Summary of Significant Accounting Policies (Deferred Financing Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Regulatory assets	$ 5,380	$ 4,914
Edison International
Regulatory Assets [Line Items]
Amortization of deferred financing costs charged to interest expense	30	30	$ 31
Other long-term assets | Edison International
Regulatory Assets [Line Items]
Unamortized debt issuance expense	10	15
Long-term debt | Edison International
Regulatory Assets [Line Items]
Unamortized debt issuance expense	102	88
SCE
Regulatory Assets [Line Items]
Regulatory assets	5,380	4,914
Amortization of deferred financing costs charged to interest expense	26	27	$ 27
SCE | Other long-term assets
Regulatory Assets [Line Items]
Unamortized debt issuance expense	8	7
SCE | Long-term debt
Regulatory Assets [Line Items]
Unamortized debt issuance expense	93	77
SCE | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets	$ 153	$ 168