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Income Tax - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Mar. 31, 2016 | Mar. 31, 2015 | Mar. 31, 2016 | Mar. 31, 2015
Income Taxes [Line Items] |  |  |  |
Provision for income taxes | $ 11 | $ 14 | $ 6 | $ 17
Effective tax rate | 20.00% | 36.00% | 12.00% | 18.00%
Net discrete tax (benefits) charges related to tax settlements | $ 1 | $ 4 | $ (5) | $ 9
Uncertain tax positions from expirations of statute of limitations | $ 1 | $ 1 | $ 3 | $ 12
Earliest Tax Year [Member] | Internal Revenue Service (IRS) [Member] |  |  |  |
Income Taxes [Line Items] |  |  |  |
Tax years remain subject to examination | 2012 |  |  |
Earliest Tax Year [Member] | State Tax Authorities [Member] |  |  |  |
Income Taxes [Line Items] |  |  |  |
Tax years remain subject to examination | 2005 |  |  |
Earliest Tax Year [Member] | Non-U.S. Jurisdictions [Member] |  |  |  |
Income Taxes [Line Items] |  |  |  |
Tax years remain subject to examination | 2004 |  |  |
Latest Tax Year [Member] | Internal Revenue Service (IRS) [Member] |  |  |  |
Income Taxes [Line Items] |  |  |  |
Tax years remain subject to examination | 2015 |  |  |
Latest Tax Year [Member] | State Tax Authorities [Member] |  |  |  |
Income Taxes [Line Items] |  |  |  |
Tax years remain subject to examination | 2015 |  |  |
Latest Tax Year [Member] | Non-U.S. Jurisdictions [Member] |  |  |  |
Income Taxes [Line Items] |  |  |  |
Tax years remain subject to examination | 2015 |  |  |

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- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Income Tax Expense (or Benefit) -URI http://asc.fasb.org/extlink&oid=6515339 + Details
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