Derivative Financial Instruments and Hedging Activities Purchase and Sale Contracts (Details) (Forward Contracts [Member])	Feb. 28, 2014 Bushels	Aug. 31, 2013 Bushels	Feb. 28, 2013 Bushels
Grain and oilseed - bushels | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	651,998,000	521,979,000	605,309,000
Grain and oilseed - bushels | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	1,009,946,000	806,295,000	906,758,000
Energy products - barrels | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	29,067,000	12,626,000	12,103,000
Energy products - barrels | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	32,897,000	21,312,000	21,575,000
Soy products - tons | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	16,000	24,000	32,000
Soy products - tons | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	784,000	847,000	333,000
Crop nutrients - tons | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	1,520,000	968,000	933,000
Crop nutrients - tons | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	2,535,000	1,050,000	125,000
Rail freight - rail cars | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	298,000	220,000	153,000
Rail freight - rail cars | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	157,000	43,000	41,000
Derivative number of units livestock [Member] | Long [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount			2,920,000
Derivative number of units livestock [Member] | Short [Member]
Purchase and Sales Contracts [Line Items]
Derivative, Nonmonetary Notional Amount	10,800,000	17,280,000	2,520,000