Investments (Summary of Changes in Fair Value of the Nuclear Decommissioning Trusts) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period			$ 4,331
Balance at end of period	$ 4,344		4,344
Southern California Edison
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period	4,290	$ 4,896	4,331	$ 4,799
Gross realized gains	22	5	75	32
Gross realized losses	(1)	(3)	(4)	(5)
Unrealized gains (losses), net	72	(71)	113	(27)
Other-than-temporary impairments	(8)	(8)	(33)	(12)
Interest and dividends	32	32	60	60
Contributions	0	0	0	7
Income taxes	(24)	(14)	(42)	(14)
Decommissioning disbursements	(38)	0	(154)	0
Administrative expenses and other	(1)	(1)	(2)	(4)
Balance at end of period	$ 4,344	$ 4,836	$ 4,344	$ 4,836