Document and Entity Information (USD $)	6 Months Ended
Document and Entity Information (USD $)	Jun. 30, 2011	Aug. 01, 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	Jun. 30, 2011
Amendment Flag	false
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q2
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		114,418,913

Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 11,626	$ 17,755
Short-term investments	351,280	298,177
Accounts receivable	8,460	25,102
Inventory	9,797	7,266
Other current assets	7,932	5,679
Total current assets	389,095	353,979
Long-term investments	118,941	0
Property and equipment, net	85,381	89,773
Goodwill	76,501	76,501
Other assets	936	972
Total assets	670,854	521,225
Current liabilities:
Accounts payable	3,243	7,194
Accrued compensation	9,435	9,252
Accrued expenses	8,129	8,540
Accrued clinical trial expenses	13,832	12,144
Deferred revenue, current portion	19,867	20,584
Other current liabilities	6,768	6,394
Total current liabilities	61,274	64,108
Convertible subordinated notes	214,955	214,955
Capital lease obligations, less current portion	15,863	17,014
Deferred revenue, less current portion	117,931	124,763
Deferred gain	3,715	4,152
Other long-term liabilities	5,840	5,571
Total liabilities	419,578	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 June 30, 2011 and December 31, 2010	0	0
Common stock, $0.0001 par value; 300,000 authorized; 114,305 shares and 94,517 shares issued and outstanding at June 30, 2011 and December 31, 2010, respectively	11	9
Capital in excess of par value	1,587,461	1,354,232
Accumulated other comprehensive income	766	968
Accumulated deficit	(1,336,962)	(1,264,547)
Total stockholders' equity	251,276	90,662
Total liabilities and stockholders' equity	$ 670,854	$ 521,225

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Jun. 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	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000	300,000
Common stock, shares issued	114,305	94,517
Common stock, shares outstanding	114,305	94,517

Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Revenue:
Product sales and royalties	$ 11,008	$ 11,154	$ 15,801	$ 14,738
License, collaboration and other	6,323	31,409	12,829	61,062
Total revenue	17,331	42,563	28,630	75,800
Operating costs and expenses:
Cost of goods sold	8,140	4,889	11,403	9,185
Research and development	32,270	25,600	62,446	48,886
General and administrative	11,185	10,207	22,912	19,220
Total operating costs and expenses	51,595	40,696	96,761	77,291
Income (loss) from operations	(34,264)	1,867	(68,131)	(1,491)
Non-operating income (expense):
Interest income	529	393	961	856
Interest expense	(2,570)	(2,909)	(5,155)	(5,860)
Other income (expense), net	(16)	163	118	187
Total non-operating expense	(2,057)	(2,353)	(4,076)	(4,817)
Loss before provision for income taxes	(36,321)	(486)	(72,207)	(6,308)
Provision for income taxes	60	31	208	339
Net loss	$ (36,381)	$ (517)	$ (72,415)	$ (6,647)
Basic and diluted net loss per share	$ (0.32)	$ (0.01)	$ (0.65)	$ (0.07)
Weighted average shares outstanding used in computing basic and diluted net loss per share	114,153	94,065	111,430	93,849

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows from operating activities:
Net loss	$ (72,415)	$ (6,647)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	7,649	8,334
Stock-based compensation	9,682	8,105
Other non-cash transactions	620	(205)
Changes in operating assets and liabilities:
Accounts receivable	16,642	(4,645)
Inventory	(2,531)	(3,306)
Other assets	(2,191)	(136)
Accounts payable	(3,149)	2,183
Accrued compensation	183	(2,144)
Accrued expenses	2,371	1,012
Accrued clinical trial expenses	1,688	(818)
Deferred revenue	(7,549)	(55,120)
Other liabilities	(658)	(729)
Net cash used in operating activities	(49,658)	(54,116)
Cash flows from investing activities:
Purchases of investments	(509,681)	(218,275)
Sales of investments	180,478	8,197
Maturities of investments	156,962	241,256
Purchases of property and equipment	(6,845)	(8,796)
Net cash (used in) provided by investing activities	(179,086)	22,382
Cash flows from financing activities:
Payments of loan and capital lease obligations	(934)	(731)
Issuance of common stock, net of issuance costs	223,549	6,148
Net cash provided by financing activities	222,615	5,417
Effect of exchange rates on cash and cash equivalents	0	(36)
Net decrease in cash and cash equivalents	(6,129)	(26,353)
Cash and cash equivalents at beginning of period	17,755	49,597
Cash and cash equivalents at end of period	$ 11,626	$ 23,244

