Molecular Templates (MTEM) 10-Q 4 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 25, 2013
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'THLD	'
Entity Registrant Name	'THRESHOLD PHARMACEUTICALS INC	'
Entity Central Index Key	'0001183765	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	59,224,123

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$4,001	$11,029
Marketable securities	87,913	59,819
Collaboration receivable	5,545	15,635
Prepaid expenses and other current assets	1,819	1,167
Total current assets	99,278	87,650
Property and equipment, net	708	812
Other assets	1,059	1,059
Total assets	101,045	89,521
Current liabilities:	'	'
Accounts payable	1,375	908
Accrued clinical and development expenses	8,291	5,750
Accrued liabilities	2,489	2,257
Deferred revenue, current	12,722	8,536
Total current liabilities	24,877	17,451
Warrant liability	23,790	32,558
Deferred revenue, non-current	69,628	53,097
Deferred rent	250	268
Total liabilities	118,545	103,374
Commitments and contingencies (Note 7)	'	'
Stockholders' equity (deficit):	'	'
Preferred stock, $0.001 par value, 2,000,000 shares authorized; no shares issued and outstanding	'	'
Common stock, $0.001 par value, shares authorized: 150,000,000 shares; issued and outstanding: 59,174,123 shares at September 30, 2013 and 56,431,207 shares at December 31, 2012	59	56
Additional paid-in capital	326,492	309,343
Accumulated other comprehensive gain (loss)	38	11
Accumulated deficit	-344,089	-323,263
Total stockholders' equity (deficit)	-17,500	-13,853
Total liabilities and stockholders' equity (deficit)	$101,045	$89,521

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]	'	'
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	'	'
Preferred stock, shares outstanding	'	'
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	59,174,123	56,431,207
Common stock, shares outstanding	59,174,123	56,431,207

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]	'	'	'	'
Revenue	$3,181	$1,797	$9,283	$3,846
Operating expenses:	'	'	'	'
Research and development	6,350	4,039	20,801	12,623
General and administrative	2,051	1,741	6,732	5,229
Total operating expenses	8,401	5,780	27,533	17,852
Loss from operations	-5,220	-3,983	-18,250	-14,006
Interest income (expense), net	34	25	104	55
Other income (expense)	6,379	2,967	-2,559	-85,572
Income (loss) before provision for income taxes	1,193	-991	-20,705	-99,523
Provision for income taxes	17	'	121	'
Net income (loss)	1,176	-991	-20,826	-99,523
Other comprehensive income (loss), net of tax:	'	'	'	'
Unrealized gain (loss) on available-for-sale securities	65	27	27	15
Comprehensive income (loss)	$1,241	($964)	($20,799)	($99,508)
Net income (loss) per common share:	'	'	'	'
Basic	$0.02	($0.02)	($0.36)	($1.86)
Diluted	($0.08)	($0.06)	($0.36)	($1.86)
Weighted average number of shares used in per common share calculations:	'	'	'	'
Basic	58,542	55,654	57,362	53,516
Diluted	63,561	64,405	59,871	53,516

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:	'	'
Net loss	($20,826)	($99,523)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:	'	'
Depreciation and amortization	1,094	668
Stock-based compensation expense	3,556	2,087
Change in common stock warrant value	2,559	85,572
Changes in operating assets and liabilities:	'	'
Collaboration receivable	10,090	-17,457
Prepaid expenses and other assets	-652	-606
Accounts payable	467	-1,650
Accrued clinical and development expenses	2,541	1,980
Accrued liabilities	232	80
Deferred rent	-18	120
Deferred revenue	20,717	53,654
Net cash provided by operating activities	19,760	24,925
Cash flows from investing activities:	'	'
Acquisition of property and equipment	-106	-328
Acquisition of marketable securities	-88,951	-75,413
Proceeds from sales of marketable securities	3,203	10,600
Proceeds from maturities of marketable securities	56,797	21,522
Net cash used in investing activities	-29,057	-43,619
Cash flows from financing activities:	'	'
Proceeds from issuance of common stock and warrants, net of offering expenses	2,269	21,446
Net cash provided by financing activities	2,269	21,446
Net increase (decrease) in cash and cash equivalents	-7,028	2,752
Cash and cash equivalents, beginning of period	11,029	5,882
Cash and cash equivalents, end of period	$4,001	$8,634

Organization_and_Summary_of_Si

Organization and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Organization and Summary of Significant Accounting Policies	'
	NOTE 1 — ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	The Company
	Threshold Pharmaceuticals, Inc. is a biotechnology company focused on the discovery and development of drugs targeting tumor hypoxia, the low oxygen condition found in microenvironments of most solid tumors as well as the bone marrows of some hematologic malignancies. The Company was incorporated in the State of Delaware on October 17, 2001. In June 2005, the Company formed a wholly-owned subsidiary, THLD Enterprises (UK), Limited in the United Kingdom for purposes of conducting clinical trials in Europe. There is currently no financial activity related to this entity. Threshold operates in one business segment.
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements. In the opinion of management, all adjustments, consisting of normal recurring adjustments necessary for the fair statement of results for the periods presented, have been included. The results of operations of any interim period are not necessarily indicative of the results of operations for the full year or any other interim period.
	The preparation of condensed consolidated financial statements requires management to make estimates and assumptions that affect the recorded amounts reported therein. A change in facts or circumstances surrounding the estimate could result in a change to estimates and impact future operating results.
	The unaudited condensed consolidated financial statements and related disclosures have been prepared with the presumption that users of the interim unaudited condensed consolidated financial statements have read or have access to the audited consolidated financial statements for the preceding fiscal year. The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all the information and footnotes required by accounting principles generally accepted in the United States of America. Accordingly, these unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2012 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on March 7, 2013.
	The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, and reflect the elimination of intercompany accounts and transactions.
	Revenue Recognition
	The Company recognizes revenue in accordance with ASC 605 “Revenue Recognition”, subtopic ASC 605-25 “Revenue with Multiple Element Arrangements” and subtopic ASC 605-28 “Revenue Recognition-Milestone Method”, which provides accounting guidance for revenue recognition for arrangements with multiple deliverables and guidance on defining the milestone and determining when the use of the milestone method of revenue recognition for research and development transactions is appropriate, respectively.
	The Company’s revenues are related to its collaboration arrangement with Merck KGaA, which was entered in February 2012. The collaboration with Merck KGaA provides for various types of payments to the Company, including non-refundable upfront license, milestone and royalty payments. The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed or determinable, and collectability is reasonably assured. The Company will also receive reimbursement for Merck KGaA’s 70% share for eligible worldwide development expenses for TH-302. Such reimbursement is reflected as a reduction of operating expenses and not as revenue.
	For multiple-element arrangements, each deliverable within a multiple deliverable revenue arrangement is accounted for as a separate unit of accounting if both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company’s control. The deliverables under the Merck KGaA agreement have been determined to be a single unit of accounting and as such the revenue relating to this unit of accounting will be recorded as deferred revenue and recognized ratably over the term of its estimated performance period under the agreement, which is the product development period. The Company determines the estimated performance period and it will be periodically reviewed based on the progress of the related product development plan. The effect of a change made to an estimated performance period and therefore revenue recognized ratably would occur on a prospective basis in the period that the change was made.
	Deferred revenue associated with a non-refundable payment received under a collaborative agreement for which the performance obligations are terminated will result in an immediate recognition of any remaining deferred revenue in the period that termination occurred provided that all performance obligations have been satisfied.
	The Company recognizes revenue from milestone payments when: (i) the milestone event is substantive and its achievability has substantive uncertainty at the inception of the agreement, and (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone earned. Milestone payments are considered substantive if all of the following conditions are met: the milestone payment (a) is commensurate with either the Company’s performance subsequent to the inception of the arrangement to achieve the milestone or the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the Company’s performance subsequent to the inception of the arrangement to achieve the milestone, (b) relates solely to past performance, and (c) is reasonable relative to all of the deliverables and payment terms (including other potential milestone consideration) within the arrangement. See Note 3, “Collaboration Arrangements,” for analysis of milestone events deemed to be substantive or non-substantive.

