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Long-Term Debt - Debt Outstanding (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Aug. 15, 2023 | Jul. 01, 2023 | Dec. 31, 2022 | Nov. 15, 2021
--- | --- | --- | --- | --- | ---
Long-term debt |  |  |  |  |
Total | $ 16,724.3 |  |  | $ 15,559.8 |
Integrys acquisition fair value adjustment | 0.0 |  |  | 1.2 |
Long-term debt, including current portion | 16,631.1 |  |  | 15,464.2 |
Unamortized debt issuance costs | (80.2) |  |  | (81.8) |
Unamortized discount, net and other | (20.5) |  |  | (22.3) |
Current portion of long-term debt | (1,264.2) |  |  | (808.5) |
Long-term debt | 15,366.9 |  |  | 14,655.7 |
Finance lease obligation | $ 145.9 |  |  | $ 183.2 |
WE |  |  |  |  |
Long-term debt |  |  |  |  |
Weighted average interest rate | 4.22% |  |  | 4.22% |
Unsecured debt | $ 3,285.0 |  |  | $ 3,285.0 |
WEPCo Environmental Trust Finance I, LLC |  |  |  |  |
Long-term debt |  |  |  |  |
Weighted average interest rate | 1.58% |  |  | 1.58% |
Secured debt | $ 97.0 |  |  | $ 105.9 |
WPS |  |  |  |  |
Long-term debt |  |  |  |  |
Weighted average interest rate | 4.11% |  |  | 4.11% |
Senior notes | $ 1,975.0 |  |  | $ 1,975.0 |
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 | 0.00% |  |  | 6.00% |
Unsecured debt | $ 0.0 |  |  | $ 221.4 |
PGL |  |  |  |  |
Long-term debt |  |  |  |  |
Weighted average interest rate | 3.53% |  |  | 3.41% |
Secured debt | $ 2,070.0 |  |  | $ 1,970.0 |
PGL | Collateralized First Mortgage Bonds |  |  |  |  |
Long-term debt |  |  |  |  |
Secured debt | $ 100.0 |  |  |  |
NSG |  |  |  |  |
Long-term debt |  |  |  |  |
Weighted average interest rate | 3.81% |  |  | 3.56% |
Secured debt | $ 177.0 |  |  | $ 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 | $ 109.8 |  |  | $ 112.6 |
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 | 5.65% |  |  | 5.62% |
Secured debt | $ 856.4 |  |  | $ 896.5 |
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 | $ 307.7 |  |  | $ 332.1 |
WECI Wind Holding II |  |  |  |  |
Long-term debt |  |  |  |  |
Weighted average interest rate | 6.38% |  |  | 6.38% |
Senior notes | $ 191.4 |  |  | $ 199.3 |
Jayhawk Wind LLC |  |  |  |  |
Long-term debt |  |  |  |  |
Long-term debt, including current portion | $ 7.5 |  |  | $ 7.3 |
WEC Energy Group |  |  |  |  |
Long-term debt |  |  |  |  |
Weighted average interest rate | 3.68% |  |  | 2.44% |
Senior notes | $ 5,320.0 |  |  | $ 3,970.0 |
Current portion of long-term debt | (600.0) |  |  | (700.0) |
Long-term debt | $ 5,192.8 |  |  | $ 3,747.2 |
WEC Energy Group | WEC Energy Group junior notes due 2067 |  |  |  |  |
Long-term debt |  |  |  |  |
Weighted average interest rate | 7.75% |  |  | 6.72% |
Unsecured debt | $ 500.0 | $ 500.0 | $ 500.0 | $ 500.0 | $ 500.0
Interest rate | 7.75% |  |  | 6.72% |
WEC Energy Group | 6.20% WEC Energy Group senior notes |  |  |  |  |
Long-term debt |  |  |  |  |
Interest rate | 6.20% |  |  |  |

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