Investments (Gains and Losses on Equity Investments) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Gross realized gains	$ 87	$ 134	$ 244
Gross realized losses	(2)	(27)	(23)
Net unrealized gains (losses) for equity securities	$ 343	$ (233)	$ 142