Segment Reporting - By Segment (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net sales	$ 189,349		$ 196,934	$ 565,801	$ 609,099
EBITDA	24,444		25,872	76,482	78,253
Depreciation and amortization	11,130		10,864	31,776	33,317
Food, Health and Nutrition
Segment Reporting Information [Line Items]
Net sales	105,174		115,132	326,783	367,159
EBITDA	14,791		14,563	48,758	48,494
Depreciation and amortization	6,959		7,142	20,128	21,677
Industrial Specialties
Segment Reporting Information [Line Items]
Net sales	73,141		65,667	204,064	195,767
EBITDA	8,861		8,885	23,891	26,772
Depreciation and amortization	3,768		3,153	10,714	10,257
Other
Segment Reporting Information [Line Items]
Net sales	11,034		16,135	34,954	46,173
EBITDA	792		2,424	3,833	2,987
Depreciation and amortization	$ 403		$ 569	$ 934	$ 1,383
Reconciling adjustment | Food, Health and Nutrition
Segment Reporting Information [Line Items]
EBITDA		$ 1,000
Reconciling adjustment | Industrial Specialties
Segment Reporting Information [Line Items]
EBITDA		400
Reconciling adjustment | Other
Segment Reporting Information [Line Items]
EBITDA		$ (1,400)