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Short-Term Debt and Lines of Credit - Outstanding Amounts (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Short-term Debt [Line Items]
Issuance of short-term loan			$ 0.9	$ 340.0	$ 0.0
WE
Short-term Debt [Line Items]
Maximum debt to capitalization ratio			65.00%
WPS
Short-term Debt [Line Items]
Maximum debt to capitalization ratio			65.00%
WG
Short-term Debt [Line Items]
Maximum debt to capitalization ratio			65.00%
PGL
Short-term Debt [Line Items]
Maximum debt to capitalization ratio			65.00%
WEC Energy Group
Short-term Debt [Line Items]
Commercial paper outstanding			$ 736.1	820.4
Issuance of short-term loan			$ 0.0	340.0	$ 0.0
Maximum debt to capitalization ratio			70.00%
WEC Energy Group \| WEC Senior Notes 0.80% due 2024
Short-term Debt [Line Items]
Interest rate	0.80%
Commercial paper
Short-term Debt [Line Items]
Commercial paper outstanding			$ 1,896.1	$ 1,436.9
Average interest rate on amount outstanding			0.26%	0.21%
Average amount outstanding during the year			$ 1,480.0
Weighted- average interest rate during the year			0.18%
Term loan
Short-term Debt [Line Items]
Average interest rate on amount outstanding				0.99%
Term loan outstanding			$ 0.0	$ 340.0
Issuance of short-term loan		$ 340.0
Length of term loan		364 days
Term loan \| WEC Energy Group
Short-term Debt [Line Items]
Length of term loan	364 days
Operating expense loans
Short-term Debt [Line Items]
Term loan outstanding			$ 0.9	$ 0.0