Income Taxes - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Tax [Line Items]
Federal statutory tax rate			21.00%	24.50%	35.00%
EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRateNew			21.00%
Tax Cuts and Jobs Act, Income Tax Expense (Benefit)			$ 50	$ (640)
OtherTaxExpenseBenefitRelatedtoHistoricUnremittedForeignEarnings	$ 138	$ 67		138
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	624		624	632	$ 415
Unrecognized tax benefits interest and penalties reflected in current year			26	20	57
Tax reductions related to tax holidays			$ 157	$ 107	$ 146
Income Tax Holiday, Income Tax Benefits Per Share			$ 0.57	$ 0.40	$ 0.65
Income taxes paid, net			$ 536	$ 235	$ 265
Deferred Income Taxes and Other
Income Tax [Line Items]
Indemnification liability, non-current	$ 156		$ 156

The annual statutory tax rate effective upon new U.S. tax legislation.

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Income Tax.

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No definition available.

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Indemnification Liability, Non-current

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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The amount of income taxes from which a reporting entity is exempt or for which it will receive a reduction in income taxes as a result of the income tax holiday granted by the taxing jurisdiction.

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Per share amount effect of the income tax benefit resulting from the income tax holidays granted by taxing jurisdictions.

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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Amount of income tax expense (benefit) from effect of Tax Cuts and Jobs Act.

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Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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