v3.26.1
Stockholders' equity - Schedule of Changes in Accumulated Other Comprehensive Loss (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Stockholders' equity        
Balance at beginning of period $ 745.0 $ 847.0 $ 751.1 $ 817.0
Balance at end of period 751.0 846.8 751.0 846.8
OPEB Plans        
Stockholders' equity        
Balance at beginning of period 0.7 0.3 0.7 0.3
Currency translation        
Stockholders' equity        
Balance at beginning of period (263.1) (282.7) (267.3) (300.0)
Other comprehensive income (loss) (4.2) 14.2   31.5
Balance at end of period (267.3) (268.5) (267.3) (268.5)
Accumulated Defined benefit pension plans | Defined benefit pension plans        
Stockholders' equity        
Balance at beginning of period (28.7) (63.4) (29.0) (63.8)
Other comprehensive income (loss) 0.3 0.4 0.6 0.8
Balance at end of period (28.4) (63.0) (28.4) (63.0)
Total Accumulated Other Comprehensive Loss        
Stockholders' equity        
Balance at beginning of period (291.1) (345.8) (295.6) (363.5)
Other comprehensive income (loss) (3.9) 14.6 0.6 32.3
Balance at end of period $ (295.0) $ (331.2) $ (295.0) $ (331.2)