COMMON EQUITY - STOCK OPTIONS (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Options Activity
Outstanding, shares, beginning balance	78,619	69,145
Granted, shares		18,021	22,042	21,638
Exercised, shares		(9,600)
Transferred, shares		1,053
Outstanding, shares, ending balance		78,619	69,145
Options - Weighted Average Exercise Price
Outstanding, Weighted-Average Exercise Price, Beginning	$ 79.25	$ 74.01
Granted, Weighted-Average Exercise Price		91.06
Exercised, Weighted-Average Exercise Price		64.98
Transferred, Weighted-Average Exercise Price		91.06
Outstanding, Weighted-Average Exercise Price, Ending		$ 79.25	$ 74.01
Options - Additional Disclosures
Outstanding, Weighted-Average Remaining Contractual Life (Years)		7 years 6 months
Outstanding, Aggregate Intrinsic Value		$ 1.4
Exercisable, shares		27,947
Exercisable, Weighted-Average Exercise Price		$ 70.37
Exercisable, Weighted-Average Remaining Contractual Life (Years)		6 years 4 months 24 days
Exercisable, Aggregate Intrinsic Value		$ 0.7
Intrinsic value of options exercised		0.3	$ 0.9	$ 0.5
Tax benefit from option exercises		0.1	$ 0.3	$ 0.1
Compensation cost not yet recognized		$ 0.5
Weighted-average period over which unrecognized compensation cost is expected to be recognized		1 year 8 months 12 days
Estimated weighted-average fair value per stock option (in dollars per share)		$ 13.20	$ 10.82	$ 8.60
Subsequent event
Options Activity
Granted, shares	16,079
Options - Weighted Average Exercise Price
Granted, Weighted-Average Exercise Price	$ 96.04
Options - Additional Disclosures
Estimated weighted-average fair value per stock option (in dollars per share)	$ 14.71
WEC Energy Group
Options - Additional Disclosures
Cash received by WEC Energy Group from options exercised by WPS employees		$ 0.6	$ 1.5	$ 1.1