Inventories (Details) $ in Thousands, bu in Millions	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($) bu	Jun. 30, 2018 USD ($) bu
Inventory, Net [Abstract]
Grain and other agricultural products	$ 603,318	$ 527,471	$ 385,118
Frac sand and propane	9,287	0	0
Ethanol and co-products	26,185	11,918	22,828
Plant nutrients and cob products	109,156	145,693	82,230
Railcar repair parts	5,695	5,722	5,435
Total inventories	$ 753,641	$ 690,804	$ 495,611
Bushels of grain held in storage for others and excluded from inventory calculations | bu		0.1	1.3