Other Investments (Summary of Changes in Fair Value of the Nuclear Decommissioning Trusts) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary Of Changes In The Fair Value [Roll Forward]
Balance at end of period	$ 4,799	$ 4,494
Southern California Edison
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period	4,494	4,048	3,592
Gross realized gains	197	300	73
Gross realized losses	(5)	(32)	(5)
Unrealized gains, net	75	160	276
Other-than-temporary impairments	(14)	(47)	(36)
Interest, dividends and other	118	113	113
Contributions	5	22	23
Income taxes	(62)	(66)	17
Decommissioning costs	(4)	0	0
Administrative expenses and other	(5)	(4)	(5)
Balance at end of period	$ 4,799	$ 4,494	$ 4,048