren and Ameren Missouri. Compliance with these environmental laws and regulations could be prohibitively expensive, result in the closure or alteration of the operation of some of Ameren Missouri’s energy centers, or require capital investment. Ameren and Ameren Missouri expect these costs would be recoverable through rates, subject to MoPSC prudence review, but the nature and timing of costs, as well as the applicable regulatory framework, could result in regulatory lag.
As of December 31, 2014, Ameren and Ameren Missouri estimate capital expenditure investments of $350 million to $400 million through 2019 to comply with existing environmental regulations. Considerable uncertainty remains in this estimate. The actual amount of capital investments required 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. This estimate does not include the impacts of the proposed Clean Power Plan’s reduction in emissions of CO2, which is discussed below.
Ameren Missouri's current plan for compliance with existing environmental regulations 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. Ameren Missouri's compliance plan assumes the installation of additional controls including mercury control technology at multiple energy centers within its coal-fired fleet through 2019. However, Ameren Missouri continues to evaluate its operations and options to determine how to comply with the CSAPR, the MATS, and other recently finalized or proposed EPA regulations. Ameren Missouri may be required to install additional pollution controls within the next six to 10 years. As the Clean Power Plan is still subject to revision by the EPA and implementation by the states, Ameren Missouri has not finalized a compliance plan for the proposed rule.
The following sections describe the more significant new or proposed environmental laws and rules and environmental enforcement and remediation matters that affect or could affect our operations.
Clean Air Act
Both federal and state laws require significant reductions in SO2 and NOx through either emission source reductions or the use and retirement of emission allowances. In 2005, the EPA issued regulations with respect to SO2 and NOx emissions (the CAIR). The CSAPR replaced the CAIR and became effective on January 1, 2015 for SO2 and annual NOx reductions, and on May 1, 2015, will become effective for ozone season NOx reductions. There will be further reductions in 2017 and in subsequent years. Ameren Missouri expects to have sufficiently reduced emissions and have sufficient allowances for 2015 to avoid making external purchases to comply with CSAPR. Ameren Missouri has already taken actions to prepare for the implementation of the CSAPR, including the installation of two scrubbers at its Sioux energy center and burning ultra-low sulfur coal. Ameren Missouri does not expect to make additional capital investments to comply with the CSAPR. However, Ameren Missouri will incur additional operations and maintenance costs to lower its emissions at one or more of its energy centers in compliance with the CSAPR. These higher operations and maintenance costs are expected to be collected from customers through the FAC or higher base rates.
In December 2011, the EPA issued the MATS under the Clean Air Act, which requires emission reductions for mercury and other hazardous air pollutants, such as acid gases, trace 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, compliance can be achieved by averaging emissions from similar 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 were granted extensions and expect to comply with the MATS by April 2016. Ameren Missouri expects to make additional capital investments to comply with the MATS. These capital expenditure investments are included in Ameren's and Ameren Missouri's estimate above. In addition, Ameren Missouri will incur additional operations and maintenance costs to lower its emissions at one or more of its energy centers in compliance with the MATS. These higher operations and maintenance costs are expected to be collected from customers through the FAC or higher base rates.
In December 2014, the EPA published its proposal to strengthen the 2008 national ambient air quality standard for ozone. A final standard is expected in October 2015, after which states that do not meet the standard must develop and implement plans to achieve compliance with the air quality standard. Ameren Missouri is currently evaluating the proposed standard and the possible effects on its operations.
Greenhouse Gas Regulation
Beginning in 2011, greenhouse gas emissions from stationary sources, such as power plants, became subject to regulation under the Clean Air Act. As a result of this action, Ameren Missouri is 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 for regulating greenhouse gas emissions from stationary sources, such as power plants, through operating permits and the NSR programs. The rule requires any source that already has an operating permit to have provisions relating to greenhouse gas emissions added to its permit upon renewal. Currently, all Ameren Missouri energy centers have operating permits that have been modified to address greenhouse gas emissions. In June 2014, the United States Supreme Court ruled that the EPA may regulate greenhouse gas emissions through operating permits and NSR programs at stationary sources that are already subject to those programs, but may not apply operating permits and NSR programs to non-stationary sources solely as a result of their greenhouse gas emissions. Ameren Missouri does not expect the decision to have a significant effect on its operations.
In January 2014, the EPA published proposed regulations that would set revised CO2 emissions standards for new power plants. The proposed standards would establish separate emissions limits for new natural-gas-fired plants and new coal-fired plants. In June 2014, the EPA proposed the Clean Power Plan, which sets forth CO2 emissions standards that would be applicable to existing power plants. The proposed Clean Power Plan would require each state to develop plans to achieve CO2 emission standards that the EPA calculated for each state. The EPA believes that the Clean Power Plan would achieve a 30% reduction in the nation's existing power plant CO2 emissions from 2005 levels by 2030. The proposed rule also has interim goals of aggressively reducing CO2 emissions by 2020. The EPA expects the proposed rule will be finalized in 2015. If the proposed rule is finalized, states would have one to three years to develop compliance plans. States would be allowed to develop independent plans or to join with other states to develop joint plans. Ameren Missouri is evaluating the proposed Clean Power Plan and the potential impact to its operations, including those related to electric system reliability. Significant uncertainty exists regarding the standard for existing power plants, as the finalized rule could be different from the proposed rule and will be subject to legal challenges, either of which could result in the amount and timing of CO2 emission standards being revised.
Preliminary studies suggest that if the proposed Clean Power Plan were to be finalized in its current form, Ameren Missouri may need to incur new or accelerated capital expenditures and increased fuel costs in order to achieve compliance. As proposed, the Clean Power Plan would require the states, including Missouri and Illinois, to submit compliance plans as early as 2016. The states’ compliance plans might require Ameren Missouri to construct natural gas-fired combined cycle generation and renewable generation, at a currently estimated cost of approximately $2 billion by 2020, that Ameren Missouri believes would otherwise not be necessary to meet the energy needs of its customers. Additionally, Missouri’s implementation of the proposed rules, if adopted, could result in the closure or alteration of the operation of some of Ameren Missouri’s coal and natural gas-fired energy centers, which could result in increased operating costs or impairment of assets. Ameren Missouri expects substantially all of these increased costs, which could begin in 2017, to be recoverable, subject to MoPSC prudence review, through substantially higher electric rates charged to its customers.
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 could lead to increased liquidity needs and higher financing costs. These compliance costs could be prohibitive at some of Ameren Missouri’s energy centers, which could result in the impairment of long-lived assets if costs are not recovered through rates. Mandatory limits on the emission of greenhouse gases could increase costs for its customers or have a material adverse effect on Ameren's and Ameren Missouri's results of operations, financial position, and liquidity if regulators delay or deny recovery in rates of these compliance costs. Ameren's and Ameren Missouri's earnings might benefit from increased investment to comply with greenhouse gas limitations to the extent that the investments are reflected and recovered timely in rates charged to customers.
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 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. Ameren Missouri believes its defenses are meritorious and is defending itself vigorously. However, there can be no assurances that it will be successful in its efforts.
The ultimate resolution of this matter could have a material adverse effect 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 August 2014, the EPA published the final rule applicable to cooling water intake structures at existing power plants. The rule requires a case-by-case evaluation and plan for reducing the mortality of aquatic organisms impinged on the facility’s intake screens or entrained through the plant's cooling water system. Implementation of this rule will be administered through each power plant’s water discharge permitting process. All coal-fired and nuclear energy centers at Ameren Missouri are subject to this rule. The rule could have an adverse effect on Ameren’s and Ameren Missouri’s 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 and if those investments are not recovered timely in electric rates charged to our customers.
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. The EPA is expected to issue final guidelines in September 2015.
Ash Management
In December 2014, the EPA issued regulations regarding the management and disposal of CCR, which will affect future disposal and handling costs at Ameren Missouri's energy centers. The EPA regulations will be effective 180 days after publication in the Federal Register, which is anticipated in early 2015. The rule allows for the management of CCR as a solid waste, as well as for its continued beneficial uses, such as recycling, which could reduce the amount to be disposed. The rule established criteria regarding the structural integrity, location, and operation of CCR impoundments and landfills. It requires groundwater monitoring and closure of impoundments if the groundwater standards under the rule are not achieved. Ameren Missouri is currently evaluating the rule to determine its impact on current management of CCR and the potential costs associated with compliance. Ameren Missouri is also evaluating the potential effect the new rule will have on its AROs associated with ash ponds. Ameren Missouri's capital expenditure plan includes the cost of constructing landfills as part of its environmental compliance plan. Ameren Missouri expects certain of its ash ponds could be closed within the next five years.
The EPA's regulations issued in December 2014 regarding the management and disposal of CCR do not apply to inactive ash ponds at plants no longer in operation, such as the Meredosia and Hutsonville energy centers.
Remediation
We are involved in a number of remediation actions to clean up sites affected by hazardous substances, as required by federal and state law. Such laws 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 federal or state governments as a potentially responsible party at several contaminated sites.
As of December 31, 2014, 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. Ameren Illinois estimates it could substantially conclude remediation efforts at most of these sites by 2018. The ICC allows 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, 2014, Ameren Illinois estimated the obligation related to these former MGP sites at $250 million to $314 million. Ameren and Ameren Illinois recorded a liability of $250 million to represent their estimated minimum obligation for these sites, as no other amount within the range was 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 formerly used an off-site landfill, which Ameren Illinois did not own, in connection with the operation of a previously-owned energy center. Ameren Illinois could be required to perform certain maintenance activities at that landfill. As of December 31, 2014, 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, 2014, Ameren Illinois recorded a liability of $0.7 million to represent its best estimate of the obligation for these sites.
In 2008, the EPA issued an administrative order to Ameren Missouri pertaining to a former coal tar distillery operated by Koppers Company or its predecessor and successor companies. While Ameren Missouri is the current owner of the site, which is located in St. Louis, Missouri, it did not conduct any of the manufacturing operations involving coal tar or its byproducts. Ameren Missouri, along with two other potentially responsible parties, are performing a site investigation. As of December 31, 2014, 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 also participated in the investigation of various sites located in Sauget, Illinois. In 2000, the EPA notified Ameren Missouri and numerous other companies, including Solutia, Inc., that former landfills and lagoons at those sites 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 at Sauget Area 2 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.
In December 2013, the EPA issued its record of decision for Sauget Area 2 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, 2014, Ameren Missouri estimated its obligation related to Sauget Area 2 at $1 million to $2.5 million. Ameren Missouri recorded a liability of $1 million to represent its estimated minimum obligation, as no other amount within the range was a better estimate.
In 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, 2014, Ameren Missouri estimated the obligation related to this 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. Ameren Missouri had liability insurance coverage for the Taum Sauk incident, subject to certain limits and deductibles.
In 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, Ameren Missouri claims that the insurance company breached its duty to indemnify Ameren Missouri for losses resulting from the incident. In September 2014, the United States District Court for the Eastern District of Missouri ordered the case to be transferred to the United States District Court for the Southern District of New York for trial. The transfer order has been stayed pending resolution of Ameren Missouri’s October 2014 appeal of that order to the United States Court of Appeals for the Eighth Circuit.
In June 2014, Ameren Missouri reached a settlement with another group of insurers who provided Ameren Missouri with liability coverage on the date of the Taum Sauk incident. In accordance with that settlement, Ameren Missouri received a payment of $27 million.
As of December 31, 2014, Ameren Missouri had an insurance receivable of $41 million. It ultimately expects to collect this receivable from the remaining insurance company in the pending litigation described above. This receivable is included in “Other assets” on Ameren’s and Ameren Missouri’s balance sheets as of December 31, 2014. Ameren's and Ameren Missouri's results of operations, financial position, and liquidity could be adversely affected if Ameren Missouri's remaining liability insurance claim is not paid.
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 78 as the average number of parties as of December 31, 2014. Each lawsuit seeks unspecified damages that, if awarded at trial, typically would be shared among the various defendants.
The following table presents the pending asbestos-related lawsuits filed against the Ameren Companies as of December 31, 2014:
Ameren
 
Ameren
Missouri
 
Ameren
Illinois
 
Total(a)
1
 
45
 
57
 
70

(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, 2014, Ameren, Ameren Missouri, and Ameren Illinois had liabilities of $12 million, $5 million, and $7 million, respectively, recorded to represent their best estimates 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 the cash expenditures in excess of the amount included in base electric rates is to be recovered from a trust fund that was established when Ameren acquired IP. At December 31, 2014, the trust fund balance was $22 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 electric customers within IP’s historical service territory.
Ameren Illinois Municipal Taxes
Ameren Illinois previously received tax liability notices from eight municipalities, including the City of O'Fallon, alleging that Ameren Illinois failed to collect prior-period taxes from certain customers in each municipality. In November 2014, Ameren Illinois reached a settlement agreement with the City of O'Fallon and paid $1 million for the prior-period taxes. With respect to the seven other communities, Ameren Illinois believes its defenses to the allegations are meritorious and its potential loss is immaterial.
Divestiture Transactions and Discontinued Operations (Notes)
DIVESTITURE TRANSACTIONS AND DISCONTINUED OPERATIONS
NOTE 16 – DIVESTITURE TRANSACTIONS AND DISCONTINUED OPERATIONS
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 dated December 2, 2013.
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. These energy centers were abandoned and had an immaterial property and plant asset balance as of December 31, 2014. The EPA's regulations issued in December 2014 regarding the management and disposal of CCR, as discussed in Note 15 – Commitments and Contingencies, do not apply to inactive ash ponds at plants no longer in operation, such as the Meredosia and Hutsonville energy centers. 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.
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. The agreement with Rockland Capital requires $17 million of the purchase price to be held in escrow until January 31, 2016, to fund certain indemnity obligations, if any, of Medina Valley. The Rockland Capital escrow receivable balance and the corresponding payable due to Genco is reflected on Ameren's December 31, 2014, consolidated balance sheet in "Other assets" and in "Other deferred credits and liabilities," respectively. Medina Valley expects to pay Genco any remaining portion of the escrow balance on January 31, 2016. Ameren did not record a gain from its sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers.
Discontinued Operations Presentation
In March 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, in December 2013, coinciding with the completion of the divestiture of New AER to IPH, Ameren determined that the Meredosia and Hutsonville energy centers, which were both not operating, had been abandoned and also qualified for discontinued operations presentation. Ameren has begun to demolish the Hutsonville energy center and expects to demolish the Meredosia energy center thereafter. 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, 2014, 2013, and 2012:
 
Year ended
 
 
2014
 
2013
 
2012
 
Operating revenues
$
1

 
$
1,037

 
$
1,047

 
Operating expenses
(2
)

(1,207
)
(a) 
(3,474
)
(b) 
Operating income (loss)
(1
)
 
(170
)
 
(2,427
)
 
Other income (loss)
—

 
(1
)
 
—

 
Interest charges
—

 
(39
)
 
(56
)
 
Income (loss) before income taxes
(1
)
 
(210
)
 
(2,483
)
 
Income tax (expense) benefit
—

 
(13
)
 
987

 
Income (loss) from discontinued operations, net of taxes
$
(1
)
 
$
(223
)
 
$
(1,496
)
 
(a)
Includes a $201 million pretax loss on disposal relating to the New AER divestiture.
(b)
Includes a noncash pretax asset impairment charge of $2.58 billion to reduce the carrying value of AER's energy centers to their estimated fair value under held and used accounting guidance.
Ameren’s results of operations for the year ended December 31, 2014, include adjustments for the New AER net working capital amount owed to IPH and for certain contingent liabilities associated with the New AER divestiture. In 2014, Ameren paid $13 million to IPH for the final working capital adjustment and a portion of the previously-recorded contingent liabilities. Additionally, Ameren recognized the operating revenues and operating expenses associated with the Elgin, Gibson City, and Grand Tower gas-fired energy centers prior to the completion of their sale to Rockland Capital on January 31, 2014. The final tax basis of the AER disposal group and the related tax benefit resulting from the transaction with IPH are dependent upon the resolution of tax matters under audit. It is reasonably possible in the next 12 months these tax audits will be completed. As a result, tax expense and benefits ultimately realized from the divestitures may differ materially from those recorded as of December 31, 2014, including the final resolution of Ameren's uncertain tax positions.
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). Ameren did not receive any cash proceeds from IPH for the divestiture of New AER. 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.
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. Ameren did 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 because 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.
New AER and the Elgin, Gibson City, and Grand Tower energy centers were impaired under held and used accounting guidance in 2012. 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. As a result of this sharp decline in the market price of power and the related impact on electric margins, Ameren evaluated, 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 2012, Ameren determined that the estimated undiscounted cash flows during the period in which it expected to continue to own its Merchant Generation 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.

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, 2014 and 2013:
 
December 31, 2014
 
December 31, 2013
Assets of discontinued operations
 
 
 
Accounts receivable and unbilled revenue
$
—

 
$
5

Materials and supplies
—

 
5

Property and plant, net
—

 
142

Accumulated deferred income taxes, net(a)
15

 
13

Total assets of discontinued operations
$
15

 
$
165

Liabilities of discontinued operations
 
 
 
Accounts payable and other current obligations
$
1

 
$
5

Asset retirement obligations(b)
32

 
40

Total liabilities of discontinued operations
$
33

 
$
45

(a)
The December 31, 2014 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 $32 million and $31 million at December 31, 2014 and 2013, respectively.
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, with interest, on December 2, 2015, or sooner, as cash collateral requirements are reduced. 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 did not have significant continuing involvement with or material cash flows from the Elgin, Gibson City, or Grand Tower energy centers after their sale.
Pursuant to the IPH transaction agreement, as amended, Ameren is obligated to pay up to $29 million for certain contingent liabilities as of December 31, 2014, which were included in "Other current liabilities" on Ameren's December 31, 2014 consolidated balance sheet.
The note receivable from Marketing Company related to the cash collateral support provided to New AER was $12 million and $18 million at December 31, 2014 and 2013, respectively, and was reflected on Ameren's consolidated balance sheet in "Miscellaneous accounts and notes receivable" at December 31, 2014. This receivable is due to Ameren, with interest, on December 2, 2015, or sooner as cash collateral requirements are reduced. In addition, as of December 31, 2014, if Ameren’s credit ratings had been below investment grade, Ameren could have been required to post additional cash collateral in support of New AER in the amount of $26 million, which includes $11 million currently covered by Ameren guarantees. This cash collateral support is part of Ameren’s obligation to provide certain limited credit support to New AER until December 2, 2015, as discussed below.
Ameren Guarantees and Letters of Credit
The IPH transaction agreement, as amended, requires Ameren to maintain its financial obligations with respect to all credit support provided to New AER as of the December 2, 2013 closing date of the divestiture. Ameren must also provide such additional credit support as required by contracts entered into prior to the closing date, in each case until December 2, 2015. 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 pursuant to which Dynegy will, among other things, guarantee IPH's indemnification obligations until December 2, 2015.
In addition to the $29 million of contingent liabilities recorded on Ameren’s December 31, 2014 consolidated balance sheet, Ameren had a total of $114 million in guarantees outstanding for New AER that were not recorded on Ameren’s December 31, 2014 consolidated balance sheet, which included:
•
$106 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, 2014, Ameren would have been required under its guarantees to provide $11 million to the counterparties.
•
$8 million related to requirements for lease agreements and potential environmental obligations. If New AER had not fulfilled its lease obligation as of December 31, 2014, Ameren would have been required to provide approximately $7 million to the leasing counterparty.
Additionally, at December 31, 2014, Ameren had issued letters of credit totaling $9 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 with respect to any of these guarantees or letters of credit was probable as of December 31, 2014.
Segment Information
SEGMENT INFORMATION
SEGMENT INFORMATION
Ameren has two reportable segments: Ameren Missouri and Ameren Illinois. Ameren Missouri and Ameren Illinois each have one reportable segment. The Ameren Missouri segment for both Ameren and Ameren Missouri includes all the operations of Ameren Missouri 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 and capital expenditures from continuing operations for the years ended December 31, 2014, 2013, and 2012, and total assets in continuing operations as of December 31, 2014, 2013, and 2012:
 
Ameren
Missouri
 
Ameren
Illinois
 
Other
 
Intersegment
Eliminations
 
Consolidated
 
2014
 
 
 
 
 
 
 
 
 
 
External revenues
$
3,526

 
$
2,496

 
$
31

 
$
—

 
$
6,053

 
Intersegment revenues
27

 
2

 
2

 
(31
)
 
—

 
Depreciation and amortization
473

 
263

 
9

 
—

 
745

 
Interest and dividend income
28

 
7

 
2

 
—

 
37

 
Interest charges
211

 
112

 
18

 
—

 
341

 
Income taxes
229

 
143

 
5

 
—

 
377

 
Net income (loss) attributable to Ameren Corporation from continuing operations
390

 
201

 
(4
)
 
—

 
587

 
Capital expenditures
747

 
835

 
203

(a) 
—

 
1,785

 
Total assets
13,541

 
8,381

 
942

 
(203
)
 
22,661

(b) 
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) 
.
(a)
Includes the elimination of intercompany transfers.
(b)
Excludes total assets from discontinued operations of $15 million, $165 million, and $1,611 million as of December 31, 2014, 2013, and 2012, respectively.
Selected Quarterly Information
SELECTED QUARTERLY INFORMATION
SELECTED QUARTERLY INFORMATION (Unaudited) (In millions, except per share amounts)
Ameren
2014
 
 
2013
Quarter ended (a)
March 31
 
June 30
 
September 30
 
December 31
 
 
March 31
 
June 30
 
September 30
 
December 31
Operating revenues
$
1,594

 
$
1,419

 
$
1,670

 
$
1,370

 
 
$
1,475

 
$
1,403

 
$
1,638

 
$
1,322

Operating income
246

 
322

 
561

 
125

 
 
185

 
261

 
567

 
171

Net income (loss)
98

 
150

 
295

 
49

 
 
(143
)
 
96

 
304

 
38

Net income attributable to Ameren Corporation – continuing operations
$
97

 
$
150

 
$
294

 
$
46

 
 
$
54

 
$
105

 
$
305

 
$
48

Net income (loss) attributable to Ameren Corporation – discontinued operations
(1
)
 
(1
)
 
(1
)
 
2

 
 
(199
)
 
(10
)
 
(3
)
 
(11
)
Net income (loss) attributable to Ameren Corporation
$
96

 
$
149

 
$
293

 
$
48

 
 
$
(145
)
 
$
95

 
$
302

 
$
37

Earnings per common share – basic – continuing operations
$
0.40

 
$
0.62

 
$
1.21

 
$
0.19

 
 
$
0.22

 
$
0.44

 
$
1.26

 
$
0.19

Earnings (loss) per common share – basic – discontinued operations
—

 
(0.01
)
 
—

 
0.01

 
 
(0.82
)
 
(0.05
)
 
(0.01
)
 
(0.04
)
Earnings (loss) per common share – basic
$
0.40

 
$
0.61

 
$
1.21

 
$
0.20

 
 
$
(0.60
)
 
$
0.39

 
$
1.25

 
$
0.15

Earnings per common share – diluted – continuing operations
$
0.40

 
$
0.62

 
$
1.20

 
$
0.19

 
 
$
0.22

 
$
0.44

 
$
1.25

 
$
0.19

Earnings (loss) per common share – diluted – discontinued operations
—

 
(0.01
)
 
—

 
0.01

 
 
(0.82
)
 
(0.05
)
 
(0.01
)
 
(0.04
)
Earnings (loss) per common share – diluted
$
0.40

 
$
0.61

 
$
1.20

 
$
0.20

 
 
$
(0.60
)
 
$
0.39

 
$
1.24

 
$
0.15

(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.

Ameren Missouri Quarter ended
 
Operating
Revenues
 
Operating
Income
 
Net Income
 (Loss)
 
Net Income (Loss)
Available
to Common
Stockholder
March 31, 2014
 
$
817

 
$
119

 
$
48

 
$
47

March 31, 2013
 
796

 
111

 
41

 
40

June 30, 2014
 
900

 
243

 
127

 
126

June 30, 2013
 
889

 
179

 
85

 
84

September 30, 2014
 
1,097

 
394

 
223

 
222

September 30, 2013
 
1,093

 
417

 
239

 
238

December 31, 2014
 
739

 
29

 
(5
)
 
(5
)
December 31, 2013
 
763

 
96

 
33

 
33


Ameren Illinois Quarter ended
 
Operating
Revenues
 
Operating
Income
 
Net Income
 
Net Income
Available
to Common
Stockholder
March 31, 2014
 
$
774

 
$
120

 
$
54

 
$
53

March 31, 2013
 
684

 
85

 
32

 
31

June 30, 2014
 
519

 
75

 
29

 
28

June 30, 2013
 
516

 
87

 
32

 
31

September 30, 2014
 
572

 
158

 
75

 
75

September 30, 2013
 
547

 
158

 
77

 
77

December 31, 2014
 
633

 
97

 
46

 
45

December 31, 2013
 
564

 
85

 
22

 
21

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, 2014, 2013, and 2012
(In millions)
2014
 
2013
 
2012
Operating revenues
$
—

 
$
—

 
$
—

Operating expenses
11

 
26

 
17

Operating loss
(11
)
 
(26
)
 
(17
)
Equity in earnings of subsidiaries
607

 
546

 
546

Interest income from affiliates
3

 
3

 
3

Total other income (expense), net
2

 
(5
)
 
(4
)
Interest charges
16

 
42

 
39

Income tax (benefit)
(2
)
 
(36
)
 
(27
)
Net Income Attributable to Ameren Corporation – Continuing Operations
587

 
512

 
516

Net Loss Attributable to Ameren Corporation – Discontinued Operations
(1
)
 
(223
)
 
(1,490
)
Net Income (Loss) Attributable to Ameren Corporation
$
586

 
$
289

 
$
(974
)
 
 
 
 
 
 
Net Income Attributable to Ameren Corporation – Continuing Operations
$
587

 
$
512

 
$
516

Other Comprehensive Income (Loss), Net of Taxes:
 
 
 
 
 
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $(7), $16, and $(6), respectively
(12
)
 
30

 
(8
)
Comprehensive Income from Continuing Operations Attributable to Ameren Corporation
575

 
542

 
508

Net Loss Attributable to Ameren Corporation – Discontinued Operations
(1
)
 
(223
)
 
(1,490
)
Other Comprehensive Income (Loss) from Discontinued Operations, Net of Income Taxes
—

 
(19
)
 
50

Comprehensive Loss from Discontinued Operations Attributable to Ameren Corporation
(1
)
 
(242
)
 
(1,440
)
Comprehensive Income (Loss) Attributable to Ameren Corporation
$
574

 
$
300

 
$
(932
)
SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED BALANCE SHEET
(In millions)
December 31, 2014
 
December 31, 2013
Assets:
 
 
 
Cash and cash equivalents
$
1

 
$
11

Advances to money pool
55

 
334

Accounts receivable – affiliates
28

 
18

Notes receivable – affiliates
94

 
9

Miscellaneous accounts and notes receivable
39

 
125

Current accumulated deferred income taxes, net
143

 
41

Other current assets
14

 
1

Total current assets
374

 
539

Investments in subsidiaries – continuing operations
6,680

 
6,336

Investments in subsidiaries – discontinued operations
(4
)
 
(5
)
Note receivable – ATXI
100

 
51

Accumulated deferred income taxes, net
264

 
570

Other assets
152

 
141

Total assets
$
7,566

 
$
7,632

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

 
$
425

Short-term debt
585

 
368

Accounts payable
—

 
119

Accounts payable – affiliates
88

 
4

Other current liabilities
52

 
20

Total current liabilities
725

 
936

Other deferred credits and liabilities
128

 
152

Total liabilities
853

 
1,088

Commitments and Contingencies (Notes 4 and 5)
 
 
 
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
5,617

 
5,632

Retained earnings
1,103

 
907

Accumulated other comprehensive income (loss)
(9
)
 
3

Total stockholders’ equity
6,713

 
6,544

Total liabilities and stockholders’ equity
$
7,566

 
$
7,632

SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED STATEMENT OF CASH FLOWS
For the Years Ended December 31, 2014, 2013, and 2012
(In millions)
2014
 
2013
 
2012
Net cash flows provided by operating activities
$
514

 
$
453

 
$
532

Cash flows from investing activities:
 
 
 
 
 
Money pool advances, net
279

 
(371
)
 
24

Notes receivable – affiliates, net
(134
)
 
(23
)
 
(20
)
Investments in subsidiaries
(280
)
 
(50
)
 
(2
)
Distributions from subsidiaries
215

 
1

 
21

Proceeds from note receivable – Marketing Company
95

 
6

 
—

Contributions to note receivable – Marketing Company
(89
)
 
(5
)
 
—

Other
(12
)
 
(3
)
 
(5
)
Net cash flows provided by (used in) investing activities
74

 
(445
)
 
18

Cash flows from financing activities:
 
 
 
 
 
Dividends on common stock
(390
)
 
(388
)
 
(382
)
Short-term debt, net
217

 
368

 
(148
)
Maturities of long-term debt
(425
)
 
—

 
—

Net cash flows used in financing activities
(598
)
 
(20
)
 
(530
)
Net change in cash and cash equivalents
$
(10
)
 
$
(12
)
 
$
20

Cash and cash equivalents at beginning of year
11

 
23

 
3

Cash and cash equivalents at end of year
$
1

 
$
11

 
$
23

 
 
 
 
 
 
Cash dividends received from consolidated subsidiaries
$
340

 
$
570

 
$
610

 
 
 
 
 
 
Noncash investing activity – divestiture
$
—

 
$
494

 
$
—

Noncash investing activity – investments in subsidiaries
(19
)
 
—

 
—

Noncash financing activity – dividends on common stock
—

 
—

 
(7
)
AMEREN CORPORATION (parent company only)
NOTES TO CONDENSED FINANCIAL STATEMENTS
December 31, 2014
NOTE 1 – 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.
Beginning in 2014, unrecognized tax benefits are recorded as a reduction to the deferred tax assets for net operating losses and tax credit carryforwards within "Accumulated deferred income taxes, net" on Ameren Corporation's (parent company only) balance sheets. At December 31, 2014, unrecognized tax benefits of $53 million were recorded in "Accumulated deferred income taxes, net" on Ameren Corporation's (parent company only) balance sheet. At December 31, 2013, unrecognized tax benefits of $53 million previously recorded in "Other deferred credits and liabilities" on Ameren Corporation's (parent company only) balance sheet were reclassified to "Accumulated deferred income taxes, net" for comparative purposes. See Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report for additional information.
Additional disclosures relating to the parent company financial statements are included within the combined notes under Part II, Item 8, of this report. See Note 1 – Summary of Significant Accounting Policies and Note 14 – Related Party Transactions under Part II, Item 8, of this report for information on the tax allocation agreement between Ameren (parent) and its subsidiaries.
NOTE 2 – 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).
NOTE 3 – LONG-TERM OBLIGATIONS
In May 2014, Ameren (parent) repaid at maturity $425 million of its 8.875% senior unsecured notes, plus accrued interest. The notes were repaid with proceeds from commercial paper issuances.
NOTE 4 – 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, guarantees, and letters of credit outstanding of Ameren Corporation (parent company only).
NOTE 5 – NEW AER DIVESTITURE AND DISCONTINUED OPERATIONS
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. In December 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 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 was reflected in "Accounts payable" on the December 31, 2013 Ameren Corporation (parent company only) Condensed Balance Sheet. In 2014, the receivable and payable were finalized and settled, along with certain contingent liabilities associated with the New AER divestiture, resulting in a net $13 million payment to IPH.
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, 2014, 2013, AND 2012
(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:
 
 
 
 
 
 
 
 
 
2014
$
18

 
$
36

 
$
4

 
$
37

 
$
21

2013
17

 
35

 
4

 
38

 
18

2012
20

 
30

 
2

 
35

 
17

Deferred tax valuation allowance:
 
 
 
 
 
 
 
 
 
2014
$
7

 
$
3

 
$
—

 
$
—

 
$
10

2013
2

 
5

 
—

 
—

 
7

2012
1

 
1

 
—

 
—

 
2

Ameren Missouri:
 
 
 
 
 
 
 
 
 
Deducted from assets – allowance for doubtful accounts:
 
 
 
 
 
 
 
