UNION ELECTRIC CO, 10-Q filed on 5/12/2014
Quarterly Report
Document and Entity Information
3 Months Ended
Mar. 31, 2014
Apr. 30, 2014
Entity Information [Line Items]
 
 
Document Type
10-Q 
 
Amendment Flag
false 
 
Document Period End Date
Mar. 31, 2014 
 
Document Fiscal Year Focus
2014 
 
Document Fiscal Period Focus
Q1 
 
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 
Union Electric Company
 
 
Entity Information [Line Items]
 
 
Document Type
10-Q 
 
Amendment Flag
false 
 
Document Period End Date
Mar. 31, 2014 
 
Document Fiscal Year Focus
2014 
 
Document Fiscal Period Focus
Q1 
 
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 
Ameren Illinois Company
 
 
Entity Information [Line Items]
 
 
Document Type
10-Q 
 
Amendment Flag
false 
 
Document Period End Date
Mar. 31, 2014 
 
Document Fiscal Year Focus
2014 
 
Document Fiscal Period Focus
Q1 
 
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 
Consolidated Statement of Income (Loss) (USD $)
In Millions, except Per Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Operating Revenues:
 
 
Electric
$ 1,106 
$ 1,088 
Gas
488 
387 
Total operating revenues
1,594 
1,475 
Operating Expenses:
 
 
Fuel
204 
213 
Purchased power
112 
151 
Gas purchased for resale
304 
230 
Other operations and maintenance
420 
399 
Depreciation and amortization
181 
175 
Taxes other than income taxes
127 
122 
Total operating expenses
1,348 
1,290 
Operating Income
246 
185 
Other Income and Expenses:
 
 
Miscellaneous income
18 1
15 1
Miscellaneous expense
9 1
8 1
Total other income (expense)
9 
7 
Interest Charges
92 
101 
Income Before Income Taxes
163 
91 
Income Taxes
64 
35 
Income from Continuing Operations
99 
56 
Loss from Discontinued Operations, Net of Taxes (Note 12)
(1)
(199)
Net Income (Loss)
98 
(143)
Comprehensive Income (Loss)
96 
(152)
Less: Net Income (Loss) Attributable to Noncontrolling Interests:
 
 
Net Income from Continuing Operations Attributable to Noncontrolling Interests
2 
2 
Net Income (Loss):
 
 
Continuing Operations
97 
54 
Discontinued Operations
(1)
(199)
Net Income (Loss)
96 
(145)
Income (Loss) from Continuing Operations, Per Basic Share
$ 0.40 
$ 0.22 
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share
$ 0.00 
$ (0.82)
Earnings Per Share, Basic
$ 0.40 
$ (0.60)
Dividends per Common Share
$ 0.40 
$ 0.40 
Average Common Shares Outstanding - Basic
242.6 
242.6 
Union Electric Company
 
 
Operating Revenues:
 
 
Electric
749 
732 
Gas
68 
64 
Total operating revenues
817 
796 
Operating Expenses:
 
 
Fuel
204 
213 
Purchased power
33 
26 
Gas purchased for resale
40 
37 
Other operations and maintenance
227 
221 
Depreciation and amortization
116 
111 
Taxes other than income taxes
78 
77 
Total operating expenses
698 
685 
Operating Income
119 
111 
Other Income and Expenses:
 
 
Miscellaneous income
14 
14 
Miscellaneous expense
4 
5 
Total other income (expense)
10 
9 
Interest Charges
52 
60 
Income Before Income Taxes
77 
60 
Income Taxes
29 
19 
Net Income (Loss)
48 
41 
Other Comprehensive Income
0 
0 
Comprehensive Income (Loss)
48 
41 
Net Income (Loss):
 
 
Net Income (Loss)
48 
41 
Preferred Stock Dividends
1 
1 
Net Income Available to Common Stockholder
47 
40 
Ameren Illinois Company
 
 
Operating Revenues:
 
 
Electric
353 
360 
Gas
421 
324 
Total operating revenues
774 
684 
Operating Expenses:
 
 
Purchased power
81 
127 
Gas purchased for resale
264 
193 
Other operations and maintenance
200 
176 
Depreciation and amortization
63 
61 
Taxes other than income taxes
46 
42 
Total operating expenses
654 
599 
Operating Income
120 
85 
Other Income and Expenses:
 
 
Miscellaneous income
3 
1 
Miscellaneous expense
4 
3 
Total other income (expense)
(1)
(2)
Interest Charges
30 
31 
Income Before Income Taxes
89 
52 
Income Taxes
35 
20 
Net Income (Loss)
54 
32 
Pension and other postretirement benefit plan activity, net of income taxes (benefit)
(1)
(1)
Comprehensive Income (Loss)
53 
31 
Net Income (Loss):
 
 
Net Income (Loss)
54 
32 
Preferred Stock Dividends
1 
1 
Net Income Available to Common Stockholder
$ 53 
$ 31 
Consolidated Statement of Income (Loss) (Parenthetical) (Ameren Illinois Company, USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Ameren Illinois Company
 
 
Pension and other postretirement benefit plan activity, tax expense (benefit)
$ (1)
$ (1)
Consolidated Statement of Comprehensive Income (Loss) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Income from Continuing Operations
$ 99 
$ 56 
Other Comprehensive Income, Net of Taxes
 
 
Other Comprehensive Income, Net of Taxes
0 
0 
Comprehensive Income from Continuing Operations
99 
56 
Less: Comprehensive Income from Continuing Operations Attributable to Noncontrolling Interests
2 
2 
Comprehensive Income from Continuing Operations Attributable to Ameren Corporation
97 
54 
Loss from Discontinued Operations, Net of Taxes
(1)
(199)
Other Comprehensive Loss from Discontinued Operations, Net of Taxes
0 
(7)
Comprehensive Loss from Discontinued Operations Attributable to Ameren Corporation
(1)
(206)
Comprehensive Income (Loss)
$ 96 
$ (152)
Consolidated Balance Sheet (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Current Assets:
 
 
Cash and cash equivalents
$ 26 
$ 30 
Accounts receivable - trade (less allowance for doubtful accounts)
553 
404 
Unbilled revenue
236 
304 
Miscellaneous accounts and notes receivable
201 
196 
Materials and supplies
424 
526 
Current regulatory assets
220 
156 
Current accumulated deferred income taxes, net
95 
106 
Other current assets
70 
85 
Assets of discontinued operations (Note 12)
15 
165 
Total current assets
1,840 
1,972 
Property and Plant, Net
16,425 
16,205 
Investments and Other Assets:
 
 
Nuclear decommissioning trust fund
503 
494 
Goodwill
411 
411 
Intangible assets
17 
22 
Regulatory assets
1,251 
1,240 
Other assets
719 
698 
Total investments and other assets
2,901 
2,865 
TOTAL ASSETS
21,166 
21,042 
Current Liabilities:
 
 
Current maturities of long-term debt
648 
534 
Short-term Debt
700 
368 
Accounts and wages payable
559 
806 
Taxes accrued
89 
55 
Interest accrued
104 
86 
Current regulatory liabilities
248 
216 
Other current liabilities
344 
351 
Liabilities of discontinued operations (Note 12)
33 
45 
Total current liabilities
2,725 
2,461 
Long-term Debt, Net
5,226 
5,504 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
3,340 
3,250 
Accumulated deferred investment tax credits
62 
63 
Regulatory liabilities
1,751 
1,705 
Asset retirement obligations
373 
369 
Pension and other postretirement benefits
480 
466 
Other deferred credits and liabilities
554 
538 
Total deferred credits and other liabilities
6,560 
6,391 
Commitments and Contingencies
   
   
Stockholders' Equity:
 
 
Common Stock
2 
2 
Other paid-in capital
5,602 
5,632 
Retained earnings
906 
907 
Accumulated other comprehensive income (loss)
3 
3 
Stockholder's equity
6,513 
6,544 
Noncontrolling Interest
142 
142 
Total equity
6,655 
6,686 
TOTAL LIABILITIES AND EQUITY
21,166 
21,042 
Union Electric Company
 
 
Current Assets:
 
 
Cash and cash equivalents
   
1 
Accounts receivable - trade (less allowance for doubtful accounts)
218 
191 
Accounts receivable - affiliates
1 
1 
Unbilled revenue
129 
168 
Miscellaneous accounts and notes receivable
67 
57 
Materials and supplies
338 
352 
Current regulatory assets
145 
118 
Other current assets
50 
71 
Total current assets
948 
959 
Property and Plant, Net
10,499 
10,452 
Investments and Other Assets:
 
 
Nuclear decommissioning trust fund
503 
494 
Intangible assets
17 
22 
Regulatory assets
539 
534 
Other assets
442 
443 
Total investments and other assets
1,501 
1,493 
TOTAL ASSETS
12,948 
12,904 
Current Liabilities:
 
 
Current maturities of long-term debt
223 
109 
Short-term Debt
290 
   
Borrowings from money pool
   
105 
Accounts and wages payable
183 
387 
Accounts payable - affiliates
38 
30 
Taxes accrued
252 
220 
Interest accrued
47 
57 
Current regulatory liabilities
47 
57 
Other current liabilities
87 
82 
Total current liabilities
1,167 
1,047 
Long-term Debt, Net
3,535 
3,648 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
2,551 
2,524 
Accumulated deferred investment tax credits
58 
59 
Regulatory liabilities
1,062 
1,041 
Asset retirement obligations
371 
366 
Pension and other postretirement benefits
198 
189 
Other deferred credits and liabilities
43 
37 
Total deferred credits and other liabilities
4,283 
4,216 
Commitments and Contingencies
   
   
Stockholders' Equity:
 
 
Common Stock
511 
511 
Other paid-in capital
1,560 
1,560 
Preferred stock not subject to mandatory redemption
80 
80 
Retained earnings
1,812 
1,842 
Stockholder's equity
3,963 
3,993 
TOTAL LIABILITIES AND EQUITY
12,948 
12,904 
Ameren Illinois Company
 
 
Current Assets:
 
 
Cash and cash equivalents
1 
1 
Accounts receivable - trade (less allowance for doubtful accounts)
328 
201 
Unbilled revenue
107 
135 
Miscellaneous accounts and notes receivable
8 
13 
Materials and supplies
86 
174 
Current regulatory assets
75 
38 
Current accumulated deferred income taxes, net
52 
45 
Other current assets
20 
26 
Total current assets
677 
633 
Property and Plant, Net
5,731 
5,589 
Investments and Other Assets:
 
 
Goodwill
411 
411 
Regulatory assets
706 
701 
Other assets
115 
120 
Total investments and other assets
1,232 
1,232 
TOTAL ASSETS
7,640 
7,454 
Current Liabilities:
 
 
Borrowings from money pool
242 
56 
Accounts and wages payable
230 
243 
Accounts payable - affiliates
28 
18 
Taxes accrued
22 
23 
Customer deposits
80 
79 
Current environmental remediation
46 
43 
Current regulatory liabilities
201 
159 
Other current liabilities
153 
150 
Total current liabilities
1,002 
771 
Long-term Debt, Net
1,692 
1,856 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
1,158 
1,116 
Accumulated deferred investment tax credits
4 
4 
Regulatory liabilities
689 
664 
Pension and other postretirement benefits
200 
197 
Environmental remediation
222 
232 
Other deferred credits and liabilities
173 
166 
Total deferred credits and other liabilities
2,446 
2,379 
Commitments and Contingencies
   
   
Stockholders' Equity:
 
 
Common Stock
0 
0 
Other paid-in capital
1,965 
1,965 
Preferred stock not subject to mandatory redemption
62 
62 
Retained earnings
463 
410 
Accumulated other comprehensive income (loss)
10 
11 
Stockholder's equity
2,500 
2,448 
TOTAL LIABILITIES AND EQUITY
$ 7,640 
$ 7,454 
Consolidated Balance Sheet (Parenthetical) (USD $)
In Millions, except Per Share data, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Accounts receivable - trade allowance for doubtful accounts
$ 26 
$ 18 
Common stock, par value
$ 0.01 
$ 0.01 
Common stock, shares authorized
400.0 
400.0 
Common stock, shares outstanding
242.6 
242.6 
Union Electric Company
 
 
Accounts receivable - trade allowance for doubtful accounts
7 
5 
Common stock, par value
$ 5 
$ 5 
Common stock, shares authorized
150.0 
150.0 
Common stock, shares outstanding
102.1 
102.1 
Ameren Illinois Company
 
 
Accounts receivable - trade allowance for doubtful accounts
$ 18 
$ 13 
Common stock, no par value
   
   
Common stock, shares authorized
45.0 
45.0 
Common stock, shares outstanding
25.5 
25.5 
Consolidated Statement of Cash Flows (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Cash Flows From Operating Activities:
 
 
Net income (loss)
$ 98 
$ (143)
Loss from discontinued operations, net of taxes
1 
199 
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
 
 
Depreciation and amortization
176 
166 
Amortization of nuclear fuel
24 
20 
Amortization of debt issuance costs and premium/discounts
5 
6 
Deferred income taxes and investment tax credits, net
84 
40 
Allowance for equity funds used during construction
(7)1
(8)1
Stock-based compensation costs
9 
9 
Other
(1)
(3)
Changes in assets and liabilities:
 
 
Receivables
(86)
(95)
Materials and supplies
102 
127 
Accounts and wages payable
(183)
(127)
Taxes accrued
18 
41 
Assets, other
(90)
52 
Liabilities, other
49 
29 
Pension and other postretirement benefits
30 
3 
Counterparty collateral, net
10 
26 
Net cash provided by operating activities – continuing operations
239 
342 
Net cash provided by operating activities – discontinued operations
   
37 
Net cash provided by operating activities
239 
379 
Cash Flows From Investing Activities:
 
 
Capital expenditures
(442)
(275)
Nuclear fuel expenditures
(10)
(11)
Purchases of securities - nuclear decommissioning trust fund
(186)
(35)
Sales and maturities of securities - nuclear decommissioning trust fund
182 
32 
Proceeds from Notes Receivable
56 
   
Contributions to Note Receivable
(65)
   
Other
   
(2)
Net cash used in investing activities – continuing operations
(465)
(291)
Net cash provided by (used in) investing activities – discontinued operations
152 
(12)
Net cash used in investing activities
(313)
(303)
Cash Flows From Financing Activities:
 
 
Dividends on common stock
(97)
(97)
Dividends paid to noncontrolling interest holders
(2)
(2)
Short-term debt, net
332 
   
Redemptions of Other Long-term Debt
(163)
   
Net cash provided by (used in) financing activities – continuing operations
70 
(99)
Net cash used in financing activities – discontinued operations
   
   
Net cash provided by (used in) financing activities
70 
(99)
Net change in cash and cash equivalents
(4)
(23)
Cash and cash equivalents at beginning of period
30 
209 
Cash and cash equivalents at end of period
26 
186 
Less cash and cash equivalents at end of period, discontinued operations
   
25 
Cash and cash equivalents at beginning of period
30 
 
Cash and cash equivalents at end of period
26 
161 
Union Electric Company
 
 
Cash Flows From Operating Activities:
 
 
Net income (loss)
48 
41 
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
 
 
Depreciation and amortization
112 
104 
Amortization of nuclear fuel
24 
20 
Amortization of debt issuance costs and premium/discounts
2 
2 
Deferred income taxes and investment tax credits, net
30 
(8)
Allowance for equity funds used during construction
(7)
(7)
Changes in assets and liabilities:
 
 
Receivables
2 
(50)
Materials and supplies
14 
22 
Accounts and wages payable
(153)
(139)
Taxes accrued
30 
38 
Assets, other
(28)
38 
Liabilities, other
7 
5 
Pension and other postretirement benefits
15 
2 
Net cash provided by operating activities
96 
68 
Cash Flows From Investing Activities:
 
 
Capital expenditures
(188)
(137)
Nuclear fuel expenditures
(10)
(11)
Money pool advances, net
   
24 
Purchases of securities - nuclear decommissioning trust fund
(186)
(35)
Sales and maturities of securities - nuclear decommissioning trust fund
182 
32 
Other
(2)
(2)
Net cash used in investing activities
(204)
(129)
Cash Flows From Financing Activities:
 
 
Dividends on common stock
(77)
(90)
Dividends on preferred stock
(1)
(1)
Money pool borrowings, net
(105)
5 
Short-term debt, net
290 
   
Net cash provided by (used in) financing activities
107 
(86)
Net change in cash and cash equivalents
(1)
(147)
Cash and cash equivalents at beginning of period
1 
148 
Cash and cash equivalents at end of period
   
1 
Ameren Illinois Company
 
 
Cash Flows From Operating Activities:
 
 
Net income (loss)
54 
32 
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
 
 
Depreciation and amortization
62 
60 
Amortization of debt issuance costs and premium/discounts
3 
3 
Deferred income taxes and investment tax credits, net
36 
50 
Other
(2)
(1)
Changes in assets and liabilities:
 
 
Receivables
(94)
(58)
Materials and supplies
88 
105 
Accounts and wages payable
14 
9 
Taxes accrued
(1)
3 
Assets, other
(61)
16 
Liabilities, other
71 
24 
Pension and other postretirement benefits
10 
1 
Counterparty collateral, net
12 
27 
Net cash provided by operating activities
192 
271 
Cash Flows From Investing Activities:
 
 
Capital expenditures
(215)
(133)
Money pool advances, net
   
(5)
Other
1 
   
Net cash used in investing activities
(214)
(138)
Cash Flows From Financing Activities:
 
 
Dividends on common stock
   
(15)
Dividends on preferred stock
(1)
(1)
Money pool borrowings, net
186 
(24)
Redemptions of Other Long-term Debt
(163)
   
Net cash provided by (used in) financing activities
22 
(40)
Net change in cash and cash equivalents
   
93 
Cash and cash equivalents at beginning of period
1 
   
Cash and cash equivalents at end of period
$ 1 
$ 93 
Summary Of Significant Accounting Policies
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
General
Ameren, headquartered in St. Louis, Missouri, is a public utility holding company under PUHCA 2005, administered by FERC. Ameren’s primary assets are its equity interests in its subsidiaries. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below. Also see the Glossary of Terms and Abbreviations at the front of this report and in the Form 10-K.
•
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 supplies electric service to 1.2 million customers and natural gas service to 127,000 customers.
•
Ameren Illinois Company, doing business as Ameren Illinois, operates a rate-regulated electric and natural gas transmission and distribution business in Illinois. Ameren Illinois supplies electric service to 1.2 million customers and natural gas service to 807,000 customers.
Ameren has various other subsidiaries responsible for activities such as the provision of shared services. Ameren also has a subsidiary, ATXI, that operates a FERC rate-regulated electric transmission business and is developing the Illinois Rivers project.
The operating results, assets, and liabilities for New AER and the Elgin, Gibson City, Grand Tower, Meredosia, and Hutsonville energy centers have been presented separately as discontinued operations for all periods presented in this report. Unless otherwise stated, these notes to Ameren’s financial statements exclude discontinued operations for all periods presented. On January 31, 2014, Medina Valley completed its sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital. See Note 12 - Divestiture Transactions and Discontinued Operations in this report for additional information regarding the discontinued operations presentation and Note 16 - Divestiture Transactions and Discontinued Operations under Part II, Item 8, of the Form 10-K for additional information regarding Ameren’s divestiture of New AER in December 2013.
The financial statements of Ameren are prepared on a consolidated basis, and therefore include the accounts of its majority-owned subsidiaries. All significant intercompany transactions have been eliminated. Ameren Missouri and Ameren Illinois have no subsidiaries, and therefore their financial statements are not prepared on a consolidated basis. 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. The results of operations of an interim period may not give a true indication of results that may be expected for a full year. These financial statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K.
Earnings Per Share
There were no material differences between Ameren’s basic and diluted earnings per share amounts for the three months ended March 31, 2014, and 2013, caused by the assumed settlement of performance share units. The number of dilutive performance share units had an immaterial impact on earnings per share.
Stock-based Compensation
Ameren’s long-term incentive plan available for eligible employees, the 2006 Omnibus Incentive Compensation Plan (2006 Plan), was replaced prospectively for new grants only by the 2014 Omnibus Incentive Compensation Plan (2014 Plan) effective April 24, 2014. The 2014 Plan provides for a maximum of 8 million common shares to be available for grant to eligible employees and directors, and retains many of the features of the 2006 Plan. The 2014 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 performance share units at March 31, 2014, and changes during the three months ended March 31, 2014, under the 2006 Plan are presented below:
 
Performance Share Units
 
Share Units
Weighted-average Fair Value Per Unit at Grant Date
Nonvested at January 1, 2014
1,218,544

$
33.23

Granted(a)
680,606

38.90

Forfeitures
(46,758
)
33.29

Vested(b)
(116,297
)
38.81

Nonvested at March 31, 2014
1,736,095

$
35.08

(a)
Includes performance share units (share units) granted to certain executive and nonexecutive officers and other eligible employees in 2014 under the 2006 Plan.
(b)
Share units vested due to the 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.
The fair value of each share unit awarded in 2014 under the 2006 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 stockholder 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.
Intangible Assets
Ameren and Ameren Missouri classify renewable energy credits and emission allowances as intangible assets. Ameren Illinois consumes renewable energy credits as they are purchased through the IPA procurement process and expenses them immediately. We evaluate intangible assets for impairment if events or changes in circumstances indicate that their carrying amount might be impaired.
At March 31, 2014, Ameren’s and Ameren Missouri’s intangible assets consisted of renewable energy credits obtained through wind and solar power purchase agreements. The book value of Ameren’s and Ameren Missouri’s renewable energy credits was $17 million each at March 31, 2014. The book value of Ameren’s and Ameren Missouri’s renewable energy credits was $22 million each at December 31, 2013.
Ameren Missouri’s and Ameren Illinois’ renewable energy credits and Ameren Missouri’s emission allowances are charged to “Purchased power” expense and “Fuel” expense, respectively, as they are used in operations. The following table presents amortization expense based on usage of renewable energy credits and emission allowances, net of gains from sales, for Ameren, Ameren Missouri and Ameren Illinois, during the three months ended March 31, 2014, and 2013:
 
Three Months
 
2014
 
2013
Ameren Missouri
$
6

(a) 
$
(b)

Ameren Illinois
 
3

 
 
4

Ameren
$
9

 
$
4

(a)
Includes higher priced renewable energy credits. 
(b)
Less than $1 million.
Excise Taxes
Excise taxes levied on us are reflected on Ameren Missouri electric customer bills and on Ameren Missouri and Ameren Illinois natural gas customer bills. They are recorded gross in “Operating Revenues - Electric,” “Operating Revenues - Gas” and “Operating Expenses - Taxes other than income taxes” on the statement of income or the statement of income and comprehensive income. Excise taxes reflected on Ameren Illinois electric customer bills are imposed on the customer and are therefore not included in revenues and expenses. They are included in “Taxes accrued” on the balance sheet. The following table presents excise taxes recorded in “Operating Revenues - Electric,” “Operating Revenues - Gas” and “Operating Expenses - Taxes other than income taxes” for the three months ended March 31, 2014, and 2013:
 
Three months
 
2014
 
2013
Ameren Missouri
$
34

 
$
33

Ameren Illinois
26

 
22

Ameren
$
60

 
$
55


Uncertain Tax Positions
The following table presents the amount of unrecognized tax benefits (detriments) as of March 31, 2014, and December 31, 2013:
 
March 31,
2014
 
December 31,
2013
 
 
Ameren
$
92

 
$
90

Ameren Missouri
32

 
31

Ameren Illinois
(1
)
 
(1
)

With the adoption of new accounting guidance in the first quarter of 2014, unrecognized tax benefits are recorded in “Accumulated deferred income taxes, net” as a reduction to the deferred tax assets for net operating loss and tax credit carryforwards on Ameren’s, Ameren Missouri’s and Ameren Illinois’ balance sheets. Unrecognized tax benefits that exceed these carryforwards are recorded in “Other deferred credits and liabilities” on the respective balance sheets. At March 31, 2014, unrecognized tax benefits of $84 million, $14 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 the respective balance sheets were reclassified to “Accumulated deferred income taxes, net” for comparative purposes. For additional information see the Accounting and Reporting Developments section below.
The following table presents the amount of unrecognized tax benefits (detriments) as of March 31, 2014, and 2013, that would impact the effective tax rate, if recognized:
 
March 31,
2014
 
December 31,
2013
 
 
Ameren
$
55

 
$
54

Ameren Missouri
2

 
3

Ameren Illinois
(1
)
 
—


Ameren’s federal income tax returns for the years 2007 through 2011 are before the Appeals Office of the IRS. Ameren’s federal income tax return for the year 2012 is currently under examination.
It is reasonably possible that a settlement will be reached with the Appeals Office of the IRS in the next 12 months for the years 2007 through 2011. This settlement, which is primarily related to uncertain tax positions for research tax deductions, is expected to result in a decrease in uncertain tax benefits of $20 million and $13 million for Ameren and Ameren Missouri, respectively. In addition, it is reasonably possible that other events will occur during the next 12 months that would cause the total amount of unrecognized tax benefits for the Ameren Companies to increase or decrease. However, the Ameren Companies do not believe any such increases or decreases, including the decrease from the reasonably possible IRS Appeals Office settlement discussed above, would be material to their results of operations, financial position, or liquidity.
State income tax returns are generally subject to examination for a period of three years after filing of the return. The Ameren Companies do not currently have material state income tax issues under examination, administrative appeals, or litigation. 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.
Asset Retirement Obligations
AROs at Ameren, Ameren Missouri and Ameren Illinois increased at March 31, 2014, compared to December 31, 2013, to reflect the accretion of obligations to their fair value, partially offset by immaterial settlements.
Noncontrolling Interests
As of March 31, 2014, Ameren's noncontrolling interests were composed of the preferred stock not subject to mandatory redemption of Ameren Missouri and Ameren Illinois. All noncontrolling interests are classified as a component of equity separate from Ameren's equity on its consolidated balance sheet. A reconciliation of the equity changes attributable to the noncontrolling interests at Ameren for the three months ended March 31, 2014, and 2013, are shown below:
  
