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