Investments (Nuclear Decommissioning Trusts) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Unrealized holding gains, net of losses	$ 1,400	$ 1,600
Other-than-temporary impairments	170	$ 143
Deferred income taxes related to unrealized gains	323
Nuclear decommissioning trusts	$ 3,800