Organization and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 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. *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 June 30, 2011, the Condensed Consolidated Statements of Operations for the three and six months ended June 30, 2011 and 2010, and the Condensed Consolidated Statements of Cash Flows for the six months ended June 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, restructuring and 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 both June 30, 2011 and 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 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 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 six months ended June 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. 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. 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. The election to adopt the milestone method did not impact our financial position or results of operations as of and for the three and six months ended June 30, 2011. However, 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. 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 June 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 our partner. For such contingent payments we expect to recognize the payments as revenue when they are 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 recognize such sales-based payments upon achievement of the milestone, 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 six months ended June 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.

Cash, Cash Equivalents, and Available-For-Sale Investments

6 Months Ended

Jun. 30, 2011

Cash, Cash Equivalents, and Available-For-Sale Investments [Abstract]

Cash, Cash Equivalents, and Available-For-Sale Investments

Note 2 — Cash, Cash Equivalents, and Available-For-Sale Investments

Cash, cash equivalents, and available-for-sale investments are as follows (in thousands):


	Estimated Fair Value at
	June 30,		December 31,
	2011		2010
Cash and cash equivalents	$	11,626	$	17,755
Short-term investments		351,280		298,177
Long-term investments		118,941		—

Total cash, cash equivalents, and available-for-sale investments	$	481,847	$	315,932

Our portfolio of cash, cash equivalents, and available-for-sale investments includes (in thousands):


	Estimated Fair Value at
	June 30,		December 31,
	2011		2010
Corporate notes and bonds	$	360,536	$	190,527
U.S. corporate commercial paper		101,434		82,361
Obligations of U.S. government agencies		8,251		25,289
Cash and money market funds		11,626		17,755

Total cash, cash equivalents, and available-for-sale investments	$	481,847	$	315,932

The following table summarizes our portfolio of available-for-sale investments reported as short-term and long-term investments by contractual maturity (in thousands):


	Estimated Fair Value at
	June 30,		December 31,
	2011		2010
Less than one year	$	351,280	$	298,177
Greater than one year but less than two years		118,941		—

Total available-for-sale investments	$	470,221	$	298,177

We invest in liquid, high quality debt securities. Our investments in debt securities are subject to interest rate risk. To minimize the exposure due to an adverse shift in interest rates, we invest in securities with maturities of two years or less and maintain a weighted average maturity of one year or less. Investments in securities with maturities of less than one year are classified as short-term investments.

During the six months ended June 30, 2011 and 2010, we realized gains and losses of less than $0.1 million from sales of available-for-sale securities in each of the periods. The cost of securities sold is based on the specific identification method.

Gross unrealized gains and losses were not significant at June 30, 2011 and December 31, 2010. The gross unrealized losses were primarily due to changes in interest rates on fixed income securities. Based on our available cash and our expected operating cash requirements, we do not intend to sell these securities and it is more likely than not that we will not be required to sell these securities before we recover the amortized cost basis. Accordingly, we believe there are no other-than-temporary impairments on these securities and have not recorded a provision for impairment.

We use a market approach to value our Level 2 investments as described in the table below. The disclosed fair value related to our investments is based primarily on the reported fair values in our period-end brokerage statements. We independently validate these fair values using available market quotes and other information.

The following table represents the fair value hierarchy for our financial assets measured at fair value on a recurring basis as of June 30, 2011 and December 31, 2010 (in thousands):


	Level 1		Level 2		Level 3		Total
As of June 30, 2011:
Money market funds	$	10,594	$	—	$	—	$	10,594
U.S. corporate commercial paper		—		101,434		—		101,434
Corporate notes and bonds		—		360,536		—		360,536
Obligations of U.S. government agencies		—		8,251		—		8,251

Cash equivalents and available-for-sale investments	$	10,594	$	470,221	$	—	$	480,815
Cash								1,032

Cash, cash equivalents, and available-for-sale investments							$	481,847


As of December 31, 2010:
Money market funds	$	16,028	$	—	$	—	$	16,028
U.S. corporate commercial paper		—		82,361		—		82,361
Corporate notes and bonds		—		190,527		—		190,527
Obligations of U.S. government agencies		—		25,289		—		25,289

Cash equivalents and available-for-sale investments	$	16,028	$	298,177	$	—	$	314,205
Cash								1,727

Cash, cash equivalents, and available-for-sale investments							$	315,932


Level 1 —		Quoted prices in active markets for identical assets or liabilities.

