Viracta Therapeutics (VIRX) 10-K 12 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 27, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
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	SNSS
Entity Registrant Name	SUNESIS PHARMACEUTICALS INC
Entity Central Index Key	1061027
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		67,739,771
Entity Public Float			$263,889,528

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$22,186	$15,121
Marketable securities	20,795	24,172
Prepaids and other current assets	1,223	1,199
Total current assets	44,204	40,492
Property and equipment, net	42	23
Deposits and other assets		10
Total assets	44,246	40,525
Current liabilities:
Accounts payable	3,177	953
Accrued clinical expense	3,112	4,750
Accrued compensation	2,287	1,719
Other accrued liabilities	3,087	1,645
Current portion of deferred revenue	3,418	7,956
Current portion of notes payable	9,257	9,018
Warrant liability	3,543	7,931
Total current liabilities	27,881	33,972
Non-current portion of deferred revenue	2,563	3,712
Non-current portion of notes payable		9,025
Commitments and contingencies (Note 9)
Stockholders’ equity (deficit):
Common stock, $0.0001 par value; 400,000 shares authorized as of December 31, 2014; 66,102 and 54,344 shares issued and outstanding as of December 31, 2014 and 2013, respectively	7	5
Additional paid-in capital	536,499	473,509
Accumulated other comprehensive loss	-7	-3
Accumulated deficit	-522,697	-479,695
Total stockholders’ equity (deficit)	13,802	-6,184
Total liabilities and stockholders’ equity (deficit)	$44,246	$40,525

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	66,102,000	54,344,000
Common stock, shares outstanding	66,102,000	54,344,000

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue:
License and other revenue	$5,734	$7,956	$3,754
Total revenues	5,734	7,956	3,754
Operating expenses:
Research and development	27,665	28,891	29,185
General and administrative	23,112	10,838	9,175
Total operating expenses	50,777	39,729	38,360
Loss from operations	-45,043	-31,773	-34,606
Interest expense	-1,719	-2,917	-1,855
Other income (expense), net	3,760	92	-7,490
Net loss	-43,002	-34,598	-43,951
Unrealized (loss) gain on available-for-sale securities	-4	-41	19
Comprehensive loss	-43,006	-34,639	-43,932
Net loss:
Basic	-43,002	-34,598	-43,951
Diluted	($46,894)	($34,598)	($43,951)
Shares used in computing net loss per common share:
Basic	60,057	52,249	48,146
Diluted	61,510	52,249	48,146
Net loss per common share:
Basic	($0.72)	($0.66)	($0.91)
Diluted	($0.76)	($0.66)	($0.91)

CONSOLIDATED_STATEMENTS_OF_STO

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) (USD $)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
In Thousands, except Share data
Beginning Balance at Dec. 31, 2011	$28,020	$5	$429,142	$19	($401,146)
Beginning Balance, shares at Dec. 31, 2011		46,774,000
Issuance of common stock through controlled equity offering facilities, net of issuance costs	17,620		17,620
Issuance of common stock through controlled equity offering facilities, net of issuance costs, shares		3,714,000
Issuance of common stock pursuant to warrant exercises	3,130		3,130
Issuance of common stock pursuant to warrant exercises, shares		801,000
Issuance of common stock pursuant to stock option exercises	330		330
Issuance of common stock pursuant to stock option exercises, shares		146,000
Issuance of common stock under employee stock purchase plans	172		172
Issuance of common stock under employee stock purchase plans, shares		84,000
Issuance of common stock to employees, shares		46,000
Issuance of warrants to purchase common stock	3,893		3,893
Stock-based compensation expenses—employees	2,402		2,402
Stock-based compensation expenses—non-employees	322		322
Net loss	-43,951				-43,951
Unrealized gain (loss) on available-for-sale securities	19			19
Ending Balance at Dec. 31, 2012	11,957	5	457,011	38	-445,097
Ending Balance, shares at Dec. 31, 2012		51,565,000
Issuance of common stock through controlled equity offering facilities, net of issuance costs	11,986		11,986
Issuance of common stock through controlled equity offering facilities, net of issuance costs, shares		2,535,000
Issuance of common stock pursuant to warrant exercises	88		88
Issuance of common stock pursuant to warrant exercises, shares		18,000
Issuance of common stock pursuant to stock option exercises	230		230
Issuance of common stock pursuant to stock option exercises, shares		104,000
Issuance of common stock under employee stock purchase plans	309		309
Issuance of common stock under employee stock purchase plans, shares		97,000
Issuance of common stock to employees, shares		25,000
Stock-based compensation expenses—employees	3,581		3,581
Stock-based compensation expenses—non-employees	304		304
Net loss	-34,598				-34,598
Unrealized gain (loss) on available-for-sale securities	-41			-41
Ending Balance at Dec. 31, 2013	-6,184	5	473,509	-3	-479,695
Ending Balance, shares at Dec. 31, 2013	54,344,000	54,344,000
Issuance of $43,013 of common stock and warrants in underwritten offering, net of issuance costs of $2990	40,024	1	40,023
Issuance of common stock and warrants in underwritten offering, net of issuance costs, shares		4,650,000
Issuance of common stock through controlled equity offering facilities, net of issuance costs	14,292	1	14,291
Issuance of common stock through controlled equity offering facilities, net of issuance costs, shares		5,114,000
Issuance of common stock pursuant to warrant exercises	949		949
Issuance of common stock pursuant to warrant exercises, shares		1,323,000
Issuance of common stock pursuant to stock option exercises	1,226		1,226
Issuance of common stock pursuant to stock option exercises, shares	565,000	566,000
Issuance of common stock under employee stock purchase plans	282		282
Issuance of common stock under employee stock purchase plans, shares	99,049,000	99,000
Issuance of common stock to employees, shares		6,000
Stock-based compensation expenses—employees	5,882		5,882
Stock-based compensation expenses—non-employees	337		337
Net loss	-43,002				-43,002
Unrealized gain (loss) on available-for-sale securities	-4			-4
Ending Balance at Dec. 31, 2014	$13,802	$7	$536,499	($7)	($522,697)
Ending Balance, shares at Dec. 31, 2014	66,102,000	66,102,000

CONSOLIDATED_STATEMENTS_OF_STO1

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement Of Stockholders Equity [Abstract]
Issuance of common stock through controlled equity offering facilities	$14,734	$12,357	$18,124
Issuance of common stock through controlled equity offering facilities, issuance costs	442	371	504
Issuance of common stock and warrants in underwritten offering	43,013
Issuance of common stock and warrants in underwritten offering, issuance costs	$2,989

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net loss	($43,002)	($34,598)	($43,951)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	6,219	3,885	2,724
Depreciation and amortization	29	20	31
Amortization of debt discount and debt issuance costs	367	621	400
(Decrease) increase in fair value of warrant liability	-3,892	-96	7,509
Foreign exchange gain on marketable securities		-142	-82
Gain on sale of property and equipment			-11
Changes in operating assets and liabilities:
Prepaids and other assets	-43	489	-98
Accounts payable	2,224	875	-580
Accrued clinical expense	-1,638	-699	3,079
Accrued compensation	568	254	191
Other accrued liabilities	1,674	-76	522
Deferred revenue	-5,687	-7,956	19,624
Net cash used in operating activities	-43,181	-37,423	-10,642
Cash flows from investing activities
Purchases of property and equipment	-48
Proceeds from sale of property and equipment			11
Purchases of marketable securities	-42,463	-26,894	-67,608
Proceeds from maturities of marketable securities	45,836	59,110	46,226
Net cash provided by (used in) investing activities	3,325	32,216	-21,371
Cash flows from financing activities
Proceeds from notes payable, net			14,982
Principal payments on notes payable	-9,356	-7,182
Proceeds from issuance of common stock and warrants in underwritten offering, net	40,024
Proceeds from issuance of common stock through controlled equity offering facilities, net	14,292	11,986	17,620
Fair value of warrants issued in connection with royalty agreement			3,122
Proceeds from exercise of warrants, stock options and stock purchase rights	1,961	584	1,918
Net cash provided by financing activities	46,921	5,388	37,642
Net increase (decrease) in cash and cash equivalents	7,065	181	5,629
Cash and cash equivalents at beginning of period	15,121	14,940	9,311
Cash and cash equivalents at end of period	22,186	15,121	14,940
Supplemental disclosure of cash flow information
Interest paid	1,221	2,006	1,165
Supplemental disclosure of non-cash activities
Transfer of fair value of exercised warrants to additional paid-in capital	496	43	1,715
Fair value of warrants issued in connection with notes payable			770
Cashless exercise of warrants	$9,337		$402

