Schedule I - Income Statements (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended								12 Months Ended
	Dec. 31, 2020	Oct. 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income statements
Equity in earnings of subsidiaries											$ 175.8	$ 127.6	$ 136.7
Other income, net											79.5	102.2	70.3
Interest expense											493.7	501.5	445.1
Loss on debt extinguishment	$ (10.5)	$ (27.9)									(38.4)	0.0	0.0
Income before income taxes											1,429.3	1,259.7	1,230.3
Income tax benefit											(227.9)	(125.0)	(169.8)
Net income attributed to common shareholders			$ 239.0	$ 266.8	$ 241.6	$ 452.5	$ 243.9	$ 234.3	$ 235.7	$ 420.1	1,199.9	1,134.0	1,059.3
WEC Energy Group
Income statements
Operating expenses											5.3	4.7	5.0
Equity in earnings of subsidiaries											1,283.8	1,210.5	1,108.3
Other income, net											1.3	6.3	6.8
Interest expense											96.9	122.3	104.1
Loss on debt extinguishment											(38.4)	0.0	0.0
Income before income taxes											1,144.5	1,089.8	1,006.0
Income tax benefit											55.4	44.2	53.3
Net income attributed to common shareholders											$ 1,199.9	$ 1,134.0	$ 1,059.3