Infinity Pharmaceuticals (INFIQ) 10-Q 7 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013
Document Information [Line Items]	'
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	'INFI
Entity Registrant Name	'INFINITY PHARMACEUTICALS, INC.
Entity Central Index Key	'0001113148
Current Fiscal Year End Date	'--12-31
Entity Filer Category	'Accelerated Filer
Entity Common Stock, Shares Outstanding	48,086,619

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets	'	'
Cash and cash equivalents	$53,478	$175,742
Available-for-sale securities	196,825	150,276
Prepaid expenses and other current assets	4,701	3,731
Total current assets	255,004	329,749
Property and equipment, net	4,089	4,079
Long-term available-for-sale securities	554	617
Restricted cash	1,129	1,128
Other assets	36	87
Total assets	260,812	335,660
Liabilities and stockholders' equity	'	'
Accounts payable	5,010	2,148
Accrued expenses	11,913	10,059
Due to Millennium, current	6,613	6,456
Total current liabilities	23,536	18,663
Due to Millennium, less current portion	6,405	6,252
Other liabilities	611	540
Total liabilities	30,552	25,455
Commitments and contingencies	'	'
Stockholders' equity:	'	'
Preferred Stock, $.001 par value; 1,000,000 shares authorized; no shares issued and outstanding at September 30, 2013 and December 31, 2012	'	'
Common Stock, $.001 par value; 100,000,000 shares authorized; 48,086,619 and 47,499,257 shares issued and outstanding at September 30, 2013 and December 31, 2012, respectively	48	48
Additional paid-in capital	646,919	633,039
Accumulated deficit	-416,871	-323,016
Accumulated other comprehensive income	164	134
Total stockholders' equity	230,260	310,205
Total liabilities and stockholders' equity	$260,812	$335,660

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common Stock, par value	$0.00	$0.00
Common Stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	48,086,619	47,499,257
Common Stock, shares outstanding	48,086,619	47,499,257

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations and Comprehensive Income (loss) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Collaborative research and development revenue from Purdue entities	'	'	'	$47,114
Operating expenses:	'	'	'	'
Research and development	26,857	21,495	73,168	78,578
General and administrative	7,319	6,294	21,424	20,771
Total operating expenses	34,176	27,789	94,592	99,349
Gain on termination of Purdue entities alliance	'	46,555	'	46,555
Income (loss) from operations	-34,176	18,766	-94,592	-5,680
Other income (expense):	'	'	'	'
Interest expense	'	-533	'	-1,908
Income from Massachusetts tax incentive award	'	'	'	193
Investment and other income	238	170	737	416
Total other income (expense)	238	-363	737	-1,299
Net income (loss)	-33,938	18,403	-93,855	-6,979
Earnings (loss) per common share:	'	'	'	'
Basic	($0.71)	$0.57	($1.96)	($0.24)
Diluted	($0.71)	$0.52	($1.96)	($0.24)
Weighted average number of common shares outstanding:	'	'	'	'
Basic	48,052,939	32,039,866	47,875,706	28,638,512
Diluted	48,052,939	35,173,223	47,875,706	28,638,512
Other comprehensive income (loss):	'	'	'	'
Net unrealized holding gains on available-for-sale securities arising during the period	117	43	30	87
Comprehensive income (loss)	($33,821)	$18,446	($93,825)	($6,892)

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Operating activities	'	'
Net loss	($93,855)	($6,979)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation	1,336	1,257
Stock-based compensation, including 401(k) match	9,335	5,082
Net amortization of available-for-sale securities	1,570	1,069
Impairment of property and equipment	'	121
Non-cash interest expense on long-term debt due to Purdue entities	'	1,908
Non-cash interest expense on amount due to Millennium	310	'
Other, net	-2	41
Changes in operating assets and liabilities:	'	'
Unbilled accounts receivable	'	218
Prepaid expenses and other assets	-919	-1,200
Accounts payable, accrued expenses and other liabilities	4,787	-6,678
Deferred revenue from Purdue entities	'	-38,887
Net cash used in operating activities	-77,438	-44,048
Investing activities	'	'
Purchases of property and equipment	-1,346	-667
Purchases of available-for-sale securities	-230,599	-133,852
Proceeds from sales of available-for-sale securities	1,031	6,281
Proceeds from maturities of available-for-sale securities	181,543	81,837
Net cash used in investing activities	-49,371	-46,401
Financing activities	'	'
Proceeds from issuances of common stock related to stock offering, net	'	82,800
Proceeds from issuances of common stock to Purdue entities	'	27,500
Proceeds from issuances of common stock related to stock incentive plans	4,545	8,869
Net cash provided by financing activities	4,545	119,169
Net increase (decrease) in cash and cash equivalents	-122,264	28,720
Cash and cash equivalents at beginning of period	175,742	24,197
Cash and cash equivalents at end of period	53,478	52,917
Supplemental schedule of noncash investing and financing activities	'	'
Issuance of common stock to extinguish debt from Purdue entities	'	$51,277

Organization

Organization	9 Months Ended
	Sep. 30, 2013
Organization	'
	1. Organization
	Infinity Pharmaceuticals, Inc. is an innovative drug discovery and development company seeking to discover, develop and deliver to patients best-in-class medicines designed to address difficult-to-treat diseases. As used throughout these unaudited, condensed consolidated financial statements, the terms “Infinity,” “we,” “us,” and “our” refer to the business of Infinity Pharmaceuticals, Inc. and its wholly owned subsidiary.

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2013
Basis of Presentation	'
	2. Basis of Presentation
	These condensed consolidated financial statements include the accounts of Infinity and its wholly owned subsidiary. We have eliminated all significant intercompany accounts and transactions in consolidation.
	These condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring accruals and revisions of estimates, considered necessary for a fair presentation of the condensed consolidated financial statements have been included. Interim results for the three and nine months ended September 30, 2013 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2013.
	The information presented in the condensed consolidated financial statements and related footnotes at September 30, 2013, and for the three and nine months ended September 30, 2013 and 2012, is unaudited, and the condensed consolidated balance sheet amounts and related footnotes at December 31, 2012 have been derived from our audited financial statements. For further information, please refer to the consolidated financial statements and accompanying footnotes included in our annual report on Form 10-K for the fiscal year ended December 31, 2012, which was filed with the U.S. Securities and Exchange Commission on March 5, 2013.