Company_Overview

Company Overview	12 Months Ended
	Dec. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Company Overview
	1. Company Overview
	Description of Business
	Sunesis Pharmaceuticals, Inc. (the “Company” or “Sunesis”) was incorporated in the state of Delaware on February 10, 1998, and its facilities are located in South San Francisco, California. Sunesis is a biopharmaceutical company focused on the development and commercialization of new oncology therapeutics for the treatment of solid and hematologic cancers. The Company’s primary activities since incorporation have been conducting research and development internally and through corporate collaborators, in-licensing and out-licensing pharmaceutical compounds and technology, conducting clinical trials and raising capital.
	In October 2014, the Company announced the results of a Phase 3, multi-national, randomized, double-blind, placebo-controlled, clinical trial of vosaroxin in combination with cytarabine in patients with relapsed or refractory acute myeloid leukemia (the “VALOR trial”). The trial did not meet its primary endpoint of demonstrating a statistically significant improvement in overall survival, but based upon the favorable results of other predefined analyses of the data, Sunesis plans to meet with European regulatory authorities in preparation for the filing of a marketing authorization application (“MAA”) with the European Medicines Agency (“EMA”) in the second half of 2015. The Company is also currently engaged in discussions with the U.S. Food and Drug Administration (“FDA”) to determine a potential regulatory path forward in the United States.
	Significant Risks and Uncertainties
	The Company has incurred significant losses and negative cash flows from operations since its inception, and as of December 31, 2014, had cash, cash equivalents and marketable securities totaling $43.0 million and an accumulated deficit of $522.7 million.
	The Company will need to raise substantial additional capital to pursue a regulatory strategy for the potential commercialization of QINPREZOTM (vosaroxin), its product candidate for the potential treatment of acute myeloid leukemia, and to continue the development of vosaroxin and the Company’s other programs. The Company expects to finance its future cash needs primarily through equity issuances, debt arrangements, one or more possible licenses, collaborations or other similar arrangements with respect to development and/or commercialization rights to vosaroxin and its other development programs, or a combination of the above. However, the Company does not know whether additional funding will be available on acceptable terms, or at all. If the Company is unable to raise required funding on acceptable terms or at all, it will need to reduce operating expenses, enter into a collaboration or other similar arrangement with respect to development and/or commercialization rights to vosaroxin, outlicense intellectual property rights to vosaroxin or our other development programs, sell unsecured assets, or a combination of the above, or be forced to delay or reduce the scope of our vosaroxin development program, potentially including any regulatory filings related to the VALOR trial, and/or limit or cease our operations.
	Concentrations of Credit Risk
	In accordance with its investment policy, the Company invests cash that is not currently being used for operational purposes. The policy allows for the purchase of low risk debt securities issued by: (a) the United States and certain European governments and government agencies, and (b) highly rated banks and corporations, denominated in U.S. dollars, Euros or British pounds, subject to certain concentration limits. The policy limits maturities of securities purchased to no longer than 24 months and the weighted average maturity of the portfolio to 12 months. Management believes these guidelines ensure both the safety and liquidity of any investment portfolio the Company may hold.
	Financial instruments that potentially subject the Company to concentrations of credit risk generally consist of cash, cash equivalents and marketable securities. The Company is exposed to credit risk in the event of default by the institutions holding its cash, cash equivalents and any marketable securities to the extent of the amounts recorded in the balance sheets.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies
	Basis of Presentation
	The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”).
	Recent Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), that will supersede most existing revenue recognition guidance under US GAAP. The core principle of the guidance is that an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. Entities can choose to apply the standard using either the full retrospective approach or a modified retrospective approach. Entities electing the full retrospective adoption will apply the standard to each period presented in the financial statements. This means that entities will have to apply the new guidance as if it had been in effect since the inception of all its contracts with customers presented in the financial statements. Entities that elect the modified retrospective approach will apply the guidance retrospectively only to the most current period presented in the financial statements. This means that entities will have to recognize the cumulative effect of initially applying the new standard as an adjustment to the opening balance of retained earnings at the date of initial application. The new revenue standard will be applied to contracts that are in progress at the date of initial application. The standard will be effective for annual and interim periods beginning after December 15, 2016. The Company has yet to evaluate which adoption method it plans to use or the potential effect of the new standard on its consolidated financial statements.
	In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”), which will require a reporting entity to evaluate, at each annual and interim reporting period, whether there are conditions or events that raise substantial doubt about the reporting entity’s ability to continue as a going concern within one year after the date the financial statements are issued and provide related disclosures. The standard will be effective for annual and interim periods beginning after December 15, 2016, with early adoption permitted. The Company has yet to evaluate the potential effect of the new standard on its consolidated financial statements.
	Principles of Consolidation
	The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Sunesis Europe Limited, a United Kingdom corporation, and Sunesis Pharmaceuticals (Bermuda) Ltd., a Bermuda corporation, as well as a Bermuda limited partnership, Sunesis Pharmaceuticals International LP. All intercompany balances and transactions have been eliminated in consolidation.
	Segment Reporting
	Management has determined that the Company operates as a single reportable segment.
	Significant Estimates and Judgments
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the Company’s consolidated financial statements and accompanying notes thereto. Actual results could differ materially from these estimates. Estimates, assumptions and judgments made by management include those related to the valuation of equity and related instruments, revenue recognition, stock-based compensation and clinical trial accounting.
	Cash Equivalents and Marketable Securities
	The Company considers all highly liquid securities with original maturities of three months or less from the date of purchase to be cash equivalents, which generally consist of money market funds and corporate debt securities. Marketable securities consist of securities with original maturities of greater than three months, which may include U.S. and European government obligations and corporate debt securities.
	Management determines the appropriate classification of securities at the time of purchase. The Company generally classifies its entire investment portfolio as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company classifies all investments as short-term, even though the stated maturity may be more than one year from the current balance sheet date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity (deficit).
	The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in other income (expense), net in the statements of operations and comprehensive loss. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities, if any, are also recorded to other income (expense), net. The cost of securities sold is based on the specific-identification method.
	Invoices for certain services provided to the Company are denominated in foreign currencies. To manage the risk of future movements in foreign exchange rates that would affect such amounts, the Company may purchase certain European currencies or highly-rated investments denominated in those currencies, subject to similar criteria as for other investments defined in the Company’s investment policy. There is no guarantee that the related gains and losses will substantially offset each other, and the Company may be subject to significant exchange gains or losses as currencies fluctuate from quarter to quarter. To date, the Company has purchased Euros and Euro-denominated obligations of foreign governments and corporate debt. As of December 31, 2014 and December 31, 2013, the Company held investments denominated in Euros with an aggregate fair value of $0 and $2.6 million, respectively. Any cash, cash equivalent and short-term investment balances denominated in foreign currencies are recorded at their fair value based on the current exchange rate as of each balance sheet date. The resulting exchange gains or losses and those from amounts payable for services originally denominated in foreign currencies are both recorded in other income (expense), net in the statements of operations and comprehensive loss.
	Fair Value Measurements
	The Company measures cash equivalents, marketable securities and warrant liabilities at fair value on a recurring basis using the following hierarchy to prioritize valuation inputs, in accordance with applicable GAAP:
	Level 1 -	quoted prices (unadjusted) in active markets for identical assets and liabilities that can be accessed at the measurement date
	Level 2 -	inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly
	Level 3 -	unobservable inputs
	The Company’s Level 2 valuations of marketable securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets.
	The fair value of the Company’s liability for warrants issued in connection with an underwritten offering completed in October 2010 (the “2010 Offering”) is determined using the Black-Scholes model, which requires inputs such as the expected term of the warrants, share price volatility, expected dividend yield and risk-free interest rate. As some of these inputs are unobservable, and require significant analysis and judgment to measure, these variables are classified as Level 3.
	The carrying amounts of the Company’s financial instruments, including cash, prepayments, accounts payable, accrued liabilities, deferred revenue and notes payable approximated their fair value as of December 31, 2014 and December 31, 2013.
	Property and Equipment
	Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease.
	Accounting for Royalty Agreement
	The payment of $25.0 million by RPI under the Royalty Agreement (see Note 6) is non-refundable, and no revenue participation right payments will be made unless vosaroxin is commercialized. Accordingly, the payment received from RPI is being accounted for as a payment for the Company to use commercially reasonable efforts to commercialize vosaroxin. Therefore, the amount is to be deferred and recognized as revenue over the projected performance period under the agreement. The payment, less $3.1 million representing the fair value of the warrants granted under the arrangement, was initially classified as deferred revenue and is being amortized to revenue over the related performance period. The fair value of the warrants was recorded to additional paid-in capital.
	Accounting for Notes Payable
	The accounting for certain fees and expenses related to the Loan Agreement (see Note 8) is as follows. The facility fee is being accounted for as a debt discount and classified within notes payable on the Company’s balance sheet. The fair value of the warrants issued in connection with the Loan Agreement have been recorded as a debt discount within notes payable and an increase to additional paid-in capital on the Company’s balance sheet. The debt discount is being amortized as interest expense over the term of the loan using the effective interest method. The final payment is being accreted as interest expense over the term of the loans using the effective interest method. The legal fees are being accounted for as deferred debt issuance costs within assets on the Company’s balance sheet and are being amortized as other income (expense), net over the term of the loans using the effective interest method.
	Accounting for Equity Financing
	In October 2010, the Company completed the 2010 Offering (see Note 10), in which the Company sold its common stock and warrants to purchase its common stock for aggregate gross proceeds of $15.5 million. Due to the potential for the warrants to be settled in cash upon the occurrence of certain transactions specified in the warrant agreements, the warrants are being accounted for as a derivative liability as opposed to permanent equity. Outstanding warrants under this arrangement are revalued to their fair value each period end, with the change in fair value recorded to other income (expense), net in the statements of operations and comprehensive loss.
	Revenue Recognition
	Revenue arrangements with multiple deliverables are accounted for in accordance with the Financial Accounting Standards Board Accounting Standards Codification, Subtopic 605-25, Multiple-Element Arrangements (“ASC 605-25”). Under ASC 605-25, revenue arrangements with multiple deliverables are divided into separate units of accounting based on whether certain criteria are met, including whether the delivered item has stand-alone value to the customer. Consideration is allocated among the separate units of accounting based on their respective fair value, and the applicable revenue recognition is applied to each of the separate units.
	Non-refundable fees where the Company has no continuing performance obligations are recognized as revenues when collection is reasonably assured. In situations where continuing performance obligations exist, non-refundable fees are deferred and recognized ratably over the projected performance period.
	Milestone payments from license or collaboration agreements which are substantive and at risk at the time the agreement is executed are recognized upon completion of the applicable milestone event. Royalty revenues, if any, will be recognized based on reported product sales by third-party licensees. Research funding from any future agreement will be recognized as the related research services are performed.
	Research and Development
	Research and development expense consists primarily of: (a) clinical trial costs, which include payments for work performed by contract research organizations (“CROs”), clinical trial sites, labs and other clinical service providers, and for drug packaging, storage and distribution; (b) drug manufacturing costs, which include costs for producing drug substance and drug product, and for stability and other testing; (c) personnel costs for related permanent and temporary employees; (d) other outside services and consulting costs; and (e) payments under license agreements. All research and development costs are expensed as they are incurred.
	Clinical Trial Accounting
	The Company records accruals for estimated clinical trial costs, which include payments for work performed by CROs and participating clinical trial sites. These costs are generally a significant component of research and development expense. Costs incurred for setting up clinical trial sites for participation in trials are generally non-refundable, and are expensed as incurred, with any refundable advances related to enrollment of the first patient recorded as prepayments and assessed for recoverability on a quarterly basis. Costs related to patient enrollment are accrued as patients progress through the clinical trial, including amortization of any first-patient prepayments. This amortization generally matches when the related services are rendered, however, these cost estimates may or may not match the actual costs incurred by the CROs or clinical trial sites, and if the Company has incomplete or inaccurate information, the clinical trial accruals may not be accurate. The difference between accrued expenses based on the Company’s estimates and actual expenses have not been significant to date.
	Stock-Based Compensation
	The Company grants options to purchase common stock to its employees, directors and consultants under its stock option plans. Under the Company’s Employee Stock Purchase Plan, eligible employees can also purchase shares of the Company’s common stock at 85% of the lower of the fair market value of the Company’s common stock at the beginning of a 12-month offering period or at the end of one of the two related six-month purchase periods.
	The Company values these share-based awards using the Black-Scholes option valuation model (the “Black-Scholes model”). The determination of fair value of share-based payment awards on the date of grant using the Black-Scholes model is affected by the Company’s stock price as well as assumptions regarding a number of highly complex and subjective variables. These variables include, but are not limited to, the expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors and related estimated forfeitures.
	Foreign Currency
	Transactions that are denominated in a foreign currency are translated into U.S. dollars at the current exchange rate on the transaction date. Any foreign currency-denominated monetary assets and liabilities are subsequently remeasured at current exchange rates as of each balance sheet date, with gains or losses on foreign exchange recognized in other income (expense), net in the statements of operations and comprehensive loss.
	Income Taxes
	The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the tax basis of assets and liabilities and their basis for financial reporting. Deferred tax assets or liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which temporary differences are expected to be recovered or settled. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to recognize interest charges and penalties in other income (expense), net in the statements of operations and comprehensive loss.

Loss_per_Common_Share

Loss per Common Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Loss per Common Share	3. Loss per Common Share
	Basic loss per common share is calculated by dividing net loss by the weighted-average number of common shares outstanding for the period. Diluted net loss per common share is computed by dividing (a) net loss, less any anti-dilutive amounts recorded during the period for the change in the fair value of warrant liabilities, by (b) the weighted-average number of common shares outstanding for the period plus dilutive potential common shares as determined using the treasury stock method for options and warrants to purchase common stock.
	The following table sets forth the computation of basic and diluted loss per common share for the periods presented (in thousands, except per share amounts):
		Year Ended December 31,
		2014			2013			2012
	Numerator:
	Net loss—basic	$	(43,002	)	$	(34,598	)	$	(43,951	)
	Adjustment for change in fair value of warrant liability		(3,892	)		—			—
	Net loss—diluted	$	(46,894	)	$	(34,598	)	$	(43,951	)
	Denominator:
	Weighted-average common shares outstanding—basic		60,057			52,249			48,146
	Dilutive effect of warrants		1,453			—			—
	Weighted-average common shares outstanding—diluted		61,510			52,249			48,146
	Net loss per common share:
	Basic	$	(0.72	)	$	(0.66	)	$	(0.91	)
	Diluted	$	(0.76	)	$	(0.66	)	$	(0.91	)
	The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted loss per common share because their inclusion would have had an anti-dilutive effect (in thousands):
		As of December 31,
		2014			2013			2012
	Warrants to purchase shares of common stock		8,978			9,978			10,359
	Options to purchase shares of common stock		10,584			7,611			6,288
	Outstanding securities not included in calculations		19,562			17,589			16,647

Financial_Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Financial Instruments	4. Financial Instruments
	Financial Assets
	The following tables summarize the estimated fair value of the Company’s financial assets measured on a recurring basis as of the dates indicated, which were comprised solely of available-for-sale marketable securities with remaining contractual maturities of one year or less (in thousands):
								Gross		Gross
		Valuation		Amortized				Unrealized		Unrealized			Estimated Fair
	December 31, 2014	Input Level		Cost				Gains		Losses			Value
	Money market funds	Level 1		$	9,287			$	—	$	—		$	9,287
	U.S. certificates of deposit	Level 1			6,360				—		—			6,360
	U.S. corporate debt obligations	Level 2			11,789				—		(7	)		11,782
	U.S. commercial paper	Level 2			2,898				—		—			2,898
	Total available-for-sale securities				30,334				—		(7	)		30,327
	Less amounts classified as cash equivalents				(9,532	)			—		—			(9,532	)
	Amounts classified as marketable securities			$	20,802			$	—	$	(7	)	$	20,795
								Gross		Gross
		Valuation		Amortized				Unrealized		Unrealized			Estimated Fair
	December 31, 2013	Input Level		Cost				Gains		Losses			Value
	Money market funds	Level 1		$	6,282			$	—	$	—		$	6,282
	U.S. corporate debt obligations	Level 2			13,509				—		(4	)		13,505
	U.S. commercial paper	Level 2			8,396				3		—			8,399
	Foreign corporate debt obligations	Level 2			2,571				—		(2	)		2,569
	Total available-for-sale securities				30,758				3		(6	)		30,755
	Less amounts classified as cash equivalents				(6,583	)			—		—			(6,583	)
	Amounts classified as marketable securities			$	24,175			$	3	$	(6	)	$	24,172
	The following table summarizes the available-for-sale securities that were in an unrealized loss position as of December 31, 2014, each having been in such a position for less than 12 months, and none deemed to be other-than-temporarily impaired (in thousands):
		Gross
		Unrealized				Estimated Fair
	December 31, 2014	Losses				Value
	U.S. corporate debt obligations	$	7			$	11,782
	Total available-for-sale securities in an unrealized loss	$	7			$	11,782
	position
	No significant facts or circumstances have arisen to indicate that there has been any deterioration in the creditworthiness of the issuers of these securities. The gross unrealized losses are not considered to be significant and have generally been for relatively short durations. The Company does not intend to sell these securities before maturity and it is not likely that they will need to be sold prior to the recovery of their amortized cost basis. There were no sales of available-for-sale debt securities in the years ended December 31, 2014, 2013 and 2012.
	Financial Liabilities
	The following table summarizes the inputs and assumptions and estimated fair value of the Company’s financial liabilities measured on a recurring basis as of the dates indicated, which were comprised solely of a liability for warrants issued in connection with an underwritten equity offering completed in 2010 (see Note 10):
		December 31,				December 31,
		2014				2013
	Inputs and assumptions:
	Fair market value of Company’s common stock	$	2.55			$	4.74
	Exercise price	$	2.52			$	2.52
	Expected term (years)		0.8				1.8
	Expected volatility		144.9	%			60.8	%
	Risk-free interest rate		0.2	%			0.3	%
	Expected dividend yield		0	%			0	%
	Fair value:
	Estimated fair value per warrant share	$	1.21			$	2.56
	Shares underlying outstanding warrants classified as		2,920				3,099
	liabilities (in thousands)
	Total estimated fair value of outstanding warrants	$	3,543			$	7,931
	(in thousands)
	The warrants have been classified as a liability on the Company’s balance sheet due to the potential for the warrants to be settled in cash upon the occurrence of certain transactions specified in the warrant agreements. At each balance sheet date, the estimated fair value of the outstanding warrants is determined using the Black-Scholes model and recorded to the balance sheet, with the change in fair value recorded to other income (expense), net in the statements of operations and comprehensive loss, and the fair value of warrant exercises transferred to additional paid-in capital. During the year ended December 31, 2014, warrants to purchase 179,427 shares of common stock issued in connection with the 2010 Offering were exercised, resulting in cash proceeds to the Company of $452,000.
	The Black-Scholes model requires Level 3 inputs such as the expected term of the warrants and share price volatility. These inputs are subjective and generally require significant analysis and judgment to develop. Any changes in these inputs could result in a significantly higher or lower fair value measurement.
	The following table summarizes the changes in the fair value of the Company’s Level 3 financial liabilities for the periods indicated (in thousands):
		Warrant
		Liability
	Balance as of December 31, 2012	$	8,070
	Change in fair value of warrant liability		(96	)
	Exercise of warrants		(43	)
	Balance as of December 31, 2013		7,931
	Change in fair value of warrant liability		(3,892	)
	Exercise of warrants		(496	)
	Balance as of December 31, 2014	$	3,543

