Segment Reporting - Reconciliation of Segment Information to Income Before Provision for Income Taxes (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Operating Income		$ 53,914	$ 40,004
Business restructuring		(81)	(357)
Interest expense, net		(1,524)	(1,230)
Other, net		746	(3,262)
Income before provision for income taxes		53,136	35,512
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating Income		73,794	47,656
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating Income		53,210	36,156
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating Income		17,951	7,516
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating Income		2,633	3,984
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	[1]	$ (19,799)	$ (7,295)

[1] Unallocated corporate expenses primarily comprise corporate administrative expenses (e.g., corporate finance, legal, human resources, information systems, deferred compensation and environmental remediation) that are not included in segment operating income and are not used to evaluate segment performance.