Significant_Accounting_Policie

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2013
Significant Accounting Policies	'
	3. Significant Accounting Policies
	Cash Equivalents and Available-For-Sale Securities
	Cash equivalents and available-for-sale securities primarily consist of money market funds, U.S. government-sponsored enterprise obligations, corporate obligations, U.S. treasury securities and mortgage-backed securities. Corporate obligations include obligations issued by corporations in countries other than the United States, including some obligations that have not been guaranteed by governments and government agencies. We consider all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents. Cash equivalents, which consist of money market funds and corporate obligations, are stated at fair value. They are also readily convertible to known amounts of cash and have such short-term maturities that each presents insignificant risk of change in value due to changes in interest rates. Our classification of cash equivalents is consistent with prior periods.
	We determine the appropriate classification of marketable securities at the time of purchase and reevaluate such designation at each balance sheet date. We have classified all of our marketable securities at September 30, 2013 and December 31, 2012 as “available-for-sale.” We carry available-for-sale securities at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity.
	We adjust the cost of available-for-sale debt securities for amortization of premiums and accretion of discounts to maturity. We include such amortization and accretion in interest and investment income. The cost of securities sold is based on the specific identification method. We include in investment income interest and dividends on securities classified as available-for-sale.
	We conduct periodic reviews to identify and evaluate each investment that is in an unrealized loss position in order to determine whether an other-than-temporary impairment exists. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. Unrealized losses on available-for-sale debt securities that are determined to be temporary, and not related to credit loss, are recorded, net of tax, in accumulated other comprehensive income (loss).
	For available-for-sale debt securities in an unrealized loss position, we perform an analysis to assess whether we intend to sell or whether we would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. Where we intend to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary, and the full amount of the unrealized loss is recorded within earnings as an impairment loss.
	Regardless of our intent to sell a security, we perform additional analysis on all securities in an unrealized loss position to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where we do not expect to receive cash flows sufficient to recover the amortized cost basis of a security and are recorded within earnings as an impairment loss.
	Segment Information
	We operate in one business segment, which focuses on drug discovery and development. We make operating decisions based upon performance of the enterprise as a whole and utilize our consolidated financial statements for decision making.
	All of our revenues to date have been generated under research collaboration agreements. Revenue associated with the amortization of the deferred revenue associated with the grant of rights and licenses to, and reimbursed research and development services provided to, Mundipharma International Corporation Limited (Mundipharma), and Purdue Pharmaceutical Products L.P. (Purdue), accounted for all of our revenue for the nine months ended September 30, 2012. We considered Mundipharma, Purdue and their respective associated entities to be related parties for financial reporting purposes because of their equity ownership prior to April 2013 (see note 7).
	Basic and Diluted Loss per Common Share
	Basic net loss per share is based upon the weighted average number of common shares outstanding during the period. Diluted net loss per share is based upon the weighted average number of common shares outstanding during the period plus the effect of additional weighted average common equivalent shares outstanding during the period when the effect of adding such shares is dilutive. Common equivalent shares result from the assumed exercise of outstanding stock options (the proceeds of which are then assumed to have been used to repurchase outstanding stock using the treasury stock method). In addition, the assumed proceeds under the treasury stock method include the average unrecognized compensation expense of stock options that are in-the-money. This results in the “assumed” buyback of additional shares, thereby reducing the dilutive impact of stock options. Common equivalent shares have not been included in the net loss per share calculations for the periods presented because the effect of including them would have been anti-dilutive. Total potential gross common equivalent shares consisted of the following:
			At September 30,
			2013			2012
	Stock options			6,255,772			7,113,072
	Warrants			—			136,655
	Basic and diluted earnings (loss) per common share were determined as follows:
			Three Months Ended					Nine Months Ended
			September 30,					September 30,
			2013			2012		2013			2012
			(in thousands, except share and per share amounts)
	Basic
	Net income (loss)		$	(33,938	)	$	18,403	$	(93,855	)	$	(6,979	)
	Weighted average common shares outstanding			48,052,939			32,039,866		47,875,706			28,638,512
	Basic earnings (loss) per common share		$	(0.71	)	$	0.57	$	(1.96	)	$	(0.24	)
	Diluted
	Net income (loss)		$	(33,938	)	$	18,403	$	(93,855	)	$	(6,979	)
	Weighted average common shares outstanding			48,052,939			32,039,866		47,875,706			28,638,512
	Effect of dilutive options			—			3,133,357		—			—
	Weighted average common shares outstanding assuming dilution			48,052,939			35,173,223		47,875,706			28,638,512
	Diluted earnings (loss) per common share		$	(0.71	)	$	0.52	$	(1.96	)	$	(0.24	)
	Comprehensive Loss
	Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) is comprised of unrealized holding gains and losses arising during the period on available-for-sale securities that are not other-than-temporarily impaired. During the nine months ended September 30, 2013, there were no reclassifications out of accumulated other comprehensive income (loss).
	Stock-Based Compensation Expense
	For awards granted to employees and directors, including our Employee Stock Purchase Plan (“ESPP”), we measure stock-based compensation cost at the grant date based on the estimated fair value of the award and recognize it as expense over the requisite service period on a straight-line basis. The ESPP permits eligible employees to purchase shares of our common stock at a discount and consists of consecutive, overlapping 24-month offering periods, each consisting of four six-month purchase periods. On the first day of each offering period, each employee who is enrolled in the ESPP will automatically receive an option to purchase up to a whole number of shares of our common stock. The purchase price of each of the shares purchased in a given purchase period will be 85% of the closing price of a share of our common stock on the first day of the offering period or the last day of the purchase period, whichever is lower. We record the expense of services rendered by non-employees based on the estimated fair value of the stock option as of the respective vesting date. We use the Black-Scholes valuation model in determining the fair value of all equity awards. We have no awards with market or performance conditions.
	Revenue Recognition
	To date, all of our revenue has been generated under research collaboration agreements. The terms of these research collaboration agreements may include payment to us of non-refundable, up-front license fees, funding or reimbursement of research and development efforts, milestone payments if specified objectives are achieved, and/or royalties on product sales. We recognize revenue based upon our best estimate of the selling price for an undelivered item when there is no other means to determine the fair value of that undelivered item.
	Under our previous strategic alliance with Mundipharma and Purdue, we recognized revenues from non-refundable, up-front license fees on a straight-line basis over the contracted or estimated period of performance, which was the research and development term. We regularly considered whether events warranted a change in the estimated period of performance under an agreement. Such a change would have caused us to modify the period of time over which we recognized revenue from the up-front license fee on a prospective basis and would have, in turn, resulted in changes in our quarterly and annual results. We recognized research and development funding as earned over the period of effort as related research and development costs were incurred in proportion to our forecasted total expenses as compared to the total expected research and development funding for the year. We recognized the impact of any change in forecasted total expenses or expected research and development funding as a change in accounting estimate and recorded the impact of that change on a prospective basis. On July 17, 2012, we mutually agreed with Mundipharma and Purdue to terminate our strategic alliance agreements. Further information regarding the terms and conditions of this termination is described below under note 7.
	At the inception of each agreement that includes milestone payments, we evaluate whether each milestone is substantive on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether:
		•		the consideration is commensurate with either (1) our performance to achieve the milestone, or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from our performance to achieve the milestone,
		•		the consideration relates solely to past performance, and
		•		the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement.
	We evaluate factors such as the clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment. We recognize revenues related to substantive milestones in full in the period in which the substantive milestone is achieved. If a milestone payment is not considered substantive, we recognize the applicable milestone over the remaining period of performance. Our strategic alliance with Mundipharma and Purdue did not include potential milestone payments.
	We will recognize royalty revenue, if any, based upon actual and estimated net sales by the licensee of licensed products in licensed territories in the period the sales occur. We have not recognized any royalty revenue to date.
	Research and Development Expense
	Research and development expense consists of expenses incurred in performing research and development activities, including salaries and benefits, overhead expenses including facilities expenses, materials and supplies, preclinical expenses, clinical trial and related clinical manufacturing expenses, stock-based compensation expense, depreciation of equipment, contract services, and other outside expenses. We also include as research and development expense up-front license payments related to acquired technologies which have not yet reached technological feasibility and have no alternative use. We expense research and development costs as they are incurred. We capitalize nonrefundable advance payments related to research and development activities and expense the payments as the related goods are delivered or the related services are performed. We have been a party to collaboration agreements in which we were reimbursed for work performed on behalf of the collaborator, as well as one in which we reimbursed the collaborator for work it had performed. We record all appropriate expenses under our collaborations as research and development expense. If the arrangement provides for reimbursement of research and development expenses, as was the case with our alliance with Mundipharma and Purdue, we record the reimbursement as revenue. If the arrangement provides for us to reimburse the collaborator for research and development expenses or achieving a development milestone for which a payment is due, as was the case with our agreement with Intellikine, Inc. (Intellikine), we record the reimbursement or the achievement of the development milestone as research and development expense. In January 2012, Intellikine was acquired by Takeda Pharmaceutical Company Limited (Takeda) acting through its Millennium business unit.
	Income Taxes
	We use the liability method to account for income taxes. Deferred tax assets and liabilities are determined based on differences between financial reporting and income tax basis of assets and liabilities, as well as net operating loss and tax credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when the differences reverse. Deferred tax assets are reduced by a valuation allowance to reflect the uncertainty associated with their ultimate realization. The effect of a change in tax rate on deferred taxes is recognized in income or loss in the period that includes the enactment date.
	We use our judgment for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We recognize any material interest and penalties related to unrecognized tax benefits in income tax expense.
	Due to the uncertainty surrounding the realization of the net deferred tax assets in future periods, we have recorded a full valuation allowance against our otherwise recognizable net deferred tax assets as of September 30, 2013 and December 31, 2012.
	Fair Value Measurements
	We define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We determine fair value based on the assumptions market participants use when pricing the asset or liability. We also use the fair value hierarchy that prioritizes the information used to develop these assumptions.
	We value our available-for-sale securities utilizing third party pricing services. The pricing services use many observable market inputs to determine value, including benchmark yields, reportable trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, new issue data, monthly payment information and collateral performance. We validate the prices provided by our third party pricing services by understanding the models used, obtaining market values from other pricing sources, and confirming that those securities trade in active markets.
	We value the balance of the release payment due to Millennium based on a discounted cash flow model.
	Property and Equipment
	Property and equipment are stated at cost. Depreciation is recorded using the straight-line method over the estimated useful lives of the applicable assets. Application development costs incurred for computer software developed or obtained for internal use are capitalized. Upon sale or retirement, the cost and related accumulated depreciation are eliminated from the respective account, and the resulting gain or loss, if any, is included in current operations. Amortization of leasehold improvements and capital leases are included in depreciation expense. Repairs and maintenance charges that do not increase the useful life of the assets are charged to operations as incurred. Property and equipment are depreciated over the following periods:
	Laboratory equipment		5 years
	Computer equipment and software		3 to 5 years
	Leasehold improvements		Shorter of lease term or useful life of asset
	Furniture and fixtures		7 years

