Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk - Realized Gains/Losses on Derivative Contracts (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	$ 18.9	$ 73.9	$ 60.3	$ 94.3
Foreign Exchange Forward [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	4.0	2.1	9.7	7.7
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	0	0.1	0.1	0.7
Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	$ 22.9	$ 76.1	$ 70.1	$ 102.7