Other_Accrued_Liabilities

Other Accrued Liabilities	12 Months Ended
	Dec. 31, 2014
Payables And Accruals [Abstract]
Other Accrued Liabilities	5. Other Accrued Liabilities
	Other accrued liabilities as of December 31 were as follows (in thousands):
		2014		2013
	Accrued outside services	$	2,656	$	1,249
	Accrued professional services		355		263
	Other accruals		76		133
	Total other accrued liabilities	$	3,087	$	1,645

Royalty_Agreement

Royalty Agreement	12 Months Ended
	Dec. 31, 2014
Deferred Revenue Disclosure [Abstract]
Royalty Agreement	6. Royalty Agreement
	In March 2012, the Company entered into a Revenue Participation Agreement (the “Royalty Agreement”), with RPI Finance Trust (“RPI”), an entity related to Royalty Pharma. In September 2012, pursuant to the provisions of the Royalty Agreement, RPI made a $25.0 million cash payment to the Company. In conjunction with the Royalty Agreement, we issued two five-year warrants to RPI, each to purchase 1,000,000 shares of our common stock, at exercise prices of $3.48 and $4.64 per share, respectively. Both warrants were net exercised in 2014, resulting in an aggregate issuance of 777,107 shares of common stock. The payment of $25.0 million, less $3.1 million representing the fair value of the warrants granted under the arrangement, was initially classified as deferred revenue and is being amortized to revenue over the related performance period.
	Based on the results of the VALOR trial and the Company’s plans to meet with European regulatory authorities in preparation for the filing of an MAA with the EMA in the second half of 2015 and to continue discussions with the FDA to determine a potential regulatory path forward in the United States, as discussed in Note 1, the Company extended the end date of the estimated performance period through which the balance of deferred revenue will be amortized from June 30, 2015 to September 30, 2016. As a result, the quarterly amortization was adjusted to $0.9 million per quarter, commencing with the quarter ended September 30, 2014, from the previous amortization rate of $2.0 million per quarter.
	Revenue participation right payments will be made to RPI when and if vosaroxin is commercialized, at a rate of 6.75% of net sales of vosaroxin, on a product-by-product and country-by-country basis world-wide through the later of: (a) the expiration of the last to expire of certain specifically identified patents; (b) 10 years from the date of first commercial sale of such product in such country; or (c) the expiration of all applicable periods of data, market or other regulatory exclusivity in such country with respect to such product.

License_Agreements

License Agreements	12 Months Ended
	Dec. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
License Agreements	7. License Agreements
	Overview
	In August 2004, the Company entered into a collaboration agreement with Biogen Idec MA, Inc. (“Biogen Idec”) to discover, develop and commercialize small molecule inhibitors of the human protein Raf kinase, including family members Raf-1, A-Raf, B-Raf and C-Raf (collectively “Raf”) and up to five additional targets that play a role in oncology and immunology indications (the “Biogen Idec OCA”). In connection with the Company’s June 2008 restructuring, the parties agreed to terminate the research obligations and related funding as of June 30, 2008.
	In March 2011, as part of a series of agreements among the Company, Biogen Idec and Millennium Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited, (“Millennium”), the Company entered into: (a) an amended and restated collaboration agreement with Biogen Idec (the “Biogen Idec 1st ARCA”); (b) a license agreement with Millennium (the “Millennium Agreement”); and (c) a termination and transition agreement among the Company, Biogen Idec and Millennium (the “Termination and Transition Agreement”).
	The Termination and Transition Agreement provided for (a) the termination of Biogen Idec’s exclusive rights under the Biogen Idec OCA to all discovery programs under such agreement other than for small molecule inhibitors of the human protein Bruton’s tyrosine kinase (“BTK”); (b) the permitted assignment to Millennium of all related Company collaboration assets and rights to Raf kinase and the human protein phosphoinositide-dependent kinase-1 (“PDK1”); and (c) the payment of $4.0 million upfront from Millennium to the Company, which was recorded as revenue in March 2011.
	Biogen Idec
	The Biogen Idec 1st ARCA amended and restated the Biogen Idec OCA, to provide for the discovery, development and commercialization of small molecule BTK inhibitors. Under this agreement, the Company no longer has research obligations, but licenses granted to Biogen Idec with respect to the research collaboration under the Biogen Idec OCA (other than the licenses transferred to Millennium under the Millennium Agreement) remain in effect.
	In June 2012, the Company received an event-based payment of $1.5 million from Biogen Idec for the advancement of pre-clinical work in connection with the Biogen Idec 1st ARCA. Under this agreement, the Company is eligible to receive up to an additional $58.5 million in pre-commercialization event-based payments related to the development by Biogen Idec of the first two indications for licensed products against the BTK target. The Company is also eligible to receive royalty payments depending on related product sales, if any.
	In December 2013, the Company entered into a second amended and restated collaboration agreement with Biogen Idec (the “Biogen Idec 2nd ARCA”), to provide the Company with an exclusive worldwide license to develop, manufacture and commercialize SNS-062, a BTK inhibitor synthesized under the Biogen Idec 1st ARCA, solely for oncology indications. The Company may be required to make a $2.5 million milestone payment depending on its development of SNS-062 and royalty payments depending on related product sales of SNS-062. All other of Sunesis’ rights and obligations contained in the Biogen Idec 1st ARCA remain unchanged, except that potential future royalty payments to Sunesis were reduced to equal those amounts due to Biogen Idec for potential future sales of SNS-062.
	Millennium
	Under the Millennium Agreement, the Company granted exclusive licenses to products against two oncology targets originally developed under the Biogen Idec OCA, Raf and PDK1, under substantially the same terms as under the Biogen Idec OCA.
	In January 2014, the Company entered into an amended and restated license agreement with Millennium (the “Amended Millennium Agreement”), to provide the Company with an exclusive worldwide license to develop and commercialize preclinical inhibitors of PDK1. In connection with the execution of the Amended Millennium Agreement, the Company paid an upfront fee and may be required to make up to $9.2 million in pre-commercialization milestone payments depending on its development of PDK1 inhibitors and royalty payments depending on related product sales, if any.
	With respect to the Raf target product rights that were originally licensed to Millennium under the Millennium Agreement, the Company may in the future receive up to $57.5 million in pre-commercialization event-based payments related to the development by Millennium of the first two indications for each of the licensed products directed against the Raf target and royalty payments depending on related product sales. Millennium is currently conducting a Phase 1 clinical study of an oral investigative drug, MLN2480, which is licensed to them under the Amended Millennium Agreement.

Notes_Payable

Notes Payable	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Notes Payable	8. Notes Payable
	In October 2011, the Company entered into a Loan and Security Agreement (the “Loan Agreement”) with Oxford Finance LLC, Silicon Valley Bank and Horizon Technology Finance Corporation (collectively, the “Lenders”), under which the Company could borrow up to $25.0 million in two tranches (the “Loan Facility”). The first tranche of $10.0 million was funded upon closing of the transaction in October 2011, and the second tranche of $15.0 million was drawn by the Company in September 2012. In connection with the Loan Agreement, the Lenders were granted a perfected first priority security interest in substantially all of the Company’s assets, other than intellectual property.
	The interest rates for the first and second tranche are 8.95% and 9.00% per annum, respectively. Payments under the Loan Agreement are monthly in arrears and were interest-only until February 1, 2013, followed by 32 equal monthly payments of principal and interest from March 1, 2013 to the scheduled maturity date of October 1, 2015. In addition, a final payment equal to $937,500 will be due on October 1, 2015, or such earlier date as specified in the Loan Agreement. The weighted average annual effective interest rate on the notes payable, including the amortization of the debt discounts and accretion of the final payment, is 13.9%.
	Aggregate future minimum payments due under the Loan Facility as of December 31, 2014 were as follows (in thousands):
	Year ending December 31,	Total
	2015	$	8,814
	Total minimum payments		8,814
	Less amount representing interest		(352	)
	Notes payable, gross		8,462
	Unamortized discount on notes payable		(84	)
	Accretion of final payment		879
	Notes payable, balance		9,257
	Less current portion of notes payable		(9,257	)
	Non-current portion of notes payable	$	—
	On February 27, 2015, the Company entered into a third amendment (the “Amendment”), to the Loan Agreement with the Lenders. The Amendment modifies the loan repayment terms to be interest-only from March 1, 2015 to February 1, 2016, followed by eight equal monthly payments of principal and interest through the new maturity date of October 1, 2016. See Note 14 for further details.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies
	Commitments
	The Company’s operating lease obligations as of December 31, 2014 relate solely to the leasing of office space in a building at 395 Oyster Point Boulevard in South San Francisco, California, which is currently the Company’s headquarters. In January 2014, a lease for 15,378 square feet was entered into with an expiry date of April 30, 2015. In June 2014, the lease was amended to extend the expiration date to June 30, 2015, and to add 6,105 square feet of additional office space within the same building, and in January 2015, the lease was further amended to extend the expiration date to December 31, 2015. The amended lease also includes an option to extend the lease for an additional six months, at a predetermined price, if exercised within a certain period.
	Aggregate non-cancelable future minimum rental payments under the operating lease as of December 31, 2014 were as follows (in thousands):
	Year Ending December 31,	Payments
	2015	$	247
	Total rental payments	$	247
	The Company recognizes rent expense on a straight-line basis. The Company recorded rent expense of $0.4 million, $0.3 million and $0.4 million for the years ended December 31, 2014, 2013 and 2012, respectively.
	Contingencies
	From time to time, the Company may be involved in legal proceedings, as well as demands, claims and threatened litigation, which arise in the normal course of its business or otherwise. The ultimate outcome of any litigation is uncertain and unfavorable outcomes could have a negative impact on the Company’s results of operations and financial condition. Regardless of outcome, litigation can have an adverse impact on the Company because of the defense costs, diversion of management resources and other factors. The Company is not currently involved in any material legal proceedings.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Stockholders' Equity	10. Stockholders’ Equity
	Preferred Stock
	The Company has 10,000,000 shares of authorized preferred stock available for issuance in one or more series. Upon issuance, the Company can determine the rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock. There were no shares of preferred stock outstanding as of December 31, 2014 and 2013.
	Common Stock
	Holders of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders of the Company. Subject to the preferences that may be applicable to any outstanding shares of preferred stock, the holders of common stock are entitled to receive ratably such dividends, if any, as may be declared by the Board of Directors. Under the terms of the Loan Agreement with the Lenders, the Company is precluded from paying cash dividends without the prior written consent of the Lenders.
	Underwritten Offering
	On March 4, 2014, the Company completed an underwritten offering of 4,650,000 shares of common stock, each with two accompanying warrants to purchase one share of the Company’s common stock at exercise prices of $8.50 (Series A) and $12.00 (Series B) per share, respectively. The purchase price for each share of common stock and two accompanying warrants was $9.25. Gross proceeds from the sale were $43.0 million, and net proceeds were $40.0 million, after deducting the underwriting discount and offering expenses.
	The warrants became exercisable on a gross exercise basis upon unblinding of the VALOR trial, which occurred on October 6, 2014. The Series A warrants expired unexercised on December 4, 2014. The Series B warrants will expire on or before the later of 30 days following any final date assigned by the Food and Drug Administration as the Prescription Drug User Fee Act action date for vosaroxin (the “PDUFA date”) and September 4, 2015, but in no event later than March 4, 2016. The common stock and accompanying warrants have both been classified to stockholders’ equity (deficit) in the Company’s balance sheet.
	Controlled Equity Offerings
	In August 2011, the Company entered into a Controlled Equity OfferingSM sales agreement (the “Sales Agreement”), with Cantor Fitzgerald & Co. (“Cantor”), as agent and/or principal, pursuant to which the Company could issue and sell shares of its common stock having an aggregate gross sales price of up to $20.0 million. In April 2013, the Sales Agreement was amended to provide for an increase of $30.0 million in the aggregate gross sales price under the Sales Agreement. The Company will pay Cantor a commission of 3.0% of the gross proceeds from any common stock sold through the Sales Agreement, as amended.
	During the year ended December 31, 2014, the Company sold an aggregate of 5,113,876 shares of common stock under the Sales Agreement, as amended, at an average price of approximately $2.88 per share for gross proceeds of $14.7 million and net proceeds of $14.3 million, after deducting Cantor’s commission. As of December 31, 2014, $6.8 million of common stock remained available to be sold under this facility.
	In January and February 2015, the Company sold an aggregate of 1,579,124 shares of common stock under the Sales Agreement, as amended, at an average price of approximately $2.75 per share for gross proceeds of $4.3 million and net proceeds of $4.2 million, after deducting Cantor’s commission. As of February 27, 2015, $2.5 million of common stock remained available to be sold under the Sales Agreement, as amended, subject to certain conditions as specified in the agreement.
	2010 Offering
	In October 2010, the Company completed an underwritten offering, pursuant to which the Company issued an aggregate of 7,357,610 shares of common stock and warrants to purchase 3,678,798 shares of common stock, for aggregate gross proceeds of $15.5 million (the “2010 Offering”). Net proceeds from the sale were $14.2 million, after deducting underwriting discounts and offering expenses. The warrants have an exercise price of $2.52 per share, and expire in October 2015.
	The warrants have been classified as a derivative liability on the Company’s balance sheet due to potential cash settlement of the warrants on terms, which do not include a cash limit, and upon the occurrence of certain transactions, as specified in the warrant agreements. At each balance sheet date, the estimated fair value of the outstanding warrants is determined using the Black-Scholes model and recorded to the balance sheet, with the change in fair value recorded to other income (expense), net in the statements of operations and comprehensive loss. During the year ended December 31, 2014, warrants to purchase an aggregate of 179,427 shares of common stock that were issued in connection with the 2010 Offering were exercised, resulting in cash proceeds to the Company of $452,000. As of December 31, 2014, warrants to purchase an aggregate of 2,920,051 shares of common stock issued in connection with the 2010 Offering remained outstanding, with an estimated fair value of $3.5 million.
	Equity Incentive Plans
	The Company grants options to purchase shares of its common stock primarily to: (i) new employees, of which 25% of the shares subject to such options become exercisable on the first anniversary of the vesting commencement date, and 1/48th of the shares subject to such options become exercisable each month over the remainder of the four-year vesting period, (ii) existing employees, of which 1/48th of the shares subject to such options become exercisable each month following the date of grant over a four-year vesting period, (iii) new non-employee members of the board of directors, of which 50% of the shares subject to such options become exercisable on each of the first and second anniversary of the vesting commencement date, and (iv) continuing non-employee members of the board of directors, of which 1/24th of the shares subject to such options become exercisable each month following the date of grant over a two-year vesting period.
	On March 15, 2011, the Company’s Board of Directors adopted, and on June 3, 2011, the Company’s stockholders approved, the 2011 Equity Incentive Plan (the “2011 Plan”). The 2011 Plan is intended as the successor to and continuation of the Company’s 1998 Stock Plan, 2001 Stock Plan, 2005 Equity Incentive Award Plan and 2006 Employment Commencement Incentive Plan (collectively, the “Prior Plans”). No additional stock awards will be granted under the Prior Plans.
	The Company initially reserved a total of 6,041,856 shares of common stock for issuance under the 2011 Plan, which is the sum of (i) the 539,803 shares remaining available as of the Effective Date under the Prior Plans, (ii) an additional 4,400,000 new shares, and (iii) that portion of the 1,102,053 shares underlying stock options granted and currently outstanding under the Prior Plans that expire or terminate for any reason prior to exercise or settlement or that are forfeited because of the failure to meet a contingency or condition required to vest such shares.
	The number of shares of common stock available for issuance under the 2011 Plan automatically increases on January 1st of each year for a period of 10 years commencing on January 1, 2012 by an amount equal to: (i) 4.0% of the Company’s outstanding shares of common stock on December 31st of the preceding calendar year, or (ii) a lesser amount determined by the Board of Directors. On January 1, 2014 and 2013, in accordance with the above, the number of shares of common stock available for issuance under the 2011 Plan was increased by 2,173,764 and 2,062,609 shares, respectively.
	During the year ended December 31, 2014, options to purchase 3,840,500 shares of the Company’s common stock were granted under the 2011 Plan. As of December 31, 2014, there were 672,273 shares available for future grants under the 2011 Plan.
	Employee Stock Purchase Plans
	On March 5, 2011, the Company’s Board of Directors adopted, and on June 3, 2011, the Company’s stockholders approved, the 2011 Employee Stock Purchase Plan (the “2011 ESPP”). The 2011 ESPP is intended as the successor to the Company’s 2005 Employee Stock Purchase Plan, which was terminated on June 3, 2011.
	The 2011 ESPP permits eligible employees to purchase common stock at a discount through payroll deductions during defined offering periods. Eligible employees can purchase shares of the Company’s common stock at 85% of the lower of the fair market value of the common stock at (i) the beginning of a 12-month offering period, or (ii) at the end of one of the two related 6-month purchase periods. No participant in the 2011 ESPP may be issued or transferred shares of common stock valued at more than $25,000 per calendar year. The initial offering under the 2011 ESPP commenced on June 13, 2011 and ended on May 31, 2012. Subsequent 12-month offerings commenced or will commence on or around June 1st of each year.
	The Company initially reserved a total of 500,000 shares of common stock for issuance under the 2011 ESPP. The number of shares of common stock available for issuance under the 2011 ESPP automatically increases on January 1st of each year for a period of 10 years commencing on January 1, 2012 by an amount equal to: (i) 1.0% of the Company’s outstanding shares of common stock on December 31st of the preceding calendar year, or (ii) a lesser amount determined by the Board of Directors. On January 1, 2014 and 2013, in accordance with the above, the number of shares of common stock available for issuance under the 2011 ESPP was increased by 271,720 and nil shares, respectively.
	A total of 99,049 shares were issued under the 2011 ESPP during the year ended December 31, 2014. As of December 31, 2014, there were 431,672 shares available for future issuance under the ESPP.
	Warrants
	Warrants to purchase shares of the Company’s common stock outstanding as of December 31, 2014 were as follows (in thousands, except per share amounts):
				Exercise Price
	Date Issued	Shares		Per Share		Expiration
	Aug-05		14	$	54.6	August 2015
	Oct-10		2,920	$	2.52	October 2015
	Mar-14		4,650	$	12	Mar-16
	Apr-09		2,876	$	1.32	Apr-16
	Oct-09		1,438	$	1.32	Oct-16
	Total warrants outstanding and exercisable		11,898
	Reserved Shares
	Shares of the Company’s common stock reserved for future issuance as of December 31, 2014 were as follows (in thousands):
		Shares
		Available				Total
		for Future		Outstanding		Shares
		Grant		Securities		Reserved
	Warrants		—		11,898		11,898
	Stock option plans		672		10,584		11,256
	Employee stock purchase plan		432		—		432
	Total reserved shares of common stock		1,104		22,482		23,586

