Inventories (Details) $ in Thousands, bu in Millions	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) bu	Mar. 31, 2018 USD ($) bu
Inventory, Net [Abstract]
Grain and other agricultural products	$ 812,361	$ 527,471	$ 541,272
Frac sand and propane	8,172	0	0
Ethanol and co-products	16,302	11,918	14,320
Plant nutrients and cob products	183,886	145,693	170,748
Railcar repair parts	5,744	5,722	5,289
Total inventories	$ 1,026,465	$ 690,804	$ 731,629
Bushels of grain held in storage for others and excluded from inventory calculations | bu		0.7	1.9