Schedule I - Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current assets
Prepaid income taxes	$ 173.9	$ 201.8
Other	223.7	261.7
Current assets	2,795.7	3,187.7
Long-term assets
Other	383.1	427.3
Assets, Noncurrent	41,144.0	38,684.4
Total assets	43,939.7	41,872.1	$ 38,988.5
Current liabilities
Current portion of long-term debt	1,264.2	808.5
Accounts payable	896.6	1,198.1
Other	933.1	884.6
Current liabilities	5,114.8	4,611.0
Long-term liabilities
Long-term debt	15,366.9	14,655.7
Other	659.3	660.6
Long-term liabilities	26,753.4	25,644.5
Equity
Total liabilities and equity	43,939.7	41,872.1
WEC Energy Group
Current assets
Prepaid income taxes	0.0	35.4
Other	0.2	0.1
Current assets	18.9	67.1
Long-term assets
Investments in subsidiaries	18,307.2	16,533.4
Other	22.9	24.2
Assets, Noncurrent	18,760.1	16,557.6
Total assets	18,779.0	16,624.7
Current liabilities
Short-term debt	697.0	399.7
Current portion of long-term debt	600.0	700.0
Other	73.2	31.8
Current liabilities	1,832.7	1,466.0
Long-term liabilities
Long-term debt	5,192.8	3,747.2
Other	29.3	34.6
Long-term liabilities	5,222.1	3,781.8
Equity
Common shareholders' equity	11,724.2	11,376.9
Total liabilities and equity	18,779.0	16,624.7
WEC Energy Group | Related Party
Current assets
Accounts receivable from related parties	2.7	0.7
Notes receivable from related parties	16.0	30.9
Long-term assets
Note receivable from WECI	430.0	0.0
Current liabilities
Accounts payable	2.9	2.0
Notes payable to related parties	$ 459.6	$ 332.5