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	11. Stock-Based Compensation
	Overview
	Employee stock-based compensation expense is calculated based on the grant-date fair value of awards ultimately expected to vest, reduced for estimated forfeitures, and is recorded on a straight-line basis over the vesting period of the awards. Forfeitures are estimated at the time of grant, based on historical option cancellation information, and revised in subsequent periods if actual forfeitures differ from those estimates. The following table summarizes stock-based compensation expense related to the Company’s stock-based awards for the periods indicated (in thousands):
		Year ended December 31,
		2014			2013			2012
	Research and development	$	2,201		$	1,598		$	1,030
	General and administrative		3,681			1,983			1,372
	Employee stock-based compensation expense		5,882			3,581			2,402
	Non-employee stock-based compensation expense		337			304			322
	Total stock-based compensation expense	$	6,219		$	3,885		$	2,724
	Fair Value of Awards
	The Company determines the fair value of stock-based awards on the grant date using the Black-Scholes model, which is impacted by the Company’s stock price, as well as assumptions regarding a number of highly subjective variables. The following table summarizes the weighted-average assumptions used as inputs to the Black-Scholes model, and resulting weighted-average and total estimated grant date fair values of employee stock options granted during the periods indicated:
		Year Ended December 31,
		2014			2013			2012
	Assumptions:
	Expected term (years)		5.2			4.7			5.4
	Expected volatility		88.1	%		90	%		88.7	%
	Risk-free interest rate		1.7	%		1	%		1.1	%
	Expected dividend yield		0	%		0	%		0	%
	Fair value:
	Weighted-average estimated grant date fair value per	$	3.18		$	3.63		$	1.46
	share
	Options granted to employees (in thousands)		3,676			1,785			2,310
	Total estimated grant date fair value (in thousands)	$	11,704		$	6,472		$	3,377
	The estimated fair value of stock options that vested in the years ended December 31, 2014, 2013 and 2012, was $2.6 million, $3.4 million and $2.1 million, respectively. The Company based its assumptions for the expected term on historical cancellation and exercise data, and the contractual term and vesting terms of the awards. Expected volatility is based on historical volatility of the Company’s common stock, as well as that for a mature peer group of companies in the same industry. The Company does not anticipate paying any cash dividends in the foreseeable future, and therefore uses an expected dividend yield of zero.
	Option Plan Activity
	The following table summarizes stock option activity for the Company’s stock option plans in the periods presented (in thousands, except per share amounts):
					Weighted			Weighted
					Average			Average
		Number			Exercise			Remaining			Aggregate
		of			Price Per			Contractual			Intrinsic
		Shares			Share			Term (Years)			Value
	Outstanding as of December 31, 2013		7,611		$	3.61
	Options granted		3,840		$	4.54
	Options exercised		(565	)	$	2.17
	Options forfeited or expired		(302	)	$	7.13
	Outstanding as of December 31, 2014		10,584		$	3.93			7.63		$	3,885
	Vested and expected to vest as of December 31, 2014		10,584		$	3.93			7.63		$	3,885
	Exercisable as of December 31, 2014		5,701		$	3.86			6.57		$	2,075
	The aggregate intrinsic value in the table above represents the total pre-tax intrinsic value (i.e., the difference between the Company’s closing stock price on the last trading day of the period and the exercise price, multiplied by the number of in-the-money options) that would have been received by option holders if they had exercised all their options on December 31, 2014.
	The intrinsic value of options exercised during the years ended December 31, 2014, 2013 and 2012 was $2.7 million, $0.3 million and $0.2 million, respectively. As the Company believes it is more likely than not that no stock option related tax benefits will be realized, the Company does not record any net tax benefits related to exercised options.
	Total estimated unrecognized stock-based compensation cost related to unvested stock options was $12.2 million as of December 31, 2014, which is expected to be recognized over the respective vesting terms of each award. The weighted average term of the unrecognized stock-based compensation expense is 2.6 years.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes
	Loss before the provision for income taxes consisted of the following (in thousands):
		Year Ended December 31,
		2014			2013			2012
	U.S. operations	$	(32,696	)	$	(29,963	)	$	(43,951	)
	Foreign operations		(10,306	)		(4,635	)		—
	Loss before provision for income taxes	$	(43,002	)	$	(34,598	)	$	(43,951	)
	No provision for income taxes was recorded in the periods presented due to tax losses incurred in each period. The income tax provision differs from the amount computed by applying the statutory income tax rate of 34% to pre-tax loss as follows (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Tax at statutory rate	$	(14,620	)	$	(11,763	)	$	(14,943	)
	Current year net operating losses and temporary differences		14,104			12,457			5,351
	for which no tax benefit is recognized
	Foreign tax rate differential		3,504			1,499			—
	Deferred revenue		(1,934	)		(2,706	)		6,672
	Change in fair value of warrant liability		(1,313	)		(16	)		2,570
	Other permanent differences		259			529			350
	Provision for income taxes	$	—		$	—		$	—
	Deferred income taxes reflect the net tax effects of loss and credit carry-forwards and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets for federal and state income taxes are as follows (in thousands):
		December 31,
		2014			2013
	Deferred tax assets:
	Federal and state net operating loss carry-forwards	$	138,066		$	123,490
	Federal and state research credit carry-forwards		12,964			12,064
	Capitalized research costs		5,199			5,119
	Deferred revenue		2,394			4,668
	Stock-based compensation		4,358			3,212
	Property and equipment		129			133
	Accrued liabilities		481			341
	Gross deferred tax assets		163,591			149,027
	Valuation allowance		(163,591	)		(149,027	)
	Net deferred tax assets	$	—		$	—
	Realization of the deferred tax assets is dependent upon future taxable income, if any, the amount and timing of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The net valuation allowance increased by approximately $14.6 million, $12.6 million and $13.7 million during the years ended December 31, 2014, 2013 and 2012, respectively.
	As of December 31, 2014, the Company had federal net operating loss carry-forwards of $364.5 million and federal research and development tax credit carry-forwards of $8.1 million. If not utilized, the federal net operating loss and tax credit carry-forwards will expire at various dates beginning in 2018. As of December 31, 2014, the Company had state net operating loss carry-forwards of $235.8 million, which begin to expire in 2015, and state research and development tax credit carry-forwards of $7.2 million, which do not expire.
	Utilization of these net operating loss and tax credits carry-forwards may be subject to a substantial annual limitation due to the ownership change rules under Section 382 of the Internal Revenue Code of 1986, as amended (the “Code”). The limitations are applicable if an “ownership change,” as defined in the Code, is deemed to have occurred or occurs in the future. The annual limitation may result in the expiration of net operating loss and credit carry-forwards before they can be utilized.
	The Company recognizes the financial statement effect of tax positions when it is more likely than not that the tax positions will be sustained upon examination by the appropriate taxing authorities. As of December 31, 2014 and 2013, the Company had no unrecognized tax positions.
	The Company files U.S. federal and California tax returns.  The Company’s wholly owned subsidiaries, Sunesis Europe Limited and Sunesis Pharmaceuticals (Bermuda) Ltd., are currently not required to file tax returns. To date, neither the Company nor any of its subsidiaries have been audited by the Internal Revenue Service, any state income tax authority or tax authority in the related jurisdictions. Due to net operating loss carry-forwards, substantially all of the Company’s tax years remain open to federal tax examination.

