Investments (Summary of Changes in Fair Value of the Nuclear Decommissioning Trust) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period	$ 4,331
Balance at end of period	4,242	$ 4,331
SCE
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period	4,331	4,799	$ 4,494
Gross realized gains	92	326	197
Gross realized losses	(19)	(26)	(5)
Unrealized gains (losses)	44	(364)	75
Other-than-temporary impairments	(36)	(29)	(14)
Interest, dividends and other	116	115	118
Contributions	0	54	5
Income taxes	(58)	(64)	(62)
Decommissioning disbursements	(224)	(471)	(4)
Administrative expenses and other	(4)	(9)	(5)
Balance at end of period	$ 4,242	$ 4,331	$ 4,799