Investments - Schedule of Investments (Details) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2012	Aug. 31, 2011
Schedule of Equity Method Investments [Line Items]
Investments total	$ 673,388	$ 595,979
Ventura Foods, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	292,393	278,865
Horizon Milling, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	78,372	79,770
TEMCO, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	60,734	47,337
Horizon Milling G.P.
Schedule of Equity Method Investments [Line Items]
Equity method investments	16,727	20,445
Land O'Lakes, Inc.
Schedule of Equity Method Investments [Line Items]
Cost method investments	58,382	53,147
Ag Processing Inc.
Schedule of Equity Method Investments [Line Items]
Cost method investments	19,577	17,876
Other
Schedule of Equity Method Investments [Line Items]
Equity and cost method investments	$ 147,203	$ 98,539