v3.25.2
Retirement and Postretirement Plans - Components of Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Pension        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Service cost $ 2.2 $ 2.3 $ 4.4 $ 4.7
Interest cost 7.4 8.2 14.8 16.9
Expected return on plan assets (8.1) (8.8) (16.2) (18.1)
Amortization of prior service cost 0.3 0.3 0.6 0.6
Net remeasurement losses (gains)   1.0   1.8
Net Periodic Benefit Cost (Income) 1.8 3.0 3.6 5.9
Pension | United States of America | Bargaining Plan        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Service cost 2.2 2.2 4.4 4.4
Interest cost 6.5 6.4 13.0 12.8
Expected return on plan assets (7.5) (7.0) (15.0) (14.0)
Amortization of prior service cost 0.3 0.3 0.6 0.6
Net Periodic Benefit Cost (Income) 1.5 1.9 3.0 3.8
Pension | United States of America | Salaried Plan        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Service cost   0.1   0.3
Interest cost   1.0   2.5
Expected return on plan assets   (1.1)   (2.7)
Net remeasurement losses (gains)   1.0   1.8
Net Periodic Benefit Cost (Income)   1.0   1.9
Pension | United States of America | Supplemental Plan        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Interest cost 0.2 0.2 0.4 0.4
Net Periodic Benefit Cost (Income) 0.2 0.2 0.4 0.4
Pension | United Kingdom | Pension Scheme        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Interest cost 0.7 0.6 1.4 1.2
Expected return on plan assets (0.6) (0.7) (1.2) (1.4)
Net Periodic Benefit Cost (Income) 0.1 (0.1) 0.2 (0.2)
Postretirement        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Service cost 0.1 0.1 0.2 0.2
Interest cost 1.1 1.1 2.2 2.2
Expected return on plan assets (0.7) (0.7) (1.4) (1.4)
Amortization of prior service cost (1.5) (1.5) (3.0) (3.0)
Net Periodic Benefit Cost (Income) $ (1.0) $ (1.0) $ (2.0) $ (2.0)