Orexigen Therapeutics (OREX) 10-K 27 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 23, 2015	Jun. 30, 2014
Document Information [Line Items]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	OREX
Entity Registrant Name	Orexigen Therapeutics, Inc.
Entity Central Index Key	1382911
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		123,727,546
Entity Public Float			$711

BALANCE_SHEETS

BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$104,243	$98,121
Accounts receivable	2,571	77
Investment securities, available-for-sale	101,294	78,875
Inventory	1,198
Deferred tax asset	547
Prepaid expenses and other current assets	1,473	1,209
Total current assets	211,326	178,282
Property and equipment, net	857	630
Other long-term assets	621	1,032
Restricted cash	177	177
Total assets	212,981	180,121
Current liabilities:
Accounts payable	4,243	4,787
Accrued clinical trial expenses	10,690	7,886
Accrued expenses	6,552	6,751
Deferred revenue, current portion	8,229	3,429
Total current liabilities	29,714	22,853
Long-term convertible debt	83,908	80,031
Deferred revenue, less current portion	76,114	35,143
Deferred tax liabilities	547
Other long-term liabilities	354	232
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value, 10,000,000 shares authorized at December 31, 2014 and 2013, no shares issued and outstanding at December 31, 2014 and 2013
Common stock, $0.001 par value, 300,000,000 shares authorized at December 31, 2014 and 2013; 123,460,598 and 104,970,200 shares issued and outstanding at December 31, 2014 and 2013, respectively	123	105
Additional paid-in capital	574,247	556,235
Accumulated other comprehensive loss	-26	-3
Accumulated deficit	-552,000	-514,475
Total stockholders' equity	22,344	41,862
Total liabilities and stockholders' equity	$212,981	$180,121

BALANCE_SHEETS_Parenthetical

BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	123,460,598	104,970,200
Common stock, shares outstanding	123,460,598	104,970,200

STATEMENTS_OF_OPERATIONS

STATEMENTS OF OPERATIONS (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Collaborative agreement	$54,229	$3,428	$3,428
Royalties	1,292
Total revenues	55,521	3,428	3,428
Operating expenses:
Research and development	57,412	56,748	73,680
General and administrative	28,639	23,878	19,987
Total operating expenses	86,051	80,626	93,667
Loss from operations	-30,530	-77,198	-90,239
Other income (expense):
Interest income	88	65	147
Interest expense	-7,083	-538	-2
Total other income (expense)	-6,995	-473	145
Net loss	($37,525)	($77,671)	($90,094)
Net loss per share-basic and diluted	($0.32)	($0.80)	($1.27)
Shares used to compute basic and diluted net loss per share	118,240	96,491	70,739

STATEMENTS_OF_COMPREHENSIVE_LO

STATEMENTS OF COMPREHENSIVE LOSS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net loss	($37,525)	($77,671)	($90,094)
Other comprehensive income (loss)
Unrealized gains (losses) on investment securities	-23	-18	17
Other comprehensive income (loss)	-23	-18	17
Comprehensive loss	($37,548)	($77,689)	($90,077)

STATEMENTS_OF_STOCKHOLDERS_EQU

STATEMENTS OF STOCKHOLDERS' EQUITY (USD $)	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
In Thousands, except Share data
Beginning balance at Dec. 31, 2011	$99,706	$61	$446,357	($2)	($346,710)
Beginning balance (in shares) at Dec. 31, 2011		61,285,000
Issuance of common stock and warrants, net of issuance costs (in shares)		11,000,000
Issuance of common stock and warrants, net of issuance costs	56,531	11	56,520
Net exercise of warrants (in shares)		11,131,000
Net exercise of warrants	11	11
Stock-based compensation expense	7,570		7,570
Exercise of common stock options (in shares)	997,608	998,000
Exercise of common stock options	1,728	1	1,727
Unrealized Gain (loss) on securities, available-for-sale	17			17
Net loss	-90,094				-90,094
Ending balance at Dec. 31, 2012	75,469	84	512,174	15	-436,804
Ending balance (in shares) at Dec. 31, 2012		84,414,000
Net exercise of warrants (in shares)		19,895,000
Net exercise of warrants	20	20
Stock-based compensation expense	11,567		11,567
Exercise of common stock options (in shares)	616,184	616,000
Exercise of common stock options	1,075	1	1,074
Issuance of common stock for Employee Stock Purchase Plan (in shares)		45,000
Issuance of common stock for Employee Stock Purchase Plan	242		242
Issuance of convertible senior notes, equity portion, net of issuance costs	31,178		31,178
Unrealized Gain (loss) on securities, available-for-sale	-18			-18
Net loss	-77,671				-77,671
Ending balance at Dec. 31, 2013	41,862	105	556,235	-3	-514,475
Ending balance (in shares) at Dec. 31, 2013		104,970,000
Net exercise of warrants (in shares)		17,295,000
Net exercise of warrants	17	17
Stock-based compensation expense	15,296		15,296
Exercise of common stock options (in shares)	1,111,552	1,112,000
Exercise of common stock options	2,286	1	2,285
Issuance of common stock for Employee Stock Purchase Plan (in shares)		84,000
Issuance of common stock for Employee Stock Purchase Plan	431		431
Unrealized Gain (loss) on securities, available-for-sale	-23			-23
Net loss	-37,525				-37,525
Ending balance at Dec. 31, 2014	$22,344	$123	$574,247	($26)	($552,000)
Ending balance (in shares) at Dec. 31, 2014		123,461,000

STATEMENTS_OF_CASH_FLOWS

STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net loss	($37,525)	($77,671)	($90,094)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of premium on investment securities, available-for-sale	751	815	500
Accretion of debt discount	3,877	313
Amortization of debt issuance costs	43	3
Depreciation	139	94	313
Loss on disposal of equipment			42
Stock-based compensation	15,296	11,567	7,570
Changes in operating assets and liabilities:
Accounts receivable	-2,494
Inventory	-1,198
Prepaid expenses and other current assets	-175	205	-365
Accounts payable and accrued expenses	2,107	-2,291	17,306
Other assets	112	-686
Deferred rent and lease incentives	124	262	-186
Deferred revenue	45,771	-3,428	-3,428
Net cash provided by (used) in operating activities	26,828	-70,817	-68,342
Investing activities
Purchases of investment securities, available-for-sale	-130,390	-85,647	-78,921
Maturities and sales of investment securities, available-for-sale	107,196	65,011	65,211
Purchases of property and equipment	-246	-640
Restricted cash			365
Net cash used in investing activities	-23,440	-21,276	-13,345
Financing activities
Proceeds from issuance of convertible notes, net		110,545
Proceeds from issuance of common stock and warrants	2,734	1,337	58,270
Net cash provided by financing activities	2,734	111,882	58,270
Increase (decrease) in cash and cash equivalents	6,122	19,789	-23,417
Cash and cash equivalents at beginning of period	98,121	78,332	101,749
Cash and cash equivalents at end of period	104,243	98,121	78,332
Supplemental Disclosure of Cash flow Information:
Interest paid	3,119
Unrealized gain (loss) on investment securities, available-for-sale	-23	-18	17
Supplemental Disclosure of Non-Cash Investing Information:
Purchases of equipment included in accounts payable	$120

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2014
Organization and Basis of Presentation	1. Organization and Basis of Presentation
	Orexigen Therapeutics, Inc. (the “Company”), a Delaware corporation, is a biopharmaceutical company focused on the development of pharmaceutical product candidates for the treatment of obesity. The Company was incorporated in September 2002 and commenced operations in 2003.
	The Company’s primary activities since incorporation have been organizational activities, including recruiting personnel, conducting research and development, including clinical trials, raising capital, and preparing for the marketing and commercialization of its sole product, Contrave, in the United States. Contrave was launched commercially in the United States by the Company’s partner, Takeda Pharmaceutical Company Limited (“Takeda”), in October 2014. The Company has experienced losses since its inception, and as of December 31, 2014, had an accumulated deficit of $552.0 million. The Company expects to continue to incur losses for at least the next several years. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure, and until that time, the Company may need to continue to raise additional equity or debt financing.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies
	Use of Estimates
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
	Cash and Cash Equivalents
	The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents.
	Investment Securities, Available-for-Sale
	The Company classifies all investment securities as available-for-sale, as the sale of such securities may be required prior to maturity to implement management strategies. These investment securities are carried at fair value, with unrealized gains and losses reported as accumulated other comprehensive income (loss) until realized. The cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion, as well as interest and dividends, are included in interest income. Realized gains and losses from the sale of available-for-sale securities, if any, are determined on a specific identification basis and are also included in interest income.
	Restricted Cash
	As of December 31, 2014, restricted cash represents a certificate of deposit pledged as collateral for a letter of credit issued by the Company in connection with the execution of an operating lease.
	Fair Value of Financial Instruments
	The carrying amount of cash and cash equivalents, accounts payable and accrued expenses are considered to be representative of their respective fair value because of the short-term nature of these items. Investment securities, available-for-sale, are carried at fair value.
	Concentration of Credit Risk
	Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and investment securities, available-for-sale. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. However, management believes the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which these deposits are held. Additionally, the Company has established guidelines regarding the diversification of its investments and their maturities, which are designed to maintain safety and liquidity.
	Concentration of Revenue and Accounts Receivable
	Takeda accounted for 100% of revenue for each of the years ended December 31, 2014, 2013 and 2012. Takeda also accounted for 100% of our accounts receivable as of December 31, 2014 and 2013.
	Property and Equipment
	Property and equipment is stated at cost and depreciated over the estimated useful lives of the assets (three to five years) using the straight-line method. Leasehold improvements are stated at cost and amortized over the shorter of their useful lives or the lease term.
	Impairment of Long-Lived Assets
	The Company will record impairment losses on long-lived assets used in operations when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. The Company has not recognized any impairment losses as of December 31, 2014.
	Research and Development Costs
	All research and development costs are charged to expense as incurred and consist principally of costs related to clinical trials, license fees and salaries and related benefits. Clinical trial costs are a significant component of research and development expenses. These costs are accrued based on estimates of work performed, and require estimates of total costs incurred based on patients enrolled, progress of clinical studies and other events. Clinical trial costs are subject to revision as the trials progress and revisions are charged to expense in the period in which they become known.
	Patent Costs
	All costs related to filing and pursuing patent applications are expensed as incurred as recoverability of such expenditures is uncertain.
	Inventory
	Inventories are stated at the lower of cost (using a first-in, first-out basis) or market. Inventory costs including raw materials and finished goods that may be associated with its products prior to regulatory approval are charged to research and development expense prior to such approval on a country-specific basis.
	Income Taxes
	Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities using enacted tax rates which will be in effect when the differences reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax asset will be realized.
	The Company follows the provisions of the Income Taxes Topic of the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification that defines a recognition threshold and measurement attributes for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. Under the Income Taxes Topic, the impact of an uncertain income tax position on the income tax return must be recognized at the largest amount that is more-likely-than-not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained.
	Revenue Recognition
	The Company has entered into agreements with Takeda which contain multiple elements, including nonrefundable upfront fees, payments associated with achieving specific development milestones and royalties based on specified percentages of net product sales, if any.
	Prior to the revised multiple element and milestone method of revenue recognition guidance adopted by the Company on January 1, 2011, nonrefundable, up-front license fees and milestone payments with standalone value that are not dependent on any future performance by the Company under the agreements were recognized as revenue upon the earlier of when payments were received or collection was assured, but were deferred if the Company had continuing performance obligations. If the Company had continuing involvement through contractual obligations under such agreements, such up-front fees were deferred and recognized over the period for which the Company continued to have a performance obligation. The collaboration agreement with Takeda has continuing obligations, and as a result the up-front fees were deferred upon receipt.
	Effective January 1, 2011, for multiple element agreements entered into or materially modified after December 31, 2010, the Company follows the provisions of Accounting Standards Update (“ASU”) No. 2009-13. In order to account for the multiple-element arrangements, the Company identifies the deliverables included within the agreement 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. A delivered item is considered a separate unit of accounting when the delivered item has value to the partner on a standalone basis based on the consideration of the relevant facts and circumstances for each arrangement. Factors considered in this determination include the research capabilities of the partner and the availability of research expertise in this field in the general marketplace. Arrangement consideration is allocated at the inception of the agreement to all identified units of accounting based on their relative selling price. The relative selling price for each deliverable is determined using vendor-specific objective evidence (“VSOE”) of selling price or third-party evidence of selling price if VSOE does not exist. If neither VSOE nor third-party evidence of selling price exists, we use our best estimate of the selling price for the deliverable. The amount of allocable arrangement consideration is limited to amounts that are fixed or determinable. The consideration received is allocated among the separate units of accounting, and the applicable revenue recognition criteria are applied to each of the separate units. Changes in the allocation of the sales price between delivered and undelivered elements can impact revenue recognition but do not change the total revenue recognized under any agreement. Upfront license fee payments are recognized upon delivery of the license if facts and circumstances dictate that the license has standalone value from the undelivered items, which generally include research and development services and the manufacture of drug products, the relative selling price allocation of the license is equal to or exceeds the upfront license fee, persuasive evidence of an arrangement exists, the Company’s price to the partner is fixed or determinable, and collectability is reasonably assured.
	Upfront license fee payments are deferred if facts and circumstances dictate that the license does not have standalone value. The determination of the length of the period over which to defer revenue is subject to judgment and estimation and can have a material impact on the amount of revenue recognized in a given period.
	The terms of the Company’s partnership agreements provide for milestone payments upon achievement of certain regulatory/development and sales-based events. Effective January 1, 2011, the Company adopted on a prospective basis the guidance under ASU No. 2010-17, “Revenue Recognition-Milestone Method”. Under the Milestone Method of accounting, the Company recognizes consideration that is contingent upon the achievement of a milestone in its entirety as revenue in the period in which the milestone is achieved only if the milestone is substantive in its entirety. A milestone is considered substantive when it meets all of the following three criteria: 1) The consideration is commensurate with either the entity’s performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity’s performance to achieve the milestone, 2) The consideration relates solely to past performance, and 3) The consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. A milestone is defined as an event (i) that can only be achieved based in whole or in part on either the entity’s performance or on the occurrence of a specific outcome resulting from the entity’s performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved and (iii) that would result in additional payments being due to the Company. Any milestone payments received prior to satisfying these revenue recognition criteria were recorded as deferred revenue in the accompanying consolidated financial statements.
	Royalties to be received based on sales of the Company’s licensed products by partners will be recognized as earned.
	Convertible Senior Notes
	In December 2013, the Company issued $115.0 million in aggregate principal amount of 2.75% convertible senior notes due 2020 (the “2020 Notes”). The 2020 Notes are accounted for in accordance with FASB ASC 470, formerly FSP APB 14-1, Accounting for Convertible Debt Instruments That May be Settled in Cash upon Conversion (Including Partial Cash Settlement). ASC Subtopic 470-20 requires the issuer of convertible debt that may be settled in shares or cash upon conversion at their option, such as the 2020 Notes, to account for the liability (debt) and equity (conversion option) components separately. The guidance requires the carrying amount of the liability component to be estimated by measuring the fair value of a similar liability that does not have an associated conversion feature. To measure the fair value of the liability component, the Company used an income approach, discounting the future contractual cash flows due under the 2020 Notes by a market interest rate. The market interest rate was determined to be 8.69%. Assumptions used in the estimate represent what market participants would use in pricing the liability component, including market interest rates, credit standing, and yield curves, all of which are defined as Level 2 observable inputs. The estimated implied interest rate was applied to the 2020 Notes, which resulted in a fair value of the liability component of $79.7 million upon issuance, calculated as the present value of implied future payments based on the $115.0 million aggregate principal amount. The $31.3 million difference between the cash proceeds of $111.0 million and the estimated fair value of the liability component was recorded in additional paid-in capital as the 2020 Notes. The liability component will be accreted to redemption value over the term of the 2020 Notes.
	Stock-Based Compensation
	The Company measures and recognizes compensation expense for all stock-based payment awards made to employees, non-employee directors and consultants, including stock options and employee stock purchases related to the Company’s 2013 Employee Stock Purchase Plan, based on estimated fair values. Compensation costs related to all equity instruments granted are recognized at the grant-date fair value of the awards. Additionally, the Company includes an estimate of the number of awards that will be forfeited in calculating compensation costs, which is recognized over the requisite service period of the awards on a straight-line basis. No related tax benefits of the share-based compensation costs have been recognized since the Company’s inception.
	The fair value of each option award was estimated on the date of grant using the Black-Scholes option valuation model. The following weighted-average assumptions were utilized for the calculations during each period:
		Years Ended December 31,
		2014			2013			2012
	Expected life (in years)		5.6			6			6
	Expected volatility		107.3	%		92.7	%		87.5	%
	Risk-free interest rate		1.8	%		1.2	%		1.1	%
	Expected dividend yield		0	%		0	%		0	%
	Per share grant-date fair value	$	5.01		$	4.35		$	2.26
	The weighted average expected life of an award is based on historical forfeiture experience, exercise activity, and on the terms and conditions of the stock awards. The expected volatility is based on the historical volatility of the Company’s common stock over the most recent period commensurate with the estimated expected term of the stock awards. The risk-free interest rate assumption was based on the United States Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued. The assumed dividend yield was based on the Company’s expectation of not paying dividends in the foreseeable future.
	Total stock-based compensation expense recognized during the years ended December 31, 2014, 2013 and 2012 was comprised of the following (in thousands):
		Years Ended December 31,
		2014			2013			2012
	General and administrative	$	10,842		$	8,162		$	5,755
	Research and development		4,454			3,405			1,815
		$	15,296		$	11,567		$	7,570
	At December 31, 2014, total unrecognized estimated share-based compensation expense related to non-vested stock options granted prior to that date was $26.7 million, which is expected to be recognized over a weighted-average period of 1.8 years.
	Comprehensive Loss
	The Company records all components of comprehensive income, including net income, in the financial statements in the period in which they are recognized. Comprehensive loss consists of net loss and certain changes in stockholders’ equity that are excluded from net loss. Comprehensive loss for each of the years ended December 31, 2014, 2013 and 2012 has been reflected in the Statements of Comprehensive Loss. Accumulated other comprehensive income (loss), which is included in stockholders’ equity, represents unrealized gains and losses on investment securities, available-for-sale.
	Comprehensive loss includes net loss and unrealized gains and losses on investments. The Company discloses the accumulated balance of other comprehensive loss as a separate component of stockholder’s equity.
	Net Loss Per Share
	The Company computes basic loss per share by dividing the net loss available to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss assumes the conversion, exercise or issuance of all potential common stock equivalents, unless the effect of inclusion would be anti-dilutive. For purposes of this calculation, common stock equivalents include the Company’s stock options and Employee Stock Purchase Plan (ESPP), warrants and the shares to be issued upon the conversion of the convertible senior notes. No shares related to the assumed conversion of the convertible senior notes were included in the diluted net loss calculation for the years ended December 31, 2014, 2013 and 2012 because the inclusion of such shares would have had an anti-dilutive effect. The shares to be issued upon exercise of certain outstanding stock options and common stock warrants were excluded from the diluted net loss calculation for all periods presented because such shares are anti-dilutive.
	(In thousands, except per share amounts)	Years Ended December 31,
		2014			2013			2012
	Historical
	Numerator:
Net loss	$	(37,525	)	$	(77,671	)	$	(90,094	)
Denominator:
Weighted average common shares outstanding		118,240			96,491			70,739
Denominator for basic and diluted net loss per share		118,240			96,491			70,739
Net loss per share—basic and diluted	$	(0.32	)	$	(0.80	)	$	(1.27	)
Historical outstanding anti-dilutive securities not included in the diluted net loss per share calculation include the following (in thousands):
	As of December 31,
	2014			2013			2012
Shares underlying convertible senior notes		14,042			14,042			—
Common stock warrants outstanding		572			17,870			37,768
Common stock options outstanding		17,959			16,902			13,839
		32,573			48,814			51,607
Recently Issued Accounting Standards
In May 2014, the FASB issued new accounting guidance related to revenue recognition. This new standard will replace all current generally accepted accounting principles guidance on this topic and eliminate all industry-specific guidance. The new revenue recognition standard provides a unified model to determine when and how revenue is recognized. The core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration for which the entity expects to be entitled in exchange for those goods or services. This guidance will be effective for fiscal years beginning after December 16, 2016, including interim periods within that reporting period, and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. Early adoption is prohibited. The Company is evaluating the impact of adopting this new accounting standard on its financial statements and related disclosures.

