v3.26.3
Accumulated other comprehensive income (loss) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Balance at beginning of period $ 219.1 $ 890.8 $ 228.1 $ 762.7
Balance at end of period 346.2 951.4 346.2 951.4
Currency translation reserve        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Balance at beginning of period (7.5) (14.1) (23.5) (51.7)
Other comprehensive income (loss), net of taxes 0.3 1.5 16.3 39.1
Reclass from AOCI, net of taxes 0.0 0.0 0.0 0.0
Balance at end of period (7.2) (12.6) (7.2) (12.6)
Other comprehensive income (loss), tax 0.0 0.0 0.0 0.0
Reclass from AOCI, tax 0.0 0.0 0.0 0.0
Cash flow hedge reserve        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Balance at beginning of period (10.1) (10.8) (0.6) (3.3)
Other comprehensive income (loss), net of taxes 11.7 8.5 4.6 (0.1)
Reclass from AOCI, net of taxes 0.5 0.7 (1.9) 1.8
Balance at end of period 2.1 (1.6) 2.1 (1.6)
Other comprehensive income (loss), tax (4.5) (0.6) (3.2) 0.2
Reclass from AOCI, tax 0.3 (0.2) 0.7 1.0
Defined benefit plans reserve        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Balance at beginning of period 2.5 0.4 3.5 (0.2)
Other comprehensive income (loss), net of taxes 1.6 0.0 0.6 0.6
Reclass from AOCI, net of taxes (0.0) (0.0) (0.0) (0.0)
Balance at end of period 4.1 0.4 4.1 0.4
Other comprehensive income (loss), tax (0.8) 0.0 0.1 (0.3)
Reclass from AOCI, tax 0.0 0.0 0.0 0.0
Total        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Balance at beginning of period (15.1) (24.5) (20.6) (55.2)
Other comprehensive income (loss), net of taxes 13.6 10.0 21.5 39.6
Reclass from AOCI, net of taxes 0.5 0.7 (1.9) 1.8
Balance at end of period $ (1.0) $ (13.8) $ (1.0) $ (13.8)