 
 
2014
$
5

 
$
16

 
$
—

 
$
13

 
$
8

2013
5

 
16

 
—

 
16

 
5

2012
7

 
11

 
—

 
13

 
5

Deferred tax valuation allowance:
 
 
 
 
 
 
 
 
 
2014
$
1

 
$
—

 
$
—

 
$
—

 
$
1

2013
1

 
—

 
—

 
—

 
1

2012
1

 
—

 
—

 
—

 
1

Ameren Illinois:
 
 
 
 
 
 
 
 
 
Deducted from assets – allowance for doubtful accounts:
 
 
 
 
 
 
 
 
 
2014
$
13

 
$
20

 
$
4

 
$
24

 
$
13

2013
12

 
19

 
4

 
22

 
13

2012
13

 
19

 
2

 
22

 
12

Deferred tax valuation allowance:
 
 
 
 
 
 
 
 
 
2014
$
1

 
$
—

 
$
—

 
$
—

 
$
1

2013
1

 
—

 
—

 
—

 
1

2012
—

 
1

 
—

 
—

 
1

(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 the FERC. Ameren’s primary assets are its equity interests in its subsidiaries, including Ameren Missouri and Ameren Illinois. 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 rate-regulated electric and natural gas transmission and distribution businesses 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 was 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 813,000 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. ATXI is developing MISO-approved electric transmission projects, including the Illinois Rivers, Spoon River, and Mark Twain projects. Ameren is also pursuing reliability projects within Ameren Missouri's and Ameren Illinois' service territories as well as competitive electric transmission investment opportunities outside of these territories, including investments outside of MISO.
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 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 
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 without a traditional rate case proceeding. See Note 2 – Rate and Regulatory Matters for the regulatory assets and liabilities recorded at December 31, 2014 and 2013, related to the rate-adjustment mechanisms discussed below.
In Ameren Missouri’s and Ameren Illinois’ natural gas utility jurisdictions, changes in natural gas costs are reflected in billings to their natural gas utility customers through PGA clauses. The difference between actual natural gas costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either billed or refunded to natural gas utility customers in a subsequent period.
In Ameren Illinois’ retail electric utility jurisdiction, changes in purchased power and transmission service costs are reflected in billings to its electric utility customers through pass-through rate-adjustment clauses. The difference between actual purchased power and transmission service costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is 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 and purchased power costs, including transportation charges and revenues, net of off-system sales, greater or less than the amount set in base rates, subject to MoPSC prudence review. The difference between the actual amounts incurred for these items and the amounts recovered from Ameren Missouri customers' base rates is deferred as a regulatory asset or liability. The deferred amounts are either billed or refunded to electric utility customers in a subsequent period.
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.
Investments
Ameren and Ameren Missouri record investments held in Ameren Missouri's nuclear decommissioning trust fund at fair value. 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. In addition, Ameren and Ameren Missouri recognize a regulatory liability on their balance sheets for gains on investments held in the nuclear decommissioning trust fund. As of December 31, 2014, the nuclear decommissioning trust fund had cumulative gains.
Regulation
We are regulated by the MoPSC, the ICC, and the FERC. We defer certain costs as assets pursuant to actions of rate regulators or because of expectations that we will be able to recover such costs in rates charged to customers. We 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 solar rebate program tracker, a storm restoration cost tracker, and the MEEIA energy efficiency rider. Ameren Illinois' and ATXI's electric transmission rates are subject to formula ratemaking. Additionally, Ameren Illinois' electric distribution business participates in the performance-based formula ratemaking process established pursuant to the IEIMA. Ameren Illinois also 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.
Cash and Cash Equivalents 
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 
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 by 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 
Property and Plant, Net
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. If environmental expenditures are related to assets currently in use, as in the case of the installation of pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset. 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 2014, 2013, and 2012 ranged from 3% to 4% of the average depreciable cost.
Allowance for Funds Used During Construction 
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.
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 goodwill of $411 million at December 31, 2014, and 2013.
All of Ameren's and Ameren Illinois' goodwill at December 31, 2014 and 2013, was assigned to the Ameren Illinois reporting unit, which is also the Ameren Illinois reportable segment.
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, 2014. 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, 2014, 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, 2014, 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 30-year United States Treasury bonds;
•
a potential reduction in the FERC-allowed return on equity related to transmission services; and
•
actual and forecasted financial performance.
The goodwill assigned to the Ameren Illinois reporting unit on the December 31, 2014 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.
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 an impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets to the carrying value of the assets. If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount by which the carrying value 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 estimated fair value less cost to sell.
Asset Retirement Obligations 
Asset Retirement Obligations
We are required 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 expenditures 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 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. Ameren and Ameren Missouri are evaluating the potential effect of the EPA's new rule regarding the management and disposal of CCR on their AROs associated with ash ponds. See Note 15 – Commitments and Contingencies.
Asset removal costs accrued by our rate-regulated operations that do not constitute legal obligations are classified as regulatory liabilities.
Noncontrolling Interest 
Noncontrolling Interests
As of December 31, 2014 and 2013, Ameren’s noncontrolling interests included the preferred stock of Ameren Missouri and Ameren Illinois.
Revenue 
Operating Revenue
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.
Ameren Illinois participates in the performance-based formula ratemaking framework pursuant to the IEIMA. The IEIMA provides for an annual reconciliation of Ameren Illinois' electric delivery service revenue requirement. As of each balance sheet date, Ameren Illinois records its estimate of the electric delivery service revenue effect resulting from the reconciliation of the revenue requirement necessary to reflect the actual recoverable costs incurred for that year with the revenue requirement that was reflected in customer rates for that year. If the current year's revenue requirement is greater than the revenue requirement reflected in that year's customer rates, 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 reflected in that year's customer rates, 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
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's 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 recognize revenues once the resettlement amount is received.
Nuclear Fuel
Ameren Missouri’s cost of nuclear fuel is capitalized and then amortized to fuel expense on a unit-of-production basis. The cost is charged to "Operating Expenses – Fuel" in the statement of income.
Stock-Based Compensation 
Stock-based Compensation
Stock-based compensation cost is measured at the grant date based on the fair value of the award, net of an assumed forfeiture rate. 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
Ameren Missouri and Ameren Illinois collect certain excise taxes from customers that are levied on the sale or distribution of natural gas and electricity. Excise taxes are levied on Ameren Missouri's electric and natural gas businesses and on Ameren Illinois' natural gas business and are recorded gross in “Operating Revenues – Electric,” “Operating Revenues – Gas,” and “Operating Expenses – Taxes other than income taxes” on the statement of income or the statement of income and comprehensive income. Excise taxes for electric service in Illinois are levied on the customer and are therefore not included in Ameren Illinois' revenues and expenses. They are instead included in “Taxes accrued” on the balance sheet.
Unamortized Debt Discount, Premium, And Expense 
Unamortized Debt Discounts, Premiums, and Issuance Costs
Long-term debt discounts, premiums, and issuance costs are amortized over the lives of the related issuances. Credit facility fees are amortized over the credit facility term.
Income Taxes 
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 deferred tax liabilities that 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 through future customer rates of tax benefits related to the equity component of allowance for funds used during construction, as well as the effects of tax rate changes.
Investment tax credits used on tax returns for prior years have been deferred as a non-current liability. 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 rates for future lower income taxes associated with the amortization of the investment tax credits. See Note 13 – Income Taxes.
Ameren Missouri, Ameren Illinois, and all the other Ameren subsidiary companies are parties to a tax allocation agreement with Ameren (parent) 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 or refunded had the party been separately subject to tax. Any net benefit attributable to the parent is reallocated to the other parties. This reallocation is treated as a capital contribution to the party receiving the benefit.
Earnings Per Share 
Earnings per Share
Basic earnings per share is computed by dividing net income attributable to Ameren Corporation common stockholders by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed by dividing net income attributable to common stockholders 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 an Unrecognized Tax Benefit
In 2013, FASB issued additional authoritative accounting guidance, which became effective in 2014, 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. The objective of this guidance is to eliminate diversity in practice related to the presentation of certain unrecognized tax benefits. 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. Previously, unrecognized tax benefits were recorded in “Other deferred credits and liabilities” on Ameren's, Ameren Missouri's, and Ameren Illinois' respective balance sheets. Beginning in 2014, unrecognized tax benefits are recorded as a reduction to the deferred tax assets for net operating losses and tax credit carryforwards within "Accumulated deferred income taxes, net" on our balance sheets. Unrecognized tax benefits that exceed these carryforwards are recorded in “Other deferred credits and liabilities” on the respective balance sheets. At December 31, 2014, unrecognized tax benefits of $52 million, $- million, and $- million were recorded in "Accumulated deferred income taxes, net" on Ameren's, Ameren Missouri's, and Ameren Illinois' balance sheets, respectively. At December 31, 2013, unrecognized tax benefits of $84 million, $15 million, and $- million previously recorded in "Other deferred credits and liabilities" on Ameren's, Ameren Missouri's, and Ameren Illinois' respective balance sheets were reclassified to "Accumulated deferred income taxes, net" for comparative purposes. The implementation of the additional authoritative accounting guidance did not affect the Ameren Companies' results of operations or liquidity, as this guidance is presentation-related only.
Reporting Discontinued Operations and Disclosures of Components of an Entity
In 2014, FASB issued authoritative accounting guidance that changes the criteria for reporting and qualifying for discontinued operations. Under the new guidance, a component of an entity, or a group of components of an entity, that either meets the criteria to be classified as held for sale or is disposed of by sale or otherwise is required to be reported in discontinued operations if the disposal represents a strategic shift that had, or will have, a major effect on an entity's operations and financial results. The guidance includes expanded disclosure requirements for discontinued operations and additional disclosures about a disposal of an individually significant component of an entity that does not qualify for discontinued operations presentation. The guidance is effective for the Ameren Companies in the first quarter of 2015 for components that are classified as held for sale or disposed of on or after January 1, 2015. Early adoption is permitted, but only for disposals or classifications as held for sale that have not been reported in financial statements previously issued. Therefore, Ameren's existing discontinued operations are not subject to the new disclosure requirements. The guidance will not affect the Ameren Companies' results of operations, financial position, or liquidity, as this guidance is presentation-related only.
Revenue from Contracts with Customers
In 2014, FASB issued authoritative accounting guidance to clarify the principles for recognizing revenue and to develop a common revenue standard for GAAP. The guidance requires an entity to recognize an amount of revenue for the transfer of promised goods or services to customers that reflects the consideration which the entity expects to be entitled to in exchange for those goods or services. The guidance also requires additional disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The guidance will be effective for the Ameren Companies in the first quarter of 2017. The guidance allows entities to choose one of two transition methods, either by applying the guidance retrospectively to each reporting period presented or by recording a cumulative effect adjustment to retained earnings in the period of initial adoption. The Ameren Companies are currently assessing the impacts of this guidance on their results of operations, financial position, and liquidity, as well as the transition method that they will use to adopt the guidance.
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, 2014 and 2013:
 
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2014
 
 
 
 
 
 
Fuel(a)
 
$
134

 
$
—

 
$
134

Gas stored underground
 
16

 
111

 
127

Other materials and supplies
 
197

 
66

 
263

 
 
$
347

 
$
177

 
$
524

2013
 
 
 
 
 
 
Fuel(a)
 
$
144

 
$
—

 
$
144

Gas stored underground
 
17

 
110

 
127

Other materials and supplies
 
191

 
64

 
255

 
 
$
352

 
$
174

 
$
526

(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 used during 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Ameren Missouri
7
%
 
8
%
 
8
%
Ameren Illinois
2
%
 
8
%
 
9
%
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, 2014 and 2013:
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
 
Balance at December 31, 2012
$
346

 
$
3

 
$
349

 
Liabilities settled
(1
)
 
(a)

 
(1
)
 
Accretion in 2013(b)
19

 
(a)

 
19

 
Change in estimates(c)
2

 
(a)

 
2

 
Balance at December 31, 2013
$
366

 
$
3

(d) 
$
369

 
Liabilities incurred
2

 
—

 
2

 
Liabilities settled
(2
)
 
(a)

 
(2
)
 
Accretion in 2014(b)
21

 
(a)

 
21

 
Change in estimates(c)(e)
2

 
4

 
6

 
Balance at December 31, 2014
$
389

 
$
7

(d) 
$
396

 

(a)
Less than $1 million.
(b)
Accretion expense was recorded as an increase to regulatory assets at Ameren Missouri and Ameren Illinois.
(c)
Ameren Missouri changed its fair value estimates for asbestos removal in 2013 and 2014 and for certain CCR facilities in 2013.
(d)
Included in “Other deferred credits and liabilities” on the balance sheet.
(e)
Ameren Illinois changed its fair value estimate for asbestos removal in 2014.
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 December 31, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Ameren Missouri
$
151

 
$
152

 
$
139

Ameren Illinois
64

 
61

 
54

Ameren
$
215

 
$
213

 
$
193

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, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Net income (loss) attributable to Ameren Corporation:
 
 
 
 
 
Continuing operations
$
587

 
$
512

 
$
516

Discontinued operations
(1
)
 
(223
)
 
(1,490
)
Net income (loss) attributable to Ameren Corporation
$
586

 
$
289

 
$
(974
)
 
 
 
 
 
 
Average common shares outstanding – basic
242.6

 
242.6

 
242.6

Assumed settlement of performance share units
1.8

 
1.9

 
0.4

Average common shares outstanding – diluted
244.4

 
244.5

 
243.0

 
 
 
 
 
 
Earnings (loss) per common share – basic:
 
 
 
 
 
Continuing operations
$
2.42

 
$
2.11

 
$
2.13

Discontinued operations
—

 
(0.92
)
 
(6.14
)
Earnings (loss) per common share – basic
$
2.42

 
$
1.19

 
$
(4.01
)
 
 
 
 
 
 
Earnings (loss) per common share – diluted:
 
 
 
 
 
Continuing operations
$
2.40

 
$
2.10

 
$
2.13

Discontinued operations
—

 
(0.92
)
 
(6.14
)
Earnings (loss) per common share – diluted
$
2.40

 
$
1.18

 
$
(4.01
)

Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] 
Supplemental Cash Flow Information
The following table presents additional information regarding Ameren's consolidated statement of cash flows for the years ended December 31, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Cash paid (refunded) during the year:
Interest
 
 
 
 
 
Continuing operations(a)
$
333

 
$
362

 
$
384

Discontinued operations(b)
—

 
31

 
49

 
$
333

 
$
393

 
$
433

 
 
 
 
 
 
Income taxes, net
 
 
 
 
 
Continuing Operations
$
(41
)
 
$
116

 
$
10

Discontinued Operations
14

 
(108
)
 
(9
)
 
$
(27
)
 
$
8

 
$
1

(a)
Net of $18 million, $20 million, and $17 million capitalized, respectively.
(b)
Net of $- million, $17 million, and $13 million capitalized, respectively.
Rate And Regulatory Matters (Tables)
Schedule Of Regulatory Assets And Liabilities
The following table presents our regulatory assets and regulatory liabilities at December 31, 2014 and 2013:
 
 
2014
 
2013
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Current regulatory assets:
 
 
 
 
 
 
 
 
 
 
 
 
 
Under-recovered FAC(a)(b)
 
$
128

 
$
—

 
$
128

 
 
$
104

 
$
—

 
$
104

Under-recovered Illinois electric power costs(c)
 
—

 
2

 
2

 
 
—

 
1

 
1

Under-recovered PGA(c)
 
—

 
20

 
20

 
 
—

 
1

 
1

MTM derivative losses(d)
 
32


42

 
74

 
 
14

 
36

 
50

Energy efficiency riders(e)

 
3

 
—

 
3

 
 
—

 
—

 
—

IEIMA revenue requirement reconciliation(a)(f)
 
—

 
65

 
65

 
 
—

 
—

 
—

FERC revenue requirement reconciliation(a)(g)

 
—

 
—

 
3

 
 
—

 
—

 
—

Total current regulatory assets
 
$
163

 
$
129

 
$
295

 
 
$
118

 
$
38

 
$
156

Noncurrent regulatory assets:
 
 
 
 
 
 
 
 
 
 
 
 
 
Pension and postretirement benefit costs(h)
 
$
148

 
$
275

 
$
423

 
 
$
44

 
$
140

 
$
184

Income taxes(i)
 
253

 
3

 
256

 
 
230

 
7

 
237

Asset retirement obligations(j)
 
—

 
5

 
5

 
 
—

 
5

 
5

Callaway costs(a)(k)
 
36

 
—

 
36

 
 
40

 
—

 
40

Unamortized loss on reacquired debt(a)(l)
 
72

 
80

 
152

 
 
77

 
74

 
151

Contaminated facilities costs(m)
 
—

 
251

 
251

 
 
—

 
271

 
271

MTM derivative losses(d)
 
14


144

 
158



8

 
118

 
126

Storm costs(n)
 
—

 
3

 
3

 
 
5

 
3

 
8

Demand-side costs before the MEEIA implementation(a)(o)
 
44

 
—

 
44

 
 
58

 
—

 
58

Workers’ compensation claims(p)
 
7

 
7

 
14

 
 
6

 
6

 
12

Credit facilities fees(q)
 
5

 
—

 
5

 
 
5

 
—

 
5

Common stock issuance costs(r)
 
2

 
—

 
2

 
 
4

 
—

 
4

Construction accounting for pollution control equipment(a)(s)
 
21

 
—

 
21

 
 
22

 
—

 
22

Solar rebate program(a)(t)
 
88

 
—

 
88

 
 
27

 
—

 
27

IEIMA revenue requirement reconciliation(a)(f)
 
—

 
101

 
101

 
 
—

 
65

 
65

FERC revenue requirement reconciliation(a)(g)
 
—

 
8

 
12

 
 
—

 
—

 
5

Other(u)
 
5

 
6

 
11

 
 
8

 
12

 
20

Total noncurrent regulatory assets
 
$
695

 
$
883

 
$
1,582

 
 
$
534

 
$
701

 
$
1,240

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

 
$
—

 
$
—

 
 
$
26

 
$
—

 
$
26

Over-recovered Illinois electric power costs(c)
 
—

 
26

 
26

 
 
—

 
51

 
51

Over-recovered PGA(c)
 
2

 
25

 
27

 
 
5

 
29

 
34

MTM derivative gains(d)
 
16

 
1

 
17


 
26

 
1

 
27

Wholesale distribution refund(v)
 
—

 
—

 
—

 
 
—

 
13

 
13

IEIMA revenue requirement reconciliation(f)
 
—

 
—

 
—

 
 
—

 
65

 
65

FERC revenue requirement reconciliation(g)
 
—

 
11

 
11

 
 
—

 
—

 
—

Refund reserves for FERC orders and audit findings(w)
 
—

 
21

 
25

 
 
—

 
—

 
—

Total current regulatory liabilities
 
$
18

 
$
84

 
$
106

 
 
$
57

 
$
159

 
$
216

Noncurrent regulatory liabilities:
 
 
 
 
 
 
 
 
 
 
 
 
 
Income taxes(x)
 
$
41

 
$
14

 
$
55

 
 
$
37

 
$
3

 
$
40

Uncertain tax positions tracker(y)
 
7

 
—

 
7

 
 
1

 
—

 
1

Removal costs(z)
 
886

 
643

 
1,529

 
 
828

 
610

 
1,438

Asset retirement obligation(j)
 
182

 
—

 
182

 
 
146

 
—

 
146

Bad debt riders(aa)
 
—

 
7

 
7

 
 
—

 
8

 
8

Pension and postretirement benefit costs tracker(ab)
 
24

 
—

 
24

 
 
15

 
—

 
15

Energy efficiency riders(e)
 
—

 
39

 
39

 
 
3

 
33

 
36

FERC revenue requirement reconciliation(g)
 
—

 
—

 
—

 
 
—

 
10

 
10

Other(ac)
 
7

 
—

 
7

 
 
11

 
—

 
11

Total noncurrent regulatory liabilities
 
$
1,147

 
$
703

 
$
1,850

 
 
$
1,041

 
$
664

 
$
1,705

(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)
The Ameren Missouri balance relates to the MEEIA. Beginning in January 2014, a MEEIA rider allowed Ameren Missouri to collect from or refund to customers any annual difference in the actual amounts incurred and the amounts collected from customers for the MEEIA program costs and its lost revenues. Under the MEEIA rider, collections from or refunds to customers occur one year after the program costs and lost revenues are incurred. The Ameren Illinois balance relates to a regulatory tracking mechanism to recover its electric and natural gas costs associated with developing, implementing, and evaluating customer energy efficiency and demand response programs. Any under-recovery or over-recovery will be collected from or refunded to customers over the 12 months following the plan year.
(f)
The difference between Ameren Illinois' annual revenue requirement calculated under the IEIMA's performance-based formula ratemaking framework and the revenue requirement included in customer rates for that year. Subject to ICC approval, these amounts will be collected from or refunded to customers within two years.
(g)
Ameren Illinois' and ATXI's annual revenue requirement reconciliation adjustments calculated pursuant to the FERC's electric transmission formula ratemaking framework. The under-recovery or over-recovery will be recovered from or refunded to customers within two years.
(h)
These costs are being amortized in proportion to the recognition of prior service costs (credits) and actuarial losses (gains) attributable to Ameren’s pension plan and postretirement benefit plans. See Note 11 – Retirement Benefits for additional information.
(i)
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.
(j)
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.
(k)
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.
(l)
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.
(m)
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.
(n)
Ameren Missouri's actual storm costs that exceed the normalized storm costs for rate purposes. As approved by the December 2012 MoPSC electric rate order, the 2006, 2007, and 2008 storm costs were amortized through December 2014. The Ameren Illinois balance includes 2013 storm costs deferred in accordance with the IEIMA. These costs are being amortized over a five-year period beginning in 2013.
(o)
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.The amortization period for costs incurred from August 2012 through December 2012 will be determined in the July 2014 electric rate case.
(p)
The period of recovery will depend on the timing of actual expenditures.
(q)
Ameren Missouri’s costs incurred to enter into and maintain the 2012 Missouri Credit Agreement. Additional costs were incurred in December 2014 to amend and restate the 2012 Missouri Credit Agreement. These costs are being amortized over the life of the credit facility, ending in December 2019, to construction work in progress, which will be depreciated when assets are placed into service.
(r)
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.
(s)
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 was included in customer rates. These costs will be amortized over the expected life of the Sioux energy center, which is currently through 2033.
(t)
Costs associated with Ameren Missouri's solar rebate program beginning in August 2012 to fulfill its renewable energy portfolio requirement. The amortization period for these costs will be three years, commencing with the effectiveness of Ameren Missouri's current July 2014 electric rate case.
(u)
The Ameren Illinois balance includes Ameren Illinois Merger integration and optimization costs, which are being 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. 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.
(v)
Estimated refund to wholesale electric customers as of December 31, 2013. See 2011 Wholesale Distribution Rate Case above.
(w)
Estimated refunds to transmission customers related to FERC orders and audit findings. In regards to the FERC orders, see Ameren Illinois Electric Transmission Rate Refund and FERC Complaint Cases above.
(x)
Unamortized portion of investment tax credits and federal excess deferred taxes. The unamortized portion of investment tax credits and the federal excess deferred taxes are being amortized over the expected life of the underlying assets.
(y)
The tracker is amortized over three years, beginning from the date the amounts are included in rates. See Note 13 - Income Taxes for additional information.
(z)
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.
(aa)
A regulatory tracking mechanism for the difference between the level of bad debt incurred by Ameren Illinois under GAAP and the level of such costs included in electric and natural gas rates. The over-recovery relating to 2012 was refunded to customers from June 2013 through May 2014. The over-recovery relating to 2013 is being refunded to customers from June 2014 through May 2015. The over-recovery relating to 2014 will be refunded to customers from June 2015 through May 2016.
(ab)
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 the July 2014 electric rate case.
(ac)
Balance 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 balance also includes a regulatory tracking mechanism at Ameren Missouri for the difference between the level of storm costs incurred in a particular year and the level of such costs built into rates. The amortization periods for these over-recoveries will be determined in the July 2014 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, 2014 and 2013:
 
 
Ameren
Missouri(a)
 
Ameren
Illinois
 
Other
 
Ameren(a)
2014
 
 
 
 
 
 
 
 
Property and plant, at original cost:
 
 
 
 
 
 
 
 
Electric
 
$
17,052

 
$
6,517

 
$
344

 
$
23,913

Natural gas
 
431

 
1,854

 
—

 
2,285

 
 
17,483

 
8,371

 
344

 
26,198

Less: Accumulated depreciation and amortization
 
7,086

 
2,422

 
251

 
9,759

 
 
10,397

 
5,949

 
93

 
16,439

Construction work in progress:
 
 
 
 
 
 
 
 
Nuclear fuel in process
 
209

 
—

 
—

 
209

Other
 
261

 
216

 
299

 
776

Property and plant, net
 
$
10,867

 
$
6,165

 
$
392

 
$
17,424

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


(a)
Amounts in Ameren and Ameren Missouri include two CTs under separate capital lease agreements. The gross cumulative asset value of those agreements was $233 million and $228 million at December 31, 2014 and 2013, respectively. The total accumulated depreciation associated with the two CTs was $66 million and $56 million at December 31, 2014 and 2013, 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, 2014 and 2013, the carrying value of these debt securities was $294 million and $299 million, respectively.
Accrued Capital Expenditures 
The following table provides accrued capital and nuclear fuel expenditures at December 31, 2014, 2013, and 2012, which represent noncash investing activity excluded from the accompanying statements of cash flows:
 
Ameren(a)
 
Ameren
Missouri
 
Ameren
Illinois
Accrued capital expenditures:
 
 
 
 
 
2014
$
181

 
$
72

 
$
59

2013
175

 
74

 
86

2012
107

 
63

 
37

Accrued nuclear fuel expenditures:
 
 
 
 
 
2014
13

 
13

 
(b)

2013
8

 
8

 
(b)

2012
8

 
8

 
(b)


(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)
Not applicable.
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 (the amount being each borrower's "Borrowing Sublimit"):
 
 
2012 Missouri Credit Agreement
2012 Illinois
Credit Agreement
Ameren
 
$
700

$
500

Ameren Missouri
 
800

(a)

Ameren Illinois
 
  (a)

800

(a)
Not applicable.
Schedule of Commercial Paper 
The following table summarizes the borrowing activity and relevant interest rates under Ameren Missouri's and Ameren Illinois' commercial paper program, for the years ended December 31, 2014 and 2013:
 
 
Ameren (parent)
Ameren Missouri
Ameren Illinois
Ameren Consolidated
2014
 
 
 
 
 
 
Average daily commercial paper outstanding
 
$
423

 
$
110

$
165

$
639

Outstanding borrowings at period-end
 
585

 
97

32

714

Weighted-average interest rate
 
0.36
%
 
0.38
%
0.32
%
0.36
%
Peak commercial paper during period(a)
 
$
625

 
$
495

$
300

$
910

Peak interest rate
 
0.75
%
 
0.70
%
0.60
%
0.75
%
2013
 
 
 
 
 
 
Average daily commercial paper outstanding
 
$
54

 
$
—

$
—

$
54

Outstanding borrowings at period-end
 
368

 
—

—

368

Weighted-average interest rate
 
0.56
%
 
—
%
—
%
0.56
%
Peak commercial paper during period(a)
 
$
368

 
$
—

$
—

$
368

Peak interest rate
 
0.85
%
 
—
%
—
%
0.85
%

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, 2014 and 2013:
 
2014
 
2013
Ameren (Parent):
 
 
 
8.875% Senior unsecured notes due 2014
$
—

 
$
425

Less: Maturities due within one year
—

 
(425
)
Long-term debt, net
$
—

 
$
—

Ameren Missouri:
 
 
 
Senior secured notes:(a)
 
 
 
5.50% Senior secured notes due 2014
—

 
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

3.50% Senior secured notes due 2024
350

 
—

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)

 
(e)

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) due 2022
54

 
59

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

 
240

Total long-term debt, gross
4,005

 
3,764

Less: Unamortized discount and premium
(6
)
 
(7
)
Less: Maturities due within one year
(120
)
 
(109
)
Long-term debt, net
$
3,879

 
$
3,648

 
2014
 
2013
Ameren Illinois:
 
 
 
Senior secured notes:
 
 
 
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

3.25% Senior secured notes due 2025(g)
300

 
—

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

 
280

4.30% Senior secured notes due 2044(g)
250

 
—

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

 
32

5.70% 1994A Series due 2024(j)
(j)

 
36

5.95% 1993 Series C-1 due 2026(k)
—

 
35

5.70% 1993 Series C-2 due 2026(k)
—

 
8

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

 
17

5.40% 1998A Series due 2028(j)
—

 
19

5.40% 1998B Series due 2028(j)
—

 
33

Fair-market value adjustments
—

 
4

Total long-term debt, gross
2,246

 
1,863

Less: Unamortized discount and premium
(5
)
 
(7
)
Less: Maturities due within one year
—

 
—

Long-term debt, net
$
2,241

 
$
1,856

Ameren consolidated long-term debt, net
$
6,120

 
$
5,504

(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 senior secured notes currently outstanding, 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)
The interest rates, and the periods during which such rates apply, vary depending on our selection of defined rate modes. Maximum interest rates could reach 18% depending on the series of bonds. The average interest rates for 2014 and 2013 were as follows:
    
 
2014
 
2013
Ameren Missouri 1992 Series due 2022
0.10%
 
0.17%
Ameren Missouri 1998 Series A due 2033
0.26%
 
0.34%
Ameren Missouri 1998 Series B due 2033
0.27%
 
0.33%
Ameren Missouri 1998 Series C due 2033
0.26%
 
0.34%
Ameren Illinois 1993 Series B-1 due 2028
0.21%
 
0.14%

(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 Ameren Illinois could cause these notes to become unsecured at any time by redeeming the pollution control bonds 5.90% Series 1993 due 2023 (of which less than $1 million remains outstanding). Ameren Illinois may resecure these notes if it chooses.
(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 senior secured notes currently outstanding, we do not expect the mortgage bond lien protection associated with these notes to fall away until 2024.
(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. Less than $1 million principal amount of the bonds remain outstanding.
(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. Less than $1 million principal amount of the bonds remain outstanding.
(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, 2014:
 
 
 Ameren
Missouri(a)
 
 Ameren
Illinois(a)
 
Ameren
Consolidated
2015
 
$
120

 
$
—

 
$
120

2016
 
266

 
129

 
395

2017
 
431

 
250

 
681

2018
 
383

 
457

 
840

2019
 
581

 
—

 
581

Thereafter
 
2,224

 
1,410

 
3,634

Total
 
$
4,005

 
$
2,246

 
$
6,251

(a)
Excludes unamortized discount and premium of $6 million and $5 million at Ameren Missouri and Ameren Illinois, respectively.
Schedule Of Outstanding Preferred Stock 
 
 
 
Redemption Price(per share)
 
2014
 
2013
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, dividend coverage ratios, and bonds and preferred stock issuable as of December 31, 2014, at an assumed interest rate of 5% and dividend rate of 6%.
 
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
4.3

$
3,605

  
>2.5
115.1

$
2,568

Ameren Illinois
>2.0
6.4

3,358

(d) 
>1.5
2.7

208

(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 $832 million and $204 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.
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
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, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
 
Ameren:(a)
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
34

 
$
37

 
$
36

 
Interest income on industrial development revenue bonds
27

 
27

 
28

 
Interest income
10

(b) 
3

 
4

(d) 
Other
8

(c) 
2

 
2

 
Total miscellaneous income
$
79

 
$
69

 
$
70

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
10

 
$
12

 
$
24

(e) 
Other
12

 
14

 
13

 
Total miscellaneous expense
$
22

 
$
26

 
$
37

 
Ameren Missouri:
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
32

 
$
31

 
$
31

 
Interest income on industrial development revenue bonds
27

 
27

 
28

 
Interest income
1

 
—

 
4

(d) 
Total miscellaneous income
$
60

 
$
58

 
$
63

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
6

 
$
4

 
$
9

 
Other
6

 
7

 
5

 
Total miscellaneous expense
$
12

 
$
11

 
$
14

 
Ameren Illinois:
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
Allowance for equity funds used during construction
$
2

 
$
6

 
$
5

 
Interest income
7

(b) 
2

 
—

 
Other
8

(c) 
2

 
2

 
Total miscellaneous income
$
17

 
$
10

 
$
7

 
Miscellaneous expense:
 
 
 
 
 
 
Donations
$
4

 
$
4

 
$
11

(e) 
Other
4

 
5

 
6

 
Total miscellaneous expense
$
8

 
$
9

 
$
17

 
(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
Includes Ameren Illinois' interest income received in 2014 relating to the 2013 and 2014 IEIMA revenue requirement reconciliation regulatory assets.
(c)
Includes Ameren Illinois' income earned in 2014 from customer-requested construction.
(d)
Includes Ameren Missouri's interest income 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.
(e)
Includes Ameren Illinois' one-time $7.5 million contribution to the Illinois Science and Energy Innovation Trust pursuant to the IEIMA as a result of Ameren Illinois' 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, 2014 and 2013. As of December 31, 2014, these contracts ran through October 2017, October 2019, May 2032, and October 2016 for fuel oils, natural gas, power, and uranium, respectively.
  
