Document and Entity Information (USD $)	9 Months Ended
Document and Entity Information (USD $)	Sep. 30, 2011	Oct. 31, 2011	Jun. 30, 2010
Document and Entity Information [Abstract]
Entity Registrant Name	NEKTAR THERAPEUTICS
Entity Central Index Key	0000906709
Document Type	10-Q
Document Period End Date	Sep. 30, 2011
Amendment Flag	false
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,134,446,342
Entity Common Stock, Shares Outstanding		114,426,466

Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 43,008	$ 17,755
Short-term investments	223,479	298,177
Accounts receivable	12,914	25,102
Inventory	10,654	7,266
Other current assets	7,565	5,679
Total current assets	297,620	353,979
Long-term investments	191,478	0
Property and equipment, net	81,649	89,773
Goodwill	76,501	76,501
Other assets	845	972
Total assets	648,093	521,225
Current liabilities:
Accounts payable	2,175	7,194
Accrued compensation	11,760	9,252
Accrued expenses	11,777	8,540
Accrued clinical trial expenses	13,612	12,144
Deferred revenue, current portion	19,982	20,584
Convertible subordinated notes, current portion	214,955	0
Other current liabilities	4,781	6,394
Total current liabilities	279,042	64,108
Convertible subordinated notes	0	214,955
Capital lease obligations, less current portion	15,250	17,014
Deferred revenue, less current portion	113,045	124,763
Deferred gain	3,497	4,152
Other long-term liabilities	6,462	5,571
Total liabilities	417,296	430,563
Commitments and contingencies
Stockholders' equity:
Preferred stock, 10,000 shares authorized Series A, $0.0001 par value; 3,100 shares designated; no shares issued or outstanding at September 30, 2011 and December 31, 2010
Common stock, $0.0001 par value; 300,000 authorized; 114,426 shares and 94,517 shares issued and outstanding at September 30, 2011 and December 31, 2010, respectively	11	9
Capital in excess of par value	1,592,803	1,354,232
Accumulated other comprehensive (loss) income	(987)	968
Accumulated deficit	(1,361,030)	(1,264,547)
Total stockholders' equity	230,797	90,662
Total liabilities and stockholders' equity	$ 648,093	$ 521,225

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Stockholders' equity:
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized Series A	10,000	10,000
Preferred stock, shares designated	3,100	3,100
Preferred stock, shares issued
Preferred stock, shares outstanding
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000	300,000
Common stock, shares issued	114,426	94,517
Common stock, shares outstanding	114,426	94,517

Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Revenue:
Product sales and royalties	$ 10,222	$ 7,230	$ 26,023	$ 21,968
License, collaboration and other	16,846	30,695	29,675	91,757
Total revenue	27,068	37,925	55,698	113,725
Operating costs and expenses:
Cost of goods sold	5,038	6,245	16,441	15,430
Research and development	31,018	27,724	93,464	76,610
General and administrative	12,350	10,181	35,262	29,401
Total operating costs and expenses	48,406	44,150	145,167	121,441
Loss from operations	(21,338)	(6,225)	(89,469)	(7,716)
Non-operating income (expense):
Interest income	622	369	1,583	1,225
Interest expense	(2,543)	(2,826)	(7,698)	(8,686)
Other income (expense), net	(717)	249	(599)	436
Total non-operating expense	(2,638)	(2,208)	(6,714)	(7,025)
Loss before provision for income taxes	(23,976)	(8,433)	(96,183)	(14,741)
Provision for income taxes	92	278	300	617
Net loss	$ (24,068)	$ (8,711)	$ (96,483)	$ (15,358)
Basic and diluted net loss per share	$ (0.21)	$ (0.09)	$ (0.86)	$ (0.16)
Weighted average shares outstanding used in computing basic and diluted net loss per share	114,413	94,213	112,435	93,972

