Fair Value Measurement (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Sep. 30, 2011	Jun. 30, 2011
Commodity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	$ 17.4	$ 6.8	$ 10.7
Derivative financial instruments, liabilities	(120.0)	(44.2)	(23.8)
Foreign currency contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets	7.1	5.3
Derivative financial instruments, liabilities		(3.3)	(6.1)
Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial instruments, assets			5.0
Derivative financial instruments, liabilities	(67.0)	(44.4)	(3.6)
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	5.1	3.5	0.6
Derivative financial instruments, liabilities	(18.0)	(28.1)	(12.2)
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
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	12.3	3.3	10.1
Derivative financial instruments, liabilities	(102.0)	(16.1)	(11.6)
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	7.1	5.3
Derivative financial instruments, liabilities		(3.3)	(6.1)
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			5.0
Derivative financial instruments, liabilities	(67.0)	(44.4)	(3.6)
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