Investment_Securities_Availabl

Investment Securities, Available-for-Sale	12 Months Ended
	Dec. 31, 2014
Investment Securities, Available-for-Sale	3. Investment Securities, Available-for-Sale
	The Company invests its excess cash in investment securities, principally debt instruments of financial institutions, corporations with investment grade credit ratings and government agencies. Regardless of maturity date, the Company intends to use all available-for-sale securities in current operations; therefore, these assets have been classified as short-term. A summary of the estimated fair value of investment securities, available-for-sale, is as follows at December 31, 2014 and December 31, 2013 (in thousands):
	December 31, 2014	Maturity in Years	Amortized		Unrealized					Fair
			Cost		Gains		Losses			Value
	U.S. government agency securities	Less than 1	$	87,895	$	4	$	(27	)	$	87,872
	Corporate debt securities	Less than 1		5,074		—		(1	)		5,073
	U.S. government agency securities	More than 1		8,351		—		(2	)		8,349
	Total investment securities		$	101,320	$	4	$	(30	)	$	101,294
	December 31, 2013	Maturity in Years	Amortized		Unrealized					Fair
			Cost		Gains		Losses			Value
	U.S. government agency securities	Less than 1	$	77,877	$	4	$	(7	)	$	77,874
	U.S. Treasury securities	Less than 1		1,001		—		—			1,001
	Total investment securities		$	78,878	$	4	$	(7	)	$	78,875
	Gross realized gains and losses on available-for-sale securities were immaterial during the years ended December 31, 2014, 2013 and 2012.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Measurements	4. Fair Value Measurements
	The following table presents information about the Company’s financial assets measured at fair value on a recurring basis as of December 31, 2014, and indicates the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. The Company classifies money market funds as Level 1 assets. Fair values determined by Level 2 inputs utilize inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, and inputs other than quoted prices that are observable for the asset or liability, such as interest rates and yield curves that are observable at commonly quoted intervals. The Company classifies commercial paper holdings, U.S. Treasury securities, U.S. government agency securities and asset-backed security holdings as Level 2 assets. Level 3 inputs are unobservable inputs for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. The Company does not hold any Level 3 assets. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy within which the fair value measurement in its entirety falls has been determined based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.
	Assets that have recurring measurements are shown below (in thousands):
				Fair Value Measurement at Reporting Date Using
	Description	Balance as of		Quoted Prices in		Significant Other		Significant
		December 31,		Active Markets		Observable		Unobservable
		2014		for Identical		Inputs (Level 2)		Inputs (Level 3)
				Assets (Level 1)
	Financial instruments owned:
	Money market funds	$	97,966	$	97,966	$	—	$	—
	U.S. government agency securities		100,720		—		100,720		—
	Corporate debt securities		5,073		—		5,073		—
	Total financial instruments owned	$	203,759	$	97,966	$	105,793	$	—
				Fair Value Measurement at Reporting Date Using
	Description	Balance as of		Quoted Prices in		Significant Other		Significant
		December 31,		Active Markets		Observable		Unobservable
		2013		for Identical		Inputs (Level 2)		Inputs (Level 3)
				Assets (Level 1)
	Financial instruments owned:
	Money market funds	$	96,910	$	96,910	$	—	$	—
	U.S. Treasury securities		1,001		—		1,001		—
	U.S. government agency securities		77,874		—		77,874		—
	Total financial instruments owned	$	175,785	$	96,910	$	78,875	$	—

Inventory

Inventory	12 Months Ended
	Dec. 31, 2014
Inventory	5. Inventory
	Upon receiving U.S. Food and Drug Administration (“FDA”) approval of Contrave in September 2014, the Company began to capitalize certain inventory costs for Contrave, which were recorded as research and development expenses prior to such approval.
	Inventory consists of the following (in thousands):
		December 31,
		2014		2013
	Raw materials	$	755	$	—
	Work in process		58		—
	Finished goods		385		—
		$	1,198	$	—

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2014
Property and Equipment	6. Property and Equipment
	Property and equipment consists of the following (in thousands):
			December 31,
		Useful Life in Years	2014			2013
	Furniture and fixtures	5	$	1,079		$	1,079
	Computer equipment and software	3 to 5		521			422
	Leasehold improvements	5		557			557
	Manufacturing equipment	5		640			—
	Asset under construction			120			518
				2,917			2,576
	Accumulated depreciation			(2,060	)		(1,946	)
	Property and equipment, net		$	857		$	630
	Depreciation expense was $139,000, $94,000 and $313,000 for each of the years ended December 31, 2014, 2013 and 2012, respectively.

Accrued_Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2014
Accrued Expenses	7. Accrued Expenses
	Accrued expenses consist of the following (in thousands):
		December 31,
		2014		2013
	Accrued compensation related expenses	$	4,666	$	4,774
	Accrued research and development expenses		1,187		1,273
	Accrued interest on convertible notes		264		220
	Accrued legal and professional expenses		156		355
	Other accrued expenses		279		129
		$	6,552	$	6,751

