Investments (Nuclear Decommissioning Trusts) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investment Holdings [Line Items]
Unrealized holding gains, net of losses	$ 1,800	$ 1,400
Other-than-temporary impairments	160	$ 170
Deferred income taxes related to unrealized gains	449
Nuclear decommissioning trusts	$ 4,100