Income Taxes - Aggregate Changes in Gross Unrecognized Tax Benefits, Excluding Interest and Penalties (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balances	$ 9,694	$ 8,407	$ 7,724
Increases related to tax positions taken during a prior year	5,845	2,431	333
Decreases related to tax positions taken during a prior year	(686)	(2,212)	(952)
Increases related to tax positions taken during the current year	1,697	1,824	1,880
Decreases related to settlements with taxing authorities	(852)	(756)	(539)
Decreases related to expiration of the statute of limitations	(79)	0	(39)
Ending balances	$ 15,619	$ 9,694	$ 8,407

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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Amount of unrecognized tax benefits.

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

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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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