Income Taxes (Net Operating Loss and Tax Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2020 USD ($)
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring in one year	$ 4
Loss Carryforwards, Expiring between 2022 to 2045	31
Loss Carryforwards, Expiring between 2029 to 2042	1,192
Loss Carryforwards, No expiration date	509
Loss Carryforwards	1,736
Tax Credit Carryforward, Expiring in one year	0
Tax Credit Carryforward, Expiring In Years Two Through Five	0
Credit Carryforward, Expiring 2029 to 2042	515
Credit Carryforward, No expiration date	10
Credit Carryforwards	525
SCE
Tax Credit Carryforward [Line Items]
Loss Carryforwards, Expiring in one year	4
Loss Carryforwards, Expiring between 2022 to 2045	26
Loss Carryforwards, Expiring between 2029 to 2042	380
Loss Carryforwards, No expiration date	413
Loss Carryforwards	823
Tax Credit Carryforward, Expiring in one year	0
Tax Credit Carryforward, Expiring In Years Two Through Five	0
Credit Carryforward, Expiring 2029 to 2042	50
Credit Carryforward, No expiration date	0
Credit Carryforwards	$ 50