Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 138	$ 160
Short-term debt	132	14
Long-term debt	857	982
Carrying Value \| Foreign exchange forward contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange forward contracts (other assets)	1	1
Foreign exchange forward contracts (other liabilities)	0	2
Carrying Value \| Foreign currency option contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term foreign currency option contracts (other assets)	3	0
Long-term foreign currency option contracts (other asset)	2	2
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	138	160
Short-term debt	249	14
Long-term debt	899	1,051
Fair Value \| Foreign exchange forward contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign exchange forward contracts (other assets)	1	1
Foreign exchange forward contracts (other liabilities)	0	2
Fair Value \| Foreign currency option contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term foreign currency option contracts (other assets)	3	0
Long-term foreign currency option contracts (other asset)	$ 2	$ 2

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents the amount of short-term debt existing as of the balance sheet date.

+ References

No definition available.

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