Three Months
 
  
2014
 
2013
 
Noncontrolling interests, beginning of period
$
142

 
$
151

(a) 
Net income from continuing operations attributable to noncontrolling interests
2

 
2

 
Dividends paid to noncontrolling interest holders
(2
)
 
(2
)
 
Noncontrolling interests, end of period
$
142

 
$
151

(a) 
(a)
Included the 20% EEI ownership interest not owned by Ameren prior to the divestiture of New AER to IPH. Prior to the divestiture of New AER, the assets and liabilities of EEI were consolidated in Ameren’s balance sheet at a 100% ownership level and were included in “Assets of discontinued operations” and “Liabilities of discontinued operations.” The divestiture of New AER, which included EEI, was completed in the fourth quarter of 2013. See Note 12 - Divestiture Transactions and Discontinued Operations for additional information.
Accounting and Reporting Developments
The following is a summary of recently adopted authoritative accounting guidance.
Presentation of an Unrecognized Tax Benefit
In July 2013, FASB issued additional authoritative accounting guidance to provide clarity for the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. 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 to the extent a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is available under the tax law. This guidance was effective for the Ameren Companies beginning in the first quarter of 2014. Previously, unrecognized tax benefits were recorded in “Other deferred credits and liabilities” on Ameren's, Ameren Missouri's and Ameren Illinois' balance sheets. Beginning in the first quarter 2014, unrecognized tax benefits are recorded in “Accumulated deferred income taxes, net” as a reduction to the deferred tax assets for net operating loss and tax credit carryforwards on the respective balance sheets. Unrecognized tax benefits that exceed these carryforwards are recorded in “Other deferred credits and liabilities,” on the respective balance sheets. For comparative purposes, the Ameren Companies reclassified the December 31, 2013 balances in accordance with the new guidance as discussed in the Uncertain Tax Positions section above. 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.
Rate And Regulatory Matters
RATE AND REGULATORY MATTERS
RATE AND REGULATORY MATTERS
Below is a summary of updates to significant regulatory proceedings and related lawsuits. See also Note 2 - Rate and Regulatory Matters under Part II, Item 8, of the Form 10-K. We are unable to predict the ultimate outcome of these matters, the timing of the final decisions of the various agencies and courts, or the impact on our results of operations, financial position, or liquidity.
Missouri
Accounting Authority Order
In July 2011, Ameren Missouri filed a request with the MoPSC for an accounting authority order that would allow Ameren Missouri to defer fixed costs totaling $36 million that were not previously recovered from Noranda as a result of the loss of load caused by the severe 2009 ice storm for potential recovery in a future electric rate case. In November 2013, the MoPSC issued an order approving Ameren Missouri’s request for an accounting authority order, which will allow Ameren Missouri to seek recovery of these fixed costs in a future electric rate case. Ameren Missouri will seek to recover these fixed costs in its next electric rate case, which it will file by July 15, 2014. In February 2014, MIEC and MoOPC filed appeals of the accounting authority order to the Missouri Court of Appeals, Western District.
Earnings Complaint and Rate Shift Complaint Cases
In February 2014, Ameren Missouri’s largest customer, Noranda, and 37 residential customers filed an earnings complaint case and a rate shift complaint case with the MoPSC. In the earnings complaint case, Noranda and the residential customers asserted that Ameren Missouri’s electric service business is earning more than the 9.8% return on equity authorized in the MoPSC's December 2012 electric rate order and requested that the MoPSC approve a $67 million reduction to Ameren Missouri’s annual revenue requirement. Included in Noranda’s request is a reduction of Ameren Missouri’s authorized return on equity to 9.4%. The rate shift complaint case seeks to reduce Noranda’s electricity cost with an offsetting increase in electricity cost for Ameren Missouri’s other customers. While the rate shift proposal is revenue neutral to Ameren Missouri, Ameren Missouri does not believe that the proposed reduction to Noranda’s electric rates, which are significantly below Ameren Missouri’s cost of service, is appropriate or in the best interests of Ameren Missouri’s other electric customers. The MoOPC and MIEC have intervened in the earnings complaint case.
While the MoPSC has no time requirement by which it must issue an order in these cases, it has adopted procedural schedules that would render a decision in the rate shift case by August 6, 2014, and in the earnings complaint case by September 26, 2014. Ameren Missouri does not believe that a reduction in electric service rates is justified and will file testimony that supports that position, which is consistent with Ameren Missouri’s expected July 2014 rate case filing. The MoPSC has 11 months from when Ameren Missouri files its request to issue an order.
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 in effect for that year and its estimate of the probable increase or decrease in the revenue requirement expected to ultimately be approved by the ICC based on that year's actual costs incurred. As of March 31, 2014, Ameren Illinois had recorded a regulatory asset of $24 million to reflect its expected 2014 revenue requirement reconciliation adjustment, with interest.
In September 2012 and December 2012, the ICC issued orders in Ameren Illinois’ IEIMA performance-based formula rate filings. Ameren Illinois appealed both orders to the Appellate Court of the Fourth District of Illinois. The primary issues Ameren Illinois appealed were the rate treatment of accumulated deferred income taxes and vacation obligations as well as the calculation of Ameren Illinois’ capital structure. In December 2013, the appellate court rendered its decision upholding the ICC’s September and December 2012 orders. Ameren Illinois filed an appeal to the Illinois Supreme Court in March 2014.
In December 2013, the ICC issued an order in Ameren Illinois' annual update filing, which was based on 2012 recoverable costs and expected net plant additions for 2013. The ICC order established rates for 2014. In February 2014, Ameren Illinois filed an appeal to the Appellate Court of the Fourth District of Illinois regarding the calculation of its capital structure and the rate treatment of accumulated deferred income taxes related to the transfer of former Ameren Missouri assets in Illinois to Ameren Illinois.
In April 2014, Ameren Illinois filed with the ICC its annual electric delivery service formula rate update to establish the revenue requirement used to set rates for 2015. Pending ICC approval, Ameren Illinois’ update filing will result in a $206 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 annual reconciliation of the revenue requirement in effect for 2013 to the actual costs incurred in that year; and an increase resulting from the conclusion of a refund to customers in 2014 for the 2012 revenue requirement reconciliation. An ICC decision on this April 2014 filing is expected by December 2014.
2013 Natural Gas Delivery Service Rate Case
In December 2013, the ICC issued a rate order that approved an increase in revenues for natural gas delivery service of $32 million. The revenue increase was based on a 9.1% return on equity, a capital structure composed of 51.7% common equity, and a rate base of $1.1 billion. The rate order was based on a 2014 future test year. The rate changes became effective January 1, 2014. In March 2014, Ameren Illinois filed an appeal of the allowed return on equity included in the ICC's order with the Appellate Court of the Fourth District of Illinois. Ameren Illinois sought a 10.4% return on equity in this rate case.
Federal
2011 Wholesale Distribution Rate Case
In January 2011, Ameren Illinois filed a request with FERC to increase its annual revenues for electric delivery service for its wholesale customers. These wholesale distribution revenues are treated as a deduction from Ameren Illinois’ revenue requirement in retail rate filings with the ICC. In March 2011, FERC issued an order authorizing the proposed rates to take effect, subject to refund when the final rates are determined. Ameren Illinois has reached a settlement with four of its nine wholesale customers, which have been approved by FERC and refunds have been issued. The impasse with the remaining five wholesale customers is awaiting final FERC action. In November 2012, a FERC administrative law judge issued an initial decision, which is now pending before FERC. The timing of a decision from FERC is uncertain and subsequent appeals are possible. In accordance with the administrative law judge's initial decision, Ameren and Ameren Illinois have both included on their balance sheets in “Current regulatory liabilities” an estimate of $14 million and $13 million as of March 31, 2014, and December 31, 2013, respectively, for the refund due to the remaining wholesale customers relating to billings for the period from March 2011 through March 2014.
Ameren Illinois Electric Transmission Rate Refund
In July 2012, FERC issued an order concluding that Ameren Illinois improperly included acquisition premiums, primarily goodwill, in determining the common equity used in its electric transmission formula rate, and thereby inappropriately recovered a higher amount from its electric transmission customers. The order required Ameren Illinois to make refunds to customers for such improperly included amounts. In August 2012, Ameren Illinois filed a request for a rehearing of this order. It is unknown when FERC will rule on Ameren's rehearing request, as it is under no deadline to do so.
Ameren Illinois submitted a refund report in November 2012 and concluded that no refund was warranted. Several wholesale customers filed a protest with FERC regarding Ameren's conclusion that no refund was warranted. In June 2013, FERC issued an order that rejected Ameren Illinois' November 2012 refund report and provided guidance as to the filing of a new refund report. In July 2013, Ameren Illinois filed a revised refund report based on the guidance provided in the June 2013 order, as well as a request for a rehearing of that order. Ameren Illinois' July 2013 refund report also concluded that no refund was warranted. Ameren Illinois estimated the maximum pretax charge to earnings for this possible refund obligation through December 31, 2014 would be $19 million, before interest charges. If Ameren Illinois were to determine that a refund to its electric transmission customers is probable, a charge to earnings would be recorded for the refund in the period in which that determination was made.
FERC Complaint Case
In November 2013, a customer group filed a complaint case with FERC seeking a reduction in the allowed return on common equity to 9.15%, as well as a limit on the common equity ratio, under the MISO tariff. Currently, the FERC-allowed return on common equity for MISO transmission owners is 12.38%. This complaint case could result in a reduction to Ameren Illinois' and ATXI's allowed return on common equity. That reduction could also result in a refund for transmission service revenues earned after the filing of the complaint case in November 2013. FERC has not issued an order in this case, and it is under no deadline to do so. Ameren is not able to predict if or how FERC will rule on this complaint case.
Ameren Missouri Power Purchase Agreement with Entergy
Beginning in 2005, FERC issued a series of orders addressing a complaint filed in 2001 by the Louisiana Public Service Commission against Entergy and certain of its affiliates. The complaint alleged unjust and unreasonable cost allocations. As a result of the FERC orders, Entergy began billing Ameren Missouri in 2007 for additional charges under a 165-megawatt power purchase agreement, which expired August 31, 2009. In May 2012, FERC issued an order stating that Entergy should not have included additional charges to Ameren Missouri under the power purchase agreement. Pursuant to the order, in June 2012, Entergy paid Ameren Missouri $31 million. In July 2012, Entergy filed an appeal of FERC's January 2010 and May 2012 orders to the United States Court of Appeals for the District of Columbia Circuit, which was subsequently dismissed on a procedural issue. In November 2013, Entergy refiled the appeal of FERC's May 2012 order with the United States Court of Appeals for the District of Columbia Circuit. Ameren is not able to predict when or how the court will rule on Entergy's appeal.
The Louisiana Public Service Commission appealed 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. In April 2008, that court ordered further FERC proceedings regarding Louisiana Public Service Commission’s complaint. The court ordered FERC to explain its previous denial of retroactive refunds and the implementation of prospective charges. FERC’s decision on remand of the retroactive impact of these issues could have a financial impact on Ameren Missouri. Ameren Missouri is unable to predict when or how FERC will respond to the court’s decisions. Ameren Missouri estimates that it could incur an additional expense of up to $25 million if FERC orders retroactive application for the years 2001 to 2005. Ameren Missouri believes that the likelihood of incurring any expense is not probable, and therefore no liability has been recorded as of March 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 its existing Missouri nuclear energy center site, and the NRC suspended review of the COL application.
Ameren Missouri estimated the total cost required to obtain a small modular reactor COL to be $80 million to $100 million. As of March 31, 2014, Ameren Missouri had capitalized investments of $69 million for the development of a new nuclear energy center. Ameren Missouri is currently evaluating all potential nuclear technologies in order to maintain an option for nuclear power in the future.
All of Ameren Missouri's capitalized investments for the development of a new nuclear energy center will remain capitalized while management pursues options to maximize the value of its investment. If efforts to license additional nuclear generation are abandoned or management concludes it is probable the costs incurred will be disallowed in rates, a charge to earnings would be recognized in the period in which that determination is made.
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 credit agreements, or commercial paper issuances.
The 2012 Missouri Credit Agreement and the 2012 Illinois Credit Agreement, both of which expire on November 14, 2017, were not utilized for direct borrowings during the three months ended March 31, 2014, but they were used to support commercial paper issuances and to issue letters of credit. As of March 31, 2014, based on letters of credit issued under the 2012 Credit Agreements, as well as commercial paper outstanding, the aggregate amount of credit capacity available to Ameren (parent), Ameren Missouri and Ameren Illinois, collectively, at March 31, 2014, was $1.4 billion.
Commercial Paper
Ameren (parent) had $410 million and $368 million of commercial paper outstanding at March 31, 2014, and December 31, 2013, respectively. Ameren Missouri had $290 million and $- million of commercial paper outstanding at March 31, 2014, and December 31, 2013, respectively.
The following table summarizes the commercial paper activity and relevant interest rates under Ameren’s (parent) and Ameren Missouri’s commercial paper programs for the three months ended March 31, 2014, and 2013:
 
 
Ameren (parent)
Ameren Missouri
Ameren Consolidated
2014
 
 
 
 
 
Average daily commercial paper outstanding
 
$
339

 
$
200

$
539

Weighted-average interest rate
 
0.45
%
 
0.45
%
0.45
%
Peak commercial paper during period(a)
 
$
452

 
$
290

$
700

Peak interest rate
 
0.75
%
 
0.70
%
0.75
%
2013
 
 
 
 
 
Average daily commercial paper outstanding
 
$
2

 
$
—

$
2

Weighted-average interest rate
 
0.80
%
 
—
%
0.80
%
Peak commercial paper during period(a)
 
$
21

 
$
—

$
21

Peak interest rate
 
0.85
%
 
—
%
0.85
%

(a)
The timing of peak commercial paper issuances varies by company, and therefore the amounts presented by company might not equal the Ameren Consolidated peak commercial paper issuances for the period.
Indebtedness Provisions and Other Covenants
The information below presents a summary of the Ameren Companies’ compliance with indebtedness provisions and other covenants within the 2012 Credit Agreements. See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, in the Form 10-K for a detailed description of these provisions.
The 2012 Credit Agreements 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 March 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 44%, for Ameren, Ameren Missouri and Ameren Illinois, respectively. In addition, under the 2012 Illinois Credit Agreement and by virtue of the cross-default provisions of the 2012 Missouri Credit Agreement, Ameren is required to maintain a ratio of consolidated funds from operations plus interest expense to consolidated interest expense of at least 2.0 to 1.0, to be calculated quarterly, as of the end of the most recent four fiscal quarters then ending, in accordance with the 2012 Illinois Credit Agreement. Ameren’s ratio as of March 31, 2014, was 5.6 to 1.0. Failure of a borrower to satisfy a financial covenant constitutes an immediate default under the applicable 2012 Credit Agreement. The calculation of Ameren’s ratios discussed above includes both continuing and discontinued operations.
None of the Ameren Companies' credit agreements or financing arrangements contain credit rating triggers that would cause a default or acceleration of repayment of outstanding balances. The Ameren Companies were in compliance with the provisions and covenants of their credit agreements at March 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 Services is responsible for the operation and administration of the money pool agreements.
Ameren Missouri, Ameren Illinois and Ameren Services may participate in the utility money pool as both lenders and borrowers. Ameren may participate in the money pools only as a lender. Surplus internal funds are contributed to the money pool from participants. The primary sources of external funds for the money pool are the 2012 Credit Agreements and the commercial paper programs. The total amount available to the pool participants from the money pool at any given time is reduced by the amount of borrowings made by participants, but is increased to the extent that the pool participants advance surplus funds to the money pool or remit funds from other external sources. The availability of funds is also determined by funding requirement limits established by regulatory authorizations. Participants receiving a loan under the money pool agreement must repay the principal amount of such loan, together with accrued interest. The rate of interest depends on the composition of internal and external funds in the money pool. The average interest rate for borrowing under the utility money pool for the three months ended March 31, 2014, was 0.39% (2013 - 0.11%).
See Note 8 - Related Party Transactions for the amount of interest income and expense from the money pool arrangements recorded by the Ameren Companies for the three months ended March 31, 2014, and 2013.
Long-Term Debt And Equity Financings
LONG-TERM DEBT AND EQUITY FINANCINGS
LONG-TERM DEBT AND EQUITY FINANCINGS
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 $348 million. The proceeds were used to repay a portion of its short-term debt and will be used to repay at maturity $104 million of its 5.50% senior secured notes due May 15, 2014.
Ameren Illinois
In January 2014, Ameren Illinois redeemed the following environmental improvement and pollution control revenue bonds at par value plus accrued interest:
Environmental improvement and pollution control revenue bonds
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.
Indenture Provisions and Other Covenants
Ameren Missouri’s and Ameren Illinois’ indentures and articles of incorporation include covenants and provisions related to issuances of first mortgage bonds and preferred stock. Ameren Missouri and Ameren Illinois are required to meet certain ratios to issue additional first mortgage bonds and preferred stock. A failure to achieve these ratios would not result in a default under these covenants and provisions, but would restrict the companies’ ability to issue bonds or preferred stock. The following table summarizes the required and actual interest coverage ratios for interest charges and dividend coverage ratios and bonds and preferred stock issuable as of March 31, 2014, at an assumed annual interest rate of 6% and dividend rate of 7%.
 
 
Required Interest
Coverage Ratio(a)
 
Actual Interest
Coverage Ratio
 
Bonds Issuable(b)
 
Required Dividend
Coverage Ratio(c)
 
Actual Dividend
Coverage Ratio
 
Preferred Stock
Issuable
 
Ameren Missouri
 
≥2.0
 
4.7
$
4,018

 
≥2.5
 
118.8
$
2,272

 
Ameren Illinois
 
≥2.0
 
7.6
 
3,732

(d) 
≥1.5
 
2.7
 
203

(e) 
(a)
Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.
(b)
Amount of bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include bonds issuable based on retired bond capacity of $729 million and $454 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.
(e)
Preferred stock issuable is restricted by the amount of preferred stock that is currently authorized by Ameren Illinois’ articles of incorporation.
Ameren’s indenture does not require Ameren to comply with any quantitative financial covenants. The indenture does, however, include certain cross-default provisions. Specifically, either (1) the failure by Ameren to pay when due and upon expiration of any applicable grace period any portion of any Ameren indebtedness in excess of $25 million or (2) the acceleration upon default of the maturity of any Ameren indebtedness in excess of $25 million under any indebtedness agreement, including the 2012 Credit Agreements, constitutes a default under the indenture, unless such past due or accelerated debt is discharged or the acceleration is rescinded or annulled within a specified period.
Ameren Missouri and Ameren Illinois and certain other Ameren subsidiaries are subject to Section 305(a) of the Federal Power Act, which makes it unlawful for any officer or director of a public utility, as defined in the Federal Power Act, to participate in the making or paying of any dividend from any funds “properly included in capital account.” FERC has consistently interpreted the provision to allow dividends to be paid as long as (1) the source of the dividends is clearly disclosed, (2) the dividends are not excessive, and (3) there is no self-dealing on the part of corporate officials. At a minimum, Ameren believes that dividends can be paid by its subsidiaries that are public utilities from net income and retained earnings. In addition, under Illinois law, Ameren Illinois may not pay any dividend on its stock, unless, among other things, its earnings and earned surplus are sufficient to declare and pay a dividend after provision is made for reasonable and proper reserves, or unless Ameren Illinois has specific authorization from the ICC.
Ameren Illinois’ articles of incorporation require dividend payments on its common stock to be based on ratios of common stock to total capitalization and other provisions related to certain operating expenses and accumulations of earned surplus. Ameren Illinois committed to FERC to maintain a minimum 30% ratio of common stock equity to total capitalization. As of March 31, 2014, Ameren Illinois’ ratio of common stock equity to total capitalization was 55%.
In order for the Ameren Companies to issue securities in the future, they will have to comply with all applicable requirements in effect at the time of any such issuances.
Off-Balance-Sheet Arrangements
At March 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 - 12 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 three months ended March 31, 2014, and 2013:
 
Three Months
 
 
2014
 
2013
 
Ameren:(a)
 
 
 
 
Miscellaneous income:
 
 
 
 
Allowance for equity funds used during construction
$
7

 
$
8

 
Interest income on industrial development revenue bonds
7

 
7

 
Interest and dividend income
2

 
—

 
Other
2

 
—

 
Total miscellaneous income
$
18

 
$
15

 
Miscellaneous expense:
 
 
 
 
Donations
$
5

 
$
4

 
Other
4

 
4

 
Total miscellaneous expense
$
9

 
$
8

 
Ameren Missouri:
 
 
 
 
Miscellaneous income:
 
 
 
 
Allowance for equity funds used during construction
$
7

 
$
7

 
Interest income on industrial development revenue bonds
7

 
7

 
Total miscellaneous income
$
14

 
$
14

 
Miscellaneous expense:
 
 
 
 
Donations
$
2

 
$
2

 
Other
2

 
3

 
Total miscellaneous expense
$
4

 
$
5

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

 
$
1

 
Interest and dividend income
2

 
—

 
Other
1

 
—

 
Total miscellaneous income
$
3

 
$
1

 
Miscellaneous expense:
 
 
 
 
Donations
$
3

 
$
3

 
Other
1

 
—

 
Total miscellaneous expense
$
4

 
$
3

 
(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
Derivative Financial Instruments
DERIVATIVE FINANCIAL INSTRUMENTS
DERIVATIVE FINANCIAL INSTRUMENTS
We use derivatives principally to manage the risk of changes in market prices for natural gas, diesel, power, and uranium. Such price fluctuations may cause the following:
•
an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices;
•
market values of natural gas and uranium inventories that differ from the cost of those commodities in inventory; and
•
actual cash outlays for the purchase of these commodities that differ from anticipated cash outlays.
The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty.
The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of March 31, 2014, and December 31, 2013. As of March 31, 2014, these contracts ran through October 2016, October 2019, May 2032, and October 2016 for fuel oils, natural gas, power, and uranium, respectively.
  
Quantity (in millions, except as indicated)
 
2014
2013
Commodity
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Fuel oils (in gallons)(a)
53

(b)

53

66

(b)

66

Natural gas (in mmbtu)
28

109

137

28

108

136

Power (in megawatthours)
2

11

13

3

11

14

Uranium (pounds in thousands)
827

(b)

827

796

(b)

796

(a)
Fuel oils consist of ultra-low-sulfur diesel, on-highway 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 7 - Fair Value Measurements for a discussion of our methods of assessing the fair value of derivative instruments. Many of our physical contracts, such as our purchased power contracts, qualify for the NPNS exception to derivative accounting rules. The revenue or expense on NPNS contracts is recognized at the contract price upon physical delivery.
If we determine that a contract meets the definition of a derivative and is not eligible for the NPNS exception, we review the contract to determine if it qualifies for hedge accounting. We also consider whether gains or losses resulting from such derivatives qualify for regulatory deferral. Derivative contracts that qualify for regulatory deferral are recorded at fair value, with changes in fair value recorded as regulatory assets or regulatory liabilities in the period in which the change occurs. Ameren Missouri and Ameren Illinois believe derivative 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 March 31, 2014, and December 31, 2013, all contracts that qualify for hedge accounting received regulatory deferral.
Authoritative accounting guidance permits companies to offset fair value amounts recognized for the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a liability) against fair value amounts recognized for derivative instruments that are executed with the same counterparty under the same master netting arrangement. The Ameren Companies did not elect to adopt this guidance for any eligible commodity contracts.
The following table presents the carrying value and balance sheet location of all derivative instruments as of March 31, 2014, and December 31, 2013:
 
Balance Sheet Location
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2014
 
 
 
 
 
 
Derivative assets not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current assets
 
$
5

 
$
—

 
$
5

 
Other assets
 
1

 
—

 
1

Natural gas
Other current assets
 
1

 
5

 
6

 
Other assets
 
1

 
—

 
1

Power
Other current assets
 
15

 
—

 
15

 
Total assets
 
$
23

 
$
5

 
$
28

Derivative liabilities not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current liabilities
 
$
2

 
$
—

 
$
2

 
Other deferred credits and liabilities
 
2

 
—

 
2

Natural gas
Other current liabilities
 
4

 
16

 
20

 
Other deferred credits and liabilities
 
4

 
13

 
17

Power
Other current liabilities
 
6

 
8

 
14

 
Other deferred credits and liabilities
 
—

 
112

 
112

Uranium
Other current liabilities
 
4

 
—

 
4

 
Other deferred credits and liabilities
 
1

 
—

 
1

 
Total liabilities
 
$
23

 
$
149

 
$
172

2013
 
 
 
 
 
 
Derivative assets not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current assets
 
$
6

 
$
—

 
$
6

 
Other assets
 
3

 
—

 
3

Natural gas
Other current assets
 
1

 
1

 
2

Power
Other current assets
 
23

 
—

 
23

 
Total assets
 
$
33

 
$
1

 
$
34

Derivative liabilities not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current liabilities
 
$
2

 
$
—

 
$
2

 
Other deferred credits and liabilities
 
1

 
—

 
1

Natural gas
Other current liabilities
 
5

 
27

 
32

 
Other deferred credits and liabilities
 
6

 
19

 
25

Power
Other current liabilities
 
4

 
9

 
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)
Includes derivatives subject to regulatory deferral.

