v3.26.1
Pension obligations (Schedule of fair value of plan assets) - (Details) - Pension obligations [Member] - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Pension Obligations [Line Items]      
Plan assets, at fair value $ 94.5 $ 94.2 $ 106.0
Level 1 [Member]      
Pension Obligations [Line Items]      
Plan assets, at fair value 35.6 34.1  
Level 2 [Member]      
Pension Obligations [Line Items]      
Plan assets, at fair value 58.9 60.1  
Level 3 [Member]      
Pension Obligations [Line Items]      
Plan assets, at fair value 0.0 0.0  
Money market instruments [Member]      
Pension Obligations [Line Items]      
Cash and cash equivalents, amount contributed to fair value of plan assets 1.0 1.1  
Money market instruments [Member] | Level 1 [Member]      
Pension Obligations [Line Items]      
Cash and cash equivalents, amount contributed to fair value of plan assets 1.0 1.1  
Money market instruments [Member] | Level 2 [Member]      
Pension Obligations [Line Items]      
Cash and cash equivalents, amount contributed to fair value of plan assets 0.0 0.0  
Money market instruments [Member] | Level 3 [Member]      
Pension Obligations [Line Items]      
Cash and cash equivalents, amount contributed to fair value of plan assets 0.0 0.0  
Pooled equity funds [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 34.6 33.0  
Pooled equity funds [Member] | Level 1 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 34.6 33.0  
Pooled equity funds [Member] | Level 2 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0.0 0.0  
Pooled equity funds [Member] | Level 3 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0.0 0.0  
Pooled fixed income funds [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 58.5 59.6  
Pooled fixed income funds [Member] | Level 1 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0.0 0.0  
Pooled fixed income funds [Member] | Level 2 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 58.5 59.6  
Pooled fixed income funds [Member] | Level 3 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0.0 0.0  
Balanced funds [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0.4 0.5  
Balanced funds [Member] | Level 1 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0.0 0.0  
Balanced funds [Member] | Level 2 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets 0.4 0.5  
Balanced funds [Member] | Level 3 [Member]      
Pension Obligations [Line Items]      
Investment funds, amount contributed to fair value of plan assets $ 0.0 $ 0.0