CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Operating Revenues	$ 1,287		$ 1,653		$ 1,788
Operating Expenses
Fuel	602		530		531
Plant operations	495		571		538
Plant operating leases	75		75		75
Depreciation and amortization	268		289		229
Asset impairments and other charges	28	[1]	714	[1]	44	[1]
Administrative and general	147		172		177
Total operating expenses	1,615		2,351		1,594
Operating income (loss)	(328)		(698)		194
Other Income (Expense)
Equity in income from unconsolidated affiliates	46		86		104
Dividend income	12		30		19
Interest income	2		1		2
Interest expense	(326)		(322)		(262)
Other income, net	0		15		8
Total other income (expense)	(266)		(190)		(129)
Income (loss) from continuing operations before reorganization items and income taxes	(594)		(888)		65
Reorganization items	43		0		0
Provision (benefit) for income taxes	160		(441)		(16)
Income (Loss) from Continuing Operations	(797)		(447)		81
Income (Loss) from Operations of Discontinued Subsidiaries, net of tax (Note 14)	(112)		(632)		82
Net Income (Loss)	(909)		(1,079)		163
Net (Income) Loss Attributable to Noncontrolling Interests (Note 3)	(16)		1		1
Net Income (Loss)	(925)		(1,078)		164
Amounts Attributable to Common Shareholder
Income (loss) from continuing operations, net of tax	(813)		(446)		82
Income (loss) from discontinued operations, net of tax	(112)		(632)		82
Net Income (Loss)	(925)		(1,078)		164
Midwest Generation LLC
Operating Revenues	892		1,286		1,479
Operating Expenses
Fuel	582		512		519
Plant operations	369		457		447
Depreciation and amortization	128		158		155
Asset impairments and other charges	14	[1]	653	[1]	48	[1]
Administrative and general	18		22		22
Impairment of loan to affiliate (Note 15)	1,378		0		0
Total operating expenses	2,489		1,802		1,191
Operating income (loss)	(1,597)		(516)		288
Other Income (Expense)
Interest and other income	110		114		117
Interest expense	(33)		(40)		(48)
Total other income (expense)	77		74		69
Income (loss) from continuing operations before reorganization items and income taxes	(1,520)		(442)		357
Reorganization items	6		0		0
Provision (benefit) for income taxes	(62)		(172)		142
Net Income (Loss)	(1,464)		(270)		215
Net Income (Loss)	(1,464)		(270)		215
Amounts Attributable to Common Shareholder
Net Income (Loss)	$ (1,464)		$ (270)		$ 215

[1] The fair value of long-lived assets as determined using the discounted cash flow models discussed below qualify as Level 3 in the fair value hierarchy.