Goodwill and Other Intangible Assets - Schedule of Changes in Carrying Value of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 28,775	$ 14,732
Accumulated impairment loss, Beginning Balance	(3,467)	(3,467)
Goodwill net, Beginning Balance	25,308	11,265
Goodwill acquired		14,327
Goodwill measurement period adjustment	(120)
Foreign currency translation	(70)	(284)
Goodwill, Ending Balance	28,585	28,775
Accumulated impairment loss, Ending Balance	(3,467)	(3,467)
Goodwill net, Ending Balance	25,118	25,308
Surfactants Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	22,958	8,869
Accumulated impairment loss, Beginning Balance	(3,467)	(3,467)
Goodwill net, Beginning Balance	19,491	5,402
Goodwill acquired		14,327
Goodwill measurement period adjustment	(120)
Foreign currency translation	(211)	(238)
Goodwill, Ending Balance	22,627	22,958
Accumulated impairment loss, Ending Balance	(3,467)	(3,467)
Goodwill net, Ending Balance	19,160	19,491
Polymer Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	5,334	5,380
Goodwill net, Beginning Balance	5,334	5,380
Foreign currency translation	141	(46)
Goodwill, Ending Balance	5,475	5,334
Goodwill net, Ending Balance	5,475	5,334
Specialty Products Segment [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	483	483
Goodwill net, Beginning Balance	483	483
Goodwill, Ending Balance	483	483
Goodwill net, Ending Balance	$ 483	$ 483