Segment Reporting - Reconciliation of Segment Information to Consolidated Financial Statements (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Operating income		$ 28,738	$ 38,794	$ 116,261	$ 102,567
Business restructuring				(1,061)
Interest expense, net		(2,824)	(3,837)	(9,855)	(10,760)
Loss from equity in joint ventures (Note 16)			(863)		(3,918)
Other, net		1,229	(981)	401	(94)
Income Before Provision for Income Taxes		27,143	33,113	106,807	87,795
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income		50,152	46,082	171,941	146,058
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating income		20,737	21,762	85,214	79,758
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating income		27,087	24,588	80,278	62,802
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating income		2,328	(268)	6,449	3,498
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	[1]	$ (21,414)	$ (7,288)	$ (54,619)	$ (43,491)

[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.