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies	8. Commitments and Contingencies
	2.75% Convertible Senior Notes due 2020
	In December 2013, the Company issued $115.0 million in aggregate principal amount of 2.75% convertible senior notes due 2020 (“2020 Notes”) in an offering to qualified institutional buyers conducted in accordance with Rule 144A under the Securities Act of 1933, as amended. Debt issuance costs of approximately $488,000 were primarily comprised of legal, accounting and other professional fees, the majority of which were recorded in other noncurrent assets and are being amortized to interest expense over the seven-year term of the 2020 Notes.
	Upon conversion, the 2020 Notes will be settled in shares of the Company’s common stock (together with cash in lieu of any fractional shares). However, if the Company receives stockholder approval in accordance with the Nasdaq Listing Standards, the Company will settle conversions of the 2020 Notes through payment or delivery, as the case may be, of cash, shares of the Company’s common stock or a combination thereof, at the Company’s election. The conversion rate for the Notes will initially be 122.1225 shares per $1,000 principal amount, which is equivalent to an initial conversion price of approximately $8.19 per share of common stock, and is subject to adjustment under the terms of the Notes.
	The 2020 Notes will mature on December 1, 2020, unless earlier repurchased or converted in accordance with their terms prior to such date. Prior to the close of business on the business day immediately preceding September 1, 2020, holders may convert all or a portion of their 2020 Notes only under the following circumstances: (1) during any fiscal quarter commencing after March 31, 2014, if, for at least 20 trading days (whether or not consecutive) during the 30 consecutive trading day period ending on the last trading day of the immediately preceding fiscal quarter, the last reported sale price of the Company’s common stock on such trading day is greater than or equal to 130% of the applicable conversion price on such trading day; (2) during the five consecutive business day period immediately following any ten consecutive trading day period (the “measurement period”) in which, for each trading day of that measurement period, the trading price per $1,000 principal amount of notes for such trading day was less than 98% of the product of the last reported sale price of the Company’s common stock on such trading day and the applicable conversion rate on such trading day, or (3) upon the occurrence of specified corporate transactions. On and after September 1, 2020 until the close of business on the business day immediately preceding the maturity date, holders may convert all or a portion of their 2020 Notes at any time, regardless of the foregoing circumstances. Holders of the Notes will have the right to require the Company to repurchase all or some of their Notes at 100% of their principal amount, plus any accrued and unpaid interest, upon the occurrence of certain events.
	The Company pays 2.75% interest per annum on the principal amount of the 2020 Notes semi-annually in arrears in cash on June 1 and December 1 of each year, beginning on June 1, 2014. If a designated event, as defined in the indenture for the 2020 Notes, including, but not limited to, a change in control, certain mergers or liquidation, occurs prior to the maturity date, subject to certain limitations, holders of the Notes may require the Company to repurchase all or a portion of their 2020 Notes for cash at a repurchase price equal to 100% of the principal amount of the 2020 Notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the repurchase date.
	The Company accounts separately for the liability and equity components of the 2020 Notes in accordance with authoritative guidance for convertible debt instruments that may be settled in cash upon conversion. The guidance requires the carrying amount of the liability component to be estimated by measuring the fair value of a similar liability that does not have an associated conversion feature. Because the Company has no outstanding non-convertible public debt, the Company determined that senior, unsecured corporate bonds traded on the market represent a similar liability to the 2020 Notes without the conversion option. The Company estimated the implied interest rate of its 2020 Notes to be 8.69%, assuming no conversion option. Assumptions used in the estimate represent what market participants would use in pricing the liability component, including market interest rates, credit standing, and yield curves, all of which are defined as Level 2 observable inputs. The estimated implied interest rate was applied to the 2020 Notes, which resulted in a fair value of the liability component of $79.7 million upon issuance, calculated as the present value of implied future payments based on the $115.0 million in aggregate principal amount. The $31.3 million difference between the cash proceeds of $111.0 million and the estimated fair value of the liability component was recorded in additional paid-in capital as the 2020 Notes were not considered redeemable.
	A summary of the liability and equity components of the 2020 Notes is as follows at December 31, 2014 and December 31, 2013 (in thousands):
		December 31,
		2014			2013
	Principal amount of senior convertible notes outstanding	$	115,000		$	115,000
	Unamortized discount of liability component		(31,092	)		(34,969	)
	Long term convertible debt	$	83,908		$	80,031
	Carrying value of equity component, net of issuance costs	$	31,178		$	31,178
	Remaining amortization period of discount on the liability component		6 years			7 years
	Operating Leases
	In December 2007, the Company entered into an operating lease agreement for office facilities (corporate headquarters) in San Diego, California. The term of the lease began in April 2008 and was for an initial term of 64 months. In February 2013, the Company entered into an amendment to extend its lease to September 2017. The monthly rental payments are adjusted on an annual basis. As security for the lease, the landlord required a letter of credit, which is collateralized by a certificate of deposit of $177,000, which is included in restricted cash in the accompanying balance sheet at December 31, 2014. Rent expense is being recorded on a straight-line basis over the life of the lease.
	In September 2008, the Company amended the lease to expand the office space at this location for a term of 52 months. In March 2012, the Company entered into a Partial Lease Termination Agreement with its landlord pursuant to which the Company decreased the total leased space at its corporate headquarters. The Agreement provided for, among other things, a one-time payment of $190,849 by the Company to the landlord and termination of the Company’s payment obligations with respect to the terminated premises.
	Future minimum payments under the operating leases as of December 31, 2014 are as follows (in thousands):
	Years Ending December 31,
	2015	$	1,053
	2016		1,085
	2017		742
	2018		—
	2019		—
		$	2,880
	Total rent expense for each of the years ended December 31, 2014, 2013 and 2012 was approximately $911,000, $1.1 million and $1.4 million, respectively.
	Technology and License Agreements
	Takeda Pharmaceutical Company Limited
	In September 2010, the Company entered into a collaboration agreement with Takeda to develop and commercialize Contrave in the United States, Canada and Mexico. Effective in September 2013, the Company and Takeda entered into an amendment to the collaboration agreement pursuant to which Takeda assumed from the Company the responsibility to package Contrave for commercial sale in the United States, Canada and Mexico. Under the terms of the collaboration agreement, the Company received a nonrefundable upfront cash payment of $50.0 million from Takeda and is eligible to receive additional payments of over $1.0 billion upon achieving certain anniversary, regulatory/development and sales-based milestones, including $100.0 million that can be achieved between the execution of the collaboration agreement and the first commercial sale of Contrave in the United States. Of the remaining eligible payments of over $900 million, $45 million is related to anniversary payments of equal amounts over a three year period ending on the third anniversary of the first commercial launch of Contrave, and the remaining payments are primarily related to payments to be made upon the achievement of sales-based milestones of Contrave. The Company is also eligible to receive tiered royalty payments ranging from a minimum of 20% to a maximum of 35%, subject to customary reductions, on increasing levels of net sales in the United States, Canada and Mexico. In accordance with the Company’s continuing performance obligation of the collaboration, the upfront payment of $50.0 million is being deferred and recognized over 14.5 years, the estimated term of the agreement. In addition to the upfront payment, the Company earned milestones of $30.0 million from Takeda for the FDA approval of Contrave and for delivery of launch supplies to Takeda in 2014. Also in October 2014, the Company earned and was paid a $70.0 million milestone from Takeda for the shipment of Contrave to pharmacy wholesalers in preparation for the commercial launch. This milestone payment was determined to not meet the definition of a substantive milestone. As a result, the Company recognized $20.8 million in 2014 with $49.2 million deferred which will be recognized over the remaining estimated life of the agreement. Additionally, the Company recognized $1.3 million in royalties earned for the sale of Contrave by Takeda in 2014.
	For the years ended December 31, 2014, 2013 and 2012, the Company recognized revenues under this agreement of $55.5 million, $3.4 million and $3.4 million, respectively. At December 31, 2014 and 2013, deferred revenue under this agreement totaled $84.3 million and $38.6 million, respectively. Also the Company recorded receivables at December 31, 2014 and 2013 for approximately $2.6 million and $77,000, respectively, for reimbursement by Takeda for royalty revenue earned on the sales of Contrave by Takeda and certain manufacturing and patent costs permitted under the collaboration agreement prior to FDA approval which were accounted for as a reduction of the expenses reimbursed. Total reimbursements of manufacturing expenses from Takeda was $7.6 million and $0 in 2014 and 2013, respectively.
	The Company has assessed milestones under the revised authoritative guidance for research and development milestones and determined that two regulatory/development milestone payments, $20.0 million due to the Company upon regulatory approval in the United States and $10.0 million due to the Company upon the delivery of launch supplies to Takeda, meet the definition of a milestone as: (1) they are events that can only be achieved in part on the Company’s performance or upon the occurrence of a specific outcome resulting in the Company’s performance, (2) there was substantive uncertainty at the date the agreement was entered into that the event will be achieved, and (3) they result in additional payments being due to the Company. These milestones were achieved during the three months ended September 30, 2014. The third regulatory/development milestone payment, $70.0 million due to the Company upon the first commercial sale in the United States, does not meet the definition of a milestone as Takeda is responsible for the commercialization of Contrave. Sales-based milestone payments currently do not meet these criteria and will not be classified as milestones as their achievement is solely based on the performance of Takeda. The Company has determined that the anniversary milestones do not meet the definition of a milestone as these payments are contingent solely upon the passage of time. The milestone payments related to the first commercial sale and anniversary payments will be included with the upfront payment as additional consideration paid under the agreement. The Company will record revenue for the proportion of the payment that has been earned from the inception of the agreement to the date the payment is earned. The remainder will be recorded over the remainder of the term of the agreement. The sales-based milestone payments and royalties will be recorded when earned.
	In September 2014, the Company and Takeda entered into a non-binding term sheet to address certain amendments and revisions to the collaboration agreement. Discussions between the Company and Takeda are ongoing and to date no definitive revised collaboration agreement has been executed by the parties.
	In September 2014, the Company and Takeda entered into a manufacturing services agreement in accordance with the collaboration agreement. Pursuant to the manufacturing services agreement, among other things, the Company will supply to Takeda, and Takeda will, subject to certain exceptions as set forth in the collaboration and manufacturing services agreements, exclusively purchase from the Company, at our cost, all of Takeda’s requirements of Contrave for commercialization in the United States, Canada and Mexico during the term of the collaboration agreement. At any time during the term of the collaboration agreement, Takeda may elect, subject to certain terms and conditions, to transfer and assume the right and responsibility to manufacture Contrave in the United States, Canada and Mexico. The Company has evaluated the terms of the manufacturing services agreement and concluded that it is not the principal in the transaction and is acting as an agent. As a result, the Company will record payments for purchases of Contrave by Takeda pursuant to this agreement on a net basis such that no revenue or costs is expected to be recognized in the statement of operations. Cost of inventory will be capitalized until such time that product is received by Takeda. All material costs of product sold to Takeda post FDA approval was previously expensed as research and development.
	In October 2014, the Company transferred the responsibility for conducting the Light Study to Takeda pursuant to the terms of the collaboration agreement, as amended. At December 31, 2014, the Company had a payable to Takeda of $6.5 million related to the clinical study.
	Oregon Health & Science University
	In June 2003, the Company entered into a license agreement with Oregon Health & Science University (“OHSU”), whereby the Company acquired an assignment of any rights OHSU may have to a U.S. provisional patent application that the Company filed, which formed the basis for the Company’s subsequently issued patents. This license agreement was amended in November 2003, December 2006 and December 2007. As consideration for this license agreement, the Company paid an upfront fee of $65,000 and issued 76,315 shares of the Company’s common stock to OHSU. The Company is also obligated to pay a royalty to OHSU on net sales for Contrave and any other products covered by the assigned patent rights. At December 31, 2014, the Company recorded a royalty payable of $65,000 under this agreement. The Company is also responsible for all prosecution and maintenance (including all costs associated with the enforcement) of any patent applications, that stem from these assigned rights, and for any patents that have or may issue with respect thereto.
	OHSU has also licensed to the Company, on an exclusive basis, the issued patent underlying the in vitro model that the Company has used for screening combination therapies for impact on neuronal activity. With respect to these rights, the Company was required to make a payment of $20,000 upon receipt of a pair of mice and is required to pay an additional $20,000 upon receipt of any additional pair of mice. OHSU is solely responsible for the prosecution, maintenance and enforcement (including all costs associated therewith) of this patent; however the Company is required to pay 100% of expenses incurred by OHSU in the maintenance and prosecution of this patent. As of December 31, 2014, the Company has paid a total of approximately $118,000 in connection with the maintenance and prosecution of this patent. In addition, OHSU has the right to not file any patent application or to abandon any patent or patent application included in the patent rights, in which case it must provide the Company 60 days’ prior written notice and, in response, the Company may elect at its sole cost to pursue these actions. The Company’s rights to this patent extend through the expiration of the patent, which is expected to occur in 2024.
	Duke University
	In March 2004, the Company entered into a patent license agreement (the “Duke Agreement”) with Duke University (“Duke”) whereby the Company acquired, among other things, an exclusive worldwide license to a U.S. patent. In February 2015, the Company terminated the license agreement with Duke. The Company does not expect to pay Duke any royalties on Contrave.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity	9. Stockholders’ Equity
	Common Stock and Common Stock Warrants
	In December 2011, the Company completed a public offering of 5,646,173 units. Each unit consists of one share of common stock and a warrant to purchase ten shares of common stock, at a price to the public of $1.45 per share of common stock and $1.449 per warrant to purchase each share of common stock, which together comprise the purchase price of $15.94 per unit. Net cash proceeds from the public offering were $86.9 million, after deducting underwriting discounts and commissions and offering expenses. The warrants issued in the transaction have an exercise price equal to $0.001 per share. Each warrant is exercisable in whole or in part for a period of 10 years commencing on December 22, 2011. A holder of a warrant will not have the right to exercise any portion of the warrant if such holder (together with its affiliates) would beneficially own in excess of 9.99% of the number of shares of the Company’s common stock outstanding immediately after giving effect to the exercise of such warrant. These warrants may only be exercised pursuant to a cashless net exercise, whereby the exercise price of the warrants is satisfied through the reduction in shares issued upon exercise equal in value to the exercise price. There are no provisions in the warrant agreement which would require the Company to settle the warrants through the distribution of cash. The initial warrants provided for the purchase of up to 56,461,730 shares. A total of 17,294,521, 19,895,061 and 11,130,548 shares were issued upon warrant exercises in 2014, 2013 and 2012, respectively. Warrants to purchase an aggregate of up to 572,040, 17,869,618 and 37,767,900 shares were outstanding as of December 31, 2014, 2013 and 2012, respectively.
	In October 2012, the Company completed a public offering of 11,000,000 shares of its common stock at a public offering price of $5.50 per share. Net cash proceeds from the public offering were approximately $56.5 million, after deducting underwriting discounts and commissions and offering expenses payable by the Company.
	Stock Options
	During 2004, the Company adopted the 2004 Stock Plan (the “2004 Plan”) under which, as amended, 3,159,275 shares of common stock are reserved for issuance to employees, directors and consultants of the Company. The 2004 Plan provides for the grant of incentive stock options, non-statutory stock options and rights to purchase restricted stock to eligible recipients. Recipients of incentive stock options shall be eligible to purchase shares of the Company’s common stock at an exercise price equal to no less than the estimated fair market value of such stock on the date of grant. The maximum term of options granted under the 2004 Plan is ten years. The options generally vest over four years, and some are immediately exercisable. At December 31, 2014, no stock options are outstanding under the 2004 Plan.
	In February 2007, the Company’s stockholders approved the 2007 Equity Incentive Award Plan (the “2007 Plan”), which became effective in April 2007, under which 3,525,000 shares of common stock were initially reserved for future issuance to employees, directors and consultants of the Company. Effective January 1, 2009, 2010 and 2011, the Company’s Board of Directors increased the shares available for issuance under the 2007 Plan by 1,721,666, 2,000,000 and 2,000,000 shares, respectively, in accordance with an “evergreen” provision. The 2007 Plan provides for the issuance of stock options, stock appreciation rights, restricted stock units, performance stock units, and other stock-based awards. The 2007 Plan has an initial term of ten years. As of the effectiveness of the 2007 Plan, no additional shares will be granted under the 2004 Plan. The 2007 Plan was amended in October 2009 and February 2010 to provide for the reservation of 500,000 and 2,000,000 shares, respectively, of the Company’s common stock to be used exclusively for the grant of awards to individuals not previously an employee or non-employee director of the Company (or following a bona fide period of non-employment with the Company), as an inducement material to the individual’s entering into employment with the Company within the meaning of Rule 5635(c)(4) of the NASDAQ Listing Rules. In June 2011, the 2007 Plan was amended to, among other things, add an additional 10,000,000 shares to the number of shares of common stock authorized for issuance under the 2007 Plan, increase the number of shares to be added to the 2007 Plan automatically each January 1, starting with January 1, 2012, to the least of (i) 15% of the Company’s outstanding common stock on the applicable January 1, (ii) 6,000,000 shares of common stock and (iii) a lesser number of shares of the Company’s common stock determined by the Company’s board of directors, and increase the limitation on the number of shares that may be granted pursuant to the exercise of incentive stock option to 40,000,000 shares. At December 31, 2014, options to purchase 17,958,969 shares have been granted and are outstanding under the 2007 Plan.
	In June 2011, to provide incentive to the employees of the Company to continue their employment, the Company announced an option exchange program. Under the exchange program, eligible optionholders had an opportunity to exchange eligible stock options for a new stock option issued under the Company’s 2007 equity incentive award plan. The exercise price of the new option was $1.66 per share, which was the closing price of the Company’s common stock as reported by the Nasdaq Global Market on the first business day after the expiration date of the exchange offer. New options granted to employees vest over four years, with the shares vesting in equal monthly installments over 48 months. On July 22, 2011, the eligible optionholders exchanged options exercisable for an aggregate of 7,407,634 shares of common stock in the program. On July 25, 2011, the Company issued new stock options exercisable for an aggregate of 7,407,634 shares of common stock with an exercise price of $1.66 per share. As a result of the option exchange program, the Company is recognizing additional stock-based compensation expense of $2.7 million over the four year vesting period of the new stock options.
	In March 2011, to provide incentive to the employees of the Company to continue their employment while its management and Board worked to update the Company’s corporate strategy, the Compensation Committee of the Company’s Board of Directors approved an amendment to certain outstanding option grants to provide for a one-time repricing of the exercise price of such options to purchase shares of the Company’s common stock held by employees (the “Repricing”). The Repricing affected an aggregate of 1,443,150 shares of the Company’s common stock subject to outstanding option grants (the “Affected Grants”). An aggregate of 492,357 shares subject to the Affected Grants had an original exercise price of $5.89 (the “September 2010 Grants”) and the remaining 950,793 shares had an exercise price of $9.31 (the “January 2011 Grants”). The vesting commencement date for both the September 2010 Grants and the January 2011 Grants was January 18, 2011. The Compensation Committee chose to amend the September 2010 Grants and the January 2011 Grants because they believed that the amendment of these grants would achieve the desired retentive affect for the Company’s employees given the circumstances around the Company’s recent corporate realignment. The exercise price of all Affected Grants was amended in the Repricing to $2.94, the closing price of the Company’s common stock on March 2, 2011. As a result of the Repricing, the Company is recognizing additional stock-based compensation expense of $819,000 over the four year vesting period of the Affected Grants.
	The following table summarizes stock option activity for the 2004 and 2007 Plans:
		Number of			Weighted Average
		Options			Exercise Price
	Outstanding at December 31, 2011		10,586,379		$	1.92
	Granted		4,268,125			3.1
	Exercised		(997,608	)		1.74
	Forfeited		(18,002	)		3.44
	Outstanding at December 31, 2012		13,838,894		$	2.29
	Granted		4,069,507			5.77
	Exercised		(616,184	)		1.78
	Forfeited/Cancelled		(390,070	)		4.38
	Outstanding at December 31, 2013		16,902,147		$	3.1
	Granted		3,194,512			6.22
	Exercised		(1,111,552	)		2.07
	Forfeited		(1,026,138	)		5.35
	Outstanding at December 31, 2014		17,958,969		$	3.59
	The following table summarizes information about stock options outstanding under the 2007 Plan at December 31, 2014:
		Options Outstanding							Options Exercisable
	Range of	Number of			Weighted		Weighted		Number of		Weighted
	Exercise Prices	Options			Average		Average		Options		Average
					Remaining		Exercise Price				Exercise Price
					Contractual Life
					(In Years)
	$1.61 - $1.66		5,261,871			6.6	$	1.66		4,210,658	$	1.66
	$1.70 - $2.58		4,559,386			6.7	$	2.21		3,585,808	$	2.18
	$3.12 - $5.69		4,537,814			7.1	$	5.08		2,746,256	$	4.84
	$5.73 - $8.18		3,599,898			8.6	$	6.29		1,296,225	$	6.38
	$1.61 - $8.18		17,958,969			7.2	$	3.59		11,838,947	$	3.07
	As of December 31, 2014, the aggregate intrinsic value of options outstanding and exercisable was approximately $45.3 million and $35.8 million, respectively. The aggregate intrinsic value of options exercised was $ 3.6 million, $3.1 million and $4.6 million during the year ended December 31, 2014, 2013 and 2012, respectively. At December 31, 2014, the weighted average remaining contractual term for options exercisable was 6.7 years.
	Employee Stock Purchase Plan
	In June 2013, the Company’s stockholders approved the Company’s ESPP, which permits the Company’s eligible employees to purchase shares of common stock, at semi-annual intervals, through periodic payroll deductions. Payroll deductions may not exceed 15% of the participant’s cash compensation subject to certain limitations, and the purchase price will not be less than 85% of the lower of the fair market value of the stock at either the beginning of the applicable “Offering Period” or the Purchase Date. Each Offering Period is 24 months, with new Offering Periods commencing every six months on the dates of June 1 and December 1 of each year. Each Offering Period consists of four (4) six month purchase periods (each a “Purchase Period”) during which payroll deductions of the participants are accumulated under the ESPP. The last business day of each Purchase Period is referred to as the “Purchase Date.” Purchase Dates are every six months on the last business day of May and November.
	The assumptions used for the years ended December 31, 2014 and 2013 and the resulting estimates of weighted-average fair value per share for stock purchased under the ESPP during 2014 and 2013 are as follows:
		Years Ended
		December 31,
		2014		2013
	Expected term (in years)	0.49 – 2.00		0.45 – 1.95
	Expected volatility	49.1 – 72.9%		46.6 – 72.8%
	Risk-free interest rate	0.06 – 0.49%		0.07 – 0.26%
	Expected dividend yield	0.00%		0.00%
	At December 31, 2014, total unrecognized estimated stock-based compensation expense related to the ESPP was approximately $326,000, which is expected to be recognized over a weighted-average period of approximately 9 months. A total of 6,000,000 shares of the Company’s common stock have been reserved for issuance under the ESPP plan. 84,325 and 45,285 shares were issued under the ESPP during the years ended December 31, 2014 and 2013, respectively.
	Common stock reserved for future issuance consists of the following at December 31, 2014:
	Common stock warrants		572,040
	Available for future issuance under ESPP		5,870,390
	Stock options issued and outstanding		17,958,969
	Authorized for future option grants		7,769,668
			32,171,067

