v3.25.1
Employee Benefit Plans Net Periodic Benefit Cost (Detail) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Pension Plan | UNITED STATES    
Defined Benefit Plans and Other Postretirement Benefit Plans    
Service Cost $ 2.4 $ 2.3
Interest Cost 21.4 20.7
Expected Return on Plan Assets (21.8) (22.8)
Amortization of Net Actuarial (Gain) Loss 3.7 3.7
Amortization of Prior Service Credit 0.0 0.0
Net Periodic Benefit Cost (Credit) 5.7 3.9
Pension Plan | UNITED KINGDOM    
Defined Benefit Plans and Other Postretirement Benefit Plans    
Service Cost 0.0 0.0
Interest Cost 2.1 1.9
Expected Return on Plan Assets (2.2) (2.1)
Amortization of Net Actuarial (Gain) Loss 0.7 0.7
Amortization of Prior Service Credit 0.0 0.0
Net Periodic Benefit Cost (Credit) 0.6 0.5
Other Postretirement Benefit Plans    
Defined Benefit Plans and Other Postretirement Benefit Plans    
Service Cost 0.0 0.0
Interest Cost 1.0 1.0
Expected Return on Plan Assets (0.1) (0.1)
Amortization of Net Actuarial (Gain) Loss (0.3) (0.2)
Amortization of Prior Service Credit (0.1) (0.1)
Net Periodic Benefit Cost (Credit) $ 0.5 $ 0.6