Derivatives and Risk Management (Details 7) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2011	Aug. 31, 2011
Derivatives, Fair Value [Line Items]
Derivative liabilities (accrued expenses, other payables and long-term liabilities)	$ 7,736	$ 5,688
Commodity [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities (accrued expenses, other payables and long-term liabilities) Not Designated as Hedging Instrument, Fair Value	3,268	2,625
Foreign Exchange [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities (accrued expenses, other payables and long-term liabilities) Designated as Hedging Instrument, Fair Value	1,901	805
Derivative liabilities (accrued expenses, other payables and long-term liabilities) Not Designated as Hedging Instrument, Fair Value	$ 2,567	$ 2,258