Summary of Significant Accounting Policies (Allowance) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for long-term uncollectible accounts	$ 99		$ 116
SCE
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	309	$ 188
Included in operation and maintenance expenses in earning activities	20	10
Included in operation and maintenance expenses in cost-recovery activities	38	32
Deferred to regulatory memorandum accounts	3	2
Less: write-offs, net of recoveries	17	6
Ending balance	353	226
Allowance for long-term uncollectible accounts	99		$ 116
SCE | Customers
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	293	175
Included in operation and maintenance expenses in earning activities	13	6
Included in operation and maintenance expenses in cost-recovery activities	38	32
Deferred to regulatory memorandum accounts	3	2
Less: write-offs, net of recoveries	10	5
Ending balance	337	210
SCE | All others
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	16	13
Included in operation and maintenance expenses in earning activities	7	4
Less: write-offs, net of recoveries	7	1
Ending balance	$ 16	$ 16