Fair Value Measurements - Schedule of Assets and Liabilities at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2021	Sep. 30, 2020
Foreign Exchange Contract [Member] \| Not Designated as Hedging Instrument
Liabilities, Fair Value Disclosure [Abstract]
Derivative, Notional Amount	$ 156	$ 149
Fair Value, Inputs, Level 1 [Member]
Other noncurrent assets
Assets, Fair Value Disclosure	17	296
Fair Value, Inputs, Level 2 [Member]
Other noncurrent assets
Assets, Fair Value Disclosure	72	150
Liabilities, Fair Value Disclosure [Abstract]
Financial and Nonfinancial Liabilities, Fair Value Disclosure	2	3
Fair Value Measured at Net Asset Value Per Share
Other noncurrent assets
Non-qualified trust funds	8	8
Liabilities, Fair Value Disclosure [Abstract]
Deferred compensation obligations	25	25
Fair Value, Measurements, Recurring
Prepaid Expense and Other Assets, Current [Abstract]
Currency derivatives	2	3
Other noncurrent assets
Non-qualified trust funds	12	16
Interest Rate Derivative Assets, at Fair Value	2
Assets, Fair Value Disclosure	97	454
Liabilities, Fair Value Disclosure [Abstract]
Currency derivatives	1	2
Interest rate swap agreements	1	1
Deferred compensation obligations	25	25
Financial and Nonfinancial Liabilities, Fair Value Disclosure	27	28
Fair Value, Measurements, Recurring \| Money Market Funds [Member]
Cash and cash equivalents
Cash and Cash Equivalents, Fair Value Disclosure	17	296
Fair Value, Measurements, Recurring \| Time deposits
Cash and cash equivalents
Cash and Cash Equivalents, Fair Value Disclosure	64	139
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1 [Member] \| Money Market Funds [Member]
Cash and cash equivalents
Cash and Cash Equivalents, Fair Value Disclosure	17	296
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 [Member]
Prepaid Expense and Other Assets, Current [Abstract]
Currency derivatives	2	3
Other noncurrent assets
Non-qualified trust funds	4	8
Interest Rate Derivative Assets, at Fair Value	2
Liabilities, Fair Value Disclosure [Abstract]
Currency derivatives	1	2
Interest rate swap agreements	1	1
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 [Member] \| Time deposits
Cash and cash equivalents
Cash and Cash Equivalents, Fair Value Disclosure	64	139
Fair Value, Measurements, Recurring \| Fair Value Measured at Net Asset Value Per Share
Other noncurrent assets
Non-qualified trust funds	8	8
Liabilities, Fair Value Disclosure [Abstract]
Deferred compensation obligations	$ 25	$ 25

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
-Topic 815
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-Section 50
-Paragraph 1A
-Subparagraph (d)
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Fair value portion of asset contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward contracts, and swaps.

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Fair value portion of liability contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into.

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- Definition

Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959

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Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Fair value of financial and nonfinancial obligations.

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Amount of the liabilities, classified as other, for deferred compensation arrangements payable after one year or the operating cycle, if longer.

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