Disaggregation of Sales - Schedule of Disaggregates of Net Sales of our Chemicals Segment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Net sales	$ 2,296.4	$ 1,849.7	$ 1,897.5
Point of Origin
Disaggregation Of Revenue [Line Items]
Net sales	2,296.4	1,849.7	1,897.5
Point of Origin | U.S.
Disaggregation Of Revenue [Line Items]
Net sales	1,409.1	1,189.8	1,164.8
Point of Origin | Germany
Disaggregation Of Revenue [Line Items]
Net sales	971.7	836.0	883.6
Point of Origin | Canada
Disaggregation Of Revenue [Line Items]
Net sales	371.9	319.5	328.7
Point of Origin | Belgium
Disaggregation Of Revenue [Line Items]
Net sales	295.7	249.5	270.7
Point of Origin | Norway
Disaggregation Of Revenue [Line Items]
Net sales	257.2	211.8	192.2
Point of Origin | Eliminations
Disaggregation Of Revenue [Line Items]
Net sales	(1,009.2)	(956.9)	(942.5)
Point of Destination
Disaggregation Of Revenue [Line Items]
Net sales	2,296.4	1,849.7	1,897.5
Point of Destination | Europe
Disaggregation Of Revenue [Line Items]
Net sales	945.7	783.8	824.2
Point of Destination | North America
Disaggregation Of Revenue [Line Items]
Net sales	999.7	778.2	740.1
Chemicals
Disaggregation Of Revenue [Line Items]
Net sales	1,939.4	1,638.8	1,731.2
Chemicals | Point of Origin
Disaggregation Of Revenue [Line Items]
Net sales	1,939.4	1,638.8	1,731.2
Chemicals | Point of Origin | U.S.
Disaggregation Of Revenue [Line Items]
Net sales	1,052.1	978.8	998.5
Chemicals | Point of Origin | Germany
Disaggregation Of Revenue [Line Items]
Net sales	971.7	836.0	883.6
Chemicals | Point of Origin | Canada
Disaggregation Of Revenue [Line Items]
Net sales	371.9	319.5	328.7
Chemicals | Point of Origin | Belgium
Disaggregation Of Revenue [Line Items]
Net sales	295.7	249.5	270.7
Chemicals | Point of Origin | Norway
Disaggregation Of Revenue [Line Items]
Net sales	257.2	211.8	192.2
Chemicals | Point of Origin | Eliminations
Disaggregation Of Revenue [Line Items]
Net sales	(1,009.2)	(956.8)	(942.5)
Chemicals | Point of Destination
Disaggregation Of Revenue [Line Items]
Net sales	1,939.4	1,638.8	1,731.2
Chemicals | Point of Destination | Europe
Disaggregation Of Revenue [Line Items]
Net sales	945.0	783.2	823.5
Chemicals | Point of Destination | North America
Disaggregation Of Revenue [Line Items]
Net sales	645.7	569.3	575.6
Chemicals | Point of Destination | Other
Disaggregation Of Revenue [Line Items]
Net sales	$ 348.7	$ 286.3	$ 332.1