Financial Instruments - Restricted Cash (Details) - USD ($) $ in Millions	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 38,016	$ 48,844
Restricted cash included in other current assets	$ 36	23
Restricted cash and cash equivalents, current, asset, statement of financial position [Extensible List]	us-gaap:OtherAssetsCurrent
Restricted cash included in other non-current assets	$ 1,737	1,357
Restricted cash and cash equivalents, noncurrent, asset, statement of financial position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Cash, cash equivalents and restricted cash	$ 39,789	$ 50,224	$ 25,913	$ 20,289

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Indicates line item in statement of financial position that includes cash and cash equivalents restricted to withdrawal or usage, classified as current.

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Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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