Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Sales and merchandising revenues		$ 1,183,473	$ 909,093	$ 1,187,704	$ 918,225	$ 1,271,768	$ 952,927	$ 1,312,082	$ 1,003,294	$ 4,198,495	$ 4,540,071	$ 5,604,574
Inter-segment sales										5,447	6,159	882
Interest expense (income)										20,072	21,760	20,860
Equity in earnings of affiliates, net										31,924	96,523	68,705
Other income, net										46,472	31,125	14,876
Income (loss) before income taxes										(11,564)	184,146	149,513
Identifiable assets		2,359,101				2,364,692				2,359,101	2,364,692
Capital expenditures										72,469	59,675	46,786
Acquisition of businesses, net of cash acquired and investments in affiliates										129,299	55,795	64,501
Depreciation and amortization										78,456	62,005	55,307
Grain
Segment Reporting Information [Line Items]
Sales and merchandising revenues										2,483,643	2,682,038	3,617,943
Inter-segment sales										3,573	5,066	1
Interest expense (income)										5,778	8,785	9,567
Equity in earnings of affiliates, net										14,703	27,643	33,122
Other income, net										26,229	21,450	2,120
Income (loss) before income taxes										(9,446)	58,136	46,805
Identifiable assets		1,010,810				1,137,437				1,010,810	1,137,437
Capital expenditures										26,862	20,958	8,535
Acquisition of businesses, net of cash acquired and investments in affiliates										0	40,206	51,544
Depreciation and amortization										19,240	16,547	15,620
Ethanol
Segment Reporting Information [Line Items]
Sales and merchandising revenues										556,188	765,939	831,965
Interest expense (income)										70	255	1,038
Equity in earnings of affiliates, net										17,221	68,880	35,583
Other income, net										377	223	399
Income (loss) before income taxes										28,503	92,257	50,600
Identifiable assets		183,080				197,888				183,080	197,888
Capital expenditures										7,223	2,256	4,052
Acquisition of businesses, net of cash acquired and investments in affiliates										0	0	0
Depreciation and amortization										5,865	5,700	5,909
Plant Nutrient
Segment Reporting Information [Line Items]
Sales and merchandising revenues										848,338	802,333	849,166
Inter-segment sales										682	627	454
Interest expense (income)										7,243	5,278	4,549
Other income, net										3,046	4,372	1,783
Income (loss) before income taxes										121	24,514	32,019
Identifiable assets		531,753				433,013				531,753	433,013
Capital expenditures										14,384	24,491	23,657
Acquisition of businesses, net of cash acquired and investments in affiliates										128,549	15,489	4,103
Depreciation and amortization										25,179	19,624	17,213
Rail
Segment Reporting Information [Line Items]
Sales and merchandising revenues										170,848	148,954	164,794
Inter-segment sales										1,192	466	427
Interest expense (income)										7,006	7,247	5,544
Other income, net										15,935	3,094	7,666
Income (loss) before income taxes										50,681	31,445	42,785
Identifiable assets		405,702				365,531				405,702	365,531
Capital expenditures										2,990	2,332	4,135
Acquisition of businesses, net of cash acquired and investments in affiliates										0	0	7,804
Depreciation and amortization										18,450	13,262	12,031
Retail
Segment Reporting Information [Line Items]
Sales and merchandising revenues										139,478	140,807	140,706
Interest expense (income)										356	666	689
Other income, net										557	955	501
Income (loss) before income taxes										(455)	(620)	(7,534)
Identifiable assets		44,135				44,536				44,135	44,536
Capital expenditures										1,005	1,190	2,944
Depreciation and amortization										2,510	2,668	3,119
Other Segments
Segment Reporting Information [Line Items]
Interest expense (income)										(381)	(471)	(527)
Other income, net										328	1,031	2,407
Income (loss) before income taxes	[1]									(82,713)	(34,505)	(20,925)
Identifiable assets		$ 183,621				$ 186,287				183,621	186,287
Capital expenditures										20,005	8,448	3,463
Acquisition of businesses, net of cash acquired and investments in affiliates										750	100	1,050
Depreciation and amortization										7,212	4,204	1,415
Non-controlling interests
Segment Reporting Information [Line Items]
Income (loss) before income taxes										$ 1,745	$ 12,919	$ 5,763

[1] includes pension settlement charges in 2015