Summary of Significant Accounting Policies (Uncollectible Allowance) (Details) - SCE - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 226	$ 60	$ 188	$ 49
Included in operation and maintenance expenses	15	17	25	35
Deferred to regulatory assets	32	21	66	21
Less: write-offs, net of recoveries	3	8	9	15
Ending balance	270	90	270	90
Customers
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	210	47	175	35
Included in operation and maintenance expenses	12	12	18	28
Deferred to regulatory assets	32	21	66	21
Less: write-offs, net of recoveries		5	5	9
Ending balance	254	75	254	75
All others
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	16	13	13	14
Included in operation and maintenance expenses	3	5	7	7
Less: write-offs, net of recoveries	3	3	4	6
Ending balance	$ 16	$ 15	$ 16	$ 15