Revenue (Disaggregation of Revenues) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Total	$ 193,650
Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	75,078
Primary nutrients
Disaggregation of Revenue [Line Items]
Total	53,219
Service
Disaggregation of Revenue [Line Items]
Total	15,289
Co-products
Disaggregation of Revenue [Line Items]
Total	26,646
Other
Disaggregation of Revenue [Line Items]
Total	23,418
Grain
Disaggregation of Revenue [Line Items]
Total	4,628
Grain | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	0
Grain | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	0
Grain | Service
Disaggregation of Revenue [Line Items]
Total	4,418
Grain | Co-products
Disaggregation of Revenue [Line Items]
Total	0
Grain | Other
Disaggregation of Revenue [Line Items]
Total	210
Ethanol
Disaggregation of Revenue [Line Items]
Total	29,191
Ethanol | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	0
Ethanol | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	0
Ethanol | Service
Disaggregation of Revenue [Line Items]
Total	2,545
Ethanol | Co-products
Disaggregation of Revenue [Line Items]
Total	26,646
Ethanol | Other
Disaggregation of Revenue [Line Items]
Total	0
Plant Nutrient
Disaggregation of Revenue [Line Items]
Total	135,617
Plant Nutrient | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	75,078
Plant Nutrient | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	53,219
Plant Nutrient | Service
Disaggregation of Revenue [Line Items]
Total	209
Plant Nutrient | Co-products
Disaggregation of Revenue [Line Items]
Total	0
Plant Nutrient | Other
Disaggregation of Revenue [Line Items]
Total	7,111
Rail
Disaggregation of Revenue [Line Items]
Total	24,214
Rail | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	0
Rail | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	0
Rail | Service
Disaggregation of Revenue [Line Items]
Total	8,117
Rail | Co-products
Disaggregation of Revenue [Line Items]
Total	0
Rail | Other
Disaggregation of Revenue [Line Items]
Total	$ 16,097