Income Taxes (Net Operating Loss and Tax Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2019 USD ($)
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring 2021 to 2038	$ 1,024
Loss Carryforwards, Expiring between 2021 to 2024	29
Loss Carryforwards, No expiration date	182
Loss Carryforwards	1,235
Credit Carryforward, Expiring 2021 to 2038	482
Credit Carryforwards, Expiring between 2021 to 2024	0
Credit Carryforward, No expiration date	10
Credit Carryforwards	492
SCE
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring 2021 to 2038	229
Loss Carryforwards, Expiring between 2021 to 2024	24
Loss Carryforwards, No expiration date	100
Loss Carryforwards	353
Credit Carryforward, Expiring 2021 to 2038	30
Credit Carryforwards, Expiring between 2021 to 2024	0
Credit Carryforward, No expiration date	0
Credit Carryforwards	$ 30