Net_Income_Loss_Per_Common_Sha

Net Income (Loss) Per Common Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Net Income (Loss) Per Common Share	'
	NOTE 2 — NET INCOME (LOSS) PER COMMON SHARE
	Basic net income (loss) per common share is computed by dividing net income (loss) by the weighted-average number of common shares outstanding during the period. Diluted net income (loss) per common share is computed by giving effect to all potential dilutive common shares, including outstanding options and warrants.
	Potential dilutive common shares also include the dilutive effect of the common stock underlying in-the-money stock options and warrants that were calculated based on the average share price for each period using the treasury stock method. Under the treasury stock method, the exercise price of an option or warrant is assumed to be used to repurchase shares in the current period. In addition, the average amount of compensation cost for in-the-money options, if any, for future service that the Company has not yet recognized when the option is exercised, is also assumed to repurchase shares in the current period. A reconciliation of the numerator and denominator used in the calculation is as follows (in thousands, except per share amounts):
		Three Months Ended						Nine months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Numerator:
	Net income (loss) - basic	$	1,176		$	(991	)	$	(20,826	)	$	(99,523	)
	Less: noncash income from change in fair value of common stock warrants		(6,379	)		(2,967	)		(557	)		—
	Net loss - diluted		(5,203	)		(3,958	)		(21,383	)		(99,523	)
	Denominator:
	Weighted average common shares outstanding		58,542			55,654			57,362			53,516
	Dilutive effect of warrants		5,019			8,751			2,509			—
	Weighted-average common shares outstanding and potential dilutive common shares - diluted		63,561			64,405			59,871			53,516
	Net income (loss) per share
	Basic	$	0.02		$	(0.02	)	$	(0.36	)	$	(1.86	)
	Diluted	$	(0.08	)	$	(0.06	)	$	(0.36	)	$	(1.86	)
	The following outstanding warrants, options and purchase rights under the Company’s 2004 Employee Stock Purchase Plan were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an antidilutive effect. The amounts disclosed below are prior to the application of the treasury stock method (in thousands):
		Three Months  Ended						Nine months  Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Shares issuable upon exercise of warrants		—			—			4,034			11,726
	Shares issuable upon exercise of stock options		6,560			5,129			6,560			5,129
	Shares issuable related to the ESPP		28			48			28			48

Collaboration_Arrangements

Collaboration Arrangements	9 Months Ended
	Sep. 30, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Collaboration Arrangements	'
	NOTE 3 — COLLABORATION ARRANGEMENTS
	On February 3, 2012, the Company entered into a global license and co-development agreement with Merck KGaA, of Darmstadt, Germany, to co-develop and commercialize TH-302, the Company’s small molecule hypoxia-targeted drug. Under the terms of the agreement, Merck KGaA will receive co-development rights, exclusive global commercialization rights and will provide the Company an option to co-commercialize TH-302 in the United States. The Company received an upfront payment of $25 million. To date the Company has also received $72.5 million in milestone payments, including $42.5 million received during the three months ended March 31, 2013. The milestones received to date were not deemed to be substantive milestones because the work related to the achievement of these items was predominately completed prior to the inception of the arrangement or performed primarily by Merck KGaA. The Company is eligible to receive additional potential milestone payments of up to $112.5 million in regulatory and development milestones, including $12.5 million that may be received in 2013, and $340 million in commercialization milestones.
	In the United States, the Company will have primary responsibility for development of TH-302 in the soft tissue sarcoma indication. The Company and Merck KGaA are jointly developing TH-302 in all other cancer indications being pursued. Merck KGaA will pay 70% of worldwide development expenses for TH-302. Subject to FDA approval in the United States, Merck KGaA will initially be responsible for commercialization of TH-302 with the Company receiving a tiered, double-digit royalty on sales. Under the royalty-bearing portion of the agreement, Threshold retains the option to co-promote TH-302 in the United States. Additionally, the Company retains the option to co-commercialize TH-302, upon the achievement of certain sales and regulatory milestones, allowing the Company to participate in up to 50% of the profits in the United States depending on total sales. Outside of the United States, Merck KGaA will be solely responsible for the commercialization of TH-302 with the Company receiving a tiered, double-digit royalty on sales in these territories. The agreement will continue on a country-by-country basis until the later of the last to expire patent covering TH-302 in such country or ten years following the commercial launch of a product containing TH-302 in such country, unless terminated earlier. Merck KGaA has the right to terminate the agreement after the achievement of certain milestones, and each party has the right to terminate the agreement following an uncured material breach by the other party.
	The Company’s deliverables under the Merck KGaA agreement, which include delivery of the rights and license for TH-302 and performance of research and development activities, have been determined to be a single unit of accounting. The delivered license does not have standalone value at the inception of the arrangement due to the Company’s proprietary expertise with respect to the licensed compound and related ongoing developmental participation under the global license and co-development agreement, which is required for Merck KGaA to fully realize the value from the delivered license. Therefore, the revenue relating to this unit of accounting will be recorded as deferred revenue and recognized over the estimated performance period under the agreement, which is the product development period. The Company recorded the $97.5 million of upfront payment and milestones received as deferred revenue, including a $30 million milestone payment achieved and received during the three months ended March 31, 2013, and is amortizing them ratably over its estimated period of performance, which the Company currently estimates to end on March 31, 2020. As a result, the Company recognized $3.2 million and $9.3 million of revenue during the three and nine months ended September 30, 2013, respectively, compared to $1.8 and $3.8 million for the three and nine months ended September 30, 2012, respectively. The Company will periodically review and, if necessary, revise the estimated periods of performance of our collaboration. The Company also earned $5.5 million and $11.6 million reimbursement for eligible worldwide development expenses for TH-302 from Merck KGaA during the three and nine months ended September 30, 2013, respectively compared to $5.0 million and $10.0 million for the three and nine months ended September 30, 2012, respectively. Such earned reimbursement has been reflected as a reduction of operating expenses.
	Of the remaining potential future milestones, $112.5 million are related to regulatory and development milestones and $340 million are related to commercialization milestones that may be received under the Merck KGaA Agreement. Regulatory milestones include the filing and acceptance of regulatory applications for marketing approval in major markets. Development milestones include primarily the initiation of various phases of clinical trials. Commercialization milestones include the achievement of first commercial sales in a particular market or annual product sales in excess of a pre-specified threshold. At the inception of the collaboration agreement the Company assessed regulatory and development milestones to be substantive where there was substantive scientific and regulatory uncertainty of achievement, the amounts of payments assigned were considered to be commensurate with the enhancement of the value of the delivered rights and license of TH-302 and the Company’s performance is necessary to the achievement of the milestone. Accordingly, the Company will recognize payments related to the achievement of such milestones, if any, when such milestone is achieved. Regulatory and development milestones that do not meet these conditions were considered non-substantive and payments related to the achievement of such milestones, if any, will be recorded as deferred revenue and amortized ratably over the estimated period of performance. Final determination of whether a development or regulatory milestone is substantive will depend upon the Company’s role in achieving the milestone. The specific role and responsibilities related to the regulatory and development activities for certain of these milestones have yet to be determined and may change during the development period. Under the Merck KGaA agreement, Merck KGaA will initially be responsible for commercialization activities and the Company initially may not be involved in the achievement of these commercialization milestones. These commercialization milestones would typically be achieved after the completion of the Company’s regulatory and development activities. The Company would account for the commercialization milestones in the same manner as royalties, with revenue recognized upon achievement of the milestone, if there are no development related future obligations at the time of receipt of the commercial milestones.