Level 2 —		Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 —		Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

- Definition

This item represents the complete disclosure regarding the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the Company is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risk is are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References+ Details

Inventory

6 Months Ended

Jun. 30, 2011

Inventory [Abstract]

Inventory

Note 3—Inventory

Inventory consists of the following (in thousands):


	June 30,		December 31,
	2011		2010
Raw materials	$	8,985	$	6,101
Work-in-process		808		—
Finished goods		4		1,165

Total	$	9,797	$	7,266

Inventory is manufactured upon receipt of firm orders from our collaboration partners. Inventory includes direct materials, direct labor, and manufacturing overhead and is determined on a first-in, first-out basis. Inventory is stated at the lower of cost or market and is net of reserves of $2.9 million and $4.0 million as of June 30, 2011 and December 31, 2010, respectively. Reserves are determined using specific identification plus an estimated reserve for potential defective or excess inventory based on historical experience or projected usage.

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2011
Commitments and Contingencies [Abstract]
Commitments and Contingencies	Note 4—Commitments and Contingencies *Legal Matters* From time to time, we are involved in lawsuits, arbitrations, claims, investigations and proceedings, consisting of intellectual property, commercial, employment and other matters, which arise in the ordinary course of business. We make provisions for liabilities when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. Such provisions, if necessary, are reviewed at least quarterly and adjusted to reflect the impact of settlement negotiations, judicial and administrative rulings, advice of legal counsel, and other information and events pertaining to a particular case. Litigation is inherently unpredictable. If any unfavorable ruling were to occur in any specific period, there exists the possibility of a material adverse impact on the results of operations of that period or on our cash flows and liquidity. *Indemnifications in Connection with Commercial Agreements* As part of our collaboration agreements with our partners related to the license, development, manufacture and supply of drugs based on our proprietary technologies, we generally agree to defend, indemnify and hold harmless our partners from and against third party liabilities arising out of the agreement, including product liability (with respect to our activities) and infringement of intellectual property to the extent the intellectual property is developed by us and licensed to our partners. The term of these indemnification obligations is generally perpetual any time after execution of the agreement. There is generally no limitation on the potential amount of future payments we could be required to make under these indemnification obligations. As part of our pulmonary asset sale to Novartis that was effective as of December 31, 2008, we and Novartis made representations and warranties and entered into certain covenants and ancillary agreements which are supported by an indemnity obligation. In the event it were determined that we breached certain of the representations and warranties or covenants and agreements made by us in the transaction documents, we could incur an indemnification liability depending on the timing, nature, and amount of any such claims. To date we have not incurred costs to defend lawsuits or settle claims related to these indemnification obligations. If any of our indemnification obligations is triggered, we may incur substantial liabilities. Because the obligated amount under these agreements is not explicitly stated, the overall maximum amount of any such obligations cannot be reasonably estimated. No liabilities have been recorded for these obligations on our Condensed Consolidated Balance Sheets as of June 30, 2011 or December 31, 2010.

Stockholders' Equity	6 Months Ended
Stockholders' Equity	Jun. 30, 2011
Stockholders' Equity [Abstract]
Stockholders' Equity	Note 5— Stockholders’ Equity On January 24, 2011, we completed the issuance and sale of 19,000,000 shares of our common stock for proceeds to the Company of approximately $220.4 million. Additionally, we incurred approximately $0.6 million in legal and accounting fees, filing fees, and other offering expenses.

