Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1,	$ 432	$ 471
Tax positions taken during the current year, Increases	21	20
Tax positions taken during a prior year, Increases	0	3
Tax positions taken during a prior year, Decreases	(7)	0
Tax positions taken during a prior year, Decreases for settlements during the period	0	(83)
Balance at June 30,	446	411
Southern California Edison
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1,	331	371
Tax positions taken during the current year, Increases	21	20
Tax positions taken during a prior year, Increases	0	3
Tax positions taken during a prior year, Decreases	(7)	0
Tax positions taken during a prior year, Decreases for settlements during the period	0	(78)
Balance at June 30,	$ 345	$ 316