Stockholders_Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Stockholders' Equity	'
	NOTE 4— STOCKHOLDERS’ EQUITY
	Common Stock Warrants
	The Company accounts for its common stock warrants in accordance with ASC 815 that clarifies the determination of whether an instrument (or an embedded feature) is indexed to an entity’s own stock, which would qualify for classification as liabilities. The guidance required the Company’s outstanding warrants to be classified as liabilities and to be fair valued at each reporting period, with the changes in fair value recognized as other income (expense) in the Company’s consolidated statements of operations.
	During nine months ended September 30, 2013, warrants to purchase 2,367,636 shares of common stock were cashless exercised for 1,555,043 shares of common stock. In addition, during the nine months ended September 30, 2013, warrants to purchase 893,475 shares of common stock were exercised for net proceeds of approximately $1.8 million. As of the date of exercise of the warrants, the Company transferred the fair value of the warrants of approximately $3.8 million and $11.3 million from warrant liability into stockholders’ equity for the three and nine months ended September 30, 2013, respectively.
	At September 30, 2013 and December 31, 2012, the Company had warrants outstanding to purchase 0 and 3,058,811 shares of common stock, respectively, from the August 2008 offering. All of the warrants related to the August 2008 offering had been exercised prior to their expiration date of August 29, 2013. During the three and nine months ended September 30, 2013, the change in fair value of $0.6 million of noncash income and $2.5 million of noncash expense, respectively, related to the August 2008 warrants was recorded as other income (expense) in the Company’s consolidated statement of operations.
	At September 30, 2013 and December 31 2012, the Company had warrants outstanding to purchase 4,287,940 shares of common stock from the October 2009 offering. The fair value of these warrants on September 30, 2013 and December 31, 2012 was determined using a Black Scholes valuation model with the following level 3 inputs:
		September 30,			December 31,
		2013			2012
	Risk-free interest rate		0.1	%		0.25	%
	Expected life (in years)		1.01			1.76
	Dividend yield		—			—
	Volatility		56	%		98	%
	Stock price	$	4.65		$	4.21
	During the three and nine months September 30, 2013, the change in fair value of $2.8 million and $0.6 million of noncash income, respectively, related to the October 2009 warrants was recorded as other income (expense) in the Company’s consolidated statement of operations.
	At September 30, 2013 and December 31, 2012, the Company had warrants outstanding to purchase 4,033,783 and 4,236,083 shares of common stock, respectively from the March 2011 offering. The fair value of these warrants on September 30, 2013 and December 31, 2012 was determined using a Black Scholes valuation model with the following level 3 inputs:
		September 30,			December 31,
		2013			2012
	Risk-free interest rate		0.63	%		0.72	%
	Expected life (in years)		2.46			3.21
	Dividend yield		—			—
	Volatility		87	%		94	%
	Stock price	$	4.65		$	4.21
	During the three and nine months ended September 30, 2013, the change in fair value of $2.9 million of noncash income and $0.6 million of noncash expense, respectively, related to the March 2011 warrants was recorded as other income (expense) in the Company’s consolidated statement of operations.
	The following table sets forth the Company’s financial liabilities, related to warrants issued in the August 2008, October 2009 and March 2011 offerings, subject to fair value measurements as of September 30, 2013 and December 31, 2012:
	(in thousands)	Fair Value as of			Basis of Fair Value Measurements
		September 30,
		2013			Level 1			Level 2		Level 3
	August 2008 warrants	$	—		$	—		$	—	$	—
	October 2009 warrants		11,406			—			—		11,406
	March 2011 warrants		12,384			—			—		12,384
	Total common stock warrants	$	23,790		$	—		$	—	$	23,790
	(in thousands)	Fair Value as of			Basis of Fair Value Measurements
		December 31,
		2012			Level 1			Level 2		Level 3
	August 2008 warrants	$	8,014		$	—		$	—	$	8,014
	October 2009 warrants		11,963			—			—		11,963
	March 2011 warrants		12,581			—			—		12,581
	Total common stock warrants	$	32,558		$	—		$	—	$	32,558
	The following table is a reconciliation of the warrant liability measured at fair value using level 3 inputs (in thousands):
		Warrant Liability
	Balance at December 31, 2012	$	32,558
	Change in fair value of common stock warrants during nine months ended September 30, 2013		2,559
	Exercise of warrants during nine months ended September 30, 2013		(11,327	)
	Balance at September 30, 2013	$	23,790

