Investments - Narrative (Details) (USD $)	12 Months Ended
	Aug. 31, 2013	Aug. 31, 2012	Aug. 31, 2011	May 31, 2013
Schedule of Equity Method Investments [Line Items]
Expected ownership of future joint venture				12.00%
Expected borrowings of future joint venture				$ 600,000,000
Proceeds from Equity Method Investment, Dividends or Distributions	62,761,000	75,468,000	137,766,000
Joint venture, realized gain (loss) on disposal		800,000	9,000,000
Ventura Foods, LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Equity value exceeding carrying value	12,900,000
Multigrain AG
Schedule of Equity Method Investments [Line Items]
Ownership percentage			45.00%
Joint venture, net sales proceeds			225,000,000
Joint venture, realized gain (loss) on disposal			119,700,000
Agrillance LLC
Schedule of Equity Method Investments [Line Items]
Defined benefit plan, transfer of liabilities in	84,500,000	84,500,000
Ownership percentage	50.00%
Payments to acquire equity method investments	45,400,000
Defined benefit plan, transfer of assets in	97,200,000	97,200,000
Agrillance LLC | Transfer of Pension Plan Assets And Liabilities
Schedule of Equity Method Investments [Line Items]
Proceeds from joint venture, dividends or distributions, return of capital	12,700,000	12,700,000
Agrillance LLC | Land O' Lakes
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Agriliance [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Equity Method Investment, Dividends or Distributions			$ 28,000,000
TEMCO, LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Long-term supply commitment, term	25 years
TEMCO, LLC | Cargill, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%