ACQUISITIONS AND DISPOSITIONS - Schedule of Asset Acquisitions (Details) - Southern Power - MW	1 Months Ended		12 Months Ended
	Feb. 28, 2021	May 31, 2020	Dec. 31, 2019
Deuel Harvest
Asset Acquisition [Line Items]
Approximate Nameplate Capacity (MW)	300
Deuel Harvest | Maximum
Asset Acquisition [Line Items]
PPA Contract Period	25 years
Deuel Harvest | Minimum
Asset Acquisition [Line Items]
PPA Contract Period	15 years
Beech Ridge II
Asset Acquisition [Line Items]
Approximate Nameplate Capacity (MW)		56
PPA Contract Period		12 years
DSGP
Asset Acquisition [Line Items]
Approximate Nameplate Capacity (MW)			28
PPA Contract Period			15 years
Noncontrolling interest, approximate nameplate capacity (in MW)			10
Approximate nameplate capacity, repowered amount (in MW)			18
Deuel Harvest | Deuel Harvest
Asset Acquisition [Line Items]
Ownership Percentage	100.00%
Beech Ridge II | Beech Ridge II
Asset Acquisition [Line Items]
Ownership Percentage		100.00%
DSGP | DSGP
Asset Acquisition [Line Items]
Ownership Percentage			100.00%