Debt - Summary of Cash Flows Associated with Commercial Paper (Details) - USD ($) $ in Millions	6 Months Ended
Mar. 31, 2018	Apr. 01, 2017
Maturities 90 days or less:
Proceeds from/(Repayments of) commercial paper, net	$ 4,070	$ (1,318)
Maturities greater than 90 days:
Proceeds from commercial paper	5,550	7,057
Repayments of commercial paper	(9,619)	(3,860)
Proceeds from/(Repayments of) commercial paper, net	(4,069)	3,197
Total change in commercial paper, net	$ 1	$ 1,879

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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Period Type:	duration

- 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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