Revenue (Disaggregation of Revenues) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Total	$ 898,885
Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	260,821
Primary nutrients
Disaggregation of Revenue [Line Items]
Total	399,566
Services
Disaggregation of Revenue [Line Items]
Total	65,042
Co-products
Disaggregation of Revenue [Line Items]
Total	114,489
Other
Disaggregation of Revenue [Line Items]
Total	58,967
Grain
Disaggregation of Revenue [Line Items]
Total	15,701
Grain | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	0
Grain | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	0
Grain | Services
Disaggregation of Revenue [Line Items]
Total	14,666
Grain | Co-products
Disaggregation of Revenue [Line Items]
Total	0
Grain | Other
Disaggregation of Revenue [Line Items]
Total	1,035
Ethanol
Disaggregation of Revenue [Line Items]
Total	125,275
Ethanol | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	0
Ethanol | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	0
Ethanol | Services
Disaggregation of Revenue [Line Items]
Total	10,786
Ethanol | Co-products
Disaggregation of Revenue [Line Items]
Total	114,489
Ethanol | Other
Disaggregation of Revenue [Line Items]
Total	0
Plant Nutrient
Disaggregation of Revenue [Line Items]
Total	690,536
Plant Nutrient | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	260,821
Plant Nutrient | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	399,566
Plant Nutrient | Services
Disaggregation of Revenue [Line Items]
Total	4,411
Plant Nutrient | Co-products
Disaggregation of Revenue [Line Items]
Total	0
Plant Nutrient | Other
Disaggregation of Revenue [Line Items]
Total	25,738
Rail
Disaggregation of Revenue [Line Items]
Total	67,373
Rail | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	0
Rail | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	0
Rail | Services
Disaggregation of Revenue [Line Items]
Total	35,179
Rail | Co-products
Disaggregation of Revenue [Line Items]
Total	0
Rail | Other
Disaggregation of Revenue [Line Items]
Total	$ 32,194