Financial Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
Total Derivatives, Assets	$ 146.1	$ 227.8
Total Derivatives, Liabilities	94.1	131.9
Designated as Hedging Instrument
Derivative [Line Items]
Total Derivatives, Assets	117.7	222.5
Total Derivatives, Liabilities	55.5	128.7
Not Designated as Hedging Instrument
Derivative [Line Items]
Total Derivatives, Assets	28.4	5.3
Total Derivatives, Liabilities	38.6	3.2
Forward Exchange Contracts | Designated as Hedging Instrument | Other Receivables
Derivative [Line Items]
Total Derivatives, Assets	24.9	81.7
Forward Exchange Contracts | Designated as Hedging Instrument | Other Noncurrent Assets
Derivative [Line Items]
Total Derivatives, Assets	19.8	27.1
Forward Exchange Contracts | Designated as Hedging Instrument | Accrued Liabilities
Derivative [Line Items]
Total Derivatives, Liabilities	37.0	82.0
Forward Exchange Contracts | Designated as Hedging Instrument | Other Noncurrent Liabilities
Derivative [Line Items]
Total Derivatives, Liabilities	4.6	13.8
Forward Exchange Contracts | Not Designated as Hedging Instrument | Other Receivables
Derivative [Line Items]
Total Derivatives, Assets	7.9	1.1
Forward Exchange Contracts | Not Designated as Hedging Instrument | Other Noncurrent Assets
Derivative [Line Items]
Total Derivatives, Assets	16.2	0.0
Forward Exchange Contracts | Not Designated as Hedging Instrument | Accrued Liabilities
Derivative [Line Items]
Total Derivatives, Liabilities	14.9	2.2
Forward Exchange Contracts | Not Designated as Hedging Instrument | Other Noncurrent Liabilities
Derivative [Line Items]
Total Derivatives, Liabilities	23.7	0.0
Interest Rate Management Contracts | Designated as Hedging Instrument | Other Receivables
Derivative [Line Items]
Total Derivatives, Assets	24.3	11.1
Interest Rate Management Contracts | Designated as Hedging Instrument | Other Noncurrent Assets
Derivative [Line Items]
Total Derivatives, Assets	48.7	102.6
Interest Rate Management Contracts | Designated as Hedging Instrument | Accrued Liabilities
Derivative [Line Items]
Total Derivatives, Liabilities	2.3	10.7
Interest Rate Management Contracts | Designated as Hedging Instrument | Other Noncurrent Liabilities
Derivative [Line Items]
Total Derivatives, Liabilities	11.6	22.2
Interest Rate Management Contracts | Not Designated as Hedging Instrument | Other Receivables
Derivative [Line Items]
Total Derivatives, Assets	4.0	0.0
Interest Rate Management Contracts | Not Designated as Hedging Instrument | Other Noncurrent Assets
Derivative [Line Items]
Total Derivatives, Assets	0.3	4.2
Interest Rate Management Contracts | Not Designated as Hedging Instrument | Accrued Liabilities
Derivative [Line Items]
Total Derivatives, Liabilities	0.0	1.0
Interest Rate Management Contracts | Not Designated as Hedging Instrument | Other Noncurrent Liabilities
Derivative [Line Items]
Total Derivatives, Liabilities	$ 0.0	$ 0.0