Revenue - disaggregation of sales - Schedule of Disaggregates of Net Sales of our Chemicals Segment (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenue - disaggregation of sales [Line Items]
Net sales	$ 559.7	$ 507.1	$ 1,090.3	$ 999.8
Chemicals
Revenue - disaggregation of sales [Line Items]
Net sales	500.5	443.2	979.3	869.5
Point of Origin | Chemicals
Revenue - disaggregation of sales [Line Items]
Net sales	500.5	443.2	979.3	869.5
Point of Origin | Chemicals | Eliminations
Revenue - disaggregation of sales [Line Items]
Net sales	(231.7)	(188.5)	(435.9)	(435.6)
Point of Origin | Chemicals | Operating Segment | United States
Revenue - disaggregation of sales [Line Items]
Net sales	279.7	233.4	520.6	489.2
Point of Origin | Chemicals | Operating Segment | Germany
Revenue - disaggregation of sales [Line Items]
Net sales	216.2	193.6	428.4	379.6
Point of Origin | Chemicals | Operating Segment | Canada
Revenue - disaggregation of sales [Line Items]
Net sales	97.6	83.9	186.9	174.8
Point of Origin | Chemicals | Operating Segment | Norway
Revenue - disaggregation of sales [Line Items]
Net sales	77.7	75.3	148.7	147.2
Point of Origin | Chemicals | Operating Segment | Belgium
Revenue - disaggregation of sales [Line Items]
Net sales	61.0	45.5	130.6	114.3
Point of Destination | Chemicals
Revenue - disaggregation of sales [Line Items]
Net sales	500.5	443.2	979.3	869.5
Point of Destination | Chemicals | Operating Segment | Europe
Revenue - disaggregation of sales [Line Items]
Net sales	222.6	199.0	437.5	400.1
Point of Destination | Chemicals | Operating Segment | North America
Revenue - disaggregation of sales [Line Items]
Net sales	182.5	153.0	348.5	301.6
Point of Destination | Chemicals | Operating Segment | Other
Revenue - disaggregation of sales [Line Items]
Net sales	$ 95.4	$ 91.2	$ 193.3	$ 167.8