Guarantees_and_Indemnification

Guarantees and Indemnification	12 Months Ended
	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Guarantees and Indemnification	13. Guarantees and Indemnification
	As permitted under Delaware law and in accordance with the Company’s Bylaws, the Company indemnifies its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity. The indemnification agreements with the Company’s officers and directors terminate upon termination of their employment, but the termination does not affect claims for indemnification relating to events occurring prior to the effective date of termination. The maximum amount of potential future indemnification is unlimited; however, the Company’s officer and director insurance policy reduces the Company’s exposure and may enable the Company to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification agreements is minimal. In addition, in the ordinary course of business the Company enters into agreements, such as licensing agreements, clinical trial agreements and certain services agreements, containing standard indemnifications provisions. The Company believes that the likelihood of an adverse judgment related to such indemnification provisions is remote. Accordingly, the Company has not recorded any liabilities for any of these agreements as of December 31, 2014.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events
	On February 27, 2015, the Company entered into a third amendment (the “Amendment”), to the Loan Agreement with the Lenders. The Amendment modifies the loan repayment terms to be interest-only from March 1, 2015 to February 1, 2016, followed by eight equal monthly payments of principal and interest through the new maturity date of October 1, 2016. In addition, the final payment will be increased from $937,500 (3.75%) to $1,162,500 (4.65%) of the total loan facility, and will become due on the new maturity date, or such earlier date specified in the Loan Agreement. If the Company repays all or a portion of the loan prior to February 29, 2016 as part of a refinancing with another lender, a prepayment fee equal to 2% of the then outstanding principal balance will be due to the Lenders. As a result of the Amendment, the Lenders were issued five-year warrants to purchase an aggregate of up to 61,467 shares of the Company’s common stock at a per share exercise price of $2.22.
	In January and February 2015, the Company sold an aggregate of 1,579,124 shares of common stock under the Sales Agreement, as amended, at an average price of approximately $2.75 per share for gross proceeds of $4.3 million and net proceeds of $4.2 million, after deducting Cantor’s commission. See Note 10 for further details.
	In January 2015, the lease for the Company’s facility at 395 Oyster Point Boulevard in South San Francisco, California was amended to extend the expiration date to December 31, 2015. See Note 9 for further details.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data
	15. Selected Quarterly Financial Data (unaudited, and in thousands, except per share amounts)
	The following table sets forth the Company’s unaudited consolidated financial results for the last eight fiscal quarters.
		Three Months Ended
		Mar. 31,			June 30,			Sep. 30,			Dec. 31,			Mar. 31,			June 30,			Sep. 30,			Dec. 31,
		2014			2014			2014			2014			2013			2013			2013			2013
	Revenue	$	1,995		$	1,989		$	854		$	896		$	1,989		$	1,989		$	1,989		$	1,989
	Net loss:
	Basic	$	(14,573	)	$	(11,781	)	$	(15,325	)	$	(1,323	)	$	(11,624	)	$	(8,190	)	$	(7,607	)	$	(7,177	)
	Diluted	$	(14,573	)	$	(12,114	)	$	(15,325	)	$	(1,323	)	$	(11,624	)	$	(9,336	)	$	(8,329	)	$	(8,257	)
	Shares used in computing net loss per
	common share:
	Basic		56,313			60,246			60,549			63,041			51,587			51,630			51,698			54,060
	Diluted		56,313			61,895			60,549			63,041			51,587			53,268			53,271			55,573
	Net loss per common share:
	Basic	$	(0.26	)	$	(0.20	)	$	(0.25	)	$	(0.02	)	$	(0.23	)	$	(0.16	)	$	(0.15	)	$	(0.13	)
	Diluted	$	(0.26	)	$	(0.20	)	$	(0.25	)	$	(0.02	)	$	(0.23	)	$	(0.18	)	$	(0.16	)	$	(0.15	)

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation
	The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”).
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), that will supersede most existing revenue recognition guidance under US GAAP. The core principle of the guidance is that an entity should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. Entities can choose to apply the standard using either the full retrospective approach or a modified retrospective approach. Entities electing the full retrospective adoption will apply the standard to each period presented in the financial statements. This means that entities will have to apply the new guidance as if it had been in effect since the inception of all its contracts with customers presented in the financial statements. Entities that elect the modified retrospective approach will apply the guidance retrospectively only to the most current period presented in the financial statements. This means that entities will have to recognize the cumulative effect of initially applying the new standard as an adjustment to the opening balance of retained earnings at the date of initial application. The new revenue standard will be applied to contracts that are in progress at the date of initial application. The standard will be effective for annual and interim periods beginning after December 15, 2016. The Company has yet to evaluate which adoption method it plans to use or the potential effect of the new standard on its consolidated financial statements.
	In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”), which will require a reporting entity to evaluate, at each annual and interim reporting period, whether there are conditions or events that raise substantial doubt about the reporting entity’s ability to continue as a going concern within one year after the date the financial statements are issued and provide related disclosures. The standard will be effective for annual and interim periods beginning after December 15, 2016, with early adoption permitted. The Company has yet to evaluate the potential effect of the new standard on its consolidated financial statements.
Principles of Consolidation	Principles of Consolidation
Segment Reporting	Segment Reporting
	Management has determined that the Company operates as a single reportable segment.
Significant Estimates and Judgments	Significant Estimates and Judgments
Cash Equivalents and Marketable Securities	Cash Equivalents and Marketable Securities
	The Company considers all highly liquid securities with original maturities of three months or less from the date of purchase to be cash equivalents, which generally consist of money market funds and corporate debt securities. Marketable securities consist of securities with original maturities of greater than three months, which may include U.S. and European government obligations and corporate debt securities.
	Management determines the appropriate classification of securities at the time of purchase. The Company generally classifies its entire investment portfolio as available-for-sale. The Company views its available-for-sale portfolio as available for use in current operations. Accordingly, the Company classifies all investments as short-term, even though the stated maturity may be more than one year from the current balance sheet date. Available-for-sale securities are carried at fair value, with unrealized gains and losses reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity (deficit).
	The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in other income (expense), net in the statements of operations and comprehensive loss. Realized gains and losses and declines in value judged to be other-than-temporary on available-for-sale securities, if any, are also recorded to other income (expense), net. The cost of securities sold is based on the specific-identification method.
	Invoices for certain services provided to the Company are denominated in foreign currencies. To manage the risk of future movements in foreign exchange rates that would affect such amounts, the Company may purchase certain European currencies or highly-rated investments denominated in those currencies, subject to similar criteria as for other investments defined in the Company’s investment policy. There is no guarantee that the related gains and losses will substantially offset each other, and the Company may be subject to significant exchange gains or losses as currencies fluctuate from quarter to quarter. To date, the Company has purchased Euros and Euro-denominated obligations of foreign governments and corporate debt. As of December 31, 2014 and December 31, 2013, the Company held investments denominated in Euros with an aggregate fair value of $0 and $2.6 million, respectively. Any cash, cash equivalent and short-term investment balances denominated in foreign currencies are recorded at their fair value based on the current exchange rate as of each balance sheet date. The resulting exchange gains or losses and those from amounts payable for services originally denominated in foreign currencies are both recorded in other income (expense), net in the statements of operations and comprehensive loss.
Fair Value Measurements	Fair Value Measurements
	The Company measures cash equivalents, marketable securities and warrant liabilities at fair value on a recurring basis using the following hierarchy to prioritize valuation inputs, in accordance with applicable GAAP:
	Level 1 -	quoted prices (unadjusted) in active markets for identical assets and liabilities that can be accessed at the measurement date
	Level 2 -	inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly
	Level 3 -	unobservable inputs
	The Company’s Level 2 valuations of marketable securities are generally derived from independent pricing services based upon quoted prices in active markets for similar securities, with prices adjusted for yield and number of days to maturity, or based on industry models using data inputs, such as interest rates and prices that can be directly observed or corroborated in active markets.
	The fair value of the Company’s liability for warrants issued in connection with an underwritten offering completed in October 2010 (the “2010 Offering”) is determined using the Black-Scholes model, which requires inputs such as the expected term of the warrants, share price volatility, expected dividend yield and risk-free interest rate. As some of these inputs are unobservable, and require significant analysis and judgment to measure, these variables are classified as Level 3.
	The carrying amounts of the Company’s financial instruments, including cash, prepayments, accounts payable, accrued liabilities, deferred revenue and notes payable approximated their fair value as of December 31, 2014 and December 31, 2013.
Property and Equipment	Property and Equipment
	Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the term of the lease.
Accounting for Royalty Agreement	Accounting for Royalty Agreement
	The payment of $25.0 million by RPI under the Royalty Agreement (see Note 6) is non-refundable, and no revenue participation right payments will be made unless vosaroxin is commercialized. Accordingly, the payment received from RPI is being accounted for as a payment for the Company to use commercially reasonable efforts to commercialize vosaroxin. Therefore, the amount is to be deferred and recognized as revenue over the projected performance period under the agreement. The payment, less $3.1 million representing the fair value of the warrants granted under the arrangement, was initially classified as deferred revenue and is being amortized to revenue over the related performance period. The fair value of the warrants was recorded to additional paid-in capital.
Accounting for Notes Payable	Accounting for Notes Payable
	The accounting for certain fees and expenses related to the Loan Agreement (see Note 8) is as follows. The facility fee is being accounted for as a debt discount and classified within notes payable on the Company’s balance sheet. The fair value of the warrants issued in connection with the Loan Agreement have been recorded as a debt discount within notes payable and an increase to additional paid-in capital on the Company’s balance sheet. The debt discount is being amortized as interest expense over the term of the loan using the effective interest method. The final payment is being accreted as interest expense over the term of the loans using the effective interest method. The legal fees are being accounted for as deferred debt issuance costs within assets on the Company’s balance sheet and are being amortized as other income (expense), net over the term of the loans using the effective interest method.
Accounting for Equity Financing	Accounting for Equity Financing
	In October 2010, the Company completed the 2010 Offering (see Note 10), in which the Company sold its common stock and warrants to purchase its common stock for aggregate gross proceeds of $15.5 million. Due to the potential for the warrants to be settled in cash upon the occurrence of certain transactions specified in the warrant agreements, the warrants are being accounted for as a derivative liability as opposed to permanent equity. Outstanding warrants under this arrangement are revalued to their fair value each period end, with the change in fair value recorded to other income (expense), net in the statements of operations and comprehensive loss.
Revenue Recognition	Revenue Recognition
	Revenue arrangements with multiple deliverables are accounted for in accordance with the Financial Accounting Standards Board Accounting Standards Codification, Subtopic 605-25, Multiple-Element Arrangements (“ASC 605-25”). Under ASC 605-25, revenue arrangements with multiple deliverables are divided into separate units of accounting based on whether certain criteria are met, including whether the delivered item has stand-alone value to the customer. Consideration is allocated among the separate units of accounting based on their respective fair value, and the applicable revenue recognition is applied to each of the separate units.
	Non-refundable fees where the Company has no continuing performance obligations are recognized as revenues when collection is reasonably assured. In situations where continuing performance obligations exist, non-refundable fees are deferred and recognized ratably over the projected performance period.
	Milestone payments from license or collaboration agreements which are substantive and at risk at the time the agreement is executed are recognized upon completion of the applicable milestone event. Royalty revenues, if any, will be recognized based on reported product sales by third-party licensees. Research funding from any future agreement will be recognized as the related research services are performed.
Research and Development	Research and Development
	Research and development expense consists primarily of: (a) clinical trial costs, which include payments for work performed by contract research organizations (“CROs”), clinical trial sites, labs and other clinical service providers, and for drug packaging, storage and distribution; (b) drug manufacturing costs, which include costs for producing drug substance and drug product, and for stability and other testing; (c) personnel costs for related permanent and temporary employees; (d) other outside services and consulting costs; and (e) payments under license agreements. All research and development costs are expensed as they are incurred.
Clinical Trial Accounting	Clinical Trial Accounting
	The Company records accruals for estimated clinical trial costs, which include payments for work performed by CROs and participating clinical trial sites. These costs are generally a significant component of research and development expense. Costs incurred for setting up clinical trial sites for participation in trials are generally non-refundable, and are expensed as incurred, with any refundable advances related to enrollment of the first patient recorded as prepayments and assessed for recoverability on a quarterly basis. Costs related to patient enrollment are accrued as patients progress through the clinical trial, including amortization of any first-patient prepayments. This amortization generally matches when the related services are rendered, however, these cost estimates may or may not match the actual costs incurred by the CROs or clinical trial sites, and if the Company has incomplete or inaccurate information, the clinical trial accruals may not be accurate. The difference between accrued expenses based on the Company’s estimates and actual expenses have not been significant to date.
Stock-Based Compensation	Stock-Based Compensation
	The Company grants options to purchase common stock to its employees, directors and consultants under its stock option plans. Under the Company’s Employee Stock Purchase Plan, eligible employees can also purchase shares of the Company’s common stock at 85% of the lower of the fair market value of the Company’s common stock at the beginning of a 12-month offering period or at the end of one of the two related six-month purchase periods.
	The Company values these share-based awards using the Black-Scholes option valuation model (the “Black-Scholes model”). The determination of fair value of share-based payment awards on the date of grant using the Black-Scholes model is affected by the Company’s stock price as well as assumptions regarding a number of highly complex and subjective variables. These variables include, but are not limited to, the expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors and related estimated forfeitures.
Foreign Currency	Foreign Currency
	Transactions that are denominated in a foreign currency are translated into U.S. dollars at the current exchange rate on the transaction date. Any foreign currency-denominated monetary assets and liabilities are subsequently remeasured at current exchange rates as of each balance sheet date, with gains or losses on foreign exchange recognized in other income (expense), net in the statements of operations and comprehensive loss.
Income Taxes	Income Taxes
	The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the differences between the tax basis of assets and liabilities and their basis for financial reporting. Deferred tax assets or liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which temporary differences are expected to be recovered or settled. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to recognize interest charges and penalties in other income (expense), net in the statements of operations and comprehensive loss.

