Segment Reporting - Reconciliation of Segment Information to Consolidated Financial Statements (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Operating income		$ 46,059	$ 44,607
Business restructuring		(786)
Interest expense, net		(2,992)	(3,614)
Other, net		1,263	(525)
Income Before Provision for Income Taxes		44,330	40,468
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income		60,911	61,775
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating income		38,237	37,245
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating income		21,399	22,197
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating income		1,275	2,333
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	[1]	$ (14,066)	$ (17,168)

[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.