Other Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2010
Fair Value Disclosures:
Period of reviewing contributions from decommissioning trusts (in years)			3 years
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	$ 2,406,000,000		$ 2,406,000,000		$ 2,303,000,000
Fair Value	3,810,000,000	3,657,000,000	3,810,000,000	3,657,000,000	3,592,000,000	3,853,000,000	3,619,000,000	3,480,000,000
Proceeds from sale of securities	496,000,000	524,000,000	1,097,000,000	1,146,000,000
Unrealized holding gains, net of losses			1,400,000,000		1,300,000,000
Stocks
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments (in years)			0
Amortized Cost	953,000,000		953,000,000		865,000,000
Fair Value	2,090,000,000		2,090,000,000		1,899,000,000
Municipal bonds
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments (in years)			2051
Amortized Cost	583,000,000		583,000,000		625,000,000
Fair Value	714,000,000		714,000,000		756,000,000
U.S. government and agency securities
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments (in years)			2041
Amortized Cost	489,000,000		489,000,000		516,000,000
Fair Value	549,000,000		549,000,000		580,000,000
Corporate bonds
Nuclear Decommissioning Trusts Disclosures
Longest maturity dates decommissioning trust investments (in years)			2054
Amortized Cost	310,000,000		310,000,000		259,000,000
Fair Value	382,000,000		382,000,000		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	71,000,000		71,000,000		38,000,000
Fair Value	75,000,000		75,000,000		40,000,000
Southern California Edison Company
Fair Value Disclosures:
Contributions received for decommissioning trusts			$ 23,000,000