Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Sales and merchandising revenues	$ 1,566,964	$ 1,315,834	$ 2,838,934	$ 2,452,967
Inter-segment sales	4,962	6,039	14,094	10,302
Interest expense	4,855	5,380	11,259	10,710
Equity in earnings (loss) of affiliates	10,010	5,096	17,814	9,379
Other income (expense), net	1,292	2,671	4,018	5,917
Income (loss) before income taxes	48,212	45,827	69,603	73,796
Identifiable assets	1,820,981	1,794,774	1,820,981	1,794,774	2,182,304
Grain
Segment Reporting Information [Line Items]
Sales and merchandising revenues	891,350	718,911	1,727,845	1,418,772
Inter-segment sales	1	0	333	1
Interest expense	2,474	2,687	6,323	5,939
Equity in earnings (loss) of affiliates	5,027	7,505	12,937	13,457
Other income (expense), net	(349)	489	222	1,316
Income (loss) before income taxes	2,053	15,277	10,352	34,712
Identifiable assets	794,913	844,526	794,913	844,526	1,076,986
Ethanol
Segment Reporting Information [Line Items]
Sales and merchandising revenues	222,240	167,758	421,549	318,428
Interest expense	280	185	606	209
Equity in earnings (loss) of affiliates	4,983	(2,410)	4,877	(4,081)
Other income (expense), net	199	20	430	36
Income (loss) before income taxes	10,601	(2,105)	13,080	(1,984)
Identifiable assets	207,977	212,094	207,977	212,094	206,975
Plant Nutrient
Segment Reporting Information [Line Items]
Sales and merchandising revenues	330,339	308,797	442,241	484,157
Inter-segment sales	4,015	5,334	11,712	8,417
Interest expense	797	632	1,715	1,342
Equity in earnings (loss) of affiliates	0	1	0	3
Other income (expense), net	164	1,010	139	1,128
Income (loss) before income taxes	23,240	27,953	22,678	33,781
Identifiable assets	240,192	214,617	240,192	214,617	257,980
Rail
Segment Reporting Information [Line Items]
Sales and merchandising revenues	38,601	32,046	84,965	67,905
Inter-segment sales	105	208	209	411
Interest expense	1,429	1,156	2,942	2,334
Other income (expense), net	702	824	1,648	1,600
Income (loss) before income taxes	9,680	7,199	24,254	15,217
Identifiable assets	298,525	310,651	298,525	310,651	289,467
Turf and Specialty
Segment Reporting Information [Line Items]
Sales and merchandising revenues	43,144	43,845	90,331	88,972
Inter-segment sales	841	497	1,840	1,473
Interest expense	346	312	748	668
Other income (expense), net	175	289	450	490
Income (loss) before income taxes	2,195	2,753	6,196	4,955
Identifiable assets	73,343	66,580	73,343	66,580	82,683
Retail
Segment Reporting Information [Line Items]
Sales and merchandising revenues	41,290	44,477	72,003	74,733
Interest expense	152	157	367	353
Other income (expense), net	100	155	214	279
Income (loss) before income taxes	1,539	1,428	(1,630)	(1,321)
Identifiable assets	50,313	56,986	50,313	56,986	51,772
Other
Segment Reporting Information [Line Items]
Interest expense	(623)	251	(1,442)	(135)
Other income (expense), net	301	(116)	915	1,068
Income (loss) before income taxes	(2,289)	(5,950)	(6,254)	(10,157)
Identifiable assets	155,718	89,320	155,718	89,320	216,441
Noncontrolling Interests
Segment Reporting Information [Line Items]
Income (loss) before income taxes	$ 1,193	$ (728)	$ 927	$ (1,407)