v3.26.3
Retirement Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Jun. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Defined Benefit Plan Disclosure [Line Items]          
Net loss (gain)   $ 18.0 $ (67.1)    
Defined Benefit Pension Plan          
Defined Benefit Plan Disclosure [Line Items]          
Service cost $ 3.5 4.0   $ 10.6 $ 11.4
Interest cost 5.5 5.2   16.8 14.9
Expected return on assets (5.2) (5.4)   (15.8) (15.4)
Net loss (gain) (0.2)     (0.5) 0.2
Prior service cost 0.2 0.2   0.5 0.5
Total benefit cost 3.8 4.0   11.6 11.6
Retiree Health Care Plan          
Defined Benefit Plan Disclosure [Line Items]          
Interest cost 0.1 0.1   0.3 0.3
Prior service cost (0.2) (0.2)   (0.6) (0.6)
Total benefit cost $ (0.1) $ (0.1)   $ (0.3) $ (0.3)