StockBased_Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2013
Stock-Based Compensation	'
	4. Stock-Based Compensation
	Total stock-based compensation expense, related to all equity awards, for the three and nine months ended September 30, 2013 and 2012 comprised the following:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
		(in thousands)
	Effect of stock-based compensation on net loss by line item:
	Research and development	$	1,599		$	772		$	4,618		$	2,371
	General and administrative		1,660			995			4,717			2,711
	As of September 30, 2013, we had approximately $22.8 million of total unrecognized compensation cost, net of estimated forfeitures, related to unvested stock options and awards under our ESPP, which are expected to be recognized over a weighted-average period of 2.9 years.
	During the nine months ended September 30, 2013, options to purchase 534,284 shares of common stock were exercised, with a weighted-average exercise price of $8.51.
	During the nine months ended September 30, 2013, we granted options to purchase 1,371,094 shares of our common stock at a weighted-average fair value of $18.35 and a weighted-average exercise price of $33.09. During the nine months ended September 30, 2012, we granted options to purchase 1,697,913 shares of our common stock at a weighted-average fair value of $5.97 and a weighted-average exercise price of $10.34. For the three and nine months ended September 30, 2013 and 2012, the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Risk-free interest rate		1.3	%		0.8	%		0.9	%		1.1	%
	Expected annual dividend yield		—			—			—			—
	Expected stock price volatility		71.3	%		62.6	%		63.2	%		63.3	%
	Expected term of options		4.7 years			6.2 years			4.9 years			6.1 years

