Fair Value Measurement (Tables)

12 Months Ended

Sep. 30, 2011

Fair Value Measurements [Abstract]

Financial assets and financial liabilities at fair value on a recurring basis

	Asset (Liability)
	Quoted Prices in
	Active Markets		Significant
	for Identical		Other
	Assets and		Observable			Unobservable
	Liabilities		Inputs			Inputs
	(Level 1)		(Level 2)			(Level 3)		Total
September 30, 2011:
Assets:
Derivative financial instruments:
Commodity contracts	$	—	$	864		$	—	$	864
Liabilities:
Derivative financial instruments:
Commodity contracts	$	—	$	(7,248	)	$	—	$	(7,248	)
September 30, 2010:
Assets:
Derivative financial instruments:
Commodity contracts	$	—	$	8,025		$	—	$	8,025