The following table presents the cumulative amount of pretax net gains (losses) on all derivative instruments deferred as regulatory assets or regulatory liabilities as of March 31, 2014, and December 31, 2013:
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2014
 
 
 
 
 
Cumulative gains (losses) deferred as regulatory liabilities or assets:
 
 
 
 
 
Fuel oils derivative contracts(a)
$
—

 
$
—

 
$
—

Natural gas derivative contracts(b)
(6
)
 
(24
)
 
(30
)
Power derivative contracts(c)
9

 
(120
)
 
(111
)
Uranium derivative contracts(d)
(5
)
 
—

 
(5
)
2013
 
 
 
 
 
Cumulative gains (losses) deferred as regulatory liabilities or assets:
 
 
 
 
 
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 gains (losses) on fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s transportation costs for coal through December 2016 as of March 31, 2014. Current gains deferred as regulatory liabilities include $2 million and $2 million at Ameren and Ameren Missouri, respectively, as of March 31, 2014. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri, respectively, as of March 31, 2014.
(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 2017 at Ameren Illinois, in each case as of March 31, 2014. Current gains deferred as regulatory liabilities include $6 million, $1 million, and $5 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of March 31, 2014. Current losses deferred as regulatory assets include $20 million, $4 million, and $16 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of March 31, 2014.
(c)
Represents net gains (losses) associated with power derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri, in each case as of March 31, 2014. Current gains deferred as regulatory liabilities include $15 million and $15 million at Ameren and Ameren Missouri, respectively, as of March 31, 2014. Current losses deferred as regulatory assets include $14 million, $6 million, and $8 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of March 31, 2014.
(d)
Represents net losses on uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s uranium requirements through December 2016, as of March 31, 2014. Current losses deferred as regulatory assets include $4 million and $4 million at Ameren and Ameren Missouri, respectively, as of March 31, 2014.
Derivative instruments are subject to various credit-related losses in the event of nonperformance by counterparties to the transaction. Exchange-traded contracts are supported by the financial and credit quality of the clearing members of the respective exchanges and have nominal credit risk. In all other transactions, we are exposed to credit risk. Our credit risk management program involves establishing credit limits and collateral requirements for counterparties, using master trading and netting agreements, and reporting daily exposure to senior management.
We believe that entering into master trading and netting agreements mitigates the level of financial loss that could result from default by allowing net settlement of derivative assets and liabilities. We generally enter into the following master trading and netting agreements: (1) the International Swaps and Derivatives Association Agreement, a standardized financial natural gas and electric contract; (2) the Master Power Purchase and Sale Agreement, created by the Edison Electric Institute and the National Energy Marketers Association, a standardized contract for the purchase and sale of wholesale power; and (3) the North American Energy Standards Board Inc. agreement, a standardized contract for the purchase and sale of natural gas. These master trading and netting agreements allow the counterparties to net settle sale and purchase transactions. Further, collateral requirements are calculated at the master trading and netting agreement level by counterparty.
Although Ameren had not previously elected to offset fair value amounts and collateral for derivative instruments executed with the same counterparty under the same master netting arrangement, authoritative accounting guidance requires those amounts eligible to be offset to be presented both at the gross and net amounts. The following table provides the recognized gross derivative balances and the net amounts of those derivatives subject to an enforceable master netting arrangement or similar agreement as of March 31, 2014, and December 31, 2013:
 
 
 
 
Gross Amounts Not Offset in the Balance Sheet
 
 
Commodity Contracts Eligible to be Offset
 
Gross Amounts Recognized in the Balance Sheet
 
Derivative Instruments
 
Cash Collateral Received/Posted(a)
 
Net
Amount
2014
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
23

 
$
9

 
$
—

 
$
14

Ameren Illinois
 
5

 
3

 
—

 
2

Ameren
 
$
28

 
$
12

 
$
—

 
$
16

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
23

 
$
9

 
$
9

 
$
5

Ameren Illinois
 
149

 
3

 
3

 
143

Ameren
 
$
172

 
$
12

 
$
12

 
$
148

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 accrual and NPNS contracts. As of March 31, 2014, if counterparty groups were to fail completely to perform on contracts, Ameren, Ameren Missouri and Ameren Illinois' maximum exposure was $14 million, $9 million, and $5 million, respectively. As of December 31, 2013, if counterparty groups were to fail completely to perform on contracts, Ameren, Ameren Missouri and Ameren Illinois' maximum exposure was $13 million, $12 million, and $1 million, respectively. The potential loss on counterparty exposures is reduced by the application of master trading and netting agreements and collateral held to the extent of reducing the exposure to zero. As of March 31, 2014, the potential loss after consideration of the application of master trading and netting agreements and collateral held for Ameren, Ameren Missouri and Ameren Illinois was $5 million, $3 million, and $2 million, respectively. As of December 31, 2013, the potential loss after consideration of the application of master trading and netting agreements and collateral held for Ameren and Ameren Missouri was $6 million and $6 million, respectively.
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 March 31, 2014, and December 31, 2013, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a gross liability position, the cash collateral posted, and the aggregate amount of additional collateral that could be required to be posted with counterparties. The additional collateral required is the net liability position allowed under the master trading and netting agreements, assuming (1) the credit risk-related contingent features underlying these agreements were triggered on March 31, 2014, or December 31, 2013, respectively, and (2) those counterparties with rights to do so requested collateral.
 
Aggregate Fair Value of
Derivative Liabilities(a)
 
Cash
Collateral Posted
 
Potential Aggregate Amount of
Additional  Collateral Required(b)
2014
 
 
 
 
 
Ameren Missouri
$
56

 
$
2

 
$
51

Ameren Illinois
80

 
3

 
65

Ameren
$
136

 
$
5

 
$
116

2013
 
 
 
 
 
Ameren Missouri
$
70

 
$
2

 
$
67

Ameren Illinois
75

 
15

 
55

Ameren
$
145

 
$
17

 
$
122

(a)
Prior to consideration of master trading and netting agreements and including NPNS and accrual contract exposures.
(b)
As collateral requirements with certain counterparties are based on master trading and netting agreements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such agreements.
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 of 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 derivative 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 as of March 31, 2014:
 
 
Fair Value
 
 
 
Weighted Average
 
 
Assets
Liabilities
Valuation Technique(s)
Unobservable Input
Range
Level 3 Derivative asset and liability - commodity contracts(a):
 
 
 
Ameren
Fuel oils
$
5

$
(4
)
Option model
Volatilities(%)(b)
13 - 34
16
 
 
 
 
Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.25 - 0.99
0.63
 
Natural gas
1

(1
)
Option model
Volatilities(%)(b)
27 - 102
40
 
 
 
 
 
Nodal basis($/mmbtu)(c)
(0.3) - (0.2)
(0.2)
 
 
 
 
Discounted cash flow
Nodal basis($/mmbtu)(c)
(0.2) - (0.1)
(0.1)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.27 - 5
1
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
0.43
(e)
 
Power(f)
14

(124
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)
27 - 57
33
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(1,109) - 2,981
474
 
 
 
 
 
Nodal basis($/MWh)(c)
(6) - (1)
(3)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.35
(e)
 
 
 
 
 
Ameren Missouri and Ameren Illinois credit risk(%)(c)(d)
0.43
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 6
5
 
 
 
 
 
Escalation rate(%)(b)(g)
2 - 3
3
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
 
Uranium
—

(5
)
Discounted cash flow
Average forward uranium pricing($/pound)(b)
34 - 40
35
Ameren Missouri
Fuel oils
$
5

$
(4
)
Option model
Volatilities(%)(b)
13 - 34
16
 
 
 
 
Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.25 - 0.99
0.63
 
Natural gas
1

(1
)
Option model
Volatilities(%)(b)
27 - 102
40
 
 
 
 
 
Nodal basis($/mmbtu)(c)
(0.3) - (0.2)
(0.2)
 
 
 
 
Discounted cash flow
Nodal basis($/mmbtu)(c)
(0.2) - (0.1)
(0.1)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.27 - 5
1
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
0.43
(e)
 
Power(f)
14

(4
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)
30 - 57
45
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(1,109) - 2,981
474
 
 
 
 
 
Nodal basis($/MWh)(c)
(3) - (1)
(2)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.35
(e)
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
0.43
(e)
 
Uranium
—

(5
)
Discounted cash flow
Average forward uranium pricing($/pound)(b)
34 - 40
35
Ameren Illinois
Power(f)
$
—

$
(120
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(b)
27 - 40
32
 
 
 
 
 
Nodal basis($/MWh)(b)
(6) - (1)
(3)
 
 
 
 
 
Ameren Illinois credit risk(%)(c)(d)
0.43
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 6
5
 
 
 
 
 
Escalation rate(%)(b)(g)
2 - 3
3
 
 
 
 
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)
Not applicable.
(f)
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.
(g)
Escalation rate applies to power prices 2026 and beyond.
The following table describes the valuation techniques and unobservable inputs for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2013:
 
 
Fair Value
 
 
 
Weighted Average
 
 
Assets
Liabilities
Valuation Technique(s)
Unobservable Input
Range
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 the first three months of 2014 or 2013. At March 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 March 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
 
$
1

 
$
—

 
$
5

 
$
6

 
 
Natural gas
 
—

 
6

 
1

 
7

 
 
Power
 
—

 
1

 
14

 
15

 
 
Total derivative assets - commodity contracts
 
$
1

 
$
7

 
$
20

 
$
28

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
2

 
$
—

 
$
—

 
$
2

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
327

 
—

 
—

 
327

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
61

 
—

 
61

 
 
Municipal bonds
 
—

 
2

 
—

 
2

 
 
U.S. treasury and agency securities
 
—

 
94

 
—

 
94

 
 
Asset-backed securities
 
—

 
14

 
—

 
14

 
 
Other
 
—

 
1

 
—

 
1

 
 
Total nuclear decommissioning trust fund
 
$
329

 
$
172

 
$
—

 
$
501

(b) 
 
Total Ameren
 
$
330

 
$
179

 
$
20

 
$
529

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

 
$
—

 
$
5

 
$
6

 
 
Natural gas
 
—

 
1

 
1

 
2

 
 
Power
 
—

 
1

 
14

 
15

 
 
Total derivative assets - commodity contracts
 
$
1

 
$
2

 
$
20

 
$
23

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
2

 
$
—

 
$
—

 
$
2

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
327

 
—

 
—

 
327

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
61

 
—

 
61

 
 
Municipal bonds
 
—

 
2

 
—

 
2

 
 
U.S. treasury and agency securities
 
—

 
94

 
—

 
94

 
 
Asset-backed securities
 
—

 
14

 
—

 
14

 
 
Other
 
—

 
1

 
—

 
1

 
 
Total nuclear decommissioning trust fund
 
$
329

 
$
172

 
$
—

 
$
501

(b) 
 
Total Ameren Missouri
 
$
330

 
$
174

 
$
20

 
$
524

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

 
$
5

 
$
—

 
$
5

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

 
$
—

 
$
4

 
$
4

 
 
Natural gas
 
2

 
34

 
1

 
37

 
 
Power
 
—

 
2

 
124

 
126

 
 
Uranium
 
—

 
—

 
5

 
5

 
 
Total Ameren
 
$
2

 
$
36

 
$
134

 
$
172

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

 
$
—

 
$
4

 
$
4

 
 
Natural gas
 
2

 
5

 
1

 
8

 
 
Power
 
—

 
2

 
4

 
6

 
 
Uranium
 
—

 
—

 
5

 
5

 
 
Total Ameren Missouri
 
$
2

 
$
7

 
$
14

 
$
23

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

 
$
29

 
$
—

 
$
29

 
 
Power
 
—

 
—

 
120

 
120

 
 
Total Ameren Illinois
 
$
—

 
$
29

 
$
120

 
$
149

 
(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

 
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
Derivative assets - commodity contracts(a):
 
 
 
 
 
 
 
 
Missouri
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
Derivative assets - commodity contracts(a):
 
 
 
 
 
 
 
 
Illinois
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
Derivative liabilities - commodity contracts(a):
 
 
 
 
 
 
 
 
Missouri
Fuel oils
 
$
—

 
$
—

 
$
3

 
$
3

 
Natural gas
 
3

 
8

 
—

 
11

 
Power
 
—

 
2

 
2

 
4

 
Uranium
 
—

 
—

 
6

 
6

 
Total Ameren Missouri
 
$
3

 
$
10

 
$
11

 
$
24

Ameren
Derivative liabilities - commodity contracts(a):
 
 
 
 
 
 
 
 
Illinois
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 three months ended March 31, 2014:
  
 
Net derivative commodity contracts
Three Months
 
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
 
(2
)
 
(a)

 
(2
)
Settlements
 
(2
)
 
(a)

 
(2
)
Ending balance at March 31, 2014
$
1

$
(a)

$
1

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

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

$
—

$
—

Purchases
 
—

 
(2
)
 
(2
)
Settlements
 
—

 
2

 
2

Ending balance at March 31, 2014
$
—

$
—

$
—

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

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
19

$
(108
)
$
(89
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(5
)
 
(12
)
 
(17
)
Settlements
 
(5
)
 
—

 
(5
)
Transfers out of Level 3
 
1

 
—

 
1

Ending balance at March 31, 2014
$
10

$
(120
)
$
(110
)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2014
$
(1
)
$
(14
)
$
(15
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
(6
)
$
(a)

$
(6
)
Settlements
 
1

 
(a)

 
1

Ending balance at March 31, 2014
$
(5
)
$
(a)

$
(5
)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2014
$
—

$
(a)

$
—

(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 three months ended March 31, 2013:
  
 
Net derivative commodity contracts
Three Months
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
5

$
(a)

$
5

Purchases
 
1

 
(a)

 
1

Settlements
 
(1
)
 
(a)

 
(1
)
Ending balance at March 31, 2013
$
5

$
(a)

$
5

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

$
2

$
2

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

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
11

$
(111
)
$
(100
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
5

 
14

 
19

Settlements
 
(13
)
 
16

 
3

Transfers into Level 3
 
(2
)
 
—

 
(2
)
Transfers out of Level 3
 
1

 
—

 
1

Ending balance at March 31, 2013
$
2

$
(81
)
$
(79
)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2013
$
(3
)
$
14

$
11

Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
(2
)
$
(a)

$
(2
)
Ending balance at March 31, 2013
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2013
$
—

$
(a)

$
—

(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 shown below. Any reclassifications are reported as transfers out of Level 3 at the fair value measurement reported at the beginning of the period in which the changes occur. For the three months ended March 31, 2014, and 2013, there were no transfers between Level 1 and Level 2 related to derivative commodity contracts. The following table summarizes all transfers between fair value hierarchy levels related to derivative commodity contracts for the three months ended March 31, 2014, and 2013:
  
Three Months
 
2014
2013
Derivative commodity contracts
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Transfers into Level 3 / Transfers out of Level 2 - Power
$
—

$
—

$
—

$
(2
)
$
—

$
(2
)
Transfers out of Level 3 / Transfers into Level 2 - Power
1

—

1

1

—

1

Net fair value of Level 3 transfers
$
1

$
—

$
1

$
(1
)
$
—

$
(1
)
The Ameren Companies’ carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments and are considered to be Level 1 in the fair value hierarchy. Ameren’s and Ameren Missouri’s carrying amounts of investments in debt securities related to the two CTs from the city of Bowling Green and Audrain County approximate fair value. These investments are classified as held-to-maturity. These investments are considered Level 2 in the fair value hierarchy as they are valued based on similar market transactions. The Ameren Companies’ short-term borrowings also approximate fair value because of their short-term nature. Short-term borrowings are considered to be Level 2 in the fair value hierarchy as they are valued based on market rates for similar market transactions. The estimated fair value of long-term debt and preferred stock is based on the quoted market prices for same or similar issuances for companies with similar credit profiles or on the current rates offered to the Ameren Companies for similar financial instruments, which fair value measurement is considered Level 2 in the fair value hierarchy.
The following table presents the carrying amounts and estimated fair values of our long-term debt, capital lease obligations and preferred stock at March 31, 2014, and December 31, 2013:
  
March 31, 2014
 
December 31, 2013
  
Carrying
Amount
 
Fair
Value
 
Carrying
Amount
 
Fair
Value
Ameren:(a)
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
5,874

 
$
6,530

 
$
6,038

 
$
6,584

Preferred stock
142

 
119

 
142

 
118

Ameren Missouri:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
3,758

 
$
4,200

 
$
3,757

 
$
4,124

Preferred stock
80

 
71

 
80

 
71

Ameren Illinois:
 
 
 
 
 
 
 
Long-term debt (including current portion)
$
1,692

 
$
1,903

 
$
1,856

 
$
2,028

Preferred stock
62

 
48

 
62

 
47

(a)
Preferred stock is recorded in “Noncontrolling Interests” on the consolidated balance sheet.
Related Party Transactions
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS
Ameren and its subsidiaries have engaged in, and may in the future engage in, affiliate transactions in the normal course of business. These transactions primarily consist of 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. For a discussion of our material related party agreements, see Note 14 - Related Party Transactions under Part II, Item 8, of the Form 10-K.
Collateral Postings
Under the terms of the Illinois power procurement agreements entered into through an RFP process administered by the IPA, suppliers must post collateral under certain market conditions to protect Ameren Illinois in the event of nonperformance. The collateral postings are unilateral, meaning that only the suppliers would be required to post collateral. Therefore, Ameren Missouri, as a winning supplier in the RFP process, may be required to post collateral to Ameren Illinois. As of March 31, 2014, and December 31, 2013, there were no collateral postings required of Ameren Missouri related to the Illinois power procurement agreements.
The following table presents the impact on Ameren Missouri and Ameren Illinois of related party transactions for the three months ended March 31, 2014, and 2013. It is based primarily on the agreements discussed above and in Note 14 - Related Party Transactions under Part II, Item 8, of the Form 10-K, and the money pool arrangements discussed in Note 3 - Short-term Debt and Liquidity of this report.
  
  
 
  
 
Three Months
Agreement
Income Statement
Line Item
 
  
 
Ameren
Missouri
 
Ameren
Illinois
Ameren Missouri power supply
Operating Revenues
 
2014
$
(b)
$
(a)

agreements with Ameren Illinois
 
 
2013
 
1
 
(a)

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2014
 
5
 
(b)

rent and facility services
 
 
2013
 
5
 
(b)

Total Operating Revenues
 
 
2014
$
5
$
(b)

 
 
 
2013
 
6
 
(b)

Ameren Illinois power supply
Purchased Power
 
2014
$
(a)
$
(b)

agreements with Ameren Missouri
 
 
2013
 
(a)
 
1

Ameren Illinois transmission
Purchased Power
 
2014
 
(a)
 
1

services with ATXI
 
 
2013
 
(a)
 
1

Total Purchased Power
 
 
2014
$
(a)
$
1

 
 
 
2013
 
(a)
 
2

Ameren Services support services
Other Operations and Maintenance
 
2014
$
33
$
27

agreement
 
 
2013
 
31
 
25

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

 
 
 
2013
 
(b)
 
(a)

Total Other Operations and
 
 
2014
$
33
$
27

Maintenance Expenses
 
 
2013
 
31
 
25

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

 
 
 
2013
 
(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, property damage, and terrorism coverage.
Commitments And Contingencies
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES
We are involved in legal, tax and regulatory proceedings before various courts, regulatory commissions, authorities and governmental agencies with respect to matters that arise in the ordinary course of business, some of which involve substantial amounts of money. We believe that the final disposition of these proceedings, except as otherwise disclosed in the notes to our financial statements in this report and in our Form 10-K, will not have a material adverse effect on our results of operations, financial position, or liquidity.
Reference is made to Note 1 - Summary of Significant Accounting Policies, Note 2 - Rate and Regulatory Matters, Note 14 - Related Party Transactions, Note 15 - Commitments and Contingencies and Note 16 - Divestiture Transactions and Discontinued Operations under Part II, Item 8, of the Form 10-K. See also Note 1 - Summary of Significant Accounting Policies, Note 2 - Rate and Regulatory Matters, Note 8 - Related Party Transactions, Note 10 - Callaway Energy Center and Note 12 - 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 March 31, 2014. The property coverage and the nuclear liability coverage must be renewed on April 1 and January 1, respectively, of each year. Both coverages were renewed in 2014.
Type and Source of Coverage
Maximum  Coverages
 
Maximum Assessments
for Single Incidents
 
Public liability and nuclear worker liability:
 
 
 
 
American Nuclear Insurers
$
375

  
$
—

  
Pool participation
13,241

(a) 
128

(b) 
 
$
13,616

(c) 
$
128

  
Property damage:
 
 
 
 
NEIL
$
2,250

(d) 
$
23

(e) 
European Mutual Association for Nuclear Insurance
500

(f) 
—

 
 
$
2,750

 
$
23

 
Replacement power:
 
 
 
