Document and Entity Information (USD $)	12 Months Ended
Document and Entity Information (USD $)	Dec. 31, 2014	Feb. 20, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2014
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	NKTR
Entity Registrant Name	NEKTAR THERAPEUTICS
Entity Central Index Key	0000906709
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		131,381,612
Entity Public Float			$ 1,625,943,780

Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 12,365	$ 39,067
Restricted cash	25,000
Short-term investments	225,459	197,959
Accounts receivable, net of allowance of nil at December 31, 2014 and 2013	3,607	2,229
Inventory	12,952	13,452
Other current assets	8,817	5,175
Total current assets	288,200	257,882
Restricted cash		25,000
Property, plant and equipment, net	70,368	66,974
Goodwill	76,501	76,501
Other assets	6,552	8,170
Total assets	441,621	434,527
Current liabilities:
Accounts payable	2,703	9,115
Accrued compensation	5,749	14,254
Accrued expenses	6,418	6,243
Accrued clinical trial expenses	7,708	16,905
Interest payable	6,917	6,917
Capital lease obligations, current portion	4,512	3,536
Deferred revenue, current portion	24,473	23,664
Liability related to the sale of future royalties, current portion		7,000
Other current liabilities	5,567	10,587
Total current liabilities	64,047	98,221
Senior secured notes	125,000	125,000
Capital lease obligations, less current portion	4,139	8,049
Liability related to receipt of refundable milestone payment		70,000
Liability related to the sale of future royalties, less current portion	120,471	121,520
Deferred revenue, less current portion	76,911	82,384
Other long-term liabilities	14,721	19,256
Total liabilities	405,289	524,430
Commitments and contingencies
Stockholders' equity (deficit):
Preferred stock, $0.0001 par value; 10,000 shares authorized, no shares designated, issued or outstanding at December 31, 2014 and 2013, respectively
Common stock, $0.0001 par value; 300,000 authorized; 131,216 shares and 116,494 shares issued and outstanding at December 31, 2014 and 2013, respectively	13	11
Capital in excess of par value	1,824,195	1,643,660
Accumulated other comprehensive loss	(1,567)	(1,181)
Accumulated deficit	(1,786,309)	(1,732,393)
Total stockholders' equity (deficit)	36,332	(89,903)
Total liabilities and stockholders' equity (deficit)	$ 441,621	$ 434,527

Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Allowance for accounts receivable	$ 0	$ 0
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares designated	0	0
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	131,216	116,494
Common stock, shares outstanding	131,216	116,494

Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue:
Product sales	$ 25,152	$ 44,846	$ 35,399
Royalty revenue	329	1,148	4,874
Non-cash royalty revenue related to sale of future royalties	21,937	22,055	10,791
License, collaboration and other revenue	153,289	80,872	30,127
Total revenue	200,707	148,921	81,191
Operating costs and expenses:
Cost of goods sold	28,533	38,509	30,428
Research and development	147,734	190,010	148,675
General and administrative	40,925	40,532	41,614
Impairment of long-lived assets			1,675
Total operating costs and expenses	217,192	269,051	222,392
Loss from operations	(16,485)	(120,130)	(141,201)
Non-operating income (expense):
Interest expense	(17,869)	(18,453)	(15,489)
Non-cash interest expense on liability related to sale of future royalties	(20,888)	(22,309)	(18,057)
Interest and other income (expense), net	814	1,124	3,298
Total non-operating expense, net	(37,943)	(39,638)	(30,248)
Loss before (benefit) provision for income taxes	(54,428)	(159,768)	(171,449)
(Benefit) provision for income taxes	(512)	2,245	406
Net loss	$ (53,916)	$ (162,013)	$ (171,855)
Basic and diluted net loss per share	$ (0.42)	$ (1.40)	$ (1.50)
Weighted average shares outstanding used in computing basic and diluted net loss per share	126,873	115,732	114,820

Consolidated Statements of Comprehensive Loss (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net loss	$ (53,916)	$ (162,013)	$ (171,855)
Other comprehensive income (loss):
Net unrealized (loss) gain on available-for-sale investments	(95)	(268)	1,206
Income tax provision (benefit) on unrealized gain on available-for-sale investments		470	(470)
Net foreign currency translation (loss) gain	(291)	(1,026)	10
Other comprehensive income (loss), net of tax	(386)	(824)	746
Comprehensive loss	$ (54,302)	$ (162,837)	$ (171,109)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Consolidated Statements of Stockholders' Equity (Deficit) (USD $) In Thousands	Total	Common Shares [Member]	Capital in Excess of Par Value [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2011	$ 197,811	$ 11	$ 1,597,428	$ (1,103)	$ (1,398,525)
Beginning Balance, Shares at Dec. 31, 2011		114,485
Shares issued under equity compensation plans	4,117		4,117
Shares issued under equity compensation plans, Shares		774
Stock-based compensation	16,199		16,199
Other comprehensive income/(loss)	746			746
Net loss	(171,855)				(171,855)
Ending Balance at Dec. 31, 2012	47,018	11	1,617,744	(357)	(1,570,380)
Ending Balance, Shares at Dec. 31, 2012		115,259
Shares issued under equity compensation plans	8,208		8,208
Shares issued under equity compensation plans, Shares		1,235
Stock-based compensation	17,708		17,708
Other comprehensive income/(loss)	(824)			(824)
Net loss	(162,013)				(162,013)
Ending Balance at Dec. 31, 2013	(89,903)	11	1,643,660	(1,181)	(1,732,393)
Ending Balance, Shares at Dec. 31, 2013		116,494
Sale of common stock, net of issuance costs of $617	116,536	1	116,535
Sale of common stock, Shares		9,775
Shares issued under equity compensation plans	46,984	1	46,983
Shares issued under equity compensation plans, Shares		4,947
Stock-based compensation	17,017		17,017
Other comprehensive income/(loss)	(386)			(386)
Net loss	(53,916)				(53,916)
Ending Balance at Dec. 31, 2014	$ 36,332	$ 13	$ 1,824,195	$ (1,567)	$ (1,786,309)
Ending Balance, Shares at Dec. 31, 2014		131,216

- Definition

This element represents the amount of recognized equity-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Alternate captions include the words "stock-based compensation".

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- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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- Definition

Value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of stock value of such awards forfeited. Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net loss	$ (53,916)	$ (162,013)	$ (171,855)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash royalty revenue related to sale of future royalties	(21,937)	(22,055)	(10,791)
Non-cash interest expense on liability related to sale of future royalties	20,888	22,309	18,057
Stock-based compensation	17,017	17,708	16,199
Depreciation and amortization	12,927	14,275	14,508
Other non-cash transactions	(560)	664	2,520
Changes in assets and liabilities:
Accounts receivable, net	(1,378)	3,576	(867)
Inventory	500	4,817	(5,613)
Other assets	(3,294)	6,423	6,031
Accounts payable	(6,359)	6,199	(122)
Accrued compensation	(8,505)	5,481	(4,034)
Accrued expenses	273	(1,915)	1,495
Accrued clinical trial expenses	(9,197)	(595)	5,547
Interest payable		(166)	5,278
Deferred revenue	(4,664)	(12,399)	(9,384)
Liability related to receipt of refundable milestone payment	(70,000)	70,000
Other liabilities	(13,801)	9,164	3,275
Net cash used in operating activities	(142,006)	(38,527)	(129,756)
Cash flows from investing activities:
Maturities of investments	247,995	319,181	307,887
Purchases of investments	(297,251)	(268,068)	(164,662)
Sales of investments	21,661	2,887	5,378
Restricted cash			(25,000)
Purchases of property, plant and equipment	(9,976)	(4,091)	(10,583)
Net cash (used in) provided by investing activities	(37,571)	49,909	113,020
Cash flows from financing activities:
Payment of capital lease obligations	(3,536)	(2,992)	(2,437)
Issuance of common stock, net of issuance costs	116,536
(Repayment of) proceeds from sale of future royalties, net of $4.4 million of transaction costs in 2012	(7,000)	(3,000)	119,588
Proceeds from issuance of senior secured notes, net of $4.5 million of issuance costs			77,940
Repayment of convertible subordinated notes			(172,407)
Proceeds from shares issued under equity compensation plans	46,984	8,208	4,117
Net cash provided by financing activities	152,984	2,216	26,801
Effect of exchange rates on cash and cash equivalents	(109)	32	60
Net (decrease) increase in cash and cash equivalents	(26,702)	13,630	10,125
Cash and cash equivalents at beginning of year	39,067	25,437	15,312
Cash and cash equivalents at end of year	12,365	39,067	25,437
Supplemental disclosure of cash flow information:
Cash paid for interest	17,445	17,590	9,620
Cash paid for income taxes	964	1,014	1,021
Supplemental schedule of non-cash investing and financing activities:
Property and equipment acquired through capital leases and other financing	5,231	2,000
Retirement of convertible subordinated notes in exchange for senior secured notes			$ 42,548

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	Note 1 — Organization and Summary of Significant Accounting Policies *Organization* We are a 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 with the objective to improve the benefits of drugs for patients. Our research and development activities have required significant ongoing investment to date and are expected to continue to require significant investment. As a result, we expect to continue to incur substantial losses and negative cash flows from operations in the future. We have financed our operations primarily through cash generated from licensing, collaboration and manufacturing agreements and financing transactions. At December 31, 2014, we had approximately $262.8 million in cash and investments in marketable securities, of which $25.0 million was restricted in relation to our 12% senior secured notes, and $151.8 million in indebtedness. The indebtedness includes $125.0 million in aggregate principal amount of 12.0% senior secured notes due July 15, 2017, but excludes our long-term liability relating to the sale of future royalties. As is further described in Note 7, this royalty obligation liability will not be settled in cash. *Basis of Presentation, Principles of Consolidation and Use of Estimates* Our consolidated financial statements include the financial position, results of operations and cash flows of our wholly-owned subsidiaries: Nektar Therapeutics (India) Private Limited and Nektar Therapeutics UK, Ltd. (Nektar UK). All intercompany accounts and transactions have been eliminated in consolidation. Our 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 (loss) in the stockholders’ equity (deficit) section of the balance sheet. To date, such cumulative translation adjustments have not been significant to our consolidated financial position. Aggregate gross foreign currency transaction gains (losses) recorded in operations for the years ended December 31, 2014, 2013, and 2012 were not significant. The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (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 consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Accounting estimates and assumptions are inherently uncertain. Actual results could differ materially from those estimates and assumptions. On an ongoing basis, we evaluate our estimates, including those related to estimated selling prices of deliverables in collaboration agreements, estimated periods of performance, the net realizable value of inventory, the impairment of investments, the impairment of goodwill and long-lived assets, contingencies, accrued clinical trial expenses, estimated interest expense from our liability related to our sale of future royalties, stock-based compensation, and ongoing litigation, among other estimates. 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. Estimates are assessed each period and updated to reflect current information and any changes in estimates will generally be reflected in the period first identified. *Reclassifications* Certain items previously reported in specific financial statement captions have been reclassified to conform to the current period presentation. Such reclassifications do not materially impact previously reported total revenue, operating loss or net loss or total assets, liabilities or stockholders’ equity (deficit). *Cash, Cash Equivalents, and Investments, and Fair Value of Financial Instruments* We consider all investments in marketable securities with an original maturity of three months or less when purchased to be cash equivalents. Investments in securities with remaining maturities of less than one year, or where our intent is to use the investments to fund current operations or to make them available for current operations, are classified as short-term investments. Investments are designated as available-for-sale and are carried at fair value, with unrealized gains and losses reported in stockholders’ equity (deficit) as accumulated other comprehensive income (loss). The disclosed fair value related to our cash equivalents and investments is based primarily on the reported fair values in our period-end brokerage statements, which are based on market prices from a variety of industry standard data providers and generally represent quoted prices for similar assets in active markets or have been derived from observable market data. We independently validate these fair values using available market quotes and other information. Interest and dividends on securities classified as available-for-sale, as well as amortization of premiums and accretion of discounts to maturity, are included in interest income. Realized gains and losses and declines in value of available-for-sale securities judged to be other-than-temporary, if any, are included in other income (expense). The cost of securities sold is based on the specific identification method. Our cash, cash equivalents, and short-term investments are exposed to credit risk in the event of default by the third parties that hold or issue such assets. Our cash, cash equivalents, and short-term investments are held by financial institutions that management believes are of high credit quality and our investment policy limits investments to fixed income securities denominated and payable in U.S. dollars such as U.S. government obligations, money market instruments and funds, and corporate bonds and places restrictions on maturities and concentrations by type and issuer. *Accounts Receivable and Significant Customer 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 and royalties, as well as time and materials based billings from collaborative research and development agreements. When appropriate, 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 perform a regular review of our customers’ payment histories and associated credit risk. We have not experienced significant credit losses from our accounts receivable. At December 31, 2014, three different customers represented 40%, 31%, and 15%, respectively, of our accounts receivable. At December 31, 2013, three different customers represented 30%, 28%, and 28%, respectively, of our accounts receivable. *Inventory and Significant Supplier Concentrations* Inventory is generally manufactured upon receipt of firm purchase orders from our collaboration partners. Inventory includes direct materials, direct labor, and manufacturing overhead and cost is determined on a first-in, first-out basis. Inventory is valued at the lower of cost or market and defective or excess inventory is written down to net realizable value based on historical experience or projected usage. Inventory related to our research and development activities is expensed when purchased. 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 contract and regulatory requirements. In certain cases, we rely on single sources of supply of one or more critical materials. Consequently, in the event that supplies are delayed or interrupted for any reason, our ability to develop and produce our drug candidates or our ability to meet our supply obligations could be significantly impaired, which could have a material adverse effect on our business, financial condition and results of operations. *Long-Lived Assets* Property, plant and equipment are stated at cost. Major improvements are capitalized, while maintenance and repairs are expensed when incurred. Manufacturing, laboratory and other equipment are depreciated using the straight-line method generally over estimated useful lives of three to seven years. Leasehold improvements and buildings recorded under capital leases are depreciated using the straight-line method over the shorter of the estimated useful life or the remaining term of the lease. Goodwill represents the excess of the price paid for another entity over the fair value of the assets acquired and liabilities assumed in a business combination. We are organized in one reporting unit and evaluate the goodwill for the Company as a whole. Goodwill has an indefinite useful life and is not amortized, but instead tested for impairment annually in the fourth quarter of each year using an October 1 measurement date. We assess the impairment of long-lived assets, primarily property, plant and equipment and goodwill included in other non-current assets, whenever events or changes in business circumstances indicate that the carrying amounts of the assets may not be fully recoverable. When such events occur, we determine whether there has been an impairment in value by comparing the asset’s carrying value with its fair value, as measured by the anticipated undiscounted net cash flows of the asset. In the case of goodwill impairment, market capitalization is generally used as the measure of fair value. If an impairment in value exists, the asset is written down to its estimated fair value. *Revenue Recognition* Our revenue is derived from our arrangements with pharmaceutical and biotechnology collaboration partners and may result from one or more of the following: upfront and license fees, payments for contract research and development, milestone payments, manufacturing and supply payments, and royalties. Our performance obligations under our collaborations may include licensing our intellectual property, manufacturing and supply obligations, and research and development obligations. In order to account for the multiple-element arrangements, the Company identifies the deliverables included within the arrangement and evaluates which deliverables represent separate units of accounting. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver services, a right or license to use an asset, or another performance obligation. Revenue is recognized separately for each identified unit of accounting when the basic revenue recognition criteria are met: there is persuasive evidence that an arrangement exists, delivery has occurred, the price is fixed or determinable, and collection is reasonably assured. At the inception of each new multiple-element arrangement or the material modification of an existing multiple-element arrangement, we allocate all consideration received under multiple-element arrangements to all units of accounting based on the relative selling price method, generally based on our best estimate of selling price (ESP). The objective of ESP is to determine the price at which we would transact a sale if the product or service was sold on a stand-alone basis. We determine ESP for the elements in our collaboration arrangements by considering multiple factors including, but not limited to, technical complexity of the performance obligation and similarity of elements to those performed under previous arrangements. Since we apply significant judgment in arriving at the ESPs, any material change in our estimates would significantly affect the allocation of the total consideration to the different elements of a multiple element arrangement. Product sales Product sales are primarily derived from fixed price and cost-plus manufacturing and supply agreements with our collaboration partners. We have not experienced any significant returns from our customers. Royalty revenues Generally, we are entitled to royalties from our collaboration partners based on the net sales of their approved drugs that are marketed and sold in one or more countries where we hold royalty rights. We recognize royalty revenue when the cash is received or when the royalty amount to be received is estimable and collection is reasonably assured. With respect to the non-cash royalties related to sale of future royalties described at Note 7, revenue is recognized when estimable, otherwise, revenue is recognized during the period in which the related royalty report is received, which generally occurs in the quarter after the applicable product sales are made. License, collaboration and other The amount of upfront fees and other payments received by us in license and collaboration arrangements that are allocated to continuing performance obligations, such as manufacturing and supply obligations, are deferred and generally recognized ratably over our expected performance period under each respective arrangement. We make our best estimate of the period over which we expect to fulfill our performance obligations, which may include technology transfer assistance, research activities, clinical development activities, and manufacturing activities from development through the commercialization of the product. Given the uncertainties of these collaboration arrangements, significant judgment is required to determine the duration of the performance period and this estimate is periodically re-evaluated. 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 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 either on 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, approvals by health authorities, and commercial launches of drugs. Given the challenges inherent in developing and obtaining regulatory approval for drug products and in achieving commercial launches, there was substantial uncertainty whether any such milestones would be achieved at the time of execution of these licensing and collaboration agreements. In addition, we evaluated whether the development milestones meet the remaining criteria to be considered substantive. As a result of our analysis, we consider our remaining development milestones under all of our license and collaboration agreements to be substantive and, accordingly, we expect to recognize as revenue future payments received from such milestones only if and as each milestone is achieved. 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, which is generally upon completion of performance by the respective partner, 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. *Shipping and Handling Costs* We recognize costs related to shipping and handling of product to customers in cost of goods sold. *Research and Development Expense* Research and development costs are expensed as incurred and include salaries, benefits and other operating costs such as outside services, supplies and allocated overhead costs. We perform research and development for our proprietary drug candidates and technology development and for certain third parties under collaboration agreements. For our proprietary drug candidates and our internal technology development programs, we invest our own funds without reimbursement from a third party. We record accruals for the estimated costs of our clinical trial activities performed by third parties. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows to our vendors. Payments under the contracts depend on factors such as the achievement of certain events, successful enrollment of patients, and completion of portions of the clinical trial or similar conditions. We generally accrue costs associated with the start-up and reporting phases of the clinical trials ratably over the estimated duration of the start-up and reporting phases. We generally accrue costs associated with the treatment phase of clinical trials based on the total estimated cost of the treatment phase on a per patient basis and we expense the per patient cost ratably over the estimated patient treatment period based on patient enrollment in the trials. In specific circumstances, such as for certain time-based costs, we recognize clinical trial expenses using a methodology that we consider to be more reflective of the timing of costs incurred. Advance payments for goods or services that will be used or rendered for future research and development activities are capitalized as prepaid expenses and recognized as expense as the related goods are delivered or the related services are performed. We base our estimates on the best information available at the time. However, additional information may become available to us which may allow us to make a more accurate estimate in future periods. In this event, we may be required to record adjustments to research and development expenses in future periods when the actual level of activity becomes more certain. Such increases or decreases in cost are generally considered to be changes in estimates and will be reflected in research and development expenses in the period first identified. During the year ended December 31, 2014, we recorded a reduction related to prior periods of approximately $4.7 million to our research and development expenses primarily related to our Beacon Phase 3 clinical trial for etirinotecan pegol. *Stock-Based Compensation* Stock-based compensation arrangements include stock option grants and restricted stock unit (RSU) awards under our equity incentive plans, as well as shares issued under our Employee Stock Purchase Plan (ESPP), through which employees may purchase our common stock at a discount to the market price. We use the Black-Scholes option pricing model for the respective grant to determine the estimated fair value of the option on the date of grant (grant date fair value) and the estimated fair value of common stock purchased under the ESPP. The Black-Scholes option pricing model requires the input of highly subjective assumptions. These variables include, but are not limited to, our stock price volatility over the term of the awards, and actual and projected employee stock option exercise behaviors. Because our employee stock options have characteristics significantly different from those of traded options, and because changes in the subjective input assumptions can materially affect the fair value estimate, in management’s opinion, the existing models may not provide a reliable single measure of the fair value of our employee stock options or common stock purchased under the ESPP. Management will continue to assess the assumptions and methodologies used to calculate the estimated fair value of stock-based compensation. Circumstances may change and additional data may become available over time, which could result in changes to these assumptions and methodologies, and which could materially impact our fair value determination. We expense the value of the portion of the option or award that is ultimately expected to vest based on the historical forfeiture rate on a straight line basis over the requisite service periods in our Consolidated Statements of Operations. For awards that vest upon the achievement of performance milestones, we estimate the vesting period based on our evaluation of the probability of achievement of each respective milestone and the related estimated date of achievement. Stock-based compensation expense for purchases under the ESPP is recognized over the respective six-month purchase period. Expense amounts are recorded in cost of goods sold, research and development expense, and general and administrative expense based on the function of the applicable employee. Stock-based compensation charges are non-cash charges and as such have no impact on our reported cash flows. *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 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. During 2014, 2013 and 2012, potentially dilutive securities consisted of common shares underlying outstanding stock options and there were weighted average outstanding stock options of 21.9 million, 20.7 million and 18.8 million during the years ended December 31, 2014, 2013 and 2012, respectively. *Income Taxes* We account for income taxes under the liability method. Under this method, 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. When we establish or reduce the valuation allowance related to the deferred tax assets, our provision for income taxes will increase or decrease, respectively, in the period such determination is made. We utilize a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained upon tax authority examination, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon ultimate settlement. *Comprehensive loss* Comprehensive loss is the change in stockholders’ equity (deficit) from transactions and other events and circumstances other than those resulting from investments by stockholders and distributions to stockholders. Our other comprehensive income (loss) is comprised of net loss, gains and losses from the foreign currency translation of the assets and liabilities of our India and UK subsidiaries, and unrealized gains and losses on investments in available-for-sale securities. *Recent Accounting Pronouncements* In May 2014, the Financial Accounting Standards Board (FASB) issued guidance codified in Accounting Standards Codification (ASC) 606, Revenue Recognition — Revenue from Contracts with Customers, which amends the guidance in former ASC 605, Revenue Recognition, and is effective for public companies for fiscal years beginning after December 15, 2016. We are currently evaluating the impact of the provisions of ASC 606. In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (ASU 2014-15). ASU 2014-15 requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. ASU 2014-15 is effective in 2016 with early adoption permitted. We do not believe the impact of adopting ASU 2014-15 on our consolidated financial statements will be significant.

