Derivative Instruments (Notional Values) (Details) - Southern California Edison - Electric Utility - Economic Hedges GWh in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017 GWh Bcfe	Dec. 31, 2016 GWh Bcfe
Electricity options, swaps and forwards (GWh)
Derivative [Line Items]
Notional volumes of derivative instruments	1,812	1,816
Natural gas options, swaps and forwards (Bcf)
Derivative [Line Items]
Notional volumes of derivative instruments | Bcfe	123	36
Congestion revenue rights (GWh)
Derivative [Line Items]
Notional volumes of derivative instruments	79,224	93,319
Tolling arrangements (GWh)
Derivative [Line Items]
Notional volumes of derivative instruments	58,153	61,093