 
NEIL
$
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 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. There is a $1.7 billion sublimit for nonradiation events, of which the last $200 million is a shared limit with other generators purchasing this coverage. The $1.7 billion sublimit for nonradiation events was not included with the April 1, 2014 renewal.
(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 at our nuclear energy center. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first eight weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter for a total not exceeding the policy limit of $490 million. Nonradiation events are sub-limited to $327.6 million.
(h)
Provides replacement power cost insurance in the event of a prolonged accidental outage at our nuclear energy center. The coverage commences after the first 52 weeks of insurance coverage from NEIL and is a weekly indemnity of $900,000 for 71 weeks in excess of the $3.6 million per week set forth above. Missouri Energy Risk Assurance Company LLC is an affiliate and has reinsured this coverage with third-party insurance companies. See Note 8 - Related Party Transactions for more information on this affiliate transaction.
The Price-Anderson Act is a federal law that limits the liability for claims from an incident involving any licensed United States commercial nuclear energy center. The limit is based on the number of licensed reactors. The limit of liability and the maximum potential annual payments are adjusted at least every five years for inflation to reflect changes in the Consumer Price Index. The five-year inflationary adjustment was effective September 10, 2013. Owners of a nuclear reactor cover this exposure through a combination of private insurance and mandatory participation in a financial protection pool, as established by the Price-Anderson Act.
Losses resulting from terrorist attacks are covered under NEIL’s policies, subject to an industrywide aggregate policy limit of $3.24 billion within a 12-month period for coverage for such terrorist acts.
If losses from a nuclear incident at the Callaway energy center exceed the limits of, or are not covered by insurance, or if coverage is unavailable, Ameren Missouri is at risk for any uninsured losses. If a serious nuclear incident were to occur, it could have a material adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial position, or liquidity.
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. For a complete listing of our obligations and commitments, see Note 15 - Commitments and Contingencies under Part II, Item 8 of the Form 10-K.
At March 31, 2014, total other obligations related to the procurement of coal, natural gas, nuclear fuel, purchased power, methane gas, equipment and meter reading services, among other agreements, at Ameren, Ameren Missouri and Ameren Illinois were $6,251 million, $4,273 million, and $1,908 million, respectively.
Environmental Matters
We are subject to various environmental laws and regulations enforced by federal, state, and local authorities. From the beginning phases of siting and development to the ongoing operation of existing or new electric generation, transmission and distribution facilities and natural gas storage, transmission and distribution facilities, our activities involve compliance with diverse environmental laws and regulations. These laws and regulations address emissions, discharges to water, water usage, impacts to air, land, and water, and chemical and waste handling. Complex and lengthy processes are required to obtain and renew approvals, permits, or licenses for new, existing or modified facilities. Additionally, the use and handling of various chemicals or hazardous materials require release prevention plans and emergency response procedures.
The EPA is developing environmental regulations that will have a significant impact on the electric utility industry. Over time, compliance with these regulations could be particularly costly for certain companies, including Ameren Missouri, that operate coal-fired energy centers. Significant new rules proposed or promulgated include the regulation of CO2 emissions from new energy centers; revised national ambient air quality standards for ozone, fine particulates, SO2, and NOx emissions; the CSAPR, which requires further reductions of SO2 emissions and NOx emissions from energy centers; a regulation governing management of CCR and coal ash impoundments; the MATS, which require reduction of emissions of mercury, toxic metals, and acid gases from energy centers; revised NSPS for particulate matter, SO2, and NOx emissions from new sources; new effluent standards applicable to waste water discharges from energy centers and new regulations under the Clean Water Act that could require significant capital expenditures, such as modifications to water intake structures or new cooling towers at our energy centers. The EPA is expected to propose CO2 standards for existing fossil fuel-fired electric generation units in the future. These new and proposed regulations, if adopted, may be challenged through litigation, so their ultimate implementation, as well as the timing of any such implementation, is uncertain. Although many details of these future regulations are unknown, the combined effects of the new and proposed environmental regulations may result in significant capital expenditures and increased operating costs over the next five to ten years for Ameren and Ameren Missouri. Compliance with these environmental laws and regulations could be prohibitively expensive or could result in the closure or alteration of the operation of some of our energy centers. Ameren and Ameren Missouri would expect these costs to be recoverable through rates, but the nature and timing of costs, as well as the applicable regulatory framework, could result in regulatory lag.
As of March 31, 2014, Ameren and Ameren Missouri estimate capital expenditure investments of $275 million to $350 million over the next five years to comply with existing environmental regulations. This estimate assumes that CCR will continue to be regulated as nonhazardous. This estimate does not include the impacts of regulations proposed by the EPA under the Clean Water Act regarding cooling water intake structures or the impact of the proposed effluent standards applicable to steam-electric generating units, as the technology requirements of these final rules are not yet known. Considerable uncertainty remains in this estimate. The actual amount of capital expenditure investments to comply with existing environmental regulations may vary substantially from the above estimate due to uncertainty as to the precise compliance strategies that will be used and their ultimate cost, among other things.
Ameren Missouri's current environmental compliance plan for air emissions includes burning ultra-low-sulfur coal and installing new or optimizing existing pollution control equipment. Ameren Missouri has two scrubbers at its Sioux energy center, which are used to reduce SO2 emissions and other pollutants. Currently, Ameren Missouri's compliance plan assumes the installation of additional controls including mercury control technology and electrostatic precipitator upgrades at multiple energy centers within its coal-fired fleet during the next five years. However, Ameren Missouri is currently evaluating its operations and options to determine how to comply with the 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 ten years.
Environmental compliance costs at some of Ameren Missouri's energy centers could be prohibitive and additional capital investment or continued operations unwarranted. Ameren Missouri's capital expenditures and other costs are subject to MoPSC prudence reviews, which could result in cost disallowances as well as regulatory lag.
The following sections describe the more significant environmental laws and rules that affect or could affect our operations.
Clean Air Act
Both federal and state laws require significant reductions in SO2 and NOx emissions that result from burning fossil fuels. In 2005, the EPA issued regulations with respect to SO2 and NOx emissions (the CAIR). In December 2008, the United States Court of Appeals for the District of Columbia Circuit found various aspects of the law to be unlawful and remanded the CAIR to the EPA for further action, but allowed the CAIR's cap-and-trade programs to remain effective until they are replaced by the EPA. In July 2011, the EPA issued the CSAPR as the CAIR replacement. The CSAPR regulations were vacated by the United States Court of Appeals for the District of Columbia Circuit. The EPA appealed to the United States Supreme Court. In April 2014, the United States Supreme Court reversed the decision of the United States Court of Appeals for the District of Columbia Circuit’s decision and upheld the CSAPR. Ameren and Ameren Missouri are continuing to review the United States Supreme Court’s decision and expect the EPA to issue guidance in the near future on implementing the 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. Assuming the EPA does not revise the emission reductions previously included in the CSAPR, 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 utilize chemicals to lower its emissions at one or more of its energy centers for compliance with the CSAPR. These higher operations and maintenance costs will 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 require emission reductions for mercury and other hazardous air pollutants, such as acid gases, toxic metals, and hydrogen chloride emissions. The MATS do not require a specific control technology to achieve the emission reductions. The MATS will apply to each unit at a coal-fired power plant; however in certain cases, emission compliance can be achieved by averaging emissions from similar electric generating units at the same power plant. Compliance is required by April 2015 or, with a case-by-case extension, by April 2016. Ameren Missouri's Labadie and Meramec energy centers requested and were granted extensions to April 2016 to comply with the MATS.
Emission Allowances
The Clean Air Act created marketable commodities called emission allowances under the acid rain program, the NOx budget trading program, the CAIR and the CSAPR. Ameren Missouri expects to have enough allowances for 2014 to avoid making external purchases to comply with the CAIR and the acid rain program. Ameren and Ameren Missouri are continuing to review the United States Supreme Court’s decision upholding the CSAPR and will review any guidance the EPA may issue regarding implementing the CSAPR and its emission allowance program.
Greenhouse Gas Regulation
In December 2009, the EPA issued its “endangerment finding” under the Clean Air Act, which stated that greenhouse gas emissions, including CO2, endanger human health and welfare and that emissions of greenhouse gases from motor vehicles contribute to that endangerment. In March 2010, the EPA issued a determination that greenhouse gas emissions from stationary sources, such as power plants, would be subject to regulation under the Clean Air Act effective the beginning of 2011. As a result of these actions, we are required to consider the emissions of greenhouse gases in any air permit application.
Recognizing the difficulties presented by regulating at once virtually all emitters of greenhouse gases, the EPA issued the “Tailoring Rule,” which established new higher emission thresholds beginning in January 2011 for regulating greenhouse gas emissions from stationary sources, such as power plants. The rule requires any source that already has an operating permit to have greenhouse-gas-specific provisions added to its permit upon renewal. Currently, all Ameren energy centers have operating permits that have been modified to address greenhouse gas emissions. The Tailoring Rule also provides that if projects performed at major sources or new major sources result in an increase in emissions of greenhouse gases over an applicable annual threshold, such projects could trigger permitting requirements under the NSR programs and the application of best available control technology to control greenhouse gas emissions. In June 2012, the United States Court of Appeals for the District of Columbia Circuit upheld the Tailoring Rule. Industry groups and a coalition of states filed petitions in April 2013 requesting that the United States Supreme Court review the circuit court's decision. In October 2013, the United States Supreme Court agreed to consider whether the Clean Air Act authorizes the EPA to regulate emissions of greenhouse gases from stationary sources, including power plants, as a result of its determination to regulate greenhouse gas emissions from motor vehicles. A ruling is expected in 2014.
In June 2013, the Obama administration announced that it had directed the EPA to set CO2 emissions standards for both new and existing power plants. The EPA published proposed regulations in January 2014 that would set revised CO2 emissions standards for new electricity generating units. The proposed standards would establish separate emissions limits for new natural gas-fired plants and new coal-fired plants. In addition, the Obama administration directed the EPA to propose a CO2 emissions standard for existing power plants by June 2014 and to finalize such standard by June 2015. Currently, Ameren and Ameren Missouri are unable to predict the outcome of these rulemakings or impacts of such future regulations if and when they become effective.  
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 our energy centers, as the expected return from these investments, at current market prices for energy and capacity, might not justify the required capital expenditures or their continued operation, which could result in the impairment of long-lived assets if costs are not recovered through rates. Mandatory limits on the emission of greenhouse gases could increase costs for our 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 cost recovery in rates of these compliance costs. Ameren's and Ameren Missouri's earnings may benefit from increased investment to the extent the investments comply with greenhouse gas limitations and are reflected and recovered timely in rates.
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. The trial in this matter is currently scheduled to begin in 2015. Ameren Missouri believes its defenses are meritorious and will defend itself vigorously. However, there can be no assurances that it will be successful in its efforts.
Ultimate resolution of 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 March 2011, the EPA announced a proposed rule applicable to cooling water intake structures at existing power plants. The proposed rule would impose standards for reducing the mortality of aquatic organisms impinged on the plant's intake screens or entrained through the plant's cooling water system. All coal-fired, nuclear, and combined cycle energy centers at Ameren Missouri with cooling water systems are subject to this proposed rule. The EPA has stated that it will finalize the rule in May 2014. When finalized, the rule could have an adverse effect on our results of operations, financial position, and liquidity if its implementation requires the installation of cooling towers or extensive modifications to the cooling water systems at our energy centers and if those investments are not recovered timely in rates.
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, however, the final rule will determine the schedule. The EPA expects to issue final guidelines by September 30, 2015.
Ash Management
In May 2010, the EPA announced proposed new regulations regarding the management and disposal of CCR, which could affect future disposal and handling costs at our energy centers. Those proposed regulations include two options for managing CCRs, under either solid or hazardous waste regulations, but either alternative would allow for some continued beneficial uses, such as recycling of CCR without classifying it as waste. The EPA announced that its April 2013 proposed revisions to the effluent limitations applicable to steam electric generating units would apply to ash ponds and CCR management and that it intended to align this proposal with the CCR rules when finalized. The EPA is expected to issue regulations describing how it will regulate CCR by December 2014. Ameren Missouri is currently evaluating all of the proposed regulations to determine whether current management of CCR, including beneficial reuse, and the use of the ash ponds should be altered. Ameren Missouri is evaluating the potential costs associated with compliance with the proposed regulation of CCR impoundments and landfills, which could be material, if such regulations are adopted.
Remediation
We are involved in a number of remediation actions to clean up sites impacted by hazardous substances as required by federal and state law. Such statutes require that responsible parties fund remediation actions regardless of their degree of fault, the legality of original disposal, or the ownership of a disposal site. Ameren Missouri and Ameren Illinois have each been identified by the federal or state governments as a potentially responsible party at several contaminated sites.
As of March 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. Based on current estimated plans, Ameren Illinois could substantially conclude remediation efforts at most of these sites by 2018. The ICC permits Ameren Illinois to recover remediation and litigation costs associated with its former MGP sites from its electric and natural gas utility customers through environmental adjustment rate riders. To be recoverable, such costs must be prudently incurred. Costs are subject to annual review by the ICC.
As of March 31, 2014, Ameren Missouri has one remaining former MGP site for which remediation is scheduled. Remediation is complete at the other Ameren Missouri former MGP sites. Ameren Missouri does not currently have a rate rider mechanism that permits it to recover from utility customers remediation costs associated with MGP sites.

The following table presents, as of March 31, 2014, the estimated obligation to complete the remediation of these former MGP sites:
  
Estimate
 
Recorded
  Liability(a)
  
Low
 
High
 
Ameren
$
269

 
$
345

 
$
269

Ameren Missouri
3

 
4

 
3

Ameren Illinois
266

 
341

 
266

(a)
Recorded liability represents the estimated minimum probable obligations, 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 used an off-site landfill, which Ameren Illinois did not own, in connection with the former operation of an energy center. Ameren Illinois could be required to perform certain maintenance activities associated with that landfill. As of March 31, 2014, Ameren Illinois estimated the obligation related to the cleanup 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 March 31, 2014, Ameren Illinois recorded a liability of $0.8 million to represent its estimate of the obligation for these sites.
Ameren Missouri is investigating and addressing two waste sites in Missouri as a result of federal agency mandates. One of the cleanup sites is a former coal tar distillery located in St. Louis, Missouri. In 2008, the EPA issued an administrative order to Ameren Missouri pertaining to this distillery operated by Koppers Company or its predecessor and successor companies. While Ameren Missouri is the current owner of the site, it did not conduct any of the manufacturing operations involving coal tar or its byproducts. Ameren Missouri, along with two other potentially responsible parties, are performing a site investigation. As of March 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's other active federal agency-mandated cleanup site in Missouri is in Cape Girardeau. Ameren Missouri was a customer of an electrical equipment repair and disposal company that previously operated a facility at this site. A trust was established in the early 1990s by several businesses and governmental agencies to fund the investigation and cleanup of this site, which was completed in 2005. Ameren Missouri anticipates that this trust fund will be sufficient to complete the remaining adjacent off-site cleanup, and therefore, Ameren Missouri believes it has no liability at March 31, 2014, for this site.
Ameren Missouri also has a federal agency mandate to complete an investigation for a site in Illinois. In 2000, the EPA notified Ameren Missouri and numerous other companies, including Solutia, that former landfills and lagoons in Sauget, Illinois, may contain soil and groundwater contamination. These sites are known as Sauget Area 2. From about 1926 until 1976, Ameren Missouri operated an energy center adjacent to Sauget Area 2. Ameren Missouri currently owns a parcel of property that was once used as a landfill. Under the terms of an Administrative Order on Consent, Ameren Missouri joined with other potentially responsible parties to evaluate the extent of potential contamination with respect to Sauget Area 2.
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 March 31, 2014, Ameren Missouri estimated its obligation related to Sauget Area 2 at $1 million to $2.5 million. During the first quarter of 2014, Ameren Missouri recorded an additional liability of $0.7 million, to reflect the negotiations with the potentially responsible parties, for a total liability of $1 million to represent its estimated minimum obligation.
In December 2012, Ameren Missouri signed an administrative order with the EPA and agreed to investigate soil and groundwater conditions at an Ameren Missouri owned substation in St. Charles, Missouri. As of March 31, 2014, Ameren Missouri estimated the obligation related to the cleanup at $1.6 million to $4.5 million. Ameren Missouri recorded a liability of $1.6 million to represent its estimated minimum obligation for this site, as no other amount within the range was a better estimate.
Our operations or those of our predecessor companies involve the use of, disposal of, and in appropriate circumstances, the cleanup of substances regulated under environmental laws. We are unable to determine whether such practices will result in future environmental commitments or will affect our results of operations, financial position, or liquidity.
Pumped-storage Hydroelectric Facility Breach
In December 2005, there was a breach of the upper reservoir at Ameren Missouri's Taum Sauk pumped-storage hydroelectric energy center. This resulted in significant flooding in the local area, which damaged a state park. The rebuilt Taum Sauk energy center became fully operational in April 2010.
Ameren Missouri had liability insurance coverage for the Taum Sauk incident, subject to certain limits and deductibles. As of March 31, 2014, Ameren Missouri had an insurance receivable balance of $68 million.
In June 2010, Ameren Missouri sued an insurance company that was providing Ameren Missouri with liability coverage on the date of the Taum Sauk incident. In the litigation, filed in the United States District Court for the Eastern District of Missouri, Ameren Missouri claimed that the insurance company breached its duty to indemnify Ameren Missouri for the losses resulting from the incident. In January 2011, the district court ruled that the parties must first pursue alternative dispute resolution and enforced the forum selection clause of their coverage agreement. The forum selection clause requires use of New York law and effectively requires mandatory arbitration. Ameren Missouri appealed the January 2011 ruling to the United States Court of Appeals for the Eighth Circuit. In August 2012, the court of appeals remanded the case to the district court for consideration of whether Missouri public policy voids the forum selection clause. In September 2013, the district court ruled that Missouri public policy voids the forum selection clause.
Separately, in April 2012, Ameren Missouri sued a second insurance company that was providing Ameren Missouri with liability coverage on the date of the Taum Sauk incident. In the April 2012 litigation, which is pending in the United States District Court for the Eastern District of Missouri, Ameren Missouri claimed the insurance company breached its duty to indemnify Ameren Missouri for the losses resulting from the incident. The insurance company filed a motion to compel arbitration, which the district court denied. In April 2013, the United States Court of Appeals for the Eighth Circuit affirmed the district court’s denial of the insurer’s motion and remanded the case to the district court.
Ameren's and Ameren Missouri's results of operations, financial position and liquidity could be adversely affected if Ameren Missouri's remaining liability insurance claims are not paid by insurers.
Asbestos-related Litigation
Ameren, Ameren Missouri and Ameren Illinois have been named, along with numerous other parties, in a number of lawsuits filed by plaintiffs claiming varying degrees of injury from asbestos exposure at our present or former energy centers. Most have been filed in the Circuit Court of Madison County, Illinois. The total number of defendants named in each case varies, with the average number of parties being 85 as of March 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 March 31, 2014:
Ameren
 
Ameren
Missouri
 
Ameren
Illinois
 
Total(a)
1
 
47
 
56
 
71
(a)
Total does not equal the sum of the subsidiary unit lawsuits because some of the lawsuits name multiple Ameren entities as defendants.
At March 31, 2014, Ameren, Ameren Missouri and Ameren Illinois had liabilities of $12 million, $5 million, and $7 million, respectively, recorded to represent their best estimate of their obligations related to asbestos claims.
Ameren Illinois has a tariff rider to recover the costs of IP asbestos-related litigation claims, subject to the following terms: 90% of cash expenditures in excess of the amount included in base electric rates are to be recovered from a trust fund that was established when Ameren acquired IP. At March 31, 2014, the trust fund balance was $23 million, including accumulated interest. If cash expenditures are less than the amount in base rates, Ameren Illinois will contribute 90% of the difference to the trust fund. Once the trust fund is depleted, 90% of allowed cash expenditures in excess of base rates will be recovered through charges assessed to customers under the tariff rider. The rider will permit recovery from customers within IP’s historical service territory.
Ameren Illinois Municipal Taxes
Ameren Illinois received tax liability notices from the city of O'Fallon, Illinois, relating to prior-period electric and natural gas municipal taxes. The city alleges that Ameren Illinois failed to collect prior-period taxes from more than 2,400 accounts, primarily in annexed areas, for the period 2004 through 2012. In July 2013, the O’Fallon city administrator issued an order stating that Ameren Illinois was liable to the city of O’Fallon for $4 million. In August 2013, Ameren Illinois filed an appeal and a stay of the O’Fallon city administrator’s order to the Circuit Court of St. Clair County. In addition, in December 2012, the city of Peoria issued a tax liability notice alleging that Ameren Illinois failed to collect prior-period municipal taxes from certain accounts. In September 2013, a hearing officer issued an order stating that Ameren Illinois was liable to the city of Peoria for $0.5 million. Ameren Illinois filed an appeal and a stay of the order to the Circuit Court of Peoria County. Ameren Illinois believes its defenses to the allegations are meritorious. As of March 31, 2014, Ameren Illinois estimated its obligation at $1 million to $5 million. Ameren Illinois recorded a liability of $1 million, which reflects potential settlements with both of the cities.
In addition, at the end of 2012, five other cities issued tax liability notices alleging that Ameren Illinois failed to collect an immaterial amount of taxes from certain accounts.
Callaway Energy Center
CALLAWAY ENERGY CENTER
CALLAWAY ENERGY CENTER
Under the NWPA, the DOE is responsible for disposing of spent nuclear fuel from the Callaway energy center and other commercial nuclear energy centers. Under the NWPA, Ameren and other utilities that own and operate those energy centers are responsible for paying the disposal costs. The NWPA established the fee that these utilities pay the federal government for disposing of the spent nuclear fuel at one mill, or one-tenth of one cent, for each kilowatthour generated by those plants and sold. The NWPA also requires the DOE to review the nuclear waste fee against the cost of the nuclear waste disposal program and to propose to the United States Congress any fee adjustment necessary to offset the costs of the program. As required by the NWPA, Ameren Missouri and other utilities have entered into standard contracts with the federal government. The government, represented by the DOE, is responsible for implementing these provisions of the NWPA. Consistent with the NWPA and its standard contract, Ameren Missouri collects one mill from its electric customers for each kilowatthour of electricity that it generates and sells from its Callaway energy center.
Although both the NWPA and the standard contract stated that the federal government would begin to dispose of spent nuclear fuel by 1998, the federal government is not meeting its disposal obligation. Ameren Missouri has sufficient installed capacity at the Callaway energy center to store its spent nuclear fuel generated through 2020, and it has the capability for additional storage capacity for spent nuclear fuel generated through the end of the energy center’s current license. The DOE's delay in carrying out its obligation to dispose of spent nuclear fuel from the Callaway energy center is not expected to adversely affect the continued operations of the energy center.
In January 2009, the federal government announced that a spent nuclear fuel repository at Yucca Mountain, Nevada was unworkable. The federal government took steps to terminate the Yucca Mountain program, while acknowledging its continuing obligation to dispose of utilities’ spent nuclear fuel. In January 2013, the DOE issued its plan for the management and disposal of spent nuclear fuel. The DOE's plan calls for a pilot interim storage facility to begin operation with an initial focus on accepting spent nuclear fuel from shutdown reactor sites by 2021. By 2025, a larger interim storage facility would be available, co-located with the pilot facility. The plan also proposes to site a permanent geological repository by 2026, to characterize the site and to design and to license the repository by 2042, and to begin operation by 2048.
In view of the federal government's efforts to terminate the Yucca Mountain program, the Nuclear Energy Institute, a number of individual utilities, and the National Association of Regulatory Utility Commissioners sued the DOE in the United States Court of Appeals for the District of Columbia Circuit, seeking the suspension of the one mill nuclear waste fee, alleging that the DOE failed to undertake an appropriate fee adequacy review reflecting the current unsettled state of the nuclear waste program. In a June 2012 decision, the court ruled that the DOE's fee adequacy review was legally inadequate and remanded the matter to the DOE. Although the court ruled it has the power to direct the DOE to suspend the fee, the court decided that it was premature to do so. Instead, the court ordered the DOE to provide within six months a revised assessment of the amount that should be collected. In January 2013, the DOE issued the revised assessment required by the court. The DOE determined that “neither insufficient nor excess revenues are being collected,” and it proposed no adjustment to the one mill nuclear waste fee. In November 2013, the court rejected the DOE's revised assessment and ordered the DOE to submit a proposal to the United States Congress to reduce the fee to zero. In January 2014, the DOE submitted a proposal to the United States Congress to reduce the fee to zero. Absent further action by the DOE, the fee reduction is expected to take effect during the second quarter of 2014. The nuclear waste fee is included in Ameren Missouri’s FAC. Therefore, if the fee is reduced to zero, the cost reduction will be passed on to electric utility customers with no material effect on Ameren’s and 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. It sought reimbursement for the cost of reracking the Callaway energy center’s spent fuel pool, as well as certain NRC fees, and Missouri ad valorem taxes that Ameren Missouri would not have incurred had the DOE performed its contractual obligations. In June 2011, the parties entered into a settlement agreement that provides for annual recovery of additional spent fuel storage and related costs incurred from 2010 through 2013 with the ability to extend the recovery period as mutually agreed to by the parties. The parties have agreed in principle to extend the recovery period through 2016. In March 2014, Ameren Missouri submitted its 2013 costs to the DOE for reimbursement under the settlement agreement. Ameren Missouri expects to receive the 2013 cost reimbursement of approximately $15 million during the third quarter of 2014. This reimbursement is included in "Miscellaneous accounts and notes receivable" on Ameren’s and Ameren Missouri’s March 31, 2014 and December 31, 2013 balance sheets. Included in these reimbursements are costs related to a dry spent fuel storage facility Ameren Missouri is constructing at its Callaway energy center. Ameren Missouri intends to begin transferring spent fuel assemblies to this facility in 2015. Until the facility is completed, Ameren Missouri will apply for reimbursement from the DOE for the cost to construct the dry spent fuel storage facility along with related allowable costs.
In December 2011, Ameren Missouri submitted a license extension application to the NRC to extend its Callaway energy center's operating license from 2024 to 2044. There is no deadline by which the NRC must act on this application. Among the rules that the NRC has historically relied upon in approving license extensions are rules dealing with the storage of spent nuclear fuel at the reactor site and with the NRC's confidence that permanent disposal of spent nuclear fuel will be available when needed. In a June 2012 decision, the United States Court of Appeals for the District of Columbia Circuit vacated these rules and remanded the case to the NRC, holding that the NRC's obligations under the National Environmental Policy Act required a more thorough environmental analysis in support of the NRC's waste confidence decision. In June 2012, a number of groups petitioned the NRC to suspend final licensing decisions in certain NRC licensing proceedings, including the Callaway license extension, until the NRC completed its proceedings on the vacated rules. In August 2012, the NRC stated that it would not issue licenses dependent on the vacated rules until it appropriately addressed the court's remand. In September 2012, the NRC directed its staff to issue, within two years, a generic environmental impact statement and a final rule to address the court's ruling. The NRC also stated that a site-specific analysis of these issues could be conducted in rare circumstances. If the Callaway energy center's license is extended, additional spent fuel storage will be required.
Electric utility rates charged to customers provide for the recovery of the Callaway energy center's decommissioning costs, which include decontamination, dismantling, and site restoration costs, over an assumed 40-year life of the nuclear center, ending with the expiration of the energy center's current operating license in 2024. 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. Decommissioning costs are included in the costs of service used to establish electric rates for Ameren Missouri's customers. These costs amounted to $7 million in each of the years 2013, 2012, and 2011. Every three years, the MoPSC requires Ameren Missouri to file an updated cost study and funding analysis for decommissioning its Callaway energy center. Electric rates may be adjusted at such times to reflect changed estimates. The last cost study and funding analysis were filed with the MoPSC in September 2011. In October 2012, the MoPSC issued an order approving the stipulation and agreement between Ameren Missouri and the MoPSC staff that maintained the current rate of deposits to the trust fund and the rate of return assumptions used in the analysis. If Ameren Missouri's operating license extension application is approved by the NRC, a revised funding analysis will be prepared, and the rates charged to customers will be adjusted accordingly to reflect the operating license extension at the time the next triennial cost study and funding analysis is approved by the MoPSC. 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 for additional information related to the Callaway energy center.
Retirement Benefits
RETIREMENT BENEFITS
RETIREMENT BENEFITS
Ameren’s pension and postretirement plans are funded in compliance with income tax regulations and to meet federal funding or regulatory requirements. As a result, Ameren expects to fund its pension plans at a level equal to the greater of the pension expense or the legally required minimum contribution. Considering Ameren’s assumptions at March 31, 2014, the plan’s estimated investment performance through March 31, 2014, and Ameren’s pension funding policy, Ameren expects to make annual contributions of $20 million to $100 million in each of the next five years, with aggregate estimated contributions of $270 million. These amounts are estimates which may change with actual investment performance, changes in interest rates, any pertinent changes in government regulations, and any voluntary contributions. Our policy for postretirement benefits is primarily to fund the voluntary employees’ beneficiary association trusts to match the annual postretirement expense.
The following table presents the components of the net periodic benefit cost for Ameren’s pension and postretirement benefit plans for the three months ended March 31, 2014, and 2013:
  
Pension Benefits
 
Postretirement Benefits
 
Three Months
 
Three Months
  
2014
 
2013
 
2014
 
2013
Service cost
$
21

 
$
24

 
$
5

 
$
6

Interest cost
49

 
40

 
13

 
12

Expected return on plan assets
(57
)
 
(54
)
 
(16
)
 
(16
)
Amortization of:
 
 
 
 
 
 
 
Prior service cost (benefit)
—

 
(1
)
 
(1
)
 
(1
)
Actuarial loss
12

 
22

 
(1
)
 
2

Net periodic benefit cost
$
25

 
$
31

 
$
—

 
$
3


Ameren Missouri and Ameren Illinois are responsible for their respective shares of Ameren’s pension and postretirement costs. The following table presents the pension costs and the postretirement benefit costs incurred for the three months ended March 31, 2014, and 2013:
  
Pension Costs
Postretirement Costs
 
Three Months
 
Three Months
  
2014
 
2013
 
2014
 
2013
Ameren Missouri
$
17

 
$
18

 
$
1

 
$
2

Ameren Illinois
8

 
10

 
(1
)
 
1

Other
—

 
3

 
—

 
—

Ameren(a)
$
25

 
$
31

 
$
—

 
$
3

(a)
Includes amounts for Ameren registrants and nonregistrant subsidiaries.
Divestiture Transactions and Discontinued Operations (Notes)
DIVESTITURE TRANSACTIONS AND DISCONTINUED OPERATIONS
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. The transaction agreement with IPH provides that if the Elgin, Gibson City, and Grand Tower gas-fired energy centers are subsequently sold to a third party and Medina Valley receives proceeds within two years of the closing of the New AER divestiture, Medina Valley will pay Genco any proceeds from such sale, net of taxes and other expenses, in excess of the amounts previously paid to Genco, which totaled $137.5 million.
On January 31, 2014, Medina Valley completed the sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital for a total purchase price of $168 million, before consideration of a net working capital adjustment. The agreement with Rockland Capital required $17 million of the purchase price to be held in escrow until the two-year anniversary of the closing of the sale to fund certain indemnity obligations, if any, of Medina Valley. The Rockland Capital escrow receivable balance is reflected on Ameren's March 31, 2014 consolidated balance sheet in "Other assets." The corresponding payable due to Genco is reflected on Ameren's March 31, 2014 consolidated balance sheet in "Other deferred credits and liabilities." An immaterial net working capital adjustment with Rockland Capital is expected to be finalized during the second quarter of 2014. 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
New AER and the Elgin, Gibson City, Grand Tower, Meredosia, and Hutsonville energy centers have been classified collectively in Ameren’s consolidated financial statements as discontinued operations for all periods presented in this report. The disposal groups have been aggregated in the disclosures below. See Note 16 - Divestiture Transactions and Discontinued Operations under Part II, Item 8, of the Form 10-K for additional information related to disposal groups. The following table presents the components of discontinued operations in Ameren's consolidated statement of income (loss) for the three months ended March 31, 2014, and 2013:
 
Three months
 
 
2014
 
2013
 
Operating revenues
$
1

 
$
264

 
Operating expenses
(2
)
 
(415
)
(a) 
Operating loss
(1
)
 
(151
)
 
Other loss
—

 
(2
)
 
Interest charges
—

 
(11
)
 
Loss before income taxes
(1
)
 
(164
)
 
Income tax expense
—

 
(35
)
 
Loss from discontinued operations, net of taxes
$
(1
)
 
$
(199
)
 

(a)
Included a noncash pretax asset impairment charge of $155 million, to reduce the carrying value of the New AER disposal group to its estimated fair value less cost to sell.
Ameren recorded a pretax charge to earnings of $155 million for the three months ended March 31, 2013, to reduce the carrying value of the New AER disposal group to its estimated fair value less cost to sell. Also during the three months ended March 31, 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, when it became apparent that the temporary difference would reverse. This change in basis resulted in a discontinued operations deferred tax expense of $98 million, which was partially offset by the then-expected tax benefits of $63 million related to the pretax loss from discontinued operations including the impairment charge, during the three months ended March 31, 2013.
During the three months ended March 31, 2014, Ameren recorded adjustments for its estimate of the New AER net working capital adjustment and for certain contingent liabilities associated with the New AER divestiture to IPH. Ameren also recognized the operating revenues and operating expenses associated with the Elgin, Gibson City, and Grand Tower energy centers prior to the completion of their sale to Rockland Capital on January 31, 2014. The operating expenses associated with the abandoned Meredosia and Hutsonville energy centers were also included in discontinued operations. The aggregate result of these items was a $1 million loss from discontinued operations during the three months ended March 31, 2014.
Ameren and IPH are in the process of finalizing the net working capital adjustment. Additionally, the final tax basis of the AER disposal group and the related tax benefit resulting from the transaction agreement, as amended, with IPH are dependent upon the resolution of tax matters under audit, including the adoption of recently issued guidance from the IRS related to tangible property repairs and other matters. As a result, tax expense and benefits ultimately realized in discontinued operations may differ materially from those recorded as of March 31, 2014.