- Definition

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.

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Cash and Investments in Marketable Securities

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Cash and Investments in Marketable Securities

Note 2 — Cash and Investments in Marketable Securities

Cash and investments in marketable securities, including cash equivalents and restricted cash, are as follows (in thousands):


	Estimated Fair Value at
	December 31, 2014		December 31, 2013
Cash and cash equivalents	$	12,365	$	39,067
Short-term investments		225,459		197,959
Restricted cash		25,000		25,000

Total cash and investments in marketable securities	$	262,824	$	262,026

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. As of December 31, 2014 and 2013, all of our investments had contractual maturities of one year or less and were classified as short-term.

Gross unrealized gains and losses were not significant at either December 31, 2014 or 2013. During the years ended December 31, 2014, 2013 and 2012, we sold available-for-sale securities totaling $21.7 million, $2.9 million and $5.4 million respectively, and realized gains and losses were not significant in any of those periods.

Restricted cash of $25.0 million is required to be maintained in a separate account until July 1, 2015 under the terms of our 12% senior secured notes due July 2017. Upon release of this restriction on July 1, 2015, a covenant of the senior secured notes requires that the aggregate balance of our unrestricted cash and cash equivalents at the end of any two consecutive fiscal quarters may not be less than $25.0 million, subject to certain conditions (see Note 5).

Our portfolio of cash and investments in marketable securities includes (in thousands):


	Fair Value Hierarchy Level		Estimated Fair Value at
	Fair Value Hierarchy Level		December 31, 2014		December 31, 2013
Corporate notes and bonds		2	$	182,544	$	138,515
Corporate commercial paper		2		42,915		59,444

Available-for-sale investments				225,459		197,959
Money market funds		1		11,229		26,453
Cash, including restricted cash		N/A		26,136		37,614

Total cash and investments in marketable securities			$	262,824	$	262,026

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.

All of our investments are categorized as Level 1 or Level 2, as explained in the table above. We use a market approach to value our Level 2 investments. During the years ended December 31, 2014, 2013 and 2012, there were no transfers between Level 1 and Level 2 of the fair value hierarchy.

At December 31, 2014 and 2013, we had letter of credit arrangements in favor of a landlord and certain vendors totaling $2.4 million. These letters of credit are secured by investments of similar amounts.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial 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 entity 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 risks 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.

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Inventory

12 Months Ended

Dec. 31, 2014

Inventory Disclosure [Abstract]

Inventory

Note 3 — Inventory

Inventory consists of the following (in thousands):


	December 31,
	2014		2013
Raw materials	$	2,200	$	3,947
Work-in-process		5,187		6,146
Finished goods		5,565		3,359

Inventory	$	12,952	$	13,452

- Definition

The entire disclosure for inventory. This may include, but is not limited to, the basis of stating inventory, the method of determining inventory cost, the major classes of inventory, and the nature of the cost elements included in inventory. If inventory is stated above cost, accrued net losses on firm purchase commitments for inventory and losses resulting from valuing inventory at the lower-of-cost-or-market may also be included. For LIFO inventory, may disclose the amount and basis for determining the excess of replacement or current cost over stated LIFO value and the effects of a LIFO quantities liquidation that impacts net income.

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Property, Plant and Equipment

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Note 4 — Property, Plant and Equipment

Property, plant and equipment consists of the following (in thousands):


	December 31,
	2014			2013
Building and leasehold improvements	$	72,228		$	71,306
Laboratory equipment		26,975			26,621
Manufacturing equipment		25,212			23,699
Furniture, fixtures and other equipment		23,451			23,235

Depreciable property, plant and equipment at cost		147,866			144,861
Less: accumulated depreciation		(93,807	)		(84,148	)

Depreciable property, plant and equipment, net		54,059			60,713
Construction-in-progress		16,309			6,261

Property, plant and equipment, net	$	70,368		$	66,974

Building and leasehold improvements include our manufacturing, research and development and administrative facilities and the related improvements to these facilities. Laboratory and manufacturing equipment include assets that support both our manufacturing and research and development efforts. Construction-in-progress includes assets being built to enhance our manufacturing and research and development efforts, including manufacturing equipment supporting our Amikacin Inhale program at third-party contract manufacturing locations in the U.S. and Germany. Under the terms of our arrangement with these contract manufacturers, during the period the equipment is being constructed, we are obligated to pay for their costs incurred to date. As of December 31, 2014, we have recorded a total of $7.2 million in other current and other long-term liabilities related to our obligation to purchase this equipment, which is recorded in property, plant and equipment. After the assets are placed into service, this liability will be paid over approximately three years.

In July 2012, we consolidated our U.S.-based research activities into our existing San Francisco facility and ceased use of and plan to sell one of our buildings located in Huntsville, Alabama that was dedicated to research activities. The announcement of this consolidation plan in March 2012 triggered the recognition of a $1.7 million impairment charge relating to these assets in the year ended December 31, 2012.

Depreciation expense, including depreciation of assets acquired through capital leases, for the years ended December 31, 2014, 2013, and 2012 was $11.7 million, $13.0 million, and $13.8 million, respectively.

- Definition

The entire disclosure for long-lived, physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, accounting policies and methodology, roll forwards, depreciation, depletion and amortization expense, including composite depreciation, accumulated depreciation, depletion and amortization expense, useful lives and method used, income statement disclosures, assets held for sale and public utility disclosures.

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Senior Secured Notes	12 Months Ended
Senior Secured Notes	Dec. 31, 2014
Debt Disclosure [Abstract]
Senior Secured Notes	Note 5 — Senior Secured Notes On July 11, 2012, we issued $125.0 million in aggregate principal amount of senior secured notes (Senior Notes) with the entire principal amount due on July 15, 2017. The Senior Notes bear interest at 12.0% per annum payable in cash semi-annually in arrears on January 15 and July 15 of each year. The Senior Notes are secured by a first-priority lien on substantially all of our assets. In connection with this transaction, we retired $42.5 million of principal amount of our convertible subordinated notes due September 2012 in exchange for the same principal amount of Senior Notes and received the remaining proceeds in cash, less approximately $4.5 million in transaction costs. We used the proceeds from the issuance of the Senior Notes and our existing cash to repay the remaining $172.4 million in principal amount of our convertible subordinated notes in full at maturity on September 28, 2012. The Senior Notes contain customary covenants, including covenants that limit or restrict our ability to incur liens, incur indebtedness, and make certain restricted payments, but do not contain covenants related to future financial performance. In particular, $25.0 million of the proceeds is required to be maintained in a restricted account until July 1, 2015 and is classified as restricted cash on our Consolidated Balance Sheets. From July 1, 2015 through the quarter ending June 30, 2017, the aggregate balance of our unrestricted cash and cash equivalents at the end of any two consecutive fiscal quarters may not be less than $25.0 million, subject to certain conditions. The Senior Notes are callable by us at any time, subject to certain prepayment premiums and conditions. If we experience certain change of control events, the holders of the Senior Notes will have the right to require us to purchase all or a portion of the Senior Notes at a purchase price in cash equal to 101% of the principal amount thereof, plus accrued and unpaid interest to the date of purchase. In addition, upon certain asset sales, we may be required to offer to use the net proceeds thereof to purchase some of the Senior Notes at 100% of the principal amount thereof, plus accrued and unpaid interest to the date of purchase. As of December 31, 2014, based on a discounted cash flow analysis using Level 3 inputs including financial discount rates, we believe the $125.0 million carrying amount of our 12% Senior Secured Notes due July 2017 is consistent with its fair value.

Leases

12 Months Ended

Dec. 31, 2014

Text Block [Abstract]

Leases

Note 6 — Leases

Capital Leases

We lease office space at 201 Industrial Road in San Carlos, California under a capital lease arrangement. Under the terms of the lease, rent increases up to 3% annually and the lease termination date is October 5, 2016. As of November 29, 2010, we ceased use of this space as a result of the relocation of our San Carlos operations and corporate headquarters to San Francisco, California. As of April 2013, we have subleased all of the San Carlos facility and our future minimum rental receipts under these subleases total $4.8 million as of December 31, 2014.

As of December 31, 2014 and 2013, the gross amount of assets recorded under capital leases was $2.7 million and 2.3 million, respectively, and the recorded value of these assets, net of depreciation, was $1.2 million and $1.0 million, respectively.

Future minimum payments for our capital leases at December 31, 2014 are as follows (in thousands):


Years ending December 31,
2015	$	5,572
2016		4,268
2017		175

Total minimum payments required		10,015
Less: amount representing interest		(1,364	)

Present value of future minimum lease payments		8,651
Less: current portion		(4,512	)

Capital lease obligation, less current portion	$	4,139

Operating Lease

On September 30, 2009, we entered into an operating sublease (Sublease) with Pfizer, Inc. for a 126,285 square foot facility located in San Francisco, California (Mission Bay Facility). Under the terms of the Sublease, we began making non-cancelable lease payments in 2014, after the expiration of our free rent period on August 1, 2014. The Sublease term is 114 months, commencing in August 2010 and terminating on January 31, 2020. Monthly base rent will escalate over the term of the sublease at various intervals. In addition, throughout the term of the Sublease, we are responsible for paying certain costs and expenses specified in the Sublease, including insurance costs and a pro rata share of operating expenses and applicable taxes for the Mission Bay Facility.

Our future minimum lease payments for our operating leases at December 31, 2014 are as follows (in thousands):


Years ending December 31,
2015	$	4,750
2016		4,892
2017		5,037
2018		5,187
2019		5,344
2020		452

Total future minimum lease payments	$	25,662

We recognize rent expense on a straight-line basis over the lease period. For the years ended December 31, 2014, 2013, and 2012, rent expense for all our operating leases, including our Mission Bay Facility, was approximately $3.2 million, $2.9 million, and $2.8 million, respectively.

