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Long-Term Debt - Issuances and Redemptions (Details) - USD ($) $ in Millions	1 Months Ended							12 Months Ended
	Dec. 31, 2021	Nov. 30, 2021	Oct. 31, 2021	Jun. 30, 2021	May 31, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Long-term debt
Loss on debt extinguishment								$ (36.3)	$ (38.4)	$ 0.0
Term loan
Long-term debt
Length of term loan							364 days
WE
Long-term debt
Unsecured debt	$ 2,785.0							2,785.0	2,785.0
WG
Long-term debt
Unsecured debt	790.0							790.0	640.0
WE Debentures 1.70% due 2028 \| WE
Long-term debt
Issuance of debt				$ 300.0
Interest rate				1.70%
WE Debentures 2.95% due 2021 \| WE
Long-term debt
Interest rate				2.95%
Early repayment of long-term debt				$ 300.0
WEPCo Environmental Trust Bonds 1.578%, due 2035 \| WEPCo Environmental Trust Finance I, LLC
Long-term debt
Issuance of debt					$ 118.8
Interest rate					1.578%
WPS Senior Notes 2.85% due 2051 \| WPS
Long-term debt
Issuance of debt		$ 450.0
Interest rate		2.85%
WPS Senior Notes 3.35% due 2021 \| WPS
Long-term debt
Interest rate		3.35%
Early repayment of long-term debt		$ 400.0
WG Debentures 2.07% due 2028 \| WG
Long-term debt
Issuance of debt		$ 150.0
Interest rate		2.07%
Integrys Holding Inc Junior Notes Due 2073 \| Integrys Holding
Long-term debt
Early repayment of long-term debt			$ 196.4
Extinguishment of debt			178.6
Unsecured debt			400.0
Loss on debt extinguishment			$ 13.2
PGL Series LLL Bonds 2.20% due 2028 \| PGL
Long-term debt
Issuance of debt		$ 200.0
Interest rate		2.20%
NSG Series S Bonds 2.20% 2028 \| NSG
Long-term debt
Issuance of debt		$ 25.0
Interest rate		2.20%
MERC Senior Notes 2.07% 2028 \| MERC
Long-term debt
Issuance of debt		$ 40.0
Interest rate		2.07%
WEC Energy Group
Long-term debt
Loss on debt extinguishment								$ (23.1)	$ (38.4)	$ 0.0
WEC Energy Group \| Term loan
Long-term debt
Repayments of Short-term Debt						$ 340.0
Length of term loan						364 days
WEC Energy Group \| WEC Senior Notes 0.80% due 2024
Long-term debt
Issuance of debt						$ 600.0
Interest rate						0.80%
WEC Energy Group \| WEC Senior Notes 2.20% due 2028
Long-term debt
Issuance of debt	$ 500.0
Interest rate	2.20%							2.20%
WEC Energy Group \| WEC Senior Notes 3.55% due 2025
Long-term debt
Interest rate	3.55%							3.55%
Early repayment of long-term debt	$ 300.0
Unsecured debt	420.0							$ 420.0
Loss on debt extinguishment	$ 23.1