Summary of Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			27 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Mar. 31, 2015
Summary of Significant Accounting Policies [Line Items]
Impairment and other charges	$ 0	$ 231
Southern California Edison
Summary of Significant Accounting Policies [Line Items]
Impairment and other charges	0	231
Southern California Edison | Electric Utility
Summary of Significant Accounting Policies [Line Items]
Supply of electricity, area covered (square mile)	50,000
San Onofre | Southern California Edison
Summary of Significant Accounting Policies [Line Items]
Impairment and other charges		231	163	738
Asset impairment net of tax		$ 96	$ 72	$ 437