ACQUISITIONS AND DISPOSITIONS - Schedule of Acquisition (Details) - SOUTHERN POWER CO - MW	1 Months Ended
	May 31, 2020	Mar. 31, 2020
Business Acquisition [Line Items]
Approximate nameplate capacity (in MWs)		300
Beech Ridge II
Business Acquisition [Line Items]
Approximate nameplate capacity (in MWs)	56
PPA Contract Period	12 years
Beech Ridge II | Beech Ridge II
Business Acquisition [Line Items]
Ownership percentage by parent	100.00%