Debt - Summary of Cash Flows Associated with Commercial Paper (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2017	Sep. 24, 2016	Sep. 26, 2015
Maturities less than 90 days:
Proceeds from/(Repayments of) commercial paper, net	$ (1,782)	$ (869)
Maturities greater than 90 days:
Proceeds from commercial paper	17,932	3,632
Repayments of commercial paper	(12,298)	(3,160)
Proceeds from/(Repayments of) commercial paper, net	5,634	472
Total change in commercial paper, net	$ 3,852	$ (397)	$ 2,191

The net cash inflow or cash outflow from issuing (borrowing) and repaying commercial paper.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 9
-Subparagraph c
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3098-108585

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- Definition

The cash inflow from a borrowing net of the cash outflow from repayment of a borrowing having initial term of repayment of more than three months but less than one year or one operating cycle (if the normal cycle is more than one year).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

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- References

No definition available.

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- Definition

The cash inflow from a borrowing net of the cash outflow from repayment of a borrowing having initial term of repayment within three months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3095-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 9
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3098-108585

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- References

No definition available.

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- Definition

The cash inflow from a borrowing having initial term of repayment of more than three months but less than one year or one operating cycle (if the normal cycle is more than one year).

+ References

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- Definition

The cash outflow from a repayment of a borrowing having initial term of repayment of more than three months but less than one year or one operating cycle (if the normal cycle is more than one year).

+ References

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