Stock_Based_Compensation

Stock Based Compensation	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock Based Compensation	'
	NOTE 5— STOCK BASED COMPENSATION
	The Company recognizes stock-based compensation in accordance with ASC 718, “Compensation—Stock Compensation.” Stock-based compensation expense, which consists of the compensation cost for employee stock options and ESPP, and the value of options issued to non-employees for services rendered, was allocated to research and development and general and administrative in the unaudited condensed consolidated statements of operations as follows (in thousands):
		Three Months  Ended						Nine months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Amortization of stock-based compensation:
	Research and development	$	622		$	471		$	1,818		$	1,082
	General and administrative		609			473			1,738			1,005
		$	1,231		$	944		$	3,556		$	2,087
	Valuation Assumptions
	The Company estimated the fair value of stock options granted using the Black-Scholes option-pricing formula and a single option award approach. This fair value is being amortized ratably over the requisite service periods of the awards, which is generally the vesting period. The fair value of employee stock options and employee purchase rights under the Company’s ESPP was estimated using the following weighted-average assumptions for the three and nine months ended September 30, 2013 and 2012:
		Three Months  Ended						Nine months  Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Employee Stock Options
	Risk-free interest rate		1.79	%		1.03	%		1.14	%		1.13	%
	Expected term (in years)		6.08			6.08			5.97			5.99
	Dividend yield		—			—			—			—
	Volatility		100	%		98	%		101	%		106	%
	Weighted-average fair value of stock options granted	$	4.21		$	5.87		$	4.04		$	5.12
		Three Months  Ended						Nine months  Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Employee Stock Purchase Plan (ESPP):
	Risk-free interest rate		0.19	%		0.21	%		0.19	%		0.21	%
	Expected term (in years)		1.25			1.25			1.25			1.25
	Dividend yield		—			—			—			—
	Volatility		72	%		111	%		77	%		111	%
	Weighted-average fair value of ESPP purchase rights	$	2.22		$	4.62		$	2.27		$	3.46
	To determine the expected term of the Company’s employee stock options granted, the Company utilized the simplified approach as defined by SEC Staff Accounting Bulletin No. 107, “Share-Based Payment” (“SAB 107”). To determine the risk-free interest rate, the Company utilized an average interest rate based on U.S. Treasury instruments with a term consistent with the expected term of the Company’s stock based awards. To determine the expected stock price volatility for the Company’s stock based awards, the Company utilized historical volatilities for the Company in the current year periods and examined historical volatilities for industry peers as well as the Company and utilized a blend of the historical volatilities of the Company and its industry peers for prior year periods. The fair value of all the Company’s stock based awards assumes no dividends as the Company does not anticipate paying cash dividends on its common stock.
	Employee Stock-based Compensation Expense
	As required by ASC 718, the Company recognized $1.2 million and $3.5 million of stock-based compensation expense related to stock options and purchase rights, under the Company’s stock option plans and ESPP, for the three and nine months ended September 30, 2013, respectively and $0.8 million and $1.9 million of stock based compensation for the three and nine months ended September 30, 2012, respectively. As of September 30, 2013, the total unrecognized compensation cost related to unvested stock-based awards granted to employees under the Company’s stock option plans was approximately $11.6 million before forfeitures. This cost will be recorded as compensation expense on a straight-line basis over the remaining weighted average requisite service period of approximately 2.5 years.
	Non-employee Stock-based Compensation Expense
	The Company accounts for equity instruments issued to non-employees in accordance with ASC 505, “Equity.” The equity instruments consisting of stock options are valued using the Black-Scholes option pricing model. The values attributable to these options are amortized over the service period and the unvested portion of these options is remeasured at each vesting date. In connection with the grant of stock options to non-employees, the Company recorded stock-based compensation of approximately $36,000 and $0.1 million for the three and nine months ended September 30, 2013, respectively, and $0.1 and $0.2 million for the three and nine months ended September 30, 2012, respectively.
	Equity Incentive Plans
	2004 Equity Incentive Plan On January 1, 2013, an additional 1,250,000 shares was authorized for issuance under the 2004 Equity Incentive Plan (“2004 Incentive Plan”), pursuant to the annual automatic increase to the authorized shares under the 2004 Incentive Plan. At September 30, 2013, 160,214 shares were authorized and available for issuance under the 2004 Equity Incentive Plan.
	The following table summarizes stock option activity under the Company’s 2004 Equity Incentive Plan:
	Options	Number of			Weighted-			Weighted-			Aggregate
		Shares			Average			Average			Intrinsic
					Exercise			Remaining			Value
					Price			Contractual
								Term
	Outstanding at December 31, 2012		5,098,972		$	3.18			—			—
	Granted		1,653,500		$	5.1			—			—
	Exercised		(127,153	)	$	1.59			—			—
	Forfeitures		(65,303	)	$	7.15			—			—
	Outstanding at September 30, 2013		6,560,016		$	3.66			7.83		$	10,534,778
	Vested and expected to vest September 30, 2013		6,504,707		$	3.64			7.82		$	10,518,742
	Exercisable at September 30, 2013		3,361,581		$	2.67			7.01		$	8,034,963
	The total intrinsic value of stock options exercised during the nine months ended September 30, 2013 and 2012 were $0.5 million and $1.4 million, respectively, as determined at the date of the option exercise. Cash received from stock option exercises was $0.2 million and $0.4 million for each of the nine months ended September 30, 2013 and 2012, respectively. The Company issues new shares of common stock upon exercise of options. In connection with these exercises, there was no tax benefit realized by the Company due to the Company’s current loss position.
	2004 Employee Stock Purchase Plan On January 1, 2013, an additional 100,000 shares was authorized for issuance under the 2004 Employee Stock Purchase Plan (“2004 Purchase Plan”) pursuant to the annual automatic increase to the authorized shares under the 2004 Purchase Plan. For the nine months ended September 30, 2013, plan participants had purchased 167,245 shares at an average purchase price of $1.69. At September 30, 2013, plan participants had $0.1 million withheld to purchase stock on February 14, 2014, which is included in accrued liabilities on the accompanying unaudited condensed consolidated balance sheet. At September 30, 2013, 235,896 shares were authorized and available for issuance under the ESPP.

Fair_Value_Measurements_and_Ma

Fair Value Measurements and Marketable Securities	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Fair Value Measurements and Marketable Securities	'
	NOTE 6— FAIR VALUE MEASUREMENTS AND MARKETABLE SECURITIES
	The Company accounts for its marketable securities in accordance with ASC 820 “Fair Value Measurements and Disclosures.” ASC 820 defines fair value, establishes a framework for measuring fair value in GAAP, and expands disclosures about fair value measurements. ASC 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. ASC 820 also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value:
	Level 1 - Quoted prices in active markets for identical assets or liabilities.
	Level 2 - Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	The Company utilizes the market approach to measure fair value for its financial assets and liabilities. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. For Level 2 securities that have market prices from multiples sources, a “consensus price” or a weighted average price for each of these securities can be derived from a distribution-curve-based algorithm which includes market prices obtained from a variety of industrial standard data providers (e.g. Bloomberg), security master files from large financial institutions, and other third-party sources. Level 2 securities with short maturities and infrequent secondary market trades are typically priced using mathematical calculations adjusted for observable inputs when available.
	The following table sets forth the Company’s financial assets (cash equivalents and marketable securities) at fair value on a recurring basis as of September 30, 2013 and December 31, 2012:
		Fair Value as of		Basis of Fair Value Measurements
		September 30,
	(in thousands)	2013		Level 1			Level 2			Level 3
	Money market funds	$	4,001	$	4,001		$	—		$	—
	Certificates of deposit		1,880		—			1,880			—
	Corporate debt securities		56,484		—			56,484			—
	U.S. Government securities		26,089		—			26,089			—
	Municipal securities		1,211		—			1,211			—
	Commercial paper		2,249		—			2,249			—
	Total cash equivalents and marketable securities	$	91,914	$	4,001		$	87,913		$	—
		Fair Value as of		Basis of Fair Value Measurements
		December 31,
	(in thousands)	2012		Level 1			Level 2			Level 3
	Money market funds	$	5,886	$	5,886		$	—		$	—
	Certificates of deposit		1,185		—			1,185			—
	Corporate debt securities		20,242		—			20,242			—
	U.S. Government securities		27,899		—			27,899			—
	Commercial paper		15,613		—			15,613			—
	Total cash equivalents and marketable securities	$	70,825	$	5,886		$	64,939		$	—
	The Company invests in highly-liquid, investment-grade securities. The following is a summary of the Company’s available-for-sale securities at September 30, 2013 and December 31, 2012:
	As of September 30, 2013 (in thousands):	Cost Basis		Unrealized			Unrealized			Fair
				Gain			Loss			Value
	Money market funds	$	4,001	$	—		$	—		$	4,001
	Certificates of deposit		1,880		—			—			1,880
	Corporate debt securities		56,466		23			(5	)		56,484
	U.S. Government securities		26,071		19			(1	)		26,089
	Municipal securities		1,210		1			—			1,211
	Commercial paper		2,249		—			—			2,249
			91,877		43			(6	)		91,914
	Less cash equivalents		4,001		—			—			4,001
	Total marketable securities	$	87,876	$	43		$	(6	)	$	87,913
	As of December 31, 2012 (in thousands):	Cost Basis		Unrealized			Unrealized			Fair
				Gain			Loss			Value
	Money market funds	$	5,886	$	—		$	—		$	5,886
	Certificates of deposit		1,185		—			—			1,185
	Corporate debt securities		20,237		6			(1	)		20,242
	U.S. Government securities		27,893		12			(6	)		27,899
	Commercial paper		15,613		—			—			15,613
			70,814		18			(7	)		70,825
	Less cash equivalents		11,006		—			—			11,006
	Total marketable securities	$	59,808	$	18		$	(7	)	$	59,819
	There were no realized gains or losses in the three and nine months ended September 30, 2013 and 2012.
	As of September 30, 2013, weighted average maturity for the Company’s available for sale securities was approximately 7 months, with the longest maturity being May 2015.
	The following table provides the breakdown of the marketable securities with unrealized losses at September 30, 2013 (in thousands):
		In loss position for less
		than twelve months
	As of September 30, 2013 (in thousands):	Fair Value		Unrealized Loss
	U.S. Government securities	$	3,002	$	(1	)
	Corporate debt securities		17,435		(5	)
	Total marketable securities	$	20,437	$	(6	)
	The Company determined the fair value of the liability associated with its warrants to purchase 8.3 million shares of outstanding common stock using a Black-Scholes Model. See detailed discussion in Note 4 — Stockholders’ Equity.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	NOTE 7— COMMITMENTS AND CONTINGENCIES
	The Company leases certain of its facilities under noncancelable leases, which qualify for operating lease accounting treatment under ASC 840, “Leases,” and, as such, these facilities are not included on its unaudited condensed consolidated balance sheets. The future rental payments required by the Company for all of its facilities under noncancelable operating leases are as follows (in thousands):
	Years Ending December 31,
	2013	$	161
	2014		651
	2015		674
	2016		702
	2017		238
	Total	$	2,426
	Indemnification
	The Company enters into indemnification provisions under its agreements with other companies in the ordinary course of business, including business partners, contractors and parties performing its clinical trials. Pursuant to these arrangements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party as a result of the Company’s activities. The duration of these indemnification agreements is generally perpetual. The maximum potential amount of future payments the Company could be required to make under these agreements is not determinable. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the Company believes the estimated fair value of these agreements is minimal. The Company maintains commercial general liability insurance and products liability insurance to offset certain of its potential liabilities under these indemnification provisions. Accordingly, the Company has not recognized any liabilities relating to these agreements as of September 30, 2013.
	The Company’s bylaws provide that it is required to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers, other than liabilities arising from willful misconduct of a culpable nature, to the fullest extent permissible by applicable law; and to advance their expenses incurred as a result of any proceeding against them as to which they could be indemnified.

