Schedule I - Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Current assets
Prepaid income taxes	$ 214.9	$ 173.9
Other	121.9	223.7
Current assets	2,911.7	2,795.7
Long-term assets
Equity method investments	2,191.6	2,081.6	$ 1,981.9
Other	336.2	383.1
Noncurrent assets	44,451.5	41,144.0
Total assets	47,363.2	43,939.7	$ 41,872.1
Current liabilities
Current portion of long-term debt	1,729.0	1,264.2
Accounts payable	1,137.1	896.6
Other	859.2	933.1
Current liabilities	4,841.9	5,114.8
Long-term liabilities
Long-term debt	17,178.1	15,366.9
Other	838.1	835.3
Long-term liabilities	29,719.4	26,753.4
Equity
Total liabilities and equity	47,363.2	43,939.7
WEC Energy Group
Current assets
Prepaid income taxes	16.3	0.0
Other	0.0	0.2
Current assets	82.2	18.9
Long-term assets
Equity method investments	19,809.0	18,307.2
Other	23.2	22.9
Noncurrent assets	20,132.2	18,760.1
Total assets	20,214.4	18,779.0
Current liabilities
Short-term debt	382.7	697.0
Current portion of long-term debt	620.0	600.0
Other	69.4	73.2
Current liabilities	1,656.1	1,832.7
Long-term liabilities
Long-term debt	6,135.4	5,192.8
Other	28.0	29.3
Long-term liabilities	6,163.4	5,222.1
Equity
Common shareholders' equity	12,394.9	11,724.2
Total liabilities and equity	20,214.4	18,779.0
WEC Energy Group | Related Party
Current assets
Accounts receivable from related parties	2.7	2.7
Notes receivable from related parties	63.2	16.0
Long-term assets
Note receivable from WECI	300.0	430.0
Current liabilities
Accounts payable	3.1	2.9
Notes payable to related parties	$ 580.9	$ 459.6