Liability Related to Sale of Future Royalties

12 Months Ended

Dec. 31, 2014

Text Block [Abstract]

Note 7 — Liability Related to Sale of Future Royalties

On February 24, 2012, we entered into a Purchase and Sale Agreement (the Purchase and Sale Agreement) with RPI Finance Trust (RPI), an affiliate of Royalty Pharma, pursuant to which we sold, and RPI purchased, our right to receive royalty payments (the Royalty Entitlement) arising from the worldwide net sales, from and after January 1, 2012, of (a) CIMZIA^®, under Nektar’s license, manufacturing and supply agreement with UCB Pharma (UCB), and (b) MIRCERA^®, under Nektar’s license, manufacturing and supply agreement with F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. (together referred to as Roche). We received aggregate cash proceeds of $124.0 million for the Royalty Entitlement. As part of this sale, we incurred approximately $4.4 million in transaction costs, which will be amortized to interest expense over the estimated life of the Purchase and Sale Agreement. Although we sold all of our rights to receive royalties from the CIMZIA^® and MIRCERA^® products, as a result of our ongoing manufacturing and supply obligations related to the generation of these royalties, we will continue to account for these royalties as revenue and recorded the $124.0 million in proceeds from this transaction as a liability (Royalty Obligation) that will be amortized using the interest method over the estimated life of the Purchase and Sale Agreement.

The following table shows the activity within the liability account during the year ended December 31, 2014 and for the period from the inception of the royalty transaction on February 24, 2012 (inception) to December 31, 2014 (in thousands):


	Year ended December 31, 2014			Period from inception to December 31, 2014
Liability related to sale of future royalties — beginning balance	$	128,520		$	—
Proceeds from sale of future royalties		—			124,000
Payments from Nektar to RPI		(7,000	)		(10,000	)
Non-cash CIMZIA^® and MIRCERA^® royalty revenue		(21,937	)		(54,783	)
Non-cash interest expense recognized		20,888			61,254

Liability related to sale of future royalties — ending balance	$	120,471		$	120,471

Pursuant to the Purchase and Sale Agreement, in March 2014 and March 2013, we were required to pay RPI $7.0 million and $3.0 million, respectively, as a result of worldwide net sales of MIRCERA^® for the 12 month periods ended on December 31, 2013 and 2012 not reaching certain minimum thresholds. As of December 31, 2014, we do not expect to make any further payments related to the Purchase and Sale Agreement.

As a result of this liability accounting, even though the royalties from UCB and Roche are remitted directly to RPI starting with royalties arising from product sales in the first quarter of 2012, we will continue to recognize revenue for these royalties. During the years ended December 31, 2014, 2013 and 2012, we recognized $21.9 million, $22.1 million and $10.8 million, respectively, in non-cash royalties from net sales of CIMZIA^® and MIRCERA^®.

As royalties are remitted to RPI from Roche and UCB, the balance of the Royalty Obligation will be effectively repaid over the life of the agreement. In order to determine the amortization of the Royalty Obligation, we are required to estimate the total amount of future royalty payments to be received by RPI and payments we are required to make to RPI as noted above over the life of the agreement. The sum of these amounts less the $124.0 million proceeds we received will be recorded as interest expense over the life of the Royalty Obligation. Since inception, our estimate of this total interest expense resulted in an effective annual interest rate of approximately 17%. We periodically assess the estimated royalty payments to RPI from UCB and Roche and to the extent such payments are greater or less than our initial estimates, or the timing of such payments is materially different than our original estimates, we will prospectively adjust the amortization of the Royalty Obligation. There are a number of factors that could materially affect the amount and timing of royalty payments from CIMZIA^® and MIRCERA^®, most of which are not within our control. Such factors include, but are not limited to, changing standards of care, the introduction of competing products, manufacturing or other delays, biosimilar competition, intellectual property matters, adverse events that result in governmental health authority imposed restrictions on the use of the drug products, significant changes in foreign exchange rates as the royalties remitted to RPI are made in U.S. dollars (USD) while significant portions of the underlying sales of CIMZIA^® and MIRCERA^® are made in currencies other than USD, and other events or circumstances that could result in reduced royalty payments from CIMZIA^® and MIRCERA^®, all of which would result in a reduction of non-cash royalty revenues and the non-cash interest expense over the life of the Royalty Obligation. Conversely, if sales of CIMZIA^® and MIRCERA^® are more than expected, the non-cash royalty revenues and the non-cash interest expense recorded by us would be greater over the term of the Royalty Obligation.

In addition, the Purchase and Sale Agreement grants RPI the right to receive certain reports and other information relating to the Royalty Entitlement and contains other representations and warranties, covenants and indemnification obligations that are customary for a transaction of this nature. To our knowledge, we are currently in compliance with these provisions of the Purchase and Sale Agreement, however, if we were to breach our obligations, we could be required to pay damages to RPI that are not limited to the purchase price we received in the sale transaction.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 8 — Commitments and Contingencies *Royalty Expense* We have third party licenses that require us to pay royalties based on our sales of certain products and/or on our recognition of royalty revenue under certain of our collaboration agreements. Royalty expense, which is reflected in cost of goods sold in our Consolidated Statements of Operations, was approximately $3.4 million, $4.1 million, and $2.9 million for the years ended December 31, 2014, 2013, and 2012, respectively. The overall maximum amount of these obligations is based upon sales of the applicable products by our collaboration partners and cannot be reasonably estimated. *Purchase Commitments* In the normal course of business, we enter into various firm purchase commitments related to contract manufacturing, clinical development and certain other items. As of December 31, 2014, these commitments were approximately $16.9 million, all of which are expected to be paid in 2015. *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 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. *Foreign Operations* We operate in a number of foreign countries. As a result, we are subject to numerous local laws and regulations that can result in claims made by foreign government agencies or other third parties that are often difficult to predict even after the application of good faith compliance efforts. *Indemnification Obligations* During the course of our normal operating activities, we have agreed to certain contingent indemnification obligations as further described below. The term of our indemnification obligations is generally perpetual. There is generally no limitation on the potential amount of future payments we could be required to make under these indemnification obligations. To date, we have not incurred significant costs to defend lawsuits or settle claims based on our indemnification obligations. If any of our indemnification obligations is triggered, we may incur substantial liabilities. Because the aggregate amount of any potential indemnification obligation is not a stated amount, the overall maximum amount of any such obligations cannot be reasonably estimated. No liabilities have been recorded for these obligations on our Consolidated Balance Sheets as of December 31, 2014 or 2013. *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 and drug candidates, 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. As part of the sale of our royalty interest in the CIMZIA^® and MIRCERA^® products, we and RPI made representations and warranties and entered into certain covenants and ancillary agreements which are supported by indemnity obligations. Additionally, as part of our pulmonary asset sale to Novartis in 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 is determined that we breached certain of the representations and warranties or covenants and agreements made by us in any such agreements, we could incur substantial indemnification liabilities depending on the timing, nature, and amount of any such claims. *Indemnification of Underwriters and Initial Purchasers of our Securities* In connection with our sale of equity and senior secured debt securities, we have agreed to defend, indemnify and hold harmless our underwriters or initial purchasers, as applicable, as well as certain related parties from and against certain liabilities, including liabilities under the Securities Act of 1933, as amended. *Director and Officer Indemnifications* As permitted under Delaware law, and as set forth in our Certificate of Incorporation and our Bylaws, we indemnify our directors, executive officers, other officers, employees, and other agents for certain events or occurrences that may arise while in such capacity. The maximum potential amount of future payments we could be required to make under this indemnification is unlimited; however, we have insurance policies that may limit our exposure and may enable us to recover a portion of any future amounts paid. Assuming the applicability of coverage, the willingness of the insurer to assume coverage, and subject to certain retention, loss limits and other policy provisions, we believe any obligations under this indemnification would not be material, other than an initial $1,500,000 per incident for merger and acquisition related claims, $1,000,000 per incident for securities related claims and $500,000 per incident for non-securities related claims retention deductible per our insurance policy. However, no assurances can be given that the covering insurers will not attempt to dispute the validity, applicability, or amount of coverage without expensive litigation against these insurers, in which case we may incur substantial liabilities as a result of these indemnification obligations.

- Definition

The entire disclosure for commitments and contingencies.

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Stockholders' Equity

12 Months Ended

Dec. 31, 2014

Equity [Abstract]

Stockholders' Equity

Note 9 — Stockholders’ Equity

Preferred Stock

We have authorized 10,000,000 shares of Preferred Stock with each share having a par value of $0.0001. In 2011, 3,100,000 shares were previously designated Series A Junior Participating Preferred Stock (Series A Preferred Stock) in connection with our Share Purchase Rights Plan (Rights Plan) that expired on June 1, 2011. On March 30, 2012, we filed a certificate of elimination of the Series A Preferred Stock. As of December 31, 2014 and 2013, no preferred shares are designated, issued or outstanding.

Common Stock

On January 28, 2014, we completed the issuance and sale of 9,775,000 shares of our common stock in a public offering with total proceeds of approximately $117.2 million after deducting the underwriting commissions and discounts of approximately $7.5 million. In addition, we incurred approximately $0.6 million in legal and accounting fees, filing fees, and other costs in connection with this offering.

Equity Compensation Plans

At December 31, 2014, we had 24,806,565 reserved shares of common stock, all of which are reserved for issuance under our equity compensation plans as summarized in the following table (share number in thousands):


Plan Category	Number of Securities to be Issued Upon Exercise of Outstanding Options (a)		Weighted-Average Exercise Price of Outstanding Options (b)		Number of Securities Remaining Available for Issuance Under Equity Compensation Plans (Excluding Securities Reflected in Column(a)) (c)
Equity compensation plans approved by security holders(1)		18,601	$	10.68		2,812
Equity compensation plans not approved by security holders		3,394	$	9.52		—

Total		21,995	$	10.50		2,812

(1)	Includes shares of common stock available for future issuance under our ESPP as of December 31, 2014.

2012 Performance Incentive Plan

Our 2012 Performance Incentive Plan (2012 Plan) was adopted by the Board of Directors on April 4, 2012 and was approved by our stockholders on June 28, 2012. On the date of approval, any shares of our common stock that were available for issuance under all other previously existing stock plans (the 2008 Equity Incentive Plan, the 2000 Equity Incentive Plan, and the 2000 Non-Officer Equity Incentive Plan) became available for issuance under the 2012 Plan. In addition, 5,300,000 new shares were made available for award grants under the 2012 Plan. No new awards were granted under any of the previous stock plans after June 28, 2012. Any shares of common stock subject to outstanding awards under the previous stock plans that expire, are cancelled, or otherwise terminate at any time after December 31, 2011 are also available for award grant purposes under the 2012 Plan.

The purpose of the 2012 Plan and our other incentive plans is to attract, motivate, retain, and reward directors, officers, employees, and other eligible persons through the grant of awards and incentives for high levels of individual performance and increasing the value of our business, as well as to further align the interests of award recipients and our stockholders. The 2012 Plan authorizes stock options, stock appreciation rights, restricted stock, performance stock, stock units, stock bonuses, dividend equivalents, other similar rights to purchase or acquire shares, and other forms of awards granted or denominated in our common stock or units of the company’s common stock, as well as cash bonus awards. Directors, officers, or employees, and certain consultants and advisors may receive awards under the 2012 Plan. Pursuant to the 2012 Plan, we granted or issued incentive stock options to officers and non-qualified stock options to employees, officers, and non-employee directors. In 2013 and 2014, the requisite service period for stock options granted to our employees under the 2012 Plan as well as all other previously existing stock plans was generally four years; the requisite service period for stock options granted to our directors was generally one year.

The maximum number of shares of our common stock that may be issued or transferred pursuant to awards under the 2012 Plan is 10,347,140 shares, plus any shares subject to outstanding awards under the previous stock plans that expire, are cancelled, or otherwise terminate for any reason. Generally, shares that are subject to or underlie awards which expire or for any reason are cancelled or terminated, are forfeited, fail to vest, or for any other reason (except for shares exchanged by a participant or withheld to pay the exercise price of an award granted and related tax withholding obligations) are not paid or delivered under the 2012 Plan will again be available for subsequent awards under the 2012 Plan. Shares issued in respect of any award, other than a stock option or stock appreciation right, granted under the 2012 Plan will be counted against the plan’s share limit as 1.5 shares for every one share actually issued in connection with the award. We did not grant any RSU awards during the years ended December 31, 2014, 2013 or 2012 and no RSUs are outstanding at December 31, 2014.

The 2012 Plan will terminate on April 3, 2022, unless earlier terminated by the Board of Directors. The maximum term of a stock option or stock appreciation right under the 2012 Plan is eight years from the date of grant. The per share exercise price of an option generally may not be less than the fair market value of a share of the company’s common stock on the Nasdaq Global Select Market on the date of grant.

Other Equity Incentive Plans

In addition to the 2012 Plan, we have other equity incentive plans under which options granted remain outstanding but no new options may be granted either as a result of the approval of the 2012 Plan or plan expiration. These plans include: (i) the 2008 Equity Incentive Plan (2008 Plan) which was adopted by the Board of Directors on March 20, 2008 and approved by our stockholders on June 6, 2008; (ii) the 2000 Equity Incentive Plan (2000 Plan) which was adopted by the Board of Directors on April 19, 2000 by amending and restating our 1994 Equity Incentive Plan, and which expired on February 9, 2010; and (iii) the 1998 Non-Officer Equity Incentive Plan which was adopted by our Board of Directors on August 18, 1998, and which was amended and restated in its entirety and renamed the 2000 Non-Officer Equity Incentive Plan on June 6, 2000 (2000 Non-Officer Plan).

Pursuant to the 2008 Plan and the 2000 Plan, we previously granted or issued incentive stock options to employees and officers and non-qualified stock options, rights to acquire restricted stock, restricted stock units, and stock bonuses to employees, officers, non-employee directors, and consultants. Pursuant to the 2000 Non-Officer Plan, we previously granted or issued non-qualified stock options, rights to acquire restricted stock and stock bonuses to employees and consultants who are neither officers nor directors of Nektar. The maximum term of a stock option under all of these plans is eight years.

Employee Stock Purchase Plan

In February 1994, our Board of Directors adopted the Employee Stock Purchase Plan (ESPP) pursuant to section 423(b) of the Internal Revenue Code of 1986. Under the ESPP, 2,500,000 shares of our common stock have been authorized for issuance. The terms of the ESPP provide eligible employees with the opportunity to acquire an ownership interest in Nektar through participation in a program of periodic payroll deductions for the purchase of our common stock. Employees may elect to enroll or re-enroll in the ESPP on a semi-annual basis. Stock is purchased at 85% of the lower of the closing price on the first day of the enrollment period or the last day of the enrollment period.

401(k) Retirement Plan

We sponsor a 401(k) retirement plan whereby eligible employees may elect to contribute up to the lesser of 60% of their annual compensation or the statutorily prescribed annual limit allowable under Internal Revenue Service regulations. The 401(k) plan permits us to make matching contributions on behalf of all participants, up to a maximum of $3,000 per participant. For the years ended December 31, 2014, 2013, and 2012, we recognized $0.9 million, $1.0 million, and $0.9 million, respectively, of compensation expense in connection with our 401(k) retirement plan.

Change in Control Severance Plan

On December 6, 2006, our Board of Directors approved a Change of Control Severance Benefit Plan (CIC Plan). This CIC Plan has subsequently been amended a number of times by our Board of Directors with the most recent amendment occurring on April 5, 2011. The CIC Plan is designed to make certain benefits available to our eligible employees in the event of a change of control of Nektar and, following such change of control, an employee’s employment with us or a successor company is terminated in certain specified circumstances. We adopted the CIC Plan to support the continuity of the business in the context of a change of control transaction. The CIC Plan was not adopted in contemplation of any specific change of control transaction.

