Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Sales and merchandising revenues		$ 1,113,055	$ 859,612	$ 1,064,244	$ 887,879	$ 1,183,473	$ 909,093	$ 1,187,704	$ 918,225	$ 3,924,790	$ 4,198,495	$ 4,540,071
Interest expense (income)										21,119	20,072	21,760
Equity in earnings of affiliates, net										9,721	31,924	96,523
Other income, net										14,775	46,472	31,125
Income (loss) before income taxes										21,381	(11,564)	184,146
Identifiable assets		2,232,849				2,359,101				2,232,849	2,359,101
Capital expenditures										77,740	72,469	59,675
Acquisition of businesses, net of cash acquired and other investments										2,500	129,299	55,795
Depreciation and amortization										84,325	78,456	62,005
Grain
Segment Reporting Information [Line Items]
Depreciation and amortization										18,232	19,240	16,547
Ethanol
Segment Reporting Information [Line Items]
Depreciation and amortization										5,925	5,865	5,700
Plant Nutrient
Segment Reporting Information [Line Items]
Depreciation and amortization										28,663	25,179	19,624
Rail
Segment Reporting Information [Line Items]
Depreciation and amortization										20,082	18,450	13,262
Retail
Segment Reporting Information [Line Items]
Depreciation and amortization										2,452	2,510	2,668
Other Segments [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization										8,971	7,212	4,204
Operating Segments | Grain
Segment Reporting Information [Line Items]
Sales and merchandising revenues										2,357,171	2,483,643	2,682,038
Interest expense (income)										7,955	5,778	8,785
Equity in earnings of affiliates, net										(8,746)	14,703	27,643
Other income, net										5,472	26,229	21,450
Income (loss) before income taxes										(15,651)	(9,446)	58,136
Identifiable assets		961,114				1,010,810				961,114	1,010,810
Capital expenditures										21,428	26,862	20,958
Acquisition of businesses, net of cash acquired and other investments										0	0	40,206
Operating Segments | Ethanol
Segment Reporting Information [Line Items]
Sales and merchandising revenues										544,556	556,188	765,939
Interest expense (income)										35	70	255
Equity in earnings of affiliates, net										18,467	17,221	68,880
Other income, net										77	377	223
Income (loss) before income taxes										24,723	28,503	92,257
Identifiable assets		171,115				183,080				171,115	183,080
Capital expenditures										2,301	7,223	2,256
Acquisition of businesses, net of cash acquired and other investments										0	0	0
Operating Segments | Plant Nutrient
Segment Reporting Information [Line Items]
Sales and merchandising revenues										725,176	848,338	802,333
Interest expense (income)										6,448	7,243	5,278
Other income, net										3,716	3,046	4,372
Income (loss) before income taxes										14,176	121	24,514
Identifiable assets		484,455				531,753				484,455	531,753
Capital expenditures										15,153	14,384	24,491
Acquisition of businesses, net of cash acquired and other investments										0	128,549	15,489
Operating Segments | Rail
Segment Reporting Information [Line Items]
Sales and merchandising revenues										163,658	170,848	148,954
Interest expense (income)										6,461	7,006	7,247
Other income, net										2,218	15,935	3,094
Income (loss) before income taxes										32,428	50,681	31,445
Identifiable assets		398,446				405,702				398,446	405,702
Capital expenditures										4,345	2,990	2,332
Acquisition of businesses, net of cash acquired and other investments										0	0	0
Operating Segments | Retail
Segment Reporting Information [Line Items]
Sales and merchandising revenues										134,229	139,478	140,807
Interest expense (income)										496	356	666
Other income, net										507	557	955
Income (loss) before income taxes										(8,848)	(455)	(620)
Identifiable assets		31,257				44,135				31,257	44,135
Capital expenditures										436	1,005	1,190
Inter-Segments
Segment Reporting Information [Line Items]
Sales and merchandising revenues										3,507	5,447	6,159
Inter-Segments | Grain
Segment Reporting Information [Line Items]
Sales and merchandising revenues										1,638	3,573	5,066
Inter-Segments | Plant Nutrient
Segment Reporting Information [Line Items]
Sales and merchandising revenues										470	682	627
Inter-Segments | Rail
Segment Reporting Information [Line Items]
Sales and merchandising revenues										1,399	1,192	466
Other
Segment Reporting Information [Line Items]
Interest expense (income)										(276)	(381)	(471)
Other income, net										2,785	328	1,031
Income (loss) before income taxes	[1]									(28,323)	(82,713)	(34,505)
Identifiable assets		$ 186,462				$ 183,621				186,462	183,621
Capital expenditures										34,077	20,005	8,448
Acquisition of businesses, net of cash acquired and other investments										2,500	750	100
Non-controlling interest
Segment Reporting Information [Line Items]
Income (loss) before income taxes										$ 2,876	$ 1,745	$ 12,919

[1] includes pension settlement charges in 2015