Employee Benefits - Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Salaried VEBA
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 47.8	$ 42.9	$ 43.1
Pension Plans
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Defined Benefit Plan, Plan Assets, Amount	30.2	22.5	$ 20.5
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	82.1	76.6
Deferred compensation program - Diversified investment funds in registered investment companies	6.9	11.9
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	27.5	25.2
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	16.9	16.8
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	0.6	0.2
Level 1 | Pension Plans | 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	5.7	0.0
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	24.5	17.1
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	$ 0.0	$ 5.4