Under the CIC Plan, in the event of a change of control of Nektar and a subsequent termination of employment initiated by us or a successor company other than for Cause (as defined in the CIC Plan) or initiated by the employee for a Good Reason Resignation (as defined in the CIC Plan) in each case within twelve months following a change of control transaction, (i) the Chief Executive Officer would be entitled to receive cash severance pay equal to 24 months base salary plus annual target incentive pay, the extension of employee benefits over this severance period and the full acceleration of unvested outstanding equity awards, and (ii) our Senior Vice Presidents and Vice Presidents (including Principal Fellows) would each be entitled to receive cash severance pay equal to twelve months base salary plus annual target incentive pay, the extension of employee benefits over this severance period and the full acceleration of unvested outstanding equity awards. In the event of a change of control of Nektar and a subsequent termination of employment initiated by the Company or a successor company other than for Cause within twelve months following a change of control transaction, all other employees would each be entitled to receive cash severance pay equal to 6 months base salary plus a pro-rata portion of annual target incentive pay, the extension of employee benefits over this severance period and the full acceleration of each such employee’s unvested outstanding equity awards. Under the CIC Plan, as amended, non-employee directors would also be entitled to full acceleration of vesting of all outstanding stock awards in the event of a change of control transaction.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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+ Details

License and Collaboration Agreements

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

License and Collaboration Agreements

Note 10 — License and Collaboration Agreements

We have entered into various collaboration agreements including license agreements and collaborative research, development and commercialization agreements with various pharmaceutical and biotechnology companies. Under these collaboration arrangements, we are entitled to receive license fees, upfront payments, milestone payments, royalties, sales milestones, and payments for the manufacture and supply of our proprietary PEGylation materials and/or reimbursement for research and development activities. All of our collaboration agreements are generally cancelable by our partners without significant financial penalty. Our costs of performing these services are generally included in research and development expense, except that costs for product sales to our collaboration partners are included in cost of goods sold.

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


		Year Ended December 31,
Partner	Agreement	2014		2013		2012
AstraZeneca AB	MOVANTIK^TM (NKTR-118) and MOVANTIK^TM fixed-dose combination program (NKTR-119)	$	105,001	$	25,016	$	59
Roche	PEGASYS^® and MIRCERA^®		12,845		18,382		7,146
Baxter Healthcare	BAX 855 (Hemophilia)		10,258		1,702		6,238
Amgen, Inc.	Neulasta^®		5,000		5,035		5,000
Bayer Healthcare LLC	BAY41-6551 (Amikacin Inhale)		4,717		15,293		2,971
Affymax, Inc.	OMONTYS^®		—		7,149		2,829
Other			15,468		8,295		5,884

License, collaboration and other revenue		$	153,289	$	80,872	$	30,127

As of December 31, 2014, our collaboration agreements with partners included potential future payments for development milestones totaling approximately $130.3 million, including amounts from our agreements with Baxter and Bayer described below. In addition, we are entitled to receive the contingent payments described below related to the MOVANTIK^TM (previously referred to as naloxegol and NKTR-118) and MOVANTIK^TM fixed-dose combination (previously referred to as NKTR-119) drug development programs, respectively, based on development and regulatory events to be pursued and completed solely by AstraZeneca.

AstraZeneca AB: MOVANTIK^TM (naloxegol oxalate), previously referred to as naloxegol and NKTR-118, and MOVANTIK^TM fixed-dose combination program, previously referred to as NKTR-119

In September 2009, we entered into a license agreement with AstraZeneca AB (AstraZeneca), as amended by AstraZeneca and us in August 2013, under which we granted AstraZeneca a worldwide, exclusive, perpetual, royalty-bearing, and sublicensable license under our patents and other intellectual property to develop, market, and sell MOVANTIK^TM and MOVANTIK^TM fixed-dose combination program. AstraZeneca is responsible for all costs associated with research, development and commercialization and is responsible for all drug development and commercialization decisions for MOVANTIK^TM and the MOVANTIK^TM fixed-dose combination program. AstraZeneca paid us an upfront payment of $125.0 million, which we received in the fourth quarter of 2009 and which was fully recognized as of December 31, 2010. As of December 31, 2014, we are entitled to receive up to an additional $140.0 million and $75.0 million of contingent payments related to MOVANTIK^TM and the MOVANTIK^TM fixed-dose combination program, respectively, based on development events to be pursued and completed solely by AstraZeneca, as described below.

On September 16, 2014, the United States Food and Drug Administration (FDA) approved MOVANTIK^TM for the treatment of opioid-induced constipation (OIC) in adult patients with chronic, non-cancer pain. On December 9, 2014, AstraZeneca announced that MOVENTIG^® (the naloxegol brand name in the European Union) has been granted Marketing Authorisation by the European Commission (EC) for the treatment of opioid-induced constipation (OIC) in adult patients who have had an inadequate response to laxative(s). As a result of the FDA’s approval, on September 16, 2014, we were entitled to a $35.0 million non-refundable payment from AstraZeneca, which was fully recognized as revenue in September 2014 and was received in October 2014. In addition, the FDA’s approval of MOVANTIK^TM extinguished our contingent obligation to repay the $70.0 million payment made to us by AstraZeneca in November 2013 after the MOVANTIK^TM New Drug Application was accepted for review by the FDA. As a result, in September 2014, we fully recognized this $70.0 million payment, which was previously recorded in the line item “Liability related to receipt of refundable milestone payment” on our Consolidated Balance Sheet at December 31, 2013.

As part of its approval of MOVANTIK^TM, the FDA required AstraZeneca to perform a post-marketing, observational epidemiological study comparing MOVANTIK^TM to other treatments of OIC in patients with chronic, non-cancer pain. As a result, the royalty rate payable to us from net sales of MOVANTIK^TM in the U.S. by AstraZeneca will be reduced by up to two percentage points to fund 33% of the external costs incurred by AstraZeneca to fund such post approval study subject to a $35.0 million aggregate cap. Any costs incurred by AstraZeneca can only be recovered by the reduction of the royalty paid to us. In no case can amounts be recovered by the reduction of a contingent payment due from AstraZeneca to us or through a payment from us to AstraZeneca.

We will be entitled to up to an additional $140.0 million of contingent payments upon the first commercial sale of MOVANTIK^TM, $100.0 million of which will be payable upon the first commercial sale in the U.S. and $40.0 million of which will be payable upon the first commercial sale in one major European Union country. We are also entitled to receive up to $75.0 million of commercial launch contingent payments related to the MOVANTIK^TM fixed-dose combination program, based on development events to be pursued and completed solely by AstraZeneca. In addition, we are entitled to royalties and sales milestone payments based on annual worldwide net sales of MOVANTIK^TM and MOVANTIK^TM fixed-dose combination products.

Roche: PEGASYS^® and MIRCERA^®

In February 1997, we entered into a license, manufacturing and supply agreement with Roche, under which we granted Roche a worldwide, exclusive license to certain intellectual property related to our proprietary PEGylation materials used in the manufacture and commercialization 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 perform additional manufacturing, if any, only on an as-requested basis. In connection with Roche’s exercise of the license extension option in December 2009, we received a payment of $31.0 million. As of December 31, 2014, we have deferred revenue of approximately $5.1 million related to this agreement, which we expect to recognize through December 2015, the period through which we are required to provide back-up manufacturing and supply services related to PEGASYS^®.

In February 2012, we entered into a toll-manufacturing agreement with Roche under which we will manufacture the proprietary PEGylation material used by Roche to produce MIRCERA^®. Roche entered into the toll-manufacturing agreement with the objective of establishing us as a secondary back-up supply source on a non-exclusive basis. Under the terms of our toll-manufacturing agreement, Roche paid us an upfront payment of $5.0 million and an additional $22.0 million in performance-based milestone payments upon our achievement of certain manufacturing readiness, validation and production milestones, including the delivery of specified quantities of PEGylation materials, all of which were completed as of January 2013. Roche will also pay us additional consideration for any future orders of the PEGylation materials for MIRCERA^® beyond the initial quantities manufactured through January 2013. Roche has the right to terminate the toll-manufacturing agreement due to an uncured material default by us.

We analyzed the milestone payments under the agreement and determined that they did not meet the criteria for revenue recognition under the milestone method as a result of our continuing manufacturing obligations. We have identified our back-up manufacturing obligation through December 2016 and the delivery of PEGylation materials specified in the agreement in 2012 and early 2013 as the units of accounting in the arrangement. We made our best estimate of the selling prices for these deliverables and have allocated the total $27.0 million consideration to these items based on the relative selling price method. As of December 31, 2014, we have deferred revenue of approximately $10.7 million, which we expect to recognize through December 2016, the estimated end of our obligations under this agreement.

In August 2013, we agreed to deliver additional quantities of PEGylation materials used by Roche to produce PEGASYS^® and MIRCERA^®, all of which were delivered in the last quarter of 2013, for total consideration of $18.6 million. We determined that these incremental activities should be considered a material modification of the existing PEGASYS^® and MIRCERA^® -related arrangements described above. As a result, we allocated the $18.6 million consideration to each of these arrangements and determined the amounts to be recognized or deferred based on the estimated selling prices of the undelivered obligations. As of December 31, 2014, we have deferred revenue of approximately $4.6 million related to these activities, which we expect to recognize through December 2016, the estimated end of our obligations under the modified arrangements.

Baxter Healthcare: BAX 855/Hemophilia

In September 2005, we entered into an exclusive research, development, license and manufacturing and supply agreement with Baxter Healthcare SA and Baxter Healthcare Corporation (together referred to as Baxter) to develop products designed to improve therapies for Hemophilia A patients using our PEGylation technology. Under the terms of the agreement, we are entitled to research and development funding and are responsible for supplying Baxter with its requirements for our proprietary materials. Baxter is responsible for all clinical development, regulatory, and commercialization expenses. The agreement is terminable by the parties under customary conditions.

Under the terms of this agreement, as of December 31, 2014, we are entitled to up to $20.0 million of development milestones related to Hemophilia A upon achievement of certain development objectives, as well as sales milestones upon achievement of annual sales targets and royalties based on annual worldwide net sales of products resulting from this agreement. This Hemophilia A program includes BAX 855. In August 2014, Baxter announced positive top-line results from its Phase 3 pivotal clinical trial of BAX 855 which met the primary endpoint for the control and prevention of bleeding, routine prophylaxis and perioperative management for patients who were 12 years or older. As a result of this Phase 3 clinical trial meeting its primary endpoint, we achieved development milestones totaling $8.0 million. Given our significant efforts in the development of this product, we consider these milestones to be substantive and we recognized the milestones in their entirety in the year ended December 31, 2014. As of December 31, 2014, we do not have significant deferred revenue related to this agreement.

Amgen, Inc.: Neulasta^®

In October 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 (the Facility). This supply arrangement is on a non-exclusive basis (other than the use of the Manufacturing Suite and certain equipment) whereby we are 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. Our research facility in Huntsville, Alabama that we propose to sell is a different building and location from that of the Facility described here.

As of December 31, 2014, we have deferred revenue of approximately $29.2 million related to this agreement, which we expect to recognize through October 2020, the estimated end of our obligations under this agreement.

Bayer Healthcare LLC: BAY41-6551 (Amikacin Inhale)

In August 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. In the years prior to 2014, we received an upfront payment of $40.0 million in 2007 and milestone payments of $30.0 million, including a $10.0 million development milestone which was achieved in 2013 as a result of the start of the Phase 3 clinical trial by Bayer in the treatment of intubated and mechanically ventilated patients with Gram-negative pneumonia in April 2013. In addition, in June 2013, we paid $10.0 million to Bayer for the reimbursement of its costs of the Phase 3 clinical trial.

In addition, we are entitled to receive a total of up to $50.0 million for development milestones upon achievement of certain development objectives, as well as sales milestones upon achievement of annual sales targets and royalties based on annual worldwide net sales of Amikacin Inhale. As of December 31, 2014, we have deferred revenue of approximately $20.8 million related to this agreement, which we expect to recognize through February 2028, the estimated end of our obligations under this agreement.

Ophthotech Corporation: Fovista^®

We are a party to an agreement with Ophthotech Corporation (Ophthotech), dated September 30, 2006, under which Ophthotech received a worldwide, exclusive license to certain of our proprietary PEGylation technology to develop, manufacture and sell Fovista^®. Under the terms of our agreement, we are the exclusive supplier of all of Ophthotech’s clinical and commercial requirements for our proprietary PEGylation reagent used in Fovista^®. On May 19, 2014, Ophthotech entered into a Licensing and Commercialization Agreement with Novartis Pharma AG for Fovista^®. Under our agreement with Ophthotech, we received a $19.75 million payment in connection with this licensing agreement in June 2014. As of December 31, 2014, we have deferred revenue of approximately $18.9 million related to this agreement, which we expect to recognize through March 2028, the estimated end of our obligations under our agreement with Ophthotech.

In addition, we are entitled to up to $9.5 million in additional payments based upon Ophthotech’s potential achievement of certain regulatory and sales milestones. We are also entitled to royalties on net sales of Fovista^® that vary based on sales levels.

Affymax, Inc.: OMONTYS^®

In April 2004, we entered into a license, manufacturing and supply agreement with Affymax, Inc. (Affymax) under which we provided Affymax with a worldwide, non-exclusive license under certain of our proprietary PEGylation technology to develop, manufacture and commercialize OMONTYS^® (peginesatide). On February 23, 2013, Affymax and Takeda Pharmaceutical Company Limited announced a voluntary recall of all lots of OMONTYS^® drug product as a result of new post-marketing reports regarding serious hypersensitivity reactions, including anaphylaxis, which can be life-threatening or fatal. In July 2013, Affymax terminated the license, manufacturing and supply agreement with Nektar.

We have received milestone and related payments under our agreement with Affymax and, as a result of the termination of our agreement with Affymax and our related performance obligations, we recognized the remaining $6.7 million of deferred revenue from this agreement in the year ended December 31, 2013.

Other

During the year ended December 31, 2014, two of our collaboration partners achieved the successful transfer of our commercial manufacturing process in connection with the PEGylation materials used in their products. In connection with our assistance with these manufacturing technology transfers, we received a total of $9.0 million of milestone payments. We concluded that these payments are substantive milestones and recognized them in their entirety in the year ended December 31, 2014.

In addition, as of December 31, 2014, we have a number of collaboration agreements, including our collaboration partner UCB, under which we are entitled to up to a total of $53.8 million of development milestones upon achievement of certain development objectives, as well as sales milestones upon achievement of annual sales targets and royalties based on net sales of commercialized products, if any. However, given the current phase of development of the potential products under these collaboration agreements, we cannot estimate the probability or timing of achieving these milestones.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

Note 11 — Stock-Based Compensation

We issue stock-based awards from our equity incentive plans, which are more fully described in Note 9. Stock-based compensation expense was recognized as follows (in thousands):


	Year Ended December 31,
	2014		2013		2012
Cost of goods sold	$	1,161	$	1,297	$	1,496
Research and development		7,528		7,910		7,082
General and administrative		8,328		8,501		7,621

Total stock-based compensation	$	17,017	$	17,708	$	16,199

As of December 31, 2014, total unrecognized compensation costs of $51.9 million related to unvested stock-based compensation arrangements are expected to be recognized as expense over a weighted-average period of 2.1 years.

Black-Scholes Assumptions

The following tables list the Black-Scholes option-pricing model assumptions used to calculate the fair value of employee and director stock options.


	Year Ended December 31, 2014			Year Ended December 31, 2013			Year Ended December 31, 2012
Average risk-free interest rate		1.6	%		0.9	%		0.9	%
Dividend yield		0.0	%		0.0	%		0.0	%
Average volatility factor		51.6	%		61.2	%		62.2	%
Average weighted average expected life		5.2 years			5.2 years			5.0 years

The average risk-free interest rate is based on the U.S. treasury yield curve in effect at the time of grant for periods commensurate with the expected life of the stock-based award. We have never paid dividends, nor do we expect to pay dividends in the foreseeable future; therefore, we used a dividend yield of 0.0%. Our estimate of expected volatility is based on the daily historical trading data of our common stock at the time of grant over a historical period commensurate with the expected life of the stock-based award.

For the years ended December 31, 2014, 2013, and 2012, we estimated the weighted-average expected life based on the contractual and vesting terms of the stock options, as well as historic cancellation and exercise data.

Stock-based compensation resulting from our ESPP was not material in the years ended December 31, 2014, 2013, and 2012.

Summary of Stock Option Activity

The table below presents a summary of stock option activity under our equity incentive plans (in thousands, except for price per share and contractual life information):


	Number of Shares			Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Life (in Years)		Aggregate Intrinsic Value⁽¹⁾
Outstanding at December 31, 2013		20,655		$	9.06
Options granted		7,713			13.96
Options exercised		(4,852	)		9.43
Options forfeited & canceled		(1,521	)		11.89

Outstanding at December 31, 2014		21,995		$	10.50		4.96	$	112,549

Vested and expected to vest at December 31, 2014		21,338		$	10.41		4.89	$	111,071
Exercisable at December 31, 2014		13,007		$	8.90		3.47	$	85,839

(1)	Aggregate intrinsic value represents the difference between the exercise price of the option and the closing market price of our common stock on December 31, 2014.

