Derivative Instruments - Pre-tax Amount of Gains (Losses) (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Unrealized Gain (Loss) On Foreign Currency Derivative Net Before Tax, Amount
Pre-tax amount of (losses) gains reclassified from accumulated other comprehensive income into the Consolidated Statement of Operations related to derivative forward exchange contracts designated as cash flow hedges	$ 18.0	$ (24.3)	$ 15.4
Pre-tax amount of gains (losses) from forward exchange contracts not designated as hedging instruments recognized in the Consolidated Statement of Operations	39.1	(8.3)	(5.7)
Forward exchange contracts
Unrealized Gain (Loss) On Foreign Currency Derivative Net Before Tax, Amount
Pre-tax (losses) gains recorded in other comprehensive income related to cash flow hedges	70.5	(10.8)	(9.7)
Pre-tax gains (losses) recorded in other comprehensive income related to net investment hedges	0.0	(0.8)	(1.3)
Treasury locks
Unrealized Gain (Loss) On Foreign Currency Derivative Net Before Tax, Amount
Pre-tax (losses) gains recorded in other comprehensive income related to cash flow hedges	0.0	(28.0)	0.0
Sales
Unrealized Gain (Loss) On Foreign Currency Derivative Net Before Tax, Amount
Pre-tax amount of (losses) gains reclassified from accumulated other comprehensive income into the Consolidated Statement of Operations related to derivative forward exchange contracts designated as cash flow hedges	0.7	1.9	(0.7)
Cost of sales
Unrealized Gain (Loss) On Foreign Currency Derivative Net Before Tax, Amount
Pre-tax amount of (losses) gains reclassified from accumulated other comprehensive income into the Consolidated Statement of Operations related to derivative forward exchange contracts designated as cash flow hedges	21.8	(25.4)	19.6
Pre-tax amount of gains (losses) from forward exchange contracts not designated as hedging instruments recognized in the Consolidated Statement of Operations	0.5	(0.2)	6.1
Selling, general and administrative expenses
Unrealized Gain (Loss) On Foreign Currency Derivative Net Before Tax, Amount
Pre-tax amount of (losses) gains reclassified from accumulated other comprehensive income into the Consolidated Statement of Operations related to derivative forward exchange contracts designated as cash flow hedges	(0.9)	1.5	(1.4)
Interest income
Unrealized Gain (Loss) On Foreign Currency Derivative Net Before Tax, Amount
Pre-tax amount of (losses) gains reclassified from accumulated other comprehensive income into the Consolidated Statement of Operations related to derivative forward exchange contracts designated as cash flow hedges	(3.6)	(2.3)	(2.1)
Pre-tax amount of net gains recognized within the Consolidated Statement of Operations related to derivative instruments designated as fair value hedges, which fully offset the related net gains on the hedged debt instruments	0.0	0.0	15.1
Other (expense) income
Unrealized Gain (Loss) On Foreign Currency Derivative Net Before Tax, Amount
Pre-tax amount of gains (losses) from forward exchange contracts not designated as hedging instruments recognized in the Consolidated Statement of Operations	$ 38.6	$ (8.1)	$ (11.8)

The amount of net gains or losses on foreign currency cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings.

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