VARIABLE INTEREST ENTITIES - WEPCO ENVIRONMENTAL TRUST (Details) - USD ($) $ in Millions	1 Months Ended
	Nov. 30, 2020	Jun. 30, 2024	Dec. 31, 2023
Assets
Other current assets (restricted cash)		$ 51.3	$ 70.1
Regulatory assets		3,393.1	3,249.8
Other long-term assets (restricted cash)		27.6	52.2
Liabilities
Current portion of long-term debt		1,157.4	1,264.2
Accounts payable		799.9	896.6
WEPCo Environmental Trust
Variable interest entities
Securitization of environmental control costs related to Pleasant Prairie power plant	$ 100.0
Assets
Other current assets (restricted cash)		0.3	0.8
Regulatory assets		82.3	85.9
Other long-term assets (restricted cash)		0.3	0.6
Liabilities
Current portion of long-term debt		9.1	9.0
Accounts payable		0.1	0.0
Other current liabilities (accrued interest)		0.1	0.1
Long-term debt		$ 80.9	$ 85.3