ACQUISITIONS - THUNDERHEAD (Details) - Thunderhead - WECI $ in Millions	1 Months Ended
	Aug. 31, 2019 USD ($) MW	Feb. 19, 2020 USD ($)
Business Acquisition [Line Items]
Ownership interest of wind generating facility acquired	80.00%
Capacity of generation unit | MW	300
Acquisition purchase price | $	$ 338.0	$ 43.0
Additional ownership interest acquired		10.00%
Duration of offtake agreement for the sale of energy produced	12 years