- Definition

Disclosures related to accounts comprising shareholders' equity, including other comprehensive income. Includes: (1) balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings; (2) accumulated balance for each classification of other comprehensive income and total amount of comprehensive income; (3) amount and nature of changes in separate accounts, including the number of shares authorized and outstanding, number of shares issued upon exercise and conversion, and for other comprehensive income, the adjustments for reclassifications to net income; (4) rights and privileges of each class of stock authorized; (5) basis of treasury stock, if other than cost, and amounts paid and accounting treatment for treasury stock purchased significantly in excess of market; (6) dividends paid or payable per share and in the aggregate for each class of stock for each period presented; (7) dividend restrictions and accumulated preferred dividends in arrears (in aggregate and per share amount); (8) retained earnings appropriations or restrictions, such as dividend restrictions; (9) impact of change in accounting principle, initial adoption of new accounting principle and correction of an error in previously issued financial statements; (10) shares held in trust for Employee Stock Ownership Plan (ESOP); (11) deferred compensation related to issuance of capital stock; (12) note received for issuance of stock; (13) unamortized discount on shares; (14) description, terms and number of warrants or rights outstanding; (15) shares under subscription and subscription receivables; effective date of new retained earnings after quasi-reorganization and deficit eliminated by quasi-reorganization and, for a period of at least ten years after the effective date, the point in time from which the new retained dates; and (16) retroactive effective of subsequent change in capital structure.

+ References+ Details

License and Collaboration Agreements

6 Months Ended

Jun. 30, 2011

License and Collaboration Agreements [Abstract]

License and Collaboration Agreements

Note 6—License and Collaboration Agreements

We have entered into various license and manufacturing agreements and collaborative research, development and commercialization agreements with pharmaceutical and biotechnology companies. Under these arrangements, we are entitled to receive license fees, upfront payments, milestone payments when and if certain development or regulatory milestones are achieved, royalties, sales milestones, payment for the manufacture and supply of certain drug materials, and/or reimbursement for research and development activities. All of our research, development and commercialization agreements are generally cancelable by our partners without significant financial penalty to the partner. Our costs of performing these services are included in research and development expense in the accompanying Condensed Consolidated Statements of Operations.

In accordance with these agreements, we recorded license, collaboration and other revenue as follows (in thousands):


		Three months ended				Six months ended
		June 30,				June 30,
Partner	Drug or Drug Candidate	2011		2010		2011		2010
F. Hoffmann- LaRoche	PEGASYS^®	$	1,283	$	1,283	$	2,566	$	2,566
Amgen, Inc.	Neulasta^®		1,250		—		2,500		—
Bayer Healthcare LLC	BAY41-6551 (Amikacin Inhale)		750		818		1,500		1,705
AstraZeneca AB	NKTR-118 and NKTR-119		845		27,579		1,086		53,306
Other			2,195		1,729		5,177		3,485


License, collaboration, and other revenue		$	6,323	$	31,409	$	12,829	$	61,062

F. Hoffmann-LaRoche Ltd and Hoffmann-LaRoche Inc.

PEGASYS^®

In February 1997, we entered into a license, manufacturing and supply agreement with F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. (Roche), under which we granted Roche a worldwide, exclusive license to use certain PEGylation materials in the manufacture of PEGASYS. As a result of Roche exercising a license extension option in December 2009, Roche has the right to manufacture all of its requirements for our proprietary PEGylation materials for PEGASYS and we will perform additional manufacturing, if any, only on an as-requested basis. In connection with Roche’s exercise of the license option extension in December 2009, we received a payment of $31.0 million. As of June 30, 2011, we have deferred revenue of approximately $23.1 million, which we expect to amortize through December 2015, which is the period through which we are required to provide back-up manufacturing and supply services on an as-requested basis.

Amgen, Inc.

Neulasta^®

On October 29, 2010, we amended and restated an existing supply and license agreement by entering into a supply, dedicated suite and manufacturing guarantee agreement (the amended and restated agreement) and a license agreement with Amgen Inc. and Amgen Manufacturing, Limited (together referred to as Amgen). Under the terms of the amended and restated agreement, we guarantee the manufacture and supply of our proprietary PEGylation materials (Polymer Materials) to Amgen in an existing manufacturing suite to be used exclusively for the manufacture of Polymer Materials for Amgen (the Manufacturing Suite) in our manufacturing facility in Huntsville, Alabama (Facility). This supply arrangement is on a non-exclusive basis (other than the use of the Manufacturing Suite and certain equipment) whereby Nektar is free to manufacture and supply the Polymer Materials to any other third party and Amgen is free to procure the Polymer Materials from any other third party. Under the terms of the amended and restated agreement, we received a $50.0 million payment in the fourth quarter of 2010 in return for our guaranteeing the supply of certain quantities of Polymer Materials to Amgen including without limitation the Additional Rights described below and manufacturing fees that are calculated based on fixed and variable components applicable to the Polymer Materials ordered by Amgen and delivered by us. Amgen has no minimum purchase commitments. If quantities of the Polymer Materials ordered by Amgen exceed specified quantities, significant additional payments become payable to us in return for our guaranteeing the supply of additional quantities of the Polymer Materials.