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Taxes	10. Income Taxes
	The Company did not recognize federal or state income tax expense or benefit for the years ended December 31, 2012, 2013, or 2014.
	A reconciliation of income taxes to the amount computed by applying the statutory federal income tax rate to the net loss is summarized as follows:
		December 31,
	(In thousands)	2014			2013			2012
	Income tax expense (benefit) at statutory rates	$	(13,133	)	$	(27,184	)	$	(31,532	)
	State income tax, net of federal benefit		(422	)		(4,242	)		(5,073	)
	Permanent items		2,157			804			379
	Uncertain tax positions		843			2,629			69
	Research and development credits		(2,041	)		(5,492	)		(344	)
	Stock-based compensation		751			760			447
	Change in rate		(2,624	)		—			(20	)
	Change in valuation allowance		14,469			32,725			36,074
	Income tax expense (benefit)	$	—		$	—		$	—
	Significant components of the Company’s deferred tax assets as of December 31, 2014 and 2013 are shown below. A valuation allowance has been recognized to offset the net deferred tax assets as realization of such deferred tax assets has not met the more likely than not threshold.
		December 31,
	(In thousands)	2014			2013
	Deferred tax assets:
	Net operating loss carryforwards	$	55,035		$	63,794
	Research and development credits		5,988			4,752
	Capitalized research and development expenditures		2,439			2,859
	Deferred revenue		34,205			15,716
	Stock-based compensation		10,911			8,919
	Other, net		2,409			1,884
	Total deferred tax assets		110,987			97,924
	Valuation allowance for deferred tax assets		(99,807	)		(85,330	)
	Deferred tax assets, net of valuation allowance		11,180			12,594
	Deferred tax liabilities:
	Convertible debt		(11,180	)		(12,594	)
	Total deferred tax liabilities		(11,180	)		(12,594	)
		$	—		$	—
	At December 31, 2014, the Company has federal and state net operating loss carryforwards of approximately $398.1 million and $390.9 million, respectively, not considering the IRC Section 382 annual limitation discussed below. The federal loss carryforwards begin to expire in 2024, unless previously utilized. At December 31, 2014, the Company has federal and state research and development tax credits of $18.5 million and $5.5 million, respectively. The federal research and development tax credits begin to expire in 2024 unless previously utilized. The state research and development tax credits carry forward indefinitely.
	The California net operating loss carry forwards are scheduled to expire as follows (in thousands):
	Year	Amount
	2015	$	4,557
	2016		20,936
	2017		49,842
	2018		3,841
	2028 and beyond		311,309
	Approximately $11.4 million of the net operating loss carryforwards relate to excess tax deductions for stock compensation, the income tax benefit of which will be recorded as additional paid-in-capital if and when realized.
	Additionally, the utilization of the net operating loss and research and development tax credit carryforwards is subject to an annual limitation under Section 382 and 383 of the Internal Revenue Code of 1986, and similar state tax provisions due to ownership change limitations that have occurred previously or that could occur in the future. These ownership changes limit the amount of the net operating loss and research and development tax credit carryforwards and other deferred tax assets that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Section 382 and 383, results from transactions increasing ownership of certain stockholders or public groups in the stock of the corporation by more than 50 percentage points over a three-year period. The Company has completed an ownership change analysis in accordance with Section 382 from inception through December 31, 2014. As a result of the analysis, it was determined that the Company experienced several ownership changes during this period with the last one occurring in December 2014. The analysis to determine the limitation of NOLs and credits as a result of the ownership changes has not been finalized. Based on our preliminary analysis of the limitation of our net operating losses and federal credits, the Company has removed deferred tax assets for net operating losses of $254.1 million and $231.1 million for federal and state, respectively, and federal research and development credits of $9.6 million from its deferred tax asset schedule and has recorded a corresponding decrease to its valuation allowance. When this analysis is finalized, the Company will reassess the amount of net operating losses and federal credits subject to limitation under Section 382. Due to the existence of the valuation allowance, future changes in the deferred tax assets related to these tax attributes will not impact the Company’s effective tax rate.
	The following table summarizes the activity related to the Company’s gross unrecognized tax benefits at the beginning and end of the years ended December 31, 2014, 2013 and 2012 (in thousands):
		December 31,
		2014			2013			2012
	Gross unrecognized tax benefits at the beginning of the year	$	6,396		$	3,239		$	3,134
	Increases related to current year tax positions		960			1,167			105
	Decreases related to prior year tax positions		(35	)		1,990			—
	Expiration of unrecognized tax benefits		(12	)		—			—
	Gross unrecognized tax benefits at the end of the year	$	7,309		$	6,396		$	3,239
	Due to the valuation allowance, none of the unrecognized tax benefits as of December 31, 2014, if recognized, would reduce the Company’s annual effective tax rate. The Company expects approximately $115,600 of unrecognized tax benefits will reverse over the next 12 months.
	The Company files income tax returns in the United States and in various state jurisdictions with varying statutes of limitations. Due to net operating losses incurred, the Company’s tax returns from inception to date are subject to examination by taxing authorities. The Company’s policy is to recognize interest expense and penalties related to income tax matters as a component of income tax expense. As of December 31, 2014, the Company had no interest or penalties accrued for uncertain tax positions.

Litigation

Litigation	12 Months Ended
	Dec. 31, 2014
Litigation	11. Litigation
	In May 2013, the Company received a shareholder demand alleging that certain option grants to the Company’s President and Chief Executive Officer, Michael A. Narachi, the Company’s Chief Business Officer and acting-Chief Financial Officer, Joseph P. Hagan, and the Company’s Senior Vice President, General Counsel and Secretary, Heather D. Turner, in 2011 were granted in excess of the 1,500,000 share limit set forth in Section 3.3 of the 2007 Plan as to the number of shares of the Company’s common stock with respect to which one or more stock awards may be granted to any one eligible participant during any of the Company’s fiscal years. The Company refers to this limit as the 162(m) Award Limit. The Company’s board of directors established a demand review committee composed of independent directors to conduct an investigation with respect to the shareholder demand and to make recommendations to the Company’s board of directors. The demand review committee engaged independent counsel as part of its investigation and evaluated (1) the terms of the 2007 Plan, (2) the initial issuance procedures for the option grants to Mr. Narachi, Mr. Hagan and Ms. Turner during 2011, (3) the authority available to the compensation committee of the Company’s board of directors under its charter and the 2007 Plan, (4) the expectations of the award recipients and (5) the intent of the Company’s board of directors and the compensation committee regarding the availability of an exemption from the deductibility limitations of Section 162(m) of the Internal Revenue Code for such option grants. Following its investigation, the demand review committee determined that the 162(m) Award Limit first became effective as of September 2, 2011, and that, therefore, awards granted under the 2007 Plan prior to September 2, 2011, did not count toward the 162(m) Award Limit. The demand review committee determined that the awards granted to Mr. Hagan between September 2, 2011 and December 31, 2011 did not exceed the 162(m) Award Limit. The demand review committee further determined that the options granted to Mr. Narachi and Ms. Turner, including the portion of such awards in excess of the 162(m) Award Limit, were validly approved under the 2007 Plan, although the portion of those awards in excess of the 162(m) Award Limit does not qualify as performance-based compensation under Section 162(m). In September 2013, the compensation committee amended the 2007 Plan, with the approval of the Company’s board of directors, to take the following actions: (1) to clarify that the 162(m) Award Limit only applies to awards or the portion thereof intended to qualify as performance-based compensation under Section 162(m); and (2) to confirm that the compensation committee has the authority to make awards in excess of the 162(m) Award Limit, which the Company refers to as the Plan Amendment. The Plan Amendment is deemed effective as of September 10, 2011, consistent with the authority of the compensation committee as administrator of the 2007 Plan as of that date. Any grants under the 2007 Plan in excess of the 162(m) Award Limit are not intended to qualify as performance-based compensation under Section 162(m).
	On December 6, 2013, a plaintiff claiming to be a shareholder of ours filed a derivative lawsuit purportedly on behalf of us against certain of our officers and the members of our board of directors, in the Superior Court for the State of California, County of San Diego, captioned Wilkin v. Narachi, et al. On December 9, 2013, the same shareholder who made a demand on the board in May 2013 filed a derivative lawsuit purportedly on behalf of us against certain of our officers and current and former members of our board of directors in the United States District Court, for the Southern District of California, captioned Turgeman v. Narachi, et al. Both of the lawsuits assert claims for breach of fiduciary duty, waste and unjust enrichment based on, among other things, the alleged grant of stock options to certain officers in excess of the 162(m) Award Limit, repricing stock options allegedly in violation of our equity incentive plan, the board of directors’ conduct in responding to the May 2013 shareholder demand, and making allegedly false and misleading statements. Both of the lawsuits seek, among other things, declaratory relief, corporate governance reforms, rescission of certain stock option awards, rescission of the Plan Amendment, injunctive relief, damages, restitution, disgorgement and attorney’s fees. On July 23, 2014, we and the individual defendants filed a motion to dismiss the Turgeman complaint. The judge has not yet ruled on the motion. The Company and the individual defendants filed a motion to dismiss the Wilkin complaint on August 13, 2014. On October 24, 2014, the judge granted the motion to dismiss with leave to amend the complaint. The plaintiff did not file an amended complaint within the court-ordered deadline but filed a motion to stay the action. On January 29, 2015, the judge denied the motion to stay and dismissed the lawsuit with prejudice. On February 6, 2015, the parties filed a stipulation with the court in which plaintiff waived his right to appeal and the parties agreed to a judgment dismissing the lawsuit. The Company is awaiting the judge’s signature on the final judgment. Although management believes that the claims lack merit and intends to defend against them vigorously, there are uncertainties inherent in any litigation and we cannot predict the outcome.

