Financial Instruments - Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Millions	Sep. 28, 2019	Sep. 29, 2018
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	$ 204,977	$ 241,180
Unrealized Gains	1,202	209
Unrealized Losses	(281)	(4,289)
Fair Value	205,898	237,100
Cash and Cash Equivalents	48,844	25,913
Short-Term Marketable Securities	51,713	40,388
Long-Term Marketable Securities	105,341	170,799
Total cash, cash equivalents and marketable securities that were restricted from general use	18,900	20,300
Level 1
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	15,897	8,882
Unrealized Gains	0	0
Unrealized Losses	0	(116)
Fair Value	15,897	8,766
Cash and Cash Equivalents	15,897	8,083
Short-Term Marketable Securities	0	683
Long-Term Marketable Securities	0	0
Level 2
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	176,876	220,723
Unrealized Gains	1,202	209
Unrealized Losses	(281)	(4,173)
Fair Value	177,797	216,759
Cash and Cash Equivalents	20,743	6,255
Short-Term Marketable Securities	51,713	39,705
Long-Term Marketable Securities	105,341	170,799
Cash
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	12,204	11,575
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	12,204	11,575
Cash and Cash Equivalents	12,204	11,575
Short-Term Marketable Securities	0	0
Long-Term Marketable Securities	0	0
Money market funds \| Level 1
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	15,897	8,083
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	15,897	8,083
Cash and Cash Equivalents	15,897	8,083
Short-Term Marketable Securities	0	0
Long-Term Marketable Securities	0	0
Mutual funds \| Level 1
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost		799
Unrealized Gains		0
Unrealized Losses		(116)
Fair Value		683
Cash and Cash Equivalents		0
Short-Term Marketable Securities		683
Long-Term Marketable Securities		0
U.S. Treasury securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	30,293	47,296
Unrealized Gains	33	0
Unrealized Losses	(62)	(1,202)
Fair Value	30,264	46,094
Cash and Cash Equivalents	6,165	1,613
Short-Term Marketable Securities	9,817	7,606
Long-Term Marketable Securities	14,282	36,875
U.S. agency securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	9,767	4,127
Unrealized Gains	1	0
Unrealized Losses	(3)	(48)
Fair Value	9,765	4,079
Cash and Cash Equivalents	6,489	1,732
Short-Term Marketable Securities	2,249	360
Long-Term Marketable Securities	1,027	1,987
Non-U.S. government securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	19,821	21,601
Unrealized Gains	337	49
Unrealized Losses	(50)	(250)
Fair Value	20,108	21,400
Cash and Cash Equivalents	749	0
Short-Term Marketable Securities	3,168	3,355
Long-Term Marketable Securities	16,191	18,045
Certificates of deposit and time deposits \| Level 2
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	4,041	3,074
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	4,041	3,074
Cash and Cash Equivalents	2,024	1,247
Short-Term Marketable Securities	1,922	1,330
Long-Term Marketable Securities	95	497
Commercial paper \| Level 2
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	12,433	2,573
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	12,433	2,573
Cash and Cash Equivalents	5,193	1,663
Short-Term Marketable Securities	7,240	910
Long-Term Marketable Securities	0	0
Corporate debt securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	85,383	123,001
Unrealized Gains	756	152
Unrealized Losses	(92)	(2,038)
Fair Value	86,047	121,115
Cash and Cash Equivalents	123	0
Short-Term Marketable Securities	26,127	25,162
Long-Term Marketable Securities	59,797	95,953
Municipal securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	958	946
Unrealized Gains	8	0
Unrealized Losses	(1)	(12)
Fair Value	965	934
Cash and Cash Equivalents	0	0
Short-Term Marketable Securities	68	178
Long-Term Marketable Securities	897	756
Mortgage- and asset-backed securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
Adjusted Cost	14,180	18,105
Unrealized Gains	67	8
Unrealized Losses	(73)	(623)
Fair Value	14,174	17,490
Cash and Cash Equivalents	0	0
Short-Term Marketable Securities	1,122	804
Long-Term Marketable Securities	$ 13,052	$ 16,686

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3044-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CashAndCashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in marketable security, classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_MarketableSecuritiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in marketable security, classified as noncurrent.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_MarketableSecuritiesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

+ References

No definition available.

+ Details

Name:	us-gaap_RestrictedInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CashMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MutualFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_BankTimeDepositsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: