Segment Reporting - Reconciliation of Segment Information to Consolidated Financial Statements (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Operating income		$ 42,916	$ 28,595	$ 87,523	$ 63,773
Business restructuring		(1,061)		(1,061)
Interest expense, net		(3,417)	(2,869)	(7,031)	(6,923)
Loss from equity in joint ventures (Note 16)			(1,815)		(3,055)
Other, net		(303)	235	(828)	887
Income Before Provision for Income Taxes		39,196	24,146	79,664	54,682
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income		60,014	49,183	121,789	99,976
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating income		27,232	24,232	64,477	57,996
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating income		30,994	23,429	53,191	38,214
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating income		1,788	1,522	4,121	3,766
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	[1]	$ (16,037)	$ (20,588)	$ (33,205)	$ (36,203)

[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.