Quantity (in millions, except as indicated)
 
2014
2013
Commodity
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Fuel oils (in gallons)(a)
50
(b)
50
66
(b)
66
Natural gas (in mmbtu)
28
108
136
28
108
136
Power (in megawatthours)
1
11
12
3
11
14
Uranium (pounds in thousands)
332
(b)
332
796
(b)
796

(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 commodity contracts, none of which were designated as hedging instruments, as of December 31, 2014 and 2013:
 
Balance Sheet Location
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2014
 
 
 
 
 
 
 
Fuel oils
Other current assets
$
2

$
—

$
2

Natural gas
Other current assets
 
1

 
1

 
2

Power
Other current assets
 
15

 
—

 
15

 
Total assets
$
18

$
1

$
19

Fuel oils
Other current liabilities
$
22

$
—

$
22

 
Other deferred credits and liabilities
 
7

 
—

 
7

Natural gas
MTM derivative liabilities
 
(a)

 
31

 
(a)

 
Other current liabilities
 
6

 
—

 
37

 
Other deferred credits and liabilities
 
6

 
13

 
19

Power
MTM derivative liabilities
 
(a)

 
11

 
(a)

 
Other current liabilities
 
3

 
—

 
14

 
Other deferred credits and liabilities
 
—

 
131

 
131

Uranium
Other current liabilities
 
2

 
—

 
2

 
Total liabilities
$
46

$
186

$
232

2013
 
 
 
 
 
 
 
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

Fuel oils
Other current liabilities
$
2

$
—

$
2

 
Other deferred credits and liabilities
 
1

 
—

 
1

Natural gas
MTM derivative liabilities
 
(a)

 
27

 
(a)

 
Other current liabilities
 
5

 
—

 
32

 
Other deferred credits and liabilities
 
6

 
19

 
25

Power
MTM derivative liabilities
 
(a)

 
9

 
(a)

 
Other current liabilities
 
4

 
—

 
13

 
Other deferred credits and liabilities
 
—

 
99

 
99

Uranium
Other current liabilities
 
5

 
—

 
5

 
Other deferred credits and liabilities
 
1

 
—

 
1

 
Total liabilities
$
24

$
154

$
178

(a)
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, 2014 and 2013:
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2014
 
 
 
 
 
 
Fuel oils derivative contracts(a)
$
(29
)
$
—

$
(29
)
Natural gas derivative contracts(b)
 
(11
)
 
(43
)
 
(54
)
Power derivative contracts(c)
 
12

 
(142
)
 
(130
)
Uranium derivative contracts(d)
 
(2
)
 
—

 
(2
)
2013
 
 
 
 
 
 
Fuel oils derivative contracts
$
2

$
—

$
2

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

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

 
(6
)

(a)
Represents net losses associated with fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s rail transportation surcharges for coal through December 2017. Current losses deferred as regulatory assets include $21 million and $21 million at Ameren and Ameren Missouri, 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 October 2018 at Ameren Illinois. Current gains deferred as regulatory liabilities include $2 million, $1 million, and $1 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively. Current losses deferred as regulatory assets include $37 million, $6 million, and $31 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively.
(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. Current gains deferred as regulatory liabilities include $15 million and $15 million at Ameren and Ameren Missouri, respectively. Current losses deferred as regulatory assets include $14 million, $3 million, and $11 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively.
(d)
Represents net losses associated with uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri's uranium requirements through December 2016. Current losses deferred as regulatory assets include $2 million and $2 million at Ameren and Ameren Missouri, respectively.
Derivative Instruments With Credit Risk-Related Contingent Features 
The following table presents, as of December 31, 2014, 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 netting arrangements assuming (1) the credit risk-related contingent features underlying these arrangements were triggered on December 31, 2014, 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)
Ameren Missouri
$
96

 
$
4

 
$
88

Ameren Illinois
74

 
—

 
71

Ameren
$
170

 
$
4

 
$
159

(a)
Prior to consideration of master netting arrangements and including NPNS and other accrual contract exposures.
(b)
As collateral requirements with certain counterparties are based on master netting arrangements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such arrangements.
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, 2014 and 2013:
 
 
 
 
Gross Amounts Not Offset on the Balance Sheet
 
 
Commodity Contracts Eligible to be Offset
 
Gross Amounts Recognized on the Balance Sheet
 
Derivative Instruments
 
Cash Collateral Received/Posted(a)
 
Net
Amount
2014
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
$
18

$
5

$
—

$
13

Ameren Illinois
 
1

 
—

 
—

 
1

Ameren
$
19

$
5

$
—

$
14

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
$
46

$
5

$
5

$
36

Ameren Illinois
 
186

 
—

 
—

 
186

Ameren
$
232

$
5

$
5

$
222

2013
 
 
 
 
 
 
 
 
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

(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, 2014:
 
 
Fair Value
 
 
 
 
Weighted
 
 
Assets
Liabilities
 
Valuation Technique(s)
Unobservable Input
Range
Average
Level 3 Derivative asset and liability – commodity contracts(a):
 
 
 
Ameren
Fuel oils
$
2

$
(8
)
 
Option model
Volatilities(%)(b)
3 - 39
32
 
 
 
 
 
Discounted cash flow
Ameren Missouri credit risk(%)(b)(c)
0.43
(d)
 
 
 
 
 
 
Escalation rate(%)(e)(f)
5
(d)
 
Natural Gas
1

(2
)
 
Option model
Volatilities(%)(b)
31 - 144
63
 



 

Nodal basis($/mmbtu)(e)
(0.40) - 0
(0.20)
 



 
Discounted cash flow
Nodal basis($/mmbtu)(e)
(0.40) - 0.10
(0.20)
 



 

Counterparty credit risk(%)(b)(c)
0.43 - 13
3
 



 

Ameren Missouri and Ameren Illinois credit risk(%)(b)(c)
0.43
(d)
 
Power(g)
11

(144
)
 
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(h)
27 - 50
32
 
 
 
 
 
 
Estimated auction price for FTRs($/MW)(e)
(1,833) - 2,743
171
 
 
 
 
 
 
Nodal basis($/MWh)(e)
(6) - 0
(2)
 
 
 
 
 
 
Counterparty credit risk(%)(b)(c)
0.26
(d)
 
 
 
 
 
 
Ameren Missouri and Ameren Illinois credit risk(%)(b)(c)
0.43
(d)
 
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(e)
4 - 5
4
 
 
 
 
 
 
Escalation rate(%)(e)(i)
0 - 1
1
 
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(e)
5 - 7
6
 
Uranium
—

(2
)
 
Discounted cash flow
Average forward uranium pricing($/pound)(e)
35 - 40
36
Ameren Missouri
Fuel oils
$
2

$
(8
)
 
Option model
Volatilities(%)(b)
3 - 39
32
 
 
 
 
 
Discounted cash flow
Ameren Missouri credit risk(%)(b)(c)
0.43
(d)
 
 
 
 
 
 
Escalation rate(%)(e)(f)
5
(d)
 
Natural Gas
—

(1
)
 
Option model
Volatilities(%)(b)
31 - 144
53
 



 

Nodal basis($/mmbtu)(e)
(0.40) - 0
(0.30)
 



 
Discounted cash flow
Nodal basis($/mmbtu)(e)
(0.10)
(d)
 



 

Counterparty credit risk(%)(b)(c)
0.57 - 13
5
 



 

Ameren Missouri credit risk(%)(b)(c)
0.43
(d)
 
Power(g)
11

(2
)
 
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(b)
27 - 50
32
 
 
 
 
 
 
Estimated auction price for FTRs($/MW)(e)
(1,833) - 2,743
171
 
 
 
 
 
 
Counterparty credit risk(%)(b)(c)
0.26
(d)
 
 
 
 
 
 
Ameren Missouri credit risk(%)(b)(c)
0.43
(d)
 
Uranium
—

(2
)
 
Discounted cash flow
Average forward uranium pricing($/pound)(e)
35 - 40
36
Ameren Illinois
Natural Gas
$
1

$
(1
)
 
Option model
Volatilities(%)(b)
50 - 144
94
 



 

Nodal basis($/mmbtu)(e)
(0.10) - 0
(0.10)
 



 
Discounted cash flow
Nodal basis($/mmbtu)(e)
(0.40) - 0.10
(0.20)
 



 

Counterparty credit risk(%)(b)(c)
0.43 - 2
0.83
 



 

Ameren Illinois credit risk(%)(b)(c)
0.43
(d)
 
 
Fair Value
 
 
 
 
Weighted
 
 
Assets
Liabilities
 
Valuation Technique(s)
Unobservable Input
Range
Average
 
Power(g)
—

(142
)
 
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(e)
27 - 38
32
 
 
 
 
 
 
Nodal basis($/MWh)(e)
(6) - 0
(2)
 
 
 
 
 
 
Ameren Illinois credit risk(%)(b)(c)
0.43
(d)
 
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(e)
4 - 5
4
 
 
 
 
 
 
Escalation rate(%)(e)(i)
0 - 1
1
 
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(e)
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 lower (higher) fair value measurement.
(c)
Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(d)
Not applicable.
(e)
Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(f)
Escalation rate applies to fuel oil prices 2017 and beyond.
(g)
Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2018. Valuations beyond 2018 use fundamentally modeled pricing by month for peak and off-peak demand.
(h)
The balance at Ameren is comprised of Ameren Missouri and Ameren Illinois power contracts, which respond differently to unobservable input changes due to their opposing positions. As such, refer to the power sensitivity analysis for each company above.
(i)
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, 2013:
 
 
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)
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 Missouri and 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
 
Uranium
—

(6
)
 
Discounted cash flow
Average forward uranium 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 forward uranium 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 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.
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, 2014:
 
 
 
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
 
$
—

 
$
—

 
$
2

 
$
2

 
 
Natural gas
 
—

 
1

 
1

 
2

 
 
Power
 
—

 
4

 
11

 
15

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
5

 
$
14

 
$
19

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
364

 
—

 
—

 
364

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
63

 
—

 
63

 
 
Municipal bonds
 
—

 
2

 
—

 
2

 
 
U.S. treasury and agency securities
 
—

 
102

 
—

 
102

 
 
Asset-backed securities
 
—

 
10

 
—

 
10

 
 
Other
 
—

 
5

 
—

 
5

 
 
Total nuclear decommissioning trust fund
 
$
365

 
$
182

 
$
—

 
$
547

(b) 
 
Total Ameren
 
$
365

 
$
187

 
$
14

 
$
566

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

 
$
—

 
$
2

 
$
2

 
 
Natural gas
 
—

 
1

 
—

 
1

 
 
Power
 
—

 
4

 
11

 
15

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
5

 
$
13

 
$
18

 
 
 
 
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
 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
364

 
—

 
—

 
364

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
63

 
—

 
63

 
 
Municipal bonds
 
—

 
2

 
—

 
2

 
 
U.S. treasury and agency securities
 
—

 
102

 
—

 
102

 
 
Asset-backed securities
 
—

 
10

 
—

 
10

 
 
Other
 
—

 
5

 
—

 
5

 
 
Total nuclear decommissioning trust fund
 
$
365

 
$
182

 
$
—

 
$
547

(b) 
 
Total Ameren Missouri
 
$
365

 
$
187

 
$
13

 
$
565

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

 
$
—

 
$
1

 
$
1

 
Liabilities:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
21

 
$
—

 
$
8

 
$
29

 
 
Natural gas
 
1

 
53

 
2

 
56

 
 
Power
 
—

 
1

 
144

 
145

 
 
Uranium
 
—

 
—

 
2

 
2

 
 
Total Ameren
 
$
22

 
$
54

 
$
156

 
$
232

 
Ameren Missouri
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
21

 
$
—

 
$
8

 
$
29

 
 
Natural gas
 
1

 
10

 
1

 
12

 
 
Power
 
—

 
1

 
2

 
3

 
 
Uranium
 
—

 
—

 
2

 
2

 
 
Total Ameren Missouri
 
$
22

 
$
11

 
$
13

 
$
46

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

 
$
43

 
$
1

 
$
44

 
 
Power
 
—

 
—

 
142

 
142

 
 
Total Ameren Illinois
 
$
—

 
$
43

 
$
143

 
$
186

 
(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 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

 
 
 
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
 
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.
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 for the year ended December 31, 2014:
  
 
Net Derivative Commodity Contracts
  
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
5

$
(a)

$
5

Realized and unrealized gains (losses) included in regulatory assets/liabilities:
 
(9
)
 
(a)

 
(9
)
Settlements
 
(2
)
 
(a)

 
(2
)
Ending balance at December 31, 2014
$
(6
)
$
(a)

$
(6
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014
$
(6
)
$
(a)

$
(6
)
Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
—

$
—

$
—

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

 
—

 
1

 
1

Purchases
 
—

 
(2
)
 
(2
)
Sales
 
(1
)
 
—

 
(1
)
Settlements
 
—

 
1

 
1

Ending balance at December 31, 2014
$
(1
)
$
—

$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014
$
—

$
2

$
2

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
19

$
(108
)
$
(89
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 
(14
)
 
(39
)
 
(53
)
Purchases
 
34

 
—

 
34

Sales
 
(1
)
 
—

 
(1
)
Settlements
 
(29
)
 
5

 
(24
)
Ending balance at December 31, 2014
$
9

$
(142
)
$
(133
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014
$
—

$
(43
)
 $
(43
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
(6
)
$
(a)

$
(6
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 
(1
)
 
(a)

 
(1
)
Settlements
 
5

 
(a)

 
5

Ending balance at December 31, 2014
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014
$
(1
)
$
(a)

$
(1
)
(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 for the year ended December 31, 2013:
  
 
Net Derivative Commodity Contracts
  
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
5

$
(a)

$
5

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
)
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
)
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
)
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.
Schedule Of Carrying Amounts And Estimated Fair Values Of Long-Term Debt And Preferred Stock 
following table presents the carrying amounts and estimated fair values of our long-term debt and preferred stock at December 31, 2014 and 2013:
  
2014
 
2013
  
Carrying Amount
 
Fair Value
 
Carrying Amount
 
Fair Value
Ameren:(a)
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
6,240

 
$
7,135

 
$
6,038

 
$
6,584

Preferred stock
142

 
122

 
142

 
118

Ameren Missouri:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
3,999

 
$
4,518

 
$
3,757

 
$
4,124

Preferred stock
80

 
73

 
80

 
71

Ameren Illinois:
 
 
 
 
 
 
 
Long-term debt (including current portion)
$
2,241

 
$
2,517

 
$
1,856

 
$
2,028

Preferred stock
62

 
49

 
62

 
47

(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, 2014 and 2013:
Security Type
Cost
 
Gross Unrealized Gain
 
Gross Unrealized Loss
 
Fair Value
2014
 
 
 
 
 
 
 
Debt securities
$
175

 
$
7

$
(a)

 
$
182

Equity securities
138

 
230

 
4

 
364

Cash
1

 
—

 
—

 
1

Other(b)
2

 
—

 
—

 
2

Total
$
316

 
$
237

$
4

 
$
549

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

(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, 2014:
  
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
$
28

$
(a)

 
 
$
8

$
(a)

 
$
36

$
(a)

Equity securities
6

 
1

 
 
5

 
3

 
11

 
4

Total
$
34

$
1

 
 
$
13

$
3

 
$
47

$
4

(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, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Proceeds from sales and maturities
$
391

 
$
196

 
$
384

Gross realized gains
7

 
7

 
6

Gross realized losses
2

 
5

 
2

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, 2014:
 
Cost
 
Fair Value
Less than 5 years
$
98

 
$
99

5 years to 10 years
41

 
42

Due after 10 years
36

 
41

Total
$
175

 
$
182

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, 2014 and 2013:
 
2014

2013

Ameren(a)
$
710

$
461

Ameren Missouri
277

191

Ameren Illinois
278

159

(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 Ameren's pension and postretirement benefit plans as of December 31, 2014 and 2013. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 2014 and 2013, that have not been recognized in net periodic benefit costs.
  
2014
 
2013
  
Pension Benefits(a)
 
Postretirement
Benefits(a)
 
Pension Benefits(a)
 
Postretirement
Benefits(a)
Accumulated benefit obligation at end of year
$
4,176

$
(b)

 
$
3,698

$
(b)

Change in benefit obligation:
 
 
 
 
 
 
 
Net benefit obligation at beginning of year
$
3,900

$
1,096

 
$
4,051

$
1,157

Service cost
79

 
19

 
91

 
22

Interest cost
183

 
50

 
163

 
46

Participant contributions
—

 
16

 
—

 
16

Actuarial (gain) loss
462

 
84

 
(207
)
 
(76
)
Curtailment gain(c)
—

 
—

 
—

 
(3
)
Settlement(d)
—

 
—

 
—

 
(5
)
Benefits paid
(214
)
 
(65
)
 
(198
)
 
(64
)
Federal subsidy on benefits paid
(b)

 
3

 
(b)

 
3

Net benefit obligation at end of year
4,410

 
1,203

 
3,900

 
1,096

Change in plan assets:
 
 
 
 
 
 
 
Fair value of plan assets at beginning of year
3,461

 
1,074

 
3,127

 
938

Actual return on plan assets
448

 
75

 
376

 
156

Employer contributions
99

 
6

 
156

 
25

Federal subsidy on benefits paid
(b)

 
3

 
(b)

 
3

Participant contributions
—

 
16

 
—

 
16

Benefits paid
(214
)
 
(65
)
 
(198
)
 
(64
)
Fair value of plan assets at end of year
3,794

 
1,109

 
3,461

 
1,074

Funded status – deficiency
616

 
94

 
439

 
22

Accrued benefit cost at December 31
$
616

$
94

 
$
439

$
22

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

$
—

 
$
—

$
(9
)
Current liability(f)
3

 
2

 
3

 
1

Noncurrent liability
613

 
92

 
436

 
30

Net liability recognized
$
616

$
94

 
$
439

$
22

Amounts recognized in regulatory assets consist of:
 
 
 
 
 
 
 
Net actuarial (gain) loss
$
452

$
(7
)
 
$
282

$
(71
)
Prior service cost (credit)
(6
)
 
(16
)
 
(7
)
 
(20
)
Amounts (pretax) recognized in accumulated OCI consist of:
 
 
 
 
 
 
 
Net actuarial (gain) loss
29

 
(5
)
 
17

 
(12
)
Prior service cost (credit)
—

 
(1
)
 
—

 
(1
)
Total
$
475

$
(29
)
 
$
292

$
(104
)
(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, 2014 and 2013:
  
Pension Benefits
 
Postretirement Benefits
  
2014
 
2013
 
2014
 
2013
Discount rate at measurement date
4.00
%
 
4.75
%
 
4.00
%
 
4.75
%
Increase in future compensation
3.50

 
3.50

 
3.50

 
3.50

Medical cost trend rate (initial)
(a)

 
(a)

 
5.00

 
5.00

Medical cost trend rate (ultimate)
(a)

 
(a)

 
5.00

 
5.00

Years to ultimate rate
(a)

 
(a)

 
—

 
—

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 2014, 2013, and 2012:
  
Pension Benefits
 
Postretirement Benefits
  
2014
 
2013
 
2012
 
2014
 
2013
 
2012
Ameren Missouri
$
41

 
$
60

 
$
52

 
$
3

 
$
10

 
$
9

Ameren Illinois
39

 
50

 
46

 
2

 
11

 
35

Other
19

 
46

 
30

 
1

 
4

 
1

Ameren(a)
99

 
156

 
128

 
6

 
25

 
45

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Target Allocation Of The Plans' Asset Categories 
The following table presents our target allocations for 2015 and our pension and postretirement plans’ asset categories as of December 31, 2014 and 2013:
Asset
Category
Target Allocation
2015
 
Percentage of Plan Assets at December  31,
2014
 
2013
Pension Plan:
 
 
 
 
 
Cash and cash equivalents
0% - 5%
 
2
%
 
2
%
Equity securities:
 
 
 
 
 
U.S. large-capitalization
29% - 39%
 
34
%
 
36
%
U.S. small- and mid-capitalization
2% - 12%
 
7
%
 
8
%
International and emerging markets
9% - 19%
 
12
%
 
14
%
Total equity
50% - 60%
 
53
%
 
58
%
Debt securities
35% - 45%
 
41
%
 
36
%
Real estate
0% -   9%  
 
4
%
 
4
%
Private equity
0% -   4%  
 
(a)

 
(a)

Total
 
 
100
%
 
100
%
Postretirement Plans:
 
 
 
 
 
Cash and cash equivalents
0% - 10%
 
4
%
 
4
%
Equity securities:
 
 
 
 
 
U.S. large-capitalization
33% - 43%
 
40
%
 
41
%
U.S. small- and mid-capitalization
3% - 13%
 
7
%
 
8
%
International
10% - 20%
 
13
%
 
14
%
Total equity
55% - 65%
 
60
%
 
63
%
Debt securities
30% - 40%
 
36
%
 
33
%
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, 2014 and 2013:
 
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,
2014:
 
 
 
 
 
 
 
 
 
 
 
Real estate
$
131

 
$
11

 
$
—

 
$
5

 
$
—

 
$
147

Private equity
15

 
(9
)
 
10

 
(3
)
 
—

 
13

2013:
 
 
 
 
 
 
 
 
 
 
 
Real estate
$
118

 
$
9

 
$
—

 
$
4

 
$
—

 
$
131

Private equity
19

 
(9
)
 
11

 
(6
)
 
—

 
15

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 2014, 2013, and 2012:
 
Pension Benefits
Ameren(a)
 
Postretirement Benefits
Ameren(a)
2014
 
 
 
Service cost
$
79

 
$
19

Interest cost
183

 
50

Expected return on plan assets
(229
)
 
(65
)
Amortization of:
 
 
 
Prior service credit
(1
)
 
(5
)
Actuarial (gain) loss
49

 
(7
)
Net periodic benefit cost (benefit)
$
81

 
$
(8
)
2013
 
 
 
Service cost
$
91

 
$
22

Interest cost
163

 
46

Expected return on plan assets
(218
)
 
(62
)
Amortization of:
 
 
 
Prior service credit
(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 credit
(3
)
 
(6
)
Actuarial loss
75

 
5

Net periodic benefit cost(c)
$
111

 
$
14

(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 2015 are as follows:
  
Pension Benefits
Ameren(a)
 
Postretirement Benefits
Ameren(a)
Regulatory assets:
 
 
 
Prior service credit
$
(1
)
 
$
(4
)
Net actuarial loss
86

 
15

Accumulated OCI:
 
 
 
Net actuarial (gain) loss
2

 
(2
)
Total
$
87

 
$
9

(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, 2014, 2013, and 2012:
  
Pension Costs
 
Postretirement Costs
  
2014
 
2013
 
2012
 
2014
 
2013
 
2012
Ameren Missouri
$
50

 
$
69

 
$
63

 
$
3

 
$
8

 
$
10

Ameren Illinois
30

 
41

 
37

 
(9
)
 
—

 
4

Other
1

 
5

 
2

 
(2
)
 
—

 
—

Ameren(a)
81

 
115

 
102

 
(8
)
 
8

 
14

(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, which reflect expected future service, as of December 31, 2014, are as follows:
  
Pension Benefits
 
Postretirement Benefits
  
Paid from
Qualified
Trust
 
        Paid from
         Company
      Funds
 
        Paid from
         Qualified
      Trust
 
        Paid from
         Company
      Funds
2015
$
253

 
$
3

 
$
58

 
$
2

2016
256

 
3

 
61

 
2

2017
257

 
4

 
64

 
2

2018
260

 
3

 
68

 
2

2019
260

 
3

 
70

 
2

2020 - 2024
1,273

 
11

 
388

 
11

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, 2014, 2013, and 2012:
  
Pension Benefits
 
Postretirement Benefits
  
2014
 
2013
 
2012
 
2014
 
2013
 
2012
Discount rate at measurement date
4.75
%
 
4.00
%
 
4.50
%
 
4.75
%
 
4.00
%
 
4.50
%
Expected return on plan assets
7.25

 
7.50

 
7.75

 
7.00

 
7.25

 
7.50

Increase in future compensation
3.50

 
3.50

 
3.50

 
3.50

 
3.50

 
3.50

Medical cost trend rate (initial)
(a)

 
(a)

 
(a)

 
5.00

 
5.00

 
5.50

Medical cost trend rate (ultimate)
(a)

 
(a)

 
(a)

 
5.00

 
5.00

 
5.00

Years to ultimate rate
(a)

 
(a)

 
(a)

 
—

 
—

 
1 year

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
$
(1
)
 
$
138

 
$
1

 
$
39

0.25% increase in salary scale
2

 
13

 
—

 
—

1.00% increase in annual medical trend
—

 
—

 
3

 
36

1.00% decrease in annual medical trend
—

 
—

 
(2
)
 
(33
)
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, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Ameren Missouri
$
16

 
$
16

 
$
16

Ameren Illinois
11

 
10

 
9

Other
1

 
1

 
1

Ameren(a)
28

 
27

 
26

(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, 2014:
 
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
$
—

 
$
38

 
$
—

 
$
38

Equity securities:
 
 
 
 
 
 
 
U.S. large-capitalization
—

 
1,331

 
—

 
1,331

U.S. small- and mid-capitalization
270

 
—

 
—

 
270

International and emerging markets
134

 
360

 
—

 
494

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
1,026

 
—

 
1,026

Municipal bonds
—

 
175

 
—

 
175

U.S. treasury and agency securities
6

 
366

 
—

 
372

Other
—

 
31

 
—

 
31

Real estate
—

 
—

 
147

 
147

Private equity
—

 
—

 
13

 
13

Derivative assets
1

 
—

 
—

 
1

Total
$
411

 
$
3,327

 
$
160

 
$
3,898

Less: Medical benefit assets at December 31(a)
 
 
 
 
 
 
(125
)
Plus: Net receivables at December 31(b)
 
 
 
 
 
 
21

Fair value of pension plans assets at year end
 
 
 
 
 
 
$
3,794

(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, 2013:
 
Quoted Prices in
Active Markets for
Identified Assets or Liabilities
(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.
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, 2014:
 
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
$
89

 
$
—

 
$
—

 
$
89

Equity securities:
 
 
 
 
 
 
 
U.S. large-capitalization
291

 
101

 
—

 
392

U.S. small- and mid-capitalization
70

 
—

 
—

 
70

International
37

 
94

 
—

 
131

Other
—

 
7

 
 
 
7

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
105

 
—

 
105

Municipal bonds
—

 
111

 
—

 
111

U.S. treasury and agency securities
—

 
89

 
—

 
89

Other
—

 
44

 
—

 
44

Total
$
487

 
$
551

 
$
—

 
$
1,038

Plus: Medical benefit assets at December 31(a)
 
 
 
 
 
 
125

Less: Net payables at December 31(b)
 
 
 
 
 
 
(54
)
Fair value of postretirement benefit plans assets at year end
 
 
 
 
 
 
$
1,109

(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 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, 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

Other
—

 
2

 
—

 
2

Debt securities:
 
 
 
 
 
 
 
Corporate bonds
—

 
97

 
—

 
97

Municipal bonds
—

 
103

 
—

 
103

U.S. treasury and agency securities
—

 
72

 
—

 
72

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.
Stock-Based Compensation (Tables)
Summary Of Nonvested Shares Related To Long-Term Incentive Plan
A summary of nonvested shares at December 31, 2014, and changes during the year ended December 31, 2014, under the 2006 Incentive Plan and the 2014 Incentive Plan are presented below:
  
Performance Share Units
  
Share
Units
 
Weighted-average
Fair Value per Share Unit
Nonvested at January 1, 2014
1,218,544

 
$
33.23

Granted(a)
688,323

 
38.90

April Grants(b)
38,559

 
50.34

Unearned or forfeited(c)
(97,432
)
 
34.42

Earned and vested(d)
(685,617
)
 
36.12

Nonvested at December 31, 2014
1,162,377

 
$
35.35

(a)
Includes performance share units (share units) granted to certain executive and nonexecutive officers and other eligible employees in 2014 under the 2006 Incentive Plan and the 2014 Incentive Plan.
(b)
In April 2014, certain executive officers were granted additional share units under the 2006 Incentive Plan and the 2014 Incentive Plan. The significant assumptions used to calculate fair value included a prorated three-year risk-free rate ranging from 0.76% to 0.79%, volatility of 12% to 18% for the peer group, and Ameren’s attainment of a three-year average earnings per share threshold during the performance period.
(c)
Includes share units granted in 2012 that were not earned based on performance provisions of the award grants.
(d)
Includes share units granted in 2012 that vested as of December 31, 2014, that were earned pursuant to the provisions of the award grants.
Income Taxes (Tables)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
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 for the difference between the effective income tax rate and the statutory federal income tax rate for the years ended December 31, 2014, 2013, and 2012:
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2014
 
 
 
 
 
Statutory federal income tax rate:
35
 %
 
35
 %
 
35
 %
Increases (decreases) from:
 
 
 
 
 
Amortization of investment tax credit
(1
)
 
—

 
(1
)
State tax
3

 
6

 
4

Other permanent items
—

 
—

 
1

Effective income tax rate
37
 %
 
41
 %
 
39
 %
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
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
—

 
—

 
(1
)
Effective income tax rate
37
 %
 
40
 %
 
37
 %


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, 2014, 2013, and 2012:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
2014
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
(13
)
 
$
(51
)
 
$
27

 
$
(37
)
State
(3
)
 
(2
)
 
(32
)
 
(37
)
Deferred taxes:
 
 
 
 
 
 
 
Federal
222

 
159

 
(12
)
 
369

State
28

 
38

 
22

 
88

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

 
(6
)
Total income tax expense
$
229

 
$
143

 
$
5

 
$
377

2013
 
 
 
 
 
 
 
Current taxes:
 
 
 
 
 
 
 
Federal
$
136

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

 
21

 
(43
)
(a) 
19

Deferred taxes:
 
 
 
 
 
 
 
Federal
64

 
99

 
205

(a) 
368

State
6

 
6

 
36

(a) 
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


(a)
These amounts are substantially related to the reversal of unrecognized tax benefits as a result of 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. The amounts 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, 2014 and 2013:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
2014
 
 
 
 
 
 
 
Accumulated deferred income taxes, net liability (asset):
 
 
 
 
 
 
 
Plant related
$
2,776

 
$
1,393

 
$
16

 
$
4,185

Regulatory assets, net
82

 
(5
)
 
1

 
78

Deferred employee benefit costs
(80
)
 
(45
)
 
(95
)
 
(220
)
Revenue requirement reconciliation adjustments

—

 
66

 
3

 
69

Tax carryforwards
(107
)
 
(139
)
 
(429
)
 
(675
)
Other
86

 
(22
)
 
70

 
134

Total net accumulated deferred income tax liabilities (assets)(a)
$
2,757

 
$
1,248

 
$
(434
)
 
$
3,571

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
)
Revenue requirement reconciliation adjustments
—

 
(4
)
 
2

 
(2
)
Tax carryforwards
(76
)
 
(95
)
 
(370
)
 
(541
)
Other
67

 
10

 
38

 
115

Total net accumulated deferred income tax liabilities (assets)(b)
$
2,504

 
$
1,071

 
$
(431
)
 
