SEGMENT INFORMATION - Business Segment Net Sales (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Disclosure of Other Information about Entity's Reportable Segments [Abstract]
Net sales	$ 643,679	$ 594,790	$ 553,204
Human Nutrition & Health | Operating Segments
Segment Reporting, Disclosure of Other Information about Entity's Reportable Segments [Abstract]
Net sales	341,237	315,796	297,134
Animal Nutrition & Health | Operating Segments
Segment Reporting, Disclosure of Other Information about Entity's Reportable Segments [Abstract]
Net sales	175,693	157,688	161,119
Specialty Products | Operating Segments
Segment Reporting, Disclosure of Other Information about Entity's Reportable Segments [Abstract]
Net sales	75,808	73,355	70,126
Industrial Products | Operating Segments
Segment Reporting, Disclosure of Other Information about Entity's Reportable Segments [Abstract]
Net sales	$ 50,941	$ 47,951	$ 24,825