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Employee Benefits - Fair Value of Plan Assets (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | --- | ---
Salaried VEBA |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 42.9 | $ 43.1 | $ 42.4
Pension Plans |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 22.5 | 20.5 | $ 14.9
Level 1 | Fair Value, Measurements, Recurring |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 76.6 | 73.6 |
Deferred compensation program - Diversified investment funds in registered investment companies | 11.9 | 11.1 |
Level 1 | Postretirement Health Coverage | Salaried VEBA | Equity Funds | Fair Value, Measurements, Recurring |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 25.2 | 25.5 |
Level 1 | Postretirement Health Coverage | Salaried VEBA | Fixed Income Funds | Fair Value, Measurements, Recurring |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 16.8 | 16.5 |
Level 1 | Postretirement Health Coverage | Salaried VEBA | Cash and Money Market Investments | Fair Value, Measurements, Recurring |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.2 |  |
Level 1 | Pension Plans | DiversifiedInvestment Funds in Pooled Separate Accounts | Fair Value, Measurements, Recurring |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 17.1 | 11.2 |
Level 1 | Pension Plans | Diversified Investment Funds In Registered Investment Companies | Fair Value, Measurements, Recurring |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 5.4 | $ 9.3 |

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