Investments (Summary of Changes in Fair Value of the Nuclear Decommissioning Trusts) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period			$ 4,331
Balance at end of period	$ 4,376		4,376
Southern California Edison
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period	4,344	$ 4,836	4,331	$ 4,799
Gross realized gains	18	183	61	215
Gross realized losses	(1)	(10)	(5)	(15)
Unrealized gains (losses), net	32	(316)	153	(343)
Other-than-temporary impairments	(2)	(10)	(10)	(22)
Interest and dividends	28	28	88	88
Contributions	0	0	0	7
Income taxes	(5)	0	(47)	(14)
Decommissioning disbursements	(38)	(319)	(192)	(319)
Administrative expenses and other	0	(4)	(3)	(8)
Balance at end of period	$ 4,376	$ 4,388	$ 4,376	$ 4,388