Schedule I - Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net income attributed to common shareholders	$ 1,331.7	$ 1,408.1	$ 1,300.3
Reconciliation to cash provided by operating activities
Equity income in subsidiaries, net of distributions	(33.0)	(74.3)	(25.1)
Deferred income taxes, net	229.9	278.5	111.0
Loss on debt extinguishment	0.0	0.0	36.3
Change in -
Other current assets	18.9	(27.7)	17.6
Other current liabilities	47.5	126.9	(17.2)
Other, net	(156.5)	(169.5)	(92.5)
Net cash provided by operating activities	3,018.4	2,060.7	2,032.7
Investing activities
Capital contributions to subsidiaries	(63.7)	(45.5)	0.0
Other, net	(12.6)	(11.4)	27.3
Net cash used in investing activities	(3,558.2)	(2,642.4)	(2,311.8)
Financing activities
Exercise of stock options	6.3	33.6	15.7
Purchase of common stock	(16.6)	(69.2)	(33.1)
Dividends paid on common stock	(984.2)	(917.9)	(854.8)
Issuance of long-term debt	2,170.0	1,999.3	2,383.8
Retirement of long-term debt	(1,005.4)	(92.1)	(1,260.4)
Repayment of short-term loan	(0.8)	0.0	(340.0)
Change in commercial paper	373.7	(252.6)	459.2
Payments for debt extinguishment and issuance costs	(14.2)	(15.6)	(67.2)
Other, net	(6.0)	(9.1)	(9.2)
Net cash provided by financing activities	522.8	676.4	294.0
Net change in cash, cash equivalents, and restricted cash	(17.0)	94.7	14.9
Cash, cash equivalents, and restricted cash at beginning of year	182.2	87.5	72.6
Cash, cash equivalents, and restricted cash at end of year	165.2	182.2	87.5
WEC Energy Group
Operating activities
Net income attributed to common shareholders	1,331.7	1,408.1	1,300.3
Reconciliation to cash provided by operating activities
Equity income in subsidiaries, net of distributions	(566.8)	(437.4)	(571.3)
Deferred income taxes, net	(3.8)	11.6	(1.9)
Loss on debt extinguishment	0.0	0.0	23.1
Change in -
Accounts receivable from related parties	(2.0)	(0.1)	0.1
Prepaid income taxes	35.4	21.1	(2.1)
Other current assets	(0.1)	0.0	0.0
Accounts payable to related parties	0.9	(3.5)	(26.2)
Accrued interest	42.1	15.4	0.4
Other current liabilities	(0.7)	(5.1)	8.2
Other, net	14.4	5.8	(2.5)
Net cash provided by operating activities	851.1	1,015.9	728.1
Investing activities
Capital contributions to subsidiaries	(1,807.4)	(1,099.7)	(734.0)
Return of capital from subsidiaries	175.2	372.9	196.1
Short-term notes receivable from related parties, net	14.9	(1.9)	81.8
Other, net	0.0	(2.0)	(1.1)
Net cash used in investing activities	(1,617.3)	(730.7)	(457.2)
Financing activities
Exercise of stock options	6.3	33.6	15.7
Purchase of common stock	(16.6)	(69.2)	(33.1)
Dividends paid on common stock	(984.2)	(917.9)	(854.8)
Issuance of long-term debt	2,050.0	900.0	1,100.0
Retirement of long-term debt	(700.0)	0.0	(300.0)
Repayment of short-term loan	0.0	0.0	(340.0)
Change in commercial paper	297.3	(336.4)	255.7
Short-term notes payable to related parties, net	127.1	112.1	(82.6)
Payments for debt extinguishment and issuance costs	(13.3)	(6.7)	(33.9)
Other, net	(0.4)	(1.2)	(1.4)
Net cash provided by financing activities	766.2	(285.7)	(274.4)
Net change in cash, cash equivalents, and restricted cash	0.0	(0.5)	(3.5)
Cash, cash equivalents, and restricted cash at beginning of year	0.0	0.5	4.0
Cash, cash equivalents, and restricted cash at end of year	$ 0.0	$ 0.0	$ 0.5