Loss_per_Common_Share_Tables

Loss per Common Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Computation of Basic and Diluted Loss per Common Share	The following table sets forth the computation of basic and diluted loss per common share for the periods presented (in thousands, except per share amounts):
		Year Ended December 31,
		2014			2013			2012
	Numerator:
	Net loss—basic	$	(43,002	)	$	(34,598	)	$	(43,951	)
	Adjustment for change in fair value of warrant liability		(3,892	)		—			—
	Net loss—diluted	$	(46,894	)	$	(34,598	)	$	(43,951	)
	Denominator:
	Weighted-average common shares outstanding—basic		60,057			52,249			48,146
	Dilutive effect of warrants		1,453			—			—
	Weighted-average common shares outstanding—diluted		61,510			52,249			48,146
	Net loss per common share:
	Basic	$	(0.72	)	$	(0.66	)	$	(0.91	)
	Diluted	$	(0.76	)	$	(0.66	)	$	(0.91	)
Schedule of Potential Common Shares Issuable Pursuant to Outstanding Securities Excluded from Computation of Diluted Loss per Common Share	The following table represents the potential common shares issuable pursuant to outstanding securities as of the related period end dates that were excluded from the computation of diluted loss per common share because their inclusion would have had an anti-dilutive effect (in thousands):
		As of December 31,
		2014			2013			2012
	Warrants to purchase shares of common stock		8,978			9,978			10,359
	Options to purchase shares of common stock		10,584			7,611			6,288
	Outstanding securities not included in calculations		19,562			17,589			16,647

Financial_Instruments_Tables

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value of Company's Financial Assets Measured on Recurring Basis	The following tables summarize the estimated fair value of the Company’s financial assets measured on a recurring basis as of the dates indicated, which were comprised solely of available-for-sale marketable securities with remaining contractual maturities of one year or less (in thousands):
								Gross		Gross
		Valuation		Amortized				Unrealized		Unrealized			Estimated Fair
	December 31, 2014	Input Level		Cost				Gains		Losses			Value
	Money market funds	Level 1		$	9,287			$	—	$	—		$	9,287
	U.S. certificates of deposit	Level 1			6,360				—		—			6,360
	U.S. corporate debt obligations	Level 2			11,789				—		(7	)		11,782
	U.S. commercial paper	Level 2			2,898				—		—			2,898
	Total available-for-sale securities				30,334				—		(7	)		30,327
	Less amounts classified as cash equivalents				(9,532	)			—		—			(9,532	)
	Amounts classified as marketable securities			$	20,802			$	—	$	(7	)	$	20,795
								Gross		Gross
		Valuation		Amortized				Unrealized		Unrealized			Estimated Fair
	December 31, 2013	Input Level		Cost				Gains		Losses			Value
	Money market funds	Level 1		$	6,282			$	—	$	—		$	6,282
	U.S. corporate debt obligations	Level 2			13,509				—		(4	)		13,505
	U.S. commercial paper	Level 2			8,396				3		—			8,399
	Foreign corporate debt obligations	Level 2			2,571				—		(2	)		2,569
	Total available-for-sale securities				30,758				3		(6	)		30,755
	Less amounts classified as cash equivalents				(6,583	)			—		—			(6,583	)
	Amounts classified as marketable securities			$	24,175			$	3	$	(6	)	$	24,172
Summary of Available-for-Sale Securities in Unrealized Loss Position	The following table summarizes the available-for-sale securities that were in an unrealized loss position as of December 31, 2014, each having been in such a position for less than 12 months, and none deemed to be other-than-temporarily impaired (in thousands):
		Gross
		Unrealized				Estimated Fair
	December 31, 2014	Losses				Value
	U.S. corporate debt obligations	$	7			$	11,782
	Total available-for-sale securities in an unrealized loss	$	7			$	11,782
	position
Summary of Assumptions and Estimated Fair Value of Company's Financial Liabilities Measured on Recurring Basis	The following table summarizes the inputs and assumptions and estimated fair value of the Company’s financial liabilities measured on a recurring basis as of the dates indicated, which were comprised solely of a liability for warrants issued in connection with an underwritten equity offering completed in 2010 (see Note 10):
		December 31,				December 31,
		2014				2013
	Inputs and assumptions:
	Fair market value of Company’s common stock	$	2.55			$	4.74
	Exercise price	$	2.52			$	2.52
	Expected term (years)		0.8				1.8
	Expected volatility		144.9	%			60.8	%
	Risk-free interest rate		0.2	%			0.3	%
	Expected dividend yield		0	%			0	%
	Fair value:
	Estimated fair value per warrant share	$	1.21			$	2.56
	Shares underlying outstanding warrants classified as		2,920				3,099
	liabilities (in thousands)
	Total estimated fair value of outstanding warrants	$	3,543			$	7,931
	(in thousands)
Summary of Changes in Fair Value of Company's Level 3 Financial Liabilities	The following table summarizes the changes in the fair value of the Company’s Level 3 financial liabilities for the periods indicated (in thousands):
		Warrant
		Liability
	Balance as of December 31, 2012	$	8,070
	Change in fair value of warrant liability		(96	)
	Exercise of warrants		(43	)
	Balance as of December 31, 2013		7,931
	Change in fair value of warrant liability		(3,892	)
	Exercise of warrants		(496	)
	Balance as of December 31, 2014	$	3,543

Other_Accrued_Liabilities_Tabl

Other Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Payables And Accruals [Abstract]
Summary of Other Accrued Liabilities	Other accrued liabilities as of December 31 were as follows (in thousands):
		2014		2013
	Accrued outside services	$	2,656	$	1,249
	Accrued professional services		355		263
	Other accruals		76		133
	Total other accrued liabilities	$	3,087	$	1,645

Notes_Payable_Tables

Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Summary of Future Minimum Payments Under Loan Agreement	Aggregate future minimum payments due under the Loan Facility as of December 31, 2014 were as follows (in thousands):
	Year ending December 31,	Total
	2015	$	8,814
	Total minimum payments		8,814
	Less amount representing interest		(352	)
	Notes payable, gross		8,462
	Unamortized discount on notes payable		(84	)
	Accretion of final payment		879
	Notes payable, balance		9,257
	Less current portion of notes payable		(9,257	)
	Non-current portion of notes payable	$	—

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Aggregate Non-Cancelable Future Minimum Rental Payments under Operating Lease	Aggregate non-cancelable future minimum rental payments under the operating lease as of December 31, 2014 were as follows (in thousands):
	Year Ending December 31,	Payments
	2015	$	247
	Total rental payments	$	247

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Schedule of Warrants to Purchase Shares of Company's Common Stock	Warrants to purchase shares of the Company’s common stock outstanding as of December 31, 2014 were as follows (in thousands, except per share amounts):
				Exercise Price
	Date Issued	Shares		Per Share		Expiration
	Aug-05		14	$	54.6	August 2015
	Oct-10		2,920	$	2.52	October 2015
	Mar-14		4,650	$	12	Mar-16
	Apr-09		2,876	$	1.32	Apr-16
	Oct-09		1,438	$	1.32	Oct-16
	Total warrants outstanding and exercisable		11,898
Shares of Common Stock Reserved for Future Issuance	Shares of the Company’s common stock reserved for future issuance as of December 31, 2014 were as follows (in thousands):
		Shares
		Available				Total
		for Future		Outstanding		Shares
		Grant		Securities		Reserved
	Warrants		—		11,898		11,898
	Stock option plans		672		10,584		11,256
	Employee stock purchase plan		432		—		432
	Total reserved shares of common stock		1,104		22,482		23,586

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock-Based Compensation Expense Related to Company's Stock-Based Awards	The following table summarizes stock-based compensation expense related to the Company’s stock-based awards for the periods indicated (in thousands):
		Year ended December 31,
		2014			2013			2012
	Research and development	$	2,201		$	1,598		$	1,030
	General and administrative		3,681			1,983			1,372
	Employee stock-based compensation expense		5,882			3,581			2,402
	Non-employee stock-based compensation expense		337			304			322
	Total stock-based compensation expense	$	6,219		$	3,885		$	2,724
Summary of Weighted-Average and Total Estimated Grant Date Fair Values of Employee Stock Options Granted	The following table summarizes the weighted-average assumptions used as inputs to the Black-Scholes model, and resulting weighted-average and total estimated grant date fair values of employee stock options granted during the periods indicated:
		Year Ended December 31,
		2014			2013			2012
	Assumptions:
	Expected term (years)		5.2			4.7			5.4
	Expected volatility		88.1	%		90	%		88.7	%
	Risk-free interest rate		1.7	%		1	%		1.1	%
	Expected dividend yield		0	%		0	%		0	%
	Fair value:
	Weighted-average estimated grant date fair value per	$	3.18		$	3.63		$	1.46
	share
	Options granted to employees (in thousands)		3,676			1,785			2,310
	Total estimated grant date fair value (in thousands)	$	11,704		$	6,472		$	3,377
Summary of Stock Option Activity for Company's Stock Option Plans	The following table summarizes stock option activity for the Company’s stock option plans in the periods presented (in thousands, except per share amounts):
					Weighted			Weighted
					Average			Average
		Number			Exercise			Remaining			Aggregate
		of			Price Per			Contractual			Intrinsic
		Shares			Share			Term (Years)			Value
	Outstanding as of December 31, 2013		7,611		$	3.61
	Options granted		3,840		$	4.54
	Options exercised		(565	)	$	2.17
	Options forfeited or expired		(302	)	$	7.13
	Outstanding as of December 31, 2014		10,584		$	3.93			7.63		$	3,885
	Vested and expected to vest as of December 31, 2014		10,584		$	3.93			7.63		$	3,885
	Exercisable as of December 31, 2014		5,701		$	3.86			6.57		$	2,075

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Loss before Provision for Income Taxes	Loss before the provision for income taxes consisted of the following (in thousands):
		Year Ended December 31,
		2014			2013			2012
	U.S. operations	$	(32,696	)	$	(29,963	)	$	(43,951	)
	Foreign operations		(10,306	)		(4,635	)		—
	Loss before provision for income taxes	$	(43,002	)	$	(34,598	)	$	(43,951	)
Income Tax Provision Amount Computed by Applying Statutory Income Tax Rate	The income tax provision differs from the amount computed by applying the statutory income tax rate of 34% to pre-tax loss as follows (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Tax at statutory rate	$	(14,620	)	$	(11,763	)	$	(14,943	)
	Current year net operating losses and temporary differences		14,104			12,457			5,351
	for which no tax benefit is recognized
	Foreign tax rate differential		3,504			1,499			—
	Deferred revenue		(1,934	)		(2,706	)		6,672
	Change in fair value of warrant liability		(1,313	)		(16	)		2,570
	Other permanent differences		259			529			350
	Provision for income taxes	$	—		$	—		$	—
Significant Components of Deferred Tax Assets	Significant components of the Company’s deferred tax assets for federal and state income taxes are as follows (in thousands):
		December 31,
		2014			2013
	Deferred tax assets:
	Federal and state net operating loss carry-forwards	$	138,066		$	123,490
	Federal and state research credit carry-forwards		12,964			12,064
	Capitalized research costs		5,199			5,119
	Deferred revenue		2,394			4,668
	Stock-based compensation		4,358			3,212
	Property and equipment		129			133
	Accrued liabilities		481			341
	Gross deferred tax assets		163,591			149,027
	Valuation allowance		(163,591	)		(149,027	)
	Net deferred tax assets	$	—		$	—

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Data	The following table sets forth the Company’s unaudited consolidated financial results for the last eight fiscal quarters.
		Three Months Ended
		Mar. 31,			June 30,			Sep. 30,			Dec. 31,			Mar. 31,			June 30,			Sep. 30,			Dec. 31,
		2014			2014			2014			2014			2013			2013			2013			2013
	Revenue	$	1,995		$	1,989		$	854		$	896		$	1,989		$	1,989		$	1,989		$	1,989
	Net loss:
	Basic	$	(14,573	)	$	(11,781	)	$	(15,325	)	$	(1,323	)	$	(11,624	)	$	(8,190	)	$	(7,607	)	$	(7,177	)
	Diluted	$	(14,573	)	$	(12,114	)	$	(15,325	)	$	(1,323	)	$	(11,624	)	$	(9,336	)	$	(8,329	)	$	(8,257	)
	Shares used in computing net loss per
	common share:
	Basic		56,313			60,246			60,549			63,041			51,587			51,630			51,698			54,060
	Diluted		56,313			61,895			60,549			63,041			51,587			53,268			53,271			55,573
	Net loss per common share:
	Basic	$	(0.26	)	$	(0.20	)	$	(0.25	)	$	(0.02	)	$	(0.23	)	$	(0.16	)	$	(0.15	)	$	(0.13	)
	Diluted	$	(0.26	)	$	(0.20	)	$	(0.25	)	$	(0.02	)	$	(0.23	)	$	(0.18	)	$	(0.16	)	$	(0.15	)

Company_Overview_Additional_In

Company Overview - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Date of incorporation	10-Feb-98
Cash, cash equivalents and marketable securities	$43,000,000
Accumulated deficit	($522,697,000)	($479,695,000)
Maturity limits period	24 months
Dollars weighted average maturity limit period	12 months