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities:
Net loss	$ (96,483)	$ (15,358)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	11,424	12,499
Stock-based compensation	14,501	12,716
Other non-cash transactions	967	(176)
Changes in operating assets and liabilities:
Accounts receivable	12,188	(752)
Inventory	(3,388)	(4,989)
Other assets	(1,750)	1
Accounts payable	(4,200)	1,755
Accrued compensation	2,508	500
Accrued expenses	6,238	4,090
Accrued clinical trial expenses	1,468	(1,408)
Deferred revenue	(12,320)	(83,107)
Other liabilities	(2,681)	(2,049)
Net cash used in operating activities	(71,528)	(76,278)
Cash flows from investing activities:
Purchases of investments	(627,529)	(315,160)
Sales of investments	218,660	10,290
Maturities of investments	290,810	360,906
Purchases of property and equipment	(8,294)	(22,160)
Net cash (used in) provided by investing activities	(126,353)	33,876
Cash flows from financing activities:
Payments of loan and capital lease obligations	(1,431)	(1,119)
Issuance of common stock, net of issuance costs	224,072	7,142
Net cash provided by financing activities	222,641	6,023
Effect of exchange rates on cash and cash equivalents	493	(312)
Net increase (decrease) in cash and cash equivalents	25,253	(36,691)
Cash and cash equivalents at beginning of period	17,755	49,597
Cash and cash equivalents at end of period	$ 43,008	$ 12,906

Organization and Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2011

Organization and Summary of Significant Accounting Policies [Abstract]

Organization and Summary of Significant Accounting Policies

Note 1 — Organization and Summary of Significant Accounting Policies

Organization

We are a clinical-stage biopharmaceutical company headquartered in San Francisco, California and incorporated in Delaware. We are developing a pipeline of drug candidates that utilize our PEGylation and advanced polymer conjugate technology platforms designed to improve the benefits of drugs for patients.

Our development activities have required significant resources to date and are expected to continue to require significant resources. As a result, we expect to continue to incur substantial losses and negative cash flows from operations in the future. Historically, we have financed our operations primarily through cash from licensing, collaboration and manufacturing agreements and public and private placements of debt and equity securities. At September 30, 2011, we had approximately $458.0 million in cash, cash equivalents, and investments in marketable securities and $239.8 million in indebtedness, including $215.0 million in outstanding convertible subordinated notes due September 2012. We are exploring a number of alternatives to provide for the repayment of the convertible notes.

Basis of Presentation and Principles of Consolidation

Our consolidated financial statements include the financial position, results of operations and cash flows of our wholly-owned subsidiaries: Nektar Therapeutics (India) Private Limited (Nektar India) and Nektar Therapeutics UK Limited and Aerogen, Inc. All intercompany accounts and transactions have been eliminated in consolidation. On December 2, 2010, we completed the dissolution of Aerogen, Inc. and all remaining assets were transferred to Nektar Therapeutics.

We prepared our Condensed Consolidated Financial Statements following the requirements of the Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. generally accepted accounting principles (GAAP) for annual periods can be condensed or omitted. In the opinion of management, these financial statements include all normal and recurring adjustments that we consider necessary for the fair presentation of our financial position and operating results.

Our Condensed Consolidated Financial Statements are denominated in U.S. dollars. Accordingly, changes in exchange rates between the applicable foreign currency and the U.S. dollar will affect the translation of each foreign subsidiary’s financial results into U.S. dollars for purposes of reporting our consolidated financial results. Translation gains and losses are included in accumulated other comprehensive income in the stockholders’ equity section of the Condensed Consolidated Balance Sheets. To date, such cumulative currency translation adjustments have not been material to our consolidated financial position.

Revenue, expenses, assets, and liabilities can vary during each quarter of the year. The results and trends in these interim Condensed Consolidated Financial Statements may not be indicative of the results to be expected for the full year or any other periods.

The accompanying Condensed Consolidated Balance Sheet as of September 30, 2011, the Condensed Consolidated Statements of Operations for the three and nine months ended September 30, 2011 and 2010, and the Condensed Consolidated Statements of Cash Flows for the nine months ended September 30, 2011 and 2010 are unaudited. The Condensed Consolidated Balance Sheet data as of December 31, 2010 was derived from the audited consolidated financial statements which are included in our Annual Report on Form 10-K filed with the SEC on March 1, 2011. The information included in this quarterly report on Form 10-Q should be read in conjunction with the consolidated financial statements and the accompanying notes to those financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2010.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ materially from these estimates. On an ongoing basis, we evaluate our estimates, including those related to deferred revenue recognition periods, inventories, the impairment of investments and long-lived assets, contingencies, stock-based compensation, and litigation, amongst others. We base our estimates on historical experience and on other assumptions that management believes are reasonable under the circumstances. These estimates form the basis for making judgments about the carrying values of assets and liabilities when these values are not readily apparent from other sources.

