Derivative Instruments (Balance Sheet Disclosures) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	$ 111		$ 129
Long-Term, Derivative Assets	81		85
Short-Term, Derivative Liabilities	107		126
Long-Term, Derivative Liabilities	1,014		939
Southern California Edison
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	111		129
Long-Term, Derivative Assets	81		85
Short-Term, Derivative Liabilities	107		126
Long-Term, Derivative Liabilities	1,014		939
Southern California Edison | Commodity Contracts | Electric Utility
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	111		129
Long-Term, Derivative Assets	81		85
Derivative Assets, Total	192		214
Short-Term, Derivative Liabilities	107		126
Long-Term, Derivative Liabilities	1,014		939
Derivative Liabilities, Total	1,121		1,065	[1]
Net Asset (Liability)	929		851
Southern California Edison | Commodity Contracts | Electric Utility | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	133		151
Long-Term, Derivative Assets	85		91
Derivative Assets, Total	218		242
Short-Term, Derivative Liabilities	149		186
Long-Term, Derivative Liabilities	1,025		954
Derivative Liabilities, Total	1,174		1,140	[1]
Net Asset (Liability)	956		898
Southern California Edison | Commodity Contracts | Electric Utility | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	(22)		(22)
Long-Term, Derivative Assets	(4)		(6)
Derivative Assets, Total	(26)		(28)
Short-Term, Derivative Liabilities	(22)		(22)
Long-Term, Derivative Liabilities	(4)		(6)
Derivative Liabilities, Total	(26)		(28)	[1]
Net Asset (Liability)	0		0
Southern California Edison | Commodity Contracts | Electric Utility | Cash Collateral Posted
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	0	[1]	0	[1]
Long-Term, Derivative Assets	0	[1]	0	[1]
Derivative Assets, Total	0	[1]	0	[1]
Short-Term, Derivative Liabilities	(20)	[1]	(38)	[1]
Long-Term, Derivative Liabilities	(7)	[1]	(9)	[1]
Derivative Liabilities, Total	(27)	[1]	(47)	[1]
Net Asset (Liability)	(27)	[1]	(47)	[1]
Southern California Edison | Power Purchase Agreement
Fair Value of Derivative Instruments
Fair value of derivative liabilities	$ 10		$ 8

[1] In addition, SCE has posted $10 million and $8 million of collateral that is not offset against the derivative liabilities and is reflected in "Other current assets" on the March 31, 2013 and December 31, 2012 consolidated balance sheets, respectively.