Contingent payments receivable based on development events.

Name:	nktr_ContingentPaymentsReceivableBasedOnDevelopmentEvents
Namespace Prefix:	nktr
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Development milestone payments receivable upon achievement of milestones.

+ Details

Name:	nktr_DevelopmentMilestonePaymentsReceivableUponAchievementOfMilestones
Namespace Prefix:	nktr
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

License and collaboration agreements.

+ Details

Name:	nktr_LicenseAndCollaborationAgreementsTextualsAbstract
Namespace Prefix:	nktr
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Performance milestone used to reimburse clinical trial costs.

+ Details

Name:	nktr_PerformanceMilestoneUsedToReimburseClinicalTrialCosts
Namespace Prefix:	nktr
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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 SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 13
-Section A

+ Details

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

- Definition

Amount of deferred revenue recognized for transactions arising during the current reporting period. Deferred revenue is a liability as of the balance sheet date 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 SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 13
-Section A

+ Details

Name:	us-gaap_DeferredRevenueAdditions
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

License and Collaboration Agreements (Details Textuals) (USD $) In Millions	3 Months Ended	12 Months Ended							6 Months Ended		3 Months Ended
	Dec. 31, 2009 AstraZeneca AB [Member] Up-front Payment arrangement [Member]	Dec. 31, 2007 Bayer Healthcare LLC [Member] Up-front Payment arrangement [Member]	Dec. 31, 2008 Bayer Healthcare LLC [Member] Performance milestone payments [Member]	Dec. 31, 2007 Bayer Healthcare LLC [Member] Performance milestone payments [Member]	Dec. 31, 2009 F Hoffmann La Roche [Member] License option [Member]	Jun. 30, 2011 AstraZeneca AB [Member]	Jun. 30, 2011 AstraZeneca AB [Member] NKTR-118 [Member]	Jun. 30, 2011 AstraZeneca AB [Member] NKTR-119 [Member]	Jun. 30, 2011 Bayer Healthcare LLC [Member]	Jun. 30, 2011 F Hoffmann La Roche [Member]	Dec. 31, 2010 Amgen Inc [Member]	Jun. 30, 2011 Amgen Inc [Member]
License and Collaboration Agreements (Textuals) [Abstract]
Received upfront payment	$ 125.0	$ 40.0	$ 10.0	$ 10.0	$ 31.0						$ 50.0
Development milestone payments receivable upon achievement of Milestone									60.0
Contingent payments receivable based on development events						310.0	235.0	75.0
Performance milestone used to reimburse clinical trial costs									10.0
Deferred Revenue									$ 29.0	$ 23.1		$ 46.7