SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended									12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011		Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets:
Cash and cash equivalents	$ 888	$ 888				$ 1,221					$ 888	$ 1,221	$ 948
Affiliate receivables	8	8				4					8	4
Total current assets	1,323	1,323				1,941					1,323	1,941
Investments in subsidiaries	534	534				523					534	523
Other long-term assets	128	128				222					128	222
Total Assets	7,520	7,520				8,323					7,520	8,323
Liabilities and Shareholders' Equity:
Affiliate payables	34	34				187					34	187
Total current liabilities	820	820				548					820	548
Liabilities subject to compromise	3,959	3,959				0					3,959	0
Long-term debt	749	749				4,855					749	4,855
Deferred taxes	81	81				0					81	0
Total Liabilities	6,788	6,788				6,659					6,788	6,659
Total EME Common Shareholder's Equity	732	732				1,664					732	1,664	2,821	2,837
Total Liabilities and Equity	7,520	7,520				8,323					7,520	8,323
CONDENSED STATEMENTS OF INCOME
Operating revenues		280	340	324	343	381		437	400	435	1,287	1,653	1,788
Operating expenses											1,615	2,351	1,594
Operating loss		(102)	(78)	(100)	(48)	(717)		30	(44)	33	(328)	(698)	194
Equity in income from continuing operations of subsidiaries											46	85	104
Income (loss) from continuing operations before reorganization items and income taxes											(594)	(888)	65
Reorganization items	43										43	0	0
Income tax benefit											160	(441)	(16)
Net Income (Loss)		(561)	(162)	(104)	(82)	(1,060)	[1]	33	(32)	(20)	(909)	(1,079)	163
Other comprehensive income (loss), net of tax
Other comprehensive loss, net of tax											(44)	(63)	(109)
Comprehensive Income (Loss) Attributable to Edison Mission Energy Common Shareholder											(969)	(1,141)	55
CONDENSED STATEMENTS OF CASH FLOWS
Operating activities											(513)	626	606
Investing activities											(461)	(678)	(562)
Net increase (decrease) in cash and cash equivalents											(333)	273	268
Cash and cash equivalents at beginning of period from continuing operations					1,221					948	1,221	948	680
Cash and cash equivalents at end of period from continuing operations	888	888				1,221					888	1,221	948
Edison Mission Energy
Assets:
Cash and cash equivalents	328	328				738					328	738	427
Affiliate receivables	363	363				3					363	3
Other current assets	15	15				5					15	5
Total current assets	706	706				746					706	746
Investments in subsidiaries	5,015	5,015				6,408					5,015	6,408
Other long-term assets	260	260				199					260	199
Total Assets	5,981	5,981				7,353					5,981	7,353
Liabilities and Shareholders' Equity:
Accounts payable and accrued liabilities	18	18				72					18	72
Affiliate payables	132	132				539					132	539
Total current liabilities	150	150				611					150	611
Liabilities subject to compromise	5,256	5,256				0					5,256	0
Long-term debt	0	0				3,700					0	3,700
Long-term affiliate debt	0	0				1,335					0	1,335
Deferred taxes	131	131				45					131	45
Total Liabilities	5,537	5,537				5,691					5,537	5,691
Total EME Common Shareholder's Equity	444	444				1,662					444	1,662
Total Liabilities and Equity	5,981	5,981				7,353					5,981	7,353
CONDENSED STATEMENTS OF INCOME
Operating revenues											9	4	4
Operating expenses											(111)	(146)	(114)
Operating loss											(102)	(142)	(110)
Equity in income from continuing operations of subsidiaries											(289)	(788)	463
Interest Expense And Other											(375)	(383)	(355)
Income (loss) from continuing operations before reorganization items and income taxes											(766)	(1,313)	(2)
Reorganization items											37	0	0
Income tax benefit											122	(235)	(166)
Net Income (Loss)											(925)	(1,078)	164
Other comprehensive income (loss), net of tax
Other comprehensive loss, net of tax											(44)	(63)	(109)
Comprehensive Income (Loss) Attributable to Edison Mission Energy Common Shareholder											(969)	(1,141)	55
CONDENSED STATEMENTS OF CASH FLOWS
Operating activities											(497)	(53)	576
Net cash used in financing activities											(9)	(2)	(245)
Investing activities											96	366	(84)
Net increase (decrease) in cash and cash equivalents											(410)	311	247
Cash and cash equivalents at beginning of period from continuing operations					738					427	738	427	180
Cash and cash equivalents at end of period from continuing operations	328	328				738					328	738	427
Cash dividends received from subsidiaries											$ 45	$ 903	$ 125

[1] Reflects $704 million pre-tax ($424 million after tax) of asset impairment charges. For more information, see Note 13—Asset Impairments and Other Charges. In addition, the amount reflects a $1,032 million pre-tax ($623 million after tax) impairment charge related to Homer City. For more information, see Note 14—Discontinued Operations.