Derivative Instruments and Hedging Activities (Balance Sheet Disclosures) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	$ 90		$ 106
Long-Term, Derivative Assets	117		128
Short-Term, Derivative Liabilities	255		268
Long-Term, Derivative Liabilities	803		547
Electric Utility | Commodity Contracts
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	51		65
Long-Term, Derivative Assets	65		70
Derivative Assets, Total	116		135
Short-Term, Derivative Liabilities	254	[1]	266
Long-Term, Derivative Liabilities	1,135	[1]	805
Derivative Liabilities, Total	1,389	[1]	1,071
Net Asset (Liability)	(1,273)		(936)
Electric Utility | Commodity Contracts | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	65		86
Long-Term, Derivative Assets	72		85
Derivative Assets, Total	137		171
Short-Term, Derivative Liabilities	338	[1]	303
Long-Term, Derivative Liabilities	1,153	[1]	856
Derivative Liabilities, Total	1,491	[1]	1,159
Net Asset (Liability)	(1,354)		(988)
Electric Utility | Commodity Contracts | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	(14)		(21)
Long-Term, Derivative Assets	(7)		(15)
Derivative Assets, Total	(21)		(36)
Short-Term, Derivative Liabilities	(84)	[1]	(37)
Long-Term, Derivative Liabilities	(18)	[1]	(51)
Derivative Liabilities, Total	(102)	[1]	(88)
Net Asset (Liability)	81		52
Competitive Power Generation
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	39		40
Long-Term, Derivative Assets	52		59
Derivative Assets, Total	91		99
Short-Term, Derivative Liabilities	1		1
Long-Term, Derivative Liabilities	79		90
Derivative Liabilities, Total	80		91
Net Asset (Liability)	11		8
Competitive Power Generation | Trading and Non-trading activities
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	516		348
Long-Term, Derivative Assets	185		144
Derivative Assets, Total	701		492
Short-Term, Derivative Liabilities	408		260
Long-Term, Derivative Liabilities	200		173
Derivative Liabilities, Total	608		433
Net Asset (Liability)	93		59
Competitive Power Generation | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	57		31
Long-Term, Derivative Assets	3		1
Derivative Assets, Total	60		32
Short-Term, Derivative Liabilities	47		26
Long-Term, Derivative Liabilities	2		1
Derivative Liabilities, Total	49		27
Net Asset (Liability)	11		5
Competitive Power Generation | Trading activities
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	408		276
Long-Term, Derivative Assets	180		142
Derivative Assets, Total	588		418
Short-Term, Derivative Liabilities	360		232
Long-Term, Derivative Liabilities	117		79
Derivative Liabilities, Total	477		311
Net Asset (Liability)	111		107
Competitive Power Generation | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	(477)	[2]	(308)	[2]
Long-Term, Derivative Assets	(133)	[2]	(85)	[2]
Derivative Assets, Total	(610)	[2]	(393)	[2]
Short-Term, Derivative Liabilities	(407)	[2]	(259)	[2]
Long-Term, Derivative Liabilities	(121)	[2]	(83)	[2]
Derivative Liabilities, Total	(528)	[2]	(342)	[2]
Net Asset (Liability)	(82)	[2]	(51)	[2]
Competitive Power Generation | Commodity Contracts | Cash flow hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	51		41
Long-Term, Derivative Assets	2		1
Derivative Assets, Total	53		42
Short-Term, Derivative Liabilities	1		2
Long-Term, Derivative Liabilities	3		3
Derivative Liabilities, Total	4		5
Net Asset (Liability)	49		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	78		90
Derivative Liabilities, Total	78		90
Net Asset (Liability)	$ (78)		$ (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.