Segment Reporting - Reconciliation of Segment Information to Consolidated Financial Statements (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Operating income		$ 44,607	$ 35,178
Interest expense, net		(3,614)	(4,054)
Loss from equity in joint ventures			(1,240)
Other, net		(525)	652
Income Before Provision for Income Taxes		40,468	30,536
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income		61,775	50,793
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating income		37,245	33,764
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating income		22,197	14,785
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating income		2,333	2,244
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	[1]	$ (17,168)	$ (15,615)

[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 not used to evaluate segment performance.