Consideration received for product delivered.

No definition available.

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

- Definition

Contingent payments receivable based on development events.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Increase Decrease In Revenue

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Liability to AZ for DTC advertising payments.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Payment made to Bayer for cost of Phase 3 clinical trial.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of post approval study costs to repay.

+ References

No definition available.

+ Details

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- Definition

Potential development milestones.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Potential Reduction In Future Royalty Payments To Repay Post Approval Studies

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

Potential royalty reduction on sales to repay post-approval study if required.

+ References

No definition available.

+ Details

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

- Definition

Upfront and Milestone Payments Received Under License Agreement

+ References

No definition available.

+ Details

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

- Definition

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.

+ References

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.4(a).Q1 Response)

-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 13

-Section A

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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

- Definition

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

+ References

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=51671726&loc=SL6892177-166501

+ Details

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

- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Data Type:	na
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Period Type:

- Details

Name:	us-gaap_PrincipleTransactionRevenueDescriptionOfReportingCategoryAxis=nktr_PerformanceMilestonePaymentsMember
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Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Data Type:	na
Balance Type:
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- Details

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Data Type:	na
Balance Type:
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherCurrentLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

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Data Type:	na
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- Details

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- Details

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Data Type:	na
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- Details

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- Details

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- Details

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License and Collaboration Agreements - Additional Information (Detail) - USD ($)		1 Months Ended						3 Months Ended				6 Months Ended	12 Months Ended
	Sep. 16, 2014	Oct. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Nov. 30, 2013	Jun. 30, 2013	Feb. 29, 2012	Mar. 31, 2015	Dec. 31, 2013	Dec. 31, 2010	Dec. 31, 2009	Jun. 30, 2015	Dec. 31, 2007	Jul. 31, 2016	Jul. 31, 2015
Deferred Revenue Arrangement [Line Items]
Potential future additional payments for development milestones												$ 128,300,000
Roche [Member] \| MIRCERA [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenue												8,100,000
Consideration received for product delivered in 2013									$ 18,600,000
Roche [Member] \| MIRCERA [Member] \| Performance-based Milestone Payments [Member]
Deferred Revenue Arrangement [Line Items]
Received upfront and milestone payments							$ 22,000,000
Roche [Member] \| MIRCERA [Member] \| Upfront Payment Arrangement in 2007 [Member]
Deferred Revenue Arrangement [Line Items]
Received upfront and milestone payments							$ 5,000,000
Roche [Member] \| PEGASYS [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenue												2,600,000
Roche [Member] \| PEGASYS and MIRCERA [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenue												3,400,000
Amgen, Inc. [Member]
Deferred Revenue Arrangement [Line Items]
Received upfront and milestone payments										$ 50,000,000
Deferred revenue												26,700,000
Ophthotech Corporation [Member] \| Fovista [Member]
Deferred Revenue Arrangement [Line Items]
Potential future additional payments for development milestones												9,500,000
Received upfront and milestone payments				$ 19,750,000
Deferred revenue												18,200,000
AstraZeneca AB [Member] \| United States [Member]
Deferred Revenue Arrangement [Line Items]
Liability to AZ for DTC advertising payments								$ 10,000,000
Reduction of revenue								(10,000,000)
AstraZeneca AB [Member] \| United States [Member] \| Other Current Liabilities [Member]
Deferred Revenue Arrangement [Line Items]
Liability to AZ for DTC advertising payments												5,000,000
AstraZeneca AB [Member] \| United States [Member] \| Other Long-Term Liabilities [Member]
Deferred Revenue Arrangement [Line Items]
Liability to AZ for DTC advertising payments												5,000,000
AstraZeneca AB [Member] \| Scenario, Forecast [Member] \| United States [Member]
Deferred Revenue Arrangement [Line Items]
Liability to AZ for DTC advertising payments														$ 5,000,000	$ 5,000,000
AstraZeneca AB [Member] \| MOVANTIK [Member]
Deferred Revenue Arrangement [Line Items]
Received upfront and milestone payments		$ 35,000,000			$ 70,000,000			$ 100,000,000
Deferred revenue												0
Percentage of post approval study costs to repay	33.00%
Maximum potential reduction in royalties	$ 35,000,000
AstraZeneca AB [Member] \| MOVANTIK [Member] \| European Union [Member]
Deferred Revenue Arrangement [Line Items]
Contingent payments receivable based on development events regulatory to be pursued and completed solely by others												40,000,000
AstraZeneca AB [Member] \| MOVANTIK [Member] \| United States [Member]
Deferred Revenue Arrangement [Line Items]
Potential reduction in U.S. royalty rate for repayment	2.00%
AstraZeneca AB [Member] \| MOVANTIKTM (NKTR-118) and MOVANTIKTM fixed-dose combination program (NKTR-119) [Member] \| Upfront Payment Arrangement in 2007 [Member]
Deferred Revenue Arrangement [Line Items]
Received upfront and milestone payments											$ 125,000,000
AstraZeneca AB [Member] \| Movantik Fixed-dose Combination Program [Member]
Deferred Revenue Arrangement [Line Items]
Contingent payments receivable based on development events regulatory to be pursued and completed solely by others												75,000,000
Bayer Healthcare LLC [Member]
Deferred Revenue Arrangement [Line Items]
Potential future additional payments for development milestones												50,000,000
Deferred revenue												20,000,000
Payment made to Bayer for cost of Phase 3 clinical trial						$ 10,000,000
Bayer Healthcare LLC [Member] \| Performance-based Milestone Payments [Member]
Deferred Revenue Arrangement [Line Items]
Received upfront and milestone payments												30,000,000
Bayer Healthcare LLC [Member] \| Upfront Payment Arrangement in 2007 [Member]
Deferred Revenue Arrangement [Line Items]
Received upfront and milestone payments													$ 40,000,000
Baxalta [Member] \| BAX 855 (Hemophilia) [Member]
Deferred Revenue Arrangement [Line Items]
Potential future additional payments for development milestones												20,000,000
Deferred revenue												0
Development milestones achieved			$ 8,000,000
Baxalta [Member] \| BAX 855 (Hemophilia) [Member] \| United States [Member]
Deferred Revenue Arrangement [Line Items]
Potential future additional payments for development milestones												10,000,000
Other [Member]
Deferred Revenue Arrangement [Line Items]
Potential future additional payments for development milestones												51,800,000
Deferred revenue												$ 18,000,000