$
3,144


(a)
Includes $49 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2014.
(b)
Includes $20 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2013.
Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards 
2013.
The following table presents the components of deferred tax assets relating to net operating loss carryforwards, tax credit carryforwards, and charitable contribution carryforwards at December 31, 2014:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
Net operating loss carryforwards:
 
 
 
 
 
 
 
Federal(a)
$
75

 
$
127

 
$
255

 
$
457

State(b)
11

 
10

 
53

 
74

Total net operating loss carryforwards
$
86

 
$
137

 
$
308

 
$
531

Tax credit carryforwards:
 
 
 
 
 
 
 
Federal(c)
$
21

 
$
1

 
$
77

 
$
99

State(d)
1

 
2

 
33

 
36

State valuation allowance(e)
(1
)
 
(1
)
 
(2
)
 
(4
)
Total tax credit carryforwards
$
21

 
$
2

 
$
108

 
$
131

Charitable contribution carryforwards(f)
$
—

 
$
—

 
$
19

 
$
19

Valuation allowance(g)
—

 
—

 
(6
)
 
(6
)
Total charitable contribution carryforwards
$
—

 
$
—

 
$
13

 
$
13


(a)
Will begin to expire in 2028.
(b)
Will begin to expire in 2020.
(c)
Will begin to expire in 2029.
(d)
Began to expire in 2013.
(e)
This balance increased by less than $1 million, $- million, and $- million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, during 2014.
(f)
These began to expire in 2013.
(g)
This balance increased by $3 million, $- million and $- million for Ameren, Ameren Missouri and Ameren Illinois, respectively, during 2014.
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, tax credit carryforwards, and charitable contribution carryforwards at December 31, 2013:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
Net operating loss carryforwards:
 
 
 
 
 
 
 
Federal(a)
$
61

 
$
84

 
$
215

 
$
360

State(b)
3

 
11

 
34

 
48

Total net operating loss carryforwards
$
64

 
$
95

 
$
249

 
$
408

Tax credit carryforwards:
 
 
 
 
 
 
 
Federal(c)
$
12

 
$
—

 
$
76

 
$
88

State(d)
1

 
1

 
32

 
34

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

 
$
—

 
$
106

 
$
118

Charitable contribution carryforwards(f)
$
—

 
$
—

 
$
18

 
$
18

Valuation allowance(g)
—

 
—

 
(3
)
 
(3
)
Total charitable contribution carryforwards
$
—

 
$
—

 
$
15

 
$
15


(a)
Will begin to expire in 2028
(b)
Will begin to expire in 2019.
(c)
Will begin to expire in 2029.
(d)
Began to expire in 2013.
(e)
Balance increased by $2 million, $- million, and $- million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, during 2013.
(f)
These began to expire in 2013.
(g)
This balance increased by $3 million, $- million, and $- million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, during 2013.
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, 2012, 2013, and 2014, is as follows:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
Unrecognized tax benefits – January 1, 2012
$
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 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 (decreases) based on tax positions related to 2013
16

 
—

 
53

(a) 
69

Changes related to settlements with taxing authorities
—

 
—

 
—

 
—

Decreases related to the lapse of statute of limitations
1

 
—

 
—

 
1

Unrecognized tax benefits – December 31, 2013
$
31

 
$
(1
)
 
$
60

 
$
90

Increases based on tax positions prior to 2014
1

 
1

 
4

 
6

Decreases based on tax positions prior to 2014
(32
)
 
(1
)
 
(9
)
 
(42
)
Increases based on tax positions related to 2014
—

 
—

 
—

 
—

Changes related to settlements with taxing authorities
—

 
—

 
—

 
—

Increases related to the lapse of statute of limitations
—

 
—

 
—

 
—

Unrecognized tax benefits (detriments) – December 31, 2014
$
—

 
$
(1
)
 
$
55

 
$
54

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

 
$
(1
)
 
$
(1
)
 
$
1

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

 
$
—

 
$
51

(a) 
$
54

Total unrecognized tax benefits that, if recognized, would affect the effective tax rates as of December 31, 2014
$
—

 
$
(1
)
 
$
53

(a) 
$
52


(a)
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.
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, 2012, 2013, and 2014, is as follows:
 
Ameren Missouri
 
Ameren Illinois
 
Other
 
Ameren
Liability for interest – January 1, 2012
$
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

Interest charges (income) for 2014
—

 
—

 
(1
)
 
(1
)
Liability for interest – December 31, 2014
$
—

 
$
—

 
$
—

 
$
—

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, 2014, 2013, and 2012. 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
 
2014
$
5

$
(a)

with Ameren Illinois
 
 
2013
 
3

 
(a)

 
 
 
2012
 
(b)

 
(a)

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2014
 
21

 
2

rent and facility services
 
 
2013
 
21

 
1

 
 
 
2012
 
19

 
1

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2014
 
1

 
(b)

miscellaneous support services
 
 
2013
 
1

 
3

 
 
 
2012
 
1

 
(b)

Total Operating Revenues
 
 
2014
$
27

$
2

 
 
 
2013
 
25

 
4

 
 
 
2012
 
20

 
1

Ameren Illinois power supply
Purchased Power
 
2014
$
(a)

$
5

agreements with Ameren Missouri
 
 
2013
 
(a)

 
3

 
 
 
2012
 
(a)

 
(b)

Ameren Illinois transmission
Purchased Power
 
2014
 
(a)

 
2

services with ATXI
 
 
2013
 
(a)

 
2

 
 
 
2012
 
(a)

 
3

Total Purchased Power
 
 
2014
$
(a)

$
7

 
 
 
2013
 
(a)

 
5

 
 
 
2012
 
(a)

 
3

Ameren Services support services
Other Operations and
 
2014
$
124

$
109

agreement
Maintenance
 
2013
 
116

 
93

 
 
 
2012
 
106

 
88

Insurance premiums(c)
Other Operations and
 
2014
 
(b)

 
(a)

 
Maintenance
 
2013
 
(b)

 
(a)

 
 
 
2012
 
(b)

 
(a)

Total Other Operations and
 
 
2014
$
124

$
109

Maintenance Expenses
 
 
2013
 
116

 
93

 
 
 
2012
 
106

 
88

Money pool borrowings (advances)
Interest (Charges)
 
2014
$
(b)

$
(b)

 
Income
 
2013
 
(b)

 
(b)

 
 
 
2012
 
(b)

 
(b)

(a)
Not applicable.
(b)
Amount less than $1 million.
(c)
Represents insurance premiums paid to Missouri Energy Risk Assurance Company LLC, an affiliate, for replacement power.

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, 2014. 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 LLC
$
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)
NEIL provides $2.25 billion in property damage, decontamination, and premature decommissioning insurance.
(e)
All NEIL-insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL.
(f)
European Mutual Association for Nuclear Insurance provides $500 million in excess of the $2.25 billion property coverage provided by NEIL.
(g)
Provides replacement power cost insurance in the event of a prolonged accidental outage. Weekly indemnity is 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. Nonradiation events are sub-limited to $328 million.
(h)
Provides replacement power cost insurance in the event of a prolonged accidental outage. The coverage commences after the first 52 weeks of insurance coverage from NEIL concludes; it is a weekly indemnity of up to $0.9 million for 71 weeks in excess of the $3.6 million per week set forth above. Missouri Energy Risk Assurance Company LLC is an affiliate; it 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, 2014:
 
2015
 
2016
 
2017
 
2018
 
2019
 
After 5 Years
 
Total
Ameren:(a)
 
 
 
 
 
 
 
 
 
 
 
 
 
Minimum capital lease payments(b)
$
33

 
$
33

 
$
33

 
$
32

 
$
32

 
$
360

 
$
523

Less amount representing interest
27

 
27

 
27

 
26

 
25

 
97

 
229

Present value of minimum capital lease payments
$
6

 
$
6

 
$
6

 
$
6

 
$
7

 
$
263

 
$
294

Operating leases(c)
13

 
12

 
12

 
12

 
11

 
38

 
98

Total lease obligations
$
19

 
$
18

 
$
18

 
$
18

 
$
18

 
$
301

 
$
392

Ameren Missouri:
 
 
 
 
 
 
 
 
 
 
 
 
 
Minimum capital lease payments(b)
$
33

 
$
33

 
$
33

 
$
32

 
$
32

 
$
360

 
$
523

Less amount representing interest
27

 
27

 
27

 
26

 
25

 
97

 
229

Present value of minimum capital lease payments
$
6

 
$
6

 
$
6

 
$
6

 
$
7

 
$
263

 
$
294

Operating leases(c)
11

 
11

 
11

 
10

 
10

 
37

 
90

Total lease obligations
$
17

 
$
17

 
$
17

 
$
16

 
$
17

 
$
300

 
$
384

Ameren Illinois:
 
 
 
 
 
 
 
 
 
 
 
 
 
Operating leases(c)
$
1

 
$
1

 
$
1

 
$
1

 
$
1

 
$
1

 
$
6

(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 obligations of $2 million, $1 million, and $1 million for Ameren, Ameren Missouri, and Ameren Illinois for these items are included in the 2015 through 2019 columns, respectively.
Schedule Of Rental Expense 
The following table presents total rental expense, included in operating expenses, for the years ended December 31, 2014, 2013, and 2012:
 
2014
 
2013
 
2012
Ameren(a)
$
37

 
$
32

 
$
33

Ameren Missouri
32

 
29

 
29

Ameren Illinois
25

 
21

 
19

(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
Schedule Of Estimated Purchased Commitments 
December 31, 2014. Ameren’s and Ameren Missouri’s purchased power commitments include a 102-megawatt power purchase agreement with a wind farm operator, which expires in 2024. Ameren’s and Ameren Illinois’ purchased power commitments 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, 2014. In addition, the Other column includes Ameren's and Ameren Missouri's obligations related to customer energy efficiency programs under the MEEIA as approved by the MoPSC's December 2012 electric rate order. Ameren Missouri expects to incur costs of $71 million in 2015 for these customer energy efficiency programs. See Note 2 – Rate and Regulatory Matters for additional information about the MEEIA.
 
Coal
 
Natural
Gas(a)
 
Nuclear
Fuel
 
Purchased
Power(b)
 
Methane
Gas
 
Other
 
Total
Ameren:(c)
 
 
 
 
 
 
 
 
 
 
 
 
 
2015
$
654

 
$
222

 
$
53

 
$
190

 
$
3

 
$
195

 
$
1,317

2016
659

 
125

 
60

 
104

 
3

 
78

 
1,029

2017
682

 
85

 
59

 
66

 
4

 
53

 
949

2018
111

 
53

 
82

 
55

 
5

 
51

 
357

2019
114

 
32

 
42

 
56

 
5

 
54

 
303

Thereafter
—

 
71

 
138

 
596

 
76

 
350

 
1,231

Total
$
2,220

 
$
588

 
$
434

 
$
1,067

 
$
96

 
$
781

 
$
5,186

Ameren Missouri:
 
 
 
 
 
 
 
 
 
 
 
 
 
2015
$
654

 
$
39

 
$
53

 
$
21

 
$
3

 
$
128

 
$
898

2016
659

 
22

 
60

 
21

 
3

 
39

 
804

2017
682

 
17

 
59

 
21

 
4

 
26

 
809

2018
111

 
11

 
82

 
21

 
5

 
27

 
257

2019
114

 
10

 
42

 
21

 
5

 
27

 
219

Thereafter
—

 
22

 
138

 
106

 
76

 
183

 
525

Total
$
2,220

 
$
121

 
$
434

 
$
211

 
$
96

 
$
430

 
$
3,512

Ameren Illinois:
 
 
 
 
 
 
 
 
 
 
 
 
 
2015
$
—

 
$
183

 
$
—

 
$
169

 
$
—

 
$
29

 
$
381

2016
—

 
103

 
—

 
83

 
—

 
24

 
210

2017
—

 
68

 
—

 
45

 
—

 
24

 
137

2018
—

 
42

 
—

 
34

 
—

 
24

 
100

2019
—

 
22

 
—

 
35

 
—

 
27

 
84

Thereafter
—

 
49

 
—

 
490

 
—

 
167

 
706

Total
$
—

 
$
467

 
$
—

 
$
856

 
$
—

 
$
295

 
$
1,618

(a)
Includes amounts for generation and for distribution.
(b)
The purchased power amounts for Ameren and Ameren Illinois include agreements through 2032 for renewable energy credits 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.
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, 2014:
Ameren
 
Ameren
Missouri
 
Ameren
Illinois
 
Total(a)
1
 
45
 
57
 
70

(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, 2014, 2013, and 2012:
 
Year ended
 
 
2014
 
2013
 
2012
 
Operating revenues
$
1

 
$
1,037

 
$
1,047

 
Operating expenses
(2
)

(1,207
)
(a) 
(3,474
)
(b) 
Operating income (loss)
(1
)
 
(170
)
 
(2,427
)
 
Other income (loss)
—

 
(1
)
 
—

 
Interest charges
—

 
(39
)
 
(56
)
 
Income (loss) before income taxes
(1
)
 
(210
)
 
(2,483
)
 
Income tax (expense) benefit
—

 
(13
)
 
987

 
Income (loss) from discontinued operations, net of taxes
$
(1
)
 
$
(223
)
 
$
(1,496
)
 
(a)
Includes a $201 million pretax loss on disposal relating to the New AER divestiture.
(b)
Includes a noncash pretax asset impairment charge of $2.58 billion to reduce the carrying value of AER's energy centers to their estimated fair value under held and used accounting guidance.
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, 2014 and 2013:
 
December 31, 2014
 
December 31, 2013
Assets of discontinued operations
 
 
 
Accounts receivable and unbilled revenue
$
—

 
$
5

Materials and supplies
—

 
5

Property and plant, net
—

 
142

Accumulated deferred income taxes, net(a)
15

 
13

Total assets of discontinued operations
$
15

 
$
165

Liabilities of discontinued operations
 
 
 
Accounts payable and other current obligations
$
1

 
$
5

Asset retirement obligations(b)
32

 
40

Total liabilities of discontinued operations
$
33

 
$
45

(a)
The December 31, 2014 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 $32 million and $31 million at December 31, 2014 and 2013, respectively.
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 and capital expenditures from continuing operations for the years ended December 31, 2014, 2013, and 2012, and total assets in continuing operations as of December 31, 2014, 2013, and 2012:
 
Ameren
Missouri
 
Ameren
Illinois
 
Other
 
Intersegment
Eliminations
 
Consolidated
 
2014
 
 
 
 
 
 
 
 
 
 
External revenues
$
3,526

 
$
2,496

 
$
31

 
$
—

 
$
6,053

 
Intersegment revenues
27

 
2

 
2

 
(31
)
 
—

 
Depreciation and amortization
473

 
263

 
9

 
—

 
745

 
Interest and dividend income
28

 
7

 
2

 
—

 
37

 
Interest charges
211

 
112

 
18

 
—

 
341

 
Income taxes
229

 
143

 
5

 
—

 
377

 
Net income (loss) attributable to Ameren Corporation from continuing operations
390

 
201

 
(4
)
 
—

 
587

 
Capital expenditures
747

 
835

 
203

(a) 
—

 
1,785

 
Total assets
13,541

 
8,381

 
942

 
(203
)
 
22,661

(b) 
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) 
.
(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
2014
 
 
2013
Quarter ended (a)
March 31
 
June 30
 
September 30
 
December 31
 
 
March 31
 
June 30
 
September 30
 
December 31
Operating revenues
$
1,594

 
$
1,419

 
$
1,670

 
$
1,370

 
 
$
1,475

 
$
1,403

 
$
1,638

 
$
1,322

Operating income
246

 
322

 
561

 
125

 
 
185

 
261

 
567

 
171

Net income (loss)
98

 
150

 
295

 
49

 
 
(143
)
 
96

 
304

 
38

Net income attributable to Ameren Corporation – continuing operations
$
97

 
$
150

 
$
294

 
$
46

 
 
$
54

 
$
105

 
$
305

 
$
48

Net income (loss) attributable to Ameren Corporation – discontinued operations
(1
)
 
(1
)
 
(1
)
 
2

 
 
(199
)
 
(10
)
 
(3
)
 
(11
)
Net income (loss) attributable to Ameren Corporation
$
96

 
$
149

 
$
293

 
$
48

 
 
$
(145
)
 
$
95

 
$
302

 
$
37

Earnings per common share – basic – continuing operations
$
0.40

 
$
0.62

 
$
1.21

 
$
0.19

 
 
$
0.22

 
$
0.44

 
$
1.26

 
$
0.19

Earnings (loss) per common share – basic – discontinued operations
—

 
(0.01
)
 
—

 
0.01

 
 
(0.82
)
 
(0.05
)
 
(0.01
)
 
(0.04
)
Earnings (loss) per common share – basic
$
0.40

 
$
0.61

 
$
1.21

 
$
0.20

 
 
$
(0.60
)
 
$
0.39

 
$
1.25

 
$
0.15

Earnings per common share – diluted – continuing operations
$
0.40

 
$
0.62

 
$
1.20

 
$
0.19

 
 
$
0.22

 
$
0.44

 
$
1.25

 
$
0.19

Earnings (loss) per common share – diluted – discontinued operations
—

 
(0.01
)
 
—

 
0.01

 
 
(0.82
)
 
(0.05
)
 
(0.01
)
 
(0.04
)
Earnings (loss) per common share – diluted
$
0.40

 
$
0.61

 
$
1.20

 
$
0.20

 
 
$
(0.60
)
 
$
0.39

 
$
1.24

 
$
0.15

(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.

Ameren Missouri Quarter ended
 
Operating
Revenues
 
Operating
Income
 
Net Income
 (Loss)
 
Net Income (Loss)
Available
to Common
Stockholder
March 31, 2014
 
$
817

 
$
119

 
$
48

 
$
47

March 31, 2013
 
796

 
111

 
41

 
40

June 30, 2014
 
900

 
243

 
127

 
126

June 30, 2013
 
889

 
179

 
85

 
84

September 30, 2014
 
1,097

 
394

 
223

 
222

September 30, 2013
 
1,093

 
417

 
239

 
238

December 31, 2014
 
739

 
29

 
(5
)
 
(5
)
December 31, 2013
 
763

 
96

 
33

 
33


Ameren Illinois Quarter ended
 
Operating
Revenues
 
Operating
Income
 
Net Income
 
Net Income
Available
to Common
Stockholder
March 31, 2014
 
$
774

 
$
120

 
$
54

 
$
53

March 31, 2013
 
684

 
85

 
32

 
31

June 30, 2014
 
519

 
75

 
29

 
28

June 30, 2013
 
516

 
87

 
32

 
31

September 30, 2014
 
572

 
158

 
75

 
75

September 30, 2013
 
547

 
158

 
77

 
77

December 31, 2014
 
633

 
97

 
46

 
45

December 31, 2013
 
564

 
85

 
22

 
21

Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Accounting Policies [Line Items]
 
 
 
 
Nuclear decommissioning trust fund
$ 549 
$ 494 
 
 
Average performance share units excluded from calculation
0 
0 
0 
 
Unrecognized Tax Benefit Recorded In Other Deferred Credits And Liabilities
52 
84 
 
 
Unrecognized Tax Benefits
54 
90 
156 
148 
Goodwill
411 
411 
 
 
Ameren Illinois Company
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
Capital contribution from parent
15 
 
 
 
Unrecognized Tax Benefit Recorded In Other Deferred Credits And Liabilities
0 
0 
 
 
Unrecognized Tax Benefits
(1)
(1)
13 
11 
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]
 
 
 
 
Capital contribution from parent
215 
4 
1 
 
Noncash Or Part Noncash Capital Contribution From Parent
9 
 
 
 
Nuclear decommissioning trust fund
549 
494 
 
 
Unrecognized Tax Benefit Recorded In Other Deferred Credits And Liabilities
0 
15 
 
 
Unrecognized Tax Benefits
0 
31 
136 
124 
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 
 
 
 
Return of capital to parent
$ (215)
 
 
 
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
813,000 
 
 
 
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% 
 
 
 
Summary Of Significant Accounting Policies (Schedule Of Material And Supplies) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Accounting Policies [Line Items]
 
 
Fuel
$ 134 1
$ 144 1
Gas stored underground
127 
127 
Other materials and supplies
263 
255 
Total materials and supplies
524 
526 
Union Electric Company
 
 
Accounting Policies [Line Items]
 
 
Fuel
134 1
144 1
Gas stored underground
16 
17 
Other materials and supplies
197 
191 
Total materials and supplies
347 
352 
Ameren Illinois Company
 
 
Accounting Policies [Line Items]
 
 
Gas stored underground
111 
110 
Other materials and supplies
66 
64 
Total materials and supplies
$ 177 
$ 174 
Summary Of Significant Accounting Policies (Schedule Of Rates Used For Allowance For Funds Used During Construction) (Details)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Union Electric Company
 
 
 
Accounting Policies [Line Items]
 
 
 
Allowance for funds used during construction, rate
7.00% 
8.00% 
8.00% 
Ameren Illinois Company
 
 
 
Accounting Policies [Line Items]
 
 
 
Allowance for funds used during construction, rate
2.00% 
8.00% 
9.00% 
Summary Of Significant Accounting Policies (Schedule Of Asset Retirement Obligations) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
 
 
Balance
$ 369,000,000 
$ 349,000,000 
Liabilities incurred
2,000,000 
 
Liabilities settled
(2,000,000)
(1,000,000)
Accretion in period
21,000,000 1
19,000,000 1
Change in estimates
6,000,000 2 3
2,000,000 3
Balance
396,000,000 
369,000,000 
Nuclear decommissioning trust fund
549,000,000 
494,000,000 
Union Electric Company
 
 
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
 
 
Balance
366,000,000 
346,000,000 
Liabilities incurred
2,000,000 
 
Liabilities settled
(2,000,000)
(1,000,000)
Accretion in period
21,000,000 1
19,000,000 1
Change in estimates
2,000,000 3
2,000,000 3
Balance
389,000,000 
366,000,000 
Nuclear decommissioning trust fund
549,000,000 
494,000,000 
Ameren Illinois Company
 
 
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
 
 
Balance
3,000,000 4
3,000,000 
Liabilities settled
(1,000,000)5
(1,000,000)5
Accretion in period
1,000,000 1 5
1,000,000 1 5
Change in estimates
4,000,000 1
1,000,000 5
Balance
$ 7,000,000 4
$ 3,000,000 4
Summary Of Significant Accounting Policies (Schedule Of Excise Taxes) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Accounting Policies [Line Items]
 
 
 
Excise tax expense
$ 215 
$ 213 
$ 193 
Union Electric Company
 
 
 
Accounting Policies [Line Items]
 
 
 
Excise tax expense
151 
152 
139 
Ameren Illinois Company
 
 
 
Accounting Policies [Line Items]
 
 
 
Excise tax expense
$ 64 
$ 61 
$ 54 
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, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Accounting Policies [Abstract]
 
 
 
 
 
 
 
 
 
 
 
Continuing Operations
$ 46 
$ 294 
$ 150 
$ 97 
$ 48 
$ 305 
$ 105 
$ 54 
$ 587 
$ 512 
$ 516 
Discontinued Operations
2 
(1)
(1)
(1)
(11)
(3)
(10)
(199)
(1)
(223)
(1,490)
Net income (loss) attributable to Ameren Corporation
$ 48 
$ 293 
$ 149 
$ 96 
$ 37 
$ 302 
$ 95 
$ (145)
$ 586 
$ 289 
$ (974)
Average Common Shares Outstanding - Basic
 
 
 
 
 
 
 
 
242.6 
242.6 
242.6 
Assumed Settlement of Performance Share Units
 
 
 
 
 
 
 
 
1.8 
1.9 
0.4 
Average Common Shares Outstanding - Diluted
 
 
 
 
 
 
 
 
244.4 
244.5 
243.0 
Continuing Operations - Basic
$ 0.19 
$ 1.21 
$ 0.62 
$ 0.40 
$ 0.19 
$ 1.26 
$ 0.44 
$ 0.22 
$ 2.42 
$ 2.11 
$ 2.13 
Discontinued Operations - Basic
$ 0.01 
 
$ (0.01)
$ 0.00 
$ (0.04)
$ (0.01)
$ (0.05)
$ (0.82)
$ 0.00 
$ (0.92)
$ (6.14)
Earnings (Loss) per Common Share – Basic
$ 0.20 
$ 1.21 
$ 0.61 
$ 0.40 
$ 0.15 
$ 1.25 
$ 0.39 
$ (0.60)
$ 2.42 
$ 1.19 
$ (4.01)
Continuing Operations - Diluted
$ 0.19 
$ 1.20 
$ 0.62 
$ 0.40 
$ 0.19 
$ 1.25 
$ 0.44 
$ 0.22 
$ 2.40 
$ 2.10 
$ 2.13 
Discontinued Operations - Diluted
$ 0.01 
$ 0.00 
$ (0.01)
$ 0.00 
$ (0.04)
$ (0.01)
$ (0.05)
$ (0.82)
$ 0.00 
$ (0.92)
$ (6.14)
Earnings (Loss) per Common Share – Diluted
$ 0.20 
$ 1.20 
$ 0.61 
$ 0.40 
$ 0.15 
$ 1.24 
$ 0.39 
$ (0.60)
$ 2.40 
$ 1.18 
$ (4.01)
Average performance share units excluded from calculation
 
 
 
 
 
 
 
 
0 
0 
0 
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Supplemental Cash Flow Information [Line Items]
 
 
 
Interest Paid, Capitalized
$ 18 
$ 37 
$ 30 
Interest Paid, Net
333 
393 
433 
Income Taxes Paid, Net
(27)
8 
1 
Continuing Operations
 
 
 
Supplemental Cash Flow Information [Line Items]
 
 
 
Interest Paid, Capitalized
18 
20 
17 
Interest Paid, Net
333 1
362 1
384 1
Income Taxes Paid, Net
(41)
116 
10 
Discontinued Operations
 
 
 
Supplemental Cash Flow Information [Line Items]
 
 
 
Interest Paid, Capitalized
0 
17 
13 
Interest Paid, Net
 
31 2
49 2
Income Taxes Paid, Net
$ 14 
$ (108)
$ (9)
Rate And Regulatory Matters Rate and Regulatory Matters (Narrative-Missouri) (Details) (USD $)
12 Months Ended 1 Months Ended 3 Months Ended 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2014
Union Electric Company
Dec. 31, 2013
Union Electric Company
Dec. 31, 2012
Union Electric Company
Jul. 31, 2014
Electric Distribution
Pending Rate Case [Member]
Union Electric Company
Dec. 31, 2014
Electric Distribution
Accounting Authority Order Request
Union Electric Company
Dec. 31, 2014
MEEIA
Electric Distribution
Union Electric Company
Dec. 31, 2014
MOPSC [Member]
Electric Distribution
Pending Rate Case [Member]
Union Electric Company
Dec. 31, 2014
Fac Prudence Review
Subsequent Periods After September 30, 2009
Union Electric Company
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Public Utilities, Requested Rate Increase (Decrease), Amount
 
 
 
 
 
 
$ 190,000,000 
 
 
$ 89,000,000 
 
Requested Rate Increase Related to Net Energy Costs
 
 
 
 
 
 
100,000,000 
 
 
 
 
Sharing Level For Fac
 
 
 
 
 
 
95.00% 
 
 
 
 
Public Utilities, Requested Return on Equity, Percentage
 
 
 
 
 
 
10.40% 
 
 
9.25% 
 
Public Utilities, Requested Equity Capital Structure, Percentage
 
 
 
 
 
 
51.80% 
 
 
 
 
Rate Base
 
 
 
 
 
 
7,000,000,000 
 
 
 
 
Regulatory assets
1,582,000,000 
1,240,000,000 
 
695,000,000 
534,000,000 
 
 
36,000,000 
 
 
 
Customer Refund Liability, Current
 
 
 
 
 
 
 
 
 
 
26,000,000 
Interest Expense
341,000,000 
398,000,000 
392,000,000 
211,000,000 
210,000,000 
223,000,000 
 
 
 
 
1,000,000 
Energy Efficiency Program Spending
 
 
 
 
 
 
 
 
135,000,000 
 
 
Incentive Award if Energy Efficiency Goals Are Achieved
 
 
 
 
 
 
 
 
$ 25,000,000 
 
 
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% 
 
 
Rate And Regulatory Matters (Narrative-Illinois) (Details) (USD $)
12 Months Ended 3 Months Ended 3 Months Ended 12 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2014
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Final Rate Order
Gas Distribution
Dec. 31, 2014
Ameren Illinois Company
Final Rate Order
Electric Distribution
Dec. 9, 2013
Ameren Illinois Company
Final Rate Order
Electric Distribution
Dec. 31, 2014
Ameren Illinois Company
IEMA Revenue Requirement Reconciliation
IEIMA
Electric Distribution
Dec. 31, 2013
Ameren Illinois Company
IEMA Revenue Requirement Reconciliation
IEIMA
Electric Distribution
Dec. 31, 2013
Ameren Illinois Company
Rate order appeal [Member]
Gas Distribution
Dec. 31, 2014
ATXI
Jan. 31, 2015
Subsequent Event
Ameren Illinois Company
Pending Rate Case [Member]
Gas Distribution
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
Regulatory assets
$ 1,582,000,000 
$ 1,240,000,000 
$ 883,000,000 
$ 701,000,000 
 
 
 
$ 101,000,000 
 
 
 
 
Current regulatory assets
295,000,000 
156,000,000 
129,000,000 
38,000,000 
 
 
 
65,000,000 
 
 
 
 
Current regulatory liabilities
106,000,000 
216,000,000 
84,000,000 
159,000,000 
 
 
 
 
65,000,000 
 
 
 
Authorized increase in revenue from utility service
 
 
 
 
32,000,000 
 
 
204,000,000 
 
 
 
 
Disallowed costs associated with debt redemption
 
 
 
 
 
 
15,000,000 
 
 
 
 
 
Allowed Costs Associated with Debt Redemption
 
 
 
 
 
11,000,000 
 
 
 
 
 
 
Public Utilities, Requested Rate Increase (Decrease), Amount
 
 
 
 
 
 
 
 
 
 
 
53,000,000 
Public Utilities, Requested Return on Equity, Percentage
 
 
 
 
 
 
 
 
 
 
 
10.25% 
Public Utilities, Requested Equity Capital Structure, Percentage
 
 
 
 
 
 
 
 
 
 
 
50.00% 
Rate base
 
 
 
 
1,100,000,000 
 
 
 
 
 
 
1,200,000,000 
Public Utilities, Approved Return on Equity, Percentage
 
 
 
 
9.10% 
 
 
 
 
10.40% 
 
 
Percent of capital structure composed of equity
 
 
 
 
51.70% 
 
 
 
 
 
 
 
Projected Transmission Project Costs
 
 
 
 
 
 
 
 
 
 
$ 150,000,000 
 
Rate And Regulatory Matters Rate and Regulatory Matters (Narrative-Federal) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended 1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Nov. 30, 2014
Midwest Independent Transmission System Operator, Inc [Member]
Pending Ferc Case [Member]
Dec. 31, 2014
Midwest Independent Transmission System Operator, Inc [Member]
Pending Ferc Case [Member]
Dec. 31, 2014
New England Transmission Owners [Member]
Pending Ferc Case [Member]
Sep. 30, 2014
Wholesale Distribution Rate Case
Feb. 28, 2015
Subsequent Event
Midwest Independent Transmission System Operator, Inc [Member]
Pending Ferc Case [Member]
Dec. 31, 2014
Minimum
New England Transmission Owners [Member]
Pending Ferc Case [Member]
Dec. 31, 2014
Maximum
New England Transmission Owners [Member]
Pending Ferc Case [Member]
Dec. 31, 2014
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2012
Ameren Illinois Company
Dec. 31, 2014
Union Electric Company
Dec. 31, 2013
Union Electric Company
Dec. 31, 2012
Union Electric Company
Dec. 31, 2013
Union Electric Company
Entergy Refund
Dec. 31, 2012
Union Electric Company
Entergy Refund
Dec. 31, 2014
New Nuclear Energy Center COL [Member]
Union Electric Company
Dec. 31, 2014
New Nuclear Energy Center COL [Member]
Union Electric Company
Maximum
Dec. 31, 2014
Pending Ferc Case [Member]
Ameren Illinois Company
Maximum
Dec. 31, 2014
Pending Ferc Case [Member]
Union Electric Company
Power Purchase Agreement With Entergy Arkansas
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Current regulatory liabilities
$ 106 
$ 216 
 
