Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits
Balance at January 1,	$ 338	$ 432	$ 471
Tax positions taken during the current year, Increases	46	41	51
Tax positions taken during a prior year, Increases	6	0	0
Tax positions taken during a prior year, Decreases	(20)	(108)	(7)
Tax positions taken during a prior year, Decreases for settlements during the period	0	(27)	(83)
Balance at December 31,	370	338	432
SCE
Reconciliation of Unrecognized Tax Benefits
Balance at January 1,	249	331	371
Tax positions taken during the current year, Increases	47	42	51
Tax positions taken during a prior year, Increases	6	0	0
Tax positions taken during a prior year, Decreases	(20)	(121)	(13)
Tax positions taken during a prior year, Decreases for settlements during the period	0	(3)	(78)
Balance at December 31,	$ 282	$ 249	$ 331