Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 15,949	$ 15,496
Pension and PBOP - net loss:
Other comprehensive income, net of tax	2	2
Ending balance	17,223	15,544
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(69)	(69)
Pension and PBOP - net loss:
Ending balance	(67)	(67)
Accumulated Defined Benefit Plans Adjustment
Pension and PBOP - net loss:
Reclassified from accumulated other comprehensive loss	2	2
Other comprehensive income, net of tax	2	2
SCE
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	18,650	17,827
Pension and PBOP - net loss:
Other comprehensive income, net of tax	2	2
Ending balance	19,522	18,046
SCE | Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(41)	(39)
Pension and PBOP - net loss:
Ending balance	(39)	(37)
SCE | Accumulated Defined Benefit Plans Adjustment
Pension and PBOP - net loss:
Reclassified from accumulated other comprehensive loss	2	2
Other comprehensive income, net of tax	$ 2	$ 2