Derivative Instruments and Hedging Activities (Balance Sheet Disclosures) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	$ 76		$ 106
Long-Term, Derivative Assets	117		131
Short-Term, Derivative Liabilities	109		268
Long-Term, Derivative Liabilities	717		547
Electric Utility | Commodity Contracts
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	37	[1]	65
Long-Term, Derivative Assets	74	[1]	70
Derivative Assets, Total	111	[1]	135
Short-Term, Derivative Liabilities	128	[1]	266
Long-Term, Derivative Liabilities	983	[1]	805
Derivative Liabilities, Total	1,111	[1]	1,071
Net Asset (Liability)	(1,000)	[1]	(936)
Electric Utility | Commodity Contracts | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	55	[1]	86
Long-Term, Derivative Assets	80	[1]	85
Derivative Assets, Total	135	[1]	171
Short-Term, Derivative Liabilities	177	[1]	303
Long-Term, Derivative Liabilities	1,002	[1]	856
Derivative Liabilities, Total	1,179	[1]	1,159
Net Asset (Liability)	(1,044)	[1]	(988)
Electric Utility | Commodity Contracts | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	(18)	[1]	(21)
Long-Term, Derivative Assets	(6)	[1]	(15)
Derivative Assets, Total	(24)	[1]	(36)
Short-Term, Derivative Liabilities	(49)	[1]	(37)
Long-Term, Derivative Liabilities	(19)	[1]	(51)
Derivative Liabilities, Total	(68)	[1]	(88)
Net Asset (Liability)	44	[1]	52
Competitive Power Generation
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	39		40
Long-Term, Derivative Assets	43		62
Derivative Assets, Total	82		102
Short-Term, Derivative Liabilities	1		1
Long-Term, Derivative Liabilities	125		90
Derivative Liabilities, Total	126		91
Net Asset (Liability)	(44)		11
Competitive Power Generation | Trading and Non-trading activities
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	360		341
Long-Term, Derivative Assets	148		143
Derivative Assets, Total	508		484
Short-Term, Derivative Liabilities	297		254
Long-Term, Derivative Liabilities	225		169
Derivative Liabilities, Total	522		423
Net Asset (Liability)	(14)		61
Competitive Power Generation | Economic hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	25		24
Long-Term, Derivative Assets	1		0
Derivative Assets, Total	26		24
Short-Term, Derivative Liabilities	23		20
Long-Term, Derivative Liabilities	1		0
Derivative Liabilities, Total	24		20
Net Asset (Liability)	2		4
Competitive Power Generation | Trading activities
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	321		277
Long-Term, Derivative Assets	145		142
Derivative Assets, Total	466		419
Short-Term, Derivative Liabilities	265		232
Long-Term, Derivative Liabilities	98		79
Derivative Liabilities, Total	363		311
Net Asset (Liability)	103		108
Competitive Power Generation | Netting and Collateral
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	(321)	[2]	(301)	[2]
Long-Term, Derivative Assets	(105)	[2]	(81)	[2]
Derivative Assets, Total	(426)	[2]	(382)	[2]
Short-Term, Derivative Liabilities	(296)	[2]	(253)	[2]
Long-Term, Derivative Liabilities	(100)	[2]	(79)	[2]
Derivative Liabilities, Total	(396)	[2]	(332)	[2]
Net Asset (Liability)	(30)	[2]	(50)	[2]
Competitive Power Generation | Commodity Contracts | Cash flow hedges
Fair Value of Derivative Instruments
Short-Term, Derivative Assets	14		40
Long-Term, Derivative Assets	2		1
Derivative Assets, Total	16		41
Short-Term, Derivative Liabilities	9		2
Long-Term, Derivative Liabilities	1		0
Derivative Liabilities, Total	10		2
Net Asset (Liability)	6		39
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	125		90
Derivative Liabilities, Total	125		90
Net Asset (Liability)	$ (125)		$ (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.