Long-Term Debt - Issuances and Redemptions (Details) - USD ($) $ in Millions			1 Months Ended						12 Months Ended
	Feb. 07, 2024	Aug. 15, 2023	Nov. 30, 2023	Sep. 30, 2023	Aug. 31, 2023	Apr. 30, 2023	Mar. 31, 2023	Jan. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jul. 01, 2023	Nov. 15, 2021
Long-term debt
Gain on Extinguishment of Debt									$ 0.0	$ 0.0	$ (36.3)
6.00% Integrys junior notes | Integrys Holding
Long-term debt
Interest rate					6.00%		6.00%
Unsecured debt							$ 221.4
Early repayment of long-term debt							18.6
Extinguishment of debt					$ 202.5		$ 18.9
PGL Series NNN Bonds 5.82% due 2029 | PGL
Long-term debt
Issuance of debt			$ 100.0
Interest rate			5.82%
NSG Series T Bonds 5.82% due 2029 | NSG
Long-term debt
Issuance of debt			$ 20.0
Interest rate			5.82%
WEC Energy Group
Long-term debt
Gain on Extinguishment of Debt									$ 0.0	$ 0.0	$ (23.1)
WEC Energy Group | WEC Energy Group junior notes due 2067
Long-term debt
Interest rate									7.75%	6.72%
Unsecured debt		$ 500.0							$ 500.0	$ 500.0		$ 500.0	$ 500.0
Basis points added to three-month LIBOR rate		0.26161%
WEC Energy Group | WEC Energy Group junior notes due 2067 | Subsequent event
Long-term debt
Unsecured debt	$ 500.0
Early repayment of long-term debt	115.2
Extinguishment of debt	122.1
Gain on Extinguishment of Debt	$ 6.9
WEC Energy Group | WEC 4.75% Senior Notes due January 9, 2026
Long-term debt
Issuance of debt						$ 350.0		$ 650.0
Interest rate						4.75%		4.75%
WEC Energy Group | WEC 4.75% $450M Senior Notes due January 15, 2028
Long-term debt
Issuance of debt								$ 450.0
Interest rate								4.75%
WEC Energy Group | WEC 5.60% Senior Notes due September 12, 2026
Long-term debt
Issuance of debt				$ 600.0
Interest rate				5.60%
WEC Energy Group | WEC 0.55% Senior Notes due September 15, 2023
Long-term debt
Interest rate				0.55%
Early repayment of long-term debt				$ 700.0