Jointly Owned Utility Facilities (Details) $ in Millions	Dec. 31, 2024 USD ($) MW	May 31, 2024 MW	Jun. 30, 2023
WE | West Riverside
Jointly owned utility facilities
Joint plant ownership percentage		27.50%
Share of capacity (MW) | MW		200
ER 1 & ER2 | We Power
Jointly owned utility facilities
Joint plant ownership percentage	83.34%
Share of capacity (MW) | MW	1,083.4
Property, plant, and equipment	$ 2,482.4
Accumulated depreciation	(548.3)
CWIP	$ 4.3
Weston Unit 4 | WPS
Jointly owned utility facilities
Joint plant ownership percentage	70.00%
Share of capacity (MW) | MW	383.4
Property, plant, and equipment	$ 600.9
Accumulated depreciation	(230.7)
CWIP	$ 1.6
Columbia Units 1 and 2 | WPS
Jointly owned utility facilities
Joint plant ownership percentage	27.50%
Share of capacity (MW) | MW	307.5
Property, plant, and equipment	$ 436.5
Accumulated depreciation	(186.9)
CWIP	$ 4.0
Forward Wind | WPS
Jointly owned utility facilities
Joint plant ownership percentage	44.60%
Share of capacity (MW) | MW	61.5
Property, plant, and equipment	$ 120.1
Accumulated depreciation	(60.0)
CWIP	$ 0.0
Two Creeks | WPS
Jointly owned utility facilities
Joint plant ownership percentage	66.70%
Share of capacity (MW) | MW	100.0
Property, plant, and equipment	$ 136.9
Accumulated depreciation	(18.6)
CWIP	$ 0.0
Badger Hollow I | WPS
Jointly owned utility facilities
Joint plant ownership percentage	66.70%
Share of capacity (MW) | MW	100.0
Property, plant, and equipment	$ 146.5
Accumulated depreciation	(14.5)
CWIP	$ 0.4
Red Barn | WPS
Jointly owned utility facilities
Joint plant ownership percentage	90.00%
Share of capacity (MW) | MW	82.4
Property, plant, and equipment	$ 150.6
Accumulated depreciation	(8.1)
CWIP	$ 0.0
West Riverside | WE
Jointly owned utility facilities
Joint plant ownership percentage	27.50%	13.70%	13.80%
Share of capacity (MW) | MW	190.5
Property, plant, and equipment	$ 217.8
Accumulated depreciation	(29.5)
CWIP	$ 3.2
Badger Hollow II | WE
Jointly owned utility facilities
Joint plant ownership percentage	66.70%
Share of capacity (MW) | MW	100.0
Property, plant, and equipment	$ 179.4
Accumulated depreciation	(6.0)
CWIP	$ 0.4
Paris Solar | WE and WPS
Jointly owned utility facilities
Joint plant ownership percentage	90.00%
Share of capacity (MW) | MW	180.0
Property, plant, and equipment	$ 357.8
Accumulated depreciation	0.0
CWIP	$ 0.5
Paris Battery | WE and WPS
Jointly owned utility facilities
Joint plant ownership percentage	90.00%
Share of capacity (MW) | MW	99
CWIP	$ 217.0
Darien solar and battery | WE and WPS
Jointly owned utility facilities
Joint plant ownership percentage	90.00%
CWIP	$ 422.2
Darien Solar Park | WE and WPS
Jointly owned utility facilities
Share of capacity (MW) | MW	225
Darien Battery | WE and WPS
Jointly owned utility facilities
Share of capacity (MW) | MW	68
Koshkonong Solar and Battery | WE and WPS
Jointly owned utility facilities
Joint plant ownership percentage	90.00%
CWIP	$ 140.3
Koshkonong Solar | WE and WPS
Jointly owned utility facilities
Share of capacity (MW) | MW	270
Koshkonong Battery | WE and WPS
Jointly owned utility facilities
Share of capacity (MW) | MW	149