Employee_Benefit_Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2014
Employee Benefit Plan	12. Employee Benefit Plan
	The Company has a defined contribution 401(k) retirement plan which allows employees to contribute up to 100% of their annual compensation up to the maximum annual amount prescribed by the Internal Revenue Service. The Company may elect to make a discretionary contribution or match a discretionary percentage of employee contributions. During the years ended December 31, 2014, 2013 and 2012, the Company’s matching contributions to the plan were approximately $275,000, $262,000 and $153,000, respectively.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2014
Selected Quarterly Financial Data	13. Selected Quarterly Financial Data (Unaudited)
	The following financial information reflects all normal recurring adjustments, which are, in the opinion of management, necessary for a fair statement of the results of the interim periods. Selected quarterly financial data for years ended December 31, 2014 and 2013 are as follows (in thousands, except per share amounts):
			Year Ended December 31, 2014
			1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
	Selected quarterly financial data:
	Revenues		$	857		$	857		$	30,857		$	22,950
	Total operating expenses			24,011			23,659			17,816			20,565
	Net income (loss)			(24,898	)		(24,507	)		11,273			607
	Net income (loss) per share-basic and diluted(1)		$	(0.23	)	$	(0.21	)	$	0.09		$	0
			Year Ended December 31, 2013
			1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
	Selected quarterly financial data:
	Revenues		$	857		$	857		$	857		$	857
	Total operating expenses			20,255			19,120			19,438			21,813
	Net loss			(19,368	)		(18,246	)		(18,572	)		(21,485	)
	Net loss per share-basic and diluted(1)		$	(0.21	)	$	(0.19	)	$	(0.19	)	$	(0.21	)
	-1	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly net loss per share will not necessarily equal the total for the year.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Use of Estimates	Use of Estimates
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents
	The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents.
Investment Securities, Available-for-Sale	Investment Securities, Available-for-Sale
	The Company classifies all investment securities as available-for-sale, as the sale of such securities may be required prior to maturity to implement management strategies. These investment securities are carried at fair value, with unrealized gains and losses reported as accumulated other comprehensive income (loss) until realized. The cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion, as well as interest and dividends, are included in interest income. Realized gains and losses from the sale of available-for-sale securities, if any, are determined on a specific identification basis and are also included in interest income.
Restricted Cash	Restricted Cash
	As of December 31, 2014, restricted cash represents a certificate of deposit pledged as collateral for a letter of credit issued by the Company in connection with the execution of an operating lease.
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	The carrying amount of cash and cash equivalents, accounts payable and accrued expenses are considered to be representative of their respective fair value because of the short-term nature of these items. Investment securities, available-for-sale, are carried at fair value.
Concentration of Credit Risk	Concentration of Credit Risk
	Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and investment securities, available-for-sale. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. However, management believes the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which these deposits are held. Additionally, the Company has established guidelines regarding the diversification of its investments and their maturities, which are designed to maintain safety and liquidity.
Concentration of Revenue and Accounts Receivable	Concentration of Revenue and Accounts Receivable
	Takeda accounted for 100% of revenue for each of the years ended December 31, 2014, 2013 and 2012. Takeda also accounted for 100% of our accounts receivable as of December 31, 2014 and 2013.
Property and Equipment	Property and Equipment
	Property and equipment is stated at cost and depreciated over the estimated useful lives of the assets (three to five years) using the straight-line method. Leasehold improvements are stated at cost and amortized over the shorter of their useful lives or the lease term.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets
	The Company will record impairment losses on long-lived assets used in operations when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. The Company has not recognized any impairment losses as of December 31, 2014.
Research and Development Costs	Research and Development Costs
	All research and development costs are charged to expense as incurred and consist principally of costs related to clinical trials, license fees and salaries and related benefits. Clinical trial costs are a significant component of research and development expenses. These costs are accrued based on estimates of work performed, and require estimates of total costs incurred based on patients enrolled, progress of clinical studies and other events. Clinical trial costs are subject to revision as the trials progress and revisions are charged to expense in the period in which they become known.
Patent Costs	Patent Costs
	All costs related to filing and pursuing patent applications are expensed as incurred as recoverability of such expenditures is uncertain.
Inventory	Inventory
	Inventories are stated at the lower of cost (using a first-in, first-out basis) or market. Inventory costs including raw materials and finished goods that may be associated with its products prior to regulatory approval are charged to research and development expense prior to such approval on a country-specific basis.
Income Taxes	Income Taxes
	Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities using enacted tax rates which will be in effect when the differences reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax asset will be realized.
	The Company follows the provisions of the Income Taxes Topic of the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification that defines a recognition threshold and measurement attributes for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. Under the Income Taxes Topic, the impact of an uncertain income tax position on the income tax return must be recognized at the largest amount that is more-likely-than-not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained.
Revenue Recognition	Revenue Recognition
	The Company has entered into agreements with Takeda which contain multiple elements, including nonrefundable upfront fees, payments associated with achieving specific development milestones and royalties based on specified percentages of net product sales, if any.
	Prior to the revised multiple element and milestone method of revenue recognition guidance adopted by the Company on January 1, 2011, nonrefundable, up-front license fees and milestone payments with standalone value that are not dependent on any future performance by the Company under the agreements were recognized as revenue upon the earlier of when payments were received or collection was assured, but were deferred if the Company had continuing performance obligations. If the Company had continuing involvement through contractual obligations under such agreements, such up-front fees were deferred and recognized over the period for which the Company continued to have a performance obligation. The collaboration agreement with Takeda has continuing obligations, and as a result the up-front fees were deferred upon receipt.
	Effective January 1, 2011, for multiple element agreements entered into or materially modified after December 31, 2010, the Company follows the provisions of Accounting Standards Update (“ASU”) No. 2009-13. In order to account for the multiple-element arrangements, the Company identifies the deliverables included within the agreement 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. A delivered item is considered a separate unit of accounting when the delivered item has value to the partner on a standalone basis based on the consideration of the relevant facts and circumstances for each arrangement. Factors considered in this determination include the research capabilities of the partner and the availability of research expertise in this field in the general marketplace. Arrangement consideration is allocated at the inception of the agreement to all identified units of accounting based on their relative selling price. The relative selling price for each deliverable is determined using vendor-specific objective evidence (“VSOE”) of selling price or third-party evidence of selling price if VSOE does not exist. If neither VSOE nor third-party evidence of selling price exists, we use our best estimate of the selling price for the deliverable. The amount of allocable arrangement consideration is limited to amounts that are fixed or determinable. The consideration received is allocated among the separate units of accounting, and the applicable revenue recognition criteria are applied to each of the separate units. Changes in the allocation of the sales price between delivered and undelivered elements can impact revenue recognition but do not change the total revenue recognized under any agreement. Upfront license fee payments are recognized upon delivery of the license if facts and circumstances dictate that the license has standalone value from the undelivered items, which generally include research and development services and the manufacture of drug products, the relative selling price allocation of the license is equal to or exceeds the upfront license fee, persuasive evidence of an arrangement exists, the Company’s price to the partner is fixed or determinable, and collectability is reasonably assured.
	Upfront license fee payments are deferred if facts and circumstances dictate that the license does not have standalone value. The determination of the length of the period over which to defer revenue is subject to judgment and estimation and can have a material impact on the amount of revenue recognized in a given period.
	The terms of the Company’s partnership agreements provide for milestone payments upon achievement of certain regulatory/development and sales-based events. Effective January 1, 2011, the Company adopted on a prospective basis the guidance under ASU No. 2010-17, “Revenue Recognition-Milestone Method”. Under the Milestone Method of accounting, the Company recognizes consideration that is contingent upon the achievement of a milestone in its entirety as revenue in the period in which the milestone is achieved only if the milestone is substantive in its entirety. A milestone is considered substantive when it meets all of the following three criteria: 1) The consideration is commensurate with either the entity’s performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the entity’s performance to achieve the milestone, 2) The consideration relates solely to past performance, and 3) The consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. A milestone is defined as an event (i) that can only be achieved based in whole or in part on either the entity’s performance or on the occurrence of a specific outcome resulting from the entity’s performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved and (iii) that would result in additional payments being due to the Company. Any milestone payments received prior to satisfying these revenue recognition criteria were recorded as deferred revenue in the accompanying consolidated financial statements.
	Royalties to be received based on sales of the Company’s licensed products by partners will be recognized as earned.
Convertible Senior Notes	Convertible Senior Notes
	In December 2013, the Company issued $115.0 million in aggregate principal amount of 2.75% convertible senior notes due 2020 (the “2020 Notes”). The 2020 Notes are accounted for in accordance with FASB ASC 470, formerly FSP APB 14-1, Accounting for Convertible Debt Instruments That May be Settled in Cash upon Conversion (Including Partial Cash Settlement). ASC Subtopic 470-20 requires the issuer of convertible debt that may be settled in shares or cash upon conversion at their option, such as the 2020 Notes, to account for the liability (debt) and equity (conversion option) components separately. The guidance requires the carrying amount of the liability component to be estimated by measuring the fair value of a similar liability that does not have an associated conversion feature. To measure the fair value of the liability component, the Company used an income approach, discounting the future contractual cash flows due under the 2020 Notes by a market interest rate. The market interest rate was determined to be 8.69%. Assumptions used in the estimate represent what market participants would use in pricing the liability component, including market interest rates, credit standing, and yield curves, all of which are defined as Level 2 observable inputs. The estimated implied interest rate was applied to the 2020 Notes, which resulted in a fair value of the liability component of $79.7 million upon issuance, calculated as the present value of implied future payments based on the $115.0 million aggregate principal amount. The $31.3 million difference between the cash proceeds of $111.0 million and the estimated fair value of the liability component was recorded in additional paid-in capital as the 2020 Notes. The liability component will be accreted to redemption value over the term of the 2020 Notes.
Stock-Based Compensation	Stock-Based Compensation
	The Company measures and recognizes compensation expense for all stock-based payment awards made to employees, non-employee directors and consultants, including stock options and employee stock purchases related to the Company’s 2013 Employee Stock Purchase Plan, based on estimated fair values. Compensation costs related to all equity instruments granted are recognized at the grant-date fair value of the awards. Additionally, the Company includes an estimate of the number of awards that will be forfeited in calculating compensation costs, which is recognized over the requisite service period of the awards on a straight-line basis. No related tax benefits of the share-based compensation costs have been recognized since the Company’s inception.
	The fair value of each option award was estimated on the date of grant using the Black-Scholes option valuation model. The following weighted-average assumptions were utilized for the calculations during each period:
		Years Ended December 31,
		2014			2013			2012
	Expected life (in years)		5.6			6			6
	Expected volatility		107.3	%		92.7	%		87.5	%
	Risk-free interest rate		1.8	%		1.2	%		1.1	%
	Expected dividend yield		0	%		0	%		0	%
	Per share grant-date fair value	$	5.01		$	4.35		$	2.26
	The weighted average expected life of an award is based on historical forfeiture experience, exercise activity, and on the terms and conditions of the stock awards. The expected volatility is based on the historical volatility of the Company’s common stock over the most recent period commensurate with the estimated expected term of the stock awards. The risk-free interest rate assumption was based on the United States Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued. The assumed dividend yield was based on the Company’s expectation of not paying dividends in the foreseeable future.
	Total stock-based compensation expense recognized during the years ended December 31, 2014, 2013 and 2012 was comprised of the following (in thousands):
		Years Ended December 31,
		2014			2013			2012
	General and administrative	$	10,842		$	8,162		$	5,755
	Research and development		4,454			3,405			1,815
		$	15,296		$	11,567		$	7,570
	At December 31, 2014, total unrecognized estimated share-based compensation expense related to non-vested stock options granted prior to that date was $26.7 million, which is expected to be recognized over a weighted-average period of 1.8 years.
Comprehensive Loss	Comprehensive Loss
	The Company records all components of comprehensive income, including net income, in the financial statements in the period in which they are recognized. Comprehensive loss consists of net loss and certain changes in stockholders’ equity that are excluded from net loss. Comprehensive loss for each of the years ended December 31, 2014, 2013 and 2012 has been reflected in the Statements of Comprehensive Loss. Accumulated other comprehensive income (loss), which is included in stockholders’ equity, represents unrealized gains and losses on investment securities, available-for-sale.
	Comprehensive loss includes net loss and unrealized gains and losses on investments. The Company discloses the accumulated balance of other comprehensive loss as a separate component of stockholder’s equity.
Net Loss Per Share	Net Loss Per Share
	The Company computes basic loss per share by dividing the net loss available to common stockholders by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss assumes the conversion, exercise or issuance of all potential common stock equivalents, unless the effect of inclusion would be anti-dilutive. For purposes of this calculation, common stock equivalents include the Company’s stock options and Employee Stock Purchase Plan (ESPP), warrants and the shares to be issued upon the conversion of the convertible senior notes. No shares related to the assumed conversion of the convertible senior notes were included in the diluted net loss calculation for the years ended December 31, 2014, 2013 and 2012 because the inclusion of such shares would have had an anti-dilutive effect. The shares to be issued upon exercise of certain outstanding stock options and common stock warrants were excluded from the diluted net loss calculation for all periods presented because such shares are anti-dilutive.
	(In thousands, except per share amounts)	Years Ended December 31,
		2014			2013			2012
	Historical
	Numerator:
	Net loss	$	(37,525	)	$	(77,671	)	$	(90,094	)
	Denominator:
	Weighted average common shares outstanding		118,240			96,491			70,739
	Denominator for basic and diluted net loss per share		118,240			96,491			70,739
	Net loss per share—basic and diluted	$	(0.32	)	$	(0.80	)	$	(1.27	)
	Historical outstanding anti-dilutive securities not included in the diluted net loss per share calculation include the following (in thousands):
		As of December 31,
		2014			2013			2012
	Shares underlying convertible senior notes		14,042			14,042			—
	Common stock warrants outstanding		572			17,870			37,768
	Common stock options outstanding		17,959			16,902			13,839
			32,573			48,814			51,607
Recently Issued Accounting Standards	Recently Issued Accounting Standards
	In May 2014, the FASB issued new accounting guidance related to revenue recognition. This new standard will replace all current generally accepted accounting principles guidance on this topic and eliminate all industry-specific guidance. The new revenue recognition standard provides a unified model to determine when and how revenue is recognized. The core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration for which the entity expects to be entitled in exchange for those goods or services. This guidance will be effective for fiscal years beginning after December 16, 2016, including interim periods within that reporting period, and can be applied either retrospectively to each period presented or as a cumulative-effect adjustment as of the date of adoption. Early adoption is prohibited. The Company is evaluating the impact of adopting this new accounting standard on its financial statements and related disclosures.