Organization_and_Summary_of_Si1

Organization and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements. In the opinion of management, all adjustments, consisting of normal recurring adjustments necessary for the fair statement of results for the periods presented, have been included. The results of operations of any interim period are not necessarily indicative of the results of operations for the full year or any other interim period.
	The preparation of condensed consolidated financial statements requires management to make estimates and assumptions that affect the recorded amounts reported therein. A change in facts or circumstances surrounding the estimate could result in a change to estimates and impact future operating results.
	The unaudited condensed consolidated financial statements and related disclosures have been prepared with the presumption that users of the interim unaudited condensed consolidated financial statements have read or have access to the audited consolidated financial statements for the preceding fiscal year. The condensed consolidated balance sheet at December 31, 2012 has been derived from the audited financial statements at that date but does not include all the information and footnotes required by accounting principles generally accepted in the United States of America. Accordingly, these unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2012 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on March 7, 2013.
	The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, and reflect the elimination of intercompany accounts and transactions.
Revenue Recognition	'
	Revenue Recognition
	The Company recognizes revenue in accordance with ASC 605 “Revenue Recognition”, subtopic ASC 605-25 “Revenue with Multiple Element Arrangements” and subtopic ASC 605-28 “Revenue Recognition-Milestone Method”, which provides accounting guidance for revenue recognition for arrangements with multiple deliverables and guidance on defining the milestone and determining when the use of the milestone method of revenue recognition for research and development transactions is appropriate, respectively.
	The Company’s revenues are related to its collaboration arrangement with Merck KGaA, which was entered in February 2012. The collaboration with Merck KGaA provides for various types of payments to the Company, including non-refundable upfront license, milestone and royalty payments. The Company recognizes revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed or determinable, and collectability is reasonably assured. The Company will also receive reimbursement for Merck KGaA’s 70% share for eligible worldwide development expenses for TH-302. Such reimbursement is reflected as a reduction of operating expenses and not as revenue.
	For multiple-element arrangements, each deliverable within a multiple deliverable revenue arrangement is accounted for as a separate unit of accounting if both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company’s control. The deliverables under the Merck KGaA agreement have been determined to be a single unit of accounting and as such the revenue relating to this unit of accounting will be recorded as deferred revenue and recognized ratably over the term of its estimated performance period under the agreement, which is the product development period. The Company determines the estimated performance period and it will be periodically reviewed based on the progress of the related product development plan. The effect of a change made to an estimated performance period and therefore revenue recognized ratably would occur on a prospective basis in the period that the change was made.
	Deferred revenue associated with a non-refundable payment received under a collaborative agreement for which the performance obligations are terminated will result in an immediate recognition of any remaining deferred revenue in the period that termination occurred provided that all performance obligations have been satisfied.
	The Company recognizes revenue from milestone payments when: (i) the milestone event is substantive and its achievability has substantive uncertainty at the inception of the agreement, and (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone earned. Milestone payments are considered substantive if all of the following conditions are met: the milestone payment (a) is commensurate with either the Company’s performance subsequent to the inception of the arrangement to achieve the milestone or the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the Company’s performance subsequent to the inception of the arrangement to achieve the milestone, (b) relates solely to past performance, and (c) is reasonable relative to all of the deliverables and payment terms (including other potential milestone consideration) within the arrangement. See Note 3, “Collaboration Arrangements,” for analysis of milestone events deemed to be substantive or non-substantive.

Net_Income_Loss_Per_Common_Sha1

Net Income (Loss) Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Reconciliation of Numerator and Denominator	'
	A reconciliation of the numerator and denominator used in the calculation is as follows (in thousands, except per share amounts):
		Three Months Ended						Nine months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Numerator:
	Net income (loss) - basic	$	1,176		$	(991	)	$	(20,826	)	$	(99,523	)
	Less: noncash income from change in fair value of common stock warrants		(6,379	)		(2,967	)		(557	)		—
	Net loss - diluted		(5,203	)		(3,958	)		(21,383	)		(99,523	)
	Denominator:
	Weighted average common shares outstanding		58,542			55,654			57,362			53,516
	Dilutive effect of warrants		5,019			8,751			2,509			—
	Weighted-average common shares outstanding and potential dilutive common shares - diluted		63,561			64,405			59,871			53,516
	Net income (loss) per share
	Basic	$	0.02		$	(0.02	)	$	(0.36	)	$	(1.86	)
	Diluted	$	(0.08	)	$	(0.06	)	$	(0.36	)	$	(1.86	)
Warrants, Options and Purchase Rights Excluded from Computation of Diluted Net Loss Per Share	'
	The following outstanding warrants, options and purchase rights under the Company’s 2004 Employee Stock Purchase Plan were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an antidilutive effect. The amounts disclosed below are prior to the application of the treasury stock method (in thousands):
		Three Months  Ended						Nine months  Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Shares issuable upon exercise of warrants		—			—			4,034			11,726
	Shares issuable upon exercise of stock options		6,560			5,129			6,560			5,129
	Shares issuable related to the ESPP		28			48			28			48

