v3.25.2
Reclassifications out of Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Detail) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance $ 1,211.2  
Other comprehensive income/(loss) before reclassifications 57.6 $ (12.6)
Amounts reclassified from AOCL 0.0 0.1
Total other comprehensive income/(loss) 57.6 (12.5)
Ending Balance 1,295.4  
Accumulated Other Comprehensive Loss [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance (91.0) (148.1)
Ending Balance (33.4) (160.6)
Defined Benefit Pension Plan Items [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance 0.0 (77.2)
Other comprehensive income/(loss) before reclassifications 0.0 0.0
Amounts reclassified from AOCL 0.0 0.1
Total other comprehensive income/(loss) 0.0 0.1
Ending Balance 0.0 (77.1)
Foreign Currency Translation Items [Member]    
Accumulated Other Comprehensive Income (Loss) [Line Items]    
Beginning Balance (91.0) (70.9)
Other comprehensive income/(loss) before reclassifications 57.6 (12.6)
Amounts reclassified from AOCL 0.0 0.0
Total other comprehensive income/(loss) 57.6 (12.6)
Ending Balance $ (33.4) $ (83.5)