Income Taxes (Operating Loss and Tax Carryforward) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring 2017 to 2035	$ 1,095
Loss Carryforwards, No expiration date	0
Loss Carryforwards	1,095
Credit Carryforward, Expiring 2017 to 2035	430
Credit Carryforward, No expiration date	69
Credit Carryforwards	499
Unrecognized tax benefits	471	$ 529	$ 576	$ 815
SCE
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring 2017 to 2035	20
Loss Carryforwards, No expiration date	0
Loss Carryforwards	20
Credit Carryforward, Expiring 2017 to 2035	25
Credit Carryforward, No expiration date	37
Credit Carryforwards	62
Unrecognized tax benefits	371	$ 353	$ 441	$ 532
Loss And Credit Carryforwards
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits	176
Loss And Credit Carryforwards | SCE
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits	$ 82