Cash_Cash_Equivalents_and_Avai

Cash, Cash Equivalents and Available-for-Sale Securities	9 Months Ended
	Sep. 30, 2013
Cash, Cash Equivalents and Available-for-Sale Securities	'
	5. Cash, Cash Equivalents and Available-for-Sale Securities
	The following is a summary of cash, cash equivalents and available-for-sale securities:
		September 30, 2013
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	53,478	$	—	$	—		$	53,478
	Available-for-sale securities:
	Corporate obligations due in one year or less		116,871		51		(20	)		116,902
	Corporate obligations due in one to five years		18,574		37		—			18,611
	Mortgage-backed securities due after ten years		489		65		—			554
	U.S. government-sponsored enterprise obligations due in one year or less		22,004		8		—			22,012
	U.S. government-sponsored enterprise obligations due in one to five years		39,277		23		—			39,300
	Total available-for-sale securities		197,215		184		(20	)		197,379
	Total cash, cash equivalents and available-for- sale securities	$	250,693	$	184	$	(20	)	$	250,857
		December 31, 2012
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	175,742	$	—	$	—		$	175,742
	Available-for-sale securities:
	Corporate obligations due in one year or less		88,644		53		(13	)		88,684
	Corporate obligations due in one to five years		16,291		8		(9	)		16,290
	Mortgage-backed securities due after ten years		547		70		—			617
	U.S. government-sponsored enterprise obligations due in one year or less		38,779		22		—			38,801
	U.S. government-sponsored enterprise obligations due in one to five years		6,498		3		—			6,501
	Total available-for-sale securities		150,759		156		(22	)		150,893
	Total cash, cash equivalents and available-for-sale securities	$	326,501	$	156	$	(22	)	$	326,635
	We held 11 debt securities at September 30, 2013 that had been in an unrealized loss position for less than 12 months. The fair value of these securities was $38.7 million. We evaluated our securities for other-than-temporary impairments based on quantitative and qualitative factors. We considered the decline in market value for these 11 securities to be primarily attributable to current economic and market conditions. It is not more likely than not that we will be required to sell these securities, and we do not intend to sell these securities before the recovery of their amortized cost bases, which recovery is expected within the next 12 months. Based on our analysis, we do not consider these investments to be other-than-temporarily impaired as of September 30, 2013.
	As of September 30, 2013, we held 21 financial institution debt securities and other corporate debt securities located in Switzerland, Canada, Australia, the United Kingdom, the Netherlands, Japan and France, and with a fair value of $87.5 million. Five of these securities, which were issued by Switzerland, the Netherlands, Australia, Japan and the United Kingdom, had gross unrealized losses of $14 thousand and a fair value of $17.6 million. These securities are short-term in nature and are scheduled to mature within 12 months. Based on our analysis, we do not consider these investments to be other-than-temporarily impaired as of September 30, 2013.
	We had no material realized gains or losses on our available-for-sale securities for the three and nine months ended September 30, 2013 and 2012. There were no other-than-temporary impairments recognized for the three and nine months ended September 30, 2013 and 2012.

Fair_Value

Fair Value	9 Months Ended
	Sep. 30, 2013
Fair Value	'
	6. Fair Value
	We use a valuation hierarchy for disclosure of the inputs used to measure fair value. This hierarchy prioritizes the inputs into three broad levels. Level 1 inputs, which we consider the highest level inputs, are quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. Level 3 inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value. For our fixed income securities, we reference pricing data supplied by our custodial agent and nationally known pricing vendors, using a variety of daily data sources, largely readily-available market data and broker quotes. We validate the prices provided by our third party pricing services by reviewing their pricing methods and obtaining market values from other pricing sources. After completing our validation procedures, we did not adjust or override any fair value measurements provided by our pricing services as of September 30, 2013 and December 31, 2012.
	The following table provides the assets carried at fair value measured on a recurring basis as of September 30, 2013:
			Level 1		Level 2
			(in thousands)
	Cash and cash equivalents		$	44,876	$	8,602
	Corporate obligations (including commercial paper)			—		135,513
	Mortgage-backed securities			—		554
	U.S. government-sponsored enterprise obligations			—		61,312
	Total		$	44,876	$	205,981
	The fair value of the available-for-sale securities and cash and cash equivalents (including asset types listed below with maturities of three months or less at the time of purchase) is based on the following inputs:
		•		Corporate Obligations:
		•		Commercial paper: calculations by custodian based on three month Treasury bill published on last business day of the month.
		•		Other: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data.
		•		Mortgage-backed securities: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data, new issue data, monthly payment information and collateral performance.
		•		U.S. government-sponsored enterprise obligations: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data.
	The amount due to Millennium is recorded at its carrying value at September 30, 2013. The fair value of the amount due to Millennium, a Level 2 measurement, was approximately $13.1 million as of September 30, 2013 and was determined using a discounted cash flow model and based on an interest rate we would be charged for a similar loan as of September 30, 2013 (see note 7).
	The carrying amounts reflected in the consolidated balance sheets for prepaid expenses and other current assets, other assets, accounts payable and accrued expenses approximate fair value due to their short term maturities.
	There have been no changes to the valuation methods during the nine months ended September 30, 2013. We evaluate transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between Level 1 and Level 2 during the nine months ended September 30, 2013. We had no available-for-sale securities that were classified as Level 3 at any point during the nine months ended September 30, 2013 or during the year ended December 31, 2012.