Reclassifications

Certain items previously reported in specific financial statement captions have been reclassified to conform to the current period presentation. Such reclassifications do not impact previously reported revenue, operating loss or net loss or total assets, liabilities or stockholders’ equity.

Segment Information

We operate in one business segment which focuses on applying our technology platforms to improve the performance of established and novel medicines. We operate in one segment because our business offerings have similar economics and other characteristics, including the nature of products and manufacturing processes, types of customers, distribution methods and regulatory environment. We are comprehensively managed as one business segment by our Chief Executive Officer and his management team.

Significant Concentrations

Our customers are primarily pharmaceutical and biotechnology companies that are located in the U.S. and Europe. Our accounts receivable balance contains billed and unbilled trade receivables from product sales, royalties, and other amounts due under collaborative research, development and commercialization agreements. We provide for an allowance for doubtful accounts by reserving for specifically identified doubtful accounts. We generally do not require collateral from our customers. We regularly review our customers’ payment histories and associated credit risk. We have not experienced significant credit losses from our accounts receivable and therefore recorded no allowance for doubtful accounts at either September 30, 2011 or December 31, 2010.

We are dependent on our suppliers and contract manufacturers to provide raw materials, drugs and devices of appropriate quality and reliability and to meet applicable regulatory requirements. In certain cases, we rely on single sources of supply. Consequently, in the event that supplies are delayed or interrupted for any reason, our ability to develop and produce our products could be impaired, which could have a material adverse effect on our business, financial condition and results of operations.

Revenue

We enter into license and manufacturing agreements and collaborative research, development and commercialization arrangements with pharmaceutical and biotechnology partners that may involve multiple deliverables. Our arrangements may contain one or more of the following elements: upfront fees, contract research and development, milestone payments, manufacturing and supply, royalties, and license fees. Each deliverable in the arrangement is evaluated to determine whether it meets the criteria to be accounted for as a separate unit of accounting or whether it should be combined with other deliverables. Revenue is recognized for each element.

On January 1, 2011, we adopted on a prospective basis Accounting Standards Update (ASU) 2009-13, which amends the criteria to identify separate units of accounting within Subtopic 605-25, “Revenue Recognition-Multiple-Element Arrangements.” The adoption of the standard did not impact our financial position or results of operations as of and for the three and nine months ended September 30, 2011 as we did not enter into or materially modify any multiple-element arrangements during that period. However, the adoption of this standard may result in revenue recognition patterns for future agreements that are materially different from those recognized for our existing multiple-element arrangements.

Product sales and royalties

Product sales are primarily derived from cost-plus and fixed price manufacturing and supply agreements with our collaboration partners and revenue is recognized when there is persuasive evidence that an arrangement exists, delivery has occurred, the price is fixed or determinable, and collection is reasonably assured. We have not experienced any significant returns from our customers.

Generally, we are entitled to royalties from our partners based on their net sales of approved drugs. We recognize royalty revenue when the cash is received or when the royalty amount to be received is estimable and collection is reasonably assured.

License, collaboration and other

Upfront fees received for license and collaborative agreements entered into prior to January 1, 2011 are recognized ratably over our expected performance period under the arrangement. Management makes its best estimate of the period over which we expect to fulfill our performance obligations, which may include technology transfer assistance, clinical development activities, and manufacturing activities from development through the commercialization of the product. Given the uncertainties of these collaborative arrangements, significant judgment is required to determine the duration of the performance period.

On January 1, 2011, we elected to prospectively adopt ASU 2010-17, “Milestone Method of Revenue Recognition”. Under the milestone method, contingent consideration received from the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved, which we believe is more consistent with the substance of our performance under our various license and collaboration agreements. A milestone is defined as an event (i) that can only be achieved based in whole or in part on either the entity’s performance or on the occurrence of a specific outcome resulting from the entity’s performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved, and (iii) that would result in additional payments being due to the entity. A milestone is substantive if the consideration earned from the achievement of the milestone is consistent with our performance required to achieve the milestone or the increase in value to the collaboration resulting from our performance, relates solely to our past performance, and is reasonable relative to all of the other deliverables and payments within the arrangement.

