v3.25.4
Benefit Plans and Other Postretirement Benefits, Fair value measurements of plan assets (Details) - Pension Plan [Member] - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Defined Benefit Plan Disclosure      
Fair value of pension plan assets $ 457.0 $ 444.5 $ 481.6
Defined Benefit Plan, Equity Securities, US, Large Cap [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 25.8 26.8  
U.S. equities - small/mid cap and other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 8.0 7.2  
International equities - growth      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 11.2 10.3  
International equities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 41.9 40.9  
Alternative investment funds      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.6 1.1  
U.S. fixed income securities - intermediate term      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 122.7 131.1  
Fixed Income Securities - Long Term [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 180.2 170.6  
International fixed income securities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 43.2 36.0  
Insurance contracts      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 18.3 17.8  
Defined Benefit Plan, Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 5.1 2.7  
Fair Value, Inputs, Level 1 [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 16.3 13.0  
Fair Value, Inputs, Level 1 [Member] | Defined Benefit Plan, Equity Securities, US, Large Cap [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 1 [Member] | U.S. equities - small/mid cap and other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 1 [Member] | International equities - growth      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 11.2 10.3  
Fair Value, Inputs, Level 1 [Member] | International equities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 1 [Member] | Alternative investment funds      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 1 [Member] | U.S. fixed income securities - intermediate term      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 1 [Member] | Fixed Income Securities - Long Term [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 1 [Member] | International fixed income securities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 1 [Member] | Insurance contracts      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 1 [Member] | Defined Benefit Plan, Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 5.1 2.7  
Fair Value, Inputs, Level 2 [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 421.8 412.6  
Fair Value, Inputs, Level 2 [Member] | Defined Benefit Plan, Equity Securities, US, Large Cap [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 25.8 26.8  
Fair Value, Inputs, Level 2 [Member] | U.S. equities - small/mid cap and other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 8.0 7.2  
Fair Value, Inputs, Level 2 [Member] | International equities - growth      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 2 [Member] | International equities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 41.9 40.9  
Fair Value, Inputs, Level 2 [Member] | Alternative investment funds      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 2 [Member] | U.S. fixed income securities - intermediate term      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 122.7 131.1  
Fair Value, Inputs, Level 2 [Member] | Fixed Income Securities - Long Term [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 180.2 170.6  
Fair Value, Inputs, Level 2 [Member] | International fixed income securities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 43.2 36.0  
Fair Value, Inputs, Level 2 [Member] | Insurance contracts      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 2 [Member] | Defined Benefit Plan, Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 3 [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 18.3 17.8 $ 19.5
Fair Value, Inputs, Level 3 [Member] | Defined Benefit Plan, Equity Securities, US, Large Cap [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 3 [Member] | U.S. equities - small/mid cap and other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 3 [Member] | International equities - growth      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 3 [Member] | International equities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 3 [Member] | Alternative investment funds      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 3 [Member] | U.S. fixed income securities - intermediate term      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 3 [Member] | Fixed Income Securities - Long Term [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 3 [Member] | International fixed income securities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value, Inputs, Level 3 [Member] | Insurance contracts      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 18.3 17.8  
Fair Value, Inputs, Level 3 [Member] | Defined Benefit Plan, Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value Measured at Net Asset Value Per Share [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.6 1.1  
Fair Value Measured at Net Asset Value Per Share [Member] | Defined Benefit Plan, Equity Securities, US, Large Cap [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value Measured at Net Asset Value Per Share [Member] | U.S. equities - small/mid cap and other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value Measured at Net Asset Value Per Share [Member] | International equities - growth      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value Measured at Net Asset Value Per Share [Member] | International equities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value Measured at Net Asset Value Per Share [Member] | Alternative investment funds      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.6 1.1  
Fair Value Measured at Net Asset Value Per Share [Member] | U.S. fixed income securities - intermediate term      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value Measured at Net Asset Value Per Share [Member] | Fixed Income Securities - Long Term [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value Measured at Net Asset Value Per Share [Member] | International fixed income securities - other      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value Measured at Net Asset Value Per Share [Member] | Insurance contracts      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets 0.0 0.0  
Fair Value Measured at Net Asset Value Per Share [Member] | Defined Benefit Plan, Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure      
Fair value of pension plan assets $ 0.0 $ 0.0