Segment Reporting - Reconciliation of Segment Information to Income Before Provision for Income Taxes (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Operating Income		$ 18,667	$ 17,809	$ 38,836	$ 38,866
Business restructuring			(42)		(199)
Other Income (Expense)
Interest, net		(2,661)	(3,865)	(5,732)	(6,687)
Other, net		1,200	2,370	3,562	4,038
Income before provision for income taxes		17,206	16,314	36,666	36,217
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating Income		37,978	35,234	76,708	74,823
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating Income		17,062	15,140	43,142	42,196
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating Income		13,597	16,321	21,979	26,325
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating Income		7,319	3,773	11,587	6,302
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	[1]	$ (19,311)	$ (17,383)	$ (37,872)	$ (35,758)

[1] Unallocated corporate expenses are primarily comprised of 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. Unallocated corporate expenses for the three and six months periods ended June 30, 2024 also include a $3,500,000 pre-tax charge related to a criminal social engineering scheme that impacted one of the Company's Asia subsidiaries. See Note 17, Other Matter, below for detailed information about the charge.