Fair Value Measurements (Recurring Fair Value Measurements) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011		Mar. 31, 2011	Dec. 31, 2010
Assets at Fair Value
Money market funds	$ 5			$ 21
Nuclear decommissioning trusts	3,810		3,853	3,592	3,657		3,619	3,480
Liabilities at Fair Value
Percentage of equity investments located in the United States (as a percent)	67.00%			70.00%
Collateralized mortgage obligations and other asset backed securities	44			22
Receivables (payables) net related to investments	(17)			25
Cash surrender value of life insurance	98			81
Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,090			1,899
Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	714			756
U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	549			580
Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	382			317
Level 3
Assets at Fair Value
Total assets	113
Liabilities at Fair Value
Total liabilities	852
Fair Value, Measurements, Recurring | Level 1
Assets at Fair Value
Money market funds	5	[1]			21	[1]
Derivative contracts	0				0
Long-term disability plan	8				8
Nuclear decommissioning trusts	2,481				2,332
Total assets	2,494	[2]			2,361	[2]
Liabilities at Fair Value
Derivative contracts	0				0
Total liabilities	0				0
Net assets (liabilities)	2,494				2,361
Fair Value, Measurements, Recurring | Level 1 | Electricity
Assets at Fair Value
Derivative contracts	0				0
Liabilities at Fair Value
Derivative contracts	0				0
Fair Value, Measurements, Recurring | Level 1 | Natural gas
Assets at Fair Value
Derivative contracts					0
Liabilities at Fair Value
Derivative contracts	0				0
Fair Value, Measurements, Recurring | Level 1 | CRRs
Assets at Fair Value
Derivative contracts	0				0
Fair Value, Measurements, Recurring | Level 1 | Tolling
Assets at Fair Value
Derivative contracts					0
Liabilities at Fair Value
Derivative contracts	0				0
Fair Value, Measurements, Recurring | Level 1 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,090	[3]			1,899	[3]
Fair Value, Measurements, Recurring | Level 1 | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	0				0
Fair Value, Measurements, Recurring | Level 1 | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	389				433
Fair Value, Measurements, Recurring | Level 1 | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	0	[4]			0	[4]
Fair Value, Measurements, Recurring | Level 1 | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	2	[5]			0	[5]
Fair Value, Measurements, Recurring | Level 2
Assets at Fair Value
Money market funds	0	[1]			0	[1]
Derivative contracts	2				5
Long-term disability plan	0				0
Nuclear decommissioning trusts	1,346				1,235
Total assets	1,348	[2]			1,240	[2]
Liabilities at Fair Value
Derivative contracts	194				239
Total liabilities	194				239
Net assets (liabilities)	1,154				1,001
Fair Value, Measurements, Recurring | Level 2 | Electricity
Assets at Fair Value
Derivative contracts	2				0
Liabilities at Fair Value
Derivative contracts	0				5
Fair Value, Measurements, Recurring | Level 2 | Natural gas
Assets at Fair Value
Derivative contracts					5
Liabilities at Fair Value
Derivative contracts	194				234
Fair Value, Measurements, Recurring | Level 2 | CRRs
Assets at Fair Value
Derivative contracts	0				0
Fair Value, Measurements, Recurring | Level 2 | Tolling
Assets at Fair Value
Derivative contracts					0
Liabilities at Fair Value
Derivative contracts	0				0
Fair Value, Measurements, Recurring | Level 2 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	0	[3]			0	[3]
Fair Value, Measurements, Recurring | Level 2 | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	714				756
Fair Value, Measurements, Recurring | Level 2 | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	160				147
Fair Value, Measurements, Recurring | Level 2 | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	382	[4]			317	[4]
Fair Value, Measurements, Recurring | Level 2 | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	90	[5]			15	[5]
Fair Value, Measurements, Recurring | Level 3
Assets at Fair Value
Money market funds	0	[1]			0	[1]
Derivative contracts	113				133
Long-term disability plan	0				0
Nuclear decommissioning trusts	0				0
Total assets	113	[2]			133	[2]
Liabilities at Fair Value
Derivative contracts	852				887
Total liabilities	852				887
Net assets (liabilities)	(739)				(754)
Fair Value, Measurements, Recurring | Level 3 | Electricity
Assets at Fair Value
Derivative contracts	21				1
Liabilities at Fair Value
Derivative contracts	21				65
Fair Value, Measurements, Recurring | Level 3 | Natural gas
Assets at Fair Value
Derivative contracts					0
Liabilities at Fair Value
Derivative contracts	28				23
Fair Value, Measurements, Recurring | Level 3 | CRRs
Assets at Fair Value
Derivative contracts	92				122
Fair Value, Measurements, Recurring | Level 3 | Tolling
Assets at Fair Value
Derivative contracts					10
Liabilities at Fair Value
Derivative contracts	803				799
Fair Value, Measurements, Recurring | Level 3 | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	0	[3]			0	[3]
Fair Value, Measurements, Recurring | Level 3 | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	0				0