 
 
 
$ 24 
 
 
 
$ 84 
$ 159 
 
$ 18 
$ 57 
 
 
 
 
 
 
 
Loss Contingency, Estimate of Possible Loss
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
22 
 
Customer Requested Rate on Equity
 
 
 
 
9.15% 
 
 
8.67% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Rate of return on common equity
 
 
 
 
12.38% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Public Utilities, Approved Return on Equity, Percentage
 
 
 
 
 
11.14% 
 
 
10.57% 
11.74% 
 
 
 
 
 
 
 
 
 
 
 
 
Incentive adder to FERC allowed base return on common equity
 
 
 
50 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceeds from Legal Settlements
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
31 
 
 
 
 
 
Purchased power
454 
502 
780 
 
 
 
 
 
 
 
343 
380 
705 
119 
127 
78 
 
24 
 
 
 
8 
Miscellaneous income
79 1
69 1
70 1
 
 
 
 
 
 
 
17 
10 
7 
60 
58 
63 
 
5 
 
 
 
 
Reduction To Under-recovered Asset
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2 
 
 
 
 
Investments in Power and Distribution Projects
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
$ 69 
$ 100 
 
 
Rate And Regulatory Matters (Schedule Of Regulatory Assets And Liabilities) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
$ 295 
$ 156 
Regulatory assets
1,582 
1,240 
Current regulatory liabilities
106 
216 
Regulatory liabilities
1,850 
1,705 
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
163 
118 
Regulatory assets
695 
534 
Current regulatory liabilities
18 
57 
Regulatory liabilities
1,147 
1,041 
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
129 
38 
Regulatory assets
883 
701 
Current regulatory liabilities
84 
159 
Regulatory liabilities
703 
664 
Under-Recovered FAC
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
128 1 2
104 1 2
Under-Recovered FAC |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
128 1 2
104 1 2
Under-Recovered FAC |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
0 1 2
 
Under-Recovered Illinois Electric Power Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
2 3
1 3
Under-Recovered Illinois Electric Power Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
2 3
1 3
Under-Recovered PGA
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
20 3
1 3
Under-Recovered PGA |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
20 3
1 3
MTM Derivative Losses
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
74 4
50 4
Regulatory assets
158 4
126 4
MTM Derivative Losses |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
32 4
14 4
Regulatory assets
14 4
8 4
MTM Derivative Losses |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
42 4
36 4
Regulatory assets
144 4
118 4
Energy Efficiency Rider
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
3 5
 
Regulatory liabilities
39 5
36 5
Energy Efficiency Rider |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
3 5
 
Regulatory liabilities
 
3 5
Energy Efficiency Rider |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
39 5
33 5
IEMA Revenue Requirement Reconciliation
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
65 1 6
 
Regulatory assets
101 1 6
65 1 6
Current regulatory liabilities
 
65 6
IEMA Revenue Requirement Reconciliation |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
65 1 6
 
Regulatory assets
101 1 6
65 1 6
Current regulatory liabilities
 
65 6
FERC Revenue Requirement Reconciliation
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory assets
3 1 7
 
Regulatory assets
12 1 7
5 1 7
Current regulatory liabilities
11 7
 
Regulatory liabilities
 
10 7
FERC Revenue Requirement Reconciliation |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
8 1 7
 
Current regulatory liabilities
11 7
 
Regulatory liabilities
 
10 7
Pension And Postretirement Benefit Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
423 8
184 8
Pension And Postretirement Benefit Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
148 8
44 8
Pension And Postretirement Benefit Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
275 8
140 8
Income Taxes
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
256 9
237 9
Regulatory liabilities
55 10
40 10
Income Taxes |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
253 9
230 9
Regulatory liabilities
41 10
37 10
Income Taxes |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
3 9
7 9
Regulatory liabilities
14 10
3 10
Asset Retirement Obligation
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
5 11
5 11
Regulatory liabilities
182 11
146 11
Asset Retirement Obligation |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
182 11
146 11
Asset Retirement Obligation |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
5 11
5 11
Callaway Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
36 1 12
40 1 12
Callaway Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
36 1 12
40 1 12
Unamortized Loss On Reacquired Debt
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
152 1 13
151 1 13
Unamortized Loss On Reacquired Debt |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
72 1 13
77 1 13
Unamortized Loss On Reacquired Debt |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
80 1 13
74 1 13
Recoverable Costs Contaminated Facilities
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
251 14
271 14
Recoverable Costs Contaminated Facilities |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
251 14
271 14
Storm Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
3 15
8 15
Storm Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
 
5 15
Storm Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
3 15
3 15
Demand-Side Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
44 1 16
58 1 16
Demand-Side Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
44 1 16
58 1 16
Reserve For Workers' Compensation Liabilities
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
14 17
12 17
Reserve For Workers' Compensation Liabilities |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
7 17
6 17
Reserve For Workers' Compensation Liabilities |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
7 17
6 17
Credit Facilities Fees
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
5 18
5 18
Credit Facilities Fees |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
5 18
5 18
Common Stock Issuance Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
2 19
4 19
Common Stock Issuance Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
2 19
4 19
Construction Accounting For Pollution Control Equipment
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
21 1 20
22 1 20
Construction Accounting For Pollution Control Equipment |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
21 1 20
22 1 20
Solar Rebates
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
88 1 21
27 1 21
Solar Rebates |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
88 1 21
27 1 21
Other
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
11 22
20 22
Regulatory liabilities
7 23
11 23
Other |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
5 22
8 22
Regulatory liabilities
7 23
11 23
Other |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory assets
6 22
12 22
Over-Recovered FAC
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
0 2
26 2
Over-Recovered FAC |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
0 2
26 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
26 3
51 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
26 3
51 3
Over-Recovered PGA
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
27 3
34 3
Over-Recovered PGA |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
2 3
5 3
Over-Recovered PGA |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
25 3
29 3
MTM Derivative Gains
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
17 4
27 4
MTM Derivative Gains |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
16 4
26 4
MTM Derivative Gains |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
1 4
1 4
Wholesale Distribution Refund
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
 
13 24
Wholesale Distribution Refund |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
 
13 24
Refund Reserves for FERC Orders and Audit Findings [Member]
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
25 25
 
Refund Reserves for FERC Orders and Audit Findings [Member] |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Current regulatory liabilities
21 25
 
Uncertain tax positions tracker [Member]
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
7 26
1 26
Uncertain tax positions tracker [Member] |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
7 26
1 26
Removal Costs
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
1,529 27
1,438 27
Removal Costs |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
886 27
828 27
Removal Costs |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
643 27
610 27
Bad Debt Rider
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
7 28
8 28
Bad Debt Rider |
Ameren Illinois Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
7 28
8 28
Pension And Postretirement Benefit Costs Tracker
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
24 29
15 29
Pension And Postretirement Benefit Costs Tracker |
Union Electric Company
 
 
Rate And Regulatory Matters [Line Items]
 
 
Regulatory liabilities
$ 24 29
$ 15 29
[16] (o)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.The amortization period for costs incurred from August 2012 through December 2012 will be determined in the July 2014 electric rate case.
Property And Plant, Net (Schedule Of Property And Plant, Net) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
equipment
Dec. 31, 2013
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
 26,198 1
$ 23,701 1
Accumulated depreciation and amortization
9,759 1
8,644 1
Property and plant, before construction work in progress
16,439 1
15,057 1
Property, Plant and Equipment, Net
17,424 1
16,205 1
Number of combustion turbine electric generation equipment under capital lease agreements
2 
 
Number of capital lease agreements
2 
 
Capital lease agreements, gross asset value
233 
228 
Total accumulated depreciation, capital lease agreements
66 
56 
Held-to-maturity Securities
294 
299 
Electric
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
23,913 1
21,726 1
Gas
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
2,285 1
1,975 1
Nuclear Fuel
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
209 1
246 1
Other Energy
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
776 1
902 1
Union Electric Company
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
17,483 1
16,377 1
Accumulated depreciation and amortization
7,086 1
6,766 1
Property and plant, before construction work in progress
10,397 1
9,611 1
Property, Plant and Equipment, Net
10,867 1
10,452 1
Union Electric Company |
Electric
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
17,052 1
15,964 1
Union Electric Company |
Gas
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
431 1
413 1
Union Electric Company |
Nuclear Fuel
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
209 1
246 1
Union Electric Company |
Other Energy
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
261 1
595 1
Ameren Illinois Company
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
8,371 
6,988 
Accumulated depreciation and amortization
2,422 
1,627 
Property and plant, before construction work in progress
5,949 
5,361 
Property, Plant and Equipment, Net
6,165 
5,589 
Ameren Illinois Company |
Electric
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
6,517 
5,426 
Ameren Illinois Company |
Gas
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
1,854 
1,562 
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
216 
228 
Other
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
344 
336 
Accumulated depreciation and amortization
251 
251 
Property and plant, before construction work in progress
93 
85 
Property, Plant and Equipment, Net
392 
164 
Other |
Electric
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
344 
336 
Other |
Gas
 
 
Property, Plant and Equipment [Line Items]
 
 
Property and plant, at original cost
0 
0 
Other |
Nuclear Fuel
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
0 
0 
Other |
Other Energy
 
 
Property, Plant and Equipment [Line Items]
 
 
Construction work in progress
$ 299 
$ 79 
Property And Plant, Net (Accrued Capital Expenditures) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
$ 181 1
$ 175 1
$ 107 1
Union Electric Company
 
 
 
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
72 
74 
63 
Ameren Illinois Company
 
 
 
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
59 
86 
37 
Nuclear Fuel
 
 
 
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
13 1
8 1
8 1
Nuclear Fuel |
Union Electric Company
 
 
 
Property, Plant and Equipment [Line Items]
 
 
 
Accrued capital expenditures
$ 13 
$ 8 
$ 8 
Short-Term Debt And Liquidity (Narrative) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Illinois Credit Agreement 2012 |
Maximum
 
 
Line of Credit Facility [Line Items]
 
 
Line of credit facility, maximum borrowing capacity
$ 1,300,000,000.0 
 
Illinois Credit Agreement 2012 |
Ameren Illinois Company
 
 
Line of Credit Facility [Line Items]
 
 
Line of credit facility, maximum borrowing capacity
800,000,000 
 
Actual debt-to-capital ratio
0.47 
 
Missouri Credit Agreement 2012 |
Maximum
 
 
Line of Credit Facility [Line Items]
 
 
Line of credit facility, maximum borrowing capacity
1,200,000,000.0 
 
Missouri Credit Agreement 2012 |
Union Electric Company
 
 
Line of Credit Facility [Line Items]
 
 
Line of credit facility, maximum borrowing capacity
800,000,000 
 
Actual debt-to-capital ratio
0.49 
 
Credit Agreements 2012
 
 
Line of Credit Facility [Line Items]
 
 
Line of credit facility, maximum borrowing capacity
1,400,000,000.0 
 
Covenant terms, default provisions, maximum indebtedness
75,000,000 
 
Multiyear Credit Facility
 
 
Line of Credit Facility [Line Items]
 
 
Line of credit facility, maximum borrowing capacity
2,100,000,000 
 
Number of lenders
24 
 
Line of credit facility, maximum borrowing capacity, per lender
115,000,000 
 
Actual debt-to-capital ratio
0.50 
 
Minimum ratio of consolidated funds from operations plus interest expense to consolidated interest expense as of balance sheet date
2.0 to 1.0 
 
Letters of credit portion of aggregate commitment
25.00% 
 
Line of Credit Facility, Commitment Fee Amount
100,000,000 
 
Multiyear Credit Facility |
Maximum
 
 
Line of Credit Facility [Line Items]
 
 
Actual debt-to-capital ratio
0.65 
 
Utilities
 
 
Line of Credit Facility [Line Items]
 
 
Short Term Debt, Weighted Average Interest Rate During Period
0.19% 
0.14% 
New Ameren Energy Resources Company, LLC
 
 
Line of Credit Facility [Line Items]
 
 
Line of Credit Facility, Commitment Fee Amount
$ 9,000,000 
 
Short-Term Debt And Liquidity (Schedule Of Maximum Aggregate Amount Available On Credit Agreements) (Details) (USD $)
Dec. 31, 2014
Illinois Credit Agreement 2012 |
Parent Company
 
Line of Credit Facility [Line Items]
 
Line of credit facility, maximum borrowing capacity
$ 500,000,000 
Illinois Credit Agreement 2012 |
Ameren Illinois Company
 
Line of Credit Facility [Line Items]
 
Line of credit facility, maximum borrowing capacity
800,000,000 
Missouri Credit Agreement 2012 |
Parent Company
 
Line of Credit Facility [Line Items]
 
Line of credit facility, maximum borrowing capacity
700,000,000 
Missouri Credit Agreement 2012 |
Union Electric Company
 
Line of Credit Facility [Line Items]
 
Line of credit facility, maximum borrowing capacity
$ 800,000,000 
Short-Term Debt And Liquidity Short-Term Debt And Liquidity (Commercial Paper) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Commercial Paper
 
 
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
$ 639 
$ 54 
Commercial paper outstanding
714 
368 
Weighted average interest rate
0.36% 
0.56% 
Peak short-term borrowings
910 
368 
Peak short-term borrowings interest rate
0.75% 
0.85% 
Union Electric Company
 
 
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
110 
0 
Weighted average interest rate
0.38% 
0.00% 
Peak short-term borrowings
495 
0 
Peak short-term borrowings interest rate
0.70% 
0.00% 
Ameren Illinois Company
 
 
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
165 
0 
Weighted average interest rate
0.32% 
0.00% 
Peak short-term borrowings
300 
0 
Peak short-term borrowings interest rate
0.60% 
0.00% 
Ameren Illinois Company |
Commercial Paper
 
 
Line of Credit Facility [Line Items]
 
 
Commercial paper outstanding
32 
0 
Ameren Missouri [Member] |
Commercial Paper
 
 
Line of Credit Facility [Line Items]
 
 
Commercial paper outstanding
97 
0 
Ameren (parent) [Domain]
 
 
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
423 
54 
Weighted average interest rate
0.36% 
0.56% 
Peak short-term borrowings
625 
368 
Peak short-term borrowings interest rate
0.75% 
0.85% 
Ameren (parent) [Domain] |
Commercial Paper
 
 
Line of Credit Facility [Line Items]
 
 
Commercial paper outstanding
$ 585 
$ 368 
Long-Term Debt And Equity Financings (Narrative) (Details) (USD $)
12 Months Ended 1 Months Ended 12 Months Ended 12 Months Ended 1 Months Ended 1 Months Ended 3 Months Ended 3 Months Ended 3 Months Ended 1 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2014
Union Electric Company
Dec. 31, 2013
Union Electric Company
Dec. 31, 2012
Union Electric Company
Dec. 31, 2014
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2012
Ameren Illinois Company
Jan. 31, 2014
Ameren Illinois Company
Jan. 31, 2014
Ameren Illinois Company
Environmental Improvement And Pollution Control Revenue Bonds
Dec. 31, 2014
Parent Company
Dec. 31, 2013
Parent Company
Dec. 31, 2012
Parent Company
May 31, 2014
Parent Company
Oct. 31, 2013
Parent Company
Dec. 31, 2014
Ameren Missouri and Ameren Illinois
Dec. 31, 2014
Series1993570 Due2024 [Member]
Ameren Illinois Company
Environmental Improvement And Pollution Control Revenue Bonds
May 31, 2014
Senior Unsecured Notes8875 Due2014 [Member]
Parent Company
Dec. 31, 2014
Senior Unsecured Notes8875 Due2014 [Member]
Parent Company
Dec. 31, 2013
Senior Unsecured Notes8875 Due2014 [Member]
Parent Company
Apr. 30, 2014
Senior Secured Notes, 3.50%, Due 2024 [Member]
Union Electric Company
Secured Debt
May 31, 2014
5.50% Senior secured notes due 2014
Union Electric Company
Secured Debt
Dec. 31, 2014
5.50% Senior secured notes due 2014
Union Electric Company
Secured Debt
May 15, 2014
5.50% Senior secured notes due 2014
Union Electric Company
Secured Debt
Dec. 31, 2013
5.50% Senior secured notes due 2014
Union Electric Company
Secured Debt
Dec. 31, 2013
Senior Secured Notes 4.80% Due 2043
Ameren Illinois Company
Secured Debt
Dec. 31, 2014
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, 2013
1993 5.45% Series due 2028
Union Electric Company
Environmental Improvement And Pollution Control Revenue Bonds
Dec. 31, 2014
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, 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
Jun. 30, 2014
Senior Secured Notes, 4.30%, Due 2044 [Member] [Member]
Ameren Illinois Company
Secured Debt
Dec. 31, 2014
Senior Secured Notes, 3 Point 25, Due 2025 [Member]
Ameren Illinois Company
Secured Debt
Dec. 31, 2014
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, 2014
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, 2014
Series 1993 5.90% Due 2023
Ameren Illinois Company
Secured Debt
Jan. 31, 2014
Series 1993 5.90% Due 2023
Ameren Illinois Company
Environmental Improvement And Pollution Control Revenue Bonds
Dec. 31, 2014
Series 1993 5.90% Due 2023
Ameren Illinois Company
Environmental Improvement And Pollution Control Revenue Bonds
Dec. 31, 2013
Series 1993 5.90% Due 2023
Ameren Illinois Company
Environmental Improvement And Pollution Control Revenue Bonds
Dec. 31, 2014
Minimum
Ameren Illinois Company
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 
 
150,000,000 
150,000,000 
 
45,000,000 
45,000,000 
 
 
 
 
 
 
8,600,000.0 
4,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Repayments of Other Long-term Debt
$ 697,000,000 
$ 399,000,000 
$ 760,000,000 
$ 109,000,000 
$ 249,000,000 
$ 427,000,000 
$ 163,000,000 
$ 150,000,000 
$ 333,000,000 
 
 
$ 425,000,000 
$ 0 
$ 0 
 
 
 
 
$ 425,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Debt instrument face amount
 
 
 
 
 
 
 
 
 
1,000,000 1
 
 
 
 
 
 
 
1,000,000 2
 
 
425,000,000 
350,000,000 
 
0 3
 
104,000,000 3
280,000,000 4
280,000,000 4
 
 
1,000,000 2
 
 
 
250,000,000 
300,000,000 4 5
400,000,000 4 5
400,000,000 4 5
485,000,000 3 6
485,000,000 3 6
1,000,000 2
 
1,000,000 2 7
32,000,000 7
 
Long-term debt interest rate
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
8.875% 
8.875% 
 
3.50% 
 
5.50% 
5.50% 
 
4.80% 
4.80% 
8.875% 
 
5.45% 
5.45% 
 
4.65% 
4.30% 
3.25% 
2.70% 
 
3.90% 
 
5.90% 
 
5.90% 
 
 
Proceeds from issuance of secured debt
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
348,000,000 
 
 
 
 
276,000,000 
 
 
 
 
 
 
 
246,000,000 
298,000,000 
 
 
 
 
 
 
 
 
 
Redemptions of long-term debt
 
 
 
 
 
 
 
 
 
 
$ 163,000,000 
 
 
 
 
 
 
 
 
 
 
 
$ 104,000,000 
 
 
 
 
 
$ 150,000,000 
$ 44,000,000 
 
 
$ 200,000,000 
 
 
 
 
 
 
 
 
$ 32,000,000 8
 
 
 
Bonds interest rate assumption
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Dividend rate on preferred shares, percentage
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
6.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Common stock equity to capitalization ratio
 
 
 
 
 
 
53.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
30.00% 
[3] 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 senior secured notes currently outstanding, 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
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2014
Parent Company
Dec. 31, 2013
Parent Company
Dec. 31, 2014
Parent Company
8.875% Senior unsecured notes due 2014
May 31, 2014
Parent Company
8.875% Senior unsecured notes due 2014
Dec. 31, 2013
Parent Company
8.875% Senior unsecured notes due 2014
Dec. 31, 2014
Union Electric Company
Dec. 31, 2013
Union Electric Company
Dec. 31, 2014
Union Electric Company
City Of Bowling Green Capital Lease Peno Creek Ct
Dec. 31, 2013
Union Electric Company
City Of Bowling Green Capital Lease Peno Creek Ct
Dec. 31, 2014
Union Electric Company
Audrain County Capital Lease Audrain County Ct
Dec. 31, 2013
Union Electric Company
Audrain County Capital Lease Audrain County Ct
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2014
Ameren Illinois Company
Jan. 31, 2014
Ameren Illinois Company
Oct. 31, 2013
Secured Debt
Union Electric Company
4.65% Senior secured notes due 2013
Dec. 31, 2014
Secured Debt
Union Electric Company
5.50% Senior secured notes due 2014
May 15, 2014
Secured Debt
Union Electric Company
5.50% Senior secured notes due 2014
Dec. 31, 2013
Secured Debt
Union Electric Company
5.50% Senior secured notes due 2014
Dec. 31, 2014
Secured Debt
Union Electric Company
4.75% Senior secured notes due 2015
Dec. 31, 2013
Secured Debt
Union Electric Company
4.75% Senior secured notes due 2015
Dec. 31, 2014
Secured Debt
Union Electric Company
5.40% Senior secured notes due 2016
Dec. 31, 2013
Secured Debt
Union Electric Company
5.40% Senior secured notes due 2016
Dec. 31, 2014
Secured Debt
Union Electric Company
6.40% Senior secured notes due 2017
Dec. 31, 2013
Secured Debt
Union Electric Company
6.40% Senior secured notes due 2017
Dec. 31, 2014
Secured Debt
Union Electric Company
6.00% Senior secured notes due 2018
Dec. 31, 2013
Secured Debt
Union Electric Company
6.00% Senior secured notes due 2018
Dec. 31, 2014
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2018
Dec. 31, 2013
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2018
Dec. 31, 2014
Secured Debt
Union Electric Company
6.70% Senior secured notes due 2019
Dec. 31, 2013
Secured Debt
Union Electric Company
6.70% Senior secured notes due 2019
Dec. 31, 2014
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2019
Dec. 31, 2013
Secured Debt
Union Electric Company
5.10% Senior secured notes due 2019
Dec. 31, 2014
Secured Debt
Union Electric Company
5.00% Senior secured notes due 2020
Dec. 31, 2013
Secured Debt
Union Electric Company
5.00% Senior secured notes due 2020
Dec. 31, 2014
Secured Debt
Union Electric Company
Senior Secured Notes350 Due2024 [Member]
Dec. 31, 2014
Secured Debt
Union Electric Company
5.50% Senior secured notes due 2034
Dec. 31, 2013
Secured Debt
Union Electric Company
5.50% Senior secured notes due 2034
Dec. 31, 2014
Secured Debt
Union Electric Company
5.30% Senior secured notes due 2037
Dec. 31, 2013
Secured Debt
Union Electric Company
5.30% Senior secured notes due 2037
Dec. 31, 2014
Secured Debt
Union Electric Company
8.45% Senior secured notes due 2039
Dec. 31, 2013
Secured Debt
Union Electric Company
8.45% Senior secured notes due 2039
Dec. 31, 2014
Secured Debt
Union Electric Company
3.90% Senior secured notes due 2042
Dec. 31, 2013
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, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.20% Due 2016
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.20% Due 2016
Dec. 31, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.25% Due 2016
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.25% Due 2016
Dec. 31, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.125% Due 2017
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.125% Due 2017
Dec. 31, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.25% Due 2018
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.25% Due 2018
Dec. 31, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes 9.75% Due 2018
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 9.75% Due 2018
Dec. 31, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes, 2.70%, Due 2022
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes, 2.70%, Due 2022
Dec. 31, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes, 3 Point 25, Due 2025 [Member]
Dec. 31, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.125% Due 2028
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 6.125% Due 2028
Dec. 31, 2014
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, 2014
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, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes 4.80% Due 2043
Dec. 31, 2013
Secured Debt
Ameren Illinois Company
Senior Secured Notes 4.80% Due 2043
Dec. 31, 2014
Secured Debt
Ameren Illinois Company
Senior Secured Notes430 Due2044 [Member]
Dec. 31, 2014
Secured Debt
Ameren Illinois Company
Series 1993 5.90% Due 2023
Dec. 31, 2014
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
1992 Series due 2022
Dec. 31, 2014
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, 2014
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 A due 2033
Dec. 31, 2014
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 B due 2033
Dec. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1998 Series C due 2033
Dec. 31, 2013
Environmental Improvement And Pollution Control Revenue Bonds
Union Electric Company
1998 Series C due 2033
Dec. 31, 2014
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 1993 5.90% Due 2023
Dec. 31, 2014
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 1994 A 5.70% Due 2024
Dec. 31, 2014
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-1 1993 5.95% Due 2026
Dec. 31, 2014
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 C-2 1993 5.70% Due 2026
Dec. 31, 2014
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
Series B-1 1993 Due 2028
Dec. 31, 2014
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
Series1998A 5.40% Due 2028
Dec. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds
Ameren Illinois Company
Series1998B 5.40% Due 2028
Dec. 31, 2013
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 
 
 
 
 
 
 
 
 
$ 1,000,000 1
 
$ 0 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
$ 199,000,000 2
$ 199,000,000 2
$ 329,000,000 2 3
$ 329,000,000 2 3
$ 244,000,000 2
$ 244,000,000 2
$ 85,000,000 2
$ 85,000,000 2
$ 350,000,000 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
 
$ 54,000,000 4
$ 54,000,000 4
$ 75,000,000 5
$ 75,000,000 5
$ 250,000,000 5 6
$ 250,000,000 5 6
$ 144,000,000 5 6
$ 144,000,000 5 6
$ 313,000,000 5 6
$ 313,000,000 5 6
$ 400,000,000 5 6
$ 400,000,000 5 6
$ 300,000,000 5 6
$ 60,000,000 5
$ 60,000,000 5
$ 61,000,000 5
$ 61,000,000 5
$ 42,000,000 4
$ 42,000,000 4
$ 280,000,000 5
$ 280,000,000 5
$ 250,000,000 5
$ 1,000,000 7
$ 47,000,000 8 9
$ 47,000,000 8 9
$ 1,000,000 7
 
$ 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
$ 1,000,000 10 7
$ 32,000,000 10
$ 1,000,000 1
$ 36,000,000 1
 
$ 35,000,000 11
 
$ 8,000,000 11
$ 17,000,000 11 8
$ 17,000,000 11 8
 
$ 19,000,000 1
 
$ 33,000,000 1
Capital lease obligations
 
 
 
 
 
 
 
 
 
54,000,000 
59,000,000 
240,000,000 
240,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fair-market value adjustments
 
 
 
 
 
 
 
 
 
 
 
 
 
4,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Long-term debt, gross
 
 
 
 
 
 
 
4,005,000,000 
3,764,000,000 
 
 
 
 
1,863,000,000 
2,246,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Less: Unamortized discount and premium
 
 
 
 
 
 
 
6,000,000 
7,000,000 
 
 
 
 
7,000,000 
5,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Less: Maturities due within one year
(120,000,000)
(534,000,000)
0 
(425,000,000)
 
 
 
(120,000,000)
(109,000,000)
 
 
 
 
0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Long-term Debt, Net
$ 6,120,000,000 
$ 5,504,000,000 
 
 
 
 
 
$ 3,879,000,000 
$ 3,648,000,000 
 
 
 
 
$ 1,856,000,000 
$ 2,241,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Long-term debt interest rate
 
 
 
 
8.875% 
8.875% 
 
 
 
 
 
 
 
 
 
 
4.65% 
5.50% 
5.50% 
 
4.75% 
 
5.40% 
 
6.40% 
 
6.00% 
 
5.10% 
 
6.70% 
 
5.10% 
 
5.00% 
 
3.50% 
5.50% 
 
5.30% 
 
8.45% 
 
3.90% 
 
8.875% 
6.20% 
 
6.25% 
 
6.125% 
 
6.25% 
 
9.75% 
 
2.70% 
 
3.25% 
6.125% 
 
6.70% 
 
6.70% 
 
4.80% 
4.80% 
4.30% 
5.90% 
 
 
5.45% 
5.45% 
 
 
 
 
 
 
5.90% 
 
5.70% 
 
5.95% 
 
5.70% 
 
 
 
5.40% 
 
5.40% 
 
Long-term debt maturity date
 
 
 
 
2014 
 
 
 
 
2022 
 
2023 
 
 
 
 
 
2014 
 
 
2015 
 
2016 
 
2017 
 
2018 
 
2018 
 
2019 
 
2019 
 
2020 
 
2024 
2034 
 
2037 
 
2039 
 
2042 
 
 
2016 
 
2016 
 
2017 
 
2018 
 
2018 
 
2022 
 
2025 
2028 
 
2036 
 
2036 
 
2043 
 
2044 
 
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 senior secured notes currently outstanding, 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 Average Interest Rates) (Details)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
1992 Series due 2022 |
Union Electric Company
 
 
Debt Instrument [Line Items]
 
 
Debt instrument, interest rate during period
0.10% 
0.17% 
1998 Series A due 2033 |
Union Electric Company
 
 
Debt Instrument [Line Items]
 
 
Debt instrument, interest rate during period
0.26% 
0.34% 
1998 Series B due 2033 |
Union Electric Company
 
 
Debt Instrument [Line Items]
 
 
Debt instrument, interest rate during period
0.27% 
0.33% 
1998 Series C due 2033 |
Union Electric Company
 
 
Debt Instrument [Line Items]
 
 
Debt instrument, interest rate during period
0.26% 
0.34% 
Series B-1 1993 Due 2028 |
Ameren Illinois Company
 
 
Debt Instrument [Line Items]
 
 
Debt instrument, interest rate during period
0.21% 
0.14% 
Secured Debt |
3.90% Senior secured notes due 2042 |
Union Electric Company
 
 
Debt Instrument [Line Items]
 
 
Long-term debt interest rate
3.90% 
 
Long-Term Debt And Equity Financings (Schedule Of Maturities Of Long-Term Debt) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Debt Instrument [Line Items]
 
 
2015
$ 120 
 
2016
395 
 
2017
681 
 
2018
840 
 
2019
581 
 
Thereafter
3,634 
 
Total
6,251 
 
Union Electric Company
 
 
Debt Instrument [Line Items]
 
 
2015
120 1
 
2016
266 1
 
2017
431 1
 
2018
383 1
 
2019
581 1
 
Thereafter
2,224 1
 
Total
4,005 1
 
Unamortized discount and premium
6 
7 
Ameren Illinois Company
 
 
Debt Instrument [Line Items]
 
 
2016
129 1
 
2017
250 1
 
2018
457 1
 
Thereafter
1,410 1
 
Total
2,246 1
 
Unamortized discount and premium
$ 5 
$ 7 
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, 2014
Dec. 31, 2013
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 (Schedule of Debt Redemptions) (Details) (Ameren Illinois Company, USD $)
1 Months Ended
Jan. 31, 2014
Dec. 31, 2014
Dec. 31, 2013
Debt Instrument [Line Items]
 
 
 
Debt instrument face amount
$ 1,000,000 1
 
 
Secured Debt |
Senior Secured Notes 9.75% Due 2018
 
 
 
Debt Instrument [Line Items]
 
 
 
Debt instrument face amount
 
313,000,000 2 3
313,000,000 2 3
Secured Debt |
Series 1993 5.90% Due 2023
 
 
 
Debt Instrument [Line Items]
 
 
 
Debt instrument face amount
 
1,000,000 4
 
Secured Debt |
Senior Secured Notes 6.25% Due 2018
 
 
 
Debt Instrument [Line Items]
 
 
 
Debt instrument face amount
 
144,000,000 2 3
144,000,000 2 3
Environmental Improvement And Pollution Control Revenue Bonds
 
 
 
Debt Instrument [Line Items]
 
 
 
Redemptions of long-term debt
163,000,000 
 
 
Environmental Improvement And Pollution Control Revenue Bonds |
Series 1993 5.90% Due 2023
 
 
 
Debt Instrument [Line Items]
 
 
 
