Financial Instruments (Schedule of Outstanding Currency Price Risk Management Instruments) (Details) - Forward Exchange Contracts - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
US$ Notional	$ 4,099.5	$ 7,746.8
Years Average Maturity	10 months	8 months
Designated as Hedging Instrument | Cash Flow Hedges
Derivative [Line Items]
US$ Notional	$ 3,150.2	$ 4,130.3
Years Average Maturity	5 months	6 months
Designated as Hedging Instrument | Net Investment Hedges
Derivative [Line Items]
US$ Notional	$ 675.5	$ 968.2
Years Average Maturity	3 years	2 years 8 months
Not Designated as Hedging Instrument
Derivative [Line Items]
US$ Notional	$ 273.8	$ 2,648.3
Years Average Maturity	1 month	5 months