Fair Value Measurement (Details) (Fair Value, Measurements, Recurring [Member], USD $)	Mar. 31, 2013	Sep. 30, 2012	Mar. 31, 2012
Commodity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	$ 13,600,000	$ 13,100,000	$ 11,000,000
Derivative financial instruments, liabilities	(15,300,000)	(61,000,000)	(83,300,000)
Foreign currency contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	1,500,000	1,800,000	3,100,000
Derivative financial instruments, liabilities	(500,000)
Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	4,200,000
Derivative financial instruments, liabilities	(60,500,000)	(71,900,000)	(53,200,000)
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) [Member] | Commodity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	7,900,000	8,600,000	9,800,000
Derivative financial instruments, liabilities	(2,700,000)	(7,800,000)	(41,100,000)
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) [Member] | Foreign currency contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets
Derivative financial instruments, liabilities
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	0
Derivative financial instruments, liabilities
Significant Other Observable Inputs (Level 2) [Member] | Commodity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	5,700,000	4,500,000	1,200,000
Derivative financial instruments, liabilities	(12,600,000)	(53,200,000)	(42,200,000)
Significant Other Observable Inputs (Level 2) [Member] | Foreign currency contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	1,500,000	1,800,000	3,100,000
Derivative financial instruments, liabilities	(500,000)
Significant Other Observable Inputs (Level 2) [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	4,200,000
Derivative financial instruments, liabilities	(60,500,000)	(71,900,000)	(53,200,000)
Unobservable Inputs (Level 3) [Member] | Commodity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets
Derivative financial instruments, liabilities
Unobservable Inputs (Level 3) [Member] | Foreign currency contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets
Derivative financial instruments, liabilities
Unobservable Inputs (Level 3) [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets
Derivative financial instruments, liabilities