Derivative Instruments and Hedging Activities (Balance Sheet Disclosures) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	$ 106		$ 133
Long-Term, Derivative Assets	128		437
Short-Term, Derivative Liabilities	268		217
Long-Term, Derivative Liabilities	547		468
Competitive Power Generation
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	40		46
Long-Term, Derivative Assets	59		70
Derivative Assets, Total	99		116
Short-Term, Derivative Liabilities	1		6
Long-Term, Derivative Liabilities	90		19
Derivative Liabilities, Total	91		25
Net Asset (Liability)	8		91
Competitive Power Generation | Trading and Non-trading activities
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	348		315
Long-Term, Derivative Assets	144		107
Derivative Assets, Total	492		422
Short-Term, Derivative Liabilities	260		229
Long-Term, Derivative Liabilities	173		54
Derivative Liabilities, Total	433		283
Net Asset (Liability)	59		139
Competitive Power Generation | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	31		77
Long-Term, Derivative Assets	1		2
Derivative Assets, Total	32		79
Short-Term, Derivative Liabilities	26		71
Long-Term, Derivative Liabilities	1		0
Derivative Liabilities, Total	27		71
Net Asset (Liability)	5		8
Competitive Power Generation | Trading activities
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	276		184
Long-Term, Derivative Assets	142		103
Derivative Assets, Total	418		287
Short-Term, Derivative Liabilities	232		148
Long-Term, Derivative Liabilities	79		29
Derivative Liabilities, Total	311		177
Net Asset (Liability)	107		110
Competitive Power Generation | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	(308)	[1]	(269)	[1]
Long-Term, Derivative Assets	(85)	[1]	(37)	[1]
Derivative Assets, Total	(393)	[1]	(306)	[1]
Short-Term, Derivative Liabilities	(259)	[1]	(223)	[1]
Long-Term, Derivative Liabilities	(83)	[1]	(35)	[1]
Derivative Liabilities, Total	(342)	[1]	(258)	[1]
Net Asset (Liability)	(51)	[1]	(48)	[1]
Commodity Contracts | Electric Utility
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	65		87
Long-Term, Derivative Assets	70		367
Derivative Assets, Total	135		454
Short-Term, Derivative Liabilities	266	[2]	212
Long-Term, Derivative Liabilities	805	[2]	449
Derivative Liabilities, Total	1,071	[2]	661
Net Asset (Liability)	(936)		(207)
Commodity Contracts | Electric Utility | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	86		87
Long-Term, Derivative Assets	85		367
Derivative Assets, Total	171		454
Short-Term, Derivative Liabilities	303	[2]	216
Long-Term, Derivative Liabilities	856	[2]	449
Derivative Liabilities, Total	1,159	[2]	665
Net Asset (Liability)	(988)		(211)
Commodity Contracts | Electric Utility | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	21
Long-Term, Derivative Assets	15
Derivative Assets, Total	36
Short-Term, Derivative Liabilities	37	[2]	4
Long-Term, Derivative Liabilities	51	[2]
Derivative Liabilities, Total	88	[2]	4
Net Asset (Liability)	(52)		(4)
Commodity Contracts | Competitive Power Generation
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	41		54
Long-Term, Derivative Assets	1		2
Derivative Assets, Total	42		56
Short-Term, Derivative Liabilities	2		10
Long-Term, Derivative Liabilities	3		9
Derivative Liabilities, Total	5		19
Net Asset (Liability)	37		37
Interest Rate Contracts | Competitive Power Generation
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	0		0
Long-Term, Derivative Assets	0		0
Derivative Assets, Total	0		0
Short-Term, Derivative Liabilities	0		0
Long-Term, Derivative Liabilities	90		16
Derivative Liabilities, Total	90		16
Net Asset (Liability)	$ (90)		$ (16)

[1] Netting of derivative receivables and derivative payables and the related cash collateral received and paid is permitted when a legally enforceable master netting agreement exists with a derivative counterparty.

[2] Includes the fair value of derivatives with SCE's consolidated affiliates; however, in Edison International’s consolidated financial statements, the fair value of such derivatives is eliminated.