Other Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Nuclear Decommissioning Trusts Disclosures
Fair Value	$ 4,799	$ 4,494
Southern California Edison
Nuclear Decommissioning Trusts Disclosures
Amortized Cost	3,020	2,770
Fair Value	4,799	4,494	4,048	3,592
Southern California Edison | Stocks
Nuclear Decommissioning Trusts Disclosures
Longest Maturity Dates (in years)	0
Amortized Cost	524	656
Fair Value	2,031	2,208
Southern California Edison | Municipal bonds
Nuclear Decommissioning Trusts Disclosures
Longest Maturity Dates (in years)	2054
Amortized Cost	681	675
Fair Value	822	756
Southern California Edison | U.S. government and agency securities
Nuclear Decommissioning Trusts Disclosures
Longest Maturity Dates (in years)	2045
Amortized Cost	777	902
Fair Value	836	947
Southern California Edison | Corporate bonds
Nuclear Decommissioning Trusts Disclosures
Longest Maturity Dates (in years)	2057
Amortized Cost	346	208
Fair Value	395	241
Southern California Edison | Short-term investments and receivables/payables
Nuclear Decommissioning Trusts Disclosures
Longest Maturity Dates (in years)	One-year
Amortized Cost	692	329
Fair Value	$ 715	$ 342