Derivative Financial Instruments and Hedging Activities Purchase and Sale Contracts (Details) - Not Designated as Hedging Instrument [Member] t in Thousands, rail_car in Thousands, T in Thousands, MMBtu in Thousands, Bushels in Thousands, Barrels in Thousands	Nov. 30, 2016 rail_car T t Bushels Barrels MMBtu	Aug. 31, 2016 rail_car T t Bushels Barrels MMBtu
Grain and oilseed - bushels | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | Bushels	698,853	774,279
Grain and oilseed - bushels | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | Bushels	992,878	995,396
Energy products - barrels | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | Barrels	12,666	14,740
Energy products - barrels | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | Barrels	5,767	6,470
Processed grain and oilseed - tons | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	502	541
Processed grain and oilseed - tons | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	1,958	2,060
Crop nutrients - tons | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	65	108
Crop nutrients - tons | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	209	135
Ocean and barge freight - metric tons | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | t	6,571	4,406
Ocean and barge freight - metric tons | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | t	1,422	877
Rail freight - rail cars | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | rail_car	195	205
Rail freight - rail cars | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | rail_car	77	79
Natural gas - MMBtu | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | MMBtu	3,706	3,550
Natural gas - MMBtu | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount | MMBtu	50	300