Derivative Instruments and Hedging Activities (Balance Sheet Disclosures) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	$ 129	$ 65
Long-Term, Derivative Assets	85	70
Short-Term, Derivative Liabilities	126	266
Long-Term, Derivative Liabilities	939	456
Southern California Edison
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	129	65
Long-Term, Derivative Assets	85	70
Short-Term, Derivative Liabilities	126	266
Long-Term, Derivative Liabilities	939	805
Southern California Edison | Commodity Contracts | Electric Utility
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	129	65
Long-Term, Derivative Assets	85	70
Derivative Assets, Total	214	135
Short-Term, Derivative Liabilities	126	266	[1]
Long-Term, Derivative Liabilities	939	805	[1]
Derivative Liabilities, Total	1,065	1,071	[1]
Net Asset (Liability)	851	936
Southern California Edison | Commodity Contracts | Electric Utility | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	151	86
Long-Term, Derivative Assets	91	85
Derivative Assets, Total	242	171
Short-Term, Derivative Liabilities	186	303	[1]
Long-Term, Derivative Liabilities	954	856	[1]
Derivative Liabilities, Total	1,140	1,159	[1]
Net Asset (Liability)	898	988
Southern California Edison | Commodity Contracts | Electric Utility | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	(22)	(21)
Long-Term, Derivative Assets	(6)	(15)
Derivative Assets, Total	(28)	(36)
Short-Term, Derivative Liabilities	(60)	(37)	[1]
Long-Term, Derivative Liabilities	(15)	(51)	[1]
Derivative Liabilities, Total	(75)	(88)	[1]
Net Asset (Liability)	(47)	(52)
Edison Mission Energy | Southern California Edison | Power Purchase Agreement
Fair Value of Derivative Instruments
Fair value of derivative liabilities		$ 349

[1] Included in 2011 is a power purchase agreement between SCE and EME with a fair market value of $349 million, which was eliminated in the Edison International consolidated financial statements.