JOINTLY OWNED UTILITY FACILITIES (Details) $ in Millions	Dec. 31, 2021 USD ($) MW
Weston Unit 4
Jointly owned utility facilities
Ownership (as a percent)	70.00%
Share of capacity (MW) | MW	387.3
Property, plant, and equipment	$ 598.4
Accumulated depreciation	(224.3)
Construction work in progress	$ 3.8
Columbia Energy Center Units 1 and 2
Jointly owned utility facilities
Ownership (as a percent)	27.50%
Share of capacity (MW) | MW	311.1
Property, plant, and equipment	$ 425.4
Accumulated depreciation	(161.9)
Construction work in progress	$ 3.9
Forward Wind Energy Center
Jointly owned utility facilities
Ownership (as a percent)	44.60%
Share of capacity (MW) | MW	61.5
Property, plant, and equipment	$ 122.5
Accumulated depreciation	(53.3)
Construction work in progress	$ 0.0
Two Creeks
Jointly owned utility facilities
Ownership (as a percent)	66.70%
Share of capacity (MW) | MW	100.0
Property, plant, and equipment	$ 136.7
Accumulated depreciation	(5.3)
Construction work in progress	$ 0.0
Badger Hollow I
Jointly owned utility facilities
Ownership (as a percent)	66.70%
Share of capacity (MW) | MW	100.0
Property, plant, and equipment	$ 134.5
Accumulated depreciation	(0.4)
Construction work in progress	$ 0.1
Red Barn Wind Park
Jointly owned utility facilities
Ownership (as a percent)	90.00%
Share of capacity (MW) | MW	82