Summary of Significant Accounting Policies (Revenue Recognition) (Details) - SCE - USD ($) $ in Millions	1 Months Ended			3 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jul. 31, 2019	Mar. 31, 2021
Public Utilities, General Disclosures [Line Items]
Requested increase (decrease) in revenue requirement	$ 214		$ 505
Approved regulatory increase (decrease) in revenue		$ 505
2021 General Rate Case
Public Utilities, General Disclosures [Line Items]
Requested test year revenue requirement				$ 7,600
Requested increase (decrease) in revenue requirement				$ 1,300