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended
In Millions, unless otherwise specified	Mar. 04, 2014	Oct. 31, 2010	Dec. 31, 2014	Sep. 30, 2012	Dec. 31, 2013
			Segment
Significant Accounting Policies [Line Items]
Number of reportable segment			1
Fair value of investments denominated in Euros			$0		$2.60
Proceeds from issuance of common stock and warrants in offering gross	43	15.5
Common stock offering period			At the beginning of a 12-month offering period or at the end of one of the two related six-month purchase periods.
Employee Stock Purchase Plan [Member]
Significant Accounting Policies [Line Items]
Purchase price of a share as a percentage of fair market value			85.00%
Royalty Agreement [Member]
Significant Accounting Policies [Line Items]
Revenue participation right payments			25	25
Fair value of warrants issued in connection with participation agreement			$3.10	$3.10
Minimum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of assets			3 years
Maximum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of assets			5 years

Loss_per_Common_Share_Computat

Loss per Common Share - Computation of Basic and Diluted Loss per Common 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—basic	($1,323)	($15,325)	($11,781)	($14,573)	($7,177)	($7,607)	($8,190)	($11,624)	($43,002)	($34,598)	($43,951)
Adjustment for change in fair value of warrant liability									-3,892
Net loss—diluted	($1,323)	($15,325)	($12,114)	($14,573)	($8,257)	($8,329)	($9,336)	($11,624)	($46,894)	($34,598)	($43,951)
Denominator:
Weighted-average common shares outstanding—basic	63,041	60,549	60,246	56,313	54,060	51,698	51,630	51,587	60,057	52,249	48,146
Dilutive effect of warrants									1,453
Weighted-average common shares outstanding—diluted	63,041	60,549	61,895	56,313	55,573	53,271	53,268	51,587	61,510	52,249	48,146
Net loss per common share:
Basic	($0.02)	($0.25)	($0.20)	($0.26)	($0.13)	($0.15)	($0.16)	($0.23)	($0.72)	($0.66)	($0.91)
Diluted	($0.02)	($0.25)	($0.20)	($0.26)	($0.15)	($0.16)	($0.18)	($0.23)	($0.76)	($0.66)	($0.91)

Loss_per_Common_Share_Schedule

Loss per Common Share - Schedule of Potential Common Shares Issuable Pursuant to Outstanding Securities Excluded from Computation of Diluted Loss per Common Share (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]
Outstanding securities not included in calculations	19,562	17,589	16,647
Warrants to purchase shares of common stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	8,978	9,978	10,359
Options to purchase shares of common stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding securities not included in calculations	10,584	7,611	6,288

Financial_Instruments_Fair_Val

Financial Instruments - Fair Value of Company's Financial Assets Measured on Recurring Basis (Detail) (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]
Available-for-sale securities, Amortized Cost	$30,334	$30,758
Available-for-sale securities, Gross Unrealized Gains		3
Available-for-sale securities, Gross Unrealized Losses	-7	-6
Available-for-sale securities, Estimated Fair Value	30,327	30,755
Less amounts classified as cash equivalents, Amortized Cost	-9,532	-6,583
Amounts classified as marketable securities, Amortized Cost	20,802	24,175
Amounts classified as marketable securities, Gross Unrealized Gains		3
Amounts classified as marketable securities, Gross Unrealized Losses	-7	-6
Less amounts classified as cash equivalents, Estimated Fair Value	-9,532	-6,583
Amounts classified as marketable securities, Estimated Fair Value	20,795	24,172
Level 1 [Member] | Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	9,287	6,282
Available-for-sale securities, Estimated Fair Value	9,287	6,282
Level 1 [Member] | U.S. certificates of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	6,360
Available-for-sale securities, Estimated Fair Value	6,360
Level 2 [Member] | U.S. corporate debt obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	11,789	13,509
Available-for-sale securities, Gross Unrealized Losses	-7	-4
Available-for-sale securities, Estimated Fair Value	11,782	13,505
Level 2 [Member] | U.S. commercial paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost	2,898	8,396
Available-for-sale securities, Gross Unrealized Gains		3
Available-for-sale securities, Estimated Fair Value	2,898	8,399
Level 2 [Member] | Foreign corporate debt obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities, Amortized Cost		2,571
Available-for-sale securities, Gross Unrealized Losses		-2
Available-for-sale securities, Estimated Fair Value		$2,569

Financial_Instruments_Summary_

Financial Instruments - Summary of Available-for-Sale Securities in Unrealized Loss Position (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gross Unrealized Losses	$7
Estimated Fair Value	11,782
U.S. corporate debt obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gross Unrealized Losses	7
Estimated Fair Value	$11,782

Financial_Instruments_Addition

Financial Instruments - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Sales of available-for-sale securities	$0	$0	$0
2010 Offering [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants exercised for cash, shares	179,427
Exercise of warrants for cash	$452,000

Financial_Instruments_Summary_1

Financial Instruments - Summary of Assumptions and Estimated Fair Value of Company's Financial Liabilities Measured on Recurring Basis (Detail) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Inputs and assumptions:
Fair market value of Company’s common stock	$2.55	$4.74
Exercise price	$2.52	$2.52
Expected term (years)	9 months 18 days	1 year 9 months 18 days
Expected volatility	144.90%	60.80%
Risk-free interest rate	0.20%	0.30%
Expected dividend yield	0.00%	0.00%
Fair value:
Estimated fair value per warrant share	$1.21	$2.56
Shares underlying outstanding warrants classified as liabilities (in thousands)	2,920	3,099
Total estimated fair value of outstanding warrants (in thousands)	$3,543	$7,931

Financial_Instruments_Summary_2

Financial Instruments - Summary of Changes in Fair Value of Company's Level 3 Financial Liabilities (Detail) (Warrant Liability [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Warrant Liability [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Beginning Balance	$7,931	$8,070
Change in fair value of warrant liability	-3,892	-96
Exercise of warrants	-496	-43
Ending Balance	$3,543	$7,931

Other_Accrued_Liabilities_Summ

Other Accrued Liabilities - Summary of Other Accrued Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables And Accruals [Abstract]
Accrued outside services	$2,656	$1,249
Accrued professional services	355	263
Other accruals	76	133
Total other accrued liabilities	$3,087	$1,645

Royalty_Agreement_Additional_I

Royalty Agreement - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended	1 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2014	Sep. 30, 2012	Dec. 31, 2013
Royalty Agreement [Line Items]
Exercise price			$2.52		$2.52
Common stock, shares issued			66,102,000		54,344,000
Deferred revenue, amortized	$0.90	$2
Revenue participation right payments, rate			6.75%
Revenue participation right payments, term			10 years from the date of first commercial sale
Maximum term of revenue participation right payments			10 years
Royalty Agreement [Member]
Royalty Agreement [Line Items]
Revenue participation right payments			25	25
Fair value of warrants issued in connection with participation agreement			$3.10	$3.10
Number of warrants issued to RPI			2
Common stock, shares issued			777,107
Royalty Agreement [Member] | Warrant One [Member]
Royalty Agreement [Line Items]
Warrants Expiration Term			5 years
Warrant issued to purchase common stock			1,000,000
Exercise price			$3.48
Royalty Agreement [Member] | Warrant Two [Member]
Royalty Agreement [Line Items]
Warrants Expiration Term			5 years
Warrant issued to purchase common stock			1,000,000
Exercise price			$4.64

License_Agreements_Additional_

License Agreements - Additional Information (Detail) (USD $)	1 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2011	Jun. 30, 2012	Dec. 31, 2013	Dec. 31, 2014	Jan. 31, 2014
License Agreement Terms [Member] | Millennium License Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential pre-commercialization payments receivable				$57.50
Potential pre-commercialization milestone payments payable					9.2
Biogen Idec And Millennium [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Non refundable upfront amount recognized as revenue due to no further performance obligation	4
Biogen Idec [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Received and recognized milestone		1.5
Biogen Idec [Member] | License Agreement Terms [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Potential pre-commercialization payments receivable		58.5
Biogen Idec [Member] | Development Events [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payment depending on development			$2.50

Notes_Payable_Additional_Infor

Notes Payable - Additional Information (Detail) (USD $)	12 Months Ended	0 Months Ended
	Dec. 31, 2014	Feb. 27, 2015	Oct. 31, 2011	Oct. 18, 2011	Sep. 30, 2012	Sep. 19, 2012
	Tranches	Loan
	Installment
Debt Instrument [Line Items]
Maximum borrowing capacity			$25,000,000
Number of tranches for maximum borrowing	2
Number of installments	32
Line of credit facility final payment	937,500
Subsequent Event
Debt Instrument [Line Items]
Expiration date		1-Oct-16
Line of credit facility final payment	937,500	1,162,500
Interest only period start date		1-Mar-15
Interest only period end date		1-Feb-16
Number of remaining principal payments		8
Notes payable [Member]
Debt Instrument [Line Items]
Loan Agreement monthly arrears and interest date	1-Mar-13
Expiration date	1-Oct-15
Notes payable [Member] | Weighted Average [Member]
Debt Instrument [Line Items]
Weighted average annual effective interest rate on notes payable, including amortization of debt discounts and accretion	13.90%
Tranche one [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			10,000,000
Date of Loan and Security Agreement	31-Oct-11
Interest rate				8.95%
Tranche two [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity					$15,000,000
Line of credit facility remaining amount drawing date	30-Sep-12
Interest rate						9.00%

Notes_Payable_Summary_of_Futur

Notes Payable - Summary of Future Minimum Payments Under Loan Agreement (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Notes payable, balance	$9,257
Less current portion of notes payable	-9,257	-9,018
Non-current portion of notes payable		9,025
Notes payable [Member]
Debt Instrument [Line Items]
2015	8,814
Total minimum payments	8,814
Less amount representing interest	-352
Notes payable, gross	8,462
Unamortized discount on notes payable	-84
Accretion of final payment	$879

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commitments And Contingencies Disclosure [Line Items]
Rent expense	$0.40	$0.30	$0.40
Original Operating Lease [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease, office space leased	15,378
Operating lease expiration date	30-Apr-15
Operating lease agreement, original date	2014-01
Amended Operating Lease [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease, additional office space leased	6,105
Operating lease expiration date	30-Jun-15
Operating lease agreement, date of amendment	2014-06
Lease property description	The amended lease also includes an option to extend the lease for an additional six months, at a predetermined price, if exercised within a certain period.
Further Amended Operating Lease [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease expiration date	31-Dec-15
Operating lease agreement, date of amendment	2015-03

Commitments_and_Contingencies_2

Commitments and Contingencies - Aggregate Non-Cancelable Future Minimum Rental Payments under Operating Lease (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]
2015	$247
Total minimum rental payments due under operating leases	$247

Stockholders_Equity_Additional

Stockholders' Equity - Additional Information 1 (Detail) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended			2 Months Ended
	Mar. 04, 2014	Oct. 31, 2010	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 28, 2015	Dec. 31, 2011	Aug. 31, 2011	Feb. 27, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Preferred stock, shares authorized			10,000,000
Preferred stock, shares outstanding			0	0
Common stock, voting rights			One vote per share
Shares of common stock issued			66,102,000	54,344,000
Warrants, exercise prices per share			$2.52	$2.52
Proceeds from issuance of common stock and warrants in offering gross	$43,000,000	$15,500,000
Proceeds from issuance of common shares and warrants in offering, net	40,000,000
Proceeds from issuance of common stock through controlled equity offering facilities, net			14,292,000	11,986,000	17,620,000
Series A warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrant expiration description			The Series A warrants expired unexercised on December 4, 2014.
Series B warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrant expiration description			The Series B warrants will expire on or before the later of 30 days following any final date assigned by the Food and Drug Administration as the Prescription Drug User Fee Act action date for vosaroxin (the “PDUFA date”) and September 4, 2015, but in no event later than March 4, 2016
Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock issued			66,102,000	54,344,000	51,565,000		46,774,000
Underwritten Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock issued	4,650,000
Price per common share including accompanying warrants	$9.25
Underwritten Offering [Member] | Series A warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants, exercise prices per share	$8.50
Underwritten Offering [Member] | Series B warrants [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Warrants, exercise prices per share	$12
Controlled Equity Offering Facilities [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock, offering value								20,000,000
Common stock sales agreement, date			2011-08
Common stock sales agreement amended, date			2013-04
Issuance of common stock, remaining offering value			6,800,000
Controlled Equity Offering Facilities [Member] | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from issuance of common stock through controlled equity offering facilities, net						4,200,000
Issuance of common stock, remaining offering value									2,500,000
Controlled Equity Offering Facilities [Member] | Common Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Price per common share including accompanying warrants			$2.88
Common stock, shares sold			5,113,876
Proceeds from issuance of common shares and warrants in offering, gross			14,700,000
Proceeds from issuance of common stock through controlled equity offering facilities, net			14,300,000
Controlled Equity Offering Facilities [Member] | Common Stock [Member] | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Price per common share including accompanying warrants						$2.75
Common stock, shares sold						1,579,124
Proceeds from issuance of common shares and warrants in offering, gross						4,300,000
Proceeds from issuance of common stock through controlled equity offering facilities, net						4,200,000
Additional Controlled Equity Offerings Facilities [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in aggregate controlled equity offering agreement as per amendment			$30,000,000
Issuance of common stock, commission percentage			3.00%

