Revenue (Disaggregation of Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total	$ 347,502	$ 315,172
Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	73,231	72,338
Primary nutrients
Disaggregation of Revenue [Line Items]
Total	45,690	53,516
Service
Disaggregation of Revenue [Line Items]
Total	10,604	14,370
Ethanol products and co-products
Disaggregation of Revenue [Line Items]
Total	154,863	84,230
Frac sand and propane
Disaggregation of Revenue [Line Items]
Total	49,875	80,463
Other
Disaggregation of Revenue [Line Items]
Total	13,239	10,255
Trade
Disaggregation of Revenue [Line Items]
Total	108,715	149,568
Trade | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	0	3,938
Trade | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	0	427
Trade | Service
Disaggregation of Revenue [Line Items]
Total	1,686	825
Trade | Ethanol products and co-products
Disaggregation of Revenue [Line Items]
Total	53,165	62,758
Trade | Frac sand and propane
Disaggregation of Revenue [Line Items]
Total	49,875	80,463
Trade | Other
Disaggregation of Revenue [Line Items]
Total	3,989	1,157
Ethanol
Disaggregation of Revenue [Line Items]
Total	102,314	24,908
Ethanol | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	0	0
Ethanol | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	0	0
Ethanol | Service
Disaggregation of Revenue [Line Items]
Total	0	3,436
Ethanol | Ethanol products and co-products
Disaggregation of Revenue [Line Items]
Total	101,698	21,472
Ethanol | Frac sand and propane
Disaggregation of Revenue [Line Items]
Total	0	0
Ethanol | Other
Disaggregation of Revenue [Line Items]
Total	616	0
Plant Nutrient
Disaggregation of Revenue [Line Items]
Total	124,913	128,525
Plant Nutrient | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	73,231	68,400
Plant Nutrient | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	45,690	53,089
Plant Nutrient | Service
Disaggregation of Revenue [Line Items]
Total	182	162
Plant Nutrient | Ethanol products and co-products
Disaggregation of Revenue [Line Items]
Total	0	0
Plant Nutrient | Frac sand and propane
Disaggregation of Revenue [Line Items]
Total	0	0
Plant Nutrient | Other
Disaggregation of Revenue [Line Items]
Total	5,810	6,874
Rail
Disaggregation of Revenue [Line Items]
Total	11,560	12,171
Rail | Specialty nutrients
Disaggregation of Revenue [Line Items]
Total	0	0
Rail | Primary nutrients
Disaggregation of Revenue [Line Items]
Total	0	0
Rail | Service
Disaggregation of Revenue [Line Items]
Total	8,736	9,947
Rail | Ethanol products and co-products
Disaggregation of Revenue [Line Items]
Total	0	0
Rail | Frac sand and propane
Disaggregation of Revenue [Line Items]
Total	0	0
Rail | Other
Disaggregation of Revenue [Line Items]
Total	$ 2,824	$ 2,224