Fair Value Measurement (Tables)

3 Months Ended

Dec. 31, 2012

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 December 31, 2012, September 30, 2012 and December 31, 2011:

	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
December 31, 2012:
Assets:
Derivative financial instruments:
Commodity contracts	$	0.7		$	6.5		$	—	$	7.2
Interest rate contracts	$	—		$	4.2		$	—	$	4.2
Liabilities:
Derivative financial instruments:
Commodity contracts	$	(9.3	)	$	(37.6	)	$	—	$	(46.9	)
Foreign currency contracts	$	—		$	(2.4	)	$	—	$	(2.4	)
Interest rate contracts	$	—		$	(71.8	)	$	—	$	(71.8	)
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	)
December 31, 2011:
Assets:
Derivative financial instruments:
Commodity contracts	$	7.4		$	2.0		$	—	$	9.4
Foreign currency contracts	$	—		$	7.0		$	—	$	7.0
Liabilities:
Derivative financial instruments:
Commodity contracts	$	(43.9	)	$	(34.6	)	$	—	$	(78.5	)
Interest rate contracts	$	—		$	(52.4	)	$	—	$	(52.4	)