Summary of Significant Accounting Policies (Deferred Financing) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Regulatory Assets [Line Items]
Regulatory assets	$ 7,660	$ 7,120
Unamortized debt issuance expense	153	131
Amortization of deferred financing costs charged to interest expense	34	32	$ 30
SCE
Regulatory Assets [Line Items]
Regulatory assets	7,660	7,120
Unamortized debt issuance expense	143	117
Amortization of deferred financing costs charged to interest expense	29	27	$ 26
SCE | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets	$ 121	$ 133