Represents the amount of costs recognized in relation to the separation of the company.

No definition available.

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- Definition

The number of Valvoline Inc. shares owned by Ashland after the initial public offering of Valvoline Inc. was completed.

+ References

No definition available.

+ Details

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- Definition

Amount of net assets (liabilities).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 946
-SubTopic 225
-Section S99
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-Name Accounting Standards Codification
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-Section S99
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- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

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- Definition

Percentage of subsidiary's or equity investee's stock owned by parent company after stock transaction.

+ References

No definition available.

+ Details

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- Definition

Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

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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.

+ Details

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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ash_ValvolineIncMember
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Valvoline - Additional Information (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended		7 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	May 12, 2017	Sep. 30, 2016
Distribution of Valvoline [Line Items]
Valvoline Shares Owned by Ashland					170
Sale of Stock, Percentage of Ownership after Transaction					83.00%
Stockholders' Equity Note, Stock Split, Conversion Ratio					2.745338
Net assets deficit					$ (187)
Discontinued Operations [Member]
Distribution of Valvoline [Line Items]
Separation costs		$ 7		$ 12
Selling, General and Administrative Expense [Member]
Distribution of Valvoline [Line Items]
Separation costs	$ 2	$ 26	$ 8	$ 54
Valvoline Inc. [Member]
Distribution of Valvoline [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners						17.00%