Summary of Significant Accounting Policies - Purchase and Sales Contracts Outstanding (Details)	Nov. 30, 2013 Barrels Bushels T	Aug. 31, 2013 t Barrels Bushels	Nov. 30, 2012 Bushels t Barrels
Purchase Contracts
Purchase and Sales Contracts [Line Items]
Grain and oilseed - bushels	671,414,000	521,979,000	674,866,000
Energy products - barrels	27,352,000	12,626,000	7,483,000
Soy products - tons	12,000	24,000	21,000
Crop nutrients - tons	986,000	968,000	1,270,000
Ocean and barge freight - metric tons	2,054,000	1,225,000	1,288,000
Derivative, Number of Units, Cargo and Freight Rail Contract	201,000	220,000	164,000
Derivative, Number of Units, Livestock			2,680,000
Sales Contracts
Purchase and Sales Contracts [Line Items]
Grain and oilseed - bushels	944,517,000	806,295,000	1,018,510,000
Energy products - barrels	33,110,000	21,312,000	19,817,000
Soy products - tons	885,000	847,000	360,000
Crop nutrients - tons	1,204,000	1,050,000	1,428,000
Ocean and barge freight - metric tons	295,000	151,000	210,000
Derivative, Number of Units, Cargo and Freight Rail Contract	48,000	43,000	30,000
Derivative, Number of Units, Livestock	12,480,000	17,280,000	3,280,000