Financial Instruments (Gains and Losses Recognized In Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Net Investment Hedging Relationships
Tax effects		$ (11.3)	$ (8.0)	$ (0.5)	$ (12.9)
Net Amount Recognized in OCI		(398.2)	51.3	(134.2)	(16.8)
Derivatives in Cash Flow Hedging Relationships
Tax effects		(6.0)		(8.6)
Net Amount Recognized in OCI		(27.4)		(5.3)
Tax effects			8.7		9.4
Net Amount Recognized in OCI			(35.4)		(45.7)
Net Investment Hedges
Net Investment Hedging Relationships
Total Amount Recognized in OCI		69.6		27.1
Total Amount Recognized in OCI			27.4		56.4
Tax effects		(16.8)	(6.7)	(6.6)	(13.7)
Net Amount Recognized in OCI		52.8	20.7	20.5	42.7
Net Investment Hedges | Forward Exchange Contracts
Net Investment Hedging Relationships
Total Amount Recognized in OCI		40.5		31.4
Total Amount Recognized in OCI			8.2		23.7
Net Investment Hedges | Foreign Currency Debt
Net Investment Hedging Relationships
Total Amount Recognized in OCI		16.7		(13.2)
Total Amount Recognized in OCI			22.7		35.3
Net Investment Hedges | Cross Currency Interest Rate Swaps
Net Investment Hedging Relationships
Total Amount Recognized in OCI		12.4		8.9
Total Amount Recognized in OCI			(3.5)		(2.6)
Cash Flow Hedges
Derivatives in Cash Flow Hedging Relationships
Total Amount Recognized in OCI		(21.4)		3.3
Tax effects		(6.0)		(8.6)
Net Amount Recognized in OCI		(27.4)		(5.3)
Total Amount Recognized in OCI			(44.1)		(55.1)
Tax effects			8.7		9.4
Net Amount Recognized in OCI			(35.4)		(45.7)
Cash Flow Hedges | Forward Exchange Contracts
Derivatives in Cash Flow Hedging Relationships
Total Amount Recognized in OCI		(10.1)		16.2
Total Amount Recognized in OCI			(22.2)		(13.3)
Cash Flow Hedges | Forward Exchange Contracts, Excluded Components
Derivatives in Cash Flow Hedging Relationships
Total Amount Recognized in OCI		(2.8)		(7.3)
Total Amount Recognized in OCI			(3.6)		(7.4)
Cash Flow Hedges | Other
Derivatives in Cash Flow Hedging Relationships
Total Amount Recognized in OCI	[1]	$ (8.5)		$ (5.6)
Total Amount Recognized in OCI	[1]		$ (18.3)		$ (34.4)

[1] Other primarily includes interest rate and cross currency interest rate swaps for which excluded components are recognized in “Payables and accrued liabilities” and “Other receivables and current assets” as a component of accrued interest payable and accrued interest receivable, respectively. These excluded components are recorded in “Other Non-operating income (expense), net” over the life of the cross currency interest rate swap.