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 March 31, 2014, and December 31, 2013:
 
March 31, 2014
 
December 31, 2013
Assets of discontinued operations
 
 
 
Cash and cash equivalents
$
—

 
$
—

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
$
2

 
$
5

Asset retirement obligations(b)
31

 
40

Total liabilities of discontinued operations
$
33

 
$
45


(a)
Balances primarily consist of deferred income tax assets related to the abandoned Meredosia and Hutsonville energy centers.
(b)
Includes AROs associated with the abandoned Meredosia and Hutsonville energy centers of $31 million at March 31, 2014, and December 31, 2013.
Pursuant to the IPH transaction agreement, as amended, Ameren is obligated to pay up to $34 million for certain contingent liabilities. Of these liabilities, $29 million were included in "Other deferred credits and liabilities" and $5 million were included in "Accounts and wages payable" on Ameren's March 31, 2014 consolidated balance sheet.
The note receivable from Marketing Company related to the cash collateral support provided to New AER was $27 million and $18 million at March 31, 2014, and December 31, 2013, respectively, and was reflected on Ameren's consolidated balance sheet in "Other assets." This receivable to Ameren is due, with interest, on December 2, 2015, or sooner as cash collateral requirements are reduced. This cash collateral support is part of Ameren’s obligation to provide credit support to New AER until December 2, 2015, as discussed below.
Ameren Guarantees and Letters of Credit
The transaction agreement, as amended, requires Ameren (parent) 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 (parent) pursuant to which Dynegy will, among other things, guarantee IPH's indemnification obligations until December 2, 2015.
At March 31, 2014, Ameren had a total of $184 million in guarantees outstanding for New AER, which included:
•
$171 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 March 31, 2014, Ameren would have been required under its guarantees to provide $17 million to the counterparties.
•
$13 million related to requirements for leasing agreements and potential environmental obligations.
Additionally, at March 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 was probable as of March 31, 2014.
Segment Information
SEGMENT INFORMATION
SEGMENT INFORMATION
Ameren has two reportable segments: Ameren Missouri and Ameren Illinois. The Ameren Missouri segment for both Ameren and Ameren Missouri includes all of the operations of Ameren Missouri’s business as described in Note 1 - Summary of Significant Accounting Policies. The Ameren Illinois segment for both Ameren and Ameren Illinois includes all of the operations of Ameren Illinois’ business as described in Note 1 - Summary of Significant Accounting Policies. The category called Other primarily includes Ameren parent company activities, Ameren Services, and ATXI. In 2013, the Other category also included certain corporate activities previously included in the Merchant Generation segment.
The following table presents information about the reported revenues and specified items reflected in Ameren’s net income attributable to Ameren Corporation from continuing operations for the three months ended March 31, 2014, and 2013, and total assets in continuing operations as of March 31, 2014, and December 31, 2013.
Three Months
Ameren
Missouri
 
Ameren
Illinois
 
Other
 
Intersegment
Eliminations
 
Ameren
 
2014
 
 
 
 
 
 
 
 
 
 
External revenues
$
811

 
$
774

 
$
9

 
$
—

 
$
1,594

 
Intersegment revenues
6

 
—

 
1

 
(7
)
 
—

 
Net income (loss) attributable to Ameren Corporation from continuing operations
47

 
53

 
(3
)
 
—

 
97

 
2013
 
 
 
 
 
 
 
 
 
 
External revenues
$
789

 
$
684

 
$
2

 
$
—

 
$
1,475

 
Intersegment revenues
7

 
—

 
2

 
(9
)
 
—

 
Net income (loss) attributable to Ameren Corporation from continuing operations
40

 
31

 
(17
)
 
—

 
54

 
As of March 31, 2014:
 
 
 
 
 
 
 
 
 
 
Total assets
$
12,948

 
$
7,640

 
$
898

 
$
(335
)
 
$
21,151

(a) 
As of December 31, 2013:
 
 
 
 
 
 
 
 
 
 
Total assets
$
12,904

 
$
7,454

 
$
752

 
$
(233
)
 
$
20,877

(a) 
(a)    Excludes total assets from discontinued operations of $15 million and $165 million as of March 31, 2014, and December 31, 2013, respectively.
Summary Of Significant Accounting Policies (Policies)
Consolidation 
The financial statements of Ameren are prepared on a consolidated basis, and therefore include the accounts of its majority-owned subsidiaries. All significant intercompany transactions have been eliminated. Ameren Missouri and Ameren Illinois have no subsidiaries, and therefore their financial statements are not prepared on a consolidated basis. 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. The results of operations of an interim period may not give a true indication of results that may be expected for a full year. These financial statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K.
Earnings Per Share 
There were no material differences between Ameren’s basic and diluted earnings per share amounts for the three months ended March 31, 2014, and 2013, caused by the assumed settlement of performance share units. The number of dilutive performance share units had an immaterial impact on earnings per share.
Stock-based Compensation 
Ameren’s long-term incentive plan available for eligible employees, the 2006 Omnibus Incentive Compensation Plan (2006 Plan), was replaced prospectively for new grants only by the 2014 Omnibus Incentive Compensation Plan (2014 Plan) effective April 24, 2014. The 2014 Plan provides for a maximum of 8 million common shares to be available for grant to eligible employees and directors, and retains many of the features of the 2006 Plan. The 2014 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.
Intangible Assets 
Ameren and Ameren Missouri classify renewable energy credits and emission allowances as intangible assets. Ameren Illinois consumes renewable energy credits as they are purchased through the IPA procurement process and expenses them immediately. We evaluate intangible assets for impairment if events or changes in circumstances indicate that their carrying amount might be impaired.
At March 31, 2014, Ameren’s and Ameren Missouri’s intangible assets consisted of renewable energy credits obtained through wind and solar power purchase agreements. The book value of Ameren’s and Ameren Missouri’s renewable energy credits was $17 million each at March 31, 2014. The book value of Ameren’s and Ameren Missouri’s renewable energy credits was $22 million each at December 31, 2013.
Ameren Missouri’s and Ameren Illinois’ renewable energy credits and Ameren Missouri’s emission allowances are charged to “Purchased power” expense and “Fuel” expense, respectively, as they are used in operations.
Excise Taxes 
Excise taxes levied on us are reflected on Ameren Missouri electric customer bills and on Ameren Missouri and Ameren Illinois natural gas customer bills. They are recorded gross in “Operating Revenues - Electric,” “Operating Revenues - Gas” and “Operating Expenses - Taxes other than income taxes” on the statement of income or the statement of income and comprehensive income. Excise taxes reflected on Ameren Illinois electric customer bills are imposed on the customer and are therefore not included in revenues and expenses. They are included in “Taxes accrued” on the balance sheet.
Uncertain Tax Positions 
Ameren’s federal income tax returns for the years 2007 through 2011 are before the Appeals Office of the IRS. Ameren’s federal income tax return for the year 2012 is currently under examination.
It is reasonably possible that a settlement will be reached with the Appeals Office of the IRS in the next 12 months for the years 2007 through 2011. This settlement, which is primarily related to uncertain tax positions for research tax deductions, is expected to result in a decrease in uncertain tax benefits of $20 million and $13 million for Ameren and Ameren Missouri, respectively. In addition, it is reasonably possible that other events will occur during the next 12 months that would cause the total amount of unrecognized tax benefits for the Ameren Companies to increase or decrease. However, the Ameren Companies do not believe any such increases or decreases, including the decrease from the reasonably possible IRS Appeals Office settlement discussed above, would be material to their results of operations, financial position, or liquidity.
State income tax returns are generally subject to examination for a period of three years after filing of the return. The Ameren Companies do not currently have material state income tax issues under examination, administrative appeals, or litigation. 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.
With the adoption of new accounting guidance in the first quarter of 2014, unrecognized tax benefits are recorded in “Accumulated deferred income taxes, net” as a reduction to the deferred tax assets for net operating loss and tax credit carryforwards on Ameren’s, Ameren Missouri’s and Ameren Illinois’ balance sheets. Unrecognized tax benefits that exceed these carryforwards are recorded in “Other deferred credits and liabilities” on the respective balance sheets. At March 31, 2014, unrecognized tax benefits of $84 million, $14 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 the respective balance sheets were reclassified to “Accumulated deferred income taxes, net” for comparative purposes.
Asset Retirement Obligations 
AROs at Ameren, Ameren Missouri and Ameren Illinois increased at March 31, 2014, compared to December 31, 2013, to reflect the accretion of obligations to their fair value, partially offset by immaterial settlements.
Noncontrolling Interest 
As of March 31, 2014, Ameren's noncontrolling interests were composed of the preferred stock not subject to mandatory redemption of Ameren Missouri and Ameren Illinois. All noncontrolling interests are classified as a component of equity separate from Ameren's equity on its consolidated balance sheet.
Accounting and Reporting Developments 
The following is a summary of recently adopted authoritative accounting guidance.
Presentation of an Unrecognized Tax Benefit
In July 2013, FASB issued additional authoritative accounting guidance to provide clarity for the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. 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 to the extent a net operating loss carryforward, a similar tax loss, or a tax credit carryforward is available under the tax law. This guidance was effective for the Ameren Companies beginning in the first quarter of 2014. Previously, unrecognized tax benefits were recorded in “Other deferred credits and liabilities” on Ameren's, Ameren Missouri's and Ameren Illinois' balance sheets. Beginning in the first quarter 2014, unrecognized tax benefits are recorded in “Accumulated deferred income taxes, net” as a reduction to the deferred tax assets for net operating loss and tax credit carryforwards on the respective balance sheets. Unrecognized tax benefits that exceed these carryforwards are recorded in “Other deferred credits and liabilities,” on the respective balance sheets. For comparative purposes, the Ameren Companies reclassified the December 31, 2013 balances in accordance with the new guidance as discussed in the Uncertain Tax Positions section above. 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.
Derivative Financial Instruments Derivative Financial Instruments (Policies)
Derivatives
We use derivatives principally to manage the risk of changes in market prices for natural gas, diesel, power, and uranium. Such price fluctuations may cause the following:
•
an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices;
•
market values of natural gas and uranium inventories that differ from the cost of those commodities in inventory; and
•
actual cash outlays for the purchase of these commodities that differ from anticipated cash outlays.
The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty.
Retirement Benefits Retirement Benefits (Policies)
Retirement Benefits
Ameren’s pension and postretirement plans are funded in compliance with income tax regulations and to meet federal funding or regulatory requirements. As a result, Ameren expects to fund its pension plans at a level equal to the greater of the pension expense or the legally required minimum contribution. Considering Ameren’s assumptions at March 31, 2014, the plan’s estimated investment performance through March 31, 2014, and Ameren’s pension funding policy, Ameren expects to make annual contributions of $20 million to $100 million in each of the next five years, with aggregate estimated contributions of $270 million. These amounts are estimates which may change with actual investment performance, changes in interest rates, any pertinent changes in government regulations, and any voluntary contributions. Our policy for postretirement benefits is primarily to fund the voluntary employees’ beneficiary association trusts to match the annual postretirement expense.
Summary Of Significant Accounting Policies (Tables)
Summary Of Nonvested Shares Related To Long-Term Incentive Plan 
A summary of nonvested performance share units at March 31, 2014, and changes during the three months ended March 31, 2014, under the 2006 Plan are presented below:
 
Performance Share Units
 
Share Units
Weighted-average Fair Value Per Unit at Grant Date
Nonvested at January 1, 2014
1,218,544

$
33.23

Granted(a)
680,606

38.90

Forfeitures
(46,758
)
33.29

Vested(b)
(116,297
)
38.81

Nonvested at March 31, 2014
1,736,095

$
35.08

(a)
Includes performance share units (share units) granted to certain executive and nonexecutive officers and other eligible employees in 2014 under the 2006 Plan.
(b)
Share units vested due to the 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.
Schedule Of Amortization Expense Based On Usage Of Renewable Energy Credits And Emission Allowances 
The following table presents amortization expense based on usage of renewable energy credits and emission allowances, net of gains from sales, for Ameren, Ameren Missouri and Ameren Illinois, during the three months ended March 31, 2014, and 2013:
 
Three Months
 
2014
 
2013
Ameren Missouri
$
6

(a) 
$
(b)

Ameren Illinois
 
3

 
 
4

Ameren
$
9

 
$
4

(a)
Includes higher priced renewable energy credits. 
(b)
Less than $1 million.
Schedule of Excise Taxes 
The following table presents excise taxes recorded in “Operating Revenues - Electric,” “Operating Revenues - Gas” and “Operating Expenses - Taxes other than income taxes” for the three months ended March 31, 2014, and 2013:
 
Three months
 
2014
 
2013
Ameren Missouri
$
34

 
$
33

Ameren Illinois
26

 
22

Ameren
$
60

 
$
55

Schedule of Unrecognized Tax Benefits 
The following table presents the amount of unrecognized tax benefits (detriments) as of March 31, 2014, and December 31, 2013:
 
March 31,
2014
 
December 31,
2013
 
 
Ameren
$
92

 
$
90

Ameren Missouri
32

 
31

Ameren Illinois
(1
)
 
(1
)
Schedule of Unrecognized Tax Benefits That Would Impact Effective Tax Rate 
The following table presents the amount of unrecognized tax benefits (detriments) as of March 31, 2014, and 2013, that would impact the effective tax rate, if recognized:
 
March 31,
2014
 
December 31,
2013
 
 
Ameren
$
55

 
$
54

Ameren Missouri
2

 
3

Ameren Illinois
(1
)
 
—

Equity Changes Attributable To Noncontrolling Interest 
A reconciliation of the equity changes attributable to the noncontrolling interests at Ameren for the three months ended March 31, 2014, and 2013, are shown below:
  
Three Months
 
  
2014
 
2013
 
Noncontrolling interests, beginning of period
$
142

 
$
151

(a) 
Net income from continuing operations attributable to noncontrolling interests
2

 
2

 
Dividends paid to noncontrolling interest holders
(2
)
 
(2
)
 
Noncontrolling interests, end of period
$
142

 
$
151

(a) 
(a)
Included the 20% EEI ownership interest not owned by Ameren prior to the divestiture of New AER to IPH. Prior to the divestiture of New AER, the assets and liabilities of EEI were consolidated in Ameren’s balance sheet at a 100% ownership level and were included in “Assets of discontinued operations” and “Liabilities of discontinued operations.” The divestiture of New AER, which included EEI, was completed in the fourth quarter of 2013. See Note 12 - Divestiture Transactions and Discontinued Operations for additional information.
Short-Term Debt And Liquidity Short-Term Debt and Liquidity (Tables)
Schedule of Short-term Debt [Table Text Block]
The following table summarizes the commercial paper activity and relevant interest rates under Ameren’s (parent) and Ameren Missouri’s commercial paper programs for the three months ended March 31, 2014, and 2013:
 
 
Ameren (parent)
Ameren Missouri
Ameren Consolidated
2014
 
 
 
 
 
Average daily commercial paper outstanding
 
$
339

 
$
200

$
539

Weighted-average interest rate
 
0.45
%
 
0.45
%
0.45
%
Peak commercial paper during period(a)
 
$
452

 
$
290

$
700

Peak interest rate
 
0.75
%
 
0.70
%
0.75
%
2013
 
 
 
 
 
Average daily commercial paper outstanding
 
$
2

 
$
—

$
2

Weighted-average interest rate
 
0.80
%
 
—
%
0.80
%
Peak commercial paper during period(a)
 
$
21

 
$
—

$
21

Peak interest rate
 
0.85
%
 
—
%
0.85
%

(a)
The timing of peak commercial paper issuances varies by company, and therefore the amounts presented by company might not equal the Ameren Consolidated peak commercial paper issuances for the period.
Long-Term Debt And Equity Financings (Tables)
Schedule Of Coverage Ratios 
Indenture Provisions and Other Covenants
Ameren Missouri’s and Ameren Illinois’ indentures and articles of incorporation include covenants and provisions related to issuances of first mortgage bonds and preferred stock. Ameren Missouri and Ameren Illinois are required to meet certain ratios to issue additional first mortgage bonds and preferred stock. A failure to achieve these ratios would not result in a default under these covenants and provisions, but would restrict the companies’ ability to issue bonds or preferred stock. The following table summarizes the required and actual interest coverage ratios for interest charges and dividend coverage ratios and bonds and preferred stock issuable as of March 31, 2014, at an assumed annual interest rate of 6% and dividend rate of 7%.
 
 
Required Interest
Coverage Ratio(a)
 
Actual Interest
Coverage Ratio
 
Bonds Issuable(b)
 
Required Dividend
Coverage Ratio(c)
 
Actual Dividend
Coverage Ratio
 
Preferred Stock
Issuable
 
Ameren Missouri
 
≥2.0
 
4.7
$
4,018

 
≥2.5
 
118.8
$
2,272

 
Ameren Illinois
 
≥2.0
 
7.6
 
3,732

(d) 
≥1.5
 
2.7
 
203

(e) 
(a)
Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.
(b)
Amount of bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include bonds issuable based on retired bond capacity of $729 million and $454 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 Instrument 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:
Environmental improvement and pollution control revenue bonds
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.
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 three months ended March 31, 2014, and 2013:
 
Three Months
 
 
2014
 
2013
 
Ameren:(a)
 
 
 
 
Miscellaneous income:
 
 
 
 
Allowance for equity funds used during construction
$
7

 
$
8

 
Interest income on industrial development revenue bonds
7

 
7

 
Interest and dividend income
2

 
—

 
Other
2

 
—

 
Total miscellaneous income
$
18

 
$
15

 
Miscellaneous expense:
 
 
 
 
Donations
$
5

 
$
4

 
Other
4

 
4

 
Total miscellaneous expense
$
9

 
$
8

 
Ameren Missouri:
 
 
 
 
Miscellaneous income:
 
 
 
 
Allowance for equity funds used during construction
$
7

 
$
7

 
Interest income on industrial development revenue bonds
7

 
7

 
Total miscellaneous income
$
14

 
$
14

 
Miscellaneous expense:
 
 
 
 
Donations
$
2

 
$
2

 
Other
2

 
3

 
Total miscellaneous expense
$
4

 
$
5

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

 
$
1

 
Interest and dividend income
2

 
—

 
Other
1

 
—

 
Total miscellaneous income
$
3

 
$
1

 
Miscellaneous expense:
 
 
 
 
Donations
$
3

 
$
3

 
Other
1

 
—

 
Total miscellaneous expense
$
4

 
$
3

 
(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

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 March 31, 2014, and December 31, 2013. As of March 31, 2014, these contracts ran through October 2016, October 2019, May 2032, and October 2016 for fuel oils, natural gas, power, and uranium, respectively.
  
Quantity (in millions, except as indicated)
 
2014
2013
Commodity
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Fuel oils (in gallons)(a)
53

(b)

53

66

(b)

66

Natural gas (in mmbtu)
28

109

137

28

108

136

Power (in megawatthours)
2

11

13

3

11

14

Uranium (pounds in thousands)
827

(b)

827

796

(b)

796

(a)
Fuel oils consist of ultra-low-sulfur diesel, on-highway diesel, and crude oil.
(b)
Not applicable.
Derivative Instruments Carrying Value 
The following table presents the carrying value and balance sheet location of all derivative instruments as of March 31, 2014, and December 31, 2013:
 
Balance Sheet Location
 
Ameren Missouri
 
Ameren Illinois
 
Ameren
2014
 
 
 
 
 
 
Derivative assets not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current assets
 
$
5

 
$
—

 
$
5

 
Other assets
 
1

 
—

 
1

Natural gas
Other current assets
 
1

 
5

 
6

 
Other assets
 
1

 
—

 
1

Power
Other current assets
 
15

 
—

 
15

 
Total assets
 
$
23

 
$
5

 
$
28

Derivative liabilities not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current liabilities
 
$
2

 
$
—

 
$
2

 
Other deferred credits and liabilities
 
2

 
—

 
2

Natural gas
Other current liabilities
 
4

 
16

 
20

 
Other deferred credits and liabilities
 
4

 
13

 
17

Power
Other current liabilities
 
6

 
8

 
14

 
Other deferred credits and liabilities
 
—

 
112

 
112

Uranium
Other current liabilities
 
4

 
—

 
4

 
Other deferred credits and liabilities
 
1

 
—

 
1

 
Total liabilities
 
$
23

 
$
149

 
$
172

2013
 
 
 
 
 
 
Derivative assets not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current assets
 
$
6

 
$
—

 
$
6

 
Other assets
 
3

 
—

 
3

Natural gas
Other current assets
 
1

 
1

 
2

Power
Other current assets
 
23

 
—

 
23

 
Total assets
 
$
33

 
$
1

 
$
34

Derivative liabilities not designated as hedging instruments(a)
 
 
 
 
 
 
Commodity contracts:
 
 
 
 
 
 
 
Fuel oils
Other current liabilities
 
$
2

 
$
—

 
$
2

 
Other deferred credits and liabilities
 
1

 
—

 
1

Natural gas
Other current liabilities
 
5

 
27

 
32

 
Other deferred credits and liabilities
 
6

 
19

 
25

Power
Other current liabilities
 
4

 
9

 
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)
Includes derivatives subject to regulatory deferral.

