Schedule I - Condensed Financial Information Of Parent

12 Months Ended

Dec. 31, 2012

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Condensed Financial Information Of Parent

SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT AMEREN CORPORATION CONDENSED STATEMENT OF INCOME (LOSS) AND COMPREHENSIVE INCOME (LOSS) For the Years Ended December 31, 2012, 2011 and 2010
(In millions)	2012			2011			2010
Operating revenues	$	—		$	—		$	—
Impairment and other charges	—			—			372
Operating expenses	22			15			24
Operating loss	(22		)	(15		)	(396		)
Equity in earnings (loss) of subsidiaries	(954		)	527			535
Interest income from affiliates	40			44			28
Miscellaneous expense	4			4			3
Interest charges	39			41			56
Income tax (benefit)	(5		)	(8		)	(31		)
Net income (loss)	(974		)	519			139
Other Comprehensive Income (Loss), Net of Taxes:
Unrealized net gain (loss) on derivative hedging instruments, net of income taxes (benefit) of $12, $1, and $(1), respectively	22			3			(2		)
Reclassification adjustments for derivative (gains) losses included in net income, net of income taxes (benefit) of $1, $(3), and $5, respectively	(4		)	4			(8		)
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $22, $(32), and $6, respectively	32			(46		)	4
Total other comprehensive income (loss), net of taxes	50			(39		)	(6		)
Comprehensive Income (Loss)	$	(924	)	$	480		$	133

SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT AMEREN CORPORATION CONDENSED BALANCE SHEET
(In millions)	December 31, 2012			December 31, 2011
Assets:
Cash and cash equivalents	$	23		$	3
Advances to money pool	316			340
Accounts and notes receivable - affiliates	31			57
Other current assets	49			—
Total current assets	419			400
Investments in subsidiaries	5,962			7,482
Note receivable - affiliates	462			425
Other non-current assets	320			333
Total assets	$	7,163		$	8,640
Liabilities and Stockholders’ Equity:
Short-term debt	$	—		$	148
Accounts payable - affiliates	10			13
Other current liabilities	33			62
Total current liabilities	43			223
Long-term debt	424			424
Other deferred credits and liabilities	80			74
Total liabilities	547			721
Commitments and Contingencies
Stockholders’ Equity:
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 242.6	2			2
Other paid-in capital, principally premium on common stock	5,616			5,598
Retained earnings	1,006			2,369
Accumulated other comprehensive income (loss)	(8		)	(50		)
Total stockholders’ equity	6,616			7,919
Total liabilities and stockholders’ equity	$	7,163		$	8,640

SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT AMEREN CORPORATION CONDENSED STATEMENT OF CASH FLOWS For the Years Ended December 31, 2012, 2011 and 2010
(In millions)	2012			2011			2010
Net cash flows provided by operating activities	$	532		$	804		$	241
Cash flows from investing activities:
Money pool advances, net	24			(276		)	18
Notes receivable - affiliates, net	(20		)	358			242
Investments in subsidiaries	(2		)	(94		)	(13		)
Distributions from subsidiaries	21			3			1
Other	(5		)	(5		)	—
Net cash flows provided by (used in) investing activities	18			(14		)	248
Cash flows from financing activities:
Dividends on common stock	(382		)	(375		)	(368		)
Short-term debt and credit facility borrowings, net	(148		)	(481		)	(221		)
Issuances of common stock	—			65			80
Net cash flows used in financing activities	(530		)	(791		)	(509		)
Net change in cash and cash equivalents	$	20		$	(1	)	$	(20	)
Cash and cash equivalents at beginning of year	3			4			24
Cash and cash equivalents at the end of year	$	23		$	3		$	4
Cash dividends received from consolidated subsidiaries	$	610		$	730		$	368
Noncash financing activity – dividends on common stock	$	(7	)	$	—		$	—

BASIS OF PRESENTATION

Ameren Corporation (parent company only) is a public utility holding company that conducts substantially all of its business operations through its subsidiaries. As specified in Note 5 - Long-term Debt and Equity Financings under Part II, Item 8, of this report, there are restrictions on Ameren Corporation’s (parent company only) ability to obtain funds from certain of its subsidiaries through dividends, loans or advances. In accordance with authoritative accounting guidance, Ameren Corporation (parent company only) has accounted for wholly owned subsidiaries using the equity method. These financial statements are presented on a condensed basis. Additional disclosures relating to the parent company financial statements are included within the combined notes under Part II, Item 8, of this report.

SHORT-TERM DEBT AND LIQUIDITY

See Note 4 - Short-term Debt and Liquidity under Part II, Item 8, of this report for a description and details of short-term debt and liquidity needs of Ameren Corporation (parent company only).

LONG-TERM OBLIGATIONS

See Note 5 - Long-term Debt and Equity Financings under Part II, Item 8, of this report for a description and details of long-term obligations of Ameren Corporation (parent company only).

COMMITMENTS AND CONTINGENCIES

See Note 14 - Related Party Transactions and Note 15 - Commitments and Contingencies under Part II Item 8, of this report for a description of all material contingencies and guarantees outstanding of Ameren Corporation (parent company only).

IMPAIRMENTS

In December 2012, Ameren determined that it intends to, and it is probable that it will, exit its Merchant Generation business before the end of the previously estimated useful lives of that business's long-lived assets. This determination resulted from Ameren's analysis of the current and projected future financial condition of its Merchant Generation segment and its conclusion that this segment is no longer a core component of its future business strategy. In consideration of this determination, Ameren has begun planning to reduce, and ultimately eliminate, the Merchant Generation segment's reliance on Ameren's financial support and shared services support. Ameren's date and method of exit from the Merchant Generation business is currently uncertain.

As a result of the announcement that Ameren intends to exit the Merchant Generation segment before the end of the Merchant Generation's long-lived assets' previously estimated useful lives, Ameren determined that estimated undiscounted cash flows during the period in which it expects to continue to own certain energy centers would be insufficient to recover the carrying value of those energy centers. Accordingly, in the fourth quarter of 2012, Ameren Corporation (parent company only) recorded a noncash pretax impairment charge of $1.88 billion to reduce its investment in certain of the Merchant Generation segment's coal and natural gas-fired energy centers to their estimated fair values. This charge was included within "Equity in earnings (loss) of subsidiaries" in the Ameren Corporation (parent company only) Condensed Statement of Income (Loss) and Comprehensive Income (Loss) for the year ended December 31, 2012.

During 2010, Ameren's Merchant Generation reporting unit failed step one of the interim goodwill impairment test, as the reporting unit's carrying value exceeded its estimated fair value. Based on the results of step two of the goodwill impairment test, Ameren Corporation (parent company only) recorded a noncash impairment charge of $345 million, which represented all of the goodwill assigned to Ameren's Merchant Generation reporting unit recorded at Ameren Corporation (parent company only).

Prior to 2010, Ameren's Merchant Generation expected to use its SO₂ emission allowances for ongoing operations. In July 2010, the EPA issued the proposed CSAPR, which would have restricted the use of existing SO₂ emission allowances. As a result, Merchant Generation no longer expected all of its SO₂ emission allowances would be used in operations. Therefore, during 2010, Ameren Corporation (parent company only) recorded a $27 million pretax impairment charge to reduce the carrying value of SO₂ emission allowances associated with Merchant Generation recorded at Ameren Corporation (parent company only), to their estimated fair value.

See Note 17 - Impairment and Other Charges under Part II, Item 8, of this report for additional information on the impairment charges recognized in 2012 and 2010.