Revenue recognition - Disaggregation of Net Sales by Place of Manufacture and to Location of Customer (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	$ 509.8	$ 489.8
Point of origin
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	509.8	489.8
Point of origin \| Reportable geographical components \| United States
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	357.7	322.4
Point of origin \| Reportable geographical components \| Germany
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	226.6	216.8
Point of origin \| Reportable geographical components \| Canada
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	87.9	110.8
Point of origin \| Reportable geographical components \| Norway
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	66.1	70.5
Point of origin \| Reportable geographical components \| Belgium
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	64.2	65.7
Point of origin \| Eliminations
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	(292.7)	(296.4)
Point of destination
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	509.8	489.8
Point of destination \| Europe
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	243.1	228.5
Point of destination \| North America
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	186.2	190.2
Point of destination \| Other
Entity Wide Information Revenue from External Customer [Line Items]
Net sales	$ 80.5	$ 71.1