Investments (Trust Info) (Details) - SCE - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Investment Holdings [Line Items]
Unrealized holding gains, net of losses	$ 1,900	$ 2,100
Deferred income taxes related to unrealized gains	511	515
Nuclear decommissioning trusts, net of deferred tax	$ 4,300	$ 4,300