Stockholders_Equity_Additional1

Stockholders' Equity - Additional Information 2 (Detail) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended	0 Months Ended	1 Months Ended
	Mar. 04, 2014	Oct. 31, 2010	Dec. 31, 2014	Jun. 03, 2011	Jan. 31, 2014	Jan. 31, 2013	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock issued			66,102,000				54,344,000
Proceeds from issuance of common stock and warrants in offering gross	$43,000,000	$15,500,000
Proceeds from issuance of common shares and warrants in offering, net	40,000,000
Warrants, exercise prices per share			$2.52				$2.52
Warrant liability			3,543,000				7,931,000
Number of shares of common stock reserved for issuance under latest plan			23,586,000
Shares Available for Future Grant			1,104,000
Options granted, Number of Shares			3,840,000
Stock Option Plans [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for issuance under latest plan			11,256,000
Shares Available for Future Grant			672,000
Stock Option Plans [Member] | New Employees [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option exercisable on first anniversary of vesting commencement date, percent			25.00%
Portion of option exercisable for each month over vesting period			0.020833333
Stock option plans, vesting period			4 years
Vesting rights			New employees, of which 25% of the shares subject to such options become exercisable on the first anniversary of the vesting commencement date, and 1/48th of the shares subject to such options become exercisable each month over the remainder of the four-year vesting period
Stock Option Plans [Member] | Existing Employees [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Portion of option exercisable for each month over vesting period			0.020833333
Stock option plans, vesting period			4 years
Vesting rights			Existing employees, of which 1/48th of the shares subject to such options become exercisable each month following the date of grant over a four-year vesting period
Stock Option Plans [Member] | New Non-Employee Board Members [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option plans, vesting period			2 years
Vesting rights			New non-employee members of the board of directors, of which 50% of the shares subject to such options become exercisable on each of the first and second anniversary of the vesting commencement date
Option exercisable on first and second anniversary of vesting commencement date, percent			50.00%
Stock Option Plans [Member] | Continuing Non-Employee Board Members [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Portion of option exercisable for each month over vesting period			0.041666667
Stock option plans, vesting period			2 years
Vesting rights			Continuing non-employee members of the board of directors, of which 1/24th of the shares subject to such options become exercisable each month following the date of grant over a two-year vesting period
2010 Offering [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock issued		7,357,610
Total warrants outstanding, shares		3,678,798	2,920,051
Proceeds from issuance of common stock and warrants in offering gross		15,500,000
Proceeds from issuance of common shares and warrants in offering, net		14,200,000
Warrants, maturity date		2015-10
Warrants, exercise prices per share		$2.52
Warrants exercised for cash, shares			179,427
Exercise of warrants for cash			452,000
Warrant liability			$3,500,000
2011 Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock reserved for issuance under latest plan				6,041,856
Shares Available for Future Grant			672,273	539,803
Shares of common stock available for issuance				4,400,000	2,173,764	2,062,609
Common stock available for issuance automatic increase period			10 years
Common stock available for issuance automatic increase maximum number of shares			4.00%
Options granted, Number of Shares			3,840,500
2011 Plan [Member] | Stock Option Plans [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Available for Future Grant				1,102,053

Stockholders_Equity_Additional2

Stockholders' Equity - Additional Information 3 (Detail) (USD $)	1 Months Ended	12 Months Ended
	Jan. 31, 2014	Dec. 31, 2014
		PurchasePeriod
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share of common stock value		25,000
Number of shares issued under employee stock purchase plan		99,049,000
Shares Available for Future Grant		1,104,000
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase price of a share as a percentage of fair market value		85.00%
Duration of offering period		12 months
Number of purchase periods in each offering period		2
Duration of each purchase period		6 months
Number of shares authorized under employee stock purchase plan		500,000
Common stock available for issuance automatic increase period		10 years
Common stock available for issuance automatic increase maximum number of shares		1.00%
Additional number of shares of common stock reserved for issuance	271,720
Shares Available for Future Grant		431,672

Stockholders_Equity_Schedule_o

Stockholders' Equity - Schedule of Warrants to Purchase Shares of Company's Common Stock (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Class of Warrant or Right [Line Items]
Warrants, exercise prices per share	$2.52	$2.52
Common Stock [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	11,898,000
Common Stock [Member] | August 2005 [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	14,000
Warrants, exercise prices per share	$54.60
Warrants Expiration Date	2015-08
Common Stock [Member] | October 2010 [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	2,920,000
Warrants, exercise prices per share	$2.52
Warrants Expiration Date	2015-10
Common Stock [Member] | March 2014 [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	4,650,000
Warrants, exercise prices per share	$12
Warrants Expiration Date	2016-03
Common Stock [Member] | April 2009 [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	2,876,000
Warrants, exercise prices per share	$1.32
Warrants Expiration Date	2016-04
Common Stock [Member] | October 2009 [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding and exercisable, shares	1,438,000
Warrants, exercise prices per share	$1.32
Warrants Expiration Date	2016-10

Stockholders_Equity_Shares_of_

Stockholders' Equity - Shares of Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2014
Class of Stock [Line Items]
Shares Available for Future Grant	1,104,000
Outstanding Securities	22,482,000
Total Shares Reserved	23,586,000
Warrants to purchase shares of common stock [Member]
Class of Stock [Line Items]
Outstanding Securities	11,898,000
Total Shares Reserved	11,898,000
Employee Stock Option
Class of Stock [Line Items]
Shares Available for Future Grant	672,000
Outstanding Securities	10,584,000
Total Shares Reserved	11,256,000
Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Shares Available for Future Grant	431,672
Total Shares Reserved	432,000

StockBased_Compensation_Summar

Stock-Based Compensation - Summary of Stock-Based Compensation Expense Related to Company's Stock-Based Awards (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$6,219	$3,885	$2,724
Employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	5,882	3,581	2,402
Non-employee stock-based compensation expense [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	337	304	322
Research and development [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	2,201	1,598	1,030
General and administrative [Member]
Share-based Compensation, Allocation and Classification in Financial Statements
Total stock-based compensation expense	$3,681	$1,983	$1,372

StockBased_Compensation_Summar1

Stock-Based Compensation - Summary of Weighted-Average and Total Estimated Grant Date Fair Values of Employee Stock Options Granted (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assumptions:
Expected dividend yield	0.00%
Fair value:
Options granted to employees (in thousands)	3,840,000
Stock Option Plans [Member]
Assumptions:
Expected term (years)	5 years 2 months 12 days	4 years 8 months 12 days	5 years 4 months 24 days
Expected volatility	88.10%	90.00%	88.70%
Risk-free interest rate	1.70%	1.00%	1.10%
Expected dividend yield	0.00%	0.00%	0.00%
Fair value:
Weighted-average estimated grant date fair value per share	$3.18	$3.63	$1.46
Stock Option Plans [Member] | Employee stock-based compensation expense [Member]
Fair value:
Options granted to employees (in thousands)	3,676,000	1,785,000	2,310,000
Total estimated grant date fair value (in thousands)	$11,704	$6,472	$3,377

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Estimated fair value of stock options, vested	$2,600,000	$3,400,000	$2,100,000
Payment of cash dividends	0
Dividend yield ratio	0.00%
Intrinsic value of options exercised	2,700,000	300,000	200,000
Tax benefits related to stock option exercised	0
Unrecognized stock-based compensation cost related to unvested stock options	$12,200,000
Weighted average term of unrecognized stock-based compensation expense	2 years 7 months 6 days

StockBased_Compensation_Summar2

Stock-Based Compensation - Summary of Stock Option Activity for Company's Stock Option Plans (Detail) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning Balance, Number of Shares	7,611
Options granted, Number of Shares	3,840
Options exercised, Number of Shares	-565
Options forfeited or expired, Number of Shares	-302
Ending Balance, Number of Shares	10,584
Vested and expected to vest as of December 31, 2014, Number of Shares	10,584
Exercisable as of December 31, 2014, Number of Shares	5,701
Beginning Balance, Weighted Average Exercise Price Per Share	$3.61
Options granted, Weighted Average Exercise Price Per Share	$4.54
Options exercised, Weighted Average Exercise Price Per Share	$2.17
Options forfeited or expired, Weighted Average Exercise Price Per Share	$7.13
Ending Balance, Weighted Average Exercise Price Per Share	$3.93
Vested and expected to vest as of December31, 2014, Weighted Average Exercise Price Per Share	$3.93
Exercisable as of December31,2014,Weighted Average Exercise Price Per Share	$3.86
Ending Balance, Weighted Average Remaining Contractual Term (Years)	7 years 7 months 17 days
Vested and expected to vest as of December31, 2014, Weighted Average Remaining Contractual Term (Years)	7 years 7 months 17 days
Exercisable as of December31, 2014,Weighted Average Remaining Contractual Term (Years)	6 years 6 months 26 days
Ending Balance, Aggregated Intrinsic Value	$3,885
Vested and expected to vest as of December31,2014,Aggregate Intrinsic Value	3,885
Ending Balance, Exercisable, Aggregate Intrinsic Value	$2,075

Income_Taxes_Loss_before_Provi

Income Taxes - Loss before Provision for Income Taxes (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
U.S. operations	($32,696)	($29,963)	($43,951)
Foreign operations	-10,306	-4,635
Loss before provision for income taxes	($43,002)	($34,598)	($43,951)

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]
Income tax provision	$0	$0	$0
Statutory income tax rate	34.00%
Net valuation allowance increased	14,600,000	12,600,000	13,700,000
Unrecognized tax positions	0	0
Domestic tax authority [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	364,500,000
Research and development tax credit carry-forwards	8,100,000
Net operating loss carry-forwards expiration	Expire at various dates beginning in 2018
State and local jurisdiction [Member]
Income Taxes [Line Items]
Net operating loss carry-forwards	235,800,000
Research and development tax credit carry-forwards	$7,200,000
Net operating loss carry-forwards expiration	Begin to expire in 2015

Income_Taxes_Income_Tax_Provis

Income Taxes - Income Tax Provision Amount Computed by Applying Statutory Income Tax Rate (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Tax at statutory rate	($14,620,000)	($11,763,000)	($14,943,000)
Current year net operating losses and temporary differences for which no tax benefit is recognized	14,104,000	12,457,000	5,351,000
Foreign tax rate differential	3,504,000	1,499,000
Deferred revenue	-1,934,000	-2,706,000	6,672,000
Change in fair value of warrant liability	-1,313,000	-16,000	2,570,000
Other permanent differences	259,000	529,000	350,000
Provision for income taxes	$0	$0	$0

Income_Taxes_Significant_Compo

Income Taxes - Significant Components of Deferred Tax Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred tax assets:
Federal and state net operating loss carry-forwards	$138,066	$123,490
Federal and state research credit carry-forwards	12,964	12,064
Capitalized research costs	5,199	5,119
Deferred revenue	2,394	4,668
Stock-based compensation	4,358	3,212
Property and equipment	129	133
Accrued liabilities	481	341
Gross deferred tax assets	163,591	149,027
Valuation allowance	($163,591)	($149,027)

Guarantee_and_Indemnification_

Guarantee and Indemnification - Additional Information (Detail) (USD $)	Dec. 31, 2014
Guarantees [Abstract]
Liabilities incurred in indemnification agreements	$0

Subsequent_Events_Additional_i

Subsequent Events - Additional information (Detail) (USD $)	12 Months Ended			0 Months Ended	2 Months Ended	1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 27, 2015	Feb. 28, 2015	Jan. 31, 2015
				Loan
Subsequent Event [Line Items]
Line of credit facility final payment	$937,500
Proceeds from issuance of common stock through controlled equity offering facilities, net	14,292,000	11,986,000	17,620,000
Controlled Equity Offering Facilities [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Price per common share including accompanying warrants	$2.88
Common stock, shares sold	5,113,876
Proceeds from issuance of common shares and warrants in offering, gross	14,700,000
Proceeds from issuance of common stock through controlled equity offering facilities, net	14,300,000
Further Amended Operating Lease [Member]
Subsequent Event [Line Items]
Operating lease expiration date	31-Dec-15
Subsequent Event
Subsequent Event [Line Items]
Interest only period start date				1-Mar-15
Interest only period end date				1-Feb-16
Number of remaining principal payments				8
Expiration date				1-Oct-16
Line of credit facility final payment	937,500			1,162,500
Line of credit facility final payment percentage	3.75%			4.65%
Prepayment penalty expiration date				29-Feb-16
Percentage of penalty for prepaying loan before maturity				2.00%
Warrants Expiration Term				5 years
Number of warrants issued				61,467
Warrants exercise price for shares				$2.22
Subsequent Event | Controlled Equity Offering Facilities [Member]
Subsequent Event [Line Items]
Proceeds from issuance of common stock through controlled equity offering facilities, net					4,200,000
Subsequent Event | Controlled Equity Offering Facilities [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Price per common share including accompanying warrants					$2.75
Common stock, shares sold					1,579,124
Proceeds from issuance of common shares and warrants in offering, gross					4,300,000
Proceeds from issuance of common stock through controlled equity offering facilities, net					$4,200,000
Subsequent Event | Further Amended Operating Lease [Member]
Subsequent Event [Line Items]
Operating lease expiration date						31-Dec-15

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data - Schedule of 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
Income Statement [Abstract]
Revenue	$896	$854	$1,989	$1,995	$1,989	$1,989	$1,989	$1,989	$5,734	$7,956	$3,754
Net loss:
Basic	-1,323	-15,325	-11,781	-14,573	-7,177	-7,607	-8,190	-11,624	-43,002	-34,598	-43,951
Diluted	($1,323)	($15,325)	($12,114)	($14,573)	($8,257)	($8,329)	($9,336)	($11,624)	($46,894)	($34,598)	($43,951)
Denominator:
Basic	63,041	60,549	60,246	56,313	54,060	51,698	51,630	51,587	60,057	52,249	48,146
Diluted	63,041	60,549	61,895	56,313	55,573	53,271	53,268	51,587	61,510	52,249	48,146
Net loss per common share:
Basic	($0.02)	($0.25)	($0.20)	($0.26)	($0.13)	($0.15)	($0.16)	($0.23)	($0.72)	($0.66)	($0.91)
Diluted	($0.02)	($0.25)	($0.20)	($0.26)	($0.15)	($0.16)	($0.18)	($0.23)	($0.76)	($0.66)	($0.91)