Financial Instruments (Schedule of Outstanding Currency Price Risk Management Instruments) (Details) - Forward Exchange Contracts - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018
Derivative [Line Items]
US$ Notional	$ 3,923.7	$ 4,682.7
Years Average Maturity	9 months 18 days	8 months 12 days
Designated as Hedging Instrument | Cash Flow Hedges
Derivative [Line Items]
US$ Notional	$ 2,666.9	$ 2,489.1
Years Average Maturity	6 months	4 months 24 days
Designated as Hedging Instrument | Net Investment Hedges
Derivative [Line Items]
US$ Notional	$ 448.2	$ 457.5
Years Average Maturity	1 year 4 months 24 days	1 year 8 months 12 days
Not Designated as Hedging Instrument
Derivative [Line Items]
US$ Notional	$ 808.6	$ 1,736.1
Years Average Maturity	1 year 3 months 18 days	9 months 18 days