Redemptions of long-term debt
32,000,000 5
 
 
Debt instrument face amount
 
1,000,000 4 6
32,000,000 6
Environmental Improvement And Pollution Control Revenue Bonds |
Series 1994 A 5.70% Due 2024
 
 
 
Debt Instrument [Line Items]
 
 
 
Redemptions of long-term debt
36,000,000 5
 
 
Debt instrument face amount
 
1,000,000 1
36,000,000 1
Environmental Improvement And Pollution Control Revenue Bonds |
Series C-1 1993 5.95% Due 2026
 
 
 
Debt Instrument [Line Items]
 
 
 
Redemptions of long-term debt
35,000,000 
 
 
Debt instrument face amount
 
 
35,000,000 7
Environmental Improvement And Pollution Control Revenue Bonds |
Series C-2 1993 5.70% Due 2026
 
 
 
Debt Instrument [Line Items]
 
 
 
Redemptions of long-term debt
8,000,000 
 
 
Debt instrument face amount
 
 
8,000,000 7
Environmental Improvement And Pollution Control Revenue Bonds |
Series1998A 5.40% Due 2028
 
 
 
Debt Instrument [Line Items]
 
 
 
Redemptions of long-term debt
19,000,000 
 
 
Debt instrument face amount
 
 
19,000,000 1
Environmental Improvement And Pollution Control Revenue Bonds |
Series1998B 5.40% Due 2028
 
 
 
Debt Instrument [Line Items]
 
 
 
Redemptions of long-term debt
33,000,000 
 
 
Debt instrument face amount
 
 
$ 33,000,000 1
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, 2014
Union Electric Company
 
Debt Instrument [Line Items]
 
Bonds Issuable Based On Coverage Ratio
$ 3,605 1
Preferred Stock Issuable Based On Coverage Ratio
2,568 
Retired Bond Capacity
832 
Union Electric Company |
Actual Interest Coverage Ratio
 
Debt Instrument [Line Items]
 
Interest Coverage Ratio
4.3 
Dividend Coverage Ratio
115.1 
Ameren Illinois Company
 
Debt Instrument [Line Items]
 
Bonds Issuable Based On Coverage Ratio
3,358 1 2
Preferred Stock Issuable Based On Coverage Ratio
208 
Retired Bond Capacity
$ 204 
Ameren Illinois Company |
Actual Interest Coverage Ratio
 
Debt Instrument [Line Items]
 
Interest Coverage Ratio
6.4 
Dividend Coverage Ratio
2.7 
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Other Nonoperating Income (Expense) [Line Items]
 
 
 
Allowance for equity funds used during construction
$ 34 1
$ 37 1
$ 36 1
Interest income on industrial development revenue bonds
27 1
27 1
28 1
Interest and dividend income
10 1 2
3 1
4 1 3
Other
8 1 4
2 1
2 1
Total miscellaneous income
79 1
69 1
70 1
Donations
10 1
12 1
24 1 5
Other
12 1
14 1
13 1
Total miscellaneous expense
22 1
26 1
37 1
Union Electric Company
 
 
 
Other Nonoperating Income (Expense) [Line Items]
 
 
 
Allowance for equity funds used during construction
32 
31 
31 
Interest income on industrial development revenue bonds
27 
27 
28 
Interest and dividend income
1 
 
4 3
Total miscellaneous income
60 
58 
63 
Donations
6 
4 
9 
Other
6 
7 
5 
Total miscellaneous expense
12 
11 
14 
Ameren Illinois Company
 
 
 
Other Nonoperating Income (Expense) [Line Items]
 
 
 
Allowance for equity funds used during construction
2 
6 
5 
Interest and dividend income
7 2
2 
 
Other
8 4
2 
2 
Total miscellaneous income
17 
10 
7 
Donations
4 
4 
11 5
Other
4 
5 
6 
Total miscellaneous expense
8 
9 
17 
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, 2014
gal
Dec. 31, 2013
gal
Fuel Oils
 
 
Derivative [Line Items]
 
 
Quantity
50,000,000 1
66,000,000 1
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
136,000,000 
136,000,000 
Power
 
 
Derivative [Line Items]
 
 
Quantity
12,000,000 
14,000,000 
Uranium
 
 
Derivative [Line Items]
 
 
Quantity
332,000 
796,000 
Union Electric Company |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Quantity
50,000,000 1
66,000,000 1
Union Electric Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
28,000,000 
28,000,000 
Union Electric Company |
Power
 
 
Derivative [Line Items]
 
 
Quantity
1,000,000 
3,000,000 
Union Electric Company |
Uranium
 
 
Derivative [Line Items]
 
 
Quantity
332,000 
796,000 
Ameren Illinois Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
108,000,000 
108,000,000 
Ameren Illinois Company |
Power
 
 
Derivative [Line Items]
 
 
Quantity
11,000,000 
11,000,000 
Derivative Financial Instruments (Derivative Instruments Carrying Value) (Details) (Not Designated As Hedging Instrument, USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Derivative [Line Items]
 
 
Derivative assets
$ 19 
$ 34 
Derivative liabilities
232 
178 
Fuel Oils |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
2 
6 
Fuel Oils |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
 
3 
Fuel Oils |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
22 
2 
Fuel Oils |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
7 
1 
Natural Gas |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
2 
2 
Natural Gas |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
37 
32 
Natural Gas |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
19 
25 
Power |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
15 
23 
Power |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
14 
13 
Power |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
131 
99 
Uranium |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 
5 
Uranium |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
 
1 
Union Electric Company
 
 
Derivative [Line Items]
 
 
Derivative assets
18 
33 
Derivative liabilities
46 
24 
Union Electric Company |
Fuel Oils |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
2 
6 
Union Electric Company |
Fuel Oils |
Other assets
 
 
Derivative [Line Items]
 
 
Derivative assets
 
3 
Union Electric Company |
Fuel Oils |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
22 
2 
Union Electric Company |
Fuel Oils |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
7 
1 
Union Electric Company |
Natural Gas |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
1 
1 
Union Electric Company |
Natural Gas |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
6 
5 
Union Electric Company |
Natural Gas |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
6 
6 
Union Electric Company |
Power |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
15 
23 
Union Electric Company |
Power |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
3 
4 
Union Electric Company |
Uranium |
Other current liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 
5 
Union Electric Company |
Uranium |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
 
1 
Ameren Illinois Company
 
 
Derivative [Line Items]
 
 
Derivative assets
1 
1 
Derivative liabilities
186 
154 
Ameren Illinois Company |
Natural Gas |
Other current assets
 
 
Derivative [Line Items]
 
 
Derivative assets
1 
1 
Ameren Illinois Company |
Natural Gas |
MTM derivative liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
31 
27 
Ameren Illinois Company |
Natural Gas |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
13 
19 
Ameren Illinois Company |
Power |
MTM derivative liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
11 
9 
Ameren Illinois Company |
Power |
Other deferred credits and liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
$ 131 
$ 99 
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, 2014
Dec. 31, 2013
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
$ 106 
$ 216 
Current regulatory assets
295 
156 
Power
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
15 
 
Current regulatory assets
14 
 
Fuel Oils
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
21 
 
Natural Gas
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
2 
 
Current regulatory assets
37 
 
Uranium
 
 
Derivative [Line Items]
 
 
Current regulatory assets
2 
 
Regulatory Liabilities Or Assets |
Power
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(130)1
(89)
Regulatory Liabilities Or Assets |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(29)2
2 
Regulatory Liabilities Or Assets |
Natural Gas
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(54)3
(55)
Regulatory Liabilities Or Assets |
Uranium
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(2)4
(6)
Union Electric Company
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
18 
57 
Current regulatory assets
163 
118 
Union Electric Company |
Power
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
15 
 
Current regulatory assets
3 
 
Union Electric Company |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
21 
 
Union Electric Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
1 
 
Current regulatory assets
6 
 
Union Electric Company |
Uranium
 
 
Derivative [Line Items]
 
 
Current regulatory assets
2 
 
Union Electric Company |
Regulatory Liabilities Or Assets |
Power
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
12 1
19 
Union Electric Company |
Regulatory Liabilities Or Assets |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(29)2
2 
Union Electric Company |
Regulatory Liabilities Or Assets |
Natural Gas
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(11)3
(10)
Union Electric Company |
Regulatory Liabilities Or Assets |
Uranium
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(2)4
(6)
Ameren Illinois Company
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
84 
159 
Current regulatory assets
129 
38 
Ameren Illinois Company |
Power
 
 
Derivative [Line Items]
 
 
Current regulatory assets
11 
 
Ameren Illinois Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
1 
 
Current regulatory assets
31 
 
Ameren Illinois Company |
Regulatory Liabilities Or Assets |
Power
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(142)1
(108)
Ameren Illinois Company |
Regulatory Liabilities Or Assets |
Natural Gas
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
$ (43)3
$ (45)
Derivative Financial Instruments Derivative Financial Instruments (Offsetting Derivative Assets and Liabilities) (Details) (Commodity Contract, USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
$ 19 1
$ 34 1
Derivative Instruments
5 
10 
Net Amount
14 
24 
Gross Amounts Recognized in the Balance Sheet
232 1
178 1
Derivative Instruments
5 
10 
Cash Collateral Received/Posted
5 2
24 2
Net Amount
222 
144 
Union Electric Company
 
 
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
18 1
33 1
Derivative Instruments
5 
9 
Net Amount
13 
24 
Gross Amounts Recognized in the Balance Sheet
46 1
24 1
Derivative Instruments
5 
9 
Cash Collateral Received/Posted
5 2
9 2
Net Amount
36 
6 
Ameren Illinois Company
 
 
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
1 
1 
Derivative Instruments
 
1 
Net Amount
1 
 
Gross Amounts Recognized in the Balance Sheet
186 1
154 1
Derivative Instruments
 
1 
Cash Collateral Received/Posted
 
15 2
Net Amount
$ 186 
$ 138 
Derivative Financial Instruments (Maximum Exposure If Counterparties Fail To Perform On Contracts) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Concentration Risk [Line Items]
 
Maximum exposure to counterparties related to derivative contracts
$ 5 
Union Electric Company
 
Concentration Risk [Line Items]
 
Maximum exposure to counterparties related to derivative contracts
$ 5 
Derivative Financial Instruments (Potential Loss On Counterparty Exposures) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Concentration Risk [Line Items]
 
Potential loss on counterparty exposures related to derivative contracts
$ 5 
Union Electric Company
 
Concentration Risk [Line Items]
 
Potential loss on counterparty exposures related to derivative contracts
$ 5 
Derivative Financial Instruments (Cash Flow Hedges) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Derivative [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
$ 1,370 
$ 1,670 
$ 1,419 
$ 1,594 
$ 1,322 
$ 1,638 
$ 1,403 
$ 1,475 
$ 6,053 
$ 5,838 
$ 5,781 
Fair Value Measurements (Schedule of Valuation Process and Unobservable Inputs) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Discounted Cash Flow |
Minimum |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
5.00% 1 2
 
Counterparty credit risk
 
0.26% 3 4
Credit risk
0.43% 3 4
 
Discounted Cash Flow |
Minimum |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.43% 3 4
 
Credit risk
0.43% 3 4
 
Nodal basis
(0.40)1
 
Discounted Cash Flow |
Minimum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.26% 3 4
0.39% 3 4
Credit risk
0.43% 3 4
2.00% 3 4
Average bid/ask consensus peak and off-peak pricing
27 5
25 4
Estimated auction price for FTRs
(1,833)1
(1,594)1
Nodal basis
(6)1
(3)4
Discounted Cash Flow |
Minimum |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
35 1
34 1
Discounted Cash Flow |
Minimum |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
5.00% 1 2
 
Counterparty credit risk
 
0.26% 3 4
Credit risk
0.43% 3 4
 
Discounted Cash Flow |
Minimum |
Union Electric Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.57% 3 4
 
Credit risk
0.43% 3 4
 
Nodal basis
(0.10)1
 
Discounted Cash Flow |
Minimum |
Union Electric Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.26% 3 4
0.39% 3 4
Credit risk
0.43% 3 4
2.00% 3 4
Average bid/ask consensus peak and off-peak pricing
27 4
25 4
Estimated auction price for FTRs
(1,833)1
(1,594)1
Nodal basis
 
(3)4
Discounted Cash Flow |
Minimum |
Union Electric Company |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
35 1
34 1
Discounted Cash Flow |
Minimum |
Ameren Illinois Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.43% 3 4
 
Credit risk
0.43% 3 4
 
Nodal basis
(0.40)1
 
Discounted Cash Flow |
Minimum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Credit risk
0.43% 3 4
2.00% 3 4
Nodal basis
(6)1
(4)1
Average bid/ask consensus pricing
27 1
27 1
Discounted Cash Flow |
Maximum |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
5.00% 1 2
 
Counterparty credit risk
 
2.00% 3 4
Credit risk
0.43% 3 4
 
Discounted Cash Flow |
Maximum |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
13.00% 3 4
 
Credit risk
0.43% 3 4
 
Nodal basis
0.10 1
 
Discounted Cash Flow |
Maximum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.26% 3 4
0.50% 3 4
Credit risk
0.43% 3 4
2.00% 3 4
Average bid/ask consensus peak and off-peak pricing
50 5
51 4
Estimated auction price for FTRs
2,743 1
945 1
Nodal basis
0 1
(1)4
Discounted Cash Flow |
Maximum |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
40 1
41 1
Discounted Cash Flow |
Maximum |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
5.00% 1 2
 
Counterparty credit risk
 
2.00% 3 4
Credit risk
0.43% 3 4
 
Discounted Cash Flow |
Maximum |
Union Electric Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
13.00% 3 4
 
Credit risk
0.43% 3 4
 
Nodal basis
(0.10)1
 
Discounted Cash Flow |
Maximum |
Union Electric Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.26% 3 4
0.50% 3 4
Credit risk
0.43% 3 4
2.00% 3 4
Average bid/ask consensus peak and off-peak pricing
50 4
51 4
Estimated auction price for FTRs
2,743 1
945 1
Nodal basis
 
(1)4
Discounted Cash Flow |
Maximum |
Union Electric Company |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
40 1
41 1
Discounted Cash Flow |
Maximum |
Ameren Illinois Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
2.00% 3 4
 
Credit risk
0.43% 3 4
 
Nodal basis
0.10 1
 
Discounted Cash Flow |
Maximum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Credit risk
0.43% 3 4
2.00% 3 4
Nodal basis
0 1
0 1
Average bid/ask consensus pricing
38 1
36 1
Discounted Cash Flow |
Weighted Average |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
5.00% 1 2
 
Counterparty credit risk
 
1.00% 3 4
Credit risk
0.43% 3 4
 
Discounted Cash Flow |
Weighted Average |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
3.00% 3 4
 
Credit risk
0.43% 3 4
 
Nodal basis
(0.20)1
 
Discounted Cash Flow |
Weighted Average |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.26% 3 4
0.42% 3 4
Credit risk
0.43% 3 4
2.00% 3 4
Average bid/ask consensus peak and off-peak pricing
32 5
32 4
Estimated auction price for FTRs
171 1
305 1
Nodal basis
(2)1
(2)4
Discounted Cash Flow |
Weighted Average |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
36 1
36 1
Discounted Cash Flow |
Weighted Average |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
5.00% 1 2
 
Counterparty credit risk
 
1.00% 3 4
Credit risk
0.43% 3 4
 
Discounted Cash Flow |
Weighted Average |
Union Electric Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
5.00% 3 4
 
Credit risk
0.43% 3 4
 
Nodal basis
(0.10)1
 
Discounted Cash Flow |
Weighted Average |
Union Electric Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.26% 3 4
0.42% 3 4
Credit risk
0.43% 3 4
2.00% 3 4
Average bid/ask consensus peak and off-peak pricing
32 4
40 4
Estimated auction price for FTRs
171 1
305 1
Nodal basis
 
(2)4
Discounted Cash Flow |
Weighted Average |
Union Electric Company |
Uranium
 
 
Fair Value Inputs [Abstract]
 
 
Average bid/ask consensus pricing
36 1
36 1
Discounted Cash Flow |
Weighted Average |
Ameren Illinois Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.83% 3 4
 
Credit risk
0.43% 3 4
 
Nodal basis
(0.20)1
 
Discounted Cash Flow |
Weighted Average |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Credit risk
0.43% 3 4
2.00% 3 4
Nodal basis
(2)1
(2)1
Average bid/ask consensus pricing
32 1
30 1
Option Model |
Minimum |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
3.00% 4
10.00% 1
Option Model |
Minimum |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
31.00% 4
 
Nodal basis
(0.40)1
 
Option Model |
Minimum |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
3.00% 4
10.00% 1
Option Model |
Minimum |
Union Electric Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
31.00% 4
 
Nodal basis
(0.40)1
 
Option Model |
Minimum |
Ameren Illinois Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
50.00% 4
 
Nodal basis
(0.10)1
 
Option Model |
Maximum |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
39.00% 4
35.00% 1
Option Model |
Maximum |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
144.00% 4
 
Nodal basis
0 1
 
Option Model |
Maximum |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
39.00% 4
35.00% 1
Option Model |
Maximum |
Union Electric Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
144.00% 4
 
Nodal basis
0 1
 
Option Model |
Maximum |
Ameren Illinois Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
144.00% 4
 
Nodal basis
0 1
 
Option Model |
Weighted Average |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
32.00% 4
16.00% 1
Option Model |
Weighted Average |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
63.00% 4
 
Nodal basis
(0.20)1
 
Option Model |
Weighted Average |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
32.00% 4
16.00% 1
Option Model |
Weighted Average |
Union Electric Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
53.00% 4
 
Nodal basis
(0.30)1
 
Option Model |
Weighted Average |
Ameren Illinois Company |
Natural Gas
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
94.00% 4
 
Nodal basis
(0.10)1
 
Fundamental Energy Production Model |
Minimum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
0.00% 6
3.00% 1 7
Estimated future gas prices
4 1
4 1
Fundamental Energy Production Model |
Minimum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
0.00% 1 7
3.00% 1 7
Estimated future gas prices
4 1
4 1
Fundamental Energy Production Model |
Maximum |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
1.00% 6
4.00% 1 7
Estimated future gas prices
5 1
5 1
Fundamental Energy Production Model |
Maximum |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
1.00% 1 7
4.00% 1 7
Estimated future gas prices
5 1
5 1
Fundamental Energy Production Model |
Weighted Average |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
1.00% 1 7
4.00% 1 7
Estimated future gas prices
4 1
5 1
Fundamental Energy Production Model |
Weighted Average |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
1.00% 1 7
4.00% 1 7
Estimated future gas prices
4 1
5 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
$ (8)6
$ (3)6
Derivative liabilities |
Natural Gas
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
2 6
 
Derivative liabilities |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(144)6 8
(110)6 9
Derivative liabilities |
Uranium
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(2)6
(6)6
Derivative liabilities |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(8)6
(3)6
Derivative liabilities |
Union Electric Company |
Natural Gas
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(1)6
 
Derivative liabilities |
Union Electric Company |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(2)6 8
(2)6 9
Derivative liabilities |
Union Electric Company |
Uranium
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(2)6
(6)6
Derivative liabilities |
Ameren Illinois Company |
Natural Gas
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(1)6
 
Derivative liabilities |
Ameren Illinois Company |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(142)6 8
(108)6 9
Derivative assets |
Fuel Oils
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
2 6
8 6
Derivative assets |
Natural Gas
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
1 6
 
Derivative assets |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
11 6 8
21 6 9
Derivative assets |
Union Electric Company |
Fuel Oils
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
2 6
8 6
Derivative assets |
Union Electric Company |
Power
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
11 6 8
21 6 9
Derivative assets |
Ameren Illinois Company |
Natural Gas
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
$ 1 6
 
Fair Value Measurements (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Counterparty default risk liability valuation adjustment related to derivative contracts
$ 1 
$ 3 
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
$ 1 
$ 3 
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, 2014
Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
$ 547 1
$ 494 
Assets
566 2
528 2
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
365 
335 
Assets
365 2
336 2
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
182 
159 
Assets
187 2
163 2
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Assets
14 2
29 2
Cash And Cash Equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
3 
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
1 
3 
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
19 2
34 2
Derivative liabilities
232 2
178 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
Derivative liabilities
22 2
3 2
Commodity Contract |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 2
4 2
Derivative liabilities
54 2
56 2
Commodity Contract |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
14 2
29 2
Derivative liabilities
156 2
119 2
Commodity Contract |
Fuel Oils
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
2 2
9 2
Derivative liabilities
29 2
3 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
Derivative liabilities
21 2
 
Commodity Contract |
Fuel Oils |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
2 2
8 2
Derivative liabilities
8 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
56 2
57 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 liabilities
1 2
3 2
Commodity Contract |
Natural Gas |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
2 2
Derivative liabilities
53 2
54 2
Commodity Contract |
Natural Gas |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
 
Derivative liabilities
2 2
 
Commodity Contract |
Power
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 2
23 2
Derivative liabilities
145 2
112 2
Commodity Contract |
Power |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
4 2
2 2
Derivative liabilities
1 2
2 2
Commodity Contract |
Power |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
11 2
21 2
Derivative liabilities
144 2
110 2
Commodity Contract |
Uranium
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
2 2
6 2
Commodity Contract |
Uranium |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
2 2
6 2
Equity Securities |
U.S. Large Capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
364 
332 
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
364 
332 
Debt Securities |
Corporate Bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
63 
52 
Debt Securities |
Corporate Bonds |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
63 
52 
Debt Securities |
Municipal Bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
2 
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 
2 
Debt Securities |
U.S. treasury and agency securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
102 
94 
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
102 
94 
Debt Securities |
Asset-Backed Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
10 
10 
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 
10 
Debt Securities |
Other debt securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
5 
1 
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
5 
1 
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
547 1
494 
Assets
565 2
527 2
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
365 
335 
Assets
365 2
336 2
Union Electric Company |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
182 
159 
Assets
187 2
162 2
Union Electric Company |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Assets
13 2
29 2
Union Electric Company |
Cash And Cash Equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
3 
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
1 
3 
Union Electric Company |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
18 2
33 2
Derivative liabilities
46 2
24 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
Derivative liabilities
22 2
3 2
Union Electric Company |
Commodity Contract |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 2
3 2
Derivative liabilities
11 2
10 2
Union Electric Company |
Commodity Contract |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
13 2
29 2
Derivative liabilities
13 2
11 2
Union Electric Company |
Commodity Contract |
Fuel Oils
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
2 2
9 2
Derivative liabilities
29 2
3 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
Derivative liabilities
21 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
2 2
8 2
Derivative liabilities
8 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
12 2
11 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 liabilities
1 2
3 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
10 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 liabilities
1 2
 
Union Electric Company |
Commodity Contract |
Power
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 2
23 2
Derivative liabilities
3 2
4 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
4 2
2 2
Derivative liabilities
1 2
2 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
11 2
21 2
Derivative liabilities
2 2
2 2
Union Electric Company |
Commodity Contract |
Uranium
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
2 2
6 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
2 2
6 2
Union Electric Company |
Equity Securities |
U.S. Large Capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
364 
332 
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
364 
332 
Union Electric Company |
Debt Securities |
Corporate Bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
63 
52 
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
63 
52 
Union Electric Company |
Debt Securities |
Municipal Bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
2 
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 
2 
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
102 
94 
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
102 
94 
Union Electric Company |
Debt Securities |
Asset-Backed Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
10 
10 
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 
10 
Union Electric Company |
Debt Securities |
Other debt securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
5 
1 
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
5 
1 
Ameren Illinois Company |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 
1 
Derivative liabilities
186 2
154 2
Ameren Illinois Company |
Commodity Contract |
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
43 2
46 2
Ameren Illinois Company |
Commodity Contract |
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
143 2
108 2
Ameren Illinois Company |
Commodity Contract |
Natural Gas
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 1
Derivative liabilities
44 2
46 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 1
Derivative liabilities
43 2
46 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
1 2
 
Derivative liabilities
1 2
 
Ameren Illinois Company |
Commodity Contract |
Power
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
142 2
108 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
$ 142 2
$ 108 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, 2014
Dec. 31, 2013
Fuel Oils
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
$ 5 
$ 5 
Included in regulatory assets/liabilities
(9)
 
Purchases
 
3 
Sales
 
(1)
Settlements
(2)
(2)
Ending balance
(6)
5 
Change in unrealized gains (losses) related to assets/liabilities still held
(6)
 
Natural Gas
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
0 
0 
Included in regulatory assets/liabilities
1 
(1)
Purchases
(2)
1 
Sales
(1)
 
Settlements
1 
 
Ending balance
(1)
0 
Change in unrealized gains (losses) related to assets/liabilities still held
2 
 
Power
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(89)
(100)
Included in regulatory assets/liabilities
(53)
(15)
Purchases
34 
40 
Sales
(1)
 
Settlements
(24)
(15)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3
 
(3)
Transfers out of Level 3
 
4 
Ending balance
(133)
(89)
Change in unrealized gains (losses) related to assets/liabilities still held
(43)
(25)
Uranium
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(6)
(2)
Included in regulatory assets/liabilities
(1)
(3)
Purchases
 
(2)
Settlements
5 
1 
Ending balance
(2)
(6)
Change in unrealized gains (losses) related to assets/liabilities still held
(1)
(2)
Union Electric Company |
Fuel Oils
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
5 
5 
Included in regulatory assets/liabilities
(9)
 
Purchases
 
3 
Sales
 
(1)
Settlements
(2)
(2)
Ending balance
(6)
5 
Change in unrealized gains (losses) related to assets/liabilities still held
(6)
 
Union Electric Company |
Natural Gas
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
0 
0 
Purchases
 
0 
Sales
(1)
 
Ending balance
(1)
0 
Union Electric Company |
Power
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
19 
11 
Included in regulatory assets/liabilities
(14)
3 
Purchases
34 
40 
Sales
(1)
 
Settlements
(29)
(36)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3
 
(3)
Transfers out of Level 3
 
4 
Ending balance
9 
19 
Change in unrealized gains (losses) related to assets/liabilities still held
 
(1)
Union Electric Company |
Uranium
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(6)
(2)
Included in regulatory assets/liabilities
(1)
(3)
Purchases
 
(2)
Settlements
5 
1 
Ending balance
(2)
(6)
Change in unrealized gains (losses) related to assets/liabilities still held
(1)
(2)
Ameren Illinois Company |
Natural Gas
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
0 
0 
Included in regulatory assets/liabilities
1 
(1)
Purchases
(2)
1 
Settlements
1 
 
Ending balance
0 
0 
Change in unrealized gains (losses) related to assets/liabilities still held
2 
 
Ameren Illinois Company |
Power
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(108)
(111)
Included in regulatory assets/liabilities
(39)
(18)
Settlements
5 
21 
Ending balance
(142)
(108)
Change in unrealized gains (losses) related to assets/liabilities still held
$ (43)
$ (24)
Fair Value Measurements (Schedule Of Transfers Between Fair Value Hierarchy Levels) (Details) (Power, USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
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 
Union Electric Company
 
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 
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, 2014
Dec. 31, 2013
Carrying Amount
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term Debt and Capital Lease Obligations
$ 6,240 1
$ 6,038 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)
7,135 1
6,584 1
Preferred stock
122 1
118 1
Union Electric Company |
Carrying Amount
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term Debt and Capital Lease Obligations
3,999 
3,757 
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)
4,518 
4,124 
Preferred stock
73 
71 
Ameren Illinois Company |
Carrying Amount
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term Debt and Capital Lease Obligations
2,241 
1,856 
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)
2,517 
2,028 
Preferred stock
$ 49 
$ 47 
Nuclear Decommissioning Trust Fund Investments (Fair Values Of Investments In Debt And Equity Securities In Nuclear Decommissioning Trust Fund) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
$ 316 
$ 297 
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax
237 
203 
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax
4 
6 
Fair Value
549 
494 
Debt Securities
 
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
175 
157 
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax
7 
4 
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax
1 
2 
Fair Value
182 
159 
Equity Securities
 
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
138 
137 
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax
230 
199 
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax
4 
4 
Fair Value
364 
332 
Cash
 
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
1 
3 
Fair Value
1 
3 
Other Debt And Equity Securities
 
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
 
Cost
2 
1 
Fair Value
$ 2 
$ 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, 2014
Investments, Debt and Equity Securities [Abstract]
 
Cost, Less than 5 years
$ 98 
Cost, 5 years to 10 years
41 
Cost, Due after 10 years
36 
Cost, Total
175 
Fair Value, Less than 5 years
99 
Fair Value, 5 years to 10 years
42 
Fair Value, Due after 10 years
41 
Fair Value, Total
$ 182 
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 $)
Dec. 31, 2014
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
Less than 12 months, fair value
$ 34,000,000 
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss
1,000,000 
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss
3,000,000 
12 months or greater, fair value
13,000,000 
Total, fair value
47,000,000 
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss
4,000,000 
Debt Securities
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
Less than 12 months, fair value
28,000,000 
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss
1,000,000 
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss
1 
12 months or greater, fair value
8,000,000 
Total, fair value
36,000,000 
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss
1,000,000 
Equity Securities
 
Nuclear Decommissioning Trust Fund Investments [Line Items]
 
Less than 12 months, fair value
6,000,000 
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss
1,000,000 
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss
3,000,000 
12 months or greater, fair value
5,000,000 
Total, fair value
11,000,000 
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss
$ 4,000,000 
Callaway Energy Center (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
mill
Dec. 31, 2013
Dec. 31, 2012
Loss Contingencies [Line Items]
 
 
 
Nwf Fee Number Of Mills
1 
 
 
Annual decommissioning costs included in costs of service
 
$ 7 
$ 7 
Nuclear Plant
 
 
 
Loss Contingencies [Line Items]
 
 
 
Useful life
40 years 
 
 
Annual decommissioning costs included in costs of service
$ 7 
 
 
Retirement Benefits (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
bond
Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined Benefit Plan, Funded Status of Plan
$ 710 1
$ 461 1
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation, Change in Discount Rate
0.75% 
 
Number of high-quality corporate bonds
700 
 
Defined benefit plan, estimated future employer contributions during the next five years
290 
 
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, Funded Status of Plan
(616)1
(439)1
Assumptions used calculating net periodic benefit cost, expected long-term return on assets in future years
7.25% 
 
Postretirement Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined Benefit Plan, Funded Status of Plan
(94)1
(22)1
Assumptions used calculating net periodic benefit cost, expected long-term return on assets in future years
7.00% 
 
Minimum
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined benefit plan, estimated future employer contributions during the next five years
25 
 
Maximum
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Defined benefit plan, estimated future employer contributions during the next five years
115 
 
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
41.00% 
 
Ameren Illinois Company |
Pension Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Future funding requirement, percentage
40.00% 
 
Retirement Benefits (Summary Of Benefit Liability Recorded) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
 
 
Benefit liability recorded on the balance sheet
$ 710 1
$ 461 1
Union Electric Company
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Benefit liability recorded on the balance sheet
277 
191 
Ameren Illinois Company
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Benefit liability recorded on the balance sheet
$ 278 
$ 159 
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Change in plan assets:
 
 
 
Funded status – deficiency
$ (710)1
$ (461)1
 
Amounts recognized in the balance sheet consist of:
 
 
 
Noncurrent liability
705 
466 
 
Net liability recognized
710 1
461 1
 
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Accumulated benefit obligation at end of year
4,176 1
3,698 1
 
Change in benefit obligation:
 
 
 
Net benefit obligation at beginning of year
3,900 1
4,051 1
 
Service cost
79 1 2
91 1 2
81 2
Interest cost
183 1 2
163 1 2
166 2
Actuarial (gain) loss
462 1
(207)1
 
Benefits paid
(214)1
(198)1
 
Net benefit obligation at end of year
4,410 1
3,900 1
4,051 1
Change in plan assets:
 
 
 
Fair value of plan assets at beginning of year
3,461 1
3,127 1
 
Actual return on plan assets
448 1
376 1
 
Employer contributions
99 1
156 1
128 1
Benefits paid
(214)1
(198)1
 
Fair value of plan assets at end of year
3,794 1
3,461 1
3,127 1
Funded status – deficiency
616 1
439 1
 
Accrued benefit cost at December 31
616 1
439 1
 
Amounts recognized in the balance sheet consist of:
 
