Summary of Significant Accounting Policies (Impairment of Long-Lived Assets) (Details) - USD ($) $ in Millions	12 Months Ended			24 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2014
Jointly Owned Utility Plant Interests [Line Items]
Impairment and other charges	$ 21	$ 5	$ 157
SCE
Jointly Owned Utility Plant Interests [Line Items]
Impairment and other charges	$ 0	$ 0	163
San Onofre | SCE
Jointly Owned Utility Plant Interests [Line Items]
Impairment and other charges			163	$ 738
Impairment and other charges, net of tax			$ 72	$ 437