Other Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Fair Value Disclosures:
Period of reviewing contributions from decommissioning trusts (in years)			3 years
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	$ 2,437,000,000		$ 2,437,000,000			$ 2,303,000,000
Fair Value	3,997,000,000	3,393,000,000	3,997,000,000	3,393,000,000	3,810,000,000	3,592,000,000	3,657,000,000	3,480,000,000
Proceeds from sale of securities	428,000,000	962,000,000	1,525,000,000	2,108,000,000
Unrealized holding gains, net of losses	1,600,000,000		1,600,000,000			1,300,000,000
Stocks
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments (in years)			0
Amortized Cost	957,000,000		957,000,000			865,000,000
Fair Value	2,227,000,000		2,227,000,000			1,899,000,000
Municipal bonds
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments (in years)			2054
Amortized Cost	520,000,000		520,000,000			625,000,000
Fair Value	654,000,000		654,000,000			756,000,000
U.S. government and agency securities
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments (in years)			2042
Amortized Cost	526,000,000		526,000,000			516,000,000
Fair Value	589,000,000		589,000,000			580,000,000
Corporate bonds
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments (in years)			2054
Amortized Cost	287,000,000		287,000,000			259,000,000
Fair Value	374,000,000		374,000,000			317,000,000
Short-term investments and receivables/payables
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments (in years)			One-year
Amortized Cost	147,000,000		147,000,000			38,000,000
Fair Value	153,000,000		153,000,000			40,000,000
Southern California Edison
Fair Value Disclosures:
Contributions received for decommissioning trusts			$ 23,000,000