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2013
Financial Liabilities Subject to Fair Value Measurements	'
	The following table sets forth the Company’s financial liabilities, related to warrants issued in the August 2008, October 2009 and March 2011 offerings, subject to fair value measurements as of September 30, 2013 and December 31, 2012:
	(in thousands)	Fair Value as of			Basis of Fair Value Measurements
		September 30,
		2013			Level 1			Level 2		Level 3
	August 2008 warrants	$	—		$	—		$	—	$	—
	October 2009 warrants		11,406			—			—		11,406
	March 2011 warrants		12,384			—			—		12,384
	Total common stock warrants	$	23,790		$	—		$	—	$	23,790
	(in thousands)	Fair Value as of			Basis of Fair Value Measurements
		December 31,
		2012			Level 1			Level 2		Level 3
	August 2008 warrants	$	8,014		$	—		$	—	$	8,014
	October 2009 warrants		11,963			—			—		11,963
	March 2011 warrants		12,581			—			—		12,581
	Total common stock warrants	$	32,558		$	—		$	—	$	32,558
Reconciliation of Warrant Liability Measured at Fair Value	'
	The following table is a reconciliation of the warrant liability measured at fair value using level 3 inputs (in thousands):
		Warrant Liability
	Balance at December 31, 2012	$	32,558
	Change in fair value of common stock warrants during nine months ended September 30, 2013		2,559
	Exercise of warrants during nine months ended September 30, 2013		(11,327	)
	Balance at September 30, 2013	$	23,790
October 2009 offering [Member]	'
Outstanding Warrants Valuation Assumption	'
		September 30,			December 31,
		2013			2012
	Risk-free interest rate		0.1	%		0.25	%
	Expected life (in years)		1.01			1.76
	Dividend yield		—			—
	Volatility		56	%		98	%
	Stock price	$	4.65		$	4.21
March 2011 offering [Member]	'
Outstanding Warrants Valuation Assumption	'
		September 30,			December 31,
		2013			2012
	Risk-free interest rate		0.63	%		0.72	%
	Expected life (in years)		2.46			3.21
	Dividend yield		—			—
	Volatility		87	%		94	%
	Stock price	$	4.65		$	4.21

Stock_Based_Compensation_Table

Stock Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock-Based Compensation Expense	'
	Stock-based compensation expense, which consists of the compensation cost for employee stock options and ESPP, and the value of options issued to non-employees for services rendered, was allocated to research and development and general and administrative in the unaudited condensed consolidated statements of operations as follows (in thousands):
		Three Months  Ended						Nine months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Amortization of stock-based compensation:
	Research and development	$	622		$	471		$	1,818		$	1,082
	General and administrative		609			473			1,738			1,005
		$	1,231		$	944		$	3,556		$	2,087
Weighted-Average Fair Value Valuation Assumptions	'
	The fair value of employee stock options and employee purchase rights under the Company’s ESPP was estimated using the following weighted-average assumptions for the three and nine months ended September 30, 2013 and 2012:
		Three Months Ended						Nine months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Employee Stock Options
	Risk-free interest rate		1.79	%		1.03	%		1.14	%		1.13	%
	Expected term (in years)		6.08			6.08			5.97			5.99
	Dividend yield		—			—			—			—
	Volatility		100	%		98	%		101	%		106	%
	Weighted-average fair value of stock options granted	$	4.21		$	5.87		$	4.04		$	5.12
		Three Months Ended						Nine months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Employee Stock Purchase Plan (ESPP):
	Risk-free interest rate		0.19	%		0.21	%		0.19	%		0.21	%
	Expected term (in years)		1.25			1.25			1.25			1.25
	Dividend yield		—			—			—			—
	Volatility		72	%		111	%		77	%		111	%
	Weighted-average fair value of ESPP purchase rights	$	2.22		$	4.62		$	2.27		$	3.46
Stock Option Activity Under Equity Incentive Plan	'
	The following table summarizes stock option activity under the Company’s 2004 Equity Incentive Plan:
	Options	Number of			Weighted-			Weighted-			Aggregate
		Shares			Average			Average			Intrinsic
					Exercise			Remaining			Value
					Price			Contractual
								Term
	Outstanding at December 31, 2012		5,098,972		$	3.18			—			—
	Granted		1,653,500		$	5.1			—			—
	Exercised		(127,153	)	$	1.59			—			—
	Forfeitures		(65,303	)	$	7.15			—			—
	Outstanding at September 30, 2013		6,560,016		$	3.66			7.83		$	10,534,778
	Vested and expected to vest September 30, 2013		6,504,707		$	3.64			7.82		$	10,518,742
	Exercisable at September 30, 2013		3,361,581		$	2.67			7.01		$	8,034,963

Fair_Value_Measurements_and_Ma1

Fair Value Measurements and Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Financial Assets at Fair Value on Recurring Basis	'
	The following table sets forth the Company’s financial assets (cash equivalents and marketable securities) at fair value on a recurring basis as of September 30, 2013 and December 31, 2012:
		Fair Value as of		Basis of Fair Value Measurements
		September 30,
	(in thousands)	2013		Level 1			Level 2			Level 3
	Money market funds	$	4,001	$	4,001		$	—		$	—
	Certificates of deposit		1,880		—			1,880			—
	Corporate debt securities		56,484		—			56,484			—
	U.S. Government securities		26,089		—			26,089			—
	Municipal securities		1,211		—			1,211			—
	Commercial paper		2,249		—			2,249			—
	Total cash equivalents and marketable securities	$	91,914	$	4,001		$	87,913		$	—
		Fair Value as of		Basis of Fair Value Measurements
		December 31,
	(in thousands)	2012		Level 1			Level 2			Level 3
	Money market funds	$	5,886	$	5,886		$	—		$	—
	Certificates of deposit		1,185		—			1,185			—
	Corporate debt securities		20,242		—			20,242			—
	U.S. Government securities		27,899		—			27,899			—
	Commercial paper		15,613		—			15,613			—
	Total cash equivalents and marketable securities	$	70,825	$	5,886		$	64,939		$	—
Summary of Company's Available-for-Sale Securities	'
	The Company invests in highly-liquid, investment-grade securities. The following is a summary of the Company’s available-for-sale securities at September 30, 2013 and December 31, 2012:
	As of September 30, 2013 (in thousands):	Cost Basis		Unrealized			Unrealized			Fair
				Gain			Loss			Value
	Money market funds	$	4,001	$	—		$	—		$	4,001
	Certificates of deposit		1,880		—			—			1,880
	Corporate debt securities		56,466		23			(5	)		56,484
	U.S. Government securities		26,071		19			(1	)		26,089
	Municipal securities		1,210		1			—			1,211
	Commercial paper		2,249		—			—			2,249
			91,877		43			(6	)		91,914
	Less cash equivalents		4,001		—			—			4,001
	Total marketable securities	$	87,876	$	43		$	(6	)	$	87,913
	As of December 31, 2012 (in thousands):	Cost Basis		Unrealized			Unrealized			Fair
				Gain			Loss			Value
	Money market funds	$	5,886	$	—		$	—		$	5,886
	Certificates of deposit		1,185		—			—			1,185
	Corporate debt securities		20,237		6			(1	)		20,242
	U.S. Government securities		27,893		12			(6	)		27,899
	Commercial paper		15,613		—			—			15,613
			70,814		18			(7	)		70,825
	Less cash equivalents		11,006		—			—			11,006
	Total marketable securities	$	59,808	$	18		$	(7	)	$	59,819
Marketable Securities with Unrealized Losses	'
	The following table provides the breakdown of the marketable securities with unrealized losses at September 30, 2013 (in thousands):
		In loss position for less
		than twelve months
	As of September 30, 2013 (in thousands):	Fair Value		Unrealized Loss
	U.S. Government securities	$	3,002	$	(1	)
	Corporate debt securities		17,435		(5	)
	Total marketable securities	$	20,437	$	(6	)

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Future Rental Payments Under Noncancelable Operating Leases	'
	The future rental payments required by the Company for all of its facilities under noncancelable operating leases are as follows (in thousands):
	Years Ending December 31,
	2013	$	161
	2014		651
	2015		674
	2016		702
	2017		238
	Total	$	2,426

