Derivative Instruments - Schedule of Fair Value of Derivatives (Details) - Level 2 - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Assets and liabilities measured at fair value on a recurring basis
Net derivative asset / (liability) designated as hedging instruments	$ (32.0)	$ (13.0)
Net derivative asset / (liability) not designated as hedging instruments	(5.0)	(4.0)
Forward exchange contracts \| Other current assets
Assets and liabilities measured at fair value on a recurring basis
Forward exchange contracts designated as hedging instruments	4.0	3.0
Forward exchange contracts not designated as hedging instruments, other current assets	3.0	13.0
Forward exchange contracts \| Other assets
Assets and liabilities measured at fair value on a recurring basis
Forward exchange contracts designated as hedging instruments	1.0	1.0
Forward exchange contracts \| Other current liabilities
Assets and liabilities measured at fair value on a recurring basis
Forward exchange contracts designated as hedging instruments	(12.0)	(12.0)
Forward exchange contracts not designated as hedging instruments, other current liabilities	(8.0)	(17.0)
Forward exchange contracts \| Other liabilities
Assets and liabilities measured at fair value on a recurring basis
Forward exchange contracts designated as hedging instruments	(3.0)	(5.0)
Net investment hedges \| Other liabilities
Assets and liabilities measured at fair value on a recurring basis
Forward exchange contract designated as hedging instruments	$ (22.0)	$ 0.0

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://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Fair value as of the balance sheet date of all foreign currency derivative assets not designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
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-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
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-Section 50
-Paragraph 4B
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4B
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
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-Section 45
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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4B
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 4B
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

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-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B

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