Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and PBOP – net gain (loss):
Other	$ 0	$ 1	$ 0
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(53)	(56)
Pension and PBOP – net gain (loss):
Ending balance	(43)	(53)	(56)
Accumulated Defined Benefit Plans Adjustment
Pension and PBOP – net gain (loss):
Other comprehensive income (loss) before reclassifications	3	(4)
Reclassified from accumulated other comprehensive loss	7	6
Other	0	1
Change	10	3
SCE
Pension and PBOP – net gain (loss):
Other	0	1	0
SCE | Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(20)	(22)
Pension and PBOP – net gain (loss):
Ending balance	(19)	(20)	$ (22)
SCE | Accumulated Defined Benefit Plans Adjustment
Pension and PBOP – net gain (loss):
Other comprehensive income (loss) before reclassifications	(2)	(2)
Reclassified from accumulated other comprehensive loss	3	3
Other	0	1
Change	$ 1	$ 2