Our license and collaboration agreements with our partners provide for payments to us upon the achievement of development milestones, such as the completion of clinical trials or regulatory submissions and approvals for drug candidates. As of January 1, 2011, our agreements with partners included potential future payments for development milestones totaling approximately $183.8 million. In addition, we are entitled to receive up to $235.0 million and $75.0 million of contingent payments related to NKTR-118 and NKTR-119, respectively, based on development events to be pursued and completed solely by AstraZeneca. Given the challenges inherent in developing and obtaining approval for pharmaceutical and biologic products, there was substantial uncertainty whether any such milestones would be achieved at the time these licensing and collaboration agreements were entered into. In addition, we evaluated whether the development milestones met the remaining criteria to be considered substantive. As a result of our analysis, we consider our development milestones to be substantive and, accordingly, we expect to recognize as revenue future payments received from such milestones as each milestone is achieved. This policy election may result in revenue recognition patterns for future milestones that are materially different from those recognized for milestones received prior to adoption. During the three and nine months ended September 30, 2011, we achieved two development milestones totaling $4.5 million from two of our collaboration agreements. Under the milestone method of revenue recognition, these substantive milestones were recognized in their entirety upon achievement in the three months ended September 30, 2011, whereas under our previous milestone revenue recognition policy, we would have recognized approximately $0.4 million related to such amounts during this period. As a result, in each of the three months and nine months ended September 30, 2011, this change in accounting policy results in increased revenues and a corresponding decrease to net loss of approximately $4.1 million and an increase of $0.04 per share.

Milestone payments received prior to January 1, 2011 have been deferred and are recognized as revenue ratably over the period of time from the achievement of the milestone to our estimated date on which the next milestone will be achieved. Management makes its best estimate of the period of time until the next milestone is expected to be reached. Final milestone payments were recorded and recognized upon achieving the respective milestone. The Company will continue to recognize milestones payments received prior to January 1, 2011 in this manner. As of September 30, 2011, deferred revenue from milestone payments received prior to January 1, 2011 is not significant.

Our license and collaboration agreements with certain partners also provide for contingent payments to us based solely upon the performance of the respective partner. For such contingent amounts we expect to recognize the payments as revenue when earned under the applicable contract, provided that collection is reasonably assured.

Our license and collaboration agreements with our partners also provide for payments to us upon the achievement of specified sales volumes of approved drugs. We consider these payments to be similar to royalty payments and we will recognize such sales-based payments upon achievement of such sales volumes, provided that collection is reasonably assured.

Income Taxes

We account for income taxes under the liability method, in which deferred tax assets and liabilities are determined based on differences between the financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Realization of deferred tax assets is dependent upon future earnings, the timing and amount of which are uncertain. We record a valuation allowance against deferred tax assets to reduce their carrying value to an amount that is more likely than not to be realized.

For the three months and nine months ended September 30, 2011 and 2010, we recorded an income tax provision for our Nektar India operations at an effective tax rate of approximately 33% and 34%, respectively. The U.S. Federal deferred tax assets generated from our net operating losses have been fully reserved as we believe it is not more likely than not that the benefit will be realized.