The term of the amended and restated agreement ends on October 29, 2020. In the event we become subject to a bankruptcy or insolvency proceeding, we cease to own or control the Facility, we fail to manufacture and supply or certain other events, Amgen or its designated third party will have the right to elect, among certain other options, to take title to the dedicated equipment and access the Facility to operate the Manufacturing Suite solely for the purpose of manufacturing the Polymer Materials (the Additional Rights). Amgen may terminate the amended and restated agreement for convenience or due to an uncured material default by us.

As of June 30, 2011, we have deferred revenue of approximately $46.7 million, which we expect to amortize through October 2020, the estimated end of our obligations under the amended and restated agreement.

Bayer Healthcare LLC

BAY41-6551 (Amikacin Inhale)

On August 1, 2007, we entered into a co-development, license and co-promotion agreement with Bayer Healthcare LLC (Bayer) to develop a specially-formulated inhaled Amikacin. We are responsible for development and manufacturing and supply of the nebulizer device included in the Amikacin product. Bayer is responsible for most future clinical development and commercialization costs, all activities to support worldwide regulatory filings, approvals and related activities, further development of Amikacin Inhale and final product packaging and distribution. We received an upfront payment of $40.0 million in 2007 and performance milestone payments of $20.0 million, of which $10.0 million will be used to reimburse Bayer for Phase 3 clinical trial costs. We are entitled to $60.0 million of development milestones upon achievement of certain development objectives, sales milestones upon achievement of annual sales targets, and royalties based on annual worldwide net sales of Amikacin Inhale. As of June 30, 2011, we have deferred revenue of approximately $29.0 million, which we expect to amortize through July 2021, the estimated end of our obligations under this agreement.

AstraZeneca AB

NKTR-118 and NKTR-119

On September 20, 2009, we entered into a License Agreement with AstraZeneca AB, a Swedish corporation (AstraZeneca), under which we granted AstraZeneca a worldwide, exclusive, perpetual, royalty-bearing, and sublicensable license under our patents and other intellectual property to develop, sell and otherwise commercially exploit NKTR-118 and NKTR-119. AstraZeneca is responsible for all costs associated with research, development and commercialization and will control drug development and commercialization decisions for NKTR-118 and NKTR-119. Under the terms of the agreement, AstraZeneca paid us an upfront payment of $125.0 million, which we received in the fourth quarter of 2009. As of December 31, 2010, we completed our obligations under the license agreement and related manufacturing technology transfer agreement. The upfront payment was amortized over approximately 15 months beginning in October 2009 in accordance with our performance obligation period and was fully recognized as of December 31, 2010. We are also entitled 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, sales milestones, and royalties based on annual worldwide net sales of NTKR-118 and NKTR-119 products.

Stock-Based Compensation

6 Months Ended

Jun. 30, 2011

Stock-Based Compensation [Abstract]

Stock-Based Compensation

Note 7—Stock-Based Compensation

Total stock-based compensation cost was recorded in our Condensed Consolidated Financial Statements as follows (in thousands):


	Three months ended				Six months ended
	June 30,				June 30,
	2011		2010		2011		2010
Cost of goods sold	$	330	$	229	$	662	$	435
Research and development expense		2,120		1,734		4,089		3,301
General and administrative expense		2,430		2,398		4,931		4,369

Total stock-based compensation	$	4,880	$	4,361	$	9,682	$	8,105

During the three months ended June 30, 2011 and 2010, we granted 263,910 and 718,230 stock options, respectively. The weighted average grant-date fair value of options granted during the three months ended June 30, 2011 and 2010 was $4.90 per share and $7.34 per share, respectively.

