Revenue (Summary of Revenue) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total operating revenue	$ 3,157	$ 4,644	$ 2,987	$ 2,790	$ 2,970	$ 3,741	$ 2,812	$ 2,824	$ 13,578	$ 12,347	$ 12,657
Accrued unbilled revenue	521				488				521	488
SCE
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									12,459	11,167	12,130
Alternative revenue programs and other operating revenue3									1,087	1,139	481
Total operating revenue	3,151	$ 4,635	$ 2,980	$ 2,780	2,958	$ 3,732	2,800	$ 2,816	13,546	12,306	12,611
Receivables from contracts with customers	1,500				1,100				1,500	1,100
Accrued unbilled revenue	$ 521				$ 488				521	488
SCE | 2018 GRC | CPUC
Disaggregation of Revenue [Line Items]
Reduction in revenue							$ 289
SCE | Earning Activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									6,920	6,512	6,519
Alternative revenue programs and other operating revenue3									548	166	41
Total operating revenue									7,468	6,678	6,560
SCE | Cost- Recovery Activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									5,539	4,655	5,611
Alternative revenue programs and other operating revenue3									539	973	440
Total operating revenue									$ 6,078	$ 5,628	$ 6,051