Other Investments (Summary of Changes in Fair Value of the Nuclear Decommissioning Trusts) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period			$ 4,799
Balance at end of period	4,896		4,799
Southern California Edison
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period	4,799	4,494
Gross realized gains	27	10
Gross realized losses	(2)	0
Unrealized gains, net	44	62
Other-than-temporary impairments	(4)	(3)
Interest and dividends	28	28
Contributions	7	5
Income taxes	0	(7)
Administrative expenses and other	(3)	(2)
Balance at end of period	$ 4,896	$ 4,587