Revenue - Disaggregation of Sales - Schedule of Disaggregates of Net Sales of our Chemicals Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation Of Revenue [Line Items]
Net sales	$ 468.9	$ 556.3	$ 1,468.7	$ 1,819.9
Chemicals
Disaggregation Of Revenue [Line Items]
Net sales	396.9	459.6	1,266.4	1,587.8
Point of Origin | Chemicals
Disaggregation Of Revenue [Line Items]
Net sales	396.9	459.6	1,266.4	1,587.8
Point of Origin | Chemicals | United States
Disaggregation Of Revenue [Line Items]
Net sales	250.6	330.3	739.8	980.4
Point of Origin | Chemicals | Germany
Disaggregation Of Revenue [Line Items]
Net sales	182.3	213.5	561.9	762.0
Point of Origin | Chemicals | Canada
Disaggregation Of Revenue [Line Items]
Net sales	93.0	105.1	267.8	313.1
Point of Origin | Chemicals | Belgium
Disaggregation Of Revenue [Line Items]
Net sales	49.3	76.0	163.6	256.3
Point of Origin | Chemicals | Norway
Disaggregation Of Revenue [Line Items]
Net sales	40.7	64.7	187.9	211.1
Point of Origin | Chemicals | Eliminations
Disaggregation Of Revenue [Line Items]
Net sales	(219.0)	(330.0)	(654.6)	(935.1)
Point of Destination | Chemicals
Disaggregation Of Revenue [Line Items]
Net sales	396.9	459.6	1,266.4	1,587.8
Point of Destination | Chemicals | Europe
Disaggregation Of Revenue [Line Items]
Net sales	179.9	197.5	580.0	731.6
Point of Destination | Chemicals | North America
Disaggregation Of Revenue [Line Items]
Net sales	165.1	182.5	466.7	558.4
Point of Destination | Chemicals | Other
Disaggregation Of Revenue [Line Items]
Net sales	$ 51.9	$ 79.6	$ 219.7	$ 297.8