Income Taxes (Components of Net Accumulated Deferred Income Tax Liability) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
Deferred tax assets:
Property	$ 590		$ 478
Wildfire reserve	1,134		847
Nuclear decommissioning trust assets in excess of nuclear ARO liability	515		449
Loss and credit carryforwards	1,991		1,515
Regulatory asset	841		739
Pension and postretirement benefits other than pensions, net	163		170
Other	513		408
Sub-total	5,747		4,606
Less: valuation allowance	35		35
Total	5,712		4,571
Deferred tax liabilities:
Property	8,879		8,244
Regulatory liability	1,111		570
Nuclear decommissioning trust assets	515		449
Other	514		320
Total	11,019		9,583
Accumulated deferred income tax liability, net	5,307		5,012
Unrecognized tax benefits	679	$ 338	370	$ 432
Recorded valuation allowance	31
Capital loss from sale of SoCore Energy
Deferred tax liabilities:
Recorded valuation allowance	4	4
Loss and Credit Carryforwards
Deferred tax liabilities:
Unrecognized tax benefits	270
SCE
Deferred tax assets:
Property	540		435
Wildfire reserve	1,134		847
Nuclear decommissioning trust assets in excess of nuclear ARO liability	515		449
Loss and credit carryforwards	683		253
Regulatory asset	841		739
Pension and postretirement benefits other than pensions, net	35		40
Other	527		416
Sub-total	4,275		3,179
Less: valuation allowance	0		0
Total	4,275		3,179
Deferred tax liabilities:
Property	8,871		8,234
Regulatory liability	1,111		570
Nuclear decommissioning trust assets	515		449
Other	499		310
Total	10,996		9,563
Accumulated deferred income tax liability, net	6,721		6,384
Unrecognized tax benefits	320	$ 249	$ 282	$ 331
SCE | Loss and Credit Carryforwards
Deferred tax liabilities:
Unrecognized tax benefits	$ 190