v3.25.4
Intangible assets - Components and Movements (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Intangible assets    
Beginning balance $ 109.8 $ 102.0
Ending balance 109.4 109.8
Cost    
Intangible assets    
Beginning balance 292.9 272.9
Additions 19.6 21.2
Disposals   (1.1)
Effect of movements in exchange rates (0.1) (0.1)
Ending balance 312.4 292.9
Amortization and impairment losses    
Intangible assets    
Beginning balance 183.1 170.9
Amortization   13.5
Impairment   (1.1)
Effect of movements in exchange rates 19.9 (0.2)
Ending balance 203.0 183.1
Software (mostly development costs)    
Intangible assets    
Beginning balance 109.6 101.7
Ending balance 109.4 109.6
Software (mostly development costs) | Cost    
Intangible assets    
Beginning balance 289.5 268.4
Additions 19.6 21.2
Effect of movements in exchange rates (0.1) (0.1)
Ending balance 309.0 289.5
Software (mostly development costs) | Amortization and impairment losses    
Intangible assets    
Beginning balance 179.9 166.7
Amortization 19.7 13.4
Effect of movements in exchange rates   (0.2)
Ending balance 199.6 179.9
Other intangible assets    
Intangible assets    
Beginning balance 0.2 0.3
Ending balance   0.2
Other intangible assets | Cost    
Intangible assets    
Beginning balance 3.4 4.5
Disposals   (1.1)
Ending balance 3.4 3.4
Other intangible assets | Amortization and impairment losses    
Intangible assets    
Beginning balance 3.2 4.2
Amortization 0.2 0.1
Disposals   (1.1)
Ending balance $ 3.4 $ 3.2