DERIVATIVES (Volumes of Outstanding Derivative Contracts) (Details)	Dec. 31, 2021 MMBTU MWh	Dec. 31, 2020 MMBTU MWh
Forwards, Futures and Swaps | Natural Gas (MMBtus)
Derivative [Line Items]
Contract Volume	173,361,635	146,642,863
Forwards, Futures and Swaps | Electricity (Megawatt-hours)
Derivative [Line Items]
Contract Volume | MWh	10,283,639	9,435,830
Options | Natural Gas (MMBtus)
Derivative [Line Items]
Contract Volume	14,420,000	14,140,000
Options | Electricity (Megawatt-hours)
Derivative [Line Items]
Contract Volume	288,000	0
Congestion revenue rights | Electricity (Megawatt-hours)
Derivative [Line Items]
Contract Volume | MWh	239,857,610	266,091,470