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Assumptions Used and Resulting Estimates of Weighted-Average Fair Value Per Share	The fair value of each option award was estimated on the date of grant using the Black-Scholes option valuation model. The following weighted-average assumptions were utilized for the calculations during each period:
		Years Ended December 31,
		2014			2013			2012
	Expected life (in years)		5.6			6			6
	Expected volatility		107.3	%		92.7	%		87.5	%
	Risk-free interest rate		1.8	%		1.2	%		1.1	%
	Expected dividend yield		0	%		0	%		0	%
	Per share grant-date fair value	$	5.01		$	4.35		$	2.26
Summary of Information about Stock Options Outstanding	The following table summarizes stock option activity for the 2004 and 2007 Plans:
		Number of			Weighted Average
		Options			Exercise Price
	Outstanding at December 31, 2011		10,586,379		$	1.92
	Granted		4,268,125			3.1
	Exercised		(997,608	)		1.74
	Forfeited		(18,002	)		3.44
	Outstanding at December 31, 2012		13,838,894		$	2.29
	Granted		4,069,507			5.77
	Exercised		(616,184	)		1.78
	Forfeited/Cancelled		(390,070	)		4.38
	Outstanding at December 31, 2013		16,902,147		$	3.1
	Granted		3,194,512			6.22
	Exercised		(1,111,552	)		2.07
	Forfeited		(1,026,138	)		5.35
	Outstanding at December 31, 2014		17,958,969		$	3.59
Summary of Information about Stock Options Outstanding	The following table summarizes information about stock options outstanding under the 2007 Plan at December 31, 2014:
		Options Outstanding									Options Exercisable
	Range of	Number of			Weighted			Weighted			Number of		Weighted
	Exercise Prices	Options			Average			Average			Options		Average
					Remaining			Exercise Price					Exercise Price
					Contractual Life
					(In Years)
	$1.61 - $1.66		5,261,871			6.6		$	1.66			4,210,658	$	1.66
	$1.70 - $2.58		4,559,386			6.7		$	2.21			3,585,808	$	2.18
	$3.12 - $5.69		4,537,814			7.1		$	5.08			2,746,256	$	4.84
	$5.73 - $8.18		3,599,898			8.6		$	6.29			1,296,225	$	6.38
	$1.61 - $8.18		17,958,969			7.2		$	3.59			11,838,947	$	3.07
Common Stock Reserved for Future Issuance	Common stock reserved for future issuance consists of the following at December 31, 2014:
	Common stock warrants		572,040
	Available for future issuance under ESPP		5,870,390
	Stock options issued and outstanding		17,958,969
	Authorized for future option grants		7,769,668
			32,171,067
ESPP
Assumptions Used and Resulting Estimates of Weighted-Average Fair Value Per Share	The assumptions used for the years ended December 31, 2014 and 2013 and the resulting estimates of weighted-average fair value per share for stock purchased under the ESPP during 2014 and 2013 are as follows:
		Years Ended
		December 31,
		2014		2013
	Expected term (in years)	0.49 – 2.00		0.45 – 1.95
	Expected volatility	49.1 – 72.9%		46.6 – 72.8%
	Risk-free interest rate	0.06 – 0.49%		0.07 – 0.26%
	Expected dividend yield	0.00%		0.00%

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Stock Based Compensation Expense	Total stock-based compensation expense recognized during the years ended December 31, 2014, 2013 and 2012 was comprised of the following (in thousands):
		Years Ended December 31,
		2014			2013			2012
	General and administrative	$	10,842		$	8,162		$	5,755
	Research and development		4,454			3,405			1,815
		$	15,296		$	11,567		$	7,570
Earnings Per Share	The shares to be issued upon exercise of certain outstanding stock options and common stock warrants were excluded from the diluted net loss calculation for all periods presented because such shares are anti-dilutive.
	(In thousands, except per share amounts)	Years Ended December 31,
		2014			2013			2012
	Historical
	Numerator:
	Net loss	$	(37,525	)	$	(77,671	)	$	(90,094	)
	Denominator:
	Weighted average common shares outstanding		118,240			96,491			70,739
	Denominator for basic and diluted net loss per share		118,240			96,491			70,739
	Net loss per share—basic and diluted	$	(0.32	)	$	(0.80	)	$	(1.27	)
Historical Outstanding Anti Dilutive Securities not Included in Diluted Net Loss Per Share Calculation	Historical outstanding anti-dilutive securities not included in the diluted net loss per share calculation include the following (in thousands):
		As of December 31,
		2014			2013			2012
	Shares underlying convertible senior notes		14,042			14,042			—
	Common stock warrants outstanding		572			17,870			37,768
	Common stock options outstanding		17,959			16,902			13,839
			32,573			48,814			51,607

Investment_Securities_Availabl1

Investment Securities, Available-for-Sale (Tables)	12 Months Ended
	Dec. 31, 2014
Estimated Fair Value of Investment Securities, Available-for-Sale	A summary of the estimated fair value of investment securities, available-for-sale, is as follows at December 31, 2014 and December 31, 2013 (in thousands):
	December 31, 2014	Maturity in Years	Amortized		Unrealized					Fair
			Cost		Gains		Losses			Value
	U.S. government agency securities	Less than 1	$	87,895	$	4	$	(27	)	$	87,872
	Corporate debt securities	Less than 1		5,074		—		(1	)		5,073
	U.S. government agency securities	More than 1		8,351		—		(2	)		8,349
	Total investment securities		$	101,320	$	4	$	(30	)	$	101,294
	December 31, 2013	Maturity in Years	Amortized		Unrealized					Fair
			Cost		Gains		Losses			Value
	U.S. government agency securities	Less than 1	$	77,877	$	4	$	(7	)	$	77,874
	U.S. Treasury securities	Less than 1		1,001		—		—			1,001
	Total investment securities		$	78,878	$	4	$	(7	)	$	78,875

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Assets Measured at Fair Value on Recurring Basis	Assets that have recurring measurements are shown below (in thousands):
				Fair Value Measurement at Reporting Date Using
	Description	Balance as of		Quoted Prices in		Significant Other		Significant
		December 31,		Active Markets		Observable		Unobservable
		2014		for Identical		Inputs (Level 2)		Inputs (Level 3)
				Assets (Level 1)
	Financial instruments owned:
	Money market funds	$	97,966	$	97,966	$	—	$	—
	U.S. government agency securities		100,720		—		100,720		—
	Corporate debt securities		5,073		—		5,073		—
	Total financial instruments owned	$	203,759	$	97,966	$	105,793	$	—
				Fair Value Measurement at Reporting Date Using
	Description	Balance as of		Quoted Prices in		Significant Other		Significant
		December 31,		Active Markets		Observable		Unobservable
		2013		for Identical		Inputs (Level 2)		Inputs (Level 3)
				Assets (Level 1)
	Financial instruments owned:
	Money market funds	$	96,910	$	96,910	$	—	$	—
	U.S. Treasury securities		1,001		—		1,001		—
	U.S. government agency securities		77,874		—		77,874		—
	Total financial instruments owned	$	175,785	$	96,910	$	78,875	$	—

Inventory_Tables

Inventory (Tables)	12 Months Ended
	Dec. 31, 2014
Components of Inventory	Inventory consists of the following (in thousands):
		December 31,
		2014		2013
	Raw materials	$	755	$	—
	Work in process		58		—
	Finished goods		385		—
		$	1,198	$	—

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property and Equipment	Property and equipment consists of the following (in thousands):
			December 31,
		Useful Life in Years	2014			2013
	Furniture and fixtures	5	$	1,079		$	1,079
	Computer equipment and software	3 to 5		521			422
	Leasehold improvements	5		557			557
	Manufacturing equipment	5		640			—
	Asset under construction			120			518
				2,917			2,576
	Accumulated depreciation			(2,060	)		(1,946	)
	Property and equipment, net		$	857		$	630

Accrued_Expenses_Tables

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2014
Accrued Expenses	Accrued expenses consist of the following (in thousands):
		December 31,
		2014		2013
	Accrued compensation related expenses	$	4,666	$	4,774
	Accrued research and development expenses		1,187		1,273
	Accrued interest on convertible notes		264		220
	Accrued legal and professional expenses		156		355
	Other accrued expenses		279		129
		$	6,552	$	6,751

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Reconciliation of Income Taxes to Amounts Computed by Applying Statutory Federal Income Tax Rate to Net Loss	A reconciliation of income taxes to the amount computed by applying the statutory federal income tax rate to the net loss is summarized as follows:
		December 31,
	(In thousands)	2014			2013			2012
	Income tax expense (benefit) at statutory rates	$	(13,133	)	$	(27,184	)	$	(31,532	)
	State income tax, net of federal benefit		(422	)		(4,242	)		(5,073	)
	Permanent items		2,157			804			379
	Uncertain tax positions		843			2,629			69
	Research and development credits		(2,041	)		(5,492	)		(344	)
	Stock-based compensation		751			760			447
	Change in rate		(2,624	)		—			(20	)
	Change in valuation allowance		14,469			32,725			36,074
	Income tax expense (benefit)	$	—		$	—		$	—
Deferred Tax Assets
		December 31,
	(In thousands)	2014			2013
	Deferred tax assets:
	Net operating loss carryforwards	$	55,035		$	63,794
	Research and development credits		5,988			4,752
	Capitalized research and development expenditures		2,439			2,859
	Deferred revenue		34,205			15,716
	Stock-based compensation		10,911			8,919
	Other, net		2,409			1,884
	Total deferred tax assets		110,987			97,924
	Valuation allowance for deferred tax assets		(99,807	)		(85,330	)
	Deferred tax assets, net of valuation allowance		11,180			12,594
	Deferred tax liabilities:
	Convertible debt		(11,180	)		(12,594	)
	Total deferred tax liabilities		(11,180	)		(12,594	)
		$	—		$	—
Activity Related to Gross Unrecognized Tax Benefits	The following table summarizes the activity related to the Company’s gross unrecognized tax benefits at the beginning and end of the years ended December 31, 2014, 2013 and 2012 (in thousands):
		December 31,
		2014			2013			2012
	Gross unrecognized tax benefits at the beginning of the year	$	6,396		$	3,239		$	3,134
	Increases related to current year tax positions		960			1,167			105
	Decreases related to prior year tax positions		(35	)		1,990			—
	Expiration of unrecognized tax benefits		(12	)		—			—
	Gross unrecognized tax benefits at the end of the year	$	7,309		$	6,396		$	3,239
CALIFORNIA
Schedule of Expirations of Net Operating Loss Carry Forwards	The California net operating loss carry forwards are scheduled to expire as follows (in thousands):
	Year	Amount
	2015	$	4,557
	2016		20,936
	2017		49,842
	2018		3,841
	2028 and beyond		311,309

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2014
Selected Quarterly Financial Data	The following financial information reflects all normal recurring adjustments, which are, in the opinion of management, necessary for a fair statement of the results of the interim periods. Selected quarterly financial data for years ended December 31, 2014 and 2013 are as follows (in thousands, except per share amounts):
			Year Ended December 31, 2014
			1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
	Selected quarterly financial data:
	Revenues		$	857		$	857		$	30,857		$	22,950
	Total operating expenses			24,011			23,659			17,816			20,565
	Net income (loss)			(24,898	)		(24,507	)		11,273			607
	Net income (loss) per share-basic and diluted(1)		$	(0.23	)	$	(0.21	)	$	0.09		$	0
			Year Ended December 31, 2013
			1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
	Selected quarterly financial data:
	Revenues		$	857		$	857		$	857		$	857
	Total operating expenses			20,255			19,120			19,438			21,813
	Net loss			(19,368	)		(18,246	)		(18,572	)		(21,485	)
	Net loss per share-basic and diluted(1)		$	(0.21	)	$	(0.19	)	$	(0.19	)	$	(0.21	)
	-1	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly net loss per share will not necessarily equal the total for the year.

