v3.26.1
Employee Benefits - Summary of Components of Net Periodic Postretirement Benefit Cost (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Defined Benefit Plan Disclosure [Line Items]    
Total net periodic postretirement and postemployment benefit cost $ 1.0 $ 1.2
Pension Plans    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 0.8 0.9
Interest cost 0.5 0.4
Expected return on plan assets (0.5) (0.4)
Amortization of prior service cost [1] 0.2 0.2
Total net periodic postretirement and postemployment benefit cost 1.0 1.1
Other Postretirement Benefits Plan    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 0.2 0.2
Interest cost 0.9 0.9
Amortization of net actuarial gain (0.3) (0.5)
Total net periodic postretirement and postemployment benefit cost 0.8 0.6
Postretirement Health Coverage | Salaried VEBA    
Defined Benefit Plan Disclosure [Line Items]    
Interest cost 0.5 0.5
Expected return on plan assets (0.6) (0.5)
Amortization of prior service cost [1] 0.7 0.7
Amortization of net actuarial gain (0.3) (0.1)
Total net periodic postretirement and postemployment benefit cost $ 0.3 $ 0.6
[1] We amortize prior service cost on a straight-line basis over the average remaining years of service of the active plan participants.