Schedule I - Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net income attributed to common shareholders	$ 1,408.1	$ 1,300.3	$ 1,199.9
Reconciliation to cash provided by operating activities
Equity income in subsidiaries, net of distributions	(74.3)	(25.1)	(29.1)
Deferred income taxes, net	278.5	111.0	182.2
Loss on debt extinguishment	0.0	36.3	38.4
Change in -
Other current liabilities	126.9	(17.2)	(41.2)
Other, net	(169.5)	(92.5)	(29.3)
Net cash provided by operating activities	2,060.7	2,032.7	2,196.0
Investing activities
Capital contributions to subsidiaries	(45.5)	0.0	(21.2)
Other, net	7.8	27.3	(1.8)
Net cash used in investing activities	(2,642.4)	(2,311.8)	(2,806.8)
Financing activities
Exercise of stock options	33.6	15.7	43.8
Purchase of common stock	(69.2)	(33.1)	(99.2)
Dividends paid on common stock	(917.9)	(854.8)	(798.0)
Issuance of long-term debt	1,999.3	2,383.8	2,373.6
Retirement of long-term debt	(92.1)	(1,260.4)	(1,767.0)
Issuance of short-term loan	2.7	0.9	340.0
Repayment of short-term loan	0.0	(340.0)	0.0
Change in commercial paper	(252.6)	459.2	606.1
Payments for debt extinguishment and issuance costs	(15.6)	(67.2)	(55.8)
Other, net	(11.8)	(10.1)	(11.4)
Net cash used in financing activities	(676.4)	(294.0)	(601.1)
Net change in cash, cash equivalents, and restricted cash	94.7	14.9	(9.7)
Cash, cash equivalents, and restricted cash at beginning of year	87.5	72.6	82.3
Cash, cash equivalents, and restricted cash at end of year	182.2	87.5	72.6
WEC Energy Group
Operating activities
Net income attributed to common shareholders	1,408.1	1,300.3	1,199.9
Reconciliation to cash provided by operating activities
Equity income in subsidiaries, net of distributions	(437.4)	(571.3)	(385.7)
Deferred income taxes, net	11.6	(1.9)	12.7
Loss on debt extinguishment	0.0	23.1	38.4
Change in -
Accounts receivable from related parties	(0.1)	0.1	0.0
Prepaid income taxes	21.1	(2.1)	(7.9)
Accounts payable to related parties	(3.5)	(26.2)	29.2
Accrued interest	15.4	0.4	(0.9)
Other current liabilities	(5.1)	8.2	(1.5)
Other, net	5.8	(2.5)	9.6
Net cash provided by operating activities	1,015.9	728.1	893.8
Investing activities
Capital contributions to subsidiaries	(1,099.7)	(734.0)	(1,026.1)
Return of capital from subsidiaries	372.9	196.1	602.8
Short-term notes receivable from related parties, net	(1.9)	81.8	(88.3)
Other, net	(2.0)	(1.1)	3.7
Net cash used in investing activities	(730.7)	(457.2)	(507.9)
Financing activities
Exercise of stock options	33.6	15.7	43.8
Purchase of common stock	(69.2)	(33.1)	(99.2)
Dividends paid on common stock	(917.9)	(854.8)	(798.0)
Issuance of long-term debt	900.0	1,100.0	1,650.0
Retirement of long-term debt	0.0	(300.0)	(1,430.0)
Issuance of short-term loan	0.0	0.0	340.0
Repayment of short-term loan	0.0	(340.0)	0.0
Change in commercial paper	(336.4)	255.7	145.7
Short-term notes payable to related parties, net	112.1	(82.6)	(186.3)
Payments for debt extinguishment and issuance costs	(6.7)	(33.9)	(47.3)
Other, net	(1.2)	(1.4)	(1.1)
Net cash used in financing activities	285.7	274.4	382.4
Net change in cash, cash equivalents, and restricted cash	(0.5)	(3.5)	3.5
Cash, cash equivalents, and restricted cash at beginning of year	0.5	4.0	0.5
Cash, cash equivalents, and restricted cash at end of year	$ 0.0	$ 0.5	$ 4.0