Name:	nktr_CollaborativeArrangementsMaximumAggregateAdditionalCashPaymentsReceivableUponAchievementOfDevelopmentAndRegulatoryMilestones
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Eligible additional cash payments receivable upon achievement of certain sales milestones.

No definition available.

Name:	nktr_EligibleAdditionalCashPaymentsReceivableUponAchievementOfCertainSalesMilestones
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Non-refundable upfront payment received in cash in future period.

No definition available.

Name:	nktr_NonRefundableUpfrontPaymentToBeReceivedInCashInFuturePeriod
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Payments received under rights to sublicense agreement.

No definition available.

Name:	nktr_PaymentsReceivedUnderRightsToSublicenseAgreement
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Percentage of development milestones payments, to be received, if conditions occur.

No definition available.

Name:	nktr_PercentageOfDevelopmentMilestonesPaymentsToBeReceivedIfConditionsOccur
Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of development milestones payments, to be received under certain conditions.

No definition available.

Name:	nktr_PercentageOfDevelopmentMilestonesPaymentsToBeReceivedUnderCertainConditions
Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of funding Phase three development costs on an indication by indication basis borne.

No definition available.

Name:	nktr_PercentageOfFundingPhaseThreeDevelopmentCostsOnAnIndicationByIndicationBasisBorne
Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of out of pocket costs to be reimbursed by partner.

No definition available.

Name:	nktr_PercentageOfOutOfPocketCostsToBeReimbursedByPartner
Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of sharing in development costs.

No definition available.

Name:	nktr_PercentageOfSharingInDevelopmentCosts
Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of sharing in Phase 2 development costs.

No definition available.

Name:	nktr_PercentageOfSharingInPhaseTwoDevelopmentCosts
Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of upfront payment, market access milestone payments, royalties and sales milestone payments.

No definition available.

Name:	nktr_PercentageOfUpfrontPaymentMarketAccessMilestonePaymentsRoyaltiesAndSalesMilestonePayments
Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of upfront payment market access milestone payments royalties and sales milestone payments from sublicense agreement retained by our collaboration partner.

No definition available.

Name:	nktr_PercentageOfUpfrontPaymentMarketAccessMilestonePaymentsRoyaltiesAndSalesMilestonePaymentsFromSublicenseAgreementRetainedByOurCollaborationPartner
Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Potential contingent payments based on development events.

No definition available.

Name:	nktr_PotentialContingentPaymentsBasedOnDevelopmentEvents
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Potential development and regulatory milestones.

No definition available.

Name:	nktr_PotentialDevelopmentAndRegulatoryMilestones
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Potential development milestones.

No definition available.

Name:	nktr_PotentialDevelopmentMilestones
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Profits and losses sharing percentage.

No definition available.

Name:	nktr_ProfitsAndLossesSharingPercentage
Namespace Prefix:	nktr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Regulatory milestones payment description.

No definition available.

Name:	nktr_RegulatoryMilestonesPaymentDescription
Namespace Prefix:	nktr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Revenue recognized in period related to performance in prior periods.

No definition available.

Name:	nktr_RevenueRecognizedInPeriodRelatedToPerformanceInPriorPeriods
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Sale of stock consideration expected to be received in future period.

No definition available.

Name:	nktr_SaleOfStockConsiderationExpectedToBeReceivedInFuturePeriod
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Shares of common stock purchased.

No definition available.

Name:	nktr_SharesOfCommonStockPurchased
Namespace Prefix:	nktr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Upfront and milestone payments received from license agreements.

No definition available.

Name:	nktr_UpfrontAndMilestonePaymentsReceivedFromLicenseAgreements
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Upfront and milestone payments received under license agreement.

No definition available.

Name:	nktr_UpfrontAndMilestonePaymentsReceivedUnderLicenseAgreement
Namespace Prefix:	nktr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

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

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.

No definition available.

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

The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3(b).Q1(c))
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6935-107765

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 13.A.4(a).Q1)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3(b).Q2)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3(b))
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3(c).Q3)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

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

The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6935-107765

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3(c).Q3)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.4(a).Q1)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3(b))
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3(b).Q1(c))
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 13.A.3(b).Q2)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

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

Revenue from multiple-deliverable arrangements that include licensing fees and maintenance revenue. Licensing revenue is consideration received from another party for the right to use, but not own, certain of the entity's intangible assets. Licensing arrangements include, but are not limited to, rights to use a patent, copyright, technology, manufacturing process, software or trademark. Licensing fees are generally, but not always, fixed as to amount and not dependent upon the revenue generated by the licensing party. An entity may receive licensing fees for licenses that also generate royalty payments to the entity. Maintenance revenue is derived from maintenance services provided under contracts or arrangements with clients. Services may include the maintenance of software, plant and equipment, and facilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(d),(e))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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

The amount of consideration recognized during the period for the milestone or milestones.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 28
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=68058744&loc=SL6892177-166501

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

Per share or per unit amount of equity securities issued.

No definition available.

Name:	us-gaap_SharesIssuedPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

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

Name:	us-gaap_ConsolidatedEntitiesAxis=us-gaap_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_ProductOrServiceAxis=nktr_NektarTwoOneFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis=nktr_OpdivoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis=nktr_OpdivoAndYervoyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

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

Name:	us-gaap_StatementGeographicalAxis=us-gaap_EuropeanUnionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201409Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_SubsidiarySaleOfStockAxis=nktr_SharePurchaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

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

Name:	us-gaap_DeferredRevenueArrangementTypeAxis=nktr_LicenseArrangementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DeferredRevenueArrangementTypeAxis=nktr_PhaseOneClinicalDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DeferredRevenueArrangementTypeAxis=nktr_DrugProductDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

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

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

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

Name:	us-gaap_DeferredRevenueArrangementTypeAxis=us-gaap_UpFrontPaymentArrangementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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