Derivative Financial Instruments and Hedging Activities Purchase and Sale Contracts (Details) (Forward Contracts [Member])	May 31, 2014 Bushels	Aug. 31, 2013 Bushels	May 31, 2013 Bushels
Grain and oilseed - bushels | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	717,181,000	521,979,000	519,293,000
Grain and oilseed - bushels | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	969,100,000	806,295,000	806,244,000
Energy products - barrels | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	20,517,000	12,626,000	13,833,000
Energy products - barrels | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	35,676,000	21,312,000	20,125,000
Soy products - tons | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	33,000	24,000	70,000
Soy products - tons | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	962,000	847,000	325,000
Crop nutrients - tons | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	1,077,000	968,000	675,000
Crop nutrients - tons | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	1,194,000	1,050,000	778,000
Ocean and barge freight - tons | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	1,148,000	1,225,000	888,000
Ocean and barge freight - tons | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	290,000	151,000	130,000
Rail freight - rail cars | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	339,000	220,000	242,000
Rail freight - rail cars | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	159,000	43,000	39,000
Livestock - pounds | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	0	0	7,760,000
Livestock - pounds | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	47,800,000	17,280,000	0