Investments (Nuclear Decommissioning Trusts) (Details) - Southern California Edison - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Investment Holdings [Line Items]
Unrealized holding gains, net of losses	$ 1,600	$ 1,400
Other-than-temporary impairments	162	170
Deferred income taxes related to unrealized gains	366	323
Nuclear decommissioning trusts	$ 3,900	$ 3,800