Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax benefit from discontinued operations	$ 12		$ 24
Operating revenues from discontinued operations		406		849
Loss from discontinued operation before income taxes		208		383
Pensions and benefits	2,234		2,234		2,614
Edison Mission Energy
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of days after bankruptcy filing for settlement transaction (days)			150 days
Number of days for completion of settlement transaction agreement from petition date (days)			210 days
Joint tax liability	189		189
Receivables from EME	235		235
Edison Mission Energy | Pension Plans
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pensions and benefits	80		80
Deconsolidated charges recorded in accumulated other comprehensive income			34
Plan Support Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net receivable under plan support agreement	46		46
Retirement liabilities assumed under plan support agreement	104		104
Estimated loss under plan support agreement			$ 150