FAIR VALUE MEASUREMENTS - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Assets:
Available-for-sale debt securities		$ 2,426
Fair Value, Measurements, Recurring \| Galapagos
Liabilities:
Equity investment, current	$ 535	686
Fair Value, Measurements, Recurring \| Arcellx, Inc
Liabilities:
Equity investment, noncurrent	467
Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Total	3,715	8,639
Liabilities:
Total	549	570
Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement \| MYR GmbH
Liabilities:
Liability for MYR GmbH (“MYR”) contingent consideration	222	228
Level 1 \| Fair Value, Measurements, Recurring
Assets:
Total	3,676	6,633
Liabilities:
Total	318	283
Level 1 \| Fair Value, Measurements, Recurring \| MYR GmbH
Liabilities:
Liability for MYR GmbH (“MYR”) contingent consideration	0	0
Level 2 \| Fair Value, Measurements, Recurring
Assets:
Total	39	2,007
Liabilities:
Total	10	59
Level 2 \| Fair Value, Measurements, Recurring \| MYR GmbH
Liabilities:
Liability for MYR GmbH (“MYR”) contingent consideration	0	0
Level 3 \| Fair Value, Measurements, Recurring
Assets:
Total	0	0
Liabilities:
Total	222	228
Level 3 \| Fair Value, Measurements, Recurring \| MYR GmbH
Liabilities:
Liability for MYR GmbH (“MYR”) contingent consideration	222	228
U.S. treasury securities \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Available-for-sale debt securities	0	426
U.S. treasury securities \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	426
U.S. treasury securities \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
U.S. treasury securities \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
U.S. government agencies securities \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Available-for-sale debt securities	0	127
U.S. government agencies securities \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
U.S. government agencies securities \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	127
U.S. government agencies securities \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
Non-U.S. government securities \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Available-for-sale debt securities	0	10
Non-U.S. government securities \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
Non-U.S. government securities \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	10
Non-U.S. government securities \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
Certificates of deposit \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Available-for-sale debt securities	0	45
Certificates of deposit \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
Certificates of deposit \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	45
Certificates of deposit \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
Corporate debt securities \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Available-for-sale debt securities	0	1,451
Corporate debt securities \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
Corporate debt securities \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	1,451
Corporate debt securities \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
Residential mortgage and asset-backed securities \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Available-for-sale debt securities	0	367
Residential mortgage and asset-backed securities \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
Residential mortgage and asset-backed securities \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	367
Residential mortgage and asset-backed securities \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Available-for-sale debt securities	0	0
Money market funds \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Marketable equity securities	1,550	4,465
Money market funds \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Marketable equity securities	1,550	4,465
Money market funds \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Marketable equity securities	0	0
Money market funds \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Marketable equity securities	0	0
Publicly traded equity securities \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Marketable equity securities	1,808	1,458
Publicly traded equity securities \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Marketable equity securities	1,808	1,458
Publicly traded equity securities \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Marketable equity securities	0	0
Publicly traded equity securities \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Marketable equity securities	0	0
Deferred compensation plan \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Marketable equity securities	318	284
Liabilities:
Deferred compensation plan	318	283
Deferred compensation plan \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Marketable equity securities	318	284
Liabilities:
Deferred compensation plan	318	283
Deferred compensation plan \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Marketable equity securities	0	0
Liabilities:
Deferred compensation plan	0	0
Deferred compensation plan \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Marketable equity securities	0	0
Liabilities:
Deferred compensation plan	0	0
Foreign currency derivative contracts \| Fair Value, Measurements, Recurring \| Estimate of Fair Value Measurement
Assets:
Foreign currency derivative contracts	39	7
Liabilities:
Foreign currency derivative contracts	10	59
Foreign currency derivative contracts \| Level 1 \| Fair Value, Measurements, Recurring
Assets:
Foreign currency derivative contracts	0	0
Liabilities:
Foreign currency derivative contracts	0	0
Foreign currency derivative contracts \| Level 2 \| Fair Value, Measurements, Recurring
Assets:
Foreign currency derivative contracts	39	7
Liabilities:
Foreign currency derivative contracts	10	59
Foreign currency derivative contracts \| Level 3 \| Fair Value, Measurements, Recurring
Assets:
Foreign currency derivative contracts	0	0
Liabilities:
Foreign currency derivative contracts	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479581/805-30-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479668/805-30-25-6

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 35
-Paragraph 1
-Subparagraph (b)
-SubTopic 30
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479613/805-30-35-1

+ Details

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

- Definition

Amount excluding accrued interest, 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/2009/role/commonPracticeRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

+ Details

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

- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as noncurrent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482736/825-10-45-1A

+ Details

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

- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483467/210-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482736/825-10-45-1A

+ Details

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

- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482736/825-10-45-1A

+ Details

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

- Definition

Fair value portion of asset contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward contracts, and swaps.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of liability contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into.

+ References

No definition available.

+ Details

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

- Definition

Fair value of financial and nonfinancial obligations.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Fair value portion of other liabilities.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=gild_GalapagosMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=gild_ArcellxIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=gild_MYRGmbHMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- 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_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_CertificatesOfDepositMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_FairValueByAssetClassAxis=gild_ResidentialMortgageAndAssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=gild_DeferredCompensationPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=gild_ForeignCurrencyDerivativeContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: