Financial Instruments (Schedule of Outstanding Currency Price Risk Management Instruments) (Details) - Forward Exchange Contracts - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
US$ Notional	$ 4,682.7	$ 4,099.5
Years Average Maturity	8 months 12 days	9 months 18 days
Designated as Hedging Instrument | Cash Flow Hedges
Derivative [Line Items]
US$ Notional	$ 2,489.1	$ 3,150.2
Years Average Maturity	4 months 24 days	4 months 24 days
Designated as Hedging Instrument | Net Investment Hedges
Derivative [Line Items]
US$ Notional	$ 457.5	$ 675.5
Years Average Maturity	1 year 8 months 12 days	3 years
Not Designated as Hedging Instrument
Derivative [Line Items]
US$ Notional	$ 1,736.1	$ 273.8
Years Average Maturity	9 months 18 days	1 month 6 days