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 as regulatory assets or regulatory liabilities as of March 31, 2014, and December 31, 2013:
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2014
 
 
 
 
 
Cumulative gains (losses) deferred as regulatory liabilities or assets:
 
 
 
 
 
Fuel oils derivative contracts(a)
$
—

 
$
—

 
$
—

Natural gas derivative contracts(b)
(6
)
 
(24
)
 
(30
)
Power derivative contracts(c)
9

 
(120
)
 
(111
)
Uranium derivative contracts(d)
(5
)
 
—

 
(5
)
2013
 
 
 
 
 
Cumulative gains (losses) deferred as regulatory liabilities or assets:
 
 
 
 
 
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 gains (losses) on fuel oils derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s transportation costs for coal through December 2016 as of March 31, 2014. Current gains deferred as regulatory liabilities include $2 million and $2 million at Ameren and Ameren Missouri, respectively, as of March 31, 2014. Current losses deferred as regulatory assets include $1 million and $1 million at Ameren and Ameren Missouri, respectively, as of March 31, 2014.
(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 2017 at Ameren Illinois, in each case as of March 31, 2014. Current gains deferred as regulatory liabilities include $6 million, $1 million, and $5 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of March 31, 2014. Current losses deferred as regulatory assets include $20 million, $4 million, and $16 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of March 31, 2014.
(c)
Represents net gains (losses) associated with power derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri, in each case as of March 31, 2014. Current gains deferred as regulatory liabilities include $15 million and $15 million at Ameren and Ameren Missouri, respectively, as of March 31, 2014. Current losses deferred as regulatory assets include $14 million, $6 million, and $8 million at Ameren, Ameren Missouri and Ameren Illinois, respectively, as of March 31, 2014.
(d)
Represents net losses on uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s uranium requirements through December 2016, as of March 31, 2014. Current losses deferred as regulatory assets include $4 million and $4 million at Ameren and Ameren Missouri, respectively, as of March 31, 2014.
Offsetting Derivative Assets and Liabilities 
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 March 31, 2014, and December 31, 2013:
 
 
 
 
Gross Amounts Not Offset in the Balance Sheet
 
 
Commodity Contracts Eligible to be Offset
 
Gross Amounts Recognized in the Balance Sheet
 
Derivative Instruments
 
Cash Collateral Received/Posted(a)
 
Net
Amount
2014
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
23

 
$
9

 
$
—

 
$
14

Ameren Illinois
 
5

 
3

 
—

 
2

Ameren
 
$
28

 
$
12

 
$
—

 
$
16

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
23

 
$
9

 
$
9

 
$
5

Ameren Illinois
 
149

 
3

 
3

 
143

Ameren
 
$
172

 
$
12

 
$
12

 
$
148

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.
Derivative Instruments With Credit Risk-Related Contingent Features 
The additional collateral required is the net liability position allowed under the master trading and netting agreements, assuming (1) the credit risk-related contingent features underlying these agreements were triggered on March 31, 2014, or December 31, 2013, respectively, and (2) those counterparties with rights to do so requested collateral.
 
Aggregate Fair Value of
Derivative Liabilities(a)
 
Cash
Collateral Posted
 
Potential Aggregate Amount of
Additional  Collateral Required(b)
2014
 
 
 
 
 
Ameren Missouri
$
56

 
$
2

 
$
51

Ameren Illinois
80

 
3

 
65

Ameren
$
136

 
$
5

 
$
116

2013
 
 
 
 
 
Ameren Missouri
$
70

 
$
2

 
$
67

Ameren Illinois
75

 
15

 
55

Ameren
$
145

 
$
17

 
$
122

(a)
Prior to consideration of master trading and netting agreements and including NPNS and accrual contract exposures.
(b)
As collateral requirements with certain counterparties are based on master trading and netting agreements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such agreements.
Fair Value Measurements (Tables)
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Valuation Techniques 
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 March 31, 2014:
 
 
Fair Value
 
 
 
Weighted Average
 
 
Assets
Liabilities
Valuation Technique(s)
Unobservable Input
Range
Level 3 Derivative asset and liability - commodity contracts(a):
 
 
 
Ameren
Fuel oils
$
5

$
(4
)
Option model
Volatilities(%)(b)
13 - 34
16
 
 
 
 
Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.25 - 0.99
0.63
 
Natural gas
1

(1
)
Option model
Volatilities(%)(b)
27 - 102
40
 
 
 
 
 
Nodal basis($/mmbtu)(c)
(0.3) - (0.2)
(0.2)
 
 
 
 
Discounted cash flow
Nodal basis($/mmbtu)(c)
(0.2) - (0.1)
(0.1)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.27 - 5
1
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
0.43
(e)
 
Power(f)
14

(124
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)
27 - 57
33
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(1,109) - 2,981
474
 
 
 
 
 
Nodal basis($/MWh)(c)
(6) - (1)
(3)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.35
(e)
 
 
 
 
 
Ameren Missouri and Ameren Illinois credit risk(%)(c)(d)
0.43
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 6
5
 
 
 
 
 
Escalation rate(%)(b)(g)
2 - 3
3
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 7
6
 
Uranium
—

(5
)
Discounted cash flow
Average forward uranium pricing($/pound)(b)
34 - 40
35
Ameren Missouri
Fuel oils
$
5

$
(4
)
Option model
Volatilities(%)(b)
13 - 34
16
 
 
 
 
Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.25 - 0.99
0.63
 
Natural gas
1

(1
)
Option model
Volatilities(%)(b)
27 - 102
40
 
 
 
 
 
Nodal basis($/mmbtu)(c)
(0.3) - (0.2)
(0.2)
 
 
 
 
Discounted cash flow
Nodal basis($/mmbtu)(c)
(0.2) - (0.1)
(0.1)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.27 - 5
1
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
0.43
(e)
 
Power(f)
14

(4
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(c)
30 - 57
45
 
 
 
 
 
Estimated auction price for FTRs($/MW)(b)
(1,109) - 2,981
474
 
 
 
 
 
Nodal basis($/MWh)(c)
(3) - (1)
(2)
 
 
 
 
 
Counterparty credit risk(%)(c)(d)
0.35
(e)
 
 
 
 
 
Ameren Missouri credit risk(%)(c)(d)
0.43
(e)
 
Uranium
—

(5
)
Discounted cash flow
Average forward uranium pricing($/pound)(b)
34 - 40
35
Ameren Illinois
Power(f)
$
—

$
(120
)
Discounted cash flow
Average forward peak and off-peak pricing - forwards/swaps($/MWh)(b)
27 - 40
32
 
 
 
 
 
Nodal basis($/MWh)(b)
(6) - (1)
(3)
 
 
 
 
 
Ameren Illinois credit risk(%)(c)(d)
0.43
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 6
5
 
 
 
 
 
Escalation rate(%)(b)(g)
2 - 3
3
 
 
 
 
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)
Not applicable.
(f)
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.
(g)
Escalation rate applies to power prices 2026 and beyond.
The following table describes the valuation techniques and unobservable inputs for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2013:
 
 
Fair Value
 
 
 
Weighted Average
 
 
Assets
Liabilities
Valuation Technique(s)
Unobservable Input
Range
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)
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 March 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
 
$
1

 
$
—

 
$
5

 
$
6

 
 
Natural gas
 
—

 
6

 
1

 
7

 
 
Power
 
—

 
1

 
14

 
15

 
 
Total derivative assets - commodity contracts
 
$
1

 
$
7

 
$
20

 
$
28

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
2

 
$
—

 
$
—

 
$
2

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
327

 
—

 
—

 
327

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
61

 
—

 
61

 
 
Municipal bonds
 
—

 
2

 
—

 
2

 
 
U.S. treasury and agency securities
 
—

 
94

 
—

 
94

 
 
Asset-backed securities
 
—

 
14

 
—

 
14

 
 
Other
 
—

 
1

 
—

 
1

 
 
Total nuclear decommissioning trust fund
 
$
329

 
$
172

 
$
—

 
$
501

(b) 
 
Total Ameren
 
$
330

 
$
179

 
$
20

 
$
529

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

 
$
—

 
$
5

 
$
6

 
 
Natural gas
 
—

 
1

 
1

 
2

 
 
Power
 
—

 
1

 
14

 
15

 
 
Total derivative assets - commodity contracts
 
$
1

 
$
2

 
$
20

 
$
23

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
2

 
$
—

 
$
—

 
$
2

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
327

 
—

 
—

 
327

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
Corporate bonds
 
—

 
61

 
—

 
61

 
 
Municipal bonds
 
—

 
2

 
—

 
2

 
 
U.S. treasury and agency securities
 
—

 
94

 
—

 
94

 
 
Asset-backed securities
 
—

 
14

 
—

 
14

 
 
Other
 
—

 
1

 
—

 
1

 
 
Total nuclear decommissioning trust fund
 
$
329

 
$
172

 
$
—

 
$
501

(b) 
 
Total Ameren Missouri
 
$
330

 
$
174

 
$
20

 
$
524

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

 
$
5

 
$
—

 
$
5

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

 
$
—

 
$
4

 
$
4

 
 
Natural gas
 
2

 
34

 
1

 
37

 
 
Power
 
—

 
2

 
124

 
126

 
 
Uranium
 
—

 
—

 
5

 
5

 
 
Total Ameren
 
$
2

 
$
36

 
$
134

 
$
172

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

 
$
—

 
$
4

 
$
4

 
 
Natural gas
 
2

 
5

 
1

 
8

 
 
Power
 
—

 
2

 
4

 
6

 
 
Uranium
 
—

 
—

 
5

 
5

 
 
Total Ameren Missouri
 
$
2

 
$
7

 
$
14

 
$
23

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

 
$
29

 
$
—

 
$
29

 
 
Power
 
—

 
—

 
120

 
120

 
 
Total Ameren Illinois
 
$
—

 
$
29

 
$
120

 
$
149

 
(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

 
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
Derivative assets - commodity contracts(a):
 
 
 
 
 
 
 
 
Missouri
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
Derivative assets - commodity contracts(a):
 
 
 
 
 
 
 
 
Illinois
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
Derivative liabilities - commodity contracts(a):
 
 
 
 
 
 
 
 
Missouri
Fuel oils
 
$
—

 
$
—

 
$
3

 
$
3

 
Natural gas
 
3

 
8

 
—

 
11

 
Power
 
—

 
2

 
2

 
4

 
Uranium
 
—

 
—

 
6

 
6

 
Total Ameren Missouri
 
$
3

 
$
10

 
$
11

 
$
24

Ameren
Derivative liabilities - commodity contracts(a):
 
 
 
 
 
 
 
 
Illinois
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 Three 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 three months ended March 31, 2014:
  
 
Net derivative commodity contracts
Three Months
 
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
 
(2
)
 
(a)

 
(2
)
Settlements
 
(2
)
 
(a)

 
(2
)
Ending balance at March 31, 2014
$
1

$
(a)

$
1

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

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

$
—

$
—

Purchases
 
—

 
(2
)
 
(2
)
Settlements
 
—

 
2

 
2

Ending balance at March 31, 2014
$
—

$
—

$
—

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

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
19

$
(108
)
$
(89
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(5
)
 
(12
)
 
(17
)
Settlements
 
(5
)
 
—

 
(5
)
Transfers out of Level 3
 
1

 
—

 
1

Ending balance at March 31, 2014
$
10

$
(120
)
$
(110
)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2014
$
(1
)
$
(14
)
$
(15
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2014
$
(6
)
$
(a)

$
(6
)
Settlements
 
1

 
(a)

 
1

Ending balance at March 31, 2014
$
(5
)
$
(a)

$
(5
)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2014
$
—

$
(a)

$
—

(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 three months ended March 31, 2013:
  
 
Net derivative commodity contracts
Three Months
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
5

$
(a)

$
5

Purchases
 
1

 
(a)

 
1

Settlements
 
(1
)
 
(a)

 
(1
)
Ending balance at March 31, 2013
$
5

$
(a)

$
5

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

$
2

$
2

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

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
11

$
(111
)
$
(100
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
5

 
14

 
19

Settlements
 
(13
)
 
16

 
3

Transfers into Level 3
 
(2
)
 
—

 
(2
)
Transfers out of Level 3
 
1

 
—

 
1

Ending balance at March 31, 2013
$
2

$
(81
)
$
(79
)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2013
$
(3
)
$
14

$
11

Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2013
$
(2
)
$
(a)

$
(2
)
Ending balance at March 31, 2013
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at March 31, 2013
$
—

$
(a)

$
—

(a)
Not applicable.
Schedule Of Transfers Between Fair Value Hierarchy Levels 
The following table summarizes all transfers between fair value hierarchy levels related to derivative commodity contracts for the three months ended March 31, 2014, and 2013:
  
Three Months
 
2014
2013
Derivative commodity contracts
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Transfers into Level 3 / Transfers out of Level 2 - Power
$
—

$
—

$
—

$
(2
)
$
—

$
(2
)
Transfers out of Level 3 / Transfers into Level 2 - Power
1

—

1

1

—

1

Net fair value of Level 3 transfers
$
1

$
—

$
1

$
(1
)
$
—

$
(1
)
Schedule Of Carrying Amounts And Estimated Fair Values Of Long-Term Debt, Capital Lease Obligations And Preferred Stock 
The following table presents the carrying amounts and estimated fair values of our long-term debt, capital lease obligations and preferred stock at March 31, 2014, and December 31, 2013:
  
March 31, 2014
 
December 31, 2013
  
Carrying
Amount
 
Fair
Value
 
Carrying
Amount
 
Fair
Value
Ameren:(a)
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
5,874

 
$
6,530

 
$
6,038

 
$
6,584

Preferred stock
142

 
119

 
142

 
118

Ameren Missouri:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
3,758

 
$
4,200

 
$
3,757

 
$
4,124

Preferred stock
80

 
71

 
80

 
71

Ameren Illinois:
 
 
 
 
 
 
 
Long-term debt (including current portion)
$
1,692

 
$
1,903

 
$
1,856

 
$
2,028

Preferred stock
62

 
48

 
62

 
47

(a)
Preferred stock is recorded in “Noncontrolling Interests” on the consolidated balance sheet.
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 three months ended March 31, 2014, and 2013. It is based primarily on the agreements discussed above and in Note 14 - Related Party Transactions under Part II, Item 8, of the Form 10-K, and the money pool arrangements discussed in Note 3 - Short-term Debt and Liquidity of this report.
  
  
 
  
 
Three Months
Agreement
Income Statement
Line Item
 
  
 
Ameren
Missouri
 
Ameren
Illinois
Ameren Missouri power supply
Operating Revenues
 
2014
$
(b)
$
(a)

agreements with Ameren Illinois
 
 
2013
 
1
 
(a)

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2014
 
5
 
(b)

rent and facility services
 
 
2013
 
5
 
(b)

Total Operating Revenues
 
 
2014
$
5
$
(b)

 
 
 
2013
 
6
 
(b)

Ameren Illinois power supply
Purchased Power
 
2014
$
(a)
$
(b)

agreements with Ameren Missouri
 
 
2013
 
(a)
 
1

Ameren Illinois transmission
Purchased Power
 
2014
 
(a)
 
1

services with ATXI
 
 
2013
 
(a)
 
1

Total Purchased Power
 
 
2014
$
(a)
$
1

 
 
 
2013
 
(a)
 
2

Ameren Services support services
Other Operations and Maintenance
 
2014
$
33
$
27

agreement
 
 
2013
 
31
 
25

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

 
 
 
2013
 
(b)
 
(a)

Total Other Operations and
 
 
2014
$
33
$
27

Maintenance Expenses
 
 
2013
 
31
 
25

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

 
 
 
2013
 
(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, property damage, and terrorism coverage.
Commitments And Contingencies (Tables)
Schedule of Insurance Coverage at Callaway Energy Center 
The following table presents insurance coverage at Ameren Missouri’s Callaway energy center at March 31, 2014. The property coverage and the nuclear liability coverage must be renewed on April 1 and January 1, respectively, of each year. Both coverages were renewed in 2014.
Type and Source of Coverage
Maximum  Coverages
 
Maximum Assessments
for Single Incidents
 
Public liability and nuclear worker liability:
 
 
 
 
American Nuclear Insurers
$
375

  
$
—

  
Pool participation
13,241

(a) 
128

(b) 
 
$
13,616

(c) 
$
128

  
Property damage:
 
 
 
 
NEIL
$
2,250

(d) 
$
23

(e) 
European Mutual Association for Nuclear Insurance
500

(f) 
—

 
 
$
2,750

 
$
23

 
Replacement power:
 
 
 
 
NEIL
$
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 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. There is a $1.7 billion sublimit for nonradiation events, of which the last $200 million is a shared limit with other generators purchasing this coverage. The $1.7 billion sublimit for nonradiation events was not included with the April 1, 2014 renewal.
(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 at our nuclear energy center. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first eight weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter for a total not exceeding the policy limit of $490 million. Nonradiation events are sub-limited to $327.6 million.
(h)
Provides replacement power cost insurance in the event of a prolonged accidental outage at our nuclear energy center. The coverage commences after the first 52 weeks of insurance coverage from NEIL and is a weekly indemnity of $900,000 for 71 weeks in excess of the $3.6 million per week set forth above. Missouri Energy Risk Assurance Company LLC is an affiliate and has reinsured this coverage with third-party insurance companies. See Note 8 - Related Party Transactions for more information on this affiliate transaction.
Schedule of Estimated Obligations for Manufactured Gas Plant Remediation 
The following table presents, as of March 31, 2014, the estimated obligation to complete the remediation of these former MGP sites:
  
Estimate
 
Recorded
  Liability(a)
  
Low
 
High
 
Ameren
$
269

 
$
345

 
$
269

Ameren Missouri
3

 
4

 
3

Ameren Illinois
266

 
341

 
266

(a)
Recorded liability represents the estimated minimum probable obligations, as no other amount within the range was a better estimate.
Schedule of Asbestors-Related Litigation Pending Lawsuits 
The following table presents the pending asbestos-related lawsuits filed against the Ameren Companies as of March 31, 2014:
Ameren
 
Ameren
Missouri
 
Ameren
Illinois
 
Total(a)
1
 
47
 
56
 
71
(a)
Total does not equal the sum of the subsidiary unit lawsuits because some of the lawsuits name multiple Ameren entities as defendants.
Retirement Benefits (Tables)
Components Of Net Periodic Benefit Cost 
The following table presents the components of the net periodic benefit cost for Ameren’s pension and postretirement benefit plans for the three months ended March 31, 2014, and 2013:
  
Pension Benefits
 
Postretirement Benefits
 
Three Months
 
Three Months
  
2014
 
2013
 
2014
 
2013
Service cost
$
21

 
$
24

 
$
5

 
$
6

Interest cost
49

 
40

 
13

 
12

Expected return on plan assets
(57
)
 
(54
)
 
(16
)
 
(16
)
Amortization of:
 
 
 
 
 
 
 
Prior service cost (benefit)
—

 
(1
)
 
(1
)
 
(1
)
Actuarial loss
12

 
22

 
(1
)
 
2

Net periodic benefit cost
$
25

 
$
31

 
$
—

 
$
3


Summary Of Benefit Plan Costs Incurred 
Ameren Missouri and Ameren Illinois are responsible for their respective shares of Ameren’s pension and postretirement costs. The following table presents the pension costs and the postretirement benefit costs incurred for the three months ended March 31, 2014, and 2013:
  
Pension Costs
Postretirement Costs
 
Three Months
 
Three Months
  
2014
 
2013
 
2014
 
2013
Ameren Missouri
$
17

 
$
18

 
$
1

 
$
2

Ameren Illinois
8

 
10

 
(1
)
 
1

Other
—

 
3

 
—

 
—

Ameren(a)
$
25

 
$
31

 
$
—

 
$
3

(a)
Includes amounts for Ameren registrants and nonregistrant subsidiaries.
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 carrying amounts of the components of assets and liabilities segregated on Ameren's consolidated balance sheets as discontinued operations at March 31, 2014, and December 31, 2013:
 
March 31, 2014
 
December 31, 2013
Assets of discontinued operations
 
 
 
Cash and cash equivalents
$
—

 
$
—

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
$
2

 
$
5

Asset retirement obligations(b)
31

 
40

Total liabilities of discontinued operations
$
33

 
$
45


(a)
Balances primarily consist of deferred income tax assets related to the abandoned Meredosia and Hutsonville energy centers.
(b)
Includes AROs associated with the abandoned Meredosia and Hutsonville energy centers of $31 million at March 31, 2014, and December 31, 2013.
for the three months ended March 31, 2014, and 2013:
 
Three months
 
 
2014
 
2013
 
Operating revenues
$
1

 
$
264

 
Operating expenses
(2
)
 
(415
)
(a) 
Operating loss
(1
)
 
(151
)
 
Other loss
—

 
(2
)
 
Interest charges
—

 
(11
)
 
Loss before income taxes
(1
)
 
(164
)
 
Income tax expense
—

 
(35
)
 
Loss from discontinued operations, net of taxes
$
(1
)
 
$
(199
)
 

(a)
Included a noncash pretax asset impairment charge of $155 million
Schedule Of Coverage Ratios 
Indenture Provisions and Other Covenants
Ameren Missouri’s and Ameren Illinois’ indentures and articles of incorporation include covenants and provisions related to issuances of first mortgage bonds and preferred stock. Ameren Missouri and Ameren Illinois are required to meet certain ratios to issue additional first mortgage bonds and preferred stock. A failure to achieve these ratios would not result in a default under these covenants and provisions, but would restrict the companies’ ability to issue bonds or preferred stock. The following table summarizes the required and actual interest coverage ratios for interest charges and dividend coverage ratios and bonds and preferred stock issuable as of March 31, 2014, at an assumed annual interest rate of 6% and dividend rate of 7%.
 
 
Required Interest
Coverage Ratio(a)
 
Actual Interest
Coverage Ratio
 
Bonds Issuable(b)
 
Required Dividend
Coverage Ratio(c)
 
Actual Dividend
Coverage Ratio
 
Preferred Stock
Issuable
 
Ameren Missouri
 
≥2.0
 
4.7
$
4,018

 
≥2.5
 
118.8
$
2,272

 
Ameren Illinois
 
≥2.0
 
7.6
 
3,732

(d) 
≥1.5
 
2.7
 
203

(e) 
(a)
Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.
(b)
Amount of bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include bonds issuable based on retired bond capacity of $729 million and $454 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.
Segment Information (Tables)
Schedule Of Segment Reporting Information By Segment
The following table presents information about the reported revenues and specified items reflected in Ameren’s net income attributable to Ameren Corporation from continuing operations for the three months ended March 31, 2014, and 2013, and total assets in continuing operations as of March 31, 2014, and December 31, 2013.
Three Months
Ameren
Missouri
 
Ameren
Illinois
 
Other
 
Intersegment
Eliminations
 
Ameren
 
2014
 
 
 
 
 
 
 
 
 
 
External revenues
$
811

 
$
774

 
$
9

 
$
—

 
$
1,594

 
Intersegment revenues
6

 
—

 
1

 
(7
)
 
—

 
Net income (loss) attributable to Ameren Corporation from continuing operations
47

 
53

 
(3
)
 
—

 
97

 
2013
 
 
 
 
 
 
 
 
 
 
External revenues
$
789

 
$
684

 
$
2

 
$
—

 
$
1,475

 
Intersegment revenues
7

 
—

 
2

 
(9
)
 
—

 
Net income (loss) attributable to Ameren Corporation from continuing operations
40

 
31

 
(17
)
 
—

 
54

 
As of March 31, 2014:
 
 
 
 
 
 
 
 
 
 
Total assets
$
12,948

 
$
7,640

 
$
898

 
$
(335
)
 
$
21,151

(a) 
As of December 31, 2013:
 
 
 
 
 
 
 
 
 
 
Total assets
$
12,904

 
$
7,454

 
$
752

 
$
(233
)
 
$
20,877

(a) 
(a)    Excludes total assets from discontinued operations of $15 million and $165 million as of March 31, 2014, and December 31, 2013, respectively.
Summary Of Significant Accounting Policies (Narrative) (Detail) (USD $)
In Millions, except Per Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Maximum shares available for grants
8 
 
Closing common share price
 
$ 36.16 
Book value of renewable energy credits
$ 17 
$ 22 
Unrecognized tax benefit recorded in Accumulated deferred income taxes, net
84 
84 
Estimated unrecognized tax decreases resulting from settlements with taxing authorities
20 
 
Union Electric Company
 
 
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Book value of renewable energy credits
17 
22 
Unrecognized tax benefit recorded in Accumulated deferred income taxes, net
14 
15 
Estimated unrecognized tax decreases resulting from settlements with taxing authorities
13 
 
Ameren Illinois Company
 
 
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Unrecognized tax benefit recorded in Accumulated deferred income taxes, net
$ 0 
$ 0 
Electric Energy, Inc
 
 
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Percentage of EEI not owned by Ameren
 
20.00% 
Performance Shares
 
 
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Fair value of each share unit, per share
$ 38.90 1
 
Performance period
3 years 
 
Risk free interest rate period
3 years 
 
Three-year risk-free rate
0.78% 
 
Volatility rate, minimum
12.00% 
 
Volatility rate, maximum
18.00% 
 
Power |
Union Electric Company
 
 
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Number of customers
 
1,200,000 
Power |
Ameren Illinois Company
 
 
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Number of customers
 
1,200,000 
Natural Gas |
Union Electric Company
 
 
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Number of customers
 
127,000 
Natural Gas |
Ameren Illinois Company
 
 
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Number of customers
 
807,000 
Summary Of Significant Accounting Policies (Schedule Of Amortization Expense Based On Usage Of Renewable Energy Credits And Emission Allowances) (Detail) (REC and Emission Allowances, USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Finite-Lived Intangible Assets [Line Items]
 
 
Amortization of intangible assets
$ 9 
$ 4 
Union Electric Company
 
 
Finite-Lived Intangible Assets [Line Items]
 
 
Amortization of intangible assets
6 1
1 2
Ameren Illinois Company
 
 
Finite-Lived Intangible Assets [Line Items]
 
 
Amortization of intangible assets
$ 3 
$ 4 
Summary Of Significant Accounting Policies (Schedule Of Excise Taxes) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Accounting Policies [Line Items]
 
 
Excise tax expense
$ 60 
$ 55 
Union Electric Company
 
 
Accounting Policies [Line Items]
 
 
Excise tax expense
34 
33 
Ameren Illinois Company
 
 
Accounting Policies [Line Items]
 
 
Excise tax expense
$ 26 
$ 22 
Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Schedule of Unrecognized Tax Benefits (Detriments)) (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Schedule of Unrecognized Tax Benefits (Detriments) [Line Items]
 