The weighted-average grant-date fair value per share of options granted during the years ended December 31, 2014, 2013, and 2012 was $6.50, $4.95, and $3.92, respectively. The total intrinsic value of options exercised during the years ended December 31, 2014, 2013, and 2012 was $25.9 million, $4.5 million, and $1.9 million, respectively. The estimated fair value of options vested during the years ended December 31, 2014, 2013, and 2012 was $15.2 million, $14.1 million, and $15.7 million, respectively.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References+ Details

Income Taxes

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Income Taxes

Note 12 — Income Taxes

Loss before (benefit) provision for income taxes includes the following components (in thousands):


	Year Ended December 31,
	2014			2013			2012
Domestic	$	(56,414	)	$	(161,068	)	$	(174,258	)
Foreign		1,986			1,300			2,809

Loss before (benefit) provision for income taxes	$	(54,428	)	$	(159,768	)	$	(171,449	)

Provision for Income Taxes

The (benefit) provision for income taxes consists of the following (in thousands):


	Year Ended December 31,
	2014			2013			2012
Current:
Federal	$	—		$	—		$	(137	)
State		1			1			1
Foreign		(482	)		1,838			1,029

Total Current		(481	)		1,839			893

Deferred:
Federal		—			422			(422	)
State		—			49			(49	)
Foreign		(31	)		(65	)		(16	)

Total Deferred		(31	)		406			(487	)

(Benefit) provision for income taxes	$	(512	)	$	2,245		$	406

The foreign benefit provision in the year ended December 31, 2014 is due to the reduction in taxes related to a favorable determination received from India proceedings.

Income tax provision related to continuing operations differs from the amount computed by applying the statutory income tax rate of 35% to pretax loss as follows (in thousands):


	Year Ended December 31,
	2014			2013			2012
U.S. federal provision (benefit)
At statutory rate	$	(19,050	)	$	(55,919	)	$	(60,007	)
State taxes		1			50			(48	)
Change in valuation allowance		11,831			55,042			47,349
Non-cash interest expense on liability related to sale of future royalties		7,311			7,808			6,320
Stock-based compensation		2,832			271			236
Foreign tax inclusion		—			—			6,510
Foreign tax differential		(17	)		(20	)		(227	)
Research credits		(2,933	)		(6,273	)		(591	)
Other		(487	)		1,286			864

(Benefit) provision for income taxes	$	(512	)	$	2,245		$	406

Deferred Tax Assets and Liabilities

Deferred income taxes reflect the net tax effects of loss and credit carryforwards and temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of our deferred tax assets for federal and state income taxes are as follows (in thousands):


	December 31,
	2014			2013
Deferred tax assets:
Net operating loss carryforwards	$	423,776		$	391,385
Research and other credits		66,666			61,707
Deferred revenue		29,758			35,588
Stock-based compensation		21,948			25,962
Sale of future royalties		20,153			28,057
Capitalized research expenses		14,795			17,687
Reserves and accruals		8,288			14,685
Property, plant and equipment		8,264			8,580
Other		2,218			2,539

Deferred tax assets before valuation allowance		595,866			586,190
Valuation allowance for deferred tax assets		(595,690	)		(586,040	)

Total deferred tax assets		176			150

Total deferred tax liabilities		—			—

Net deferred tax assets	$	176		$	150

Realization of our deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Because of our lack of U.S. earnings history, the net U.S. deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $9.7 million and $51.8 million during the years ended December 31, 2014 and 2013, respectively. The valuation allowance includes approximately $35.6 million of income tax benefit at both December 31, 2014 and December 31, 2013 related to stock-based compensation and exercises prior to the implementation of the accounting guidance for stock-based compensation that will be credited to additional paid in capital when realized.

Undistributed earnings of our foreign subsidiary in India are considered to be permanently reinvested and accordingly, no deferred U.S. income taxes have been provided thereon. Upon distribution of those earnings in the form of dividends or otherwise, we would be subject to U.S. income tax. As of December 31, 2014, U.S. income taxes have not been provided on a cumulative total of $3.9 million of such earnings. Any incremental tax liability would be insignificant due to foreign tax credits that would be realized upon distribution.

Net Operating Loss and Tax Credit Carryforwards

As of December 31, 2014, we had a net operating loss carryforward for federal income tax purposes of approximately $1,131.8 million, portions of which will begin to expire in 2018. As of December 31, 2014, we had a total state net operating loss carryforward of approximately $709.2 million, of which approximately $124.6 million does not meet the more likely than not standard and has not been included in our deferred tax assets. Our state operating loss carryforwards will begin to expire in 2015. Utilization of some of the federal and state net operating loss and credit carryforwards are subject to annual limitations due to the “change in ownership” provisions of the Internal Revenue Code of 1986 and similar state provisions.

We have federal research credits of approximately $40.0 million, which will begin to expire in 2019 and state research credits of approximately $22.6 million which have no expiration date. We have federal orphan drug credits of $17.7 million which will begin to expire in 2026. These tax credits are subject to the same limitations discussed above.

Unrecognized tax benefits

We have incurred net operating losses since inception. Our policy is to include interest and penalties related to unrecognized tax benefits, if any, within the provision for income taxes in the consolidated statements of operations. If we are eventually able to recognize our uncertain positions, our effective tax rate may be reduced. We currently have a full valuation allowance against our U.S. net deferred tax asset which would impact the timing of the effective tax rate benefit should any of these uncertain tax positions be favorably settled in the future. Any adjustments to our uncertain tax positions would result in an adjustment of our net operating loss or tax credit carry forwards rather than resulting in a cash outlay.

We file income tax returns in the U.S., California, Alabama, and India. Because of net operating losses and research credit carryovers, substantially all of our domestic tax years remain open and subject to examination. We are currently under examination in India for the fiscal years ending 2009 through 2014.

We have the following activity relating to unrecognized tax benefits (in thousands):


	December 31,
	2014			2013		2012
Beginning balance	$	16,363		$	14,067	$	13,576
Tax positions related to current year
Additions:
Federal		502			477		289
State		6,141			381		302
Reductions		—			—		—
Tax positions related to prior year
Additions:
Federal		—			636		37
State		5,258			—		—
Foreign		—			802		—
Reductions — foreign		(742	)		—		—
Settlements		—			—		—
Lapses in statute of limitations		—			—		(137	)

Ending balance	$	27,522		$	16,363	$	14,067

Although it is reasonably possible that certain unrecognized tax benefits may increase or decrease within the next twelve months, we do not anticipate any significant changes to unrecognized tax benefits over the next twelve months. During the years ended December 31, 2014, 2013 and 2012, no significant interest or penalties were recognized relating to unrecognized tax benefits.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References+ Details

Segment Reporting

12 Months Ended

Dec. 31, 2014

Segment Reporting [Abstract]

Segment Reporting

Note 13 — Segment Reporting

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. Within our one business segment we have two components, PEGylation technology and pulmonary technology.

Our revenue is derived primarily from clients in the pharmaceutical and biotechnology industries. AstraZeneca, UCB and Roche represented 52%, 16%, and 11% of our revenue, respectively, for the year ended December 31, 2014. Revenue from Roche, UCB, AstraZeneca and Bayer represented 28%, 21%, 17% and 10% of our revenue, respectively, for the year ended December 31, 2013. Revenue from UCB, Roche and Affymax represented 30%, 23% and 11% of our revenue, respectively, for the year ended December 31, 2012.

Revenue by geographic area is based on the locations of our partners. The following table sets forth revenue by geographic area (in thousands):


	Year Ended December 31,
	2014		2013		2012
United States	$	32,514	$	42,535	$	34,591
Europe		168,193		106,386		46,600

Total revenue	$	200,707	$	148,921	$	81,191

At December 31, 2014, $63.3 million, or approximately 90%, of the net book value of our property and equipment was located in the United States and $7.1 million, or approximately 10%, was located in India. At December 31, 2013, $57.3 million, or approximately 88%, of the net book value of our property and equipment was located in the United States and $7.7 million, or approximately 12%, was located in India.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Selected Quarterly Financial Data

12 Months Ended

Dec. 31, 2014

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data

Note 14 — Selected Quarterly Financial Data (Unaudited)

The following table sets forth certain unaudited quarterly financial data. In our opinion, the unaudited information set forth below has been prepared on the same basis as the audited information and includes all adjustments necessary to present fairly the information set forth herein. We have experienced fluctuations in our quarterly results and expect these fluctuations to continue in the future. Due to these and other factors, we believe that quarter-to-quarter comparisons of our operating results will not be meaningful, and you should not rely on our results for any one quarter as an indication of our future performance. Certain items previously reported in specific financial statement captions have been reclassified to conform to the current period presentation. Such reclassifications have not materially impacted previously reported total revenues, operating loss or net loss. All data is in thousands except per share information.


	Fiscal Year 2014											Fiscal Year 2013
	Q1			Q2			Q3		Q4			Q1			Q2			Q3			Q4
Product sales	$	5,795		$	5,802		$	6,096	$	7,460		$	11,810		$	10,324		$	14,672		$	8,040
Total revenue	$	19,771		$	28,513		$	132,871	$	19,551		$	23,004		$	33,862		$	60,909		$	31,146
Cost of goods sold	$	7,907		$	5,108		$	9,220	$	6,298		$	11,661		$	5,011		$	12,877		$	8,960
Research and development expenses	$	38,338		$	36,702		$	34,200	$	38,494		$	45,618		$	52,230		$	43,914		$	48,248
Operating income (loss)	$	(36,402	)	$	(22,916	)	$	80,321	$	(37,488	)	$	(45,106	)	$	(32,605	)	$	(6,525	)	$	(35,894	)
Net income (loss)	$	(46,201	)	$	(32,637	)	$	70,605	$	(45,683	)	$	(55,063	)	$	(42,748	)	$	(16,543	)	$	(47,659	)
Net income (loss) per share(1)
Basic	$	(0.37	)	$	(0.26	)	$	0.55	$	(0.35	)	$	(0.48	)	$	(0.37	)	$	(0.14	)	$	(0.41	)
Diluted	$	(0.37	)	$	(0.26	)	$	0.53	$	(0.35	)	$	(0.48	)	$	(0.37	)	$	(0.14	)	$	(0.41	)

(1)	Quarterly loss per share amounts may not total to the year-to-date loss per share due to rounding.

- Definition

The entire disclosure for the quarterly financial data in the annual financial statements. The disclosure may include a tabular presentation of financial information for each fiscal quarter for the current and previous year, including revenues, gross profit, income or loss before extraordinary items and earnings per share data. It also includes an indication if the information in the note is unaudited, comments on the aggregate effect of year-end adjustments, and an explanation of matters or transactions that affect comparability or are pertinent to an understanding of the information furnished.

