Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) - Southern California Edison - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	$ 2,953	$ 3,020
Fair Value	$ 4,388	4,799
Stocks
Nuclear Decommissioning Trusts Disclosures
Maturity Dates Decommissioning Trust Investments	0
Amortized Cost	$ 386	524
Fair Value	$ 1,559	2,031
Municipal bonds
Nuclear Decommissioning Trusts Disclosures
Maturity Dates Decommissioning Trust Investments	2054
Amortized Cost	$ 726	681
Fair Value	$ 860	822
U.S. government and agency securities
Nuclear Decommissioning Trusts Disclosures
Maturity Dates Decommissioning Trust Investments	2045
Amortized Cost	$ 1,069	777
Fair Value	$ 1,141	836
Corporate bonds
Nuclear Decommissioning Trusts Disclosures
Maturity Dates Decommissioning Trust Investments	2057
Amortized Cost	$ 668	346
Fair Value	721	395
Short-term investments and receivables/payables
Fair Value Disclosures:
Repurchase agreement	$ 112
Nuclear Decommissioning Trusts Disclosures
Longest Maturity Dates	1 year
Amortized Cost	$ 104	692
Fair Value	$ 107	$ 715