Organization and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2011
Organization and Summary of Significant Accounting Policies [Abstract]
Organization	We are a clinical-stage biopharmaceutical company headquartered in San Francisco, California and incorporated in Delaware. We are developing a pipeline of drug candidates that utilize our PEGylation and advanced polymer conjugate technology platforms designed to improve the benefits of drugs for patients. Our development activities have required significant resources to date and are expected to continue to require significant resources. As a result, we expect to continue to incur substantial losses and negative cash flows from operations in the future. Historically, we have financed our operations primarily through cash from licensing, collaboration and manufacturing agreements and public and private placements of debt and equity securities. At September 30, 2011, we had approximately $458.0 million in cash, cash equivalents, and investments in marketable securities and $239.8 million in indebtedness, including $215.0 million in outstanding convertible subordinated notes due September 2012. We are exploring a number of alternatives to provide for the repayment of the convertible notes.
Basis of Presentation and Principles of Consolidation	Our consolidated financial statements include the financial position, results of operations and cash flows of our wholly-owned subsidiaries: Nektar Therapeutics (India) Private Limited (Nektar India) and Nektar Therapeutics UK Limited and Aerogen, Inc. All intercompany accounts and transactions have been eliminated in consolidation. On December 2, 2010, we completed the dissolution of Aerogen, Inc. and all remaining assets were transferred to Nektar Therapeutics. We prepared our Condensed Consolidated Financial Statements following the requirements of the Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. generally accepted accounting principles (GAAP) for annual periods can be condensed or omitted. In the opinion of management, these financial statements include all normal and recurring adjustments that we consider necessary for the fair presentation of our financial position and operating results. Our Condensed Consolidated Financial Statements are denominated in U.S. dollars. Accordingly, changes in exchange rates between the applicable foreign currency and the U.S. dollar will affect the translation of each foreign subsidiary’s financial results into U.S. dollars for purposes of reporting our consolidated financial results. Translation gains and losses are included in accumulated other comprehensive income in the stockholders’ equity section of the Condensed Consolidated Balance Sheets. To date, such cumulative currency translation adjustments have not been material to our consolidated financial position. Revenue, expenses, assets, and liabilities can vary during each quarter of the year. The results and trends in these interim Condensed Consolidated Financial Statements may not be indicative of the results to be expected for the full year or any other periods. The accompanying Condensed Consolidated Balance Sheet as of September 30, 2011, the Condensed Consolidated Statements of Operations for the three and nine months ended September 30, 2011 and 2010, and the Condensed Consolidated Statements of Cash Flows for the nine months ended September 30, 2011 and 2010 are unaudited. The Condensed Consolidated Balance Sheet data as of December 31, 2010 was derived from the audited consolidated financial statements which are included in our Annual Report on Form 10-K filed with the SEC on March 1, 2011. The information included in this quarterly report on Form 10-Q should be read in conjunction with the consolidated financial statements and the accompanying notes to those financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2010.
Use of Estimates	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ materially from these estimates. On an ongoing basis, we evaluate our estimates, including those related to deferred revenue recognition periods, inventories, the impairment of investments and long-lived assets, contingencies, stock-based compensation, and litigation, amongst others. We base our estimates on historical experience and on other assumptions that management believes are reasonable under the circumstances. These estimates form the basis for making judgments about the carrying values of assets and liabilities when these values are not readily apparent from other sources.
Reclassifications	Certain items previously reported in specific financial statement captions have been reclassified to conform to the current period presentation. Such reclassifications do not impact previously reported revenue, operating loss or net loss or total assets, liabilities or stockholders’ equity.
Segment Information	We operate in one business segment which focuses on applying our technology platforms to improve the performance of established and novel medicines. We operate in one segment because our business offerings have similar economics and other characteristics, including the nature of products and manufacturing processes, types of customers, distribution methods and regulatory environment. We are comprehensively managed as one business segment by our Chief Executive Officer and his management team.
Significant Concentrations	Our customers are primarily pharmaceutical and biotechnology companies that are located in the U.S. and Europe. Our accounts receivable balance contains billed and unbilled trade receivables from product sales, royalties, and other amounts due under collaborative research, development and commercialization agreements. We provide for an allowance for doubtful accounts by reserving for specifically identified doubtful accounts. We generally do not require collateral from our customers. We regularly review our customers’ payment histories and associated credit risk. We have not experienced significant credit losses from our accounts receivable and therefore recorded no allowance for doubtful accounts at either September 30, 2011 or December 31, 2010. We are dependent on our suppliers and contract manufacturers to provide raw materials, drugs and devices of appropriate quality and reliability and to meet applicable regulatory requirements. In certain cases, we rely on single sources of supply. Consequently, in the event that supplies are delayed or interrupted for any reason, our ability to develop and produce our products could be impaired, which could have a material adverse effect on our business, financial condition and results of operations.
Revenue	Product sales are primarily derived from cost-plus and fixed price manufacturing and supply agreements with our collaboration partners and revenue is recognized when there is persuasive evidence that an arrangement exists, delivery has occurred, the price is fixed or determinable, and collection is reasonably assured. We have not experienced any significant returns from our customers. Generally, we are entitled to royalties from our partners based on their net sales of approved drugs. We recognize royalty revenue when the cash is received or when the royalty amount to be received is estimable and collection is reasonably assured. Upfront fees received for license and collaborative agreements entered into prior to January 1, 2011 are recognized ratably over our expected performance period under the arrangement. Management makes its best estimate of the period over which we expect to fulfill our performance obligations, which may include technology transfer assistance, clinical development activities, and manufacturing activities from development through the commercialization of the product. Given the uncertainties of these collaborative arrangements, significant judgment is required to determine the duration of the performance period. On January 1, 2011, we elected to prospectively adopt ASU 2010-17, “Milestone Method of Revenue Recognition”. Under the milestone method, contingent consideration received from the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved, which we believe is more consistent with the substance of our performance under our various license and collaboration agreements. A milestone is defined as an event (i) that can only be achieved based in whole or in part on either the entity’s performance or on the occurrence of a specific outcome resulting from the entity’s performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved, and (iii) that would result in additional payments being due to the entity. A milestone is substantive if the consideration earned from the achievement of the milestone is consistent with our performance required to achieve the milestone or the increase in value to the collaboration resulting from our performance, relates solely to our past performance, and is reasonable relative to all of the other deliverables and payments within the arrangement. Our license and collaboration agreements with our partners provide for payments to us upon the achievement of development milestones, such as the completion of clinical trials or regulatory submissions and approvals for drug candidates. As of January 1, 2011, our agreements with partners included potential future payments for development milestones totaling approximately $183.8 million. In addition, we are entitled to receive up to $235.0 million and $75.0 million of contingent payments related to NKTR-118 and NKTR-119, respectively, based on development events to be pursued and completed solely by AstraZeneca. Given the challenges inherent in developing and obtaining approval for pharmaceutical and biologic products, there was substantial uncertainty whether any such milestones would be achieved at the time these licensing and collaboration agreements were entered into. In addition, we evaluated whether the development milestones met the remaining criteria to be considered substantive. As a result of our analysis, we consider our development milestones to be substantive and, accordingly, we expect to recognize as revenue future payments received from such milestones as each milestone is achieved. This policy election may result in revenue recognition patterns for future milestones that are materially different from those recognized for milestones received prior to adoption. During the three and nine months ended September 30, 2011, we achieved two development milestones totaling $4.5 million from two of our collaboration agreements. Under the milestone method of revenue recognition, these substantive milestones were recognized in their entirety upon achievement in the three months ended September 30, 2011, whereas under our previous milestone revenue recognition policy, we would have recognized approximately $0.4 million related to such amounts during this period. As a result, in each of the three months and nine months ended September 30, 2011, this change in accounting policy results in increased revenues and a corresponding decrease to net loss of approximately $4.1 million and an increase of $0.04 per share. Milestone payments received prior to January 1, 2011 have been deferred and are recognized as revenue ratably over the period of time from the achievement of the milestone to our estimated date on which the next milestone will be achieved. Management makes its best estimate of the period of time until the next milestone is expected to be reached. Final milestone payments were recorded and recognized upon achieving the respective milestone. The Company will continue to recognize milestones payments received prior to January 1, 2011 in this manner. As of September 30, 2011, deferred revenue from milestone payments received prior to January 1, 2011 is not significant. Our license and collaboration agreements with certain partners also provide for contingent payments to us based solely upon the performance of the respective partner. For such contingent amounts we expect to recognize the payments as revenue when earned under the applicable contract, provided that collection is reasonably assured. Our license and collaboration agreements with our partners also provide for payments to us upon the achievement of specified sales volumes of approved drugs. We consider these payments to be similar to royalty payments and we will recognize such sales-based payments upon achievement of such sales volumes, provided that collection is reasonably assured.
Income Taxes	We account for income taxes under the liability method, in which deferred tax assets and liabilities are determined based on differences between the financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Realization of deferred tax assets is dependent upon future earnings, the timing and amount of which are uncertain. We record a valuation allowance against deferred tax assets to reduce their carrying value to an amount that is more likely than not to be realized. For the three months and nine months ended September 30, 2011 and 2010, we recorded an income tax provision for our Nektar India operations at an effective tax rate of approximately 33% and 34%, respectively. The U.S. Federal deferred tax assets generated from our net operating losses have been fully reserved as we believe it is not more likely than not that the benefit will be realized.