Net_Income_Loss_Per_Common_Sha2

Net Income (Loss) Per Common Share - Reconciliation of Numerator and Denominator (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator:	'	'	'	'
Net income (loss) - basic	$1,176	($991)	($20,826)	($99,523)
Less: noncash income from change in fair value of common stock warrants	-6,379	-2,967	-557	'
Net loss - diluted	($5,203)	($3,958)	($21,383)	($99,523)
Denominator:	'	'	'	'
Weighted average common shares outstanding	58,542	55,654	57,362	53,516
Dilutive effect of warrants	5,019	8,751	2,509	'
Weighted-average common shares outstanding and potential dilutive common shares - diluted	63,561	64,405	59,871	53,516
Net income (loss) per share	'	'	'	'
Basic	$0.02	($0.02)	($0.36)	($1.86)
Diluted	($0.08)	($0.06)	($0.36)	($1.86)

Net_Income_Loss_Per_Common_Sha3

Net Income (Loss) Per Common Share - Warrants, Options and Purchase Rights Excluded from Computation of Diluted Net Loss Per Share (Detail)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Employee Stock Purchase Plan (ESPP) [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Shares issuable	28	48	28	48
Warrants [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Shares issuable	'	'	4,034	11,726
Employee Stock Options [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Shares issuable	6,560	5,129	6,560	5,129

Collaboration_Arrangements_Add

Collaboration Arrangements - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	14 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2013	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
					Merck KGaA [Member]	Merck KGaA [Member]	Merck KGaA [Member]	Merck KGaA [Member]	Merck KGaA [Member]	Merck KGaA [Member]
								Regulatory and development milestones [Member]	Regulatory and development milestones [Member]	Commercialization milestones [Member]
									2013 Potential Milestone payments [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]	'	'	'	'	'	'	'	'	'	'
Upfront payment received	'	'	'	'	'	$25	'	'	'	'
Milestone payments received to date	'	'	'	'	42.5	72.5	'	'	'	'
Potential future milestones	'	'	'	'	'	'	'	112.5	12.5	340
Merck's percentage share of worldwide development expenses	'	'	'	'	'	70.00%	'	'	'	'
Portion of profits that Company is eligible to participate in United States, depending upon total sales	'	'	'	'	'	50.00%	'	'	'	'
Revenue recognized by the Company	3.2	1.8	9.3	3.8	'	'	'	'	'	'
Collaboration payments achieved and received	'	'	'	'	30	'	97.5	'	'	'
Company earned a reimbursement for eligible worldwide development expenses	$5.50	$5	$11.60	$10	'	'	'	'	'	'

Stockholders_Equity_Additional

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

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

In Millions, except Share data, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Warrants [Member]

Cashless exercise of warrants [Member]

October 2009 offering [Member]

October 2009 offering [Member]

October 2009 offering [Member]

October 2009 offering [Member]

March 2011 offering [Member]

March 2011 offering [Member]

March 2011 offering [Member]

March 2011 offering [Member]

August 2008 offering [Member]

August 2008 offering [Member]

August 2008 offering [Member]

August 2008 offering [Member]

Warrants [Member]

Warrants [Member]

Warrants [Member]

Warrants [Member]

Warrants [Member]

Warrants [Member]

Warrants [Member]

Class of Warrant or Right [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Warrants exercised

'

'

893,475

2,367,636

'

'

'

'

'

'

'

'

'

'

'

'

Net proceeds from warrants exercised

'

$1.80

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock shares issued for cashless conversion of warrants

'

'

'

1,555,043

'

'

'

'

'

'

'

'

'

'

'

'

Reclassification of fair value from liability to permanent equity of warrants exercised

3.8

11.3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Warrants outstanding

8,300,000

8,300,000

'

'

4,287,940

4,287,940

'

'

4,033,783

4,236,083

'

'

0

3,058,811

'

'

Warrants expiration date

'

'

'

'

'

'

'

'

'

'

'

'

29-Aug-13

'

'

'

Change in fair value of common stock warrants

'

'

'

'

'

'

$2.80

$0.60

'

'

$2.90

$0.60

'

'

$0.60

$2.50

Stockholders_Equity_Outstandin

Stockholders' Equity - Outstanding Warrants Valuation Assumption (Detail) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
October 2009 offering [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Risk-free interest rate	0.10%	0.25%
Expected life (in years)	'1 year 4 days	'1 year 9 months 4 days
Dividend yield	'	'
Volatility	56.00%	98.00%
Stock price	$4.65	$4.21
March 2011 offering [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'	'
Risk-free interest rate	0.63%	0.72%
Expected life (in years)	'2 years 5 months 16 days	'3 years 2 months 16 days
Dividend yield	'	'
Volatility	87.00%	94.00%
Stock price	$4.65	$4.21

Stockholders_Equity_Financial_

Stockholders' Equity - Financial Liabilities Subject to Fair Value Measurements (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
August 2008 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	$8,014
October 2009 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	11,406	11,963
March 2011 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	12,384	12,581
Total common stock warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	23,790	32,558
Basis of Fair Value Measurements, Level 1 [Member] | August 2008 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	'
Basis of Fair Value Measurements, Level 1 [Member] | October 2009 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	'
Basis of Fair Value Measurements, Level 1 [Member] | March 2011 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	'
Basis of Fair Value Measurements, Level 1 [Member] | Total common stock warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	'
Basis of Fair Value Measurements, Level 2 [Member] | August 2008 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	'
Basis of Fair Value Measurements, Level 2 [Member] | October 2009 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	'
Basis of Fair Value Measurements, Level 2 [Member] | March 2011 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	'
Basis of Fair Value Measurements, Level 2 [Member] | Total common stock warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	'
Basis of Fair Value Measurements, Level 3 [Member] | August 2008 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	'	8,014
Basis of Fair Value Measurements, Level 3 [Member] | October 2009 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	11,406	11,963
Basis of Fair Value Measurements, Level 3 [Member] | March 2011 warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	12,384	12,581
Basis of Fair Value Measurements, Level 3 [Member] | Total common stock warrants [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Financial liabilities subject to fair value measurements	$23,790	$32,558

Stockholders_Equity_Reconcilia

Stockholders' Equity - Reconciliation of Warrant Liability Measured at Fair Value (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Equity [Abstract]	'	'	'	'
Beginning Balance	'	'	$32,558	'
Change in fair value of common stock warrants	-6,379	-2,967	2,559	85,572
Exercise of warrants	'	'	-11,327	'
Ending Balance	$23,790	'	$23,790	'

Stock_Based_Compensation_Stock

Stock Based Compensation - Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Amortization of stock-based compensation:	'	'	'	'
Stock-based compensation expense	$1,231	$944	$3,556	$2,087
Research and development [Member]	'	'	'	'
Amortization of stock-based compensation:	'	'	'	'
Stock-based compensation expense	622	471	1,818	1,082
General and administrative [Member]	'	'	'	'
Amortization of stock-based compensation:	'	'	'	'
Stock-based compensation expense	$609	$473	$1,738	$1,005

Stock_Based_Compensation_Weigh

Stock Based Compensation - Weighted-Average Fair Value Valuation Assumptions (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Employee Stock Purchase Plan (ESPP) [Member]	'	'	'	'
Weighted-average fair value valuation assumptions	'	'	'	'
Risk-free interest rate	0.19%	0.21%	0.19%	0.21%
Expected term (in years)	'1 year 3 months	'1 year 3 months	'1 year 3 months	'1 year 3 months
Dividend yield	'	'	'	'
Volatility	72.00%	111.00%	77.00%	111.00%
Weighted-average fair value of ESPP purchase rights	$2.22	$4.62	$2.27	$3.46
Employee Stock Options [Member]	'	'	'	'
Weighted-average fair value valuation assumptions	'	'	'	'
Risk-free interest rate	1.79%	1.03%	1.14%	1.13%
Expected term (in years)	'6 years 29 days	'6 years 29 days	'5 years 11 months 19 days	'5 years 11 months 27 days
Dividend yield	'	'	'	'
Volatility	100.00%	98.00%	101.00%	106.00%
Weighted-average fair value of stock options granted	$4.21	$5.87	$4.04	$5.12

