Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 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	31	39
Tax positions taken during a prior year, Increases	0	1
Tax positions taken during a prior year, Decreases	(11)	(5)
Tax positions taken during a prior year, Decreases for settlements during the period	0	(83)
Balance at September 30,	452	423
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	31	39
Tax positions taken during a prior year, Increases	0	1
Tax positions taken during a prior year, Decreases	(11)	(4)
Tax positions taken during a prior year, Decreases for settlements during the period	0	(78)
Balance at September 30,	$ 351	$ 329