SEGMENT INFORMATION - Business Segment Earnings Before Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Earnings before income taxes	$ 28,047	$ 27,907	$ 25,973	$ 24,490	$ 22,368	$ 24,436	$ 24,881	$ 24,793	$ 106,417	$ 96,478	$ 99,030
Interest and other expense									(4,730)	(6,075)	(8,070)
Other and Unallocated
Segment Reporting Information [Line Items]
Earnings before income taxes									(7,030)	(257)	7,202
Interest and other expense
Segment Reporting Information [Line Items]
Interest and other expense									(4,730)	(6,075)	(8,070)
Human Nutrition & Health | Operating Segments
Segment Reporting Information [Line Items]
Earnings before income taxes									61,397	48,429	48,037
Animal Nutrition & Health | Operating Segments
Segment Reporting Information [Line Items]
Earnings before income taxes									29,979	25,868	26,607
Specialty Products | Operating Segments
Segment Reporting Information [Line Items]
Earnings before income taxes									$ 26,801	$ 28,513	$ 25,254