Financial Instruments (Currency Price Risk Management Instruments) (Details) - Forward Exchange Contracts - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019
Derivative [Line Items]
US$ Notional	$ 4,383.1	$ 4,302.5
Years Average Maturity	7 months 6 days	7 months 6 days
Designated as Hedging Instrument | Cash Flow Hedges
Derivative [Line Items]
US$ Notional	$ 2,659.3	$ 2,418.2
Years Average Maturity	6 months	6 months
Designated as Hedging Instrument | Net Investment Hedges
Derivative [Line Items]
US$ Notional	$ 836.2	$ 830.8
Years Average Maturity	8 months 12 days	10 months 24 days
Not Designated as Hedging Instrument
Derivative [Line Items]
US$ Notional	$ 887.6	$ 1,053.5
Years Average Maturity	7 months 6 days	7 months 6 days