During the six months ended June 30, 2011 and 2010, we granted 2,391,965 and 4,475,155 stock options, respectively. The weighted average grant-date fair value of options granted during the six months ended June 30, 2011 and 2010 was $5.65 per share and $6.17 per share, respectively.

As a result of stock issuances under our equity compensation plans, during the three months ended June 30, 2011 and 2010, we issued 281,776 and 212,299 common shares, respectively, and during the six months ended June 30, 2011 and 2010, we issued 787,476 and 850,423 common shares, respectively.

Net Loss Per Share

6 Months Ended

Jun. 30, 2011

Net Loss Per Share [Abstract]

Net Loss Per Share

Note 8—Net Loss Per Share

Basic net loss per share is calculated based on the weighted-average number of common shares outstanding during the periods presented. For all periods presented in the accompanying Condensed Consolidated Statements of Operations, the net loss available to common stockholders is equal to the reported net loss. Basic and diluted net loss per share are the same due to our historical net losses and the requirement to exclude potentially dilutive securities which would have an anti-dilutive effect on net loss per share. The weighted average of these potentially dilutive securities has been excluded from the diluted net loss per share calculation and is as follows (in thousands):


	Three months ended				Six months ended
	June 30,				June 30,
	2011		2010		2011		2010
Convertible subordinated notes		9,989		9,989		9,989		9,989
Stock options		11,620		9,358		11,308		8,971

Total		21,609		19,347		21,297		18,960

Organization and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2011
Organization and Summary of Significant Accounting Policies (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.
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 June 30, 2011, the Condensed Consolidated Statements of Operations for the three and six months ended June 30, 2011 and 2010, and the Condensed Consolidated Statements of Cash Flows for the six months ended June 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, restructuring and 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 both June 30, 2011 and 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 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 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 six months ended June 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. 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. 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. The election to adopt the milestone method did not impact our financial position or results of operations as of and for the three and six months ended June 30, 2011. However, 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. 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 June 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 our partner. For such contingent payments we expect to recognize the payments as revenue when they are 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 recognize such sales-based payments upon achievement of the milestone, 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 six months ended June 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.

- Definition

Describes an entity's accounting policy regarding (1) the principles it follows in consolidating or combining the separate financial statements, including the principles followed in determining the inclusion or exclusion of subsidiaries or other entities in the consolidated or combined financial statements and (2) its treatment of interests (for example common stock, a partnership interest or other means of exerting influence) in other entities, for example consolidation or use of the equity or cost methods of accounting. An entity also may describe its accounting treatment for intercompany accounts and transactions, noncontrolling interest, and the income statement treatment in consolidation for issuances of stock by a subsidiary.

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Cash, Cash Equivalents, and Available-For-Sale Investments (Tables)

6 Months Ended

Jun. 30, 2011

Cash, Cash Equivalents, and Available-For-Sale Investments (Tables) [Abstract]

Cash, cash equivalents, and available-for-sale investments


	Estimated Fair Value at
	June 30,		December 31,
	2011		2010
Cash and cash equivalents	$	11,626	$	17,755
Short-term investments		351,280		298,177
Long-term investments		118,941		—

Total cash, cash equivalents, and available-for-sale investments	$	481,847	$	315,932

Portfolio of cash, cash equivalents, and available-for-sale investments


	Estimated Fair Value at
	June 30,		December 31,
	2011		2010
Corporate notes and bonds	$	360,536	$	190,527
U.S. corporate commercial paper		101,434		82,361
Obligations of U.S. government agencies		8,251		25,289
Cash and money market funds		11,626		17,755

Total cash, cash equivalents, and available-for-sale investments	$	481,847	$	315,932

Portfolio of available-for-sale investments


	Estimated Fair Value at
	June 30,		December 31,
	2011		2010
Less than one year	$	351,280	$	298,177
Greater than one year but less than two years		118,941		—

Total available-for-sale investments	$	470,221	$	298,177

Financial assets measured at fair value on a recurring basis


	Level 1		Level 2		Level 3		Total
As of June 30, 2011:
Money market funds	$	10,594	$	—	$	—	$	10,594
U.S. corporate commercial paper		—		101,434		—		101,434
Corporate notes and bonds		—		360,536		—		360,536
Obligations of U.S. government agencies		—		8,251		—		8,251

