Segment Reporting - Reconciliation of Segment Information to Income Before Provision for Income Taxes (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Operating Income		$ 40,004	$ 29,738
Business restructuring		(357)	(733)
Interest expense, net		(1,230)	(1,853)
Other, net		(3,262)	3,145
Income before provision for income taxes		35,512	31,030
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating Income		47,656	52,403
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating Income		36,156	37,167
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating Income		7,516	12,105
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating Income		3,984	3,131
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	[1]	$ (7,295)	$ (21,932)

[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.