Income Taxes (Net Operating Loss and Tax Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring 2021 to 2038	$ 1,073
Loss Carryforwards, No expiration date	0
Loss Carryforwards	1,073
Credit Carryforward, Expiring 2021 to 2038	469
Credit Carryforward, No expiration date	11
Credit Carryforwards	480
SCE
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring 2021 to 2038	203
Loss Carryforwards, No expiration date	0
Loss Carryforwards	203
Credit Carryforward, Expiring 2021 to 2038	26
Credit Carryforward, No expiration date	22
Credit Carryforwards	$ 48