Fair Value, Measurements, Recurring | Level 3 | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	0				0
Fair Value, Measurements, Recurring | Level 3 | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	0	[4]			0	[4]
Fair Value, Measurements, Recurring | Level 3 | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	0	[5]			0	[5]
Fair Value, Measurements, Recurring | Netting and Collateral
Assets at Fair Value
Money market funds	0	[1],[6]			0	[1],[6]
Derivative contracts	(11)	[6]			(3)	[6]
Long-term disability plan	0	[6]			0	[6]
Nuclear decommissioning trusts	0	[6]			0	[6]
Total assets	(11)	[2],[6]			(3)	[2],[6]
Liabilities at Fair Value
Derivative contracts	(77)	[6]			(55)	[6]
Total liabilities	(77)	[6]			(55)	[6]
Net assets (liabilities)	66	[6]			52	[6]
Fair Value, Measurements, Recurring | Netting and Collateral | Electricity
Assets at Fair Value
Derivative contracts	(11)	[6]			0	[6]
Liabilities at Fair Value
Derivative contracts	(11)	[6]			(2)	[6]
Fair Value, Measurements, Recurring | Netting and Collateral | Natural gas
Assets at Fair Value
Derivative contracts					(3)	[6]
Liabilities at Fair Value
Derivative contracts	(66)	[6]			(53)	[6]
Fair Value, Measurements, Recurring | Netting and Collateral | CRRs
Assets at Fair Value
Derivative contracts		[6]			0	[6]
Fair Value, Measurements, Recurring | Netting and Collateral | Tolling
Assets at Fair Value
Derivative contracts					0	[6]
Liabilities at Fair Value
Derivative contracts	0	[6]			0	[6]
Fair Value, Measurements, Recurring | Netting and Collateral | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	0	[3],[6]			0	[3],[6]
Fair Value, Measurements, Recurring | Netting and Collateral | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	0	[6]			0	[6]
Fair Value, Measurements, Recurring | Netting and Collateral | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	0	[6]			0	[6]
Fair Value, Measurements, Recurring | Netting and Collateral | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	0	[4],[6]			0	[4],[6]
Fair Value, Measurements, Recurring | Netting and Collateral | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	0	[5],[6]			0	[5],[6]
Fair Value, Measurements, Recurring | Total
Assets at Fair Value
Money market funds	5	[1]			21	[1]
Derivative contracts	104				135
Long-term disability plan	8				8
Nuclear decommissioning trusts	3,827				3,567
Total assets	3,944	[2]			3,731	[2]
Liabilities at Fair Value
Derivative contracts	969				1,071
Total liabilities	969				1,071
Net assets (liabilities)	2,975				2,660
Fair Value, Measurements, Recurring | Total | Electricity
Assets at Fair Value
Derivative contracts	12				1
Liabilities at Fair Value
Derivative contracts	10				68
Fair Value, Measurements, Recurring | Total | Natural gas
Assets at Fair Value
Derivative contracts					2
Liabilities at Fair Value
Derivative contracts	156				204
Fair Value, Measurements, Recurring | Total | CRRs
Assets at Fair Value
Derivative contracts	92				122
Fair Value, Measurements, Recurring | Total | Tolling
Assets at Fair Value
Derivative contracts					10
Liabilities at Fair Value
Derivative contracts	803				799
Fair Value, Measurements, Recurring | Total | Stocks
Assets at Fair Value
Nuclear decommissioning trusts	2,090	[3]			1,899	[3]
Fair Value, Measurements, Recurring | Total | Municipal bonds
Assets at Fair Value
Nuclear decommissioning trusts	714				756
Fair Value, Measurements, Recurring | Total | U.S. government and agency securities
Assets at Fair Value
Nuclear decommissioning trusts	549				580
Fair Value, Measurements, Recurring | Total | Corporate bonds
Assets at Fair Value
Nuclear decommissioning trusts	382	[4]			317	[4]
Fair Value, Measurements, Recurring | Total | Short-term investments, primarily cash equivalents
Assets at Fair Value
Nuclear decommissioning trusts	$ 92	[5]			$ 15	[5]

[1] Money market funds are included in cash and cash equivalents on SCE's consolidated balance sheets.

[2] Excludes other investments of $98 million and $81 million at June 30, 2012 and December 31, 2011, respectively, primarily related to the cash surrender value of company owned life insurance investments which are used to fund certain executive benefits including deferred compensation.

[3] Approximately 67% and 70% of the equity investments were located in the United States at June 30, 2012 and December 31, 2011, respectively.

[4] At June 30, 2012 and December 31, 2011, corporate bonds were diversified and included collateralized mortgage obligations and other asset backed securities of $44 million and $22 million, respectively.

[5] Excludes net payables of $17 million and net receivables of $25 million at June 30, 2012 and December 31, 2011, respectively, of interest and dividend receivables as well as receivables and payables related to pending securities sales and purchases.

[6] Represents the netting of assets and liabilities under master netting agreements and cash collateral across the levels of the fair value hierarchy. Netting among positions classified within the same level is included in that level.