Organization and Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011 CollaborationAgreements Milestones	Sep. 30, 2010	Sep. 30, 2011 CollaborationAgreements Segments Milestones	Sep. 30, 2010	Dec. 31, 2010
Organization and Summary of Significant Accounting Policies (Textuals) [Abstract]
Cash and cash equivalents, and Investment in marketable securities	$ 458,000,000		$ 458,000,000
Indebtedness	239,800,000		239,800,000
Outstanding convertible subordinated notes	214,955,000		214,955,000		0
Convertible subordinated notes	0		0		214,955,000
Number of business segments			1
Allowance for doubtful accounts	0		0		0
Estimated potential future payments for development milestones					183,800,000
Number of development milestones achieved	2		2
Development milestones payments received upon achievement	4,500,000		4,500,000
Number of collaboration agreements from which development milestones achieved	2		2
Recognized revenue under previous milestone revenue recognition policy	400,000		400,000
Increase in revenue under milestone method of revenue recognition	4,100,000		4,100,000
Increase in per share under milestone method of revenue recognition	$ 0.04		$ 0.04
Effective income tax rate	33.00%	34.00%	33.00%	34.00%
NKTR-118 [Member]
Deferred Revenue Arrangement [Line Items]
Contingent payments receivable based on development events	235,000,000		235,000,000
NKTR-119 [Member]
Deferred Revenue Arrangement [Line Items]
Contingent payments receivable based on development events	$ 75,000,000		$ 75,000,000

