Divestiture Transactions and Discontinued Operations (Tables)

3 Months Ended

Mar. 31, 2013

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block]

The following table presents the components of discontinued operations in Ameren's consolidated statement of income (loss) for the three months ended March 31, 2013, and 2012:

	Three Months
	2013				2012
Operating revenues	$	264			$	246
Operating expenses	(415		)	(a)	(826		)	(b)
Operating (loss)	(151		)		(580		)
Other income (loss)	(2		)		—
Interest charges	(11		)		(15		)
Loss before income taxes	(164		)		(595		)
Income tax (expense) benefit	(35		)		153
Loss from discontinued operations, net of taxes	$	(199	)		$	(442	)

(a) Includes a noncash pretax 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.

(b) Includes a noncash pretax asset impairment charge of $628 million to reduce the carrying value of AERG’s Duck Creek energy center to its estimated fair value under held and used accounting guidance.

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, 2013, and December 31, 2012:

	March 31, 2013		December 31, 2012
Current assets of discontinued operations
Cash and cash equivalents	$	25	$	25
Accounts receivable and unbilled revenue	103		102
Materials and supplies	117		134
Mark-to-market derivative assets	101		102
Property and plant, net	607		748
Accumulated deferred income taxes, net	412		373
Other assets	135		116
Total current assets of discontinued operations	$	1,500	$	1,600
Current liabilities of discontinued operations
Accounts payable and other current obligations	$	138	$	133
Mark-to-market derivative liabilities	82		63
Long-term debt, net	824		824
Asset retirement obligations	86		78
Pension and other postretirement benefits	39		40
Other liabilities	29		28
Total current liabilities of discontinued operations	$	1,198	$	1,166
Accumulated other comprehensive gain(a)	$	12	$	19
Noncontrolling interest(b)	$	8	$	8

(a) Accumulated other comprehensive gain related to discontinued operations remains in “Accumulated other comprehensive gain (loss)” on Ameren’s March 31, 2013, and December 31, 2012, balance sheets. This balance relates to New AER assets and liabilities that will be realized or removed from Ameren’s balance sheet either before or at the closing of the New AER divestiture.

(b) The 20% ownership interest of EEI not owned by Ameren remains in “Noncontrolling interests” on Ameren’s March 31, 2013, and December 31, 2012, balance sheets. This noncontrolling interest will be removed from Ameren’s balance sheet at the closing of the New AER divestiture.

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, 2013, at an assumed interest rate of 6% and dividend rate of 7%.

	Required Interest Coverage Ratio(a)	Actual Interest Coverage Ratio		Bonds Issuable(b)		Required Dividend Coverage Ratio(c)	Actual Dividend Coverage Ratio		Preferred Stock Issuable
Ameren Missouri	≥2.0	4.7	$	4,304		≥2.5	128.1	$	2,454
Ameren Illinois	≥2.0	7.2		3,499	(d)	≥1.5	2.7		203

(a) Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.

(b) Amount of bonds issuable based either on requir

Ameren Energy Generating Company [Member]

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Schedule Of Coverage Ratios

Genco Indenture Provisions

Genco’s indenture includes provisions that require Genco to maintain certain interest coverage and debt-to-capital ratios in order for Genco to pay dividends, to make principal or interest payments on subordinated borrowings, to make loans to or investments in affiliates, or to incur additional external, third-party indebtedness. The following table summarizes these ratios for the 12 months ended and as of March 31, 2013:

	Required Ratio	Actual Ratio
Restricted payment interest coverage ratio(a)	≥1.75	2.3
Additional indebtedness interest coverage ratio(b)	≥2.50	2.3
Additional indebtedness debt-to-capital ratio(b)	≤60%	50	%

(a) As of the date of the restricted payment, as defined, the minimum ratio must have been achieved for the most recently ended four fiscal quarters and projected by management to be achieved for each of the subsequent four six-month periods. Investments in the non-state-regulated subsidiary money pool and repayments of non-state-regulated subsidiary money pool borrowings are not subject to this incurrence test.

(b) Ratios must be computed on a pro forma basis consider