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, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation Of Revenue [Line Items]
Net sales	$ 507.1	$ 634.6	$ 999.8	$ 1,263.6
Chemicals
Disaggregation Of Revenue [Line Items]
Net sales	443.2	565.3	869.5	1,128.2
Point of Origin | Chemicals
Disaggregation Of Revenue [Line Items]
Net sales	443.2	565.3	869.5	1,128.2
Point of Origin | Chemicals | United States
Disaggregation Of Revenue [Line Items]
Net sales	233.4	323.7	489.2	650.1
Point of Origin | Chemicals | Germany
Disaggregation Of Revenue [Line Items]
Net sales	193.6	272.0	379.6	548.5
Point of Origin | Chemicals | Canada
Disaggregation Of Revenue [Line Items]
Net sales	83.9	111.6	174.8	208.0
Point of Origin | Chemicals | Belgium
Disaggregation Of Revenue [Line Items]
Net sales	45.5	87.5	114.3	180.3
Point of Origin | Chemicals | Norway
Disaggregation Of Revenue [Line Items]
Net sales	75.3	68.0	147.2	146.4
Point of Origin | Chemicals | Eliminations
Disaggregation Of Revenue [Line Items]
Net sales	(188.5)	(297.5)	(435.6)	(605.1)
Point of Destination | Chemicals
Disaggregation Of Revenue [Line Items]
Net sales	443.2	565.3	869.5	1,128.2
Point of Destination | Chemicals | Europe
Disaggregation Of Revenue [Line Items]
Net sales	199.0	264.6	400.1	534.1
Point of Destination | Chemicals | North America
Disaggregation Of Revenue [Line Items]
Net sales	153.0	196.0	301.6	375.9
Point of Destination | Chemicals | Other
Disaggregation Of Revenue [Line Items]
Net sales	$ 91.2	$ 104.7	$ 167.8	$ 218.2