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Basis Of Presentation And Organization [Line Items]
Accumulated deficit	($552,000)	($514,475)

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary Of Significant Accounting Policies [Line Items]
Uncertain income tax position recognition criteria, minimum percentage of likelihood of being sustained	50.00%
Proceeds from issuance of convertible notes		110,545,000
Unrecognized Share based compensation expense related to non-vested stock option	26,700,000
Unrecognized Share based compensation expense related to non vested stock option, weighted-average recognition period	1 year 9 months 18 days
2.75% convertible senior notes due 2020
Summary Of Significant Accounting Policies [Line Items]
Aggregate principal amount convertible notes		115,000,000
Interest rate		2.75%
Carrying value of equity component, net of issuance costs	31,178,000	31,178,000
2.75% convertible senior notes due 2020 | Significant Other Observable Inputs (Level 2)
Summary Of Significant Accounting Policies [Line Items]
Aggregate principal amount convertible notes		115,000,000
Interest rate		2.75%
Market interest rate	8.69%	8.69%
Fair value of liability component upon issuance	79,700,000	79,700,000
Carrying value of equity component, net of issuance costs	31,300,000	31,300,000
Proceeds from issuance of convertible notes	111,000,000	111,000,000
Takeda Pharmaceutical Company Limited | Customer Concentration Risk | Sales
Summary Of Significant Accounting Policies [Line Items]
Percentage concentration risk	100.00%	100.00%	100.00%
Takeda Pharmaceutical Company Limited | Customer Concentration Risk | Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Percentage concentration risk	100.00%	100.00%
Maximum
Summary Of Significant Accounting Policies [Line Items]
Highly liquid investments, maturities	3 months
Estimated useful lives of Property and equipment	Five years
Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of Property and equipment	Three years

Weighted_Average_Assumptions_o

Weighted Average Assumptions of Options Granted (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	5 years 7 months 6 days	6 years	6 years
Expected volatility	107.30%	92.70%	87.50%
Risk-free interest rate	1.80%	1.20%	1.10%
Expected dividend yield	0.00%	0.00%	0.00%
Per share grant-date fair value	$5.01	$4.35	$2.26

Stock_Based_Compensation_Expen

Stock- Based Compensation Expense (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total Stock-Based Compensation Expense	$15,296	$11,567	$7,570
General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total Stock-Based Compensation Expense	10,842	8,162	5,755
Research and Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total Stock-Based Compensation Expense	$4,454	$3,405	$1,815

Earnings_Per_Share_Detail

Earnings Per Share (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	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
Numerator:
Net loss	$607	$11,273	($24,507)	($24,898)	($21,485)	($18,572)	($18,246)	($19,368)	($37,525)	($77,671)	($90,094)
Denominator:
Weighted average common shares outstanding									118,240	96,491	70,739
Weighted average common shares outstanding									118,240	96,491	70,739
Net loss per share-basic and diluted									($0.32)	($0.80)	($1.27)

Historical_Outstanding_Anti_Di

Historical Outstanding Anti Dilutive Securities not Included in Diluted Net Loss Per Share Calculation (Detail)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock warrants/ options outstanding	32,573	48,814	51,607
Convertible Senior Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock warrants/ options outstanding	14,042	14,042
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock warrants/ options outstanding	572	17,870	37,768
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock warrants/ options outstanding	17,959	16,902	13,839

Estimated_Fair_Value_of_Invest

Estimated Fair Value of Investment Securities, Available-for-Sale (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$101,320	$78,878
Unrealized Gains	4	4
Unrealized Losses	-30	-7
Fair Value	101,294	78,875
U.S. Treasury Securities | Mature In Less Than One Year
Schedule of Available-for-sale Securities [Line Items]
Maturity in Years		Less than 1
Amortized Cost		1,001
Fair Value		1,001
U.S. Government Agency Securities | Mature In Less Than One Year
Schedule of Available-for-sale Securities [Line Items]
Maturity in Years	Less than 1	Less than 1
Amortized Cost	87,895	77,877
Unrealized Gains	4	4
Unrealized Losses	-27	-7
Fair Value	87,872	77,874
U.S. Government Agency Securities | Mature In More Than One Year
Schedule of Available-for-sale Securities [Line Items]
Maturity in Years	More than 1
Amortized Cost	8,351
Unrealized Losses	-2
Fair Value	8,349
Corporate Debt Securities | Mature In Less Than One Year
Schedule of Available-for-sale Securities [Line Items]
Maturity in Years	Less than 1
Amortized Cost	5,074
Unrealized Losses	-1
Fair Value	$5,073

Assets_that_have_Recurring_Mea

Assets that have Recurring Measurements (Detail) (Fair Value, Measurements, Recurring, USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned	$203,759	$175,785
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned	97,966	96,910
U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned		1,001
U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned	100,720	77,874
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned	5,073
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned	97,966	96,910
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned	97,966	96,910
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned	105,793	78,875
Significant Other Observable Inputs (Level 2) | U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned		1,001
Significant Other Observable Inputs (Level 2) | U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned	100,720	77,874
Significant Other Observable Inputs (Level 2) | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial instruments owned	$5,073

Components_of_Inventory_Detail

Components of Inventory (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Inventory [Line Items]
Raw materials	$755
Work in process	58
Finished goods	385
Inventory	$1,198

Property_and_Equipment_Detail

Property and Equipment (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Gross total	$2,917	$2,576
Accumulated depreciation	-2,060	-1,946
Property and equipment, net	857	630
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Useful Life In Years	5 years
Gross total	1,079	1,079
Computer Equipment and Software
Property, Plant and Equipment [Line Items]
Gross total	521	422
Computer Equipment and Software | Minimum
Property, Plant and Equipment [Line Items]
Useful Life In Years	3 years
Computer Equipment and Software | Maximum
Property, Plant and Equipment [Line Items]
Useful Life In Years	5 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Useful Life In Years	5 years
Gross total	557	557
Manufacturing Equipment
Property, Plant and Equipment [Line Items]
Useful Life In Years	5 years
Gross total	640
Asset under Construction
Property, Plant and Equipment [Line Items]
Gross total	$120	$518

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Depreciation expense	$139	$94	$313

Accrued_Expenses_Detail

Accrued Expenses (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts Payable and Accrued Liabilities [Line Items]
Accrued compensation related expenses	$4,666	$4,774
Accrued research and development expenses	1,187	1,273
Accrued interest on convertible notes	264	220
Accrued legal and professional expenses	156	355
Other accrued expenses	279	129
Accrued expenses	$6,552	$6,751

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Oct. 31, 2014	Sep. 30, 2010	Jun. 30, 2003	Mar. 31, 2012
Commitments and Contingencies [Line Items]
Proceeds from issuance of convertible notes		$110,545,000
Certificate of deposit used a collateral for letter credit	177,000	177,000		177,000
Operating lease, rent expense	911,000	1,100,000	1,400,000
Revenue recognized	54,229,000	3,428,000	3,428,000
Deferred revenue	8,229,000	3,429,000		3,429,000
Royalties earned for the sale of Contrave	1,292,000
2.75% convertible senior notes due 2020
Commitments and Contingencies [Line Items]
Aggregate principal amount convertible notes		115,000,000		115,000,000
Interest rate		2.75%		2.75%
Debt Issuance Cost				488,000
Debt Instrument, Term				7 years
Convertible notes initial conversion rate	122.1225
Convertible notes, initial conversion rate principal amount	1,000
Convertible notes, initial conversion price per share	$8.19
Debt instrument, maturity date				1-Dec-20
Repurchase of notes description	On and after September 1, 2020 until the close of business on the business day immediately preceding the maturity date, holders may convert all or a portion of their 2020 Notes at any time, regardless of the foregoing circumstances.
Debt instrument, interest payment terms	The Company pays 2.75% interest per annum on the principal amount of the 2020 Notes semi-annually in arrears in cash on June 1 and December 1 of each year, beginning on June 1, 2014.
Carrying value of equity component, net of issuance costs	31,178,000	31,178,000		31,178,000
During Any Fiscal Quarter Commencing After March 31, 2014 | 2.75% convertible senior notes due 2020
Commitments and Contingencies [Line Items]
Threshold consecutive trading days				30 days
During Any Fiscal Quarter Commencing After March 31, 2014 | 2.75% convertible senior notes due 2020 | Minimum
Commitments and Contingencies [Line Items]
Threshold trading days				20
Convertible, threshold percentage of stock price trigger				130.00%
During The Five Consecutive Business Day Period | 2.75% convertible senior notes due 2020
Commitments and Contingencies [Line Items]
Threshold consecutive trading days				10 days
Number of business day period				5 days
Required repurchase percentage on principal amount				100.00%
During The Five Consecutive Business Day Period | 2.75% convertible senior notes due 2020 | Maximum
Commitments and Contingencies [Line Items]
Convertible, threshold percentage of stock price trigger				98.00%
Significant Other Observable Inputs (Level 2) | 2.75% convertible senior notes due 2020
Commitments and Contingencies [Line Items]
Aggregate principal amount convertible notes		115,000,000		115,000,000
Interest rate		2.75%		2.75%
Estimated implied interest rate	8.69%	8.69%		8.69%
Fair value of liability component upon issuance	79,700,000	79,700,000		79,700,000
Carrying value of equity component, net of issuance costs	31,300,000	31,300,000		31,300,000
Proceeds from issuance of convertible notes	111,000,000	111,000,000
Collaborative Arrangement | Takeda Pharmaceutical Company Limited
Commitments and Contingencies [Line Items]
Non-refundable upfront payment						50,000,000
Additional payments eligible	1,000,000,000
Amount achievable between execution of collaboration agreement and first commercial sale	100,000,000
Remaining additional eligible payments	900,000,000
Remaining additional eligible payments related to anniversary payments	45,000,000
Anniversary payment period	3 years
Tiered royalty payments, Minimum	20.00%
Tiered royalty payments, Maximum	35.00%
Deferred upfront payment	50,000,000
Estimated term of agreement	14 years 6 months					14 years 6 months
Milestones earned	30,000,000				70,000,000
Revenue recognized	20,800,000
Deferred revenue	49,200,000
Royalties earned for the sale of Contrave	1,300,000
Revenue recognized	55,500,000	3,400,000	3,400,000
Deferred revenue	84,300,000	38,600,000		38,600,000
Reimbursement receivables	2,600,000	77,000		77,000
Reimbursements of manufacturing expenses	7,600,000	0
Milestone payments due to company upon regulatory approval	20,000,000
Milestone payments due to the Company upon the delivery of launch supplies	10,000,000
Milestone payment due to the Company upon the first commercial sale	70,000,000
Payable related to clinical study	6,500,000
License Agreement | Oregon Health & Science University
Commitments and Contingencies [Line Items]
License agreement, upfront fee							65,000
License agreement, shares issued							76,315
Royalty payable recorded	65,000
License agreement, percentage of maintenance and prosecution expense paid by the company	100.00%
License agreement, payment in connection with maintenance and prosecution of patent	118,000
License agreement, notice period for not file any patent application or to abandon any patent or patent application	60 days
Estimated year of patent expiration	2024
License Agreement | Oregon Health & Science University | Upon Receipt of a Pair of Mice
Commitments and Contingencies [Line Items]
License agreement, payment	20,000
License Agreement | Oregon Health & Science University | Upon Receipt of Any Additional Pair of Mice
Commitments and Contingencies [Line Items]
License agreement, payment	20,000
Corporate Headquarters
Commitments and Contingencies [Line Items]
Operating lease, beginning period	2008-04
Operating lease, term	64 years
Operating lease, ending period	2017-09
Operating lease, termination fee								190,849
Corporate Headquarters | Certificates of Deposit
Commitments and Contingencies [Line Items]
Certificate of deposit used a collateral for letter credit	$177,000
Corporate Headquarters | Additional Office Space Lease
Commitments and Contingencies [Line Items]
Operating lease, term	52 months

Equity_and_Liability_Component

Equity and Liability Components of Notes (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Disclosure Equity Components [Line Items]
Long term convertible debt	$83,908	$80,031
2.75% convertible senior notes due 2020
Disclosure Equity Components [Line Items]
Principal amount of senior convertible notes outstanding	115,000	115,000
Unamortized discount of liability component	-31,092	-34,969
Long term convertible debt	83,908	80,031
Carrying value of equity component, net of issuance costs	$31,178	$31,178
Remaining amortization period of discount on the liability component	6 years	7 years

Future_Minimum_Payments_Under_

Future Minimum Payments Under Operating Leases (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Operating Lease Obligations [Line Items]
2015	$1,053
2016	1,085
2017	742
2018	0
2019	0
Total	$2,880

Stockholders_Equity_Additional

Stockholders Equity - Additional Information (Detail) (USD $)

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

Oct. 31, 2012

Dec. 31, 2011

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Mar. 31, 2011

Dec. 31, 2004

Jul. 31, 2011

Jun. 30, 2011

Jan. 31, 2011

Jan. 31, 2010

Jan. 31, 2009

Apr. 30, 2007

Feb. 28, 2010

Oct. 31, 2009

Jul. 25, 2011

Jul. 22, 2011

Installment

Stockholders Equity Note Disclosure [Line Items]

