Income Taxes (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Effective Tax Rate
Income from continuing operations before income taxes	$ 115,000,000	$ 281,000,000
Provision for income tax at federal statutory rate of 35%	40,000,000	98,000,000
Increase (decrease) in income tax from:
State tax benefit - net of federal tax expense	(9,000,000)	0
Production and housing credits	(19,000,000)	(18,000,000)
Property-related	(10,000,000)	(11,000,000)
Other	(2,000,000)	(4,000,000)
Total income tax expense from continuing operations	0	65,000,000
Effective tax rate		23.00%
Federal statutory rate (as a percent)	35.00%	35.00%
Homer City
Tax Election at Homer City
Tax reduction due to change in tax treatment of entity	1,000,000,000
Federal and state net operating loss carryforwards and federal tax credit carryfowards	1,200,000,000
IRS Examination
Settlement of Tax Disputes
Estimated potential future federal tax payment as of the balance sheet date, including interest and penalties, based on a proposed adjustment	194,000,000
Penalty for understatement of tax liability (as a percent)	40.00%
IRS Examination | Southern California Edison Company
Settlement of Tax Disputes
Estimated potential future federal tax payment as of the balance sheet date, including interest and penalties, based on a proposed adjustment	$ 94,000,000