 
Unrecognized tax benefits (detriments)
$ 92 
$ 90 
Union Electric Company
 
 
Schedule of Unrecognized Tax Benefits (Detriments) [Line Items]
 
 
Unrecognized tax benefits (detriments)
32 
31 
Ameren Illinois Company
 
 
Schedule of Unrecognized Tax Benefits (Detriments) [Line Items]
 
 
Unrecognized tax benefits (detriments)
$ (1)
$ (1)
Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Schedule of Unrecognized Tax Benefits (Detriments) That Would Impact the Effective Tax Rate) (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Schedule of Unrecognized Tax Benefits (Detriments) That Would Impact Effective Tax Rate [Line Items]
 
 
Unrecognized tax benefits (detriments) that would impact effective tax rate
$ 55 
$ 54 
Union Electric Company
 
 
Schedule of Unrecognized Tax Benefits (Detriments) That Would Impact Effective Tax Rate [Line Items]
 
 
Unrecognized tax benefits (detriments) that would impact effective tax rate
2 
3 
Ameren Illinois Company
 
 
Schedule of Unrecognized Tax Benefits (Detriments) That Would Impact Effective Tax Rate [Line Items]
 
 
Unrecognized tax benefits (detriments) that would impact effective tax rate
$ (1)
$ 0 
Summary Of Significant Accounting Policies (Equity Changes Attributable To Noncontrolling Interest) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Dec. 31, 2013
Electric Energy, Inc
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
 
 
 
Noncontrolling interest, beginning of period
$ 142 
$ 151 1
 
Net income from continuing operations attributable to noncontrolling interests
2 
2 
 
Dividends paid to noncontrolling interest holders
(2)
(2)
 
Noncontrolling interest, end of period
$ 142 
$ 151 1
 
Percentage of EEI not owned by Ameren
 
 
20.00% 
Rate And Regulatory Matters (Narrative-Missouri) (Detail) (USD $)
In Millions, unless otherwise specified
1 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Mar. 31, 2014
Union Electric Company
Dec. 31, 2013
Union Electric Company
Mar. 31, 2014
Electric Distribution [Member]
Union Electric Company
Accounting Authority Order Request [Member]
Feb. 28, 2014
Customer [Domain]
Electric Distribution [Member]
Union Electric Company
Feb. 13, 2014
Customer [Domain]
Electric Distribution [Member]
Union Electric Company
customer
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
Regulatory assets
$ 1,251 
$ 1,240 
$ 539 
$ 534 
$ 36 
 
 
Number of Customers Filed Complaint Case
 
 
 
 
 
 
37 
Contested return on equity
 
 
 
 
 
9.80% 
 
Customer Requested Rate Decrease
 
 
 
 
 
$ 67 
 
Customer Requested Rate on Equity
 
 
 
 
 
9.40% 
 
Rate And Regulatory Matters (Narrative-Illinois) (Detail) (USD $)
12 Months Ended 3 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Mar. 31, 2014
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Gas Distribution [Member]
Final Rate Order [Member]
Dec. 31, 2013
Ameren Illinois Company
Gas Distribution [Member]
Rate order appeal [Member]
Mar. 31, 2014
Ieima [Member]
Ameren Illinois Company
Electric Distribution [Member]
IEMA Revenue Requirement Reconciliation [Member]
Mar. 31, 2014
Pending Ferc Case [Member]
Midwest Independent Transmission System Operator, Inc [Member]
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
 
Regulatory assets
$ 1,251,000,000 
$ 1,240,000,000 
$ 706,000,000 
$ 701,000,000 
 
 
$ 24,000,000 
 
Requested rate decrease, amount
 
 
 
 
 
 
206,000,000 
 
Authorized Increase in Revenue from Utility Service
 
 
 
 
32,000,000 
 
 
 
Rate Of Return On Common Equity
 
 
 
 
9.10% 
10.40% 
 
12.38% 
Percent Of Capital Structure Composed Of Equity
 
 
 
 
51.70% 
 
 
 
Rate Base
 
 
 
 
$ 1,100,000,000 
 
 
 
Rate And Regulatory Matters (Narrative-Federal) (Detail) (USD $)
In Millions, unless otherwise specified
1 Months Ended 12 Months Ended 3 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Mar. 31, 2014
Ameren Illinois Company
Dec. 31, 2013
Ameren Illinois Company
Mar. 31, 2014
Ameren Illinois Company
Pending Ferc Case [Member]
Maximum
Mar. 31, 2014
Union Electric Company
Dec. 31, 2013
Union Electric Company
Dec. 31, 2013
Union Electric Company
New Nuclear Energy Center COL [Member]
Dec. 31, 2013
Union Electric Company
New Nuclear Energy Center COL [Member]
Minimum
Dec. 31, 2013
Union Electric Company
New Nuclear Energy Center COL [Member]
Maximum
Mar. 31, 2014
Wholesale Distribution Rate Case [Member]
Dec. 31, 2013
Wholesale Distribution Rate Case [Member]
Jan. 31, 2011
Wholesale Distribution Rate Case [Member]
Ameren Illinois Company
appraiser
Mar. 31, 2014
Wholesale Distribution Rate Case [Member]
Ameren Illinois Company
Dec. 31, 2013
Wholesale Distribution Rate Case [Member]
Ameren Illinois Company
Dec. 31, 2012
Entergy Refund [Member]
Union Electric Company
Mar. 31, 2014
Entergy Refund [Member]
Union Electric Company
Mar. 31, 2014
Midwest Independent Transmission System Operator, Inc [Member]
Pending Ferc Case [Member]
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Number of Customers, Reached Agreements
 
 
 
 
 
 
 
 
 
 
 
 
4 
 
 
 
 
 
Number of Wholesale Customers
 
 
 
 
 
 
 
 
 
 
 
 
9 
 
 
 
 
 
Number of Customers, Remaining on Agreements
 
 
 
 
 
 
 
 
 
 
 
 
5 
 
 
 
 
 
Current regulatory liabilities
$ 248 
$ 216 
$ 201 
$ 159 
 
$ 47 
$ 57 
 
 
 
$ 14 
$ 13 
 
$ 14 
$ 13 
 
 
 
Customer Requested Rate on Equity
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
9.15% 
Rate Of Return On Common Equity
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
12.38% 
Proceeds from Legal Settlements
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
31 
 
 
Range of possible loss, minimum
 
 
 
 
19 
 
 
 
 
 
 
 
 
 
 
 
25 
 
Investments in Power and Distribution Projects
 
 
 
 
 
 
 
$ 69 
$ 80 
$ 100 
 
 
 
 
 
 
 
 
Short-Term Debt And Liquidity (Narrative) (Detail) (USD $)
3 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Mar. 31, 2014
Ameren (parent) [Domain]
Dec. 31, 2013
Ameren (parent) [Domain]
Mar. 31, 2014
Union Electric Company
Dec. 31, 2013
Union Electric Company
Mar. 31, 2014
Utilities [Member]
Mar. 31, 2013
Utilities [Member]
Mar. 31, 2014
Credit Agreements 2012 [Member]
Mar. 31, 2014
Credit Agreements 2012 [Member]
Maximum
Mar. 31, 2014
Missouri Credit Agreement 2012 [Member]
Union Electric Company
Mar. 31, 2014
Illinois Credit Agreement 2012 [Member]
Ameren Illinois Company
Line of Credit Facility [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
Line of credit facility, maximum borrowing capacity
 
 
 
 
 
 
 
 
$ 1,400,000,000 
 
 
 
Commercial paper outstanding
$ 700,000,000 
$ 368,000,000 
$ 410,000,000 
$ 368,000,000 
$ 290,000,000 
    
 
 
 
 
 
 
Actual debt-to-capital ratio
 
 
 
 
 
 
 
 
0.50 
0.65 
0.49 
0.44 
Minimum ratio of consolidated funds from operations plus interest expense to consolidated interest expense as of balance sheet date
 
 
 
 
 
 
 
 
2.0 to 1.0 
 
 
 
Current ratio of consolidated funds from operations plus interest expense to consolidated interest expense as of balance sheet date
 
 
 
 
 
 
 
 
5.6 to 1.0 
 
 
 
Short Term Debt, Weighted Average Interest Rate During Period
 
 
 
 
 
 
0.39% 
0.11% 
 
 
 
 
Short-Term Debt And Liquidity Short-Term Debt and Liquidity (Commercial Paper) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
$ 539 
$ 2 
Weighted Average Interest Rate
0.45% 
0.80% 
Peak Short Term Borrowings
700 1
21 1
Peak Short Term Borrowings Interest Rate
0.75% 
0.85% 
Ameren (parent) [Domain]
 
 
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
339 
2 
Weighted Average Interest Rate
0.45% 
0.80% 
Peak Short Term Borrowings
452 1
21 1
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
200 
   
Weighted Average Interest Rate
0.45% 
   
Peak Short Term Borrowings
$ 290 1
    1
Peak Short Term Borrowings Interest Rate
0.70% 
   
Long-Term Debt And Equity Financings (Narrative) (Detail) (USD $)
3 Months Ended 1 Months Ended
Mar. 31, 2014
Mar. 31, 2014
Ameren Missouri And Ameren Illinois [Member]
Mar. 31, 2014
Ameren Illinois Company
Mar. 31, 2014
Ameren Illinois Company
Federal Energy Regulatory Commission Restriction [Member]
Mar. 31, 2014
Ameren Illinois Company
Minimum
Federal Energy Regulatory Commission Restriction [Member]
Jan. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds [Member]
Ameren Illinois Company
Apr. 30, 2014
Subsequent Event [Member]
Secured Debt [Member]
Senior Secured Notes, 3.50%, Due 2024 [Member]
Union Electric Company
May 31, 2014
Subsequent Event [Member]
Secured Debt [Member]
Senior Secured Notes550 Due2014 [Member]
Union Electric Company
May 15, 2014
Subsequent Event [Member]
Secured Debt [Member]
Senior Secured Notes550 Due2014 [Member]
Union Electric Company
Long-Term Debt And Equity Financings [Line Items]
 
 
 
 
 
 
 
 
 
Debt Instrument, Face Amount
 
 
$ 1,000,000 
 
 
 
$ 350,000,000 
 
 
Redemptions of Long-term Debt
 
 
 
 
 
163,000,000 
 
104,000,000 
 
Debt Instrument, Interest Rate, Stated Percentage
 
 
 
 
 
 
3.50% 
 
5.50% 
Assumed interest rate
 
6.00% 
 
 
 
 
 
 
 
Dividend rate
 
7.00% 
 
 
 
 
 
 
 
Excess in indebtedness upon default of maturity
25,000,000 
 
 
 
 
 
 
 
 
Common stock equity to total capitalization
 
 
 
55.00% 
30.00% 
 
 
 
 
Proceeds from Issuance of Secured Debt
 
 
 
 
 
 
$ 348,000,000 
 
 
Long-Term Debt And Equity Financings Long-Term Debt and Equity Financings (Schedule of Debt Redemptions (Details) (Ameren Illinois Company, USD $)
1 Months Ended
Mar. 31, 2014
Jan. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds [Member]
Jan. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds [Member]
Series1993590 Due2023 [Member]
Jan. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds [Member]
Series1994A 570 Due 2024 [Member]
Jan. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds [Member]
Series C11993595 Due2026 [Member]
Jan. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds [Member]
Series C21993570 Due2026 [Member]
Jan. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds [Member]
Series1998A 5 Point 40 Due 2028 [Member]
Jan. 31, 2014
Environmental Improvement And Pollution Control Revenue Bonds [Member]
Series1998b540 Due2028 [Member]
Long-Term Debt And Equity Financings [Line Items]
 
 
 
 
 
 
 
 
Debt Instrument, Face Amount
$ 1,000,000 
 
 
 
 
 
 
 
Redemptions of Long-term Debt
 
$ 163,000,000 
$ 32,000,000 1
$ 36,000,000 1
$ 35,000,000 
$ 8,000,000 
$ 19,000,000 
$ 33,000,000 
Long-Term Debt And Equity Financings (Schedule Of Covered Ratio) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Union Electric Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Bonds Issuable
$ 4,018 1
Preferred Stock Issuable
2,272 
Retired bond capacity
729 
Union Electric Company |
Actual Ratio [Member]
 
Long-Term Debt And Equity Financings [Line Items]
 
Restricted payment interest coverage ratio, Actual
4.7 
Dividend Coverage Ratio
118.8 
Ameren Illinois Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Bonds Issuable
3,732 1 2
Preferred Stock Issuable
203 3
Retired bond capacity
$ 454 
Ameren Illinois Company |
Actual Ratio [Member]
 
Long-Term Debt And Equity Financings [Line Items]
 
Restricted payment interest coverage ratio, Actual
7.6 
Dividend Coverage Ratio
2.7 
Minimum |
Union Electric Company |
Minimum Required Ratio [Member]
 
Long-Term Debt And Equity Financings [Line Items]
 
Restricted payment interest coverage ratio, Actual
2.0 4
Dividend Coverage Ratio
2.5 5
Minimum |
Ameren Illinois Company |
Minimum Required Ratio [Member]
 
Long-Term Debt And Equity Financings [Line Items]
 
Restricted payment interest coverage ratio, Actual
2.0 4
Dividend Coverage Ratio
1.5 5
Other Income and Expenses (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Other Nonoperating Income (Expense) [Line Items]
 
 
Allowance for equity funds used during construction
$ 7 1
$ 8 1
Interest income on industrial development revenue bonds
7 1
7 1
Interest and dividend income
2 1
   1
Other
2 1
   1
Total miscellaneous income
18 1
15 1
Donations
5 1
4 1
Other
4 1
4 1
Total miscellaneous expense
9 1
8 1
Union Electric Company
 
 
Other Nonoperating Income (Expense) [Line Items]
 
 
Allowance for equity funds used during construction
7 
7 
Interest income on industrial development revenue bonds
7 
7 
Total miscellaneous income
14 
14 
Donations
2 
2 
Other
2 
3 
Total miscellaneous expense
4 
5 
Ameren Illinois Company
 
 
Other Nonoperating Income (Expense) [Line Items]
 
 
Allowance for equity funds used during construction
   
1 
Interest and dividend income
2 
   
Other
1 
   
Total miscellaneous income
3 
1 
Donations
3 
3 
Other
1 
   
Total miscellaneous expense
$ 4 
$ 3 
Derivative Financial Instruments (Open Gross Derivative Volumes By Commodity Type) (Detail)
Mar. 31, 2014
gal
Dec. 31, 2013
gal
Fuel Oils
 
 
Derivative [Line Items]
 
 
Quantity
53,000,000 1
66,000,000 1
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
137,000,000 
136,000,000 
Power
 
 
Derivative [Line Items]
 
 
Quantity
13,000,000 
14,000,000 
Uranium
 
 
Derivative [Line Items]
 
 
Quantity
827,000 
796,000 
Union Electric Company |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Quantity
53,000,000 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
2,000,000 
3,000,000 
Union Electric Company |
Uranium
 
 
Derivative [Line Items]
 
 
Quantity
827,000 
796,000 
Ameren Illinois Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
109,000,000 
108,000,000 
Ameren Illinois Company |
Power
 
 
Derivative [Line Items]
 
 
Quantity
11,000,000 
11,000,000 
Derivative Financial Instruments (Derivative Instruments Carrying Value) (Detail) (Not Designated As Hedging Instrument [Member], USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Derivative [Line Items]
 
 
Derivative assets
$ 28 1
$ 34 1
Derivative liabilities
172 1
178 1
Fuel Oils |
Other Current Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
5 1
6 1
Fuel Oils |
Other Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
1 1
3 1
Fuel Oils |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 1
2 1
Fuel Oils |
Other Deferred Credits And Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 1
1 1
Natural Gas |
Other Current Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
6 1
2 1
Natural Gas |
Other Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
1 1
 
Natural Gas |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
20 1
32 1
Natural Gas |
Other Deferred Credits And Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
17 1
25 1
Power |
Other Current Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
15 1
23 1
Power |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
14 1
13 1
Power |
Other Deferred Credits And Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
112 1
99 1
Uranium |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
4 1
5 1
Uranium |
Other Deferred Credits And Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
1 1
1 1
Union Electric Company
 
 
Derivative [Line Items]
 
 
Derivative assets
23 1
33 1
Derivative liabilities
23 1
24 1
Union Electric Company |
Fuel Oils |
Other Current Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
5 1
6 1
Union Electric Company |
Fuel Oils |
Other Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
1 1
3 1
Union Electric Company |
Fuel Oils |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 1
2 1
Union Electric Company |
Fuel Oils |
Other Deferred Credits And Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 1
1 1
Union Electric Company |
Natural Gas |
Other Current Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
1 1
1 1
Union Electric Company |
Natural Gas |
Other Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
1 1
 
Union Electric Company |
Natural Gas |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
4 1
5 1
Union Electric Company |
Natural Gas |
Other Deferred Credits And Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
4 1
6 1
Union Electric Company |
Power |
Other Current Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
15 1
23 1
Union Electric Company |
Power |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
6 1
4 1
Union Electric Company |
Uranium |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
4 1
5 1
Union Electric Company |
Uranium |
Other Deferred Credits And Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
1 1
1 1
Ameren Illinois Company
 
 
Derivative [Line Items]
 
 
Derivative assets
5 1
1 1
Derivative liabilities
149 1
154 1
Ameren Illinois Company |
Natural Gas |
Other Current Assets [Member]
 
 
Derivative [Line Items]
 
 
Derivative assets
5 1
1 1
Ameren Illinois Company |
Natural Gas |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
16 1
27 1
Ameren Illinois Company |
Natural Gas |
Other Deferred Credits And Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
13 1
19 1
Ameren Illinois Company |
Power |
Other Current Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
8 1
9 1
Ameren Illinois Company |
Power |
Other Deferred Credits And Liabilities [Member]
 
 
Derivative [Line Items]
 
 
Derivative liabilities
$ 112 1
$ 99 1
Derivative Financial Instruments (Cumulative Amount Of Pretax Net Gains (Losses) On All Derivative Instruments In OCI) (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
$ 248 
$ 216 
Current losses deferred as regulatory assets
220 
156 
Fuel Oils
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
2 
 
Current losses deferred as regulatory assets
1 
 
Fuel Oils |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
   1
2 
Natural Gas
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
6 
 
Current losses deferred as regulatory assets
20 
 
Natural Gas |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(30)2
(55)
Power
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
15 
 
Current losses deferred as regulatory assets
14 
 
Power |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(111)3
(89)
Uranium
 
 
Derivative [Line Items]
 
 
Current losses deferred as regulatory assets
4 
 
Uranium |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(5)4
(6)
Union Electric Company
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
47 
57 
Current losses deferred as regulatory assets
145 
118 
Union Electric Company |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
2 
 
Current losses deferred as regulatory assets
1 
 
Union Electric Company |
Fuel Oils |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
   1
2 
Union Electric Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
1 
 
Current losses deferred as regulatory assets
4 
 
Union Electric Company |
Natural Gas |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(6)2
(10)
Union Electric Company |
Power
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
15 
 
Current losses deferred as regulatory assets
6 
 
Union Electric Company |
Power |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
9 3
19 
Union Electric Company |
Uranium
 
 
Derivative [Line Items]
 
 
Current losses deferred as regulatory assets
4 
 
Union Electric Company |
Uranium |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(5)4
(6)
Ameren Illinois Company
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
201 
159 
Current losses deferred as regulatory assets
75 
38 
Ameren Illinois Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Current gains deferred as regulatory liabilities
5 
 
Current losses deferred as regulatory assets
16 
 
Ameren Illinois Company |
Natural Gas |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
(24)2
(45)
Ameren Illinois Company |
Power
 
 
Derivative [Line Items]
 
 
Current losses deferred as regulatory assets
8 
 
Ameren Illinois Company |
Power |
Regulatory Liabilities Or Assets [Member]
 
 
Derivative [Line Items]
 
 
Cumulative deferred pretax gains (losses)
$ (120)3
$ (108)
Derivative Financial Instruments (Offsetting Derivative Assets and Liabilities) (Details) (Commodity Contract, USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
$ 28 1
$ 34 1
Derivative Instruments
12 
10 
Cash Collateral Received/Posted
   2
   2
Net Amount
16 
24 
Gross Amounts Recognized in the Balance Sheet
172 1
178 1
Derivative Instruments
12 
10 
Cash Collateral Received/Posted
12 2
24 2
Net Amount
148 
144 
Union Electric Company
 
 
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
23 1
33 1
Derivative Instruments
9 
9 
Cash Collateral Received/Posted
   2
   2
Net Amount
14 
24 
Gross Amounts Recognized in the Balance Sheet
23 1
24 1
Derivative Instruments
9 
9 
Cash Collateral Received/Posted
9 2
9 2
Net Amount
5 
6 
Ameren Illinois Company
 
 
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
5 
1 
Derivative Instruments
3 
1 
Cash Collateral Received/Posted
   2
   2
Net Amount
2 
   
Gross Amounts Recognized in the Balance Sheet
149 1
154 1
Derivative Instruments
3 
1 
Cash Collateral Received/Posted
3 2
15 2
Net Amount
$ 143 
$ 138 
Derivative Financial Instruments (Maximum Exposure If Counterparties Fail To Perform On Contracts) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended 3 Months Ended 12 Months Ended 3 Months Ended 12 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Mar. 31, 2014
Union Electric Company
Dec. 31, 2013
Union Electric Company
Mar. 31, 2014
Ameren Illinois Company
Dec. 31, 2012
Ameren Illinois Company
Derivative [Line Items]
 
 
 
 
 
 
Maximum exposure to counterparties related to derivative contracts
$ 14 
$ 13 
$ 9 
$ 12 
$ 5 
$ 1 
Derivative Financial Instruments (Potential Loss On Counterparty Exposures) (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Concentration Risk [Line Items]
 
 
Potential loss on counterparty exposures related to derivative contracts
$ 5 
$ 6 
Union Electric Company
 
 
Concentration Risk [Line Items]
 
 
Potential loss on counterparty exposures related to derivative contracts
3 
6 
Ameren Illinois Company
 
 
Concentration Risk [Line Items]
 
 
Potential loss on counterparty exposures related to derivative contracts
$ 2 
 
Fair Value Measurements (Schedule Of Valuation Process And Unobservable Inputs) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Natural Gas |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.27% 1 2
 
Nodal basis
(0.20)1
 
Credit risk
0.43% 1 2
 
Natural Gas |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
5.00% 1 2
 
Nodal basis
(0.1)1
 
Credit risk
0.43% 1 2
 
Natural Gas |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
1.00% 1 2
 
Nodal basis
(0.1)1
 
Credit risk
0.43% 1 2
 
Natural Gas |
Option Model |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
27.00% 3
 
Nodal basis
(0.30)1
 
Natural Gas |
Option Model |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
102.00% 3
 
Nodal basis
(0.20)1
 
Natural Gas |
Option Model |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
40.00% 3
 
Nodal basis
(0.20)1
 
Natural Gas |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
$ 1 4
 
Natural Gas |
Union Electric Company |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.27% 1 2
 
Nodal basis
(0.20)1
 
Credit risk
0.43% 1 2
 
Natural Gas |
Union Electric Company |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
5.00% 1 2
 
Nodal basis
(0.1)1
 
Credit risk
0.43% 1 2
 
Natural Gas |
Union Electric Company |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
1.00% 1 2
 
Nodal basis
(0.1)1
 
Credit risk
0.43% 1 2
 
Natural Gas |
Union Electric Company |
Option Model |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
   
 
Volatilities
27.00% 3
 
Nodal basis
(0.30)1
 
Natural Gas |
Union Electric Company |
Option Model |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
   
 
Volatilities
102.00% 3
 
Nodal basis
(0.20)1
 
Natural Gas |
Union Electric Company |
Option Model |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
   
 
Volatilities
40.00% 3
 
Nodal basis
(0.20)1
 
Natural Gas |
Union Electric Company |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
1 4
 
Natural Gas |
Ameren Illinois Company |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
   4
 
Natural Gas |
Derivative Liabilities
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(1)4
 
Natural Gas |
Derivative Liabilities |
Union Electric Company
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(1)4
 
Natural Gas |
Derivative Liabilities |
Ameren Illinois Company
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
   4
 
