Inventories - Schedule of Inventories (Details) - USD ($) $ in Thousands	May 31, 2018	Aug. 31, 2017
Inventory Disclosure [Abstract]
Grain and oilseed	$ 1,436,568	$ 1,145,285
Energy	663,111	755,886
Crop nutrients	199,246	248,699
Feed and farm supplies	479,621	353,130
Processed grain and oilseed	152,465	49,723
Other	9,896	23,862
Total inventories	$ 2,940,907	$ 2,576,585