Cash equivalents and available-for-sale investments	$	10,594	$	470,221	$	—	$	480,815
Cash								1,032

Cash, cash equivalents, and available-for-sale investments							$	481,847


As of December 31, 2010:
Money market funds	$	16,028	$	—	$	—	$	16,028
U.S. corporate commercial paper		—		82,361		—		82,361
Corporate notes and bonds		—		190,527		—		190,527
Obligations of U.S. government agencies		—		25,289		—		25,289

Cash equivalents and available-for-sale investments	$	16,028	$	298,177	$	—	$	314,205
Cash								1,727

Cash, cash equivalents, and available-for-sale investments							$	315,932


Level 1 —		Quoted prices in active markets for identical assets or liabilities.

Level 2 —		Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 —		Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

- Definition

This item represents the entire disclosure related to Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2011

Stock-Based Compensation (Tables) [Abstract]

Total stock-based compensation expense


	Three months ended				Six months ended
	June 30,				June 30,
	2011		2010		2011		2010
Cost of goods sold	$	330	$	229	$	662	$	435
Research and development expense		2,120		1,734		4,089		3,301
General and administrative expense		2,430		2,398		4,931		4,369

Total stock-based compensation	$	4,880	$	4,361	$	9,682	$	8,105

Organization and Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Organization and Summary of Significant Accounting Policies (Textuals) [Abstract]
Estimated potential future payments for development milestones					$ 183,800,000
Effective income tax rate	33.00%	34.00%	33.00%	34.00%
Allowance for doubtful accounts	$ 0		$ 0		$ 0

Cash, Cash Equivalents, and Available-For-Sale Investments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Cash, cash equivalents, and available-for-sale investments
Cash and cash equivalents	$ 11,626	$ 17,755
Short-term investments	351,280	298,177
Long-term investments	118,941	0
Total cash, cash equivalents, and available-for-sale investments	$ 481,847	$ 315,932

- Definition

Investments in debt and equity securities which are categorized neither as trading securities nor held-to-maturity securities and which are intended be sold or mature within one year from the balance sheet date or the normal operating cycle, whichever is longer. Such securities are reported at fair value; unrealized gains and losses related to Available-for-sale securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain or loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.

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Cash, Cash Equivalents, and Available-For-Sale Investments (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Portfolio of available-for-sale investments
Less than one year	$ 351,280	$ 298,177
Greater than one year but less than two years	118,941	0
Total available-for-sale investments	$ 470,221	$ 298,177

- Definition

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading. Such securities are reported at fair value, with unrealized gains and losses excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain or loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.

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- Definition

+ References+ Details

Inventory (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Inventory [Abstract]
Raw materials	$ 8,985	$ 6,101
Work-in-process	808	0
Finished goods	4	1,165
Total	$ 9,797	$ 7,266

Inventory (Details Textuals) (USD $) In Millions, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Inventory (Textuals) [Abstract]
Inventory reserves	$ 2.9	$ 4.0

Stockholders' Equity (Details Textuals) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 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) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
License, collaboration, and other revenue
License, collaboration and other	$ 6,323	$ 31,409	$ 12,829	$ 61,062
Other Partner [Member]
License, collaboration, and other revenue
License, collaboration and other	2,195	1,729	5,177	3,485
BAY41-6651 (Amikacin Inhale) [Member] \| Bayer Healthcare LLC [Member]
License, collaboration, and other revenue
License, collaboration and other	750	818	1,500	1,705
NKTR-118 and NKTR-119 [Member] \| AstraZeneca AB [Member]
License, collaboration, and other revenue
License, collaboration and other	845	27,579	1,086	53,306
Pegasys [Member] \| F Hoffmann La Roche [Member]
License, collaboration, and other revenue
License, collaboration and other	1,283	1,283	2,566	2,566
Neulasta [Member] \| Amgen Inc [Member]
License, collaboration, and other revenue
License, collaboration and other	$ 1,250	$ 0	$ 2,500	$ 0

