Other Investments (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	$ 2,303,000,000	$ 2,185,000,000
Summary of changes in the fair value of the trust
Balance at beginning of period	3,480,000,000	3,140,000,000	2,524,000,000
Gross realized gains	108,000,000	125,000,000	242,000,000
Gross realized losses	(17,000,000)	(4,000,000)	(147,000,000)
Unrealized gains (losses) - net	(7,000,000)	148,000,000	526,000,000
Other-than-temporary impairments	(47,000,000)	(27,000,000)	(111,000,000)
Interest, dividends, contributions and other	75,000,000	98,000,000	106,000,000
Balance at end of period	3,592,000,000	3,480,000,000	3,140,000,000
Proceeds from sale of securities	2,773,000,000	1,432,000,000	2,217,000,000
Unrealized holding gains, net of losses	1,300,000,000	1,300,000,000
Stocks
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments	0
Amortized Cost	865,000,000	895,000,000
Summary of changes in the fair value of the trust
Balance at beginning of period	2,029,000,000
Balance at end of period	1,899,000,000
Municipal bonds
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments	2051
Amortized Cost	625,000,000	706,000,000
Summary of changes in the fair value of the trust
Balance at beginning of period	790,000,000
Balance at end of period	756,000,000
U.S. government and agency securities
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments	2041
Amortized Cost	516,000,000	270,000,000
Summary of changes in the fair value of the trust
Balance at beginning of period	288,000,000
Balance at end of period	580,000,000
Corporate bonds
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments	2054
Amortized Cost	259,000,000	288,000,000
Summary of changes in the fair value of the trust
Balance at beginning of period	346,000,000
Balance at end of period	317,000,000
Short-term investments and receivables/payables
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments	One-year
Amortized Cost	38,000,000	26,000,000
Summary of changes in the fair value of the trust
Balance at beginning of period	27,000,000
Balance at end of period	40,000,000
Southern California Edison Company
Fair Value Disclosures:
Contributions received for decommissioning trusts	$ 23,000,000
Period of reviewing contributions from decommissioning trusts (in years)	3 years