v3.25.4
Income taxes - Components of Net Deferred Tax Asset (Liability) (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Tax effect of temporary differences related to:    
Lease assets $ 5.0 $ 5.2
Accrued pension costs 0.9 14.3
Accrued environmental liabilities 2.9 15.2
Capitalized research and development costs 8.5 6.3
Other deductible differences 14.7 12.0
Investments in subsidiaries and affiliates 7.4 10.1
Tax loss and tax credit carryforwards 152.9 126.6
Valuation allowance (45.7) (14.1)
Adjusted gross deferred tax assets 146.6 175.6
Netting of items by tax jurisdiction, assets (111.4) (121.8)
Net noncurrent deferred tax asset 35.2 53.8
Tax effect of temporary differences related to:    
Property and equipment (66.1) (69.1)
Lease liabilities (5.1) (5.3)
Other taxable differences (20.3) (22.6)
Investments in subsidiaries and affiliates (57.0) (56.9)
Unrecognized foreign currency gain (11.1) (16.8)
Tax on unremitted earnings of non-U.S. subsidiaries (7.6) (8.8)
Adjusted gross deferred tax liabilities (167.2) (179.5)
Netting of items by tax jurisdiction, liabilities (111.4) (121.8)
Net noncurrent deferred tax liability $ (55.8) $ (57.7)