Variable Interest Entities (Details) (USD $)	6 Months Ended									6 Months Ended		6 Months Ended		3 Months Ended	1 Months Ended								3 Months Ended		6 Months Ended
	Jun. 30, 2012		Dec. 31, 2011	Feb. 13, 2012 Mission Energy Holding Company	Feb. 13, 2012 Broken Bow I, LLC Agreement to Sell Ownership, Upon Satisfaction of Specific Conditions MW	Feb. 13, 2012 Crofton Bluffs Agreement to Sell Ownership, Upon Satisfaction of Specific Conditions MW	Feb. 13, 2012 Cedro Hill Wind, LLC MW	Feb. 13, 2012 Mountain Wind Power Project MW	Feb. 13, 2012 Mountain Wind Power II Project MW	Jun. 30, 2012 Capistrano Wind Partners	Feb. 13, 2012 Capistrano Wind Partners	Jun. 30, 2012 Capistrano Wind Partners Mission Energy Holding Company	Feb. 13, 2012 Capistrano Wind Partners Agreement to Sell Ownership, Upon Satisfaction of Specific Conditions	Jun. 30, 2012 SCE Trust I	May 31, 2012 SCE Trust I Trust Securities	Jun. 30, 2012 SCE Trust I Trust Securities	Jun. 30, 2012 SCE Trust I Series F	May 31, 2012 SCE Trust I Series F	Jun. 30, 2012 Variable Interest Entity, Primary Beneficiary	Dec. 31, 2011 Variable Interest Entity, Primary Beneficiary	Jun. 30, 2012 Variable Interest Entity, Primary Beneficiary EMG Wind Projects projects MW	Dec. 31, 2011 Variable Interest Entity, Primary Beneficiary EMG Wind Projects MW projects	Jun. 30, 2012 Variable Interest Entity, Not Primary Beneficiary SCE Power Purchase Contracts agreements MW contracts	Jun. 30, 2011 Variable Interest Entity, Not Primary Beneficiary SCE Power Purchase Contracts	Jun. 30, 2012 Variable Interest Entity, Not Primary Beneficiary SCE Power Purchase Contracts agreements MW contracts	Jun. 30, 2011 Variable Interest Entity, Not Primary Beneficiary SCE Power Purchase Contracts
Details of projects or entities
Number of projects (in projects)																							16		16
Number of projects consolidated (in projects)																					16	13
Power generating capacity for majority interest (in megawatts)																					861	570	3,820		3,820
Summarized balance sheet information of VIEs
Current assets	$ 4,438,000,000		$ 4,484,000,000																$ 118,000,000	$ 36,000,000
Net property, plant and equipment	4,535,000,000		4,547,000,000																1,107,000,000	675,000,000
Other long-term assets	717,000,000		706,000,000																22,000,000	5,000,000
Total assets	49,388,000,000		48,039,000,000																1,247,000,000	716,000,000
Current liabilities	4,223,000,000		4,348,000,000																34,000,000	28,000,000
Long-term debt net of current portion	13,658,000,000		13,689,000,000																175,000,000	57,000,000
Deferred revenues																			173,000,000	69,000,000
Long-term derivative liabilities	558,000,000		547,000,000																22,000,000	0
Other long-term liabilities	2,640,000,000		2,476,000,000																37,000,000	22,000,000
Total liabilities	37,443,000,000		36,953,000,000																441,000,000	176,000,000
Noncontrolling interests	2,000,000,000		1,031,000,000																240,000,000	2,000,000
Assets serving as collateral for the debt obligations																			472,000,000	136,000,000
Sale of ownership (in megawatts)					80	40	150	61	80
Outside investors contribution											238,000,000		140,000,000
Ownership percentage (as a percent)												100.00%
Preferred equity interests to receive percent of cash available for distribution (as a percent)										100.00%
Cash available for distribution includes percent of tax benefits to be realized (as a percent)										90.00%
Preferred investment made				4,000,000
Tax effect upon transfer of assets to Capistrano Wind Partners	21,000,000	[1]
Power purchase agreement with tolling agreement (in agreements)																							6		6
Power purchase agreement with qualified facilities (in contracts)																							10		10
Payments to unconsolidated VIEs, power purchase contracts																							57,000,000	83,000,000	134,000,000	169,000,000
Unconsolidated Trust
Security dividend rate, (as a percent)															5.625%
Liquidation value (in dollars per share)															$ 25			$ 2,500
Liquidation preference															475,000,000
Common stock														10,000	10,000
Preference stock																475,000,000	475,000,000	475,000,000
Dividend income and distributions														$ 3,000,000

[1] Common stock was reduced by $21 million during the six months ended June 30, 2012 due to a new tax basis in the assets transferred to Capistrano Wind Partners. The tax basis allocation to the transferred assets was updated during the three months ended June 30, 2012. For further information, see Note 3.