Income Taxes - Reconciliation of Beginning and Ending Amount of Gross Unrecognized Tax Benefits, Excluding Related Accrual for Interest (Detail) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2017	Oct. 01, 2016	Oct. 03, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	$ 844	$ 912	$ 803
Increases for current year tax positions	61	71	98
Increases for prior year tax positions	13	142	280
Decreases in prior year tax positions	(55)	(158)	(193)
Settlements with taxing authorities	(31)	(123)	(76)
Balance at the end of the year	$ 832	$ 844	$ 912

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Unrecognized Tax Benefit
-URI http://asc.fasb.org/extlink&oid=6527854

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- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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