Fair Value Measurements

6 Months Ended

Mar. 31, 2012

Fair Value Measurements [Abstract]

Fair Value Measurements

13. Fair Value Measurements

Derivative Financial Instruments

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

	Asset (Liability)
	Quoted Prices
	in Active			Significant
	Markets for			Other
	Identical Assets			Observable			Unobservable
	and Liabilities			Inputs			Inputs
	(Level 1)			(Level 2)			(Level 3)		Total
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	)
September 30, 2011:
Assets:
Derivative financial instruments:
Commodity contracts	$	3.5		$	3.3		$	—	$	6.8
Foreign currency contracts	$	—		$	5.3		$	—	$	5.3
Liabilities:
Derivative financial instruments:
Commodity contracts	$	(28.1	)	$	(16.1	)	$	—	$	(44.2	)
Foreign currency contracts	$	—		$	(3.3	)	$	—	$	(3.3	)
Interest rate contracts	$	—		$	(44.4	)	$	—	$	(44.4	)
March 31, 2011:
Assets:
Derivative financial instruments:
Commodity contracts	$	2.6		$	12.1		$	—	$	14.7
Foreign currency contracts	$	—		$	0.3		$	—	$	0.3
Interest rate contracts	$	—		$	13.0		$	—	$	13.0
Liabilities:
Derivative financial instruments:
Commodity contracts	$	(10.6	)	$	(9.8	)	$	—	$	(20.4	)
Foreign currency contracts	$	—		$	(4.0	)	$	—	$	(4.0	)
Interest rate contracts	$	—		$	(0.2	)	$	—	$	(0.2	)

The fair values of our Level 1 exchange-traded commodity futures and option contracts and non exchange-traded commodity futures and forward contracts are based upon actively-quoted market prices for identical assets and liabilities. The remainder of our derivative financial instruments are designated as Level 2. The fair values of certain non-exchange traded commodity derivatives are based upon indicative price quotations available through brokers, industry price publications or recent market transactions and related market indicators. For commodity option contracts not traded on an exchange, we use a Black Scholes option pricing model that considers time value and volatility of the underlying commodity. The fair values of interest rate contracts and foreign currency contracts are based upon third-party quotes or indicative values based on recent market transactions. There were no transfers between Level 1 and Level 2 during the periods presented.

Other Financial Instruments

The carrying amounts of other financial instruments included in current assets and current liabilities (excluding current maturities of long-term debt) approximate their fair values because of their short-term nature. At March 31, 2012, the carrying amount and estimated fair value of our long-term debt (including current maturities) were $3,611.6 and $3,738.6, respectively. At March 31, 2011, the carrying amount and estimated fair value of our long-term debt (including current maturities) were $2,066.0 and $2,159.9, respectively. We estimate the fair value of long-term debt by using current market rates and by discounting future cash flows using rates available for similar type debt (Level 2).

Financial instruments other than derivative financial instruments, such as our short-term investments and trade accounts receivable, could expose us to concentrations of credit risk. We limit our credit risk from short-term investments by investing only in investment-grade commercial paper, money market mutual funds, securities guaranteed by the U.S. Government or its agencies and FDIC insured bank deposits. The credit risk from trade accounts receivable is limited because we have a large customer base which extends across many different U.S. markets and several foreign countries. For information regarding concentrations of credit risk associated with our derivative financial instruments, see Note 14.