DERIVATIVES (Volumes of Outstanding Derivative Contracts) (Details)	Sep. 30, 2023 MWh MMBTU	Dec. 31, 2022 MWh MMBTU
Forwards, Futures and Swaps | Natural Gas (MMBtus)
Derivative [Line Items]
Contract Volume	243,455,325	171,212,813
Forwards, Futures and Swaps | Electricity (MWh)
Derivative [Line Items]
Contract Volume | MWh	8,464,522	10,814,728
Options | Natural Gas (MMBtus)
Derivative [Line Items]
Contract Volume	75,115,000	27,785,000
Options | Electricity (MWh)
Derivative [Line Items]
Contract Volume	0	215,600
Congestion revenue rights | Electricity (MWh)
Derivative [Line Items]
Contract Volume | MWh	179,224,328	205,743,505