Charges on sale of trade receivables.

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- Definition

Valuation allowances are provided against deferred tax assets where management believes that the Company has a 50% or less chance of utilizing the associated benefit in the future.

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No definition available.

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- Definition

Significant accounting policies.

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- Definition

Standard payment term for revenue.

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No definition available.

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- Definition

Amount, after allowance for credit loss, of accounts and financing receivable. Includes, but is not limited to, notes and loan receivable.

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-Publisher FASB
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- Definition

Amount of increase (decrease) in allowance for credit loss on accounts receivable.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

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- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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- Definition

This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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- Definition

Amount before tax of foreign currency transaction realized gain (loss) recognized in the income statement.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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Amount of interest capitalized, including amount of allowance for funds used during construction.

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Amount of dividend income on nonoperating securities.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Significant Accounting Policies - Additional Information (Detail) ¥ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2020 CNY (¥)	Sep. 30, 2019 CNY (¥)
Significant Accounting Policies [Line Items]
Equity affiliate investments		$ 39,000,000	$ 39,000,000
Capitalized interest		2,000,000	4,000,000	$ 2,000,000
Asset retirement obligation reserve		18,000,000	26,000,000
Charges on sale of notes receivables		2,000,000	3,000,000	3,000,000
Changes in allowance		$ 0	0
Chance of utilizing the associated benefit for valuation allowances, maximum		50.00%
Equity Method Investments [Member]
Significant Accounting Policies [Line Items]
Dividends declared		$ 3,000,000	4,000,000	9,000,000
Minimum [Member]
Significant Accounting Policies [Line Items]
Payment terms		0 days
Minimum [Member] \| Buildings [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment		20 years
Minimum [Member] \| Machinery and Equipment [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment		10 years
Minimum [Member] \| Other Fixed Assets [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment		3 years
Minimum [Member] \| Cabot [Member]
Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage		20.00%			20.00%
Maximum [Member]
Significant Accounting Policies [Line Items]
Payment terms		90 days
Maximum [Member] \| Buildings [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment		25 years
Maximum [Member] \| Machinery and Equipment [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment		25 years
Maximum [Member] \| Other Fixed Assets [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment		25 years
Maximum [Member] \| Cabot [Member]
Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage		50.00%			50.00%
Other Nonoperating Income (Expense) [Member]
Significant Accounting Policies [Line Items]
Foreign currency transaction gain (loss)		$ (6,000,000)		$ (4,000,000)
Other Nonoperating Income (Expense) [Member] \| Maximum [Member]
Significant Accounting Policies [Line Items]
Foreign currency transaction gain (loss)			1,000,000
Venezuela [Member] \| Carbon Black Affiliate [Member]
Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage	49.00%
Venezuela [Member] \| Carbon Black Affiliate [Member] \| Other Nonoperating Income (Expense) [Member]
Significant Accounting Policies [Line Items]
Impairment charge	$ 11,000,000
China [Member]
Significant Accounting Policies [Line Items]
Accounts and notes receivable, net		$ 5,000,000	$ 4,000,000		¥ 34	¥ 30