Income Taxes (Interest and Penalties Related to Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Line Items]
Accrued interest and penalties	$ 128	$ 122
Net after-tax interest and penalties tax benefit	6	9	$ 41
SCE
Income Tax Disclosure [Line Items]
Accrued interest and penalties	41	40
Net after-tax interest and penalties tax benefit	$ 2	$ 14	$ 16