Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Dec. 31, 2014	Sep. 30, 2014
Significant Accounting Policies [Line Items]
Goodwill	$ 524us-gaap_Goodwill	$ 536us-gaap_Goodwill
Value of inventories under FIFO method	46	52
Purification Solutions [Member]
Significant Accounting Policies [Line Items]
Goodwill	$ 452	$ 458
Approximate percentage of fair value of reporting unit exceeds carrying value	9.00%
Successful realization of its anticipated market share, years	3 years
Buildings [Member] \| Minimum [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment	20 years
Buildings [Member] \| Maximum [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment	25 years
Machinery and Equipment [Member] \| Minimum [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment	10 years
Machinery and Equipment [Member] \| Maximum [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment	25 years
Other Fixed Assets [Member] \| Minimum [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment	3 years
Other Fixed Assets [Member] \| Maximum [Member]
Significant Accounting Policies [Line Items]
Useful life of property, plant and equipment	25 years

Realization Of Anticipated Market Share Periods

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- Definition

The excess of replacement or current cost over the stated LIFO (last in first out) inventory value when the LIFO inventory method is utilized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(c))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph c

-Article 5

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- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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- Definition

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.

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

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