Summary of Significant Accounting Policies (Revenue Recognition) (Details) - SCE - USD ($) $ in Millions	12 Months Ended	36 Months Ended
	Dec. 31, 2018	Dec. 31, 2020
Public Utilities, General Disclosures [Line Items]
Requested revenue requirement year one	$ 5,534
Decrease in revenue requirement	106
Requested
Public Utilities, General Disclosures [Line Items]
Rate period		3 years
Requested revenue requirement year one	5,965
Requested revenue requirement year two	$ 6,468