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock-based compensation expense	$1,231,000	$944,000	$3,556,000	$2,087,000
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans	11,600,000	'	11,600,000	'
Unrecognized compensation cost related to unvested stock-based awards granted to employees under the stock option plans, period for recognition	'	'	'2 years 6 months	'
Non-employee stock-based compensation expense	36,000	100,000	100,000	200,000
Total intrinsic value of stock options exercised	'	'	500,000	1,400,000
Cash received from stock option exercises	'	'	200,000	400,000
Amount withheld by plan participants to purchase stock	100,000	'	100,000	'
2004 Equity Incentive Plan [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Additional shares authorized for issuance	'	'	1,250,000	'
Shares authorized and available for issuance	160,214	'	160,214	'
Employee stock-based compensation expense [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock-based compensation expense	$1,200,000	$800,000	$3,500,000	$1,900,000
2004 Employee Stock Purchase Plan [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Additional shares authorized for issuance	'	'	100,000	'
Shares authorized and available for issuance	235,896	'	235,896	'
Plan participants purchased shares	'	'	167,245	'
Average purchase price under 2004 Employee Stock Purchase Plan	$1.69	'	$1.69	'

Stock_Based_Compensation_Stock1

Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Number of Shares, Outstanding at December 31, 2012	5,098,972
Number of Shares, Granted	1,653,500
Number of Shares, Exercised	-127,153
Number of Shares, Forfeitures	-65,303
Number of Shares, Outstanding at September 30, 2013	6,560,016
Number of Shares, Vested and expected to vest September 30, 2013	6,504,707
Number of Shares, Exercisable at September 30, 2013	3,361,581
Weighted-Average Exercise Price, Outstanding at December 31, 2012	$3.18
Weighted-Average Exercise Price, Granted	$5.10
Weighted-Average Exercise Price, Exercised	$1.59
Weighted-Average Exercise Price, Forfeitures	$7.15
Weighted-Average Exercise Price, Outstanding at September 30, 2013	$3.66
Weighted-Average Exercise Price, Vested and expected to vest September 30, 2013	$3.64
Weighted-Average Exercise Price, Exercisable at September 30, 2013	$2.67
Weighted-Average Remaining Contractual Term, Outstanding at September 30, 2013	'7 years 9 months 29 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest September 30, 2013	'7 years 9 months 26 days
Weighted-Average Remaining Contractual Term, Exercisable at September 30, 2013	'7 years 4 days
Aggregate Intrinsic Value, Outstanding at September 30, 2013	$10,534,778
Aggregate Intrinsic Value, Vested and expected to vest September 30, 2013	10,518,742
Aggregate Intrinsic Value, Exercisable at September 30, 2013	$8,034,963

Fair_Value_Measurements_and_Ma2

Fair Value Measurements and Marketable Securities - Financial Assets at Fair Value on Recurring Basis (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	$91,914	$70,825
Money market funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	4,001	5,886
Certificates of deposit [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	1,880	1,185
Corporate debt securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	56,484	20,242
U.S. Government securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	26,089	27,899
Municipal securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	1,211	'
Commercial paper [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	2,249	15,613
Basis of Fair Value Measurements, Level 1 [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	4,001	5,886
Basis of Fair Value Measurements, Level 1 [Member] | Money market funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	4,001	5,886
Basis of Fair Value Measurements, Level 1 [Member] | Certificates of deposit [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 1 [Member] | Corporate debt securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 1 [Member] | U.S. Government securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 1 [Member] | Municipal securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 1 [Member] | Commercial paper [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 2 [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	87,913	64,939
Basis of Fair Value Measurements, Level 2 [Member] | Money market funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 2 [Member] | Certificates of deposit [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	1,880	1,185
Basis of Fair Value Measurements, Level 2 [Member] | Corporate debt securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	56,484	20,242
Basis of Fair Value Measurements, Level 2 [Member] | U.S. Government securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	26,089	27,899
Basis of Fair Value Measurements, Level 2 [Member] | Municipal securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	1,211	'
Basis of Fair Value Measurements, Level 2 [Member] | Commercial paper [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	2,249	15,613
Basis of Fair Value Measurements, Level 3 [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 3 [Member] | Money market funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 3 [Member] | Certificates of deposit [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 3 [Member] | Corporate debt securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 3 [Member] | U.S. Government securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 3 [Member] | Municipal securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'
Basis of Fair Value Measurements, Level 3 [Member] | Commercial paper [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Total cash equivalents and marketable securities	'	'

Fair_Value_Measurements_and_Ma3

Fair Value Measurements and Marketable Securities - Summary of Company's Available-for-Sale Securities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	$87,876	$59,808
Unrealized Gain	43	18
Unrealized Loss	-6	-7
Fair Value	87,913	59,819
Money market funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	4,001	5,886
Unrealized Gain	'	'
Unrealized Loss	'	'
Fair Value	4,001	5,886
Certificates of deposit [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	1,880	1,185
Unrealized Gain	'	'
Unrealized Loss	'	'
Fair Value	1,880	1,185
Corporate debt securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	56,466	20,237
Unrealized Gain	23	6
Unrealized Loss	-5	-1
Fair Value	56,484	20,242
U.S. Government securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	26,071	27,893
Unrealized Gain	19	12
Unrealized Loss	-1	-6
Fair Value	26,089	27,899
Municipal securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	1,210	'
Unrealized Gain	1	'
Unrealized Loss	'	'
Fair Value	1,211	'
Commercial paper [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	2,249	15,613
Unrealized Gain	'	'
Unrealized Loss	'	'
Fair Value	2,249	15,613
Marketable securities including cash equivalents [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	91,877	70,814
Unrealized Gain	43	18
Unrealized Loss	-6	-7
Fair Value	91,914	70,825
Less cash equivalents [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost Basis	4,001	11,006
Unrealized Gain	'	'
Unrealized Loss	'	'
Fair Value	$4,001	$11,006

Fair_Value_Measurements_and_Ma4

Fair Value Measurements and Marketable Securities - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2013
Schedule of Available-for-sale Securities [Line Items]	'
Weighted average maturity for available for sale securities	'7 months
Shares of common stock to be purchased with warrants	8,300,000
Maximum [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Available for sale securities, longest maturity date	'2015-05

Fair_Value_Measurements_and_Ma5

Fair Value Measurements and Marketable Securities - Marketable Securities with Unrealized Losses (Detail) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'
Marketable securities, In loss position for less than twelve months, Fair Value	$20,437
Marketable securities, In loss position for less than twelve months, Unrealized Loss	-6
U.S. Government securities [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Marketable securities, In loss position for less than twelve months, Fair Value	3,002
Marketable securities, In loss position for less than twelve months, Unrealized Loss	-1
Corporate debt securities [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Marketable securities, In loss position for less than twelve months, Fair Value	17,435
Marketable securities, In loss position for less than twelve months, Unrealized Loss	($5)

Commitments_and_Contingencies_1

Commitments and Contingencies - Future Rental Payments Under Noncancelable Operating Leases (Detail) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Leases [Abstract]	'
2013	$161
2014	651
2015	674
2016	702
2017	238
Total	$2,426