Other Investments (Summary of Changes in Fair Value of the Nuclear Decommissioning Trusts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period	$ 4,799
Balance at end of period	4,331	$ 4,799
Southern California Edison
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period	4,799	4,494	$ 4,048
Gross realized gains	326	197	300
Gross realized losses	(26)	(5)	(32)
Unrealized (losses) gains	(364)	75	160
Other-than-temporary impairments	(29)	(14)	(47)
Interest, dividends and other	115	118	113
Contributions	54	5	22
Income taxes	(64)	(62)	(66)
Decommissioning disbursements	(471)	(4)	0
Administrative expenses and other	(9)	(5)	(4)
Balance at end of period	$ 4,331	$ 4,799	$ 4,494