Derivatives And Hedging Activities (Volumes Of Outstanding Derivative Contracts) (Details)	Dec. 31, 2014 MWh		Dec. 31, 2013 MWh
Forwards And Swaps [Member]
Derivative [Line Items]
Derivative Number of Instruments Held	5,346,787		8,089,269
Options [Member]
Derivative [Line Items]
Derivative Number of Instruments Held	164,418,002	[1],[2]	260,262,916	[1],[2]
Congestion Revenue Rights [Member]
Derivative [Line Items]
Derivative Number of Instruments Held	224,124,341	[3]	250,922,591	[3]

[1] Amounts shown are for the combined positions of the electric fuels and core gas supply portfolios.

[2] Million British Thermal Units.

[3] CRRs are financial instruments that enable the holders to manage variability in congestion costs based on demand when there is insufficient transmission capacity.