Financial Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
Total Derivatives, Assets	$ 157.1	$ 227.8
Total Derivatives, Liabilities	106.3	131.9
Designated as Hedging Instrument
Derivative [Line Items]
Total Derivatives, Assets	132.3	222.5
Total Derivatives, Liabilities	79.1	128.7
Designated as Hedging Instrument | Other Receivables | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Assets	25.1	81.7
Designated as Hedging Instrument | Other Receivables | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Assets	16.0	11.1
Designated as Hedging Instrument | Other Noncurrent Assets | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Assets	17.4	27.1
Designated as Hedging Instrument | Other Noncurrent Assets | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Assets	73.8	102.6
Designated as Hedging Instrument | Accrued Liabilities | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	47.4	82.0
Designated as Hedging Instrument | Accrued Liabilities | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	5.5	10.7
Designated as Hedging Instrument | Other Noncurrent Liabilities | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	5.6	13.8
Designated as Hedging Instrument | Other Noncurrent Liabilities | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	20.6	22.2
Not Designated as Hedging Instrument
Derivative [Line Items]
Total Derivatives, Assets	24.8	5.3
Total Derivatives, Liabilities	27.2	3.2
Not Designated as Hedging Instrument | Other Receivables | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Assets	5.6	1.1
Not Designated as Hedging Instrument | Other Receivables | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Assets	0.0	0.0
Not Designated as Hedging Instrument | Other Noncurrent Assets | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Assets	14.2	0.0
Not Designated as Hedging Instrument | Other Noncurrent Assets | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Assets	5.0	4.2
Not Designated as Hedging Instrument | Accrued Liabilities | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	5.3	2.2
Not Designated as Hedging Instrument | Accrued Liabilities | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	0.1	1.0
Not Designated as Hedging Instrument | Other Noncurrent Liabilities | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	21.8	0.0
Not Designated as Hedging Instrument | Other Noncurrent Liabilities | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	$ 0.0	$ 0.0