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Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Organization	*Organization* We are a 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 with the objective to improve the benefits of drugs for patients. Our research and development activities have required significant ongoing investment to date and are expected to continue to require significant investment. As a result, we expect to continue to incur substantial losses and negative cash flows from operations in the future. We have financed our operations primarily through cash generated from licensing, collaboration and manufacturing agreements and financing transactions. At December 31, 2014, we had approximately $262.8 million in cash and investments in marketable securities, of which $25.0 million was restricted in relation to our 12% senior secured notes, and $151.8 million in indebtedness. The indebtedness includes $125.0 million in aggregate principal amount of 12.0% senior secured notes due July 15, 2017, but excludes our long-term liability relating to the sale of future royalties. As is further described in Note 7, this royalty obligation liability will not be settled in cash.
Basis of Presentation, Principles of Consolidation and Use of Estimates	*Basis of Presentation, Principles of Consolidation and Use of Estimates* Our consolidated financial statements include the financial position, results of operations and cash flows of our wholly-owned subsidiaries: Nektar Therapeutics (India) Private Limited and Nektar Therapeutics UK, Ltd. (Nektar UK). All intercompany accounts and transactions have been eliminated in consolidation. Our 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 (loss) in the stockholders’ equity (deficit) section of the balance sheet. To date, such cumulative translation adjustments have not been significant to our consolidated financial position. Aggregate gross foreign currency transaction gains (losses) recorded in operations for the years ended December 31, 2014, 2013, and 2012 were not significant. The preparation of consolidated financial statements in conformity with U.S. generally accepted accounting principles (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 consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Accounting estimates and assumptions are inherently uncertain. Actual results could differ materially from those estimates and assumptions. On an ongoing basis, we evaluate our estimates, including those related to estimated selling prices of deliverables in collaboration agreements, estimated periods of performance, the net realizable value of inventory, the impairment of investments, the impairment of goodwill and long-lived assets, contingencies, accrued clinical trial expenses, estimated interest expense from our liability related to our sale of future royalties, stock-based compensation, and ongoing litigation, among other estimates. 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. Estimates are assessed each period and updated to reflect current information and any changes in estimates will generally be reflected in the period first identified.
Reclassifications	*Reclassifications* Certain items previously reported in specific financial statement captions have been reclassified to conform to the current period presentation. Such reclassifications do not materially impact previously reported total revenue, operating loss or net loss or total assets, liabilities or stockholders’ equity (deficit).
Cash, Cash Equivalents, and Investments, and Fair Value of Financial Instruments	*Cash, Cash Equivalents, and Investments, and Fair Value of Financial Instruments* We consider all investments in marketable securities with an original maturity of three months or less when purchased to be cash equivalents. Investments in securities with remaining maturities of less than one year, or where our intent is to use the investments to fund current operations or to make them available for current operations, are classified as short-term investments. Investments are designated as available-for-sale and are carried at fair value, with unrealized gains and losses reported in stockholders’ equity (deficit) as accumulated other comprehensive income (loss). The disclosed fair value related to our cash equivalents and investments is based primarily on the reported fair values in our period-end brokerage statements, which are based on market prices from a variety of industry standard data providers and generally represent quoted prices for similar assets in active markets or have been derived from observable market data. We independently validate these fair values using available market quotes and other information. Interest and dividends on securities classified as available-for-sale, as well as amortization of premiums and accretion of discounts to maturity, are included in interest income. Realized gains and losses and declines in value of available-for-sale securities judged to be other-than-temporary, if any, are included in other income (expense). The cost of securities sold is based on the specific identification method. Our cash, cash equivalents, and short-term investments are exposed to credit risk in the event of default by the third parties that hold or issue such assets. Our cash, cash equivalents, and short-term investments are held by financial institutions that management believes are of high credit quality and our investment policy limits investments to fixed income securities denominated and payable in U.S. dollars such as U.S. government obligations, money market instruments and funds, and corporate bonds and places restrictions on maturities and concentrations by type and issuer.
Accounts Receivable and Significant Customer Concentrations	*Accounts Receivable and Significant Customer 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 and royalties, as well as time and materials based billings from collaborative research and development agreements. When appropriate, 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 perform a regular review of our customers’ payment histories and associated credit risk. We have not experienced significant credit losses from our accounts receivable. At December 31, 2014, three different customers represented 40%, 31%, and 15%, respectively, of our accounts receivable. At December 31, 2013, three different customers represented 30%, 28%, and 28%, respectively, of our accounts receivable.
Inventory and Significant Supplier Concentrations	*Inventory and Significant Supplier Concentrations* Inventory is generally manufactured upon receipt of firm purchase orders from our collaboration partners. Inventory includes direct materials, direct labor, and manufacturing overhead and cost is determined on a first-in, first-out basis. Inventory is valued at the lower of cost or market and defective or excess inventory is written down to net realizable value based on historical experience or projected usage. Inventory related to our research and development activities is expensed when purchased. 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 contract and regulatory requirements. In certain cases, we rely on single sources of supply of one or more critical materials. Consequently, in the event that supplies are delayed or interrupted for any reason, our ability to develop and produce our drug candidates or our ability to meet our supply obligations could be significantly impaired, which could have a material adverse effect on our business, financial condition and results of operations.
Long-Lived Assets	*Long-Lived Assets* Property, plant and equipment are stated at cost. Major improvements are capitalized, while maintenance and repairs are expensed when incurred. Manufacturing, laboratory and other equipment are depreciated using the straight-line method generally over estimated useful lives of three to seven years. Leasehold improvements and buildings recorded under capital leases are depreciated using the straight-line method over the shorter of the estimated useful life or the remaining term of the lease. Goodwill represents the excess of the price paid for another entity over the fair value of the assets acquired and liabilities assumed in a business combination. We are organized in one reporting unit and evaluate the goodwill for the Company as a whole. Goodwill has an indefinite useful life and is not amortized, but instead tested for impairment annually in the fourth quarter of each year using an October 1 measurement date. We assess the impairment of long-lived assets, primarily property, plant and equipment and goodwill included in other non-current assets, whenever events or changes in business circumstances indicate that the carrying amounts of the assets may not be fully recoverable. When such events occur, we determine whether there has been an impairment in value by comparing the asset’s carrying value with its fair value, as measured by the anticipated undiscounted net cash flows of the asset. In the case of goodwill impairment, market capitalization is generally used as the measure of fair value. If an impairment in value exists, the asset is written down to its estimated fair value.
Revenue Recognition	*Revenue Recognition* Our revenue is derived from our arrangements with pharmaceutical and biotechnology collaboration partners and may result from one or more of the following: upfront and license fees, payments for contract research and development, milestone payments, manufacturing and supply payments, and royalties. Our performance obligations under our collaborations may include licensing our intellectual property, manufacturing and supply obligations, and research and development obligations. In order to account for the multiple-element arrangements, the Company identifies the deliverables included within the arrangement and evaluates which deliverables represent separate units of accounting. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver services, a right or license to use an asset, or another performance obligation. Revenue is recognized separately for each identified unit of accounting when the basic revenue recognition criteria are met: there is persuasive evidence that an arrangement exists, delivery has occurred, the price is fixed or determinable, and collection is reasonably assured. At the inception of each new multiple-element arrangement or the material modification of an existing multiple-element arrangement, we allocate all consideration received under multiple-element arrangements to all units of accounting based on the relative selling price method, generally based on our best estimate of selling price (ESP). The objective of ESP is to determine the price at which we would transact a sale if the product or service was sold on a stand-alone basis. We determine ESP for the elements in our collaboration arrangements by considering multiple factors including, but not limited to, technical complexity of the performance obligation and similarity of elements to those performed under previous arrangements. Since we apply significant judgment in arriving at the ESPs, any material change in our estimates would significantly affect the allocation of the total consideration to the different elements of a multiple element arrangement. Product sales Product sales are primarily derived from fixed price and cost-plus manufacturing and supply agreements with our collaboration partners. We have not experienced any significant returns from our customers. Royalty revenues Generally, we are entitled to royalties from our collaboration partners based on the net sales of their approved drugs that are marketed and sold in one or more countries where we hold royalty rights. We recognize royalty revenue when the cash is received or when the royalty amount to be received is estimable and collection is reasonably assured. With respect to the non-cash royalties related to sale of future royalties described at Note 7, revenue is recognized when estimable, otherwise, revenue is recognized during the period in which the related royalty report is received, which generally occurs in the quarter after the applicable product sales are made. License, collaboration and other The amount of upfront fees and other payments received by us in license and collaboration arrangements that are allocated to continuing performance obligations, such as manufacturing and supply obligations, are deferred and generally recognized ratably over our expected performance period under each respective arrangement. We make our best estimate of the period over which we expect to fulfill our performance obligations, which may include technology transfer assistance, research activities, clinical development activities, and manufacturing activities from development through the commercialization of the product. Given the uncertainties of these collaboration arrangements, significant judgment is required to determine the duration of the performance period and this estimate is periodically re-evaluated. 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 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 either on 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, approvals by health authorities, and commercial launches of drugs. Given the challenges inherent in developing and obtaining regulatory approval for drug products and in achieving commercial launches, there was substantial uncertainty whether any such milestones would be achieved at the time of execution of these licensing and collaboration agreements. In addition, we evaluated whether the development milestones meet the remaining criteria to be considered substantive. As a result of our analysis, we consider our remaining development milestones under all of our license and collaboration agreements to be substantive and, accordingly, we expect to recognize as revenue future payments received from such milestones only if and as each milestone is achieved. 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, which is generally upon completion of performance by the respective partner, 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.
Shipping and Handling Costs	*Shipping and Handling Costs* We recognize costs related to shipping and handling of product to customers in cost of goods sold.
Research and Development Expense	*Research and Development Expense* Research and development costs are expensed as incurred and include salaries, benefits and other operating costs such as outside services, supplies and allocated overhead costs. We perform research and development for our proprietary drug candidates and technology development and for certain third parties under collaboration agreements. For our proprietary drug candidates and our internal technology development programs, we invest our own funds without reimbursement from a third party. We record accruals for the estimated costs of our clinical trial activities performed by third parties. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows to our vendors. Payments under the contracts depend on factors such as the achievement of certain events, successful enrollment of patients, and completion of portions of the clinical trial or similar conditions. We generally accrue costs associated with the start-up and reporting phases of the clinical trials ratably over the estimated duration of the start-up and reporting phases. We generally accrue costs associated with the treatment phase of clinical trials based on the total estimated cost of the treatment phase on a per patient basis and we expense the per patient cost ratably over the estimated patient treatment period based on patient enrollment in the trials. In specific circumstances, such as for certain time-based costs, we recognize clinical trial expenses using a methodology that we consider to be more reflective of the timing of costs incurred. Advance payments for goods or services that will be used or rendered for future research and development activities are capitalized as prepaid expenses and recognized as expense as the related goods are delivered or the related services are performed. We base our estimates on the best information available at the time. However, additional information may become available to us which may allow us to make a more accurate estimate in future periods. In this event, we may be required to record adjustments to research and development expenses in future periods when the actual level of activity becomes more certain. Such increases or decreases in cost are generally considered to be changes in estimates and will be reflected in research and development expenses in the period first identified. During the year ended December 31, 2014, we recorded a reduction related to prior periods of approximately $4.7 million to our research and development expenses primarily related to our Beacon Phase 3 clinical trial for etirinotecan pegol.
Stock-Based Compensation	*Stock-Based Compensation* Stock-based compensation arrangements include stock option grants and restricted stock unit (RSU) awards under our equity incentive plans, as well as shares issued under our Employee Stock Purchase Plan (ESPP), through which employees may purchase our common stock at a discount to the market price. We use the Black-Scholes option pricing model for the respective grant to determine the estimated fair value of the option on the date of grant (grant date fair value) and the estimated fair value of common stock purchased under the ESPP. The Black-Scholes option pricing model requires the input of highly subjective assumptions. These variables include, but are not limited to, our stock price volatility over the term of the awards, and actual and projected employee stock option exercise behaviors. Because our employee stock options have characteristics significantly different from those of traded options, and because changes in the subjective input assumptions can materially affect the fair value estimate, in management’s opinion, the existing models may not provide a reliable single measure of the fair value of our employee stock options or common stock purchased under the ESPP. Management will continue to assess the assumptions and methodologies used to calculate the estimated fair value of stock-based compensation. Circumstances may change and additional data may become available over time, which could result in changes to these assumptions and methodologies, and which could materially impact our fair value determination. We expense the value of the portion of the option or award that is ultimately expected to vest based on the historical forfeiture rate on a straight line basis over the requisite service periods in our Consolidated Statements of Operations. For awards that vest upon the achievement of performance milestones, we estimate the vesting period based on our evaluation of the probability of achievement of each respective milestone and the related estimated date of achievement. Stock-based compensation expense for purchases under the ESPP is recognized over the respective six-month purchase period. Expense amounts are recorded in cost of goods sold, research and development expense, and general and administrative expense based on the function of the applicable employee. Stock-based compensation charges are non-cash charges and as such have no impact on our reported cash flows.
Net Loss Per Share	*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 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. During 2014, 2013 and 2012, potentially dilutive securities consisted of common shares underlying outstanding stock options and there were weighted average outstanding stock options of 21.9 million, 20.7 million and 18.8 million during the years ended December 31, 2014, 2013 and 2012, respectively.
Income Taxes	*Income Taxes* We account for income taxes under the liability method. Under this method, 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. When we establish or reduce the valuation allowance related to the deferred tax assets, our provision for income taxes will increase or decrease, respectively, in the period such determination is made. We utilize a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained upon tax authority examination, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon ultimate settlement.
Comprehensive loss	*Comprehensive loss* Comprehensive loss is the change in stockholders’ equity (deficit) from transactions and other events and circumstances other than those resulting from investments by stockholders and distributions to stockholders. Our other comprehensive income (loss) is comprised of net loss, gains and losses from the foreign currency translation of the assets and liabilities of our India and UK subsidiaries, and unrealized gains and losses on investments in available-for-sale securities.
Recent Accounting Pronouncements	*Recent Accounting Pronouncements* In May 2014, the Financial Accounting Standards Board (FASB) issued guidance codified in Accounting Standards Codification (ASC) 606, Revenue Recognition — Revenue from Contracts with Customers, which amends the guidance in former ASC 605, Revenue Recognition, and is effective for public companies for fiscal years beginning after December 15, 2016. We are currently evaluating the impact of the provisions of ASC 606. In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (ASU 2014-15). ASU 2014-15 requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. ASU 2014-15 is effective in 2016 with early adoption permitted. We do not believe the impact of adopting ASU 2014-15 on our consolidated financial statements will be significant.

Cash and Investments in Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Cash and Investments in Marketable Securities, Including Cash Equivalents and Restricted Cash

Cash and investments in marketable securities, including cash equivalents and restricted cash, are as follows (in thousands):


	Estimated Fair Value at
	December 31, 2014		December 31, 2013
Cash and cash equivalents	$	12,365	$	39,067
Short-term investments		225,459		197,959
Restricted cash		25,000		25,000

Total cash and investments in marketable securities	$	262,824	$	262,026

Portfolio of Cash and Investments in Marketable Securities

Our portfolio of cash and investments in marketable securities includes (in thousands):


	Fair Value Hierarchy Level		Estimated Fair Value at
	Fair Value Hierarchy Level		December 31, 2014		December 31, 2013
Corporate notes and bonds		2	$	182,544	$	138,515
Corporate commercial paper		2		42,915		59,444

Available-for-sale investments				225,459		197,959
Money market funds		1		11,229		26,453
Cash, including restricted cash		N/A		26,136		37,614

Total cash and investments in marketable securities			$	262,824	$	262,026

Inventory (Tables)

12 Months Ended

Dec. 31, 2014

Inventory Disclosure [Abstract]

Inventory

Inventory consists of the following (in thousands):


	December 31,
	2014		2013
Raw materials	$	2,200	$	3,947
Work-in-process		5,187		6,146
Finished goods		5,565		3,359

Inventory	$	12,952	$	13,452

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, plant and equipment consists of the following (in thousands):


	December 31,
	2014			2013
Building and leasehold improvements	$	72,228		$	71,306
Laboratory equipment		26,975			26,621
Manufacturing equipment		25,212			23,699
Furniture, fixtures and other equipment		23,451			23,235

Depreciable property, plant and equipment at cost		147,866			144,861
Less: accumulated depreciation		(93,807	)		(84,148	)

Depreciable property, plant and equipment, net		54,059			60,713
Construction-in-progress		16,309			6,261

Property, plant and equipment, net	$	70,368		$	66,974

Leases (Tables)

12 Months Ended

Dec. 31, 2014

Text Block [Abstract]

Future Minimum Payments for Capital Leases

Future minimum payments for our capital leases at December 31, 2014 are as follows (in thousands):


Years ending December 31,
2015	$	5,572
2016		4,268
2017		175

Total minimum payments required		10,015
Less: amount representing interest		(1,364	)

Present value of future minimum lease payments		8,651
Less: current portion		(4,512	)

Capital lease obligation, less current portion	$	4,139

Future Minimum Lease Payments for Operating Leases

Our future minimum lease payments for our operating leases at December 31, 2014 are as follows (in thousands):


Years ending December 31,
2015	$	4,750
2016		4,892
2017		5,037
2018		5,187
2019		5,344
2020		452

Total future minimum lease payments	$	25,662

Liability Related to Sale of Future Royalties (Tables)

12 Months Ended

Dec. 31, 2014

Text Block [Abstract]

Summary of Liability Related to Potential Future Royalties


	Year ended December 31, 2014			Period from inception to December 31, 2014
Liability related to sale of future royalties — beginning balance	$	128,520		$	—
Proceeds from sale of future royalties		—			124,000
Payments from Nektar to RPI		(7,000	)		(10,000	)
Non-cash CIMZIA^® and MIRCERA^® royalty revenue		(21,937	)		(54,783	)
Non-cash interest expense recognized		20,888			61,254

Liability related to sale of future royalties — ending balance	$	120,471		$	120,471

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2014

Equity [Abstract]

Summarization of Common Stock Shares for Issuance Under Existing Equity Compensation Plans


Plan Category	Number of Securities to be Issued Upon Exercise of Outstanding Options (a)		Weighted-Average Exercise Price of Outstanding Options (b)		Number of Securities Remaining Available for Issuance Under Equity Compensation Plans (Excluding Securities Reflected in Column(a)) (c)
Equity compensation plans approved by security holders(1)		18,601	$	10.68		2,812
Equity compensation plans not approved by security holders		3,394	$	9.52		—

Total		21,995	$	10.50		2,812

(1)	Includes shares of common stock available for future issuance under our ESPP as of December 31, 2014.

License and Collaboration Agreements (Tables)

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

License, Collaboration and Other Revenue

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


		Year Ended December 31,
Partner	Agreement	2014		2013		2012
AstraZeneca AB	MOVANTIK^TM (NKTR-118) and MOVANTIK^TM fixed-dose combination program (NKTR-119)	$	105,001	$	25,016	$	59
Roche	PEGASYS^® and MIRCERA^®		12,845		18,382		7,146
Baxter Healthcare	BAX 855 (Hemophilia)		10,258		1,702		6,238
Amgen, Inc.	Neulasta^®		5,000		5,035		5,000
Bayer Healthcare LLC	BAY41-6551 (Amikacin Inhale)		4,717		15,293		2,971
Affymax, Inc.	OMONTYS^®		—		7,149		2,829
Other			15,468		8,295		5,884

License, collaboration and other revenue		$	153,289	$	80,872	$	30,127

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation Expense

Stock-based compensation expense was recognized as follows (in thousands):


	Year Ended December 31,
	2014		2013		2012
Cost of goods sold	$	1,161	$	1,297	$	1,496
Research and development		7,528		7,910		7,082
General and administrative		8,328		8,501		7,621

Total stock-based compensation	$	17,017	$	17,708	$	16,199

Black-Scholes Option-Pricing Model Assumptions Used to Calculate Fair Value of Employee Stock Options

The following tables list the Black-Scholes option-pricing model assumptions used to calculate the fair value of employee and director stock options.


	Year Ended December 31, 2014			Year Ended December 31, 2013			Year Ended December 31, 2012
Average risk-free interest rate		1.6	%		0.9	%		0.9	%
Dividend yield		0.0	%		0.0	%		0.0	%
Average volatility factor		51.6	%		61.2	%		62.2	%
Average weighted average expected life		5.2 years			5.2 years			5.0 years

Stock Option Activity Under Equity Incentive Plans

The table below presents a summary of stock option activity under our equity incentive plans (in thousands, except for price per share and contractual life information):


	Number of Shares			Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Life (in Years)		Aggregate Intrinsic Value(1)
Outstanding at December 31, 2013		20,655		$	9.06
Options granted		7,713			13.96
Options exercised		(4,852	)		9.43
Options forfeited & canceled		(1,521	)		11.89

Outstanding at December 31, 2014		21,995		$	10.50		4.96	$	112,549

Vested and expected to vest at December 31, 2014		21,338		$	10.41		4.89	$	111,071
Exercisable at December 31, 2014		13,007		$	8.90		3.47	$	85,839

(1)	Aggregate intrinsic value represents the difference between the exercise price of the option and the closing market price of our common stock on December 31, 2014.

- Definition

Tabular disclosure of components of a stock option or other award plan under which equity-based compensation is awarded to employees, typically comprised of the amount of unearned compensation (deferred compensation cost), compensation expense, and changes in the quantity and fair value of the shares (or other type of equity) granted, exercised, forfeited, and issued and outstanding pertaining to that plan. Disclosure may also include nature and general terms of such arrangements that existed during the period and potential effects of those arrangements on shareholders, effect of compensation cost arising from equity-based payment arrangements on the income statement, method of estimating the fair value of the goods or services received, or the fair value of the equity instruments granted, during the period, cash flow effects resulting from equity-based payment arrangements and, for registrants that accelerate vesting of out of the money share options, reasons for the decision to accelerate.

