Inventories (Details) $ in Thousands, bu in Millions	Jun. 30, 2015 USD ($) bu	Dec. 31, 2014 USD ($) bu	Jun. 30, 2014 USD ($) bu
Inventory, Net [Abstract]
Grain	$ 327,480	$ 570,916	$ 290,595
Ethanol and by-products	12,802	13,154	16,798
Plant nutrients and cob products	136,472	181,136	95,122
Retail merchandise	25,415	23,810	25,180
Railcar repair parts	6,050	6,431	5,107
Other	189	208	194
Total inventories	$ 508,408	$ 795,655	$ 432,996
Bushels of grain held in storage and excluded from inventory calculations | bu	1.2	3.1	3.7