Collaborations

Collaborations	9 Months Ended
	Sep. 30, 2013
Collaborations	'
	7. Collaborations
	Millennium
	In July 2010, we entered into a development and license agreement with Intellikine under which we obtained rights to discover, develop and commercialize pharmaceutical products targeting the delta and/or gamma isoforms of PI3K, including IPI-145, and paid Intellikine a $13.5 million up-front license fee. In January 2012, Intellikine was acquired by Takeda acting through its Millennium business unit. We refer to our PI3K program licensor as Millennium. In December 2012, we amended and restated our development and license agreement with Millennium.
	Under the terms of the amended and restated agreement, we retained our worldwide development and commercialization rights for products arising from the agreement for all therapeutic indications. We and Millennium no longer conduct the collaborative research program, and the restrictions on each party’s ability to research, develop and commercialize products directed to the delta and/or gamma isoforms of PI3K that meet certain selectivity criteria have terminated, subject, in the case of Millennium, to the exclusive licenses granted to us under the amended and restated agreement.
	Additionally, under the amended and restated agreement, Millennium waived the option it had under the original agreement to convert, upon payment of an option fee, its royalty interest in U.S. sales of PI3K products and its right to receive certain milestone payments with respect to such products into the right to share in 50 percent of profits and losses on U.S. development and commercialization of those PI3K products for which the first Phase 2 clinical trial, as defined in the original agreement, was conducted in an oncology indication, and to participate in up to 30 percent of the detailing effort for these products in the United States. In consideration of such waiver, we agreed to pay to Millennium $15 million, payable in installments. During the year ended December 31, 2012, we paid $1.7 million of the $15 million, and we recorded the $15 million release payment at its fair value of $14.4 million in research and development expenses. The remaining amount is payable in two equal payments due in January 2014 and January 2015, which we recorded as short-term and long-term liabilities due to Millennium on our balance sheet.
	In addition to developing IPI-145, we are seeking to develop our second potent, oral PI3K-delta,gamma inhibitor, IPI-443, and we are seeking to identify additional novel inhibitors of PI3K-delta and/or PI3K-gamma for future development. We are obligated to pay to Millennium up to $15 million in remaining success-based milestone payments for the development of two distinct product candidates, of which we expect to pay a $10 million milestone payment in the fourth quarter of 2013 in connection with the initiation of our Phase 3 study of IPI-145 in patients with relapsed or refractory CLL. We are also obligated to pay up to $450 million in success-based milestones for the approval and commercialization of two distinct products. As a result of the amendment, such products may include products we license in from a third party. In addition, we are obligated to pay Millennium tiered royalties on worldwide net sales ranging from 7 percent to 11 percent, which are the same royalty levels as those specified under the original agreement, upon successful commercialization of products described in the agreement. Such royalties are payable until the later to occur of the expiration of specified patent rights and the expiration of non-patent regulatory exclusivities in a country, subject to reduction, and limits on the number of products, in certain circumstances.
	The amended and restated agreement expires on the later of the expiration of certain patents and the expiration of the royalty payment terms for the products, unless earlier terminated. Either party may terminate the agreement on 75 days’ prior written notice if the other party materially breaches the agreement and fails to cure such breach within the applicable notice period, provided that the notice period is reduced to 30 days where the alleged breach is non-payment. Millennium may also terminate the agreement if we are not diligent in developing or commercializing the licensed products and do not, within three months after notice from Millennium, demonstrate to Millennium’s reasonable satisfaction that we have not failed to be diligent. The foregoing periods are subject to extension in certain circumstances. Additionally, Millennium may terminate the agreement upon 30 days’ prior written notice if we or a related party bring an action challenging the validity of any of the licensed patents, provided that we have not withdrawn such action before the end of the 30-day notice period. We may terminate the agreement at any time upon 180 days’ prior written notice. The agreement also provides for customary reciprocal indemnification obligations of the parties.
	Mundipharma and Purdue
	Strategic Alliance Termination Agreements
	On July 17, 2012, we terminated our strategic alliance with Mundipharma and Purdue and entered into termination and revised relationship agreements with each of those entities, which we refer to as the 2012 termination agreements. The alliance was previously governed by strategic alliance agreements that we entered into with each of Mundipharma and Purdue in November 2008. The strategic alliance agreement with Purdue was focused on the development and commercialization in the United States of products targeting fatty acid amide hydrolase (FAAH). The strategic alliance agreement with Mundipharma was focused on the development and commercialization outside of the United States of all products and product candidates that inhibit or target the Hedgehog pathway, FAAH, PI3K, and product candidates arising out of our early discovery projects in all disease fields. Our heat shock protein 90 (Hsp90) program was expressly excluded from the alliance.
	Under the terms of the 2012 termination agreements:
		•	All intellectual property rights that we had previously licensed to Mundipharma and Purdue to develop and commercialize products under the previous strategic alliance agreements terminated, with the result that we have worldwide rights to all product candidates that had previously been covered by the strategic alliance.
		•	We have no further obligation to provide research and development services to Mundipharma and Purdue as of July 17, 2012.
		•	Mundipharma and Purdue have no further obligation to provide research and development funding to us. Under the alliance, Mundipharma was obligated to reimburse us for research and development expenses we incurred, up to an annual aggregate cap for each alliance program other than FAAH. We recorded $0 and $47.1 million in collaborative research and development revenue for the three and nine months ended September 30, 2012, respectively. In addition, we recognized $46.6 million related to a gain on termination of Purdue entities alliance for the three and nine months ended September 30, 2012 as a result of the 2012 termination agreements. We did not record a liability for amounts previously funded by Purdue and Mundipharma as this relationship was not considered a financing arrangement.
		•	We are obligated to pay Mundipharma and Purdue a four percent royalty in the aggregate, subject to reduction as described below, on worldwide net sales of products that were covered by the alliance until such time as they have recovered approximately $260 million, representing the research and development funding paid to us for research and development services performed by us through the termination of the strategic alliance. After this cost recovery, our royalty obligations to Mundipharma and Purdue will be reduced to a one percent royalty on net sales in the United States of products that were previously subject to the strategic alliance. All payments are contingent upon the successful commercialization of products subject to the alliance, which products are subject to significant further development. As such, there is significant uncertainty about whether any such products will ever be approved or commercialized. If no products are commercialized, no payments will be due by us to Mundipharma and Purdue; therefore, no amounts have been accrued.
	Royalties are payable under these agreements until the later to occur of the last-to-expire of specified patent rights and the expiration of non-patent regulatory exclusivities in a country, provided that if royalties are payable solely on the basis of non-patent regulatory exclusivity, each of the royalty rates is reduced by 50 percent. In addition, royalties payable under these agreements after Mundipharma and Purdue have recovered all research and development expenses paid to us are subject to reduction on account of third party royalty payments or patent litigation damages or settlements which might be required to be paid by us if litigation were to arise, with any such reductions capped at 50 percent of the amounts otherwise payable during the applicable royalty payment period.
	Line of Credit Agreement
	In connection with the previous strategic alliance with Mundipharma and Purdue, we also entered into a line of credit agreement with Purdue and its independent associated company, Purdue Pharma L.P. (PPLP) that provided for the borrowing by us of one or more unsecured loans up to an aggregate maximum principal amount of $50 million. We recorded interest expense on the net amount borrowed using the effective interest method. We recorded $0.5 million and $1.9 million of related interest expense in the three and nine months ended September 30, 2012, respectively, using an effective interest rate of 7.29%.
	On September 7, 2012, upon completion of the sale and issuance of common stock to PPLP under the 2012 securities purchase agreement described below, the line of credit agreement with PPLP terminated in its entirety.
	2012 Securities Purchase Agreement; 2013 Offering
	On July 17, 2012, in connection with the termination of the strategic alliance with Mundipharma and Purdue, we executed a securities purchase agreement with PPLP, which we refer to as the 2012 securities purchase agreement, under which we agreed to sell and issue 5,416,565 shares of our common stock to PPLP and two entities associated with PPLP, which we collectively refer to as the BRP entities, at a price of $14.50 per share for an aggregate consideration of approximately $78.5 million. The consideration was composed of extinguishment of approximately $51.0 million in principal and interest owed to PPLP under a line of credit agreement and $27.5 million in cash. We completed the sale and issuance on September 7, 2012 at which time the line of credit agreement with PPLP terminated in its entirety.
	The 2012 securities purchase agreement also terminated, as of July 17, 2012, all attendance rights to meetings of our board of directors held by the Purdue entities.
	On April 16, 2013, the BRP entities, through two selling stockholders, sold 11,416,565 shares in an underwritten public offering at a price of $40 per share, representing their entire holdings in our common stock. In connection with the public offering and sale of their common stock, we entered into an agreement with the BRP entities, pursuant to which the 2012 securities purchase agreement, as amended in connection with the offering, terminated in its entirety. Following the closing of the offering, the BRP entities no longer owned any shares of our common stock at such time, and, as such, are no longer related parties.