+ References+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Loss Before (Benefit) Provision for Income Taxes

Loss before (benefit) provision for income taxes includes the following components (in thousands):


	Year Ended December 31,
	2014			2013			2012
Domestic	$	(56,414	)	$	(161,068	)	$	(174,258	)
Foreign		1,986			1,300			2,809

Loss before (benefit) provision for income taxes	$	(54,428	)	$	(159,768	)	$	(171,449	)

(Benefit) Provision for Income Taxes

The (benefit) provision for income taxes consists of the following (in thousands):


	Year Ended December 31,
	2014			2013			2012
Current:
Federal	$	—		$	—		$	(137	)
State		1			1			1
Foreign		(482	)		1,838			1,029

Total Current		(481	)		1,839			893

Deferred:
Federal		—			422			(422	)
State		—			49			(49	)
Foreign		(31	)		(65	)		(16	)

Total Deferred		(31	)		406			(487	)

(Benefit) provision for income taxes	$	(512	)	$	2,245		$	406

Income Tax Provision Related to Continuing Operations

Income tax provision related to continuing operations differs from the amount computed by applying the statutory income tax rate of 35% to pretax loss as follows (in thousands):


	Year Ended December 31,
	2014			2013			2012
U.S. federal provision (benefit)
At statutory rate	$	(19,050	)	$	(55,919	)	$	(60,007	)
State taxes		1			50			(48	)
Change in valuation allowance		11,831			55,042			47,349
Non-cash interest expense on liability related to sale of future royalties		7,311			7,808			6,320
Stock-based compensation		2,832			271			236
Foreign tax inclusion		—			—			6,510
Foreign tax differential		(17	)		(20	)		(227	)
Research credits		(2,933	)		(6,273	)		(591	)
Other		(487	)		1,286			864

(Benefit) provision for income taxes	$	(512	)	$	2,245		$	406

Significant Components of Deferred Tax Assets and Liabilities

Significant components of our deferred tax assets for federal and state income taxes are as follows (in thousands):


	December 31,
	2014			2013
Deferred tax assets:
Net operating loss carryforwards	$	423,776		$	391,385
Research and other credits		66,666			61,707
Deferred revenue		29,758			35,588
Stock-based compensation		21,948			25,962
Sale of future royalties		20,153			28,057
Capitalized research expenses		14,795			17,687
Reserves and accruals		8,288			14,685
Property, plant and equipment		8,264			8,580
Other		2,218			2,539

Deferred tax assets before valuation allowance		595,866			586,190
Valuation allowance for deferred tax assets		(595,690	)		(586,040	)

Total deferred tax assets		176			150

Total deferred tax liabilities		—			—

Net deferred tax assets	$	176		$	150

Unrecognized Tax Benefits

We have the following activity relating to unrecognized tax benefits (in thousands):


	December 31,
	2014			2013		2012
Beginning balance	$	16,363		$	14,067	$	13,576
Tax positions related to current year
Additions:
Federal		502			477		289
State		6,141			381		302
Reductions		—			—		—
Tax positions related to prior year
Additions:
Federal		—			636		37
State		5,258			—		—
Foreign		—			802		—
Reductions — foreign		(742	)		—		—
Settlements		—			—		—
Lapses in statute of limitations		—			—		(137	)

Ending balance	$	27,522		$	16,363	$	14,067

Segment Reporting (Tables)

12 Months Ended

Dec. 31, 2014

Segment Reporting [Abstract]

Revenue by Geographic Area

Revenue by geographic area is based on the locations of our partners. The following table sets forth revenue by geographic area (in thousands):


	Year Ended December 31,
	2014		2013		2012
United States	$	32,514	$	42,535	$	34,591
Europe		168,193		106,386		46,600

Total revenue	$	200,707	$	148,921	$	81,191

Selected Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2014

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Data


	Fiscal Year 2014											Fiscal Year 2013
	Q1			Q2			Q3		Q4			Q1			Q2			Q3			Q4
Product sales	$	5,795		$	5,802		$	6,096	$	7,460		$	11,810		$	10,324		$	14,672		$	8,040
Total revenue	$	19,771		$	28,513		$	132,871	$	19,551		$	23,004		$	33,862		$	60,909		$	31,146
Cost of goods sold	$	7,907		$	5,108		$	9,220	$	6,298		$	11,661		$	5,011		$	12,877		$	8,960
Research and development expenses	$	38,338		$	36,702		$	34,200	$	38,494		$	45,618		$	52,230		$	43,914		$	48,248
Operating income (loss)	$	(36,402	)	$	(22,916	)	$	80,321	$	(37,488	)	$	(45,106	)	$	(32,605	)	$	(6,525	)	$	(35,894	)
Net income (loss)	$	(46,201	)	$	(32,637	)	$	70,605	$	(45,683	)	$	(55,063	)	$	(42,748	)	$	(16,543	)	$	(47,659	)
Net income (loss) per share(1)
Basic	$	(0.37	)	$	(0.26	)	$	0.55	$	(0.35	)	$	(0.48	)	$	(0.37	)	$	(0.14	)	$	(0.41	)
Diluted	$	(0.37	)	$	(0.26	)	$	0.53	$	(0.35	)	$	(0.48	)	$	(0.37	)	$	(0.14	)	$	(0.41	)

(1)	Quarterly loss per share amounts may not total to the year-to-date loss per share due to rounding.

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended							1 Months Ended	12 Months Ended
	Dec. 31, 2014 Reporting_Unit Customer	Dec. 31, 2013 Customer	Dec. 31, 2014 Stock Options [Member]	Dec. 31, 2013 Stock Options [Member]	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2014 Minimum [Member]	Dec. 31, 2014 Maximum [Member]	Jul. 31, 2012 12% Senior Secured Notes Due July 2017 [Member]	Dec. 31, 2014 12% Senior Secured Notes Due July 2017 [Member]	Jul. 11, 2012 12% Senior Secured Notes Due July 2017 [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Cash and investments in marketable securities	$ 262,824,000	$ 262,026,000
Indebtedness	151,800,000
Senior secured notes, issued	125,000,000	125,000,000								125,000,000
Senior secured notes, interest rate									12.00%	12.00%
Senior secured notes, maturity date								Jul. 15, 2017	Jul. 15, 2017
Restricted cash	25,000,000								25,000,000
Maximum maturity term of investments in marketable securities to be considered as cash equivalents	Three months
Maturity term of investments considered as short-term	Less than one year
Number of customers accounted for major accounts receivable	3	3
Percentage of accounts receivable customers one	40.00%	30.00%
Percentage of accounts receivable customers two	31.00%	28.00%
Percentage of accounts receivable customers three	15.00%	28.00%
Property and equipment estimated useful lives						3	7
Number of reporting unit evaluated for goodwill	1
Reduction of prior periods research and development expenses	$ 4,700,000
Weighted average diluted securities excluded from diluted net loss per share			21.9	20.7	18.8
Minimum percentage of amount realized upon ultimate settlement	50.00%

Cash and Investments in Marketable Securities - Cash and Investments in Marketable Securities, Including Cash Equivalents and Restricted Cash (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 11, 2012	Dec. 31, 2011
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and cash equivalents	$ 12,365	$ 39,067	$ 25,437		$ 15,312
Short-term investments	225,459	197,959
Restricted cash	25,000	25,000		25,000
Total cash and investments in marketable securities	$ 262,824	$ 262,026

- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References+ Details

Cash and Investments in Marketable Securities - Additional Information (Detail) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2012 12% Senior Secured Notes Due July 2017 [Member]	Dec. 31, 2014 12% Senior Secured Notes Due July 2017 [Member]	Jul. 11, 2012 12% Senior Secured Notes Due July 2017 [Member]
Cash and Investments in Marketable Securities [Line Items]
Maximum maturity term for debt securities investment	Two years or less
Weighted average maturity term for debt securities investment	One year or less
Available-for-sale securities, sold	$ 21,700,000	$ 2,900,000	$ 5,400,000
Restricted cash	25,000,000				25,000,000
Senior secured notes, interest rate					12.00%	12.00%
Senior secured notes, maturity date				Jul. 15, 2017	Jul. 15, 2017
Level 1 to level 2 transfers	0	0
Level 2 to level 1 transfers	0	0
Letter of credit	$ 2,400,000	$ 2,400,000

Cash and Investments in Marketable Securities - Portfolio of Cash and Investments in Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	$ 225,459	$ 197,959
Cash, including restricted cash	26,136	37,614
Total cash and investments in marketable securities	262,824	262,026
Corporate Notes and Bonds [Member] \| Fair Value Hierarchy Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	182,544	138,515
Corporate Commercial Paper [Member] \| Fair Value Hierarchy Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	42,915	59,444
Money Market Funds [Member] \| Fair Value Hierarchy Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 11,229	$ 26,453

Inventory - Inventory (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials	$ 2,200	$ 3,947
Work-in-process	5,187	6,146
Finished goods	5,565	3,359
Inventory	$ 12,952	$ 13,452

- Definition

Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

+ References+ Details

Property, Plant and Equipment - Property, Plant and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Depreciable property and equipment at cost	$ 147,866	$ 144,861
Less: accumulated depreciation	(93,807)	(84,148)
Depreciable property, plant and equipment, net	54,059	60,713
Construction-in-progress	16,309	6,261
Property plant and equipment, net	70,368	66,974
Building and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Depreciable property and equipment at cost	72,228	71,306
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciable property and equipment at cost	26,975	26,621
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciable property and equipment at cost	25,212	23,699
Furniture, Fixtures and Other Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciable property and equipment at cost	$ 23,451	$ 23,235

Property, Plant and Equipment - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 11.7	$ 13.0	$ 13.8
Obligation related to purchase of equipment	7.2
Obligation related to purchase of equipment liability payable term	3 years
Land and Building [Member]
Property, Plant and Equipment [Line Items]
Impairment charge			$ 1.7

Senior Secured Notes - Additional Information (Detail) (USD $)	12 Months Ended			1 Months Ended		12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Jul. 11, 2012	Jul. 31, 2012 Convertible Subordinated Notes [Member]	Jul. 31, 2012 12% Senior Secured Notes Due July 2017 [Member]	Dec. 31, 2014 12% Senior Secured Notes Due July 2017 [Member]	Jul. 11, 2012 12% Senior Secured Notes Due July 2017 [Member]	Dec. 31, 2014 July 1, 2015 through June 30, 2017 [Member]	Dec. 31, 2014 12% Senior Secured Notes Due July 2017 [Member]	Dec. 31, 2014 12% Senior Secured Notes Due July 2017 [Member]
Line of Credit Facility [Line Items]
Senior secured notes, issued	$ 125,000,000	$ 125,000,000					$ 125,000,000
Maturity date of senior secured notes					Jul. 15, 2017	Jul. 15, 2017			Jul. 15, 2017
Retirement of convertible subordinated notes				42,500,000
Interest rate						12.00%	12.00%			12.00%
Issuance costs					4,500,000
Convertible subordinated notes remaining			172,400,000
Maturity date of convertible subordinated notes	Sep. 28, 2012
Restricted cash	25,000,000	25,000,000	25,000,000
Minimum Cash Requirement (Jul 1, 2015 through June 30, 2017)								25,000,000
Percentage of repurchase of notes on principal amount of notes	101.00%
Percentage of repurchase of notes on principal amount of notes	100.00%
Senior Secured Notes carrying amount										$ 125,000,000

Leases - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2009 Pfizer, Inc. [Member] sqft
Leases [Line Items]
Percentage ceiling on rent increases, annually, capital lease	3.00%
San Carlos facility capital leases, termination date	Oct. 05, 2016
Future minimum rental receipts under the San Carlos facility subleases	$ 4.8
Book value of assets, gross	2.7	2.3
Net book value of assets	1.2	1.0
Operating sublease				126,285
Operating Sublease term commenced start date	August 2010
Operating Sublease term commenced period	114 months
Operating Sublease term commenced end date	January 31, 2020
Rent expense for operating leases	$ 3.2	$ 2.9	$ 2.8

Leases - Future Minimum Payments for Capital Leases (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Leases [Abstract]
2015	$ 5,572
2016	4,268
2017	175
Total minimum payments required	10,015
Less: amount representing interest	(1,364)
Present value of future minimum lease payments	8,651
Present value of future minimum lease payments	8,651
Less: current portion	(4,512)	(3,536)
Capital lease obligation, less current portion	$ 4,139	$ 8,049

- Definition

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid more than one year (or one operating cycle, if longer) after the balance sheet date.

+ References+ Details

Leases - Future Minimum Lease Payments for Operating Leases (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014
Leases [Abstract]
2015	$ 4,750
2016	4,892
2017	5,037
2018	5,187
2019	5,344
2020	452
Total future minimum lease payments	$ 25,662

Liability Related to Sale of Future Royalties - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended	1 Months Ended		0 Months Ended	12 Months Ended
	Dec. 31, 2014	Mar. 31, 2013 Milestone Scenario One [Member]	Mar. 31, 2014 Milestone Scenario Two [Member]	Feb. 24, 2012 Purchase and Sale Agreement with RPI [Member]	Dec. 31, 2014 CIMZIA and MIRCERA [Member]	Dec. 31, 2013 CIMZIA and MIRCERA [Member]	Dec. 31, 2012 CIMZIA and MIRCERA [Member]
Liability Related to Sale of Future Royalties [Line Items]
Proceeds from sale of royalty rights				$ 124.0
Transaction costs related to sale of potential future royalties				4.4
Payment made for milestone not achieved year one		3.0
Payment made for milestone not achieved year two			7.0
Royalty agreement contingent payment description	As a result of worldwide net sales of MIRCERA for the 12 month periods ended on December 31, 2013 and 2012 not reaching certain minimum thresholds.
Non-cash royalties from net sales					$ 21.9	$ 22.1	$ 10.8
Annual interest rate	17.00%

Liability Related to Sale of Future Royalties - Summary of Liability Related to Potential Future Royalties (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended			34 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Other Liabilities Disclosure [Abstract]
Liability related to sale of future royalties-beginning balance	$ 128,520
Proceeds from sale of future royalties				124,000
Payments from Nektar to RPI	(7,000)			(10,000)
Non-cash CIMZIA® and MIRCERA®royalty revenue	(21,937)	(22,055)	(10,791)	(54,783)
Non-cash interest expense recognized	20,888	22,309	18,057	61,254
Liability related to sale of future royalties - ending balance	$ 120,471	$ 128,520		$ 120,471

Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Loss Contingencies [Line Items]
Royalty expense	$ 3,400,000	$ 4,100,000	$ 2,900,000
Purchase commitments related to contract manufacturing, clinical development and certain other items	16,900,000
Indemnification Obligation [Member]
Loss Contingencies [Line Items]
Indemnification Obligations, liabilities	0	0
Securities Related Claims [Member]
Loss Contingencies [Line Items]
Obligations under Director and Officer Indemnifications per incident	1,000,000
Non-Securities Related Claims [Member]
Loss Contingencies [Line Items]
Obligations under Director and Officer Indemnifications per incident	500,000
Merger and Acquisition Related Claims [Member]
Loss Contingencies [Line Items]
Obligations under Director and Officer Indemnifications per incident	$ 1,500,000

- Definition

Minimum amount to be expended to satisfy the terms of arrangements in which the entity has agreed to expend funds to procure goods or services, excluding long-term purchase commitments or unconditional purchase obligations.

