Notes Payable and Long-Term Debt - Footnote Narrative (Details) (USD $)	Nov. 30, 2012	Aug. 31, 2012	Nov. 30, 2011
Debt Instrument [Line Items]
Notes payable	$ 876,846,000	$ 803,622,000	$ 645,515,000
Notes payable | Line of credit | Revolving credit facility
Debt Instrument [Line Items]
Notes payable	274,960,000	269,783,000	124,498,000
Three-year revolving facilities | Line of credit | Revolving credit facility
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity	1,250,000,000
Three-year and five-year revolving facilities | Line of credit | Revolving credit facility
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity	2,500,000,000
CHS Capital notes payable | Notes payable, other payables
Debt Instrument [Line Items]
Notes payable	$ 601,886,000	$ 533,839,000	$ 521,017,000