Cash, Cash Equivalents, and Available-For-Sale Investments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Cash, cash equivalents, and available-for-sale investments
Cash and cash equivalents	$ 43,008	$ 17,755
Short-term investments	223,479	298,177
Long-term investments	191,478	0
Total cash, cash equivalents, and available-for-sale investments	$ 457,965	$ 315,932

Cash, Cash Equivalents, and Available-For-Sale Investments (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Cash, cash equivalents, and available-for-sale investments	$ 457,965	$ 315,932
Corporate notes and bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash, cash equivalents, and available-for-sale investments	342,278	190,527
U.S. corporate commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash, cash equivalents, and available-for-sale investments	49,941	82,361
Obligations of U.S. government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash, cash equivalents, and available-for-sale investments	22,738	25,289
Cash and money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash, cash equivalents, and available-for-sale investments	$ 43,008	$ 17,755

Cash, Cash Equivalents, and Available-For-Sale Investments (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Portfolio of available-for-sale investments
Less than one year	$ 223,479	$ 298,177
Greater than one year but less than two years	191,478	0
Total available-for-sale investments	$ 414,957	$ 298,177

Cash, Cash Equivalents, and Available-For-Sale Investments (Details 3) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Fair value assets measured on recurring basis
Cash	$ 732	$ 1,727
Cash, cash equivalents, and available-for-sale investments	457,965	315,932
Money market funds [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	42,276	16,028
Money market funds [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	42,276	16,028
Money market funds [Member] \| Level 2 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	0	0
Money market funds [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	0	0
U.S. corporate commercial paper [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	49,941	82,361
U.S. corporate commercial paper [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	0	0
U.S. corporate commercial paper [Member] \| Level 2 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	49,941	82,361
U.S. corporate commercial paper [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	0	0
Corporate notes and bonds [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	342,278	190,527
Corporate notes and bonds [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	0	0
Corporate notes and bonds [Member] \| Level 2 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	342,278	190,527
Corporate notes and bonds [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	0	0
Obligations of U.S. government agencies [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	22,738	25,289
Obligations of U.S. government agencies [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	0	0
Obligations of U.S. government agencies [Member] \| Level 2 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	22,738	25,289
Obligations of U.S. government agencies [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	0	0
Cash equivalents and available-for-sale investments [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	457,233	314,205
Cash equivalents and available-for-sale investments [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	42,276	16,028
Cash equivalents and available-for-sale investments [Member] \| Level 2 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	414,957	298,177
Cash equivalents and available-for-sale investments [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Cash, cash equivalents, and available-for-sale investments	$ 0	$ 0

Cash, Cash Equivalents, and Available-For-Sale Investments (Details Textuals)	9 Months Ended
	Sep. 30, 2011
Cash Cash Equivalents and Available For Sale Investments (Textuals) [Abstract]
Maximum maturity term for debt securities investment	two years or less
Weighted average maturity term for debt securities investment	One year or less

