Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1, 2017	$ 471
Tax positions taken during the current year, Increases	10
Tax positions taken during a prior year, Increases	2
Tax positions taken during a prior year, Decreases	(10)
Tax positions taken during a prior year, Decreases for settlements during the period	(82)
Balance at March 31, 2017	391
Southern California Edison
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1, 2017	371
Tax positions taken during the current year, Increases	10
Tax positions taken during a prior year, Increases	2
Tax positions taken during a prior year, Decreases	(10)
Tax positions taken during a prior year, Decreases for settlements during the period	(78)
Balance at March 31, 2017	$ 295