Financial Instruments (Fair Value and Balance Sheet Location of Derivatives) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019
Derivative [Line Items]
Total Derivatives, Assets	$ 274.2	$ 224.2
Total Derivatives, Liabilities	84.3	112.4
Designated as Hedging Instrument
Derivative [Line Items]
Total Derivatives, Assets	224.0	176.6
Total Derivatives, Liabilities	43.0	56.3
Designated as Hedging Instrument | Other Receivables and Current Assets | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Assets	90.7	79.0
Designated as Hedging Instrument | Other Receivables and Current Assets | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Assets	33.7	24.8
Designated as Hedging Instrument | Other Noncurrent Assets | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Assets	16.3	11.9
Designated as Hedging Instrument | Other Noncurrent Assets | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Assets	83.3	60.9
Designated as Hedging Instrument | Accrued Liabilities | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	40.5	53.8
Designated as Hedging Instrument | Accrued Liabilities | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	0.5	1.1
Designated as Hedging Instrument | Other Noncurrent Liabilities | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	2.0	0.7
Designated as Hedging Instrument | Other Noncurrent Liabilities | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	0.0	0.7
Not Designated as Hedging Instrument
Derivative [Line Items]
Total Derivatives, Assets	50.2	47.6
Total Derivatives, Liabilities	41.3	56.1
Not Designated as Hedging Instrument | Other Receivables and Current Assets | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Assets	40.0	38.7
Not Designated as Hedging Instrument | Other Noncurrent Assets | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Assets	10.2	8.4
Not Designated as Hedging Instrument | Other Noncurrent Assets | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Assets	0.0	0.5
Not Designated as Hedging Instrument | Accrued Liabilities | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	19.7	36.3
Not Designated as Hedging Instrument | Other Noncurrent Liabilities | Forward Exchange Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	21.6	19.8
Not Designated as Hedging Instrument | Other Noncurrent Liabilities | Interest Rate Management Contracts
Derivative [Line Items]
Total Derivatives, Liabilities	$ 0.0	$ 0.0