Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Net sales	$ 88,252	$ 85,753	$ 176,208	$ 172,922
Distillery products
Disaggregation of Revenue [Line Items]
Net sales	72,652	70,699	147,029	144,648
Distillery products | Products transferred at a point in time
Disaggregation of Revenue [Line Items]
Net sales	69,725	68,128	141,227	139,454
Distillery products | Services transferred over time
Disaggregation of Revenue [Line Items]
Net sales	2,927	2,571		5,194
Ingredient solutions
Disaggregation of Revenue [Line Items]
Net sales	15,600	15,054	29,179	28,274
Ingredient solutions | Products transferred at a point in time
Disaggregation of Revenue [Line Items]
Net sales	15,600	15,054	29,179	28,274
Food grade alcohol | Distillery products
Disaggregation of Revenue [Line Items]
Net sales	61,495	61,629	124,910	126,391
Premium beverage alcohol | Distillery products
Disaggregation of Revenue [Line Items]
Net sales	42,200	42,287	86,271	87,926
Industrial alcohol | Distillery products
Disaggregation of Revenue [Line Items]
Net sales	19,295	19,342	38,639	38,465
Fuel grade alcohol | Distillery products
Disaggregation of Revenue [Line Items]
Net sales	1,567	1,767	3,430	3,409
Distillers feed and related co-products | Distillery products
Disaggregation of Revenue [Line Items]
Net sales	6,663	4,732	12,887	9,654
Warehouse services | Distillery products
Disaggregation of Revenue [Line Items]
Net sales	2,927	2,571	5,802	5,194
Specialty wheat starches | Ingredient solutions
Disaggregation of Revenue [Line Items]
Net sales	7,339	7,411	14,140	13,818
Specialty wheat proteins | Ingredient solutions
Disaggregation of Revenue [Line Items]
Net sales	6,008	5,224	10,744	9,603
Commodity wheat starch | Ingredient solutions
Disaggregation of Revenue [Line Items]
Net sales	2,090	2,266	4,132	4,354
Commodity wheat protein | Ingredient solutions
Disaggregation of Revenue [Line Items]
Net sales	$ 163	$ 153	$ 163	$ 499