Financial Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Total derivatives, asset	$ 307.8	$ 373.7
Total derivatives, liabilities	95.6	95.3
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Total derivatives, asset	285.5	296.6
Total derivatives, liabilities	87.3	65.1
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Total derivatives, asset	22.3	77.1
Total derivatives, liabilities	8.3	30.2
Forward Exchange Contracts [Member] | Designated as Hedging Instrument [Member] | Other Receivables [Member]
Derivative [Line Items]
Total derivatives, asset	86.1	72.3
Forward Exchange Contracts [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member]
Derivative [Line Items]
Total derivatives, asset	39.1	44.4
Forward Exchange Contracts [Member] | Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]
Derivative [Line Items]
Total derivatives, liabilities	60.8	44.0
Forward Exchange Contracts [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [Member]
Derivative [Line Items]
Total derivatives, liabilities	3.9	9.1
Forward Exchange Contracts [Member] | Not Designated as Hedging Instrument [Member] | Other Receivables [Member]
Derivative [Line Items]
Total derivatives, asset	17.9	77.1
Forward Exchange Contracts [Member] | Not Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]
Derivative [Line Items]
Total derivatives, liabilities	7.4	29.5
Interest Rate Management Contract [Member] | Designated as Hedging Instrument [Member] | Other Receivables [Member]
Derivative [Line Items]
Total derivatives, asset	32.3	19.9
Interest Rate Management Contract [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member]
Derivative [Line Items]
Total derivatives, asset	128.0	160.0
Interest Rate Management Contract [Member] | Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]
Derivative [Line Items]
Total derivatives, liabilities	0.1	0.0
Interest Rate Management Contract [Member] | Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [Member]
Derivative [Line Items]
Total derivatives, liabilities	22.5	12.0
Interest Rate Management Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Noncurrent Assets [Member]
Derivative [Line Items]
Total derivatives, asset	4.4	0.0
Interest Rate Management Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Noncurrent Liabilities [Member]
Derivative [Line Items]
Total derivatives, liabilities	$ 0.9	$ 0.7