Public offering, number of units issued

5,646,173

Public offering, number of common stock shares in each unit

1

Public offering, number of common stock shares in each warrant

10

Common stock shares issued, price per share

$5.50

$1.45

Warrant price to purchase each share of common stock

$1.45

Public offering, price per unit

$15.94

Net cash proceeds from the public offering

$86,900,000

Warrant exercise price

0.001

Warrant exercisable period

10 years

Warrant exercisable commencement date

22-Dec-11

Warrants, number of common stock shares available for purchase

56,461,730

Common stock shares issued

11,000,000

Net cash proceeds from issuance of common stock shares

56,500,000

2,734,000

1,337,000

58,270,000

Stock plan, maximum term of options granted

5 years 7 months 6 days

6 years

6 years

Stock plan, option outstanding

10,586,379

17,958,969

16,902,147

13,838,894

Stock plan, option granted

3,194,512

4,069,507

4,268,125

Stock-based compensation expense, recognition period

1 year 9 months 18 days

Aggregate intrinsic value of options outstanding

45,300,000

Aggregate intrinsic value of options exercisable

35,800,000

Weighted average remaining contractual term for options exercisable

6 years 8 months 12 days

Aggregate intrinsic value of options exercised

3,600,000

3,100,000

4,600,000

Maximum

Stockholders Equity Note Disclosure [Line Items]

Excess percentage of common stock outstanding

9.99%

Warrants outstanding

572,040

17,869,618

37,767,900

Stock plan, maximum term of options granted

2 years

1 year 11 months 12 days

Stock Option Repricing Program

Stockholders Equity Note Disclosure [Line Items]

Stock plan, option outstanding

1,443,150

Option exercise price

$2.94

Stock-based compensation expense to be recognized over vesting period

819,000

Stock-based compensation expense, recognition period

4 years

Stock Option Repricing Program | September 2010 Grants

Stockholders Equity Note Disclosure [Line Items]

Stock plan, option outstanding

492,357

Option vesting commencement date

18-Jan-11

Stock Option Repricing Program | September 2010 Grants | Original Exercise Price

Stockholders Equity Note Disclosure [Line Items]

Option exercise price

$5.89

Stock Option Repricing Program | January 2011 Grants

Stockholders Equity Note Disclosure [Line Items]

Stock plan, option outstanding

950,793

Option vesting commencement date

18-Jan-11

Stock Option Repricing Program | January 2011 Grants | Original Exercise Price

Stockholders Equity Note Disclosure [Line Items]

Option exercise price

$9.31

2004 Plan

Stockholders Equity Note Disclosure [Line Items]

Stock plan, common stock reserved for issuance

3,159,275

Stock plan, option vesting period

4 years

Stock plan, option outstanding

0

2004 Plan | Maximum

Stockholders Equity Note Disclosure [Line Items]

Stock plan, maximum term of options granted

10 years

Stock Option Exchange Program

Stockholders Equity Note Disclosure [Line Items]

Stock plan, option vesting period

4 years

Option exercise price

$1.66

Stock plan, number of installments for option vesting

48

Stock-based compensation expense to be recognized over vesting period

2,700,000

Stock-based compensation expense, recognition period

4 years

Stock Option Exchange Program | Stock Options Exchanged

Stockholders Equity Note Disclosure [Line Items]

Stock plan, exercisable number of shares of options

7,407,634

Stock Option Exchange Program | New Option Issued

Stockholders Equity Note Disclosure [Line Items]

Option exercise price

$1.66

Stock plan, exercisable number of shares of options

7,407,634

Employee Stock Purchase Plan

Stockholders Equity Note Disclosure [Line Items]

Stock plan, common stock reserved for issuance

6,000,000

Stock-based compensation expense, recognition period

9 months

Employee Stock Purchase Plan (ESPP), payroll deductions as percentage of participant's cash compensation

15.00%

Employee Stock Purchase Plan (ESPP), Purchase price

85.00%

Employee Stock Purchase Plan (ESPP), Offering Period duration

24 months

Employee Stock Purchase Plan (ESPP), Offering Period description

Each Offering Period consists of four (4) six month purchase periods (each a "Purchase Period") during which payroll deductions of the participants are accumulated under the ESPP. The last business day of each Purchase Period is referred to as the "Purchase Date." Purchase Dates are every six months on the last business day of May and November.

Shares issued under Employee Stock Purchase Plan (ESPP)

84,325

45,285

Unrecognized share based compensation expense

$326,000

2007 Plan

Stockholders Equity Note Disclosure [Line Items]

Stock plan, common stock reserved for issuance

3,525,000

Stock plan, maximum term of options granted

10 years

Stock plan, option outstanding

17,958,969

Stock plan, additional common stock reserved for issuance

10,000,000

2,000,000

2,000,000

1,721,666

Stock plan, option granted

17,958,969

2007 Plan | Automatically Each January 1

Stockholders Equity Note Disclosure [Line Items]

Stock plan, additional common stock reserved for issuance

6,000,000

Stock plan, percentage of common stock outstanding

15.00%

2007 Plan | Non Employee Directors

Stockholders Equity Note Disclosure [Line Items]

Stock plan, additional common stock reserved for issuance

40,000,000

2,000,000

500,000

Warrants

Stockholders Equity Note Disclosure [Line Items]

Common stock shares issued

17,294,521

19,895,061

11,130,548

Summary_of_Stock_Option_Activi

Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Number of Options
Outstanding beginning balance	16,902,147	13,838,894	10,586,379
Granted	3,194,512	4,069,507	4,268,125
Exercised	-1,111,552	-616,184	-997,608
Forfeited	-1,026,138		-18,002
Forfeited/Cancelled		-390,070
Outstanding ending balance	17,958,969	16,902,147	13,838,894
Weighted Average Exercise Price
Beginning balance	$3.10	$2.29	$1.92
Granted	$6.22	$5.77	$3.10
Exercised	$2.07	$1.78	$1.74
Forfeited	$5.35		$3.44
Forfeited/Cancelled		$4.38
Ending balance	$3.59	$3.10	$2.29

Summary_of_Information_about_S

Summary of Information about Stock Options Outstanding (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Options	17,958,969	16,902,147	13,838,894	10,586,379
Options Outstanding, Weighted Average Exercise Price	$3.59	$3.10	$2.29	$1.92
2007 Plan
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Options	17,958,969
2007 Plan | $1.61 - $1.66
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower range	$1.61
Range of Exercise Price, upper range	$1.66
Options Outstanding, Number of Options	5,261,871
Options Outstanding, Weighted Average Remaining Contractual Life (In Years)	6 years 7 months 6 days
Options Outstanding, Weighted Average Exercise Price	$1.66
Options Exercisable, Number of Options	4,210,658
Option Exercisable, Weighted Average Exercise Price	$1.66
2007 Plan | $1.70 - $2.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower range	$1.70
Range of Exercise Price, upper range	$2.58
Options Outstanding, Number of Options	4,559,386
Options Outstanding, Weighted Average Remaining Contractual Life (In Years)	6 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price	$2.21
Options Exercisable, Number of Options	3,585,808
Option Exercisable, Weighted Average Exercise Price	$2.18
2007 Plan | $3.12 - $5.69
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower range	$3.12
Range of Exercise Price, upper range	$5.69
Options Outstanding, Number of Options	4,537,814
Options Outstanding, Weighted Average Remaining Contractual Life (In Years)	7 years 1 month 6 days
Options Outstanding, Weighted Average Exercise Price	$5.08
Options Exercisable, Number of Options	2,746,256
Option Exercisable, Weighted Average Exercise Price	$4.84
2007 Plan | $5.73 - $8.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower range	$5.73
Range of Exercise Price, upper range	$8.18
Options Outstanding, Number of Options	3,599,898
Options Outstanding, Weighted Average Remaining Contractual Life (In Years)	8 years 7 months 6 days
Options Outstanding, Weighted Average Exercise Price	$6.29
Options Exercisable, Number of Options	1,296,225
Option Exercisable, Weighted Average Exercise Price	$6.38
2007 Plan | $1.61 - $8.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Price, lower range	$1.61
Range of Exercise Price, upper range	$8.18
Options Outstanding, Number of Options	17,958,969
Options Outstanding, Weighted Average Remaining Contractual Life (In Years)	7 years 2 months 12 days
Options Outstanding, Weighted Average Exercise Price	$3.59
Options Exercisable, Number of Options	11,838,947
Option Exercisable, Weighted Average Exercise Price	$3.07

Estimated_Weighted_Average_Fai

Estimated Weighted Average Fair Value per Share (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	5 years 7 months 6 days	6 years	6 years
Expected volatility, minimum	49.10%	46.60%
Expected volatility,maximum	72.90%	72.80%
Risk-free interest rate, minimum	0.06%	0.07%
Risk-free interest rate, maximum	0.49%	0.26%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	5 months 27 days	5 months 12 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	2 years	1 year 11 months 12 days

Common_Stock_Reserved_for_Futu

Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2014
Stockholders Equity Note [Line Items]
Common stock reserved for future issuance	32,171,067
Warrants
Stockholders Equity Note [Line Items]
Common stock reserved for future issuance	572,040
Employee Stock Purchase Plan
Stockholders Equity Note [Line Items]
Common stock reserved for future issuance	5,870,390
Stock Options Issue and Outstanding
Stockholders Equity Note [Line Items]
Common stock reserved for future issuance	17,958,969
Future Option Grants
Stockholders Equity Note [Line Items]
Common stock reserved for future issuance	7,769,668

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Line Items]
Federal income tax expense	$0	$0	$0
State income tax expense	0	0	0
Deferred tax assets for net operating losses, federal	398,100,000
Deferred tax assets for net operating losses, state	390,900,000
Deferred tax assets for research and development credits	5,988,000	4,752,000
Net operating loss carry forwards related to excess tax deductions for stock compensation	55,035,000	63,794,000
Net operating loss and research and development tax credit carry forwards limitation on use, minimum percentage of ownership change	50.00%
Net operating loss and research and development tax credit carry forwards limitation on use, period for ownership change	3 years
Unrecognized tax benefits that would reduce the Company's annual effective tax rate if recognized	0
Unrecognized tax benefits expected to reverse over the next 12 months.	115,600
Federal
Income Taxes [Line Items]
Operating loss carry forward expiration date	2024
Deferred tax assets for research and development credits	18,500,000
Federal | Research And Development Tax Credit Carryforward
Income Taxes [Line Items]
Operating loss carry forward expiration date	2024
State
Income Taxes [Line Items]
Deferred tax assets for research and development credits	5,500,000
Subject to Section 382 and 383 of the Internal Revenue Code of 1986 Limitations
Income Taxes [Line Items]
Deferred tax assets for net operating losses, federal	254,100,000
Deferred tax assets for net operating losses, state	231,100,000
Deferred tax assets for research and development credits	9,600,000
Deferred Compensation, Share-based Payments
Income Taxes [Line Items]
Net operating loss carry forwards related to excess tax deductions for stock compensation	$11,400,000

Reconciliation_of_Income_Taxes

Reconciliation of Income Taxes to Amounts Computed by Applying Statutory Federal Income Tax Rate to Net Loss (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation Of Income Taxes [Line Items]
Income tax expense (benefit) at statutory rates	($13,133)	($27,184)	($31,532)
State income tax, net of federal benefit	-422	-4,242	-5,073
Permanent items	2,157	804	379
Uncertain tax positions	843	2,629	69
Research and development credits	-2,041	-5,492	-344
Stock-based compensation	751	760	447
Change in rate	-2,624		-20
Change in valuation allowance	14,469	32,725	36,074
Income tax expense (benefit)	$0	$0	$0

Deferred_Tax_Assets_Detail

Deferred Tax Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred tax assets:
Net operating loss carryforwards	$55,035	$63,794
Research and development credits	5,988	4,752
Capitalized research and development expenditures	2,439	2,859
Deferred revenue	34,205	15,716
Stock-based compensation	10,911	8,919
Other, net	2,409	1,884
Total deferred tax assets	110,987	97,924
Valuation allowance for deferred tax assets	-99,807	-85,330
Deferred tax assets, net of valuation allowance	11,180	12,594
Deferred tax liabilities:
Convertible debt	-11,180	-12,594
Total deferred tax liabilities	-11,180	-12,594
Deferred Tax Assets, Net, Total	$0	$0

Summary_of_Net_Operating_Loss_

Summary of Net Operating Loss Carryforwards (Detail) (CALIFORNIA, USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
2015
Operating Loss Carryforwards [Line Items]
Amount of net operating loss carryforward expected to expire	$4,557
2016
Operating Loss Carryforwards [Line Items]
Amount of net operating loss carryforward expected to expire	20,936
2017
Operating Loss Carryforwards [Line Items]
Amount of net operating loss carryforward expected to expire	49,842
2018
Operating Loss Carryforwards [Line Items]
Amount of net operating loss carryforward expected to expire	3,841
2028 and beyond
Operating Loss Carryforwards [Line Items]
Amount of net operating loss carryforward expected to expire	$311,309

Activity_Related_to_Gross_Unre

Activity Related to Gross Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Unrecognized Tax Benefits [Line Items]
Gross unrecognized tax benefits at the beginning of the year	$6,396	$3,239	$3,134
Increases related to current year tax positions	960	1,167	105
Decreases related to prior year tax positions	-35	1,990
Expiration of unrecognized tax benefits	-12
Gross unrecognized tax benefits at the end of the year	$7,309	$6,396	$3,239

Litigation_Additional_Informat

Litigation - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014
Litigation [Line Items]
Share based compensation plan award maximum number of shares granted per eligible participant	1,500,000

Employee_Benefit_Plan_Addition

Employee Benefit Plan - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Benefit Plan [Line Items]
Employee benefit plan, employee contribution percentage	100.00%
Employee benefit plan, matching contribution	$275,000	$262,000	$153,000

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (Detail) (USD $)	3 Months Ended																12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	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
Quarterly Financial Data [Line Items]
Revenues	$22,950		$30,857		$857		$857		$857		$857		$857		$857		$55,521	$3,428	$3,428
Total operating expenses	20,565		17,816		23,659		24,011		21,813		19,438		19,120		20,255		86,051	80,626	93,667
Net income (loss)	$607		$11,273		($24,507)		($24,898)		($21,485)		($18,572)		($18,246)		($19,368)		($37,525)	($77,671)	($90,094)
Net income (loss) per share-basic and diluted	$0	[1]	$0.09	[1]	($0.21)	[1]	($0.23)	[1]	($0.21)	[1]	($0.19)	[1]	($0.19)	[1]	($0.21)	[1]	($0.32)	($0.80)	($1.27)
[1]	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly net loss per share will not necessarily equal the total for the year.