+ References+ Details

Stockholders' Equity - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended																0 Months Ended	12 Months Ended
	Jan. 28, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014 2012 Performance Incentive Plan [Member]	Dec. 31, 2014 2012 Performance Incentive Plan [Member] Employee [Member]	Dec. 31, 2014 2012 Performance Incentive Plan [Member] Director [Member]	Dec. 31, 2014 2000 Non-Officer Equity Incentive Plan [Member]	Dec. 31, 2014 Restricted Stock Units [Member]	Dec. 31, 2013 Restricted Stock Units [Member]	Dec. 31, 2012 Restricted Stock Units [Member]	Dec. 31, 2014 Employee Stock Purchase Plan [Member]	Dec. 31, 2014 Maximum [Member]	Dec. 31, 2014 Maximum [Member] 2012 Performance Incentive Plan [Member]	Dec. 31, 2014 Series A Preferred Stock [Member]	Dec. 31, 2013 Series A Preferred Stock [Member]	Dec. 31, 2011 Series A Preferred Stock [Member]	Jan. 28, 2014 Common Shares [Member]	Dec. 31, 2014 Common Shares [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized		10,000,000	10,000,000
Preferred stock, par value		$ 0.0001	$ 0.0001
Preferred stock, shares designated		0	0												0	0	3,100,000
Preferred stock, shares issued		0	0
Preferred stock, shares outstanding		0	0
Common stock, shares issued																		9,775,000	9,775,000
Proceeds from sale of common stock	$ 117,200,000
Legal, accounting fees, filing fees and other offering expenses																		600,000
Underwriting commission and discounts																		7,500,000
Common stock, shares reserved for issuance in equity compensation plans																			24,806,565
Additional new shares available for award grants					5,300,000
Service period for stock options granted						4 years	1 year
Number of common stock shares available for stock options grants														10,347,140
Share-based compensation plan's share limit reduction for every one restricted stock unit granted					1.5
Awards granted									0	0	0
Restricted Stock Units outstanding		0
Maximum term of stock options under equity incentive plans					8 years
Maximum term of stock options under equity incentive plans								8 years
Common stock, shares authorized		300,000,000	300,000,000									2,500,000
Percentage of purchase price of stock												85.00%
Maximum 401(k) per employee, percentage of annual salary		60.00%
Matching 401(k) employer contribution, maximum amount													3,000
Compensation expense in connection with 401(k) retirement plan		$ 900,000	$ 1,000,000	$ 900,000
Severance payment period for executives		12 months
Severance payment period for employees		6 months
Cash severance payment for chief executive officer		24 months base salary plus annual target incentive pay

Stockholders' Equity - Summarization of Common Stock Shares for Issuance Under Existing Equity Compensation Plans (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Securities to be Issued Upon Exercise of Outstanding Options	21,995
Number of Securities Remaining Available for Issuance Under Equity Compensation Plans (Excluding Securities Reflected in Column)	2,812
Weighted-Average Exercise Price of Outstanding Options	$ 10.50
Equity Compensation Plans Approved by Security Holders [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Securities to be Issued Upon Exercise of Outstanding Options	18,601
Number of Securities Remaining Available for Issuance Under Equity Compensation Plans (Excluding Securities Reflected in Column)	2,812
Weighted-Average Exercise Price of Outstanding Options	$ 10.68
Equity Compensation Plans Not Approved by Security Holders [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Securities to be Issued Upon Exercise of Outstanding Options	3,394
Weighted-Average Exercise Price of Outstanding Options	$ 9.52

License and Collaboration Agreements - License, Collaboration and Other Revenue (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	$ 153,289	$ 80,872	$ 30,127
AstraZeneca AB [Member] \| MOVANTIKTM (NKTR-118) and MOVANTIKTM fixed-dose combination program (NKTR-119) [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	105,001	25,016	59
Roche [Member] \| PEGASYS and MIRCERA [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	12,845	18,382	7,146
Baxter Healthcare [Member] \| BAX 855 (Hemophilia) [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	10,258	1,702	6,238
Amgen, Inc. [Member] \| Neulasta [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	5,000	5,035	5,000
Bayer Healthcare LLC [Member] \| BAY41-6551 (Amikacin Inhale) [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	4,717	15,293	2,971
Affymax, Inc. [Member] \| OMONTYS [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue		7,149	2,829
Other [Member]
License And Collaboration Agreements [Line Items]
License, collaboration and other revenue	$ 15,468	$ 8,295	$ 5,884

License and Collaboration Agreements - Additional Information (Detail) (USD $)	12 Months Ended				1 Months Ended		12 Months Ended	1 Months Ended				1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended	3 Months Ended	0 Months Ended					12 Months Ended	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014 MOVANTIK [Member] US and EU Commercial Launch [Member]	Dec. 31, 2014 MOVANTIK [Member] United States [Member]	Dec. 31, 2014 MOVANTIK [Member] European Union [Member]	Dec. 31, 2009 Roche [Member] License Extension Option [Member]	Feb. 29, 2012 Roche [Member] MIRCERA [Member]	Dec. 31, 2014 Roche [Member] MIRCERA [Member]	Feb. 29, 2012 Roche [Member] MIRCERA [Member] Performance-based Milestone Payments [Member]	Feb. 29, 2012 Roche [Member] MIRCERA [Member] Upfront Payment Arrangement in 2007 [Member]	Dec. 31, 2014 Roche [Member] PEGASYS [Member]	Dec. 31, 2014 Roche [Member] PEGASYS and MIRCERA [Member]	Jun. 30, 2013 Bayer Healthcare LLC [Member]	Dec. 31, 2014 Bayer Healthcare LLC [Member]	Dec. 31, 2014 Bayer Healthcare LLC [Member] Performance-based Milestone Payments [Member]	Dec. 31, 2007 Bayer Healthcare LLC [Member] Upfront Payment Arrangement in 2007 [Member]	Jun. 30, 2014 Ophthotech Corporation [Member] Fovista [Member]	Dec. 31, 2014 Ophthotech Corporation [Member] Fovista [Member]	Dec. 31, 2009 AstraZeneca AB [Member] MOVANTIKTM (NKTR-118) and MOVANTIKTM fixed-dose combination program (NKTR-119) [Member] Upfront Payment Arrangement in 2007 [Member]	Sep. 16, 2014 AstraZeneca AB [Member] MOVANTIK [Member]	Dec. 31, 2014 AstraZeneca AB [Member] MOVANTIK [Member]	Sep. 16, 2014 AstraZeneca AB [Member] MOVANTIK [Member]	Sep. 16, 2014 AstraZeneca AB [Member] MOVANTIK [Member] Pre-approval Cardiovascular Safety Study Not Required [Member]	Dec. 31, 2014 AstraZeneca AB [Member] Movantik Fixed-dose Combination Program [Member]	Dec. 31, 2014 Baxter Healthcare [Member] BAX 855 (Hemophilia) [Member]	Dec. 31, 2010 Amgen, Inc. [Member]	Dec. 31, 2014 Amgen, Inc. [Member]	Dec. 31, 2013 Affymax, Inc. [Member] OMONTYS [Member]	Dec. 31, 2014 Other [Member]
Deferred Revenue Arrangement [Line Items]
Potential future additional payments for development milestones	$ 130,300,000												$ 50,000,000				$ 9,500,000							$ 20,000,000				$ 53,800,000
Received upfront and milestone payments					31,000,000			22,000,000	5,000,000					30,000,000	40,000,000	19,750,000		125,000,000	70,000,000						50,000,000
Contingent payments receivable based on development events regulatory to be pursued and completed solely by others		140,000,000	100,000,000	40,000,000																140,000,000			75,000,000
Contingent payments received based on development events																						35,000,000
Potential reduction in U.S. royalty rate for repayment																			2.00%
Percentage of post approval study costs to repay																			33.00%
Maximum potential reduction in royalties																					35,000,000
Deferred revenue							10,700,000			5,100,000	4,600,000		20,800,000				18,900,000							0		29,200,000
Allocated consideration						27,000,000
Consideration received for product delivered in 2013							18,600,000
Development milestones achieved																								8,000,000				9,000,000
Development milestone achieved in 2013														10,000,000
Payment made to Bayer for cost of Phase 3 clinical trial												10,000,000
Deferred revenue recognized																											$ 6,700,000

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 17,017	$ 17,708	$ 16,199
Cost of Goods Sold [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	1,161	1,297	1,496
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	7,528	7,910	7,082
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	$ 8,328	$ 8,501	$ 7,621

Stock-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation costs	$ 51.9
Recognized over a weighted-average period	2 years 1 month 6 days
Dividend yield	0.00%	0.00%	0.00%
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield			0.00%
Weighted-average grant-date fair value	$ 6.50	$ 4.95	$ 3.92
Total intrinsic value of options exercised	25.9	4.5	1.9
Estimated fair value of options vested	$ 15.2	$ 14.1	$ 15.7

Stock-Based Compensation - Black-Scholes Option-Pricing Model Assumptions Used to Calculate Fair Value of Employee Stock Options (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Average risk-free interest rate	1.60%	0.90%	0.90%
Dividend yield	0.00%	0.00%	0.00%
Average volatility factor	51.60%	61.20%	62.20%
Average weighted average expected life	5 years 2 months 12 days	5 years 2 months 12 days	5 years

Stock-Based Compensation - Stock Option Activity Under Equity Incentive Plans (Detail) (Stock Options [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning balance	20,655
Number of Shares, Options granted	7,713
Number of Shares, Options exercised	(4,852)
Number of Shares, Options forfeited and canceled	(1,521)
Number of Shares, Outstanding, Ending balance	21,995
Number of Shares, Vested and Expected to Vest	21,338
Number of Shares, Exercisable	13,007
Weighted-Average Exercise Price per Share, Outstanding, Beginning balance	$ 9.06
Weighted-Average Exercise Price per Share, Options granted	$ 13.96
Weighted-Average Exercise Price per Share, Options exercised	$ 9.43
Weighted-Average Exercise Price per Share, Options forfeited and Canceled	$ 11.89
Weighted-Average Exercise Price per Share, Outstanding, Ending balance	$ 10.50
Weighted-Average Exercise Price per Share, Vested and expected to vest	$ 10.41
Weighted-Average Exercise Price per Share, Exercisable	$ 8.90
Weighted-Average Remaining Contractual Life, Outstanding	4 years 11 months 16 days
Weighted-Average Remaining Contractual Life, Vested and expected to Vest	4 years 10 months 21 days
Weighted-Average Remaining Contractual Life, Exercisable	3 years 5 months 19 days
Aggregate Intrinsic Value, Outstanding	$ 112,549
Aggregate Intrinsic Value, Vested and expected to Vest	111,071
Aggregate Intrinsic Value, Exercisable	$ 85,839

Income Taxes - Loss Before (Benefit) Provision for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Domestic	$ (56,414)	$ (161,068)	$ (174,258)
Foreign	1,986	1,300	2,809
Loss before (benefit) provision for income taxes	$ (54,428)	$ (159,768)	$ (171,449)

Income Taxes - (Benefit) Provision for Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current:
Federal			$ (137)
State	1	1	1
Foreign	(482)	1,838	1,029
Total Current	(481)	1,839	893
Deferred:
Federal	0	422	(422)
State		49	(49)
Foreign	(31)	(65)	(16)
Total Deferred	(31)	406	(487)
(Benefit) provision for income taxes	$ (512)	$ 2,245	$ 406

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
Income Taxes - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Real Estate Acquired Through Foreclosure Under Forward Purchase Agreements [Line Items]
Statutory income tax rate	35.00%
Increase in valuation allowance	$ 9,700,000	$ 51,800,000
Valuation allowance related to stock-based compensation and exercises prior to the implementation of ASC 515 and 718	35,600,000	35,600,000
Deferred U.S. income taxes	0	422,000	(422,000)
Income taxes have not been provided on a cumulative total	3,900,000
Income tax research credits	2,933,000	6,273,000	591,000
Federal orphan drug credits	17,700,000
Federal orphan drug credits, expiration year	2026
Unrecognized tax benefits, period may increase or decrease due to tax examination	Next twelve months
Federal [Member]
Real Estate Acquired Through Foreclosure Under Forward Purchase Agreements [Line Items]
Net operating loss carryforward for income tax	1,131,800,000
Net operating loss carryforward, expiration year	2018
Income tax research credits	40,000,000
Income tax research credits, expiration year	2019
State [Member]
Real Estate Acquired Through Foreclosure Under Forward Purchase Agreements [Line Items]
Net operating loss carryforward for income tax	709,200,000
Net operating loss carryforward, expiration year	2015
Amounts included in state net operating losses not MLTN	124,600,000
Income tax research credits	$ 22,600,000

Income Taxes - Income Tax Provision Related to Continuing Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
U.S. federal provision (benefit)
At statutory rate	$ (19,050)	$ (55,919)	$ (60,007)
State taxes	1	50	(48)
Change in valuation allowance	11,831	55,042	47,349
Non-cash interest expense on liability related to sale of future royalties	7,311	7,808	6,320
Stock-based compensation	2,832	271	236
Foreign tax inclusion			6,510
Foreign tax differential	(17)	(20)	(227)
Research credits	(2,933)	(6,273)	(591)
Other	(487)	1,286	864
(Benefit) provision for income taxes	$ (512)	$ 2,245	$ 406

Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Net operating loss carryforwards	$ 423,776	$ 391,385
Research and other credits	66,666	61,707
Deferred revenue	29,758	35,588
Stock-based compensation	21,948	25,962
Sale of future royalties	20,153	28,057
Capitalized research expenses	14,795	17,687
Reserves and accruals	8,288	14,685
Property, plant and equipment	8,264	8,580
Other	2,218	2,539
Deferred tax assets before valuation allowance	595,866	586,190
Valuation allowance for deferred tax assets	(595,690)	(586,040)
Total deferred tax assets	176	150
Total deferred tax liabilities	0	0
Net deferred tax assets	$ 176	$ 150

Income Taxes - Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Beginning balance	$ 16,363	$ 14,067	$ 13,576
Reductions	0	0	0
Settlements	0	0	0
Lapses in statute of limitations			(137)
Ending balance	27,522	16,363	14,067
Federal [Member]
Income Tax Contingency [Line Items]
Tax positions related to current year, Additions	502	477	289
Tax positions related to prior year, Additions		636	37
State [Member]
Income Tax Contingency [Line Items]
Tax positions related to current year, Additions	6,141	381	302
Tax positions related to prior year, Additions	5,258
Foreign [Member]
Income Tax Contingency [Line Items]
Tax positions related to prior year, Additions		802
Reductions	$ (742)

Segment Reporting - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Sales Information [Line Items]
Number of operating business segment	1
Number of components within business segment	2
Property and equipment, net	$ 70,368	$ 66,974
United States [Member]
Sales Information [Line Items]
Property and equipment, net	63,700	57,300
Percentage of net book value of property and equipment	90.00%	88.00%
India [Member]
Sales Information [Line Items]
Property and equipment, net	$ 6,700	$ 7,700
Percentage of net book value of property and equipment	10.00%	12.00%
Revenue [Member] \| AstraZeneca [Member]
Sales Information [Line Items]
Percentage revenue from clients	52.00%	17.00%
Revenue [Member] \| UCB [Member]
Sales Information [Line Items]
Percentage revenue from clients	16.00%	21.00%	30.00%
Revenue [Member] \| Roche [Member]
Sales Information [Line Items]
Percentage revenue from clients	11.00%	28.00%	23.00%
Revenue [Member] \| Bayer [Member]
Sales Information [Line Items]
Percentage revenue from clients		10.00%
Revenue [Member] \| Affymax, Inc. [Member]
Sales Information [Line Items]
Percentage revenue from clients			11.00%

Segment Reporting - Revenue by Geographic Area (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue by geographic area
Total revenue	$ 19,551	$ 132,871	$ 28,513	$ 19,771	$ 31,146	$ 60,909	$ 33,862	$ 23,004	$ 200,707	$ 148,921	$ 81,191
Reportable Geographical Components [Member] \| United States [Member]
Revenue by geographic area
Total revenue									32,514	42,535	34,591
Reportable Geographical Components [Member] \| European [Member]
Revenue by geographic area
Total revenue									$ 168,193	$ 106,386	$ 46,600

Selected Quarterly Financial Data - Quarterly Financial Data (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Product sales	$ 7,460	$ 6,096	$ 5,802	$ 5,795	$ 8,040	$ 14,672	$ 10,324	$ 11,810	$ 25,152	$ 44,846	$ 35,399
Total revenue	19,551	132,871	28,513	19,771	31,146	60,909	33,862	23,004	200,707	148,921	81,191
Cost of goods sold	6,298	9,220	5,108	7,907	8,960	12,877	5,011	11,661	28,533	38,509	30,428
Research and development expenses	38,494	34,200	36,702	38,338	48,248	43,914	52,230	45,618	147,734	190,010	148,675
Operating income (loss)	(37,488)	80,321	(22,916)	(36,402)	(35,894)	(6,525)	(32,605)	(45,106)	(16,485)	(120,130)	(141,201)
Net income (loss)	$ (45,683)	$ 70,605	$ (32,637)	$ (46,201)	$ (47,659)	$ (16,543)	$ (42,748)	$ (55,063)	$ (53,916)	$ (162,013)	$ (171,855)
Net income (loss) per share
Basic	$ (0.35)	$ 0.55	$ (0.26)	$ (0.37)	$ (0.41)	$ (0.14)	$ (0.37)	$ (0.48)
Diluted	$ (0.35)	$ 0.53	$ (0.26)	$ (0.37)	$ (0.41)	$ (0.14)	$ (0.37)	$ (0.48)

Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Stock issuance costs	$ 617

Consolidated Statements of Cash Flows (Parenthetical) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Statement of Cash Flows [Abstract]
Future royalties transaction costs	$ 4.4
Senior secured notes issuance costs	$ 4.5