Long-Term Debt - Debt Outstanding (Details) $ in Millions	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Nov. 15, 2021 USD ($) number_of_interest_rate_swaps
Long-term debt
Total	$ 15,559.8	$ 13,652.6
Integrys acquisition fair value adjustment	1.2	2.9
Long-term debt, including current portion	15,464.2	13,563.4
Unamortized debt issuance costs	(81.8)	(77.7)
Unamortized discount, net and other	(22.3)	(21.7)
Current portion of long-term debt	(808.5)	(91.0)
Long-term debt	14,655.7	13,472.4
Finance lease obligation	$ 183.2	$ 129.7
WE
Long-term debt
Weighted average interest rate	4.22%	4.13%
Unsecured debt	$ 3,285.0	$ 2,785.0
WEPCo Environmental Trust Finance I, LLC
Long-term debt
Weighted average interest rate	1.58%	1.58%
Secured debt	$ 105.9	$ 114.7
WPS
Long-term debt
Weighted average interest rate	4.11%	3.89%
Senior notes	$ 1,975.0	$ 1,675.0
WG
Long-term debt
Weighted average interest rate	3.35%	3.35%
Unsecured debt	$ 790.0	$ 790.0
Integrys \| 6.00% Integrys junior notes
Long-term debt
Weighted average interest rate	6.00%	6.00%
Unsecured debt	$ 221.4	$ 221.4
PGL
Long-term debt
Weighted average interest rate	3.41%	3.31%
Secured debt	$ 1,970.0	$ 1,870.0
PGL \| Collateralized First Mortgage Bonds
Long-term debt
Secured debt	$ 100.0
NSG
Long-term debt
Weighted average interest rate	3.56%	3.56%
Secured debt	$ 157.0	$ 157.0
MERC
Long-term debt
Weighted average interest rate	3.04%	3.04%
Senior notes	$ 210.0	$ 210.0
MGU
Long-term debt
Weighted average interest rate	3.18%	3.18%
Senior notes	$ 150.0	$ 150.0
UMERC
Long-term debt
Weighted average interest rate	3.26%	3.26%
Senior notes	$ 160.0	$ 160.0
Bluewater Gas Storage
Long-term debt
Weighted average interest rate	3.76%	3.76%
Senior notes	$ 112.6	$ 115.2
ATC Holding LLC
Long-term debt
Weighted average interest rate	4.05%	4.05%
Senior notes	$ 475.0	$ 475.0
We Power
Long-term debt
Weighted average interest rate	5.62%	5.60%
Secured debt	$ 896.5	$ 934.7
WECC
Long-term debt
Weighted average interest rate	6.94%	6.94%
Unsecured debt	$ 50.0	$ 50.0
WECI Wind Holding I
Long-term debt
Weighted average interest rate	2.75%	2.75%
Senior notes	$ 332.1	$ 374.6
WECI Wind Holding II
Long-term debt
Weighted average interest rate	6.38%	0.00%
Senior notes	$ 199.3	$ 0.0
Jayhawk Wind LLC
Long-term debt
Long-term debt, including current portion	$ 7.3	$ 7.3
WEC Energy Group
Long-term debt
Weighted average interest rate	2.44%	1.67%
Senior notes	$ 3,970.0	$ 3,070.0
Current portion of long-term debt	(700.0)	0.0
Long-term debt	$ 3,747.2	$ 3,549.8
WEC Energy Group \| WEC Energy Group junior notes due 2067
Long-term debt
Weighted average interest rate	6.72%	2.27%
Unsecured debt	$ 500.0	$ 500.0	$ 500.0
Interest rate	6.72%	2.27%
WEC Energy Group \| 6.20% WEC Energy Group senior notes
Long-term debt
Interest rate	6.20%
WEC Energy Group \| Interest rate swaps
Long-term debt
Number of interest rate swaps executed \| number_of_interest_rate_swaps			2
Interest rate swap fixed interest rate			4.9765%
Interest rate swap notional value			$ 250.0

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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