Derivative Instruments and Hedging Activities (Balance Sheet Disclosures) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	$ 91		$ 106
Long-Term, Derivative Assets	111		128
Short-Term, Derivative Liabilities	170		268
Long-Term, Derivative Liabilities	558		547
Electric Utility | Commodity Contracts
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	45	[1]	65
Long-Term, Derivative Assets	59	[1]	70
Derivative Assets, Total	104	[1]	135
Short-Term, Derivative Liabilities	173	[1]	266
Long-Term, Derivative Liabilities	796	[1]	805
Derivative Liabilities, Total	969	[1]	1,071
Net Asset (Liability)	(865)	[1]	(936)
Electric Utility | Commodity Contracts | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	69	[1]	86
Long-Term, Derivative Assets	75	[1]	85
Derivative Assets, Total	144	[1]	171
Short-Term, Derivative Liabilities	245	[1]	303
Long-Term, Derivative Liabilities	830	[1]	856
Derivative Liabilities, Total	1,075	[1]	1,159
Net Asset (Liability)	(931)	[1]	(988)
Electric Utility | Commodity Contracts | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	(24)	[1]	(21)
Long-Term, Derivative Assets	(16)	[1]	(15)
Derivative Assets, Total	(40)	[1]	(36)
Short-Term, Derivative Liabilities	(72)	[1]	(37)
Long-Term, Derivative Liabilities	(34)	[1]	(51)
Derivative Liabilities, Total	(106)	[1]	(88)
Net Asset (Liability)	66	[1]	52
Competitive Power Generation
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	46		40
Long-Term, Derivative Assets	52		59
Derivative Assets, Total	98		99
Short-Term, Derivative Liabilities	0		1
Long-Term, Derivative Liabilities	114		90
Derivative Liabilities, Total	114		91
Net Asset (Liability)	(16)		8
Competitive Power Generation | Trading and Non-trading activities
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	381		348
Long-Term, Derivative Assets	157		144
Derivative Assets, Total	538		492
Short-Term, Derivative Liabilities	297		260
Long-Term, Derivative Liabilities	211		173
Derivative Liabilities, Total	508		433
Net Asset (Liability)	30		59
Competitive Power Generation | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	28		31
Long-Term, Derivative Assets	2		1
Derivative Assets, Total	30		32
Short-Term, Derivative Liabilities	24		26
Long-Term, Derivative Liabilities	2		1
Derivative Liabilities, Total	26		27
Net Asset (Liability)	4		5
Competitive Power Generation | Trading activities
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	329		276
Long-Term, Derivative Assets	153		142
Derivative Assets, Total	482		418
Short-Term, Derivative Liabilities	272		232
Long-Term, Derivative Liabilities	92		79
Derivative Liabilities, Total	364		311
Net Asset (Liability)	118		107
Competitive Power Generation | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	(335)	[2]	(308)	[2]
Long-Term, Derivative Assets	(105)	[2]	(85)	[2]
Derivative Assets, Total	(440)	[2]	(393)	[2]
Short-Term, Derivative Liabilities	(297)	[2]	(259)	[2]
Long-Term, Derivative Liabilities	(97)	[2]	(83)	[2]
Derivative Liabilities, Total	(394)	[2]	(342)	[2]
Net Asset (Liability)	(46)	[2]	(51)	[2]
Competitive Power Generation | Commodity Contracts | Cash flow hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	24		41
Long-Term, Derivative Assets	2		1
Derivative Assets, Total	26		42
Short-Term, Derivative Liabilities	1		2
Long-Term, Derivative Liabilities	3		3
Derivative Liabilities, Total	4		5
Net Asset (Liability)	22		37
Competitive Power Generation | Interest Rate Contracts | Cash flow hedges
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	114		90
Derivative Liabilities, Total	114		90
Net Asset (Liability)	$ (114)		$ (90)

[1] 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.

[2] 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.