Cash Payments Made Related to Equity Investments

No definition available.

Name:	gild_CashPaymentsMadeRelatedToEquityInvestments
Namespace Prefix:	gild_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Collaboration Arrangement, License Oral Integrase Inhibitors, Option Period

+ References

No definition available.

+ Details

Name:	gild_CollaborationArrangementLicenseOralIntegraseInhibitorsOptionPeriod
Namespace Prefix:	gild_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Collaboration Arrangement, Net Product Sales Threshold

+ References

No definition available.

+ Details

Name:	gild_CollaborationArrangementNetProductSalesThreshold
Namespace Prefix:	gild_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Collaboration Arrangement, Percent Of Global Development And Commercialization Costs

+ References

No definition available.

+ Details

Name:	gild_CollaborationArrangementPercentOfGlobalDevelopmentAndCommercializationCosts
Namespace Prefix:	gild_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Collaboration Arrangement, Percent Of Global Product Revenues

+ References

No definition available.

+ Details

Name:	gild_CollaborationArrangementPercentOfGlobalProductRevenues
Namespace Prefix:	gild_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity Securities, FV-NI, Maximum Percentage Of Outstanding Stock Allowed To Be Purchased

+ References

No definition available.

+ Details

Name:	gild_EquitySecuritiesFVNIMaximumPercentageOfOutstandingStockAllowedToBePurchased
Namespace Prefix:	gild_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity Securities, FV-NI, Purchase Period

+ References

No definition available.

+ Details

Name:	gild_EquitySecuritiesFVNIPurchasePeriod
Namespace Prefix:	gild_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity Securities, FV-NI, Restriction Period

+ References

No definition available.

+ Details

Name:	gild_EquitySecuritiesFVNIRestrictionPeriod
Namespace Prefix:	gild_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity Securities, FV-NI, Shares

+ References

No definition available.

+ Details

Name:	gild_EquitySecuritiesFVNIShares
Namespace Prefix:	gild_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Equity Securities, FV-NI, Shares Acquired

+ References

No definition available.

+ Details

Name:	gild_EquitySecuritiesFVNISharesAcquired
Namespace Prefix:	gild_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Upfront Collaboration Expenses Related To Other Collaborative Arrangements

+ References

No definition available.

+ Details

Name:	gild_UpfrontCollaborationExpensesRelatedToOtherCollaborativeArrangements
Namespace Prefix:	gild_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130549-203045

+ Details

Name:	us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of cash outflow to acquire investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as investing activity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123583714&loc=SL75117360-209713

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3444-108585

+ Details

Name:	us-gaap_PaymentsToAcquireEquitySecuritiesFvNi
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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

- Details

Name:	us-gaap_TypeOfArrangementAxis=gild_MerckSharpDohmeCorpLicenseAndCollaborationAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=gild_MerckMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=gild_OralFormulationProductMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=gild_InjectableFormulationProductMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=gild_ArcusStockPurchaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=gild_ArcusBiosciencesIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=gild_OtherCollaborationArrangementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_TypeOfArrangementAxis=gild_CommonStockPurchaseAgreementAndInvestorRightsAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

COLLABORATIONS AND OTHER ARRANGEMENTS (Details) - USD ($) shares in Millions				3 Months Ended			9 Months Ended
	Mar. 13, 2021	May 29, 2020	May 27, 2020	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Merck Sharp & Dohme Corp agreement
Collaborative Arrangements
Percent of global development and commercialization costs	60.00%
Revenue recognized				$ 0			$ 0
Option period to license	5 years
Merck Sharp & Dohme Corp agreement \| Merck
Collaborative Arrangements
Percent of global development and commercialization costs	40.00%
Merck Sharp & Dohme Corp agreement \| Oral Formulation Product
Collaborative Arrangements
Net product sales threshold	$ 2,000,000,000
Percent of global product revenues	65.00%
Merck Sharp & Dohme Corp agreement \| Injectable Formulation Product
Collaborative Arrangements
Net product sales threshold	$ 3,500,000,000
Percent of global product revenues	65.00%
Arcus stock purchase agreement \| Arcus
Collaborative Arrangements
Ownership percentage by noncontrolling owners					19.50%
Other collaboration arrangements
Collaborative Arrangements
Cash payments made related to equity investments				0		$ 0	0	$ 0
Upfront collaboration expenses related to other collaborative arrangements				$ 0		$ 0	$ 0	$ 0
Arcus \| Arcus stock purchase agreement
Collaborative Arrangements
Purchase period			5 years
Restriction period			3 years
Equity securities acquired (in shares)		8.2			5.7
Payments to acquire equity securities		$ 261,000,000			$ 220,000,000
Equity securities (in shares)				13.8			13.8
Arcus \| The “Stock Purchase Agreements”
Collaborative Arrangements
Maximum percentage of outstanding stock allowed to be purchased (up to)			35.00%