 
 
Current liability(f)
3 1 3
3 1 3
 
Noncurrent liability
613 1
436 1
 
Net liability recognized
616 1
439 1
 
Amounts recognized in regulatory assets consist of:
 
 
 
Net actuarial (gain) loss
452 1
282 1
 
Prior service cost (credit)
(6)1
(7)1
 
Amounts (pretax) recognized in accumulated OCI consist of:
 
 
 
Net actuarial (gain) loss
29 1
17 1
 
Prior service cost (credit)
 
0 1
 
Total
475 1
292 1
 
Postretirement Benefits
 
 
 
Change in benefit obligation:
 
 
 
Net benefit obligation at beginning of year
1,096 1
1,157 1
 
Service cost
19 1 2
22 1 2
22 2
Interest cost
50 1 2
46 1 2
47 2
Participant contributions
16 1
16 1
 
Actuarial (gain) loss
84 1
(76)1
 
Curtailment gain(c)
 
(3)2 4
 
Settlement
 
5 5
 
Benefits paid
(65)1
(64)1
 
Federal subsidy on benefits paid
3 1
3 1
 
Net benefit obligation at end of year
1,203 1
1,096 1
1,157 1
Change in plan assets:
 
 
 
Fair value of plan assets at beginning of year
1,074 1
938 1
 
Actual return on plan assets
75 1
156 1
 
Employer contributions
6 1
25 1
45 1
Federal subsidy on benefits paid
3 1
3 1
 
Participant contributions
16 1
16 1
 
Benefits paid
(65)1
(64)1
 
Fair value of plan assets at end of year
1,109 1
1,074 1
938 1
Funded status – deficiency
94 1
22 1
 
Accrued benefit cost at December 31
94 1
22 1
 
Amounts recognized in the balance sheet consist of:
 
 
 
Noncurrent asset
0 1 6
9 
 
Current liability(f)
2 1 3
1 1 3
 
Noncurrent liability
92 1
30 1
 
Net liability recognized
94 1
22 1
 
Amounts recognized in regulatory assets consist of:
 
 
 
Net actuarial (gain) loss
(7)1
(71)1
 
Prior service cost (credit)
(16)1
(20)1
 
Amounts (pretax) recognized in accumulated OCI consist of:
 
 
 
Net actuarial (gain) loss
(5)1
(12)1
 
Prior service cost (credit)
(1)1
(1)1
 
Total
$ (29)1
$ (104)1
 
Retirement Benefits (Assumptions Used To Determine Benefit Obligations) (Details)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Pension Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Discount rate at measurement date
4.00% 
4.75% 
Increase in future compensation
3.50% 
3.50% 
Postretirement Benefits
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
Discount rate at measurement date
4.00% 
4.75% 
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
$ 99 1
$ 156 1
$ 128 1
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
6 1
25 1
45 1
Union Electric Company |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
41 
60 
52 
Union Electric Company |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
3 
10 
9 
Ameren Illinois Company |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
39 
50 
46 
Ameren Illinois Company |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
2 
11 
35 
Other |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
19 
46 
30 
Other |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Cash contributions to benefit plans
$ 1 
$ 4 
$ 1 
Retirement Benefits (Target Allocation Of The Plans' Asset Categories) (Details)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
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
53.00% 
58.00% 
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
34.00% 
36.00% 
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
7.00% 
8.00% 
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
12.00% 
14.00% 
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
41.00% 
36.00% 
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% 1
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
60.00% 
63.00% 
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
40.00% 
41.00% 
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
7.00% 
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
13.00% 
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
36.00% 
33.00% 
Retirement Benefits (Fair Value Of Plan Assets Utilizing Fair Value Hierarchy) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Real estate
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Defined Benefit Plan, Purchases, Sales, and Settlements
$ 5 
$ 4 
 
Fair value of plan assets
147 
131 
118 
Private equity
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Defined Benefit Plan, Purchases, Sales, and Settlements
(3)
(6)
 
Fair value of plan assets
13 
15 
19 
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
3,794 1
3,461 1
3,127 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
411 
528 
 
Pension Benefits |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
3,327 
2,865 
 
Pension Benefits |
Significant Other Unobservable Inputs (Level 3)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
160 
146 
 
Pension Benefits |
Cash And Cash Equivalents
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
38 
44 
 
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
0 
5 
 
Pension Benefits |
Cash And Cash Equivalents |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
38 
39 
 
Pension Benefits |
U.S. large capitalization
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,331 
1,269 
 
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
0 
107 
 
Pension Benefits |
U.S. large capitalization |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,331 
1,162 
 
Pension Benefits |
U.S. small and mid-capitalization
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
270 
273 
 
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
270 
273 
 
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
494 
515 
 
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
134 
143 
 
Pension Benefits |
International and emerging markets |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
360 
372 
 
Pension Benefits |
Corporate Bonds
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,026 
860 
 
Pension Benefits |
Corporate Bonds |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,026 
860 
 
Pension Benefits |
Municipal Bonds
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
175 
149 
 
Pension Benefits |
Municipal Bonds |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
175 
149 
 
Pension Benefits |
U.S. treasury and agency securities
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
372 
256 
 
Pension Benefits |
U.S. treasury and agency securities |
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
6 
 
 
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
366 
256 
 
Pension Benefits |
Other
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
31 
27 
 
Pension Benefits |
Other |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
31 
27 
 
Pension Benefits |
Real estate
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
147 
131 
 
Pension Benefits |
Real estate |
Significant Other Unobservable Inputs (Level 3)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
147 
131 
 
Pension Benefits |
Private equity
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
13 
15 
 
Pension Benefits |
Private equity |
Significant Other Unobservable Inputs (Level 3)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
13 
15 
 
Pension Benefits |
Derivative assets
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1 
1 
 
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 
1 
 
Pension Benefits |
Derivative liabilities
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
 
(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)
 
Pension Benefits |
Medical benefit assets
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
(125)2
(112)2
 
Pension Benefits |
Net receivables
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
21 3
34 3
 
Pension Benefits |
Includes Medical Benefit Component Under Section401 H And Excludes Receivables Related To Pending Security Sales [Member]
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
3,898 
3,539 
 
Pension Benefits |
Excludes Medical Benefit Component Under Section401 H And Includes Receivables Related To Pending Security Sales [Member]
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
3,794 
3,461 
 
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,109 1
1,074 1
938 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
487 
490 
 
Postretirement Benefits |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
551 
511 
 
Postretirement Benefits |
Cash And Cash Equivalents
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
89 
77 
 
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
89 
77 
 
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
392 
398 
 
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
291 
297 
 
Postretirement Benefits |
U.S. large capitalization |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
101 
101 
 
Postretirement Benefits |
U.S. small and mid-capitalization
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
70 
77 
 
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
70 
77 
 
Postretirement Benefits |
International
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
131 
135 
 
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
37 
39 
 
Postretirement Benefits |
International |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
94 
96 
 
Postretirement Benefits |
Other Equity |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
7 
2 
 
Postretirement Benefits |
Corporate Bonds
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
105 
97 
 
Postretirement Benefits |
Corporate Bonds |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
105 
97 
 
Postretirement Benefits |
Municipal Bonds
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
111 
103 
 
Postretirement Benefits |
Municipal Bonds |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
111 
103 
 
Postretirement Benefits |
U.S. treasury and agency securities
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
89 
72 
 
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
89 
72 
 
Postretirement Benefits |
Other
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
44 
40 
 
Postretirement Benefits |
Other |
Significant Other Observable Inputs (Level 2)
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
44 
40 
 
Postretirement Benefits |
Medical benefit assets
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
125 2
112 2
 
Postretirement Benefits |
Net payables
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
(54)4
(39)4
 
Postretirement Benefits |
Excludes Medical Benefit Component Under Section401 H And Excludes Payables Related To Pending Security Sales [Member]
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
1,038 
1,001 
 
Postretirement Benefits |
Includes Medical Benefit Component Under Section401 H And Excludes Payables Related To Pending Security Sales [Member]
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Fair value of plan assets
$ 1,109 
$ 1,074 
 
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, 2014
Dec. 31, 2013
Real estate
 
 
Change in plan assets:
 
 
Fair value of plan assets at beginning of year
$ 131 
$ 118 
Actual Return on Plan Assets Related to Assets Still Held at the Reporting Date
11 
9 
Purchases, Sales and Settlements, net
5 
4 
Fair value of plan assets at end of year
147 
131 
Private equity
 
 
Change in plan assets:
 
 
Fair value of plan assets at beginning of year
15 
19 
Actual Return on Plan Assets Related to Assets Still Held at the Reporting Date
(9)
(9)
Actual Return on Plan Assets Related to Assets Sold During the Period
10 
11 
Purchases, Sales and Settlements, net
(3)
(6)
Fair value of plan assets at end of year
$ 13 
$ 15 
Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Service cost
$ 79 1 2
$ 91 1 2
$ 81 1
Interest cost
183 1 2
163 1 2
166 1
Expected return on plan assets
(229)1
(218)1
(208)1
Prior service credit
(1)1
(2)1
(3)1
Actuarial (gain) loss
49 1
87 1
75 1
Curtailment
 
(12)1
 
Net periodic benefit cost (benefit)
81 1
109 1 3
111 1 4
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Service cost
19 1 2
22 1 2
22 1
Interest cost
50 1 2
46 1 2
47 1
Expected return on plan assets
(65)1
(62)1
(56)1
Transition obligation
 
 
2 1
Prior service credit
(5)1
(6)1
(6)1
Actuarial (gain) loss
(7)1
8 1
5 1
Curtailment
 
(7)1
 
Net periodic benefit cost (benefit)
(8)1
1 1 3
14 1 4
New Ameren Energy Resources Company, LLC |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost (benefit)
6 1 3
9 1 3
 
New Ameren Energy Resources Company, LLC |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost (benefit)
$ 7 1 3
 
 
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, 2014
Pension Benefits
 
Defined Benefit Plan Disclosure [Line Items]
 
Prior service credit
$ (1)1
Net actuarial loss
86 1
Net actuarial (gain) loss
2 1
Net periodic benefit cost
87 1
Postretirement Benefits
 
Defined Benefit Plan Disclosure [Line Items]
 
Prior service credit
(4)1
Net actuarial loss
15 1
Net actuarial (gain) loss
(2)1
Net periodic benefit cost
$ 9 1
Retirement Benefits (Summary Of Benefit Plan Costs Incurred) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
$ 81 1
$ 109 1 2
$ 111 1 3
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
(8)1
1 1 2
14 1 3
Union Electric Company |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
50 
69 
63 
Union Electric Company |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
3 
8 
10 
Ameren Illinois Company |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
30 
41 
37 
Ameren Illinois Company |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
(9)
0 
4 
Other |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
1 
5 
2 
Other |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
(2)
 
0 
Parent Company |
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
81 4
115 4
102 4
Parent Company |
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Net periodic benefit cost
$ (8)4
$ 8 4
$ 14 4
Retirement Benefits (Schedule Of Expected Payments From Qualified Trust And Company Funds) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Pension Benefits |
Paid From Qualified Trust
 
Defined Benefit Plan Disclosure [Line Items]
 
2015
$ 253 
2016
256 
2017
257 
2018
260 
2019
260 
2020 - 2024
1,273 
Pension Benefits |
Paid From Company Funds
 
Defined Benefit Plan Disclosure [Line Items]
 
2015
3 
2016
3 
2017
4 
2018
3 
2019
3 
2020 - 2024
11 
Postretirement Benefits |
Paid From Qualified Trust
 
Defined Benefit Plan Disclosure [Line Items]
 
2015
58 
2016
61 
2017
64 
2018
68 
2019
70 
2020 - 2024
388 
Postretirement Benefits |
Paid From Company Funds
 
Defined Benefit Plan Disclosure [Line Items]
 
2015
2 
2016
2 
2017
2 
2018
2 
2019
2 
2020 - 2024
$ 11 
Retirement Benefits (Assumptions Used To Determine Net Periodic Benefit Cost) (Details)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Pension Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Discount rate at measurement date
4.75% 
4.00% 
4.50% 
Expected return on plan assets
7.25% 
7.50% 
7.75% 
Increase in future compensation
3.50% 
3.50% 
3.50% 
Postretirement Benefits
 
 
 
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Discount rate at measurement date
4.75% 
4.00% 
4.50% 
Expected return on plan assets
7.00% 
7.25% 
7.50% 
Increase in future compensation
3.50% 
3.50% 
3.50% 
Medical cost trend rate (initial)
5.00% 
5.00% 
5.50% 
Medical cost trend rate (ultimate)
5.00% 
5.00% 
5.00% 
Years to ultimate rate
 
 
1 year 
Retirement Benefits (Schedule Of Potential Changes In Key Assumptions) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Pension Benefits
 
Defined Benefit Plan Disclosure [Line Items]
 
Service Cost and Interest Cost, .25% decrease in discount rate
$ (1)
Benefit Obligation, .25% decrease in discount rate
138 
Service Cost and Interest Cost, .25% increase in salary rate
2 
Benefit Obligation, .25% increase in salary rate
13 
Postretirement Benefits
 
Defined Benefit Plan Disclosure [Line Items]
 
Service Cost and Interest Cost, .25% decrease in discount rate
1 
Benefit Obligation, .25% decrease in discount rate
39 
Service Cost and Interest Cost, 1.00% increase in annual medical trend
3 
Benefit Obligation, 1.00% increase in annual medical trend
36 
Service Cost and Interest Cost, 1.00% decrease in annual medical trend
(2)
Benefit Obligation, 1.00% decrease in annual medical trend
$ (33)
Retirement Benefits (Schedule Of Matching Contributions) (Details) (401 (K), USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
 
 
 
Employer contributions
$ 28 1
$ 27 1
$ 26 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
11 
10 
9 
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Apr. 30, 2014
Performance Share Units
Dec. 31, 2014
Performance Share Units
Dec. 31, 2013
Performance Share Units
Dec. 31, 2012
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
 
 
 
 
 
 
 
Maximum shares available for grants
8,000,000 
 
 
 
 
 
 
Share-based compensation expense
$ 19 
$ 20 
$ 22 
 
 
 
 
Employee service share-based compensation, tax benefit from compensation expense
7 
8 
8 
 
 
 
 
Amounts paid to settle share units
33 
11 
11 
 
 
 
 
Compensation cost not yet recognized
$ 18 
 
 
 
 
 
 
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
 
 
 
$ 50.34 1
$ 38.90 2
$ 31.19 
 
Closing common share price
 
 
 
 
 
$ 36.16 
$ 30.72 
Three-year risk-free rate
 
 
 
 
0.78% 
0.36% 
 
Volatility rate, minimum
 
 
 
12.00% 
12.00% 
12.00% 
 
Volatility rate, maximum
 
 
 
18.00% 
18.00% 
21.00% 
 
Stock-Based Compensation (Summary Of Nonvested Shares) (Details) (Performance Share Units, USD $)
1 Months Ended 12 Months Ended
Apr. 30, 2014
Dec. 31, 2014
Dec. 31, 2013
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
 
1,218,544 
 
Share Units, Granted
38,559 1
688,323 2
 
Share Units, Unearned or forfeited
 
(97,432)3
 
Share Units, Earned and vested
 
(685,617)4
 
Share Units, Nonvested at end of year
 
1,162,377 
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
 
$ 33.23 
 
Weighted-averageFair Value per Unit, granted
$ 50.34 1
$ 38.90 2
$ 31.19 
Weighted-average Fair Value per Unit, Unearned or forfeited
 
$ 34.42 3
 
Weighted-average Fair Value per Unit, Earned and vested
 
$ 36.12 4
 
Weighted-average Fair Value per Unit, Nonvested at end of year
 
$ 35.35 
$ 33.23 
Three-year risk-free rate
 
0.78% 
0.36% 
Volatility rate, minimum
12.00% 
12.00% 
12.00% 
Volatility rate, maximum
18.00% 
18.00% 
21.00% 
Maximum
 
 
 
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
 
 
 
Three-year risk-free rate
0.79% 
 
 
Minimum
 
 
 
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
 
 
 
Three-year risk-free rate
0.76% 
 
 
Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Income Taxes [Line Items]
 
 
 
Statutory federal income tax rate:
35.00% 
35.00% 
35.00% 
Depreciation differences
 
 
(1.00%)
Amortization of investment tax credit
(1.00%)
(1.00%)
(1.00%)
State tax
4.00% 
4.00% 
5.00% 
Other permanent items
1.00% 
0.00% 
(1.00%)
Effective income tax rate
39.00% 
38.00% 
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%)
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
0.00% 
1.00% 
0.00% 
Effective income tax rate
37.00% 
38.00% 
37.00% 
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% 
0.00% 
(1.00%)
State tax
6.00% 
6.00% 
6.00% 
Effective income tax rate
41.00% 
40.00% 
40.00% 
Income Taxes (Schedule Of Components Of Income Tax Expense (Benefit)) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Income Taxes [Line Items]
 
 
 
Current Federal taxes
$ (37)
$ (118)
$ 40 
Current State taxes
(37)
19 
10 
Deferred Federal taxes
369 
368 
204 
Deferred State taxes
88 
48 
60 
Deferred investment tax credits, amortization
(6)
(6)
(7)
Total income tax expense
377 
311 
307 
Union Electric Company
 
 
 
Income Taxes [Line Items]
 
 
 
Current Federal taxes
(13)
136 
(25)
Current State taxes
(3)
41 
(10)
Deferred Federal taxes
222 
64 
248 
Deferred State taxes
28 
6 
44 
Deferred investment tax credits, amortization
(5)
(5)
(5)
Total income tax expense
229 
242 
252 
Ameren Illinois Company
 
 
 
Income Taxes [Line Items]
 
 
 
Current Federal taxes
(51)
(15)
(7)
Current State taxes
(2)
21 
(3)
Deferred Federal taxes
159 
99 
76 
Deferred State taxes
38 
6 
30 
Deferred investment tax credits, amortization
(1)
(1)
(2)
Total income tax expense
143 
110 
94 
Other
 
 
 
Income Taxes [Line Items]
 
 
 
Current Federal taxes
27 1
(239)1
72 
Current State taxes
(32)1
(43)1
23 
Deferred Federal taxes
(12)1
205 1
(120)
Deferred State taxes
22 1
36 1
(14)
Deferred investment tax credits, amortization
0 
0 
0 
Total income tax expense
$ 5 
$ (41)
$ (39)
Income Taxes (Schedule Of Deferred Tax Assets And Liabilities Resulting From Temporary Differences) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Income Taxes [Line Items]
 
 
Plant related
$ 4,185 
$ 3,769 
Regulatory assets, net
78 
76 
Deferred benefit costs
(220)
(273)
Revenue Requirement Reconciliation Adjustment
69 
 
Revenue requirement reconciliation adjustments
 
(2)
ARO
(675)
(541)
Other
134 
115 
Total net accumulated deferred income tax liabilities
3,571 1
3,144 2
Current assets
352 
106 
Union Electric Company
 
 
Income Taxes [Line Items]
 
 
Plant related
2,776 
2,513 
Regulatory assets, net
82 
74 
Deferred benefit costs
(80)
(74)
ARO
(107)
(76)
Other
86 
67 
Total net accumulated deferred income tax liabilities
2,757 1
2,504 2
Current assets
49 
20 
Ameren Illinois Company
 
 
Income Taxes [Line Items]
 
 
Plant related
1,393 
1,243 
Regulatory assets, net
 
2 
Regulatory assets, net
(5)
 
Deferred benefit costs
(45)
(85)
Revenue Requirement Reconciliation Adjustment
66 
 
Revenue requirement reconciliation adjustments
 
(4)
ARO
(139)
(95)
Other
 
10 
Deferred Tax Assets, Other
(22)
 
Total net accumulated deferred income tax liabilities
1,248 1
1,071 2
Current assets
160 
45 
Other
 
 
Income Taxes [Line Items]
 
 
Plant related
16 
13 
Regulatory assets, net
1 
 
Deferred benefit costs
(95)
(114)
Revenue Requirement Reconciliation Adjustment
3 
2 
ARO
(429)
(370)
Other
70 
38 
Total net accumulated deferred income tax liabilities
$ (434)1
$ (431)2
Income Taxes (Schedule Of Net Operating Loss Carryforwards And Tax Credit Carryforwards) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
$ 531 
$ 408 
Tax credit carryforwards
131 
118 
Tax credit carryforward, expiration period start
Jan. 01, 2013 
Jan. 01, 2013 
Change in valuation allowance
3 
3 
Deferred Tax Assets, Charitable Contribution Carryforwards
19 1
18 1
Deferred Tax Assets, Valuation Allowance, Noncurrent
6 2
(3)3
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent
13 
15 
Federal
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
457 4
360 5
Tax credit carryforwards
99 6
88 6
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
74 7
48 8
Tax credit carryforwards
36 9
34 9
Tax Credit Carryforward, Valuation Allowance
(4)10
4 11
Net operating loss carryforward, expiration period start
Jan. 01, 2020 
Jan. 01, 2019 
Tax credit carryforward, expiration period start
Jan. 01, 2013 
Jan. 01, 2013 
Change in valuation allowance
1 
2 
Union Electric Company
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
86 
64 
Tax credit carryforwards
21 
12 
Union Electric Company |
Federal
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
75 4
61 5
Tax credit carryforwards
21 6
12 6
Union Electric Company |
State
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
11 7
3 8
Tax credit carryforwards
1 9
1 9
Tax Credit Carryforward, Valuation Allowance
(1)10
(1)11
Ameren Illinois Company
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
137 
95 
Tax credit carryforwards
2 
 
Ameren Illinois Company |
Federal
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
127 4
84 5
Tax credit carryforwards
1 6
0 6
Ameren Illinois Company |
State
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
10 7
11 8
Tax credit carryforwards
2 9
1 9
Tax Credit Carryforward, Valuation Allowance
(1)10
(1)11
Other
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
308 
249 
Tax credit carryforwards
108 
106 
Deferred Tax Assets, Charitable Contribution Carryforwards
19 1
18 1
Deferred Tax Assets, Valuation Allowance, Noncurrent
6 2
(3)3
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent
13 
15 
Other |
Federal
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
255 4
215 5
Tax credit carryforwards
77 6
76 6
Other |
State
 
 
Operating Loss Carryforwards [Line Items]
 
 
Net operating loss carryforwards
53 7
34 8
Tax credit carryforwards
33 9
32 9
Tax Credit Carryforward, Valuation Allowance
$ (2)10
$ (2)11
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Income Tax Contingency [Line Items]
 
 
 
Liability for interest
$ 1 
$ 6 
$ 5 
Interest charges (income)
(1)
(5)
1 
Liability for interest
0 
1 
6 
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities
20 
0 
 
Union Electric Company
 
 
 
Income Tax Contingency [Line Items]
 
 
 
Liability for interest
0 
8 
6 
Interest charges (income)
0 
(8)
2 
Liability for interest
0 
0 
8 
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities
18 
0 
 
Ameren Illinois Company
 
 
 
Income Tax Contingency [Line Items]
 
 
 
Liability for interest
 
1 
1 
Interest charges (income)
 
(1)
0 
Liability for interest
0 
0 
1 
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities
 
0 
 
Other
 
 
 
Income Tax Contingency [Line Items]
 
 
 
Liability for interest
1 
(3)
(2)
Interest charges (income)
(1)
4 
(1)
Liability for interest
0 
1 
(3)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities
 
0 
 
2007 through 2011 tax year |
Union Electric Company
 
 
 
Income Tax Contingency [Line Items]
 
 
 
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities
$ 13 
 
 
Income Taxes (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended 1 Months Ended 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Jan. 31, 2011
Maximum
Illinois Corporate Income Tax
Dec. 31, 2014
Union Electric Company
Dec. 31, 2013
Union Electric Company
Dec. 31, 2012
Union Electric Company
Dec. 31, 2014
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2012
Ameren Illinois Company
Dec. 31, 2014
Income Tax Rate in 2015
Illinois Corporate Income Tax
Dec. 31, 2014
Income Tax Rate in 2025
Illinois Corporate Income Tax
Dec. 31, 2014
State
Income Taxes [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities
$ 20 
$ 0 
 
 
$ 18 
$ 0 
 
 
$ 0 
 
 
 
$ 2 
State corporate income tax rate
4.00% 
4.00% 
5.00% 
9.50% 
3.00% 
3.00% 
3.00% 
6.00% 
6.00% 
6.00% 
7.75% 
7.30% 
 
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Union Electric Company
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
$ 27 
$ 25 
$ 20 
Operating Expenses
124 
116 
106 
Union Electric Company |
Ameren Missouri Power Supply Agreements with Ameren Illinois
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
5 
3 
1 1
Union Electric Company |
Ameren Missouri and Ameren Illinois Rent and Facility Services
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
21 
21 
19 
Union Electric Company |
Ameren Missouri and Ameren Illinois miscellaneous support services
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
1 
1 
1 
Union Electric Company |
Ameren Services Support Services Agreement
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
124 
116 
106 
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
1 1
Ameren Illinois Company
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
2 
4 
1 
Operating Expenses
109 
93 
88 
Ameren Illinois Company |
Ameren Missouri and Ameren Illinois Rent and Facility Services
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
2 
1 
1 
Ameren Illinois Company |
Ameren Missouri and Ameren Illinois miscellaneous support services
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Revenues
1 
3 
1 1
Ameren Illinois Company |
Ameren Illinois Power Supply Agreements with Ameren Missouri
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
5 
1 1
 
Ameren Illinois Company |
Ameren Illinois transmission agreements with ATXI
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
2 
2 
3 
Ameren Illinois Company |
Purchased Power
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
7 
5 
3 
Ameren Illinois Company |
Ameren Services Support Services Agreement
 
 
 
Related Party Transaction [Line Items]
 
 
 
Operating Expenses
109 
93 
88 
Ameren Illinois Company |
Money Pool
 
 
 
Related Party Transaction [Line Items]
 
 
 
Interest (Charges) Income
$ 1 1
$ 1 1
$ 0 1
Related Party Transactions (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
1 Months Ended 12 Months Ended
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
Dec. 31, 2014
Ameren Illinois Power Supply Agreements with Ameren Missouri
Ameren Illinois 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 
168,400 
Long-term Contract for Purchase of Electric Power, Related Party Contract, Fixed Power, Rate
 
28 
 
37 
 
29 
51 
Commitments And Contingencies (Callaway Nuclear Energy Center) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Commitments and Contingencies [Line Items]
 
Threshold Amount For Retrospective Insurance Assessment For Covered Loss Under Public Liability And Nuclear Worker Liability Insurance Policy
$ 375,000,000 
Insurance aggregate maximum coverage
13,616,000,000 1
Insurance maximum coverage per incident
128,000,000 
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 
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
1 year 
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
1 year 4 months 10 days 
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
900,000.0 
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
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
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 
Non-radiation event [Member]
 
Commitments and Contingencies [Line Items]
 
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period
$ 1,830,000,000 
Commitments And Contingencies (Schedule Of Lease Obligations) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Commitments and Contingencies [Line Items]
 
 
 
Capital lease payments, due in one year
$ 33 1 2
 
 
Capital lease payments, due in two years
33 1 2
 
 
Capital lease payments, due in three years
33 1 2
 
 
Capital lease payments, due in four years
32 1 2
 
 
Capital lease payments, due in five years
32 1 2
 
 
Capital lease payments, After 5 Years
360 1 2
 
 
Capital lease payments, Total
523 1 2
 
 
Less Amount representing interest, due in one year
27 1
 
 
Less Amount representing interest, due in two years
27 1
 
 
Less Amount representing interest, due in three years
27 1
 
 
Less Amount representing interest, due in four years
26 1
 
 
Less Amount representing interest, due in 5 years
25 1
 
 
Less Amount representing interest, After 5 Years
97 1
 
 
Less Amount representing interest, Total
229 1
 
 
Present value of minimum capital lease payments, due in one year
6 1
 
 
Present value of minimum capital lease payments, due in two years
6 1
 
 
Present value of minimum capital lease payments, due in three years
6 1
 
 
Present value of minimum capital lease payments, due in four years
6 1
 
 
Present value of minimum capital lease payments, due in five years
7 1
 
 
Present value of minimum capital lease payments, After 5 Years
263 1
 
 
Present value of minimum capital lease payments, Total
294 1
 
 
Operating leases, due in one year
13 1 3
 
 
Operating leases, due in two years
12 1 3
 
 
Operating leases, due in three years
12 1 3
 
 
Operating leases, due in four years
12 1 3
 
 
Operating leases, due in five years
11 1 3
 
 
Operating leases, After 5 Years
38 1 3
 
 
Operating leases, Total
98 1 3
 
 
Total lease obligations, due in one year
19 1
 
 
Total lease obligations, due in two years
18 1
 
 
Total lease obligations, due in three years
18 1
 
 
Total lease obligations, due in four years
18 1
 
 
Total lease obligations, due in five years
18 1
 
 
Total lease obligations, After 5 Years
301 1
 
 
Total lease obligations, Total
392 1
 
 
Annual obligation for real estate leases and railroad licenses
2 
 
 
Total rental expense
37 4
32 4
33 4
Union Electric Company
 
 
 
Commitments and Contingencies [Line Items]
 
 
 
Capital lease payments, due in one year
33 2
 
 
Capital lease payments, due in two years
33 2
 
 
Capital lease payments, due in three years
33 2
 
 
Capital lease payments, due in four years
32 2
 
 
Capital lease payments, due in five years
32 2
 
 
Capital lease payments, After 5 Years
360 2
 
 
Capital lease payments, Total
523 2
 
 
Less Amount representing interest, due in one year
27 
 
 
Less Amount representing interest, due in two years
27 
 
 
Less Amount representing interest, due in three years
27 
 
 
Less Amount representing interest, due in four years
26 
 
 
Less Amount representing interest, due in 5 years
25 
 
 
Less Amount representing interest, After 5 Years
97 
 
 
Less Amount representing interest, Total
229 
 
 
Present value of minimum capital lease payments, due in one year
6 
 
 
Present value of minimum capital lease payments, due in two years
6 
 
 
Present value of minimum capital lease payments, due in three years
6 
 
 
Present value of minimum capital lease payments, due in four years
6 
 
 
Present value of minimum capital lease payments, due in five years
7 
 
 
Present value of minimum capital lease payments, After 5 Years
263 
 
 
Present value of minimum capital lease payments, Total
294 
 
 
Operating leases, due in one year
11 3
 
 
Operating leases, due in two years
11 3
 
 
Operating leases, due in three years
11 3
 
 
Operating leases, due in four years
10 3
 
 
Operating leases, due in five years
10 3
 
 
Operating leases, After 5 Years
37 3
 
 
Operating leases, Total
90 3
 
 
Total lease obligations, due in one year
17 
 
 
Total lease obligations, due in two years
17 
 
 
Total lease obligations, due in three years
17 
 
 
Total lease obligations, due in four years
16 
 
 
Total lease obligations, due in five years
17 
 
 
Total lease obligations, After 5 Years
300 
 
 
Total lease obligations, Total
384 
 
 
Annual obligation for real estate leases and railroad licenses
1 
 
 
Total rental expense
32 
29 
29 
Ameren Illinois Company
 
 
 
Commitments and Contingencies [Line Items]
 
 
 
Operating leases, due in one year
1 3
 
 
Operating leases, due in two years
1 3
 
 
Operating leases, due in three years
1 3
 
 
Operating leases, due in four years
1 3
 
 
Operating leases, due in five years
1 3
 
 
Operating leases, After 5 Years
1 3
 
 
Operating leases, Total
6 3
 
 
Annual obligation for real estate leases and railroad licenses
1 
 
 
Total rental expense
$ 25 
$ 21 
$ 19 
Commitments And Contingencies (Schedule Of Estimated Purchased Power Commitments) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
$ 1,317 1
2015
1,029 1
2016
949 1
2017
357 1
2018
303 1
Thereafter
1,231 1
Total
5,186 1
Coal
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
654 1
2015
659 1
2016
682 1
2017
111 1
2018
114 1
Thereafter
0 1
Total
2,220 1
Natural Gas
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
222 1 2
2015
125 1 2
2016
85 1 2
2017
53 1 2
2018
32 1 2
Thereafter
71 1 2
Total
588 1 2
Nuclear Fuel
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
53 1
2015
60 1
2016
59 1
2017
82 1
2018
42 1
Thereafter
138 1
Total
434 1
Purchased Power
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
190 1 3
2015
104 1 3
2016
66 1 3
2017
55 1 3
2018
56 1 3
Thereafter
596 1 3
Total
1,067 1 3
Methane Gas
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
3 1
2015
3 1
2016
4 1
2017
5 1
2018
5 1
Thereafter
76 1
Total
96 1
Other
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
195 1
2015
78 1
2016
53 1
2017
51 1
2018
54 1
Thereafter
350 1
Total
781 1
Union Electric Company
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
898 
2015
804 
2016
809 
2017
257 
2018
219 
Thereafter
525 
Total
3,512 
Union Electric Company |
Coal
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
654 
2015
659 
2016
682 
2017
111 
2018
114 
Thereafter
0 
Total
2,220 
Union Electric Company |
Natural Gas
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
39 2
2015
22 2
2016
17 2
2017
11 2
2018
10 2
Thereafter
22 2
Total
121 2
Union Electric Company |
Nuclear Fuel
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
53 
2015
60 
2016
59 
2017
82 
2018
42 
Thereafter
138 
Total
434 
Union Electric Company |
Purchased Power
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
21 
2015
21 
2016
21 
2017
21 
2018
21 
Thereafter
106 
Total
211 
Union Electric Company |
Methane Gas
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
3 
2015
3 
2016
4 
2017
5 
2018
5 
Thereafter
76 
Total
96 
Union Electric Company |
Other
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
128 
2015
39 
2016
26 
2017
27 
2018
27 
Thereafter
183 
Total
430 
Ameren Illinois Company
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
381 
2015
210 
2016
137 
2017
100 
2018
84 
Thereafter
706 
Total
1,618 
Ameren Illinois Company |
Natural Gas
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
183 2
2015
103 2
2016
68 2
2017
42 2
2018
22 2
Thereafter
49 2
Total
467 2
Ameren Illinois Company |
Purchased Power
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
169 3
2015
83 3
2016
45 3
2017
34 3
2018
35 3
Thereafter
490 3
Total
856 3
Ameren Illinois Company |
Other
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2014
29 
2015
24 
2016
24 
2017
24 
2018
27 
Thereafter
167 
Total
295 
Investment in Energy Efficiency Programs |
Union Electric Company
 
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
 
2015
$ 71 
Commitments And Contingencies (Environmental Matters) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
EPA Clean Power Plan CO2 Proposed Reductions
30.00% 
Estimated Environmental Expenditures to Comply with Clean Power Plan
$ 2,000,000,000 
Manufactured Gas Plant
 
Accrual for environmental loss contingencies
250,000,000 
Manufactured Gas Plant |
Ameren Illinois Company
 
Number of remediation sites
44 
Loss contingency range of possible loss, minimum
250,000,000 
Loss contingency range of possible loss, maximum
314,000,000 
Accrual for environmental loss contingencies
250,000,000 
Former Coal Ash Landfill |
Ameren Illinois Company
 
Loss contingency range of possible loss, minimum
500,000 
Loss contingency range of possible loss, maximum
6,000,000 
Accrual for environmental loss contingencies
500,000 
Other Environmental |
Ameren Illinois Company
 
Accrual for environmental loss contingencies
700,000 
Former Coal Tar Distillery |
Union Electric Company
 
Loss contingency range of possible loss, minimum
2,000,000 
Loss contingency range of possible loss, maximum
5,000,000 
Accrual for environmental loss contingencies
2,000,000 
Sauget Area 2 |
Union Electric Company
 
Loss contingency range of possible loss, minimum
1,000,000 
Loss contingency range of possible loss, maximum
2,500,000 
Accrual for environmental loss contingencies
1,000,000 
Substation in St Charles, Missouri |
Union Electric Company
 
Loss contingency range of possible loss, minimum
1,600,000 
Loss contingency range of possible loss, maximum
4,500,000 
Accrual for environmental loss contingencies
1,600,000 
Minimum
 
Estimated capital costs to comply with existing and known federal and state air emissions regulations
350,000,000 
Maximum
 
Estimated capital costs to comply with existing and known federal and state air emissions regulations
$ 400,000,000 
Commitments And Contingencies (Pumped-Storage Hydroelectric Facility Breach) (Details) (Union Electric Company, USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Union Electric Company
 
Commitments and Contingencies [Line Items]
 
Litigation Settlement, Amount
$ 27 
Insurance Settlements Receivable
$ 41 
Divestiture Transactions and Discontinued Operations (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
9 Months Ended 12 Months Ended 1 Months Ended 3 Months Ended 12 Months Ended 3 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2014
Shutdown Of Meredosia And Hutsonville Energy Centers [Member]
Dec. 31, 2013
Shutdown Of Meredosia And Hutsonville Energy Centers [Member]
Sep. 30, 2014
New Ameren Energy Resources Company, LLC
Dec. 31, 2012
New Ameren Energy Resources Company, LLC
Dec. 31, 2014
New Ameren Energy Resources Company, LLC
Mar. 14, 2013
New Ameren Energy Resources Company, LLC
Dec. 31, 2014
Notes Payable, Other Payables
New Ameren Energy Resources Company, LLC
Dec. 31, 2013
Notes Payable, Other Payables
New Ameren Energy Resources Company, LLC
Jan. 31, 2014
Elgin, Gibson City and Grand Tower Energy Centers
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, 2014
Ameren Energy Marketing Company
Dec. 31, 2014
Guarantee Type, Other [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceeds from Sales of Business, Affiliate and Productive Assets
 
 
 
 
 
 
 
 
 
 
$ 168.0 
$ 137.5 
 
 
 
 
 
Proceeds from Asset Sale Held in Escrow
 
 
 
 
 
 
 
 
 
 
17 
 
 
 
 
 
 
Impairment of assets to be disposed of
 
 
 
 
 
2,580 
 
 
 
 
 
 
201 
1,950 
628 
 
 
Working Capital and Contingent Liability Payment
 
 
 
 
13 
 
 
 
 
 
 
 
 
 
 
 
 
Discontinued operations deferred tax expense
 
 
 
 
 
 
 
 
 
 
 
 
99 
 
 
 
 
Discontinued operations deferred tax benefit
 
 
 
 
 
 
 
 
 
 
 
 
86 
 
 
 
 
Disposal group, fair value
 
 
 
 
 
 
 
 
 
 
 
137.5 
 
 
 
 
 
Asset retirement obligations
396 
369 
32 
31 
 
 
 
 
 
 
 
 
 
 
 
 
 
Loss contingency range of possible loss, maximum
 
 
 
 
 
 
29.0 
 
 
 
 
 
 
 
 
 
 
Notes, Loans and Financing Receivable, Net, Noncurrent
 
 
 
 
 
 
 
 
12 
18 
 
 
 
 
 
 
 
Collateral to be posted if credit ratings are below investment grade
 
 
 
 
 
 
26 
 
 
 
 
 
 
 
 
 
 
Guarantees, Maximum Exposure
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
11 
7 
Buyer's indemnification guarantee obligation
 
 
 
 
 
 
 
25 
 
 
 
 
 
 
 
 
 
Loss Contingency Accrual
 
 
 
 
 
 
29 
 
 
 
 
 
 
 
 
 
 
Guarantees Outstanding
 
 
 
 
 
 
114 
 
 
 
 
 
 
 
 
106 
8 
Letters of Credit Outstanding, Amount
 
 
 
 
 
 
$ 9 
 
 
 
 
 
 
 
 
 
 
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, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2012
New Ameren Energy Resources Company, LLC
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 
$ 1,037 
$ 1,047 
 
 
 
 
Operating expenses
(2)
(1,207)1
(3,474)2
 
 
 
 
Operating income (loss)
(1)
(170)
(2,427)
 
 
 
 
Other income (loss)
0 
(1)
0 
 
 
 
 
Interest charges
0 
(39)
(56)
 
 
 
 
Income (loss) before income taxes
(1)
(210)
(2,483)
 
 
 
 
Income tax (expense) benefit
0 
(13)
987 
 
 
 
 
Income (Loss) from Discontinued Operations, Net of Tax (Note 16)
(1)
(223)
(1,496)
 
 
 
 
Impairment of assets to be disposed of
 
 
 
$ 2,580 
$ 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, 2014
Dec. 31, 2013
Dec. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
 
Asset retirement obligations
$ 396 
$ 369 
 
Assets of discontinued operations
 
 
 
Accounts receivable and unbilled revenue
0 
5 
 
Materials and supplies
0 
5 
 
Property and plant, net
0 
142 
 
Accumulated deferred income taxes, net
15 1
13 1
 
Total assets of discontinued operations
15 
165 
1,611 
Liabilities of discontinued operations
 
 
 
Accounts payable and other current obligations
1 
5 
 
Asset retirement obligations
32 2
40 2
 
Total liabilities of discontinued operations
33 
45 
 
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
$ 32 
$ 31 
 
Segment Information (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
segment
Dec. 31, 2013
Dec. 31, 2012
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Number of reportable segments
 
 
 
 
 
 
 
 
2 
 
 
External revenues
$ 1,370 
$ 1,670 
$ 1,419 
$ 1,594 
$ 1,322 
$ 1,638 
$ 1,403 
$ 1,475 
$ 6,053 
$ 5,838 
$ 5,781 
Depreciation and amortization
 
 
 
 
 
 
 
 
745 
706 
673 
Interest Expense
 
 
 
 
 
 
 
 
341 
398 
392 
Income taxes (benefit)
 
 
 
 
 
 
 
 
377 
311 
307 
Net income (loss) attributable to Ameren Corporation
48 
293 
149 
96 
37 
302 
95 
(145)
586 
289 
(974)
Capital expenditures
 
 
 
 
 
 
 
 
1,785 
1,379 
1,063 
Total assets
22,676 
 
 
 
21,042 
 
 
 
22,676 
21,042 
 
Assets of discontinued operations (Note 16)
15 
 
 
 
165 
 
 
 
15 
165 
1,611 
Income (Loss) from Continuing Operations Attributable to Parent
46 
294 
150 
97 
48 
305 
105 
54 
587 
512 
516 
Union Electric Company
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
 
 
 
 
 
 
 
 
3,526 
3,516 
3,252 
Revenue from Related Parties
 
 
 
 
 
 
 
 
27 
25 
20 
Depreciation and amortization
 
 
 
 
 
 
 
 
473 
454 
440 
Interest and dividend income
 
 
 
 
 
 
 
 
28 
27 
32 
Interest Expense
 
 
 
 
 
 
 
 
211 
210 
223 
Income taxes (benefit)
 
 
 
 
 
 
 
 
229 
242 
252 
Net income (loss) attributable to Ameren Corporation
 
 
 
 
 
 
 
 
390 
395 
416 
Capital expenditures
 
 
 
 
 
 
 
 
747 
648 
595 
Total assets
13,541 
 
 
 
12,904 
 
 
 
13,541 
12,904 
13,043 
Ameren Illinois Company
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
 
 
 
 
 
 
 
 
2,496 
2,307 
2,524 
Revenue from Related Parties
 
 
 
 
 
 
 
 
2 
4 
1 
Depreciation and amortization
 
 
 
 
 
 
 
 
263 
243 
221 
Interest and dividend income
 
 
 
 
 
 
 
 
7 
2 
0 
Interest Expense
 
 
 
 
 
 
 
 
112 
143 
129 
Income taxes (benefit)
 
 
 
 
 
 
 
 
143 
110 
94 
Net income (loss) attributable to Ameren Corporation
 
 
 
 
 
 
 
 
201 
160 
141 
Capital expenditures
 
 
 
 
 
 
 
 
835 
701 
442 
Total assets
8,381 
 
 
 
7,454 
 
 
 
8,381 
7,454 
7,282 
Other Segment
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
 
 
 
 
 
 
 
 
31 
15 
5 
Revenue from Related Parties
 
 
 
 
 
 
 
 
2 
2 
3 
Depreciation and amortization
 
 
 
 
 
 
 
 
9 
9 
12 
Interest and dividend income
 
 
 
 
 
 
 
 
2 
1 
 
Interest Expense
 
 
 
 
 
 
 
 
18 
45 
40 
Income taxes (benefit)
 
 
 
 
 
 
 
 
5 
(41)
(39)
Net income (loss) attributable to Ameren Corporation
 
 
 
 
 
 
 
 
(4)
(43)
(41)
Capital expenditures
 
 
 
 
 
 
 
 
203 1
30 1
26 1
Total assets
942 
 
 
 
752 
 
 
 
942 
752 
1,228 
Intersegment Elimination
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Revenue from Related Parties
 
 
 
 
 
 
 
 
(31)
(31)
(24)
Total assets
(203)
 
 
 
(233)
 
 
 
(203)
(233)
(934)
Segment, Continuing Operations
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
 
 
 
 
 
 
 
 
6,053 
5,838 
5,781 
Depreciation and amortization
 
 
 
 
 
 
 
 
745 
706 
673 
Interest and dividend income
 
 
 
 
 
 
 
 
37 
30 
32 
Interest Expense
 
 
 
 
 
 
 
 
341 
398 
392 
Income taxes (benefit)
 
 
 
 
 
 
 
 
377 
311 
307 
Capital expenditures
 
 
 
 
 
 
 
 
1,785 
1,379 
1,063 
Total assets
22,661 2
 
 
 
20,877 2
 
 
 
22,661 2
20,877 2
20,619 2
Union Electric Company
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
739 
1,097 
900 
817 
763 
1,093 
889 
796 
3,553 
3,541 
3,272 
Revenue from Related Parties
 
 
 
 
 
 
 
 
27 
25 
20 
Depreciation and amortization
 
 
 
 
 
 
 
 
473 
454 
440 
Interest Expense
 
 
 
 
 
 
 
 
211 
210 
223 
Income taxes (benefit)
 
 
 
 
 
 
 
 
229 
242 
252 
Net income (loss) attributable to Ameren Corporation
(5)
223 
127 
48 
33 
239 
85 
41 
393 
398 
419 
Capital expenditures
 
 
 
 
 
 
 
 
747 
648 
595 
Total assets
13,541 
 
 
 
12,904 
 
 
 
13,541 
12,904 
 
Ameren Illinois Company
 
 
 
 
 
 
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
External revenues
633 
572 
519 
774 
564 
547 
516 
684 
2,498 
2,311 
2,525 
Revenue from Related Parties
 
 
 
 
 
 
 
 
2 
4 
1 
Depreciation and amortization
 
 
 
 
 
 
 
 
263 
243 
221 
Interest Expense
 
 
 
 
 
 
 
 
112 
143 
129 
Income taxes (benefit)
 
 
 
 
 
 
 
 
143 
110 
94 
Net income (loss) attributable to Ameren Corporation
46 
75 
29 
54 
22 
77 
32 
32 
204 
163 
144 
Capital expenditures
 
 
 
 
 
 
 
 
835 
701 
442 
Total assets
$ 8,381 
 
 
 
$ 7,454 
 
 
 
$ 8,381 
$ 7,454 
 
Selected Quarterly Information (Summary Of Selected Quarterly Information) (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Selected Quarterly Financial Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
$ 1,370 
$ 1,670 
$ 1,419 
$ 1,594 
$ 1,322 
$ 1,638 
$ 1,403 
$ 1,475 
$ 6,053 
$ 5,838 
$ 5,781 
Operating Income
125 
561 
322 
246 
171 
567 
261 
185 
1,254 
1,184 
1,188 
Net income (loss)
49 
295 
150 
98 
38 
304 
96 
(143)
592 
295 
(974)
Net income attributable to Ameren Corporation - continuing operations
46 
294 
150 
97 
48 
305 
105 
54 
587 
512 
516 
Net Income (Loss) Attributable to Ameren Corporation - Discontinued Operations
2 
(1)
(1)
(1)
(11)
(3)
(10)
(199)
(1)
(223)
(1,490)
Net income (loss) attributable to Ameren Corporation
48 
293 
149 
96 
37 
302 
95 
(145)
586 
289 
(974)
Earnings per common share - basic - continuing operations
$ 0.19 
$ 1.21 
$ 0.62 
$ 0.40 
$ 0.19 
$ 1.26 
$ 0.44 
$ 0.22 
$ 2.42 
$ 2.11 
$ 2.13 
Earnings (loss) per common share - basic - discontinued operations
$ 0.01 
 
$ (0.01)
$ 0.00 
$ (0.04)
$ (0.01)
$ (0.05)
$ (0.82)
$ 0.00 
$ (0.92)
$ (6.14)
Earnings (loss) per common share - basic
$ 0.20 
$ 1.21 
$ 0.61 
$ 0.40 
$ 0.15 
$ 1.25 
$ 0.39 
$ (0.60)
$ 2.42 
$ 1.19 
$ (4.01)
Earnings per common share - diluted - continuing operations
$ 0.19 
$ 1.20 
$ 0.62 
$ 0.40 
$ 0.19 
$ 1.25 
$ 0.44 
$ 0.22 
$ 2.40 
$ 2.10 
$ 2.13 
Earnings (loss) per common share - diluted - discontinued operations
$ 0.01 
$ 0.00 
$ (0.01)
$ 0.00 
$ (0.04)
$ (0.01)
$ (0.05)
$ (0.82)
$ 0.00 
$ (0.92)
$ (6.14)
Earnings (loss) per common share - diluted
$ 0.20 
$ 1.20 
$ 0.61 
$ 0.40 
$ 0.15 
$ 1.24 
$ 0.39 
$ (0.60)
$ 2.40 
$ 1.18 
$ (4.01)
Union Electric Company
 
 
 
 
 
 
 
 
 
 
 
Selected Quarterly Financial Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
739 
1,097 
900 
817 
763 
1,093 
889 
796 
3,553 
3,541 
3,272 
Operating Income
29 
394 
243 
119 
96 
417 
179 
111 
785 
803 
845 
Net income (loss)
 
 
 
 
 
 
 
 
393 
398 
419 
Net income (loss) attributable to Ameren Corporation
(5)
223 
127 
48 
33 
239 
85 
41 
393 
398 
419 
Net Income Available to Common Stockholder
(5)
222 
126 
47 
33 
238 
84 
40 
390 
395 
416 
Ameren Illinois Company
 
 
 
 
 
 
 
 
 
 
 
Selected Quarterly Financial Information [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
633 
572 
519 
774 
564 
547 
516 
684 
2,498 
2,311 
2,525 
Operating Income
97 
158 
75 
120 
85 
158 
87 
85 
450 
415 
377 
Net income (loss)
 
 
 
 
 
 
 
 
204 
163 
144 
Net income (loss) attributable to Ameren Corporation
46 
75 
29 
54 
22 
77 
32 
32 
204 
163 
144 
Net Income Available to Common Stockholder
$ 45 
$ 75 
$ 28 
$ 53 
$ 21 
$ 77 
$ 31 
$ 31 
$ 201 
$ 160 
$ 141 
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, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating revenues
$ 1,370 
$ 1,670 
$ 1,419 
$ 1,594 
$ 1,322 
$ 1,638 
$ 1,403 
$ 1,475 
$ 6,053 
$ 5,838 
$ 5,781 
Operating expenses
 
 
 
 
 
 
 
 
4,799 
4,654 
4,593 
Operating Income
125 
561 
322 
246 
171 
567 
261 
185 
1,254 
1,184 
1,188 
Interest income from affiliates
 
 
 
 
 
 
 
 
10 1 2
3 1
4 1 3
Other Nonoperating Income (Expense)
 
 
 
 
 
 
 
 
57 
43 
33 
Interest charges
 
 
 
 
 
 
 
 
341 
398 
392 
Income taxes (benefit)
 
 
 
 
 
 
 
 
377 
311 
307 
Net income attributable to Ameren Corporation - continuing operations
46 
294 
150 
97 
48 
305 
105 
54 
587 
512 
516 
Net Income (Loss) Attributable to Ameren Corporation - Discontinued Operations
2 
(1)
(1)
(1)
(11)
(3)
(10)
(199)
(1)
(223)
(1,490)
Net income (loss) attributable to Ameren Corporation
48 
293 
149 
96 
37 
302 
95 
(145)
586 
289 
(974)
Comprehensive Income from Continuing Operations
 
 
 
 
 
 
 
 
 
 
 
Pension and other postretirement activity, net of income taxes (benefit)
 
 
 
 
 
 
 
 
(12)
30 
(8)
Comprehensive Income (Loss) from Continuing Operations, Net of Tax, Portion Attributable to Parent
 
 
 
 
 
 
 
 
575 
542 
508 
Other Comprehensive Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
 
 
 
 
 
 
 
 
 
(18)
58 
Comprehensive Income (Loss) from Discontinued Operations
 
 
 
 
 
 
 
 
(1)
(242)
(1,440)
Comprehensive Income (Loss) Attributable to Ameren Corporation
 
 
 
 
 
 
 
 
574 
300 
(932)
Other Comprehensive Income (Loss), Taxes:
 
 
 
 
 
 
 
 
 
 
 
Pension and other postretirement activity, tax (benefit)
 
 
 
 
 
 
 
 
(7)
16 
(6)
Parent Company
 
 
 
 
 
 
 
 
 
 
 
Condensed Financial Statements, Captions [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Operating expenses
 
 
 
 
 
 
 
 
11 
26 
17 
Operating Income
 
 
 
 
 
 
 
 
(11)
(26)
(17)
Equity in earnings of subsidiaries
 
 
 
 
 
 
 
 
607 
546 
546 
Interest income from affiliates
 
 
 
 
 
 
 
 
3 
3 
3 
Other Nonoperating Income (Expense)
 
 
 
 
 
 
 
 
2 
(5)
(4)
Interest charges
 
 
 
 
 
 
 
 
16 
42 
39 
Income taxes (benefit)
 
 
 
 
 
 
 
 
(2)
(36)
(27)
Net income attributable to Ameren Corporation - continuing operations
 
 
 
 
 
 
 
 
587 
512 
516 
Net Income (Loss) Attributable to Ameren Corporation - Discontinued Operations
 
 
 
 
 
 
 
 
(1)
(223)
(1,490)
Net income (loss) attributable to Ameren Corporation
 
 
 
 
 
 
 
 
586 
289 
(974)
Comprehensive Income from Continuing Operations
 
 
 
 
 
 
 
 
 
 
 
Pension and other postretirement activity, net of income taxes (benefit)
 
 
 
 
 
 
 
 
(12)
30 
(8)
Comprehensive Income (Loss) from Continuing Operations, Net of Tax, Portion Attributable to Parent
 
 
 
 
 
 
 
 
575 
542 
508 
Other Comprehensive Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
 
 
 
 
 
 
 
 
0 
(19)
50 
Comprehensive Income (Loss) from Discontinued Operations
 
 
 
 
 
 
 
 
(1)
(242)
(1,440)
Comprehensive Income (Loss) Attributable to Ameren Corporation
 
 
 
 
 
 
 
 
574 
300 
(932)
Other Comprehensive Income (Loss), Taxes:
 
 
 
 
 
 
 
 
 
 
 
Pension and other postretirement activity, tax (benefit)
 
 
 
 
 
 
 
 
$ (7)
$ 16 
$ (6)
Schedule I - Condensed Financial Information Of Parent (Balance Sheet) (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
ASSETS
 
 
 
 
Cash and cash equivalents
$ 5 
$ 30 
$ 184 
 
Miscellaneous accounts and notes receivable
81 
196 
 
 
Current accumulated deferred income taxes, net
352 
106 
 
 
Other current assets
86 
85 
 
 
Total current assets
2,046 
1,972 
 
 
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent
13 
15 
 
 
Other non-current assets
664 
720 
 
 
TOTAL ASSETS
22,676 
21,042 
 
 
LIABILITIES AND EQUITY
 
 
 
 
Current maturities of long-term debt
120 
534 
 
 
Short-term debt
714 
368 
 
 
Accounts Payable and Accrued Liabilities, Current
711 
806 
 
 
Other current liabilities
434 
351 
 
 
Total current liabilities
2,249 
2,461 
 
 
Other deferred credits and liabilities
514 
538 
 
 
Commitments and Contingencies
   
   
 
 
Retained earnings
1,103 
907 
 
 
Accumulated other comprehensive income (loss)
(9)
3 
 
 
Total equity
6,855 
6,686 
6,767 
 
TOTAL LIABILITIES AND EQUITY
22,676 
21,042 
 
 
Parent Company
 
 
 
 
ASSETS
 
 
 
 
Cash and cash equivalents
1 
11 
23 
3 
Advances to money pool
55 
334 
 
 
Accounts receivable - affiliates
28 
18 
 
 
Notes Receivable, Related Parties, Current
94 
9 
 
 
Miscellaneous accounts and notes receivable
39 
125 
 
 
Current accumulated deferred income taxes, net
143 
41 
 
 
Other current assets
14 
1 
 
 
Total current assets
374 
539 
 
 
Investments in subsidiaries - continuing operations
6,680 
6,336 
 
 
Investments in subsidiaries - discontinued operations
(4)
(5)
 
 
Note receivable - affiliates
100 
51 
 
 
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent
264 
570 
 
 
Other non-current assets
152 
141 
 
 
TOTAL ASSETS
7,566 
7,632 
 
 
LIABILITIES AND EQUITY
 
 
 
 
Current maturities of long-term debt
0 
425 
 
 
Short-term debt
585 
368 
 
 
Accounts Payable and Accrued Liabilities, Current
0 
119 
 
 
Accounts payable – affiliates
88 
4 
 
 
Other current liabilities
52 
20 
 
 
Total current liabilities
725 
936 
 
 
Other deferred credits and liabilities
128 
152 
 
 
Total liabilities
853 
1,088 
 
 
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
5,617 
5,632 
 
 
Retained earnings
1,103 
907 
 
 
Accumulated other comprehensive income (loss)
(9)
3 
 
 
Total equity
6,713 
6,544 
 
 
TOTAL LIABILITIES AND EQUITY
$ 7,566 
$ 7,632 
 
 
Schedule I - Condensed Financial Information Of Parent (Statement of Cash Flows) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
 
 
 
Net cash provided by operating activities
$ 1,551 
$ 1,693 
$ 1,690 
Cash Flows From Investing Activities:
 
 
 
Proceeds from Collection of Notes Receivable
95 
6 
 
Contributions to Note Receivable
(89)
(5)
 
Other
11 
1 
20 
Net Cash Provided by (Used in) Investing Activities
(1,717)
(1,723)
(1,310)
Cash flows from financing activities:
 
 
 
Dividends on common stock
(390)
(388)
(382)
Short-term debt and credit facility borrowings, net
346 
368 
(148)
Repayments of Other Long-term Debt
(697)
(399)
(760)
Net cash provided by (used in) financing activities
141 
(149)
(426)
Net change in cash and cash equivalents
(25)
(179)
(46)
Cash and cash equivalents at beginning of year
30 
184 
 
Cash and cash equivalents at end of year
5 
30 
184 
Noncash financing activity – dividends on common stock
 
 
7 
Parent Company
 
 
 
Condensed Financial Statements, Captions [Line Items]
 
 
 
Net cash provided by operating activities
514 
453 
532 
Cash Flows From Investing Activities:
 
 
 
Money pool advances, net
279 
(371)
24 
Intercompany notes receivable, net
(134)
(23)
(20)
Investments in subsidiaries
(280)
(50)
(2)
Return of investments
215 
1 
21 
Proceeds from Collection of Notes Receivable
95 
6 
0 
Contributions to Note Receivable
(89)
(5)
0 
Other
(12)
(3)
(5)
Net Cash Provided by (Used in) Investing Activities
74 
(445)
18 
Cash flows from financing activities:
 
 
 
Dividends on common stock
(390)
(388)
(382)
Short-term debt and credit facility borrowings, net
217 
368 
(148)
Repayments of Other Long-term Debt
(425)
0 
0 
Net cash provided by (used in) financing activities
(598)
(20)
(530)
Net change in cash and cash equivalents
(10)
(12)
20 
Cash and cash equivalents at beginning of year
11 
23 
3 
Cash and cash equivalents at end of year
1 
11 
23 
Cash dividends received from consolidated subsidiaries
340 
570 
610 
Noncash investing activity - divestiture
 
494 
0 
Noncash Investing activity- investment in subsidiaries
(19)
0 
0 
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 9 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2014
Parent Company
Dec. 31, 2013
Parent Company
Dec. 31, 2012
Parent Company
Dec. 31, 2013
Parent Company
Merchant Generation
Dec. 31, 2012
Parent Company
Merchant Generation
Sep. 30, 2014
New Ameren Energy Resources Company, LLC
May 31, 2014
Senior Unsecured Notes8875 Due2014 [Member]
Parent Company
Dec. 31, 2014
Senior Unsecured Notes8875 Due2014 [Member]
Parent Company
Impairment and Other Charges [Line Items]
 
 
 
 
 
 
 
 
 
 
 
Unrecognized Tax Benefit Recorded In Other Deferred Credits And Liabilities
$ 52 
$ 84 
 
$ 53 
$ 53 
 
 
 
 
 
 
Repayments of Other Long-term Debt
697 
399 
760 
425 
0 
0 
 
 
 
425 
 
Long-term debt interest rate
 
 
 
 
 
 
 
 
 
8.875% 
8.875% 
Impairment charge on long-lived assets and related charges
 
 
 
 
 
 
201 
1,880 
 
 
 
Working Capital and Contingent Liability Payment
 
 
 
 
 
 
 
 
$ 13 
 
 
Schedule II - Valuation And Qualifying Accounts (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended 12 Months Ended
Dec. 31, 2014
Allowance For Doubtful Accounts
Dec. 31, 2013
Allowance For Doubtful Accounts
Dec. 31, 2012
Allowance For Doubtful Accounts
Dec. 31, 2014
Valuation Allowance of Deferred Tax Assets
Dec. 31, 2013
Valuation Allowance of Deferred Tax Assets
Dec. 31, 2012
Valuation Allowance of Deferred Tax Assets
Dec. 31, 2014
Union Electric Company
Allowance For Doubtful Accounts
Dec. 31, 2013
Union Electric Company
Allowance For Doubtful Accounts
Dec. 31, 2012
Union Electric Company
Allowance For Doubtful Accounts
Dec. 31, 2014
Union Electric Company
Valuation Allowance of Deferred Tax Assets
Dec. 31, 2013
Union Electric Company
Valuation Allowance of Deferred Tax Assets
Dec. 31, 2012
Union Electric Company
Valuation Allowance of Deferred Tax Assets
Dec. 31, 2011
Union Electric Company
Valuation Allowance of Deferred Tax Assets
Dec. 31, 2014
Ameren Illinois Company
Allowance For Doubtful Accounts
Dec. 31, 2013
Ameren Illinois Company
Allowance For Doubtful Accounts
Dec. 31, 2012
Ameren Illinois Company
Allowance For Doubtful Accounts
Dec. 31, 2012
Ameren Illinois Company
Valuation Allowance of Deferred Tax Assets
Dec. 31, 2014
Ameren Illinois Company
Valuation Allowance of Deferred Tax Assets
Dec. 31, 2013
Ameren Illinois Company
Valuation Allowance of Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Balance at Beginning of Period
$ 18 
$ 17 
$ 20 
$ 7 
$ 2 
$ 1 
$ 5 
$ 5 
$ 7 
$ 1 
$ 1 
$ 1 
$ 1 
$ 13 
$ 12 
$ 13 
 
$ 1 
$ 1 
Charged to Costs and Expenses
36 
35 
30 
3 
5 
1 
16 
16 
11 
 
 
 
 
20 
19 
19 
1 
 
 
Charged to Other Accounts
4 1
4 1
2 1
 
 
 
 
 
 
 
 
 
 
4 1
4 1
2 1
 
 
 
Deductions
37 2
38 2
35 2
 
 
 
13 2
16 2
13 2
 
 
 
 
24 2
22 2
22 2
 
 
 
Balance at End of Period
$ 21 
$ 18 
$ 17 
$ 10 
$ 7 
$ 2 
$ 8 
$ 5 
$ 5 
$ 1 
$ 1 
$ 1 
$ 1 
$ 13 
$ 13 
$ 12 
$ 1 
$ 1 
$ 1