Summary of Significant Accounting Policies (Deferred Financing Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Regulatory Assets [Line Items]
Regulatory assets	$ 6,088	$ 5,380
Edison International
Regulatory Assets [Line Items]
Amortization of deferred financing costs charged to interest expense	30	30	$ 30
Long-term debt | Edison International
Regulatory Assets [Line Items]
Unamortized debt issuance expense	121	102
SCE
Regulatory Assets [Line Items]
Regulatory assets	6,088	5,380
Amortization of deferred financing costs charged to interest expense	26	26	$ 27
SCE | Long-term debt
Regulatory Assets [Line Items]
Unamortized debt issuance expense	106	93
SCE | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets	$ 142	$ 153