Leases - Schedule of Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
Jun. 30, 2026	Jun. 30, 2025
Right-of-use assets obtained in exchange for lease obligations:
Operating leases (non-cash activity)	$ 64	$ 65
Operating cash flows:
Cash paid for amounts included in the measurement of lease liabilities	$ 84	$ 81

Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-3

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
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-Name Accounting Standards Codification
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-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
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-Section 50
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-Publisher FASB
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Name:	us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration