Investments (Gains and Losses on Equity Investments) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investment Holdings [Line Items]
Gross realized gains	$ 134	$ 244	$ 92
Gross realized losses	(27)	(23)	(19)
Net unrealized (losses) gains for equity securities	$ (233)	$ 142	$ 75