Derivative Instruments - Schedule of Fair Value of Derivatives (Details) - Level 2 - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Assets and liabilities measured at fair value on a recurring basis
Net derivative asset / (liability) designated as hedging instruments	$ 26.4	$ 49.0
Net derivative asset / (liability) not designated as hedging instruments	11.3	38.9
Forward exchange contracts \| Other current assets
Assets and liabilities measured at fair value on a recurring basis
Forward exchange contracts designated as hedging instruments	23.5	52.2
Forward exchange contracts not designated as hedging instruments, other current assets	20.1	59.9
Forward exchange contracts \| Other assets
Assets and liabilities measured at fair value on a recurring basis
Forward exchange contracts designated as hedging instruments	5.6	8.0
Forward exchange contracts \| Other current liabilities
Assets and liabilities measured at fair value on a recurring basis
Forward exchange contracts designated as hedging instruments	(2.0)	(10.2)
Forward exchange contracts not designated as hedging instruments, other current liabilities	(8.8)	(21.0)
Forward exchange contracts \| Other liabilities
Assets and liabilities measured at fair value on a recurring basis
Forward exchange contracts designated as hedging instruments	$ (0.7)	$ (1.0)

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-SubTopic 10
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480463/815-10-45-5

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Fair value as of the balance sheet date of all foreign currency derivative assets designated as cash flow hedging instruments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B

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-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B

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