Charges on sale of trade receivables.

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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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Reclassification of deferred tax assets net current to deferred tax assets net non current.

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Reclassification of deferred tax liabilities current to deferred tax liabilities non current.

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Significant accounting policies.

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Carrying amount as of the balance sheet date, net of allowance for doubtful accounts, of account and note receivables due from other than related parties.

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Amount of increase (decrease) in the allowance for doubtful accounts.

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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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This item represents disclosure of the amount of dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporation; these investments are accounted for under the equity method of accounting. This element excludes distributions that constitute a return of investment, which are classified as investing activities.

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

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Amount of interest capitalized, including amount of allowance for funds used during construction.

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Gross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.

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Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale.

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Amount of noncurrent assets classified as other.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer.

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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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Percentage of fair value of reporting unit in excess of carrying amount.

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Significant Accounting Policies - Additional Information (Detail) ¥ in Millions	12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2017 CNY (¥)	May 31, 2017	Sep. 30, 2016 CNY (¥)
Significant Accounting Policies [Line Items]
Prepaid expenses and other current assets	$ 59,000,000	$ 49,000,000
Other assets	46,000,000	40,000,000
Equity affiliate investments	56,000,000	53,000,000
Dividends declared	11,000,000	9,000,000	$ 14,000,000
Investments in marketable securities	3,000,000	2,000,000
Capitalized interest	1,000,000	1,000,000
Inventory, assets held for rent	5,000,000	10,000,000
Asset retirement obligation reserve	26,000,000	22,000,000
Charges on sale of notes receivables	2,000,000	1,000,000	3,000,000
Changes in allowance	$ 0	0
Chance of utilizing the associated benefit for valuation allowances, maximum	50.00%
China [Member]
Significant Accounting Policies [Line Items]
Accounts and notes receivable, net	$ 11,000,000	15,000,000		¥ 73		¥ 102
Other Nonoperating Income (Expense) [Member]
Significant Accounting Policies [Line Items]
Foreign currency transaction gains (losses)	$ (4,000,000)	(7,000,000)	(8,000,000)
Purification Solutions [Member]
Significant Accounting Policies [Line Items]
Percentage of fair value in excess of carrying amount					13.00%
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]
Capitalized interest			1,000,000
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%
Accounting Standards Update 2015-03 [Member] \| Restatement Adjustment [Member]
Significant Accounting Policies [Line Items]
Prepaid expenses and other current assets		1,000,000	1,000,000
Other assets		3,000,000	2,000,000
Adjustments for New Accounting Principle Early Adoption [Member]
Significant Accounting Policies [Line Items]
Reclassification of current deferred tax assets to noncurrent deferred tax assets		41,000,000	43,000,000
Reclassification of current deferred tax liabilities to noncurrent deferred tax liabilities		$ 1,000,000	$ 1,000,000