Other Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) (USD $) In Millions, unless otherwise specified							3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Southern California Edison	Dec. 31, 2012 Southern California Edison	Mar. 31, 2012 Southern California Edison	Dec. 31, 2011 Southern California Edison	Mar. 31, 2013 Southern California Edison Stocks	Dec. 31, 2012 Southern California Edison Stocks	Mar. 31, 2013 Southern California Edison Municipal bonds	Dec. 31, 2012 Southern California Edison Municipal bonds	Mar. 31, 2013 Southern California Edison U.S. government and agency securities	Dec. 31, 2012 Southern California Edison U.S. government and agency securities	Mar. 31, 2013 Southern California Edison Corporate bonds	Dec. 31, 2012 Southern California Edison Corporate bonds	Mar. 31, 2013 Southern California Edison Short-term investments and receivables/payables	Dec. 31, 2012 Southern California Edison Short-term investments and receivables/payables
Nuclear Decommissioning Trusts Disclosures
Longest Maturity Dates (in years)							0		2051		2043		2054		One-year
Amortized Cost			$ 2,505	$ 2,483			$ 990	$ 978	$ 509	$ 518	$ 590	$ 547	$ 327	$ 324	$ 89	$ 116
Fair Value	$ 4,246	$ 4,048	$ 4,246	$ 4,048	$ 3,853	$ 3,592	$ 2,468	$ 2,271	$ 631	$ 644	$ 646	$ 603	$ 408	$ 410	$ 93	$ 120