Accrued_Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2013
Accrued Expenses	'
	8. Accrued Expenses
	Accrued expenses consisted of the following:
		September 30,		December 31,
		2013		2012
		(in thousands)
	Accrued compensation and benefits	$	5,463	$	5,555
	Accrued clinical studies		3,567		1,234
	Accrued drug manufacturing costs		957		1,288
	Other		1,926		1,982
	Total accrued expenses	$	11,913	$	10,059

Income_from_Massachusetts_Tax_

Income from Massachusetts Tax Incentive Award	9 Months Ended
	Sep. 30, 2013
Income from Massachusetts Tax Incentive Award	'
	9. Income from Massachusetts Tax Incentive Award
	During the nine months ended September 30, 2012, we recognized $0.2 million as other income due to the Massachusetts tax incentive award. We were awarded a tax grant from the Commonwealth of Massachusetts of approximately $0.5 million for the year ended December 31, 2009, which is earned over a five year period based on headcount growth. We achieved the headcount growth required by the award for the first two years and therefore recognized a pro rata portion of the grant. As the amount received for the award is not related to our ordinary course of operations, we have recorded the amount as other income. As we did not achieve the headcount growth as of December 31, 2012, we have repaid in 2013 the remaining $0.3 million to the Commonwealth of Massachusetts.

Restructuring_Activities

Restructuring Activities	9 Months Ended
	Sep. 30, 2013
Restructuring Activities	'
	10. Restructuring Activities
	In June 2012, we voluntarily stopped all company-sponsored clinical trials of saridegib, our Hedgehog pathway inhibitor. We reallocated remaining resources to other potential development programs and product portfolio efforts and reduced our work force. In July 2012, we agreed with Mundipharma and Purdue to terminate our strategic alliance agreements with the result that Mundipharma would have no further obligation to provide research and development funding to us (see note 7), and therefore we undertook a subsequent workforce reduction.
	The associated restructuring expenses were recorded as research and development and general and administrative expenses. We recorded a restructuring expense of $1.2 million and $2.6 million during the three and nine months ended September 30, 2012, respectively. The remaining balance payable as of December 31, 2012 was $0.4 million related to employee severance, benefits and related costs. All amounts have been paid as of September 30, 2013.

