Revenue (Summary of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total operating revenue	$ 2,815	$ 2,965	$ 5,379	$ 5,428
Southern California Edison
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,680		5,408
Alternative revenue programs and other operating revenue	123		(51)
Total operating revenue	2,803	2,953	5,357	5,409
Southern California Edison | Earning Activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,534		3,070
Alternative revenue programs and other operating revenue	1		(22)
Total operating revenue	1,535	1,584	3,048	3,136
Southern California Edison | Cost- Recovery Activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,146		2,338
Alternative revenue programs and other operating revenue	122		(29)
Total operating revenue	$ 1,268	$ 1,369	$ 2,309	$ 2,273