License and Collaboration Agreements (Details Textuals) (USD $) In Millions, unless otherwise specified				6 Months Ended		3 Months Ended		3 Months Ended	12 Months Ended
	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]	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, 2008 Performance milestone payments [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]
License and Collaboration Agreements (Textuals) [Abstract]
Received upfront payment						$ 50.0		$ 125.0	$ 40.0	$ 10.0	$ 10.0	$ 31.0
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

Stock-Based Compensation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Total stock-based compensation expense
Total stock-based compensation	$ 4,880	$ 4,361	$ 9,682	$ 8,105
Cost of goods sold [Member]
Total stock-based compensation expense
Total stock-based compensation	330	229	662	435
Research and development expense [Member]
Total stock-based compensation expense
Total stock-based compensation	2,120	1,734	4,089	3,301
General and administrative expense [Member]
Total stock-based compensation expense
Total stock-based compensation	$ 2,430	$ 2,398	$ 4,931	$ 4,369

Stock-Based Compensation (Details Textuals) (USD $)	3 Months Ended		6 Months Ended
Stock-Based Compensation (Details Textuals) (USD $)	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Stock Based Compensation (Textuals) [Abstract]
Granted stock options	263,910	718,230	2,391,965	4,475,155
Weighted average grant-date fair value of options granted	$ 4.90	$ 7.34	$ 5.65	$ 6.17
Stock issuances under equity compensation	281,776	212,299	787,476	850,423

Net Loss Per Share (Details) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Antidilutive securities excluded from computation of earnings per share
Total	21,609	19,347	21,297	18,960
Convertible subordinated notes [Member]
Antidilutive securities excluded from computation of earnings per share
Total	9,989	9,989	9,989	9,989
Stock options [Member]
Antidilutive securities excluded from computation of earnings per share
Total	11,620	9,358	11,308	8,971

Cash, Cash Equivalents, and Available-For-Sale Investments (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Total cash, cash equivalents, and available-for-sale investments	$ 481,847	$ 315,932
Corporate notes and bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash, cash equivalents, and available-for-sale investments	360,536	190,527
U.S. corporate commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash, cash equivalents, and available-for-sale investments	101,434	82,361
Obligations of U.S. government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash, cash equivalents, and available-for-sale investments	8,251	25,289
Cash and money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash, cash equivalents, and available-for-sale investments	$ 11,626	$ 17,755

Cash, Cash Equivalents, and Available-For-Sale Investments (Details 3) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Fair value assets measured on recurring basis
Cash	$ 1,032	$ 1,727
Total cash, cash equivalents, and available-for-sale investments	481,847	315,932
Corporate notes and bonds [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	360,536	190,527
Corporate notes and bonds [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Total 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
Total cash, cash equivalents, and available-for-sale investments	360,536	190,527
Corporate notes and bonds [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	0	0
U.S. corporate commercial paper [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	101,434	82,361
U.S. corporate commercial paper [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Total 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
Total cash, cash equivalents, and available-for-sale investments	101,434	82,361
U.S. corporate commercial paper [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	0	0
Obligations of U.S. government agencies [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	8,251	25,289
Obligations of U.S. government agencies [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Total 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
Total cash, cash equivalents, and available-for-sale investments	8,251	25,289
Obligations of U.S. government agencies [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	0	0
Money market funds [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	10,594	16,028
Money market funds [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	10,594	16,028
Money market funds [Member] \| Level 2 [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	0	0
Money market funds [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Total 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
Total cash, cash equivalents, and available-for-sale investments	480,815	314,205
Cash equivalents and available-for-sale investments [Member] \| Level 1 [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	10,594	16,028
Cash equivalents and available-for-sale investments [Member] \| Level 2 [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	470,221	298,177
Cash equivalents and available-for-sale investments [Member] \| Level 3 [Member]
Fair value assets measured on recurring basis
Total cash, cash equivalents, and available-for-sale investments	$ 0	$ 0

Cash, Cash Equivalents, and Available-For-Sale Investments (Details Textuals)	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash Cash Equivalents and Available For Sale Investments (Textuals) [Abstract]
Realized gains and losses from sales of available-for-sale securities	less than $0.1 million	less than $0.1 million
Maturity term for debt securities investment	two years or less

Commitments and Contingencies (Details Textuals) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Commitments and Contingencies (Textuals) [Abstract]
Liabilities related to indemnification obligations	$ 0	$ 0