Revenue (Summary of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Total operating revenue	$ 4,269	$ 3,672	$ 9,648	$ 9,100
Southern California Edison
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,106		9,514
Alternative revenue programs and other operating revenue	154		103
Total operating revenue	4,260	3,652	9,617	9,061
Southern California Edison | Earning Activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,851		4,921
Alternative revenue programs and other operating revenue	(74)		(96)
Total operating revenue	1,777	1,677	4,825	4,813
Southern California Edison | Cost- Recovery Activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,255		4,593
Alternative revenue programs and other operating revenue	228		199
Total operating revenue	$ 2,483	$ 1,975	$ 4,792	$ 4,248