Derivatives and Risk Management (Details 6) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2011	Aug. 31, 2011
Derivatives, Fair Value [Line Items]
Derivative assets (other current assets and other assets)	$ 49,465	$ 52,858
Commodity [Member]
Derivatives, Fair Value [Line Items]
Derivative assets (other current assets and other assets) Designated as Hedging Instrument, Fair Value	62	17
Derivative assets (other current assets and other assets) Not Designated as Hedging Instrument, Fair Value	1,918	2,329
Foreign Exchange [Member]
Derivatives, Fair Value [Line Items]
Derivative assets (other current assets and other assets) Designated as Hedging Instrument, Fair Value	1,176	893
Derivative assets (other current assets and other assets) Not Designated as Hedging Instrument, Fair Value	680	970
Interest Rate [Member]
Derivatives, Fair Value [Line Items]
Derivative assets (other current assets and other assets) Designated as Hedging Instrument, Fair Value	17,403	19,134
Long Term interest Rate [Member]
Derivatives, Fair Value [Line Items]
Derivative assets (other current assets and other assets) Designated as Hedging Instrument, Fair Value	$ 28,226	$ 29,515