Derivative Instruments (Notional Values) (Details) (Southern California Edison, Electric Utility, Economic hedges)	Mar. 31, 2013 GWh	Dec. 31, 2012 GWh
Electricity options, swaps and forwards (GWh)
Derivatives
Notional volumes of derivative instruments	13,067	15,884
Natural gas options, swaps and forwards (Bcf)
Derivatives
Notional volumes of derivative instruments	65	100
Congestion revenue rights (GWh)
Derivatives
Notional volumes of derivative instruments	138,697	149,774
Tolling arrangements (GWh)
Derivatives
Notional volumes of derivative instruments	100,810	101,485