Significant_Accounting_Policie1

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2013
Cash Equivalents and Available-For-Sale Securities	'
	Cash Equivalents and Available-For-Sale Securities
	Cash equivalents and available-for-sale securities primarily consist of money market funds, U.S. government-sponsored enterprise obligations, corporate obligations, U.S. treasury securities and mortgage-backed securities. Corporate obligations include obligations issued by corporations in countries other than the United States, including some obligations that have not been guaranteed by governments and government agencies. We consider all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents. Cash equivalents, which consist of money market funds and corporate obligations, are stated at fair value. They are also readily convertible to known amounts of cash and have such short-term maturities that each presents insignificant risk of change in value due to changes in interest rates. Our classification of cash equivalents is consistent with prior periods.
	We determine the appropriate classification of marketable securities at the time of purchase and reevaluate such designation at each balance sheet date. We have classified all of our marketable securities at September 30, 2013 and December 31, 2012 as “available-for-sale.” We carry available-for-sale securities at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income (loss), which is a separate component of stockholders’ equity.
	We adjust the cost of available-for-sale debt securities for amortization of premiums and accretion of discounts to maturity. We include such amortization and accretion in interest and investment income. The cost of securities sold is based on the specific identification method. We include in investment income interest and dividends on securities classified as available-for-sale.
	We conduct periodic reviews to identify and evaluate each investment that is in an unrealized loss position in order to determine whether an other-than-temporary impairment exists. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. Unrealized losses on available-for-sale debt securities that are determined to be temporary, and not related to credit loss, are recorded, net of tax, in accumulated other comprehensive income (loss).
	For available-for-sale debt securities in an unrealized loss position, we perform an analysis to assess whether we intend to sell or whether we would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. Where we intend to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary, and the full amount of the unrealized loss is recorded within earnings as an impairment loss.
	Regardless of our intent to sell a security, we perform additional analysis on all securities in an unrealized loss position to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where we do not expect to receive cash flows sufficient to recover the amortized cost basis of a security and are recorded within earnings as an impairment loss.
Segment Information	'
	Segment Information
	We operate in one business segment, which focuses on drug discovery and development. We make operating decisions based upon performance of the enterprise as a whole and utilize our consolidated financial statements for decision making.
	All of our revenues to date have been generated under research collaboration agreements. Revenue associated with the amortization of the deferred revenue associated with the grant of rights and licenses to, and reimbursed research and development services provided to, Mundipharma International Corporation Limited (Mundipharma), and Purdue Pharmaceutical Products L.P. (Purdue), accounted for all of our revenue for the nine months ended September 30, 2012. We considered Mundipharma, Purdue and their respective associated entities to be related parties for financial reporting purposes because of their equity ownership prior to April 2013 (see note 7).
Basic and Diluted Loss per Common Share	'
	Basic and Diluted Loss per Common Share
	Basic net loss per share is based upon the weighted average number of common shares outstanding during the period. Diluted net loss per share is based upon the weighted average number of common shares outstanding during the period plus the effect of additional weighted average common equivalent shares outstanding during the period when the effect of adding such shares is dilutive. Common equivalent shares result from the assumed exercise of outstanding stock options (the proceeds of which are then assumed to have been used to repurchase outstanding stock using the treasury stock method). In addition, the assumed proceeds under the treasury stock method include the average unrecognized compensation expense of stock options that are in-the-money. This results in the “assumed” buyback of additional shares, thereby reducing the dilutive impact of stock options. Common equivalent shares have not been included in the net loss per share calculations for the periods presented because the effect of including them would have been anti-dilutive. Total potential gross common equivalent shares consisted of the following:
			At September 30,
			2013			2012
	Stock options			6,255,772			7,113,072
	Warrants			—			136,655
	Basic and diluted earnings (loss) per common share were determined as follows:
			Three Months Ended					Nine Months Ended
			September 30,					September 30,
			2013			2012		2013			2012
			(in thousands, except share and per share amounts)
	Basic
	Net income (loss)		$	(33,938	)	$	18,403	$	(93,855	)	$	(6,979	)
	Weighted average common shares outstanding			48,052,939			32,039,866		47,875,706			28,638,512
	Basic earnings (loss) per common share		$	(0.71	)	$	0.57	$	(1.96	)	$	(0.24	)
	Diluted
	Net income (loss)		$	(33,938	)	$	18,403	$	(93,855	)	$	(6,979	)
	Weighted average common shares outstanding			48,052,939			32,039,866		47,875,706			28,638,512
	Effect of dilutive options			—			3,133,357		—			—
	Weighted average common shares outstanding assuming dilution			48,052,939			35,173,223		47,875,706			28,638,512
	Diluted earnings (loss) per common share		$	(0.71	)	$	0.52	$	(1.96	)	$	(0.24	)
Comprehensive Loss	'
	Comprehensive Loss
	Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) is comprised of unrealized holding gains and losses arising during the period on available-for-sale securities that are not other-than-temporarily impaired. During the nine months ended September 30, 2013, there were no reclassifications out of accumulated other comprehensive income (loss).
Stock-Based Compensation Expense	'
	Stock-Based Compensation Expense
	For awards granted to employees and directors, including our Employee Stock Purchase Plan (“ESPP”), we measure stock-based compensation cost at the grant date based on the estimated fair value of the award and recognize it as expense over the requisite service period on a straight-line basis. The ESPP permits eligible employees to purchase shares of our common stock at a discount and consists of consecutive, overlapping 24-month offering periods, each consisting of four six-month purchase periods. On the first day of each offering period, each employee who is enrolled in the ESPP will automatically receive an option to purchase up to a whole number of shares of our common stock. The purchase price of each of the shares purchased in a given purchase period will be 85% of the closing price of a share of our common stock on the first day of the offering period or the last day of the purchase period, whichever is lower. We record the expense of services rendered by non-employees based on the estimated fair value of the stock option as of the respective vesting date. We use the Black-Scholes valuation model in determining the fair value of all equity awards. We have no awards with market or performance conditions.
Revenue Recognition	'
	Revenue Recognition
	To date, all of our revenue has been generated under research collaboration agreements. The terms of these research collaboration agreements may include payment to us of non-refundable, up-front license fees, funding or reimbursement of research and development efforts, milestone payments if specified objectives are achieved, and/or royalties on product sales. We recognize revenue based upon our best estimate of the selling price for an undelivered item when there is no other means to determine the fair value of that undelivered item.
	Under our previous strategic alliance with Mundipharma and Purdue, we recognized revenues from non-refundable, up-front license fees on a straight-line basis over the contracted or estimated period of performance, which was the research and development term. We regularly considered whether events warranted a change in the estimated period of performance under an agreement. Such a change would have caused us to modify the period of time over which we recognized revenue from the up-front license fee on a prospective basis and would have, in turn, resulted in changes in our quarterly and annual results. We recognized research and development funding as earned over the period of effort as related research and development costs were incurred in proportion to our forecasted total expenses as compared to the total expected research and development funding for the year. We recognized the impact of any change in forecasted total expenses or expected research and development funding as a change in accounting estimate and recorded the impact of that change on a prospective basis. On July 17, 2012, we mutually agreed with Mundipharma and Purdue to terminate our strategic alliance agreements. Further information regarding the terms and conditions of this termination is described below under note 7.
	At the inception of each agreement that includes milestone payments, we evaluate whether each milestone is substantive on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether:
		•		the consideration is commensurate with either (1) our performance to achieve the milestone, or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from our performance to achieve the milestone,
		•		the consideration relates solely to past performance, and
		•		the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement.
	We evaluate factors such as the clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment. We recognize revenues related to substantive milestones in full in the period in which the substantive milestone is achieved. If a milestone payment is not considered substantive, we recognize the applicable milestone over the remaining period of performance. Our strategic alliance with Mundipharma and Purdue did not include potential milestone payments.
	We will recognize royalty revenue, if any, based upon actual and estimated net sales by the licensee of licensed products in licensed territories in the period the sales occur. We have not recognized any royalty revenue to date.
Research and Development Expense	'
	Research and Development Expense
	Research and development expense consists of expenses incurred in performing research and development activities, including salaries and benefits, overhead expenses including facilities expenses, materials and supplies, preclinical expenses, clinical trial and related clinical manufacturing expenses, stock-based compensation expense, depreciation of equipment, contract services, and other outside expenses. We also include as research and development expense up-front license payments related to acquired technologies which have not yet reached technological feasibility and have no alternative use. We expense research and development costs as they are incurred. We capitalize nonrefundable advance payments related to research and development activities and expense the payments as the related goods are delivered or the related services are performed. We have been a party to collaboration agreements in which we were reimbursed for work performed on behalf of the collaborator, as well as one in which we reimbursed the collaborator for work it had performed. We record all appropriate expenses under our collaborations as research and development expense. If the arrangement provides for reimbursement of research and development expenses, as was the case with our alliance with Mundipharma and Purdue, we record the reimbursement as revenue. If the arrangement provides for us to reimburse the collaborator for research and development expenses or achieving a development milestone for which a payment is due, as was the case with our agreement with Intellikine, Inc. (Intellikine), we record the reimbursement or the achievement of the development milestone as research and development expense. In January 2012, Intellikine was acquired by Takeda Pharmaceutical Company Limited (Takeda) acting through its Millennium business unit.
Income Taxes	'
	Income Taxes
	We use the liability method to account for income taxes. Deferred tax assets and liabilities are determined based on differences between financial reporting and income tax basis of assets and liabilities, as well as net operating loss and tax credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when the differences reverse. Deferred tax assets are reduced by a valuation allowance to reflect the uncertainty associated with their ultimate realization. The effect of a change in tax rate on deferred taxes is recognized in income or loss in the period that includes the enactment date.
	We use our judgment for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We recognize any material interest and penalties related to unrecognized tax benefits in income tax expense.
	Due to the uncertainty surrounding the realization of the net deferred tax assets in future periods, we have recorded a full valuation allowance against our otherwise recognizable net deferred tax assets as of September 30, 2013 and December 31, 2012.
Fair Value Measurements	'
	Fair Value Measurements
	We define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We determine fair value based on the assumptions market participants use when pricing the asset or liability. We also use the fair value hierarchy that prioritizes the information used to develop these assumptions.
	We value our available-for-sale securities utilizing third party pricing services. The pricing services use many observable market inputs to determine value, including benchmark yields, reportable trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, new issue data, monthly payment information and collateral performance. We validate the prices provided by our third party pricing services by understanding the models used, obtaining market values from other pricing sources, and confirming that those securities trade in active markets.
	We value the balance of the release payment due to Millennium based on a discounted cash flow model.
Property and Equipment	'
	Property and Equipment
	Property and equipment are stated at cost. Depreciation is recorded using the straight-line method over the estimated useful lives of the applicable assets. Application development costs incurred for computer software developed or obtained for internal use are capitalized. Upon sale or retirement, the cost and related accumulated depreciation are eliminated from the respective account, and the resulting gain or loss, if any, is included in current operations. Amortization of leasehold improvements and capital leases are included in depreciation expense. Repairs and maintenance charges that do not increase the useful life of the assets are charged to operations as incurred. Property and equipment are depreciated over the following periods:
	Laboratory equipment		5 years
	Computer equipment and software		3 to 5 years
	Leasehold improvements		Shorter of lease term or useful life of asset
	Furniture and fixtures		7 years

