Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 17,313	$ 16,446	$ 15,949	$ 15,496
Pension and PBOP - net loss:
Other comprehensive income, net of tax	2	2	6	6
Ending balance	16,742	15,649	16,742	15,649
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(65)	(65)	(69)	(69)
Pension and PBOP - net loss:
Ending balance	(63)	(63)	(63)	(63)
Accumulated Defined Benefit Plans Adjustment
Pension and PBOP - net loss:
Reclassified from accumulated other comprehensive loss	2	2	6	6
Other comprehensive income, net of tax	2	2	6	6
SCE
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	19,887	18,781	18,650	17,827
Pension and PBOP - net loss:
Other comprehensive income, net of tax	2	1	5	4
Ending balance	19,368	18,179	19,368	18,179
SCE | Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(38)	(36)	(41)	(39)
Pension and PBOP - net loss:
Ending balance	(36)	(35)	(36)	(35)
SCE | Accumulated Defined Benefit Plans Adjustment
Pension and PBOP - net loss:
Reclassified from accumulated other comprehensive loss	2	1	5	4
Other comprehensive income, net of tax	$ 2	$ 1	$ 5	$ 4