Fair Value Measurement (Tables)

6 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

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

The following table presents our financial assets and financial liabilities that are measured at fair value on a recurring basis for each of the fair value hierarchy levels, including both current and noncurrent portions, as of March 31, 2013, September 30, 2012 and March 31, 2012:

	Asset (Liability)
	Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)			Significant Other Observable Inputs (Level 2)			Unobservable Inputs (Level 3)		Total
March 31, 2013:
Assets:
Derivative financial instruments:
Commodity contracts	$	7.9		$	5.7		$	—	$	13.6
Foreign currency contracts	$	—		$	1.5		$	—	$	1.5
Interest rate contracts	$	—		$	4.2		$	—	$	4.2
Liabilities:
Derivative financial instruments:
Commodity contracts	$	(2.7	)	$	(12.6	)	$	—	$	(15.3	)
Foreign currency contracts	$	—		$	(0.5	)	$	—	$	(0.5	)
Interest rate contracts	$	—		$	(60.5	)	$	—	$	(60.5	)
September 30, 2012:
Assets:
Derivative financial instruments:
Commodity contracts	$	8.6		$	4.5		$	—	$	13.1
Foreign currency contracts	$	—		$	1.8		$	—	$	1.8
Liabilities:
Derivative financial instruments:
Commodity contracts	$	(7.8	)	$	(53.2	)	$	—	$	(61.0	)
Interest rate contracts	$	—		$	(71.9	)	$	—	$	(71.9	)
March 31, 2012:
Assets:
Derivative financial instruments:
Commodity contracts	$	9.8		$	1.2		$	—	$	11.0
Foreign currency contracts	$	—		$	3.1		$	—	$	3.1
Liabilities:
Derivative financial instruments:
Commodity contracts	$	(41.1	)	$	(42.2	)	$	—	$	(83.3	)
Interest rate contracts	$	—		$	(53.2	)	$	—	$	(53.2	)