Revenue (Summary of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Total operating revenue	$ 2,960	$ 2,790
SCE
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,899	2,342
Alternative revenue programs and other operating revenue	54	438
Total operating revenue	2,953	2,780
Receivables from contracts with customers	1,600		$ 1,500
Accrued unbilled revenues	673		$ 521
SCE | Earning Activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,704	1,624
Alternative revenue programs and other operating revenue	63	117
Total operating revenue	1,767	1,741
SCE | Cost- Recovery Activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,195	718
Alternative revenue programs and other operating revenue	(9)	321
Total operating revenue	$ 1,186	$ 1,039