Inventory (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Inventory
Raw materials	$ 9,305	$ 6,101
Work-in-process	1,349	0
Finished goods	0	1,165
Total	$ 10,654	$ 7,266

Inventory (Details Textuals) (USD $) In Millions, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Inventory (Textuals) [Abstract]
Inventory reserves	$ 3.2	$ 4.0

Stockholders' Equity (Details Textuals) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2011
Stockholders' Equity (Textuals) [Abstract]
Common stock, shares issued	19,000,000
Value of common stock issued	$ 220.4
Legal and accounting fees, filing fees, and other offering expenses	$ 0.6

License and Collaboration Agreements (Details Textuals) (USD $)	3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended				9 Months Ended		3 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	12 Months Ended
	Sep. 30, 2011 Milestones CollaborationAgreements	Sep. 30, 2010	Sep. 30, 2011 CollaborationAgreements Milestones	Sep. 30, 2010	Sep. 30, 2011 NKTR-118 [Member]	Sep. 30, 2011 NKTR-119 [Member]	Sep. 30, 2011 AstraZeneca AB [Member] NKTR-118 and NKTR-119 [Member]	Sep. 30, 2010 AstraZeneca AB [Member] NKTR-118 and NKTR-119 [Member]	Sep. 30, 2011 AstraZeneca AB [Member] NKTR-118 and NKTR-119 [Member]	Sep. 30, 2010 AstraZeneca AB [Member] NKTR-118 and NKTR-119 [Member]	Sep. 30, 2011 AstraZeneca AB [Member] NKTR-118 [Member]	Sep. 30, 2011 AstraZeneca AB [Member] NKTR-119 [Member]	Sep. 30, 2011 Bayer Healthcare LLC [Member]	Sep. 30, 2011 F Hoffmann La Roche [Member]	Dec. 31, 2010 Amgen Inc [Member]	Sep. 30, 2011 Amgen Inc [Member]	Sep. 30, 2011 Other Partner [Member] CollaborationAgreements Milestones	Sep. 30, 2010 Other Partner [Member]	Sep. 30, 2011 Other Partner [Member]	Sep. 30, 2010 Other Partner [Member]	Dec. 31, 2009 Up-front Payment arrangement [Member] AstraZeneca AB [Member]	Dec. 31, 2007 Up-front Payment arrangement [Member] Bayer Healthcare LLC [Member]	Dec. 31, 2007 Performance milestone payments [Member] Bayer Healthcare LLC [Member]	Dec. 31, 2009 License option [Member] F Hoffmann La Roche [Member]
Deferred Revenue Arrangement [Line Items]
Deferred Revenue													$ 28,100,000	$ 21,800,000		$ 45,400,000
Received upfront payment															50,000,000						125,000,000	40,000,000	20,000,000	31,000,000
Development milestone payments receivable upon achievement of Milestone													60,000,000				4,500,000		4,500,000
Contingent payments receivable based on development events					235,000,000	75,000,000					235,000,000	75,000,000
Performance milestone used to reimburse clinical trial costs													10,000,000
License, collaboration and other	16,846,000	30,695,000	29,675,000	91,757,000			1,395,000	26,788,000	2,481,000	80,094,000							12,168,000	1,806,000	17,345,000	5,291,000
License fee payment receivable																	10,000,000		10,000,000
License fee receivable current																	5,000,000		5,000,000
License fee receivable in 2013																	3,000,000		3,000,000
License fee receivable in 2015																	2,000,000		2,000,000
Revenue recognized as contractual obligations completed			$ 5,000,000														$ 5,000,000
Number of collaboration agreements	2		2														2
Number of development milestones	2		2														2
License and Collaboration Agreements (Textuals) [Abstract]
Upfront Payment Amortization Period			15 months

Stock-Based Compensation (Details Textuals) (USD $)	3 Months Ended		9 Months Ended
Stock-Based Compensation (Details Textuals) (USD $)	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Stock Based Compensation (Textuals) [Abstract]
Granted stock options	331,480	560,320	2,723,445	5,035,475
Weighted average grant-date fair value of options granted	$ 2.79	$ 6.75	$ 5.30	$ 6.24
Stock issuances under equity compensation	121,705	142,257	909,181	992,680