Derivative Instruments - Cash Flow Hedges (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Nov. 15, 2021 USD ($) number_of_interest_rate_swaps
Derivative instruments
Total interest expense line item on the income statements	$ 515.1	$ 471.1	$ 493.7
WEC Energy Group
Derivative instruments
Total interest expense line item on the income statements	109.6	70.2	96.9
WEC Energy Group | WEC Energy Group 2007 junior notes due 2067
Derivative instruments
Long-term debt outstanding	500.0	500.0		$ 500.0
Interest rate swaps | WEC Energy Group
Derivative instruments
Number of interest rate swaps | number_of_interest_rate_swaps				2
Interest rate swap notional value				$ 250.0
Interest rate swap fixed interest rate				4.9765%
Derivative gain (loss) recognized in other comprehensive income / loss	0.0	0.8	(5.9)
Net derivative gain (loss) reclassified from accumulated other comprehensive loss to interest expense	0.4	$ (1.3)	$ (2.1)
Reclassification to interest expense within next twelve months	$ 0.4