Significant_Accounting_Policie2

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2013
Total Potential Gross Common Equivalent Shares	'
	Total potential gross common equivalent shares consisted of the following:
		At September 30,
		2013			2012
	Stock options		6,255,772			7,113,072
	Warrants		—			136,655
Basic and Diluted Earnings (Loss) per Common Share	'
	Basic and diluted earnings (loss) per common share were determined as follows:
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2013			2012		2013			2012
		(in thousands, except share and per share amounts)
	Basic
	Net income (loss)	$	(33,938	)	$	18,403	$	(93,855	)	$	(6,979	)
	Weighted average common shares outstanding		48,052,939			32,039,866		47,875,706			28,638,512
	Basic earnings (loss) per common share	$	(0.71	)	$	0.57	$	(1.96	)	$	(0.24	)
	Diluted
	Net income (loss)	$	(33,938	)	$	18,403	$	(93,855	)	$	(6,979	)
	Weighted average common shares outstanding		48,052,939			32,039,866		47,875,706			28,638,512
	Effect of dilutive options		—			3,133,357		—			—
	Weighted average common shares outstanding assuming dilution		48,052,939			35,173,223		47,875,706			28,638,512
	Diluted earnings (loss) per common share	$	(0.71	)	$	0.52	$	(1.96	)	$	(0.24	)
Property and Equipment, Depreciation Periods	'
	Property and equipment are depreciated over the following periods:
	Laboratory equipment	5 years
	Computer equipment and software	3 to 5 years
	Leasehold improvements	Shorter of lease term or useful life of asset
	Furniture and fixtures	7 years

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2013
Stock-Based Compensation Expense, Related to All Equity Awards	'
	Total stock-based compensation expense, related to all equity awards, for the three and nine months ended September 30, 2013 and 2012 comprised the following:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
		(in thousands)
	Effect of stock-based compensation on net loss by line item:
	Research and development	$	1,599		$	772		$	4,618		$	2,371
	General and administrative		1,660			995			4,717			2,711
Black-Scholes Valuation Model, Weighted-Average Assumptions	'
	For the three and nine months ended September 30, 2013 and 2012, the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Risk-free interest rate		1.3	%		0.8	%		0.9	%		1.1	%
	Expected annual dividend yield		—			—			—			—
	Expected stock price volatility		71.3	%		62.6	%		63.2	%		63.3	%
	Expected term of options		4.7 years			6.2 years			4.9 years			6.1 years

Cash_Cash_Equivalents_and_Avai1

Cash, Cash Equivalents and Available-for-Sale Securities (Tables)	9 Months Ended
	Sep. 30, 2013
Summary of Cash, Cash Equivalents and Available-for-sale Securities	'
	The following is a summary of cash, cash equivalents and available-for-sale securities:
		September 30, 2013
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	53,478	$	—	$	—		$	53,478
	Available-for-sale securities:
	Corporate obligations due in one year or less		116,871		51		(20	)		116,902
	Corporate obligations due in one to five years		18,574		37		—			18,611
	Mortgage-backed securities due after ten years		489		65		—			554
	U.S. government-sponsored enterprise obligations due in one year or less		22,004		8		—			22,012
	U.S. government-sponsored enterprise obligations due in one to five years		39,277		23		—			39,300
	Total available-for-sale securities		197,215		184		(20	)		197,379
	Total cash, cash equivalents and available-for- sale securities	$	250,693	$	184	$	(20	)	$	250,857
		December 31, 2012
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	175,742	$	—	$	—		$	175,742
	Available-for-sale securities:
	Corporate obligations due in one year or less		88,644		53		(13	)		88,684
	Corporate obligations due in one to five years		16,291		8		(9	)		16,290
	Mortgage-backed securities due after ten years		547		70		—			617
	U.S. government-sponsored enterprise obligations due in one year or less		38,779		22		—			38,801
	U.S. government-sponsored enterprise obligations due in one to five years		6,498		3		—			6,501
	Total available-for-sale securities		150,759		156		(22	)		150,893
	Total cash, cash equivalents and available-for-sale securities	$	326,501	$	156	$	(22	)	$	326,635

Fair_Value_Tables

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2013
Assets Carried at Fair Value Measured on Recurring Basis	'
	The following table provides the assets carried at fair value measured on a recurring basis as of September 30, 2013:
		Level 1		Level 2
		(in thousands)
	Cash and cash equivalents	$	44,876	$	8,602
	Corporate obligations (including commercial paper)		—		135,513
	Mortgage-backed securities		—		554
	U.S. government-sponsored enterprise obligations		—		61,312
	Total	$	44,876	$	205,981

Accrued_Expenses_Tables

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2013
Accrued Expenses	'
	Accrued expenses consisted of the following:
		September 30,		December 31,
		2013		2012
		(in thousands)
	Accrued compensation and benefits	$	5,463	$	5,555
	Accrued clinical studies		3,567		1,234
	Accrued drug manufacturing costs		957		1,288
	Other		1,926		1,982
	Total accrued expenses	$	11,913	$	10,059

Significant_Accounting_Policie3

Significant Accounting Policies - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013
	Segment
Significant Accounting Policies [Line Items]	'
Number of operating segments	1
Reclassifications out of accumulated other comprehensive income loss	'
ESPP	'
Significant Accounting Policies [Line Items]	'
Common stock offering aggregate period	'24 months
Number of common stock purchase period	4
Common stock offering purchase period	'6 months
percentage of common stock purchase price	85.00%
Maximum	'
Significant Accounting Policies [Line Items]	'
Maturity of highly liquid investments	'3 months

Total_Potential_Gross_Common_E

Total Potential Gross Common Equivalent Shares (Detail)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Stock Options	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Common equivalent shares