Segment Reporting - Reconciliation of Segment Information to Consolidated Financial Statements (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Segment Reporting Information [Line Items]
Operating income	$ 35,178		$ 22,523
Interest expense, net	(4,054)		(2,957)
Loss from equity in joint ventures	(1,240)		(1,451)
Other, net	652		(26)
Income Before Provision for Income Taxes	30,536		18,089
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income	50,793		33,185
Operating Segments [Member] | Surfactants [Member]
Segment Reporting Information [Line Items]
Operating income	33,764		18,338
Operating Segments [Member] | Polymers [Member]
Segment Reporting Information [Line Items]
Operating income	14,785		10,826
Operating Segments [Member] | Specialty Products [Member]
Segment Reporting Information [Line Items]
Operating income	2,244		4,021
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expenses	$ (15,615)	[1]	$ (10,662)	[1]

[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.