Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Sales and merchandising revenues	$ 635,739	$ 852,016
Income (loss) before income taxes	(2,292)	(5,570)
Total assets	2,363,528	2,161,753	$ 2,162,354
Operating Segments | Grain
Segment Reporting Information [Line Items]
Sales and merchandising revenues	276,852	478,528
Income (loss) before income taxes	(30)	(5,073)
Total assets	1,031,150	884,870	948,871
Operating Segments | Ethanol
Segment Reporting Information [Line Items]
Sales and merchandising revenues	172,838	154,153
Income (loss) before income taxes	1,839	1,716
Total assets	210,169	170,020	180,173
Operating Segments | Plant Nutrient
Segment Reporting Information [Line Items]
Sales and merchandising revenues	135,617	146,587
Income (loss) before income taxes	1,091	6,672
Total assets	455,148	512,744	379,309
Operating Segments | Rail
Segment Reporting Information [Line Items]
Sales and merchandising revenues	50,432	40,390
Income (loss) before income taxes	3,969	6,078
Total assets	530,994	415,801	490,448
Operating Segments | Retail
Segment Reporting Information [Line Items]
Sales and merchandising revenues	0	32,358
Segment Reconciling Items
Segment Reporting Information [Line Items]
Sales and merchandising revenues	864	529
Segment Reconciling Items | Grain
Segment Reporting Information [Line Items]
Sales and merchandising revenues	531	66
Segment Reconciling Items | Plant Nutrient
Segment Reporting Information [Line Items]
Sales and merchandising revenues	0	171
Segment Reconciling Items | Rail
Segment Reporting Information [Line Items]
Sales and merchandising revenues	333	292
Other
Segment Reporting Information [Line Items]
Income (loss) before income taxes	(8,879)	(15,017)
Total assets	136,067	178,318	$ 163,553
Noncontrolling interests
Segment Reporting Information [Line Items]
Income (loss) before income taxes	$ (282)	$ 54