Fuel Oils |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.25% 1 2
0.26% 1 2
Fuel Oils |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.99% 1 2
2.00% 1 2
Fuel Oils |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.63% 1 2
1.00% 1 2
Fuel Oils |
Option Model |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
13.00% 3
10.00% 3
Fuel Oils |
Option Model |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
34.00% 3
35.00% 3
Fuel Oils |
Option Model |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
16.00% 3
16.00% 3
Fuel Oils |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
5 4
8 4
Fuel Oils |
Union Electric Company |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.25% 1 2
0.26% 1 2
Fuel Oils |
Union Electric Company |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.99% 1 2
2.00% 1 2
Fuel Oils |
Union Electric Company |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.63% 1 2
1.00% 1 2
Fuel Oils |
Union Electric Company |
Option Model |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
13.00% 3
10.00% 3
Fuel Oils |
Union Electric Company |
Option Model |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
34.00% 3
35.00% 3
Fuel Oils |
Union Electric Company |
Option Model |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
16.00% 3
16.00% 3
Fuel Oils |
Union Electric Company |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
5 4
8 4
Fuel Oils |
Derivative Liabilities
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(4)4
(3)4
Fuel Oils |
Derivative Liabilities |
Union Electric Company
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(4)4
(3)4
Power |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.35% 1 2
0.39% 1 2
Nodal basis
(6)1
(3)1
Credit risk
0.43% 1 2
2.00% 1 2
Average forward peak and off-peak pricing
27 1
25 1
Estimated auction price
(1,109)3
(1,594)3
Power |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.35% 1 2
0.50% 1 2
Nodal basis
(1)1
(1)1
Credit risk
0.43% 1 2
2.00% 1 2
Average forward peak and off-peak pricing
57 1
51 1
Estimated auction price
2,981 3
945 3
Power |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.35% 1 2
0.42% 1 2
Nodal basis
(3)1
(2)1
Credit risk
0.43% 1 2
2.00% 1 2
Average forward peak and off-peak pricing
33 1
32 1
Estimated auction price
474 3
305 3
Power |
Fundamental Energy Production Model |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
2.00% 3 5
3.00% 3 5
Estimated future gas prices
4 3
4 3
Power |
Fundamental Energy Production Model |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
3.00% 3 5
4.00% 3 5
Estimated future gas prices
6 3
5 3
Power |
Fundamental Energy Production Model |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
3.00% 3 5
4.00% 3 5
Estimated future gas prices
5 3
5 3
Power |
Contract Price Allocation |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
5 3
5 3
Power |
Contract Price Allocation |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
7 3
7 3
Power |
Contract Price Allocation |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
6 3
6 3
Power |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
14 4 6
21 4 7
Power |
Union Electric Company |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.35% 1 2
0.39% 1 2
Nodal basis
(3)1
(3)1
Credit risk
0.43% 1 2
2.00% 1 2
Average forward peak and off-peak pricing
30 1
25 1
Estimated auction price
(1,109)3
(1,594)3
Power |
Union Electric Company |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.35% 1 2
0.50% 1 2
Nodal basis
(1)1
(1)1
Credit risk
0.43% 1 2
2.00% 1 2
Average forward peak and off-peak pricing
57 1
51 1
Estimated auction price
2,981 3
945 3
Power |
Union Electric Company |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.35% 1 2
0.42% 1 2
Nodal basis
(2)1
(2)1
Credit risk
0.43% 1 2
2.00% 1 2
Average forward peak and off-peak pricing
45 1
40 1
Estimated auction price
474 3
305 3
Power |
Union Electric Company |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
14 4 6
21 4 7
Power |
Ameren Illinois Company |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Nodal basis
(6)3
(4)3
Credit risk
0.43% 1 2
2.00% 1 2
Average forward peak and off-peak pricing
27 3
27 3
Power |
Ameren Illinois Company |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Nodal basis
(1)3
0 3
Credit risk
0.43% 1 2
2.00% 1 2
Average forward peak and off-peak pricing
40 3
36 3
Power |
Ameren Illinois Company |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Nodal basis
(3)3
(2)3
Credit risk
0.43% 1 2
2.00% 1 2
Average forward peak and off-peak pricing
32 3
30 3
Power |
Ameren Illinois Company |
Fundamental Energy Production Model |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
2.00% 3 5
3.00% 3 5
Estimated future gas prices
4 3
4 3
Power |
Ameren Illinois Company |
Fundamental Energy Production Model |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
3.00% 3 5
4.00% 3 5
Estimated future gas prices
6 3
5 3
Power |
Ameren Illinois Company |
Fundamental Energy Production Model |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
3.00% 3 5
4.00% 3 5
Estimated future gas prices
5 3
5 3
Power |
Ameren Illinois Company |
Contract Price Allocation |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
5 3
5 3
Power |
Ameren Illinois Company |
Contract Price Allocation |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
7 3
7 3
Power |
Ameren Illinois Company |
Contract Price Allocation |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
6 3
6 3
Power |
Ameren Illinois Company |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
   4 6
   4 7
Power |
Derivative Liabilities
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(124)4 6
(110)4 7
Power |
Derivative Liabilities |
Union Electric Company
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(4)4 6
(2)4 7
Power |
Derivative Liabilities |
Ameren Illinois Company
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(120)4 6
(108)4 7
Uranium |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Average forward pricing
34 3
34 3
Uranium |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Average forward pricing
40 3
41 3
Uranium |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Average forward pricing
35 3
36 3
Uranium |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
   4
   4
Uranium |
Union Electric Company |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Average forward pricing
34 3
34 3
Uranium |
Union Electric Company |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Average forward pricing
40 3
41 3
Uranium |
Union Electric Company |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Average forward pricing
35 3
36 3
Uranium |
Union Electric Company |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
   4
   4
Uranium |
Derivative Liabilities
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(5)4
(6)4
Uranium |
Derivative Liabilities |
Union Electric Company
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
$ (5)4
$ (6)4
Fair Value Measurements (Narrative) (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Valuation adjustments related to net derivative contracts, liabilities
$ 1 
$ 3 
Union Electric Company
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Valuation adjustments related to net derivative contracts, liabilities
1 
1 
Ameren Illinois Company
 
 
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
 
 
Valuation adjustments related to net derivative contracts, liabilities
$ 1 
$ 3 
Fair Value Measurements (Schedule Of Fair Value Hierarchy Of Assets And Liabilities Measured At Fair Value On Recurring Basis) (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
$ 501 1
$ 494 
Assets fair value
529 2
528 2
Excluded receivables, payables, and accrued income, net
2 
 
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
501 1
494 
Assets fair value
524 2
527 2
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
28 2
34 2
Derivative liabilities
172 2
178 2
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
23 2
33 2
Derivative liabilities
23 2
24 2
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 
1 
Derivative liabilities
149 2
154 2
Commodity Contract |
Fuel Oils
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
6 2
9 2
Derivative liabilities
4 2
3 2
Commodity Contract |
Fuel Oils |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
6 2
9 2
Derivative liabilities
4 2
3 2
Commodity Contract |
Natural Gas
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
7 2
2 2
Derivative liabilities
37 2
57 2
Commodity Contract |
Natural Gas |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
2 2
1 2
Derivative liabilities
8 2
11 2
Commodity Contract |
Natural Gas |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 2
1 2
Derivative liabilities
29 2
46 2
Commodity Contract |
Power
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 2
23 2
Derivative liabilities
126 2
112 2
Commodity Contract |
Power |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 2
23 2
Derivative liabilities
6 2
4 2
Commodity Contract |
Power |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
120 2
108 2
Commodity Contract |
Uranium
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
5 2
6 2
Commodity Contract |
Uranium |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
5 2
6 2
Cash and cash equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
3 
Cash and cash equivalents |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
3 
Equity Securities |
U.S. large capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
327 
332 
Equity Securities |
U.S. large capitalization |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
327 
332 
Debt Securities |
Corporate bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
61 
52 
Debt Securities |
Corporate bonds |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
61 
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 |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
2 
Debt Securities |
US treasury and government securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
94 
94 
Debt Securities |
US treasury and government securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
94 
94 
Debt Securities |
Asset-backed Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
14 
10 
Debt Securities |
Asset-backed Securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
14 
10 
Debt Securities |
Other Debt Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
1 
Debt Securities |
Other Debt Securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
1 
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
329 
335 
Assets fair value
330 2
336 2
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
329 
335 
Assets fair value
330 2
336 2
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 2
Derivative liabilities
2 2
3 2
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 2
Derivative liabilities
2 2
3 2
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Fuel Oils
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 2
Derivative liabilities
   2
 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Fuel Oils |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 2
Derivative liabilities
   2
 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Natural Gas
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
2 2
3 2
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Natural Gas |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
2 2
3 2
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Natural Gas |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
 
Derivative liabilities
 
   2
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Cash and cash equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
3 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Cash and cash equivalents |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
3 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Equity Securities |
U.S. large capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
327 
332 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Equity Securities |
U.S. large capitalization |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
327 
332 
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
172 
159 
Assets fair value
179 2
163 2
Significant Other Observable Inputs (Level 2) |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
172 
159 
Assets fair value
174 2
162 2
Significant Other Observable Inputs (Level 2) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
7 2
4 2
Derivative liabilities
36 2
56 2
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
2 2
3 2
Derivative liabilities
7 2
10 2
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
29 2
46 2
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Natural Gas
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
6 2
2 2
Derivative liabilities
34 2
54 2
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Natural Gas |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
1 2
Derivative liabilities
5 2
8 2
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Natural Gas |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 2
1 2
Derivative liabilities
29 2
46 2
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Power
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
2 2
Derivative liabilities
2 2
2 2
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Power |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
2 2
Derivative liabilities
2 2
2 2
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Corporate bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
61 
52 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Corporate bonds |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
61 
52 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Municipal bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
2 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Municipal bonds |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
2 
2 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
US treasury and government securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
94 
94 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
US treasury and government securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
94 
94 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Asset-backed Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
14 
10 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Asset-backed Securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
14 
10 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Other Debt Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
1 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Other Debt Securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
1 
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Assets fair value
20 2
29 2
Significant Other Unobservable Inputs (Level 3) |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Assets fair value
20 2
29 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
20 2
29 2
Derivative liabilities
134 2
119 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
20 2
29 2
Derivative liabilities
14 2
11 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
120 2
108 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Fuel Oils
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 2
8 2
Derivative liabilities
4 2
3 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Fuel Oils |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 2
8 2
Derivative liabilities
4 2
3 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Natural Gas
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
   2
Derivative liabilities
1 2
   2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Natural Gas |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 2
 
Derivative liabilities
1 2
   2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Natural Gas |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
   2
   2
Derivative liabilities
 
   2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Power
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
14 2
21 2
Derivative liabilities
124 2
110 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Power |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
14 2
21 2
Derivative liabilities
4 2
2 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Power |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
120 2
108 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Uranium
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
5 2
6 2
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Uranium |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
$ 5 2
$ 6 2
Fair Value Measurements (Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level Three In The Fair Value Hierarchy) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 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
(2)
 
Purchases
 
1 
Settlements
(2)
(1)
Ending balance
1 
5 
Change in unrealized gains (losses) related to assets/liabilities held at period end
(1)
   
Uranium
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(6)
(2)
Settlements
1 
 
Ending balance
(5)
(2)
Change in unrealized gains (losses) related to assets/liabilities held at period end
   
   
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 
Purchases
(2)
1 
Settlements
2 
 
Ending balance
0 
2 
Change in unrealized gains (losses) related to assets/liabilities held at period end
   
   
Power
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(89)
(100)
Included in regulatory assets/liabilities
(17)
19 
Settlements
(5)
3 
Transfers into Level 3
 
(2)
Transfer out of Level 3
1 
1 
Ending balance
(110)
(79)
Change in unrealized gains (losses) related to assets/liabilities held at period end
(15)
11 
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
(2)
 
Purchases
 
1 
Settlements
(2)
(1)
Ending balance
1 
5 
Change in unrealized gains (losses) related to assets/liabilities held at period end
(1)
   
Union Electric Company |
Uranium
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
(6)
(2)
Settlements
1 
 
Ending balance
(5)
(2)
Change in unrealized gains (losses) related to assets/liabilities held at period end
   
   
Union Electric Company |
Natural Gas
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
Beginning balance
   
   
Included in regulatory assets/liabilities
 
   
Purchases
   
 
Ending balance
   
   
Change in unrealized gains (losses) related to assets/liabilities held at period end
   
   
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
(5)
5 
Settlements
(5)
(13)
Transfers into Level 3
 
(2)
Transfer out of Level 3
1 
1 
Ending balance
10 
2 
Change in unrealized gains (losses) related to assets/liabilities held at period end
(1)
(3)
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 
Purchases
(2)
1 
Settlements
2 
 
Ending balance
0 
2 
Change in unrealized gains (losses) related to assets/liabilities held at period end
   
   
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
(12)
14 
Settlements
   
16 
Transfers into Level 3
 
   
Transfer out of Level 3
 
   
Ending balance
(120)
(81)
Change in unrealized gains (losses) related to assets/liabilities held at period end
$ (14)
$ 14 
Fair Value Measurements (Schedule Of Transfers Between Fair Value Hierarchy Levels) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Derivative [Line Items]
 
 
Net fair value of Level 3 transfers
$ 1 
$ (1)
Power
 
 
Derivative [Line Items]
 
 
Assets Transfers into Level 3
 
2 
Assets Transfers out of Level 3
1 
1 
Power |
Transfer Into/Out of Level 2
 
 
Derivative [Line Items]
 
 
Assets Transfers into Level 3
   
(2)
Assets Transfers out of Level 3
1 
1 
Union Electric Company
 
 
Derivative [Line Items]
 
 
Net fair value of Level 3 transfers
1 
(1)
Union Electric Company |
Power
 
 
Derivative [Line Items]
 
 
Assets Transfers into Level 3
 
2 
Assets Transfers out of Level 3
1 
1 
Union Electric Company |
Power |
Transfer Into/Out of Level 2
 
 
Derivative [Line Items]
 
 
Assets Transfers into Level 3
   
(2)
Assets Transfers out of Level 3
1 
1 
Ameren Illinois Company |
Power
 
 
Derivative [Line Items]
 
 
Assets Transfers into Level 3
 
   
Assets Transfers out of Level 3
 
   
Fair Value Measurements (Schedule Of Carrying Amounts And Estimated Fair Values Of Long-Term Debt And Preferred Stock) (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Fair Value
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
$ 6,530 1
$ 6,584 1
Preferred stock
119 1
118 1
Fair Value |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
4,200 
4,124 
Preferred stock
71 
71 
Fair Value |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
1,903 
2,028 
Preferred stock
48 
47 
Carrying Amount
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
5,874 1
6,038 1
Preferred stock
142 1
142 1
Carrying Amount |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
3,758 
3,757 
Preferred stock
80 
80 
Carrying Amount |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
1,692 
1,856 
Preferred stock
$ 62 
$ 62 
Commitments And Contingencies (Callaway Energy Center) (Detail) (USD $)
3 Months Ended
Mar. 31, 2014
Commitments And Contingencies [Line Items]
 
Threshold for which a retrospective assessment for a covered loss is necessary
$ 375,000,000 
Annual payment in the event of an incident at any licensed commercial reactor
19,000,000 
Aggregate maximum assessment per incident under Price-Anderson liability provisions of Atomic Energy Act
128,000,000 
Maximum annual payment in calendar year per reactor incident under Price Andersen Liability Provisions of Atomic Energy Act
19,000,000 
Amount of coverage in excess of primary property liability coverage
2,250,000,000.00 
Sub-limit of Amount of Coverage in Excess of Primary Property Liability Coverage for Non-Nuclear Events
1,700,000,000 
Amount of weekly indemnity coverage commencing eight weeks after power outage
4,500,000.0 
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 secondary weekly indemnity coverage for prolonged nuclear plant outage in excess of primary indemnity coverage
900,000 
Inflationary adjustment prescribed by most recent Price-Anderson Act renewal, in years
5 years 
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period
3,240,000,000 
Public Liability
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
13,616,000,000 1
Maximum Assessments for Single Incidents
128,000,000 
Public Liability And Nuclear Worker Liability - American Nuclear Insurers [Member]
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
375,000,000 
Public Liability And Nuclear Worker Liability - Pool Participation [Member]
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
13,241,000,000 2
Maximum Assessments for Single Incidents
128,000,000 3
Property Damage
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
2,750,000,000 
Maximum Assessments for Single Incidents
23,000,000 
Property Damage - Nuclear Electric Insurance Ltd [Member]
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
2,250,000,000 4
Maximum Assessments for Single Incidents
23,000,000 5
Sub-limit of Amount of Coverage in Excess of Primary Property Liability Coverage for Non-Nuclear Events
200,000,000 
Property Damage European Mutual Association for Nuclear Insurance [Member]
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
500,000,000 6
Amount of primary property liability coverage
500,000,000 
Replacement Power - Nuclear Electric Insurance Ltd [Member]
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
490,000,000 7
Maximum Assessments for Single Incidents
9,000,000 5
Amount of weekly indemnity coverage thereafter not exceeding policy limit
490,000,000 
Sub-limit of for non-nuclear events
327,600,000 
Replacement Power - Energy Risk Assurance Company [Member]
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
64,000,000 8
Amount of weekly indemnity coverage thereafter not exceeding policy limit
$ 3,600,000 
Commitments And Contingencies (Other Obligations) (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Long-term Purchase Commitment [Line Items]
 
Other obligations
$ 6,251 
Union Electric Company
 
Long-term Purchase Commitment [Line Items]
 
Other obligations
4,273 
Ameren Illinois Company
 
Long-term Purchase Commitment [Line Items]
 
Other obligations
$ 1,908 
Commitments And Contingencies (Environmental Matters) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Minimum
 
Loss Contingencies [Line Items]
 
Estimated capital costs to comply with existing and known federal and state air emissions regulations
$ 275 
Maximum
 
Loss Contingencies [Line Items]
 
Estimated capital costs to comply with existing and known federal and state air emissions regulations
350 
Former Coal Tar Distillery |
Union Electric Company
 
Loss Contingencies [Line Items]
 
Range of possible loss, minimum
2.0 
Range of possible loss maximum
5.0 
Accrual for environmental loss contingencies
2.0 
Former Coal Ash Landfill |
Ameren Illinois Company
 
Loss Contingencies [Line Items]
 
Range of possible loss, minimum
0.5 
Range of possible loss maximum
6.0 
Accrual for environmental loss contingencies
0.5 
Manufactured Gas Plant
 
Loss Contingencies [Line Items]
 
Range of possible loss, minimum
269.0 
Range of possible loss maximum
345.0 
Accrual for environmental loss contingencies
269.0 1
Manufactured Gas Plant |
Union Electric Company
 
Loss Contingencies [Line Items]
 
Number of remediation sites
1 
Range of possible loss, minimum
3.0 
Range of possible loss maximum
4.0 
Accrual for environmental loss contingencies
3.0 1
Manufactured Gas Plant |
Ameren Illinois Company
 
Loss Contingencies [Line Items]
 
Number of remediation sites
44 
Range of possible loss, minimum
266.0 
Range of possible loss maximum
341.0 
Accrual for environmental loss contingencies
266.0 1
Other Environmental |
Ameren Illinois Company
 
Loss Contingencies [Line Items]
 
Accrual for environmental loss contingencies
0.8 
Sauget Area Two |
Union Electric Company
 
Loss Contingencies [Line Items]
 
Range of possible loss, minimum
1.0 
Range of possible loss maximum
2.5 
Loss Contingency, Loss in Period
0.7 
Accrual for environmental loss contingencies
1.0 
Substation in St Charles, Missouri |
Union Electric Company
 
Loss Contingencies [Line Items]
 
Range of possible loss, minimum
1.6 
Range of possible loss maximum
4.5 
Accrual for environmental loss contingencies
$ 1.6 
Commitments And Contingencies (Pumped-Storage Hydroelectric Facility Breach) (Detail) (Union Electric Company, USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Union Electric Company
 
Loss Contingencies [Line Items]
 
Insurance settlements receivable
$ 68 
Callaway Energy Center (Narrative) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Mar. 31, 2014
mill
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Nuclear Waste Matters [Line Items]
 
 
 
 
Miscellaneous accounts and notes receivable
$ 201 
$ 196 
 
 
Nuclear Plant [Member]
 
 
 
 
Nuclear Waste Matters [Line Items]
 
 
 
 
Number of mills charged for NWF fee
1 
 
 
 
Miscellaneous accounts and notes receivable
15 
15 
 
 
Assumed life of plant, in years
40 years 
 
 
 
Annual decommissioning costs included in costs of service
 
$ 7 
$ 7 
$ 7 
Retirement Benefits (Narrative) (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
Defined benefit plan, estimated future employer contributions in each of the next five years
$ 270 
Minimum
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
Defined benefit plan, estimated future employer contributions in each of the next five years
20 
Maximum
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
Defined benefit plan, estimated future employer contributions in each of the next five years
$ 100 
Retirement Benefits (Components Of Net Periodic Benefit Cost) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Pension Benefit [Member]
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Service cost
$ 21 
$ 24 
Interest cost
49 
40 
Expected return on plan assets
(57)
(54)
Prior service cost (benefit)
0 
(1)
Actuarial loss
12 
22 
Net periodic benefit cost
25 
31 
Postretirement Benefit Costs [Member]
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Service cost
5 
6 
Interest cost
13 
12 
Expected return on plan assets
(16)
(16)
Prior service cost (benefit)
(1)
(1)
Actuarial loss
(1)
2 
Net periodic benefit cost
$ 0 
$ 3 
Retirement Benefits (Summary Of Benefit Plan Costs Incurred) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Pension Benefit [Member]
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Net periodic benefit cost
$ 25 1
$ 31 1
Pension Benefit [Member] |
Union Electric Company
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Net periodic benefit cost
17 
18 
Pension Benefit [Member] |
Ameren Illinois Company
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Net periodic benefit cost
8 
10 
Pension Benefit [Member] |
Other
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Net periodic benefit cost
0 
3 
Postretirement Benefits [Member]
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Net periodic benefit cost
0 1
3 1
Postretirement Benefits [Member] |
Union Electric Company
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Net periodic benefit cost
1 
2 
Postretirement Benefits [Member] |
Ameren Illinois Company
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Net periodic benefit cost
(1)
1 
Postretirement Benefits [Member] |
Other
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
Net periodic benefit cost
$ 0 
$ 0 
Divestiture Transactions and Discontinued Operations (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 3 Months Ended 1 Months Ended 3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Dec. 31, 2013
Mar. 31, 2013
New Ameren Energy Resources Company, LLC
Mar. 31, 2014
New Ameren Energy Resources Company, LLC
Mar. 14, 2013
New Ameren Energy Resources Company, LLC
Mar. 31, 2014
Notes Payable, Other Payables [Member]
New Ameren Energy Resources Company, LLC
Dec. 31, 2013
Notes Payable, Other Payables [Member]
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
Mar. 31, 2014
Ameren Energy Marketing Company [Member]
Mar. 31, 2014
Guarantee Type, Other [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
Escrow Deposit, Reserve Period
2 years 
 
 
 
 
 
 
 
 
 
 
 
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
 
 
 
155 
 
 
 
 
 
 
 
 
Discontinued operations deferred tax expense
 
 
 
98 
 
 
 
 
 
 
 
 
Discontinued operations deferred tax benefit
 
 
 
63 
 
 
 
 
 
 
 
 
Loss from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
1 
199 
 
 
 
 
 
 
 
 
 
 
Asset retirement obligations
373 
 
369 
 
 
 
 
 
 
 
 
 
Range of possible loss maximum
 
 
 
 
34.0 
 
 
 
 
 
 
 
Other deferred credits and liabilities
554 
 
538 
 
29 
 
 
 
 
 
 
 
Accounts and wages payable
559 
 
806 
 
5 
 
 
 
 
 
 
 
Notes, Loans and Financing Receivable, Net, Noncurrent
 
 
 
 
 
 
27 
18 
 
 
 
 
Buyer's indemnification guarantee obligation
 
 
 
 
 
25 
 
 
 
 
 
 
Guarantees Outstanding
184 
 
 
 
 
 
 
 
 
 
171 
13 
Guarantees, Maximum Exposure
 
 
 
 
 
 
 
 
 
 
17 
 
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
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
Operating revenues
$ 1 
$ 264 
Operating expenses
(2)
(415)1
Operating loss
(1)
(151)
Other loss
   
(2)
Interest charges
   
(11)
Loss before income taxes
(1)
(164)
Income tax expense
   
(35)
Loss from discontinued operations, net of taxes
(1)
(199)
New Ameren Energy Resources Company, LLC
 
 
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
Impairment of Long-Lived Assets to be Disposed of
 
$ 155 
Divestiture Transactions and Discontinued Operations (Components of Assets and Liabilities) (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2014
Dec. 31, 2013
Mar. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
 
 
 
Asset retirement obligations
$ 373 
$ 369 
 
Assets of discontinued operations
 
 
 
Cash and cash equivalents
   
   
25 
Accounts receivable and unbilled revenue
   
5 
 
Materials and supplies
   
5 
 
Property and plant, net
   
142 
 
Accumulated deferred income taxes, net(a)
15 1
13 1
 
Total assets of discontinued operations
15 
165 
 
Liabilities of discontinued operations
 
 
 
Accounts payable and other current obligations
2 
5 
 
Asset retirement obligations(b)
31 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
$ 31 
$ 31 
 
Segment Information (Schedule Of Segment Reporting Information By Segment) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Dec. 31, 2013
Segment Reporting Information [Line Items]
 
 
 
External revenues
$ 1,594 
$ 1,475 
 
Net income (loss) attributable to Ameren Corporation from continuing operations
97 
54 
 
Total assets
21,166 
 
21,042 
Assets of discontinued operations (Note 12)
15 
 
165 
Union Electric Company
 
 
 
Segment Reporting Information [Line Items]
 
 
 
External revenues
811 
789 
 
Intersegment revenues
6 
7 
 
Net income (loss) attributable to Ameren Corporation from continuing operations
47 
40 
 
Total assets
12,948 
 
12,904 
Ameren Illinois Company
 
 
 
Segment Reporting Information [Line Items]
 
 
 
External revenues
774 
684 
 
Intersegment revenues
   
   
 
Net income (loss) attributable to Ameren Corporation from continuing operations
53 
31 
 
Total assets
7,640 
 
7,454 
Other
 
 
 
Segment Reporting Information [Line Items]
 
 
 
External revenues
9 
2 
 
Intersegment revenues
1 
2 
 
Net income (loss) attributable to Ameren Corporation from continuing operations
(3)
(17)
 
Total assets
898 
 
752 
Intersegment Eliminations
 
 
 
Segment Reporting Information [Line Items]
 
 
 
External revenues
   
   
 
Intersegment revenues
(7)
(9)
 
Net income (loss) attributable to Ameren Corporation from continuing operations
   
   
 
Total assets
(335)
 
(233)
Consolidated, Continuing Operations
 
 
 
Segment Reporting Information [Line Items]
 
 
 
External revenues
1,594 
1,475 
 
Intersegment revenues
   
   
 
Net income (loss) attributable to Ameren Corporation from continuing operations
97 
54 
 
Total assets
$ 21,151 1
 
$ 20,877 1