Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension and PBOP – net loss:
Other	$ (5)	$ 2
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(43)	(53)
Pension and PBOP – net loss:
Ending Balance	(46)	(49)
Accumulated Defined Benefit Plans Adjustment
Pension and PBOP – net loss:
Reclassified from accumulated other comprehensive loss	2	2
Other	(5)	2
Change	(3)	4
Southern California Edison
Pension and PBOP – net loss:
Other	(5)	1
Southern California Edison | Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(19)	(20)
Pension and PBOP – net loss:
Ending Balance	(22)	(18)
Southern California Edison | Accumulated Defined Benefit Plans Adjustment
Pension and PBOP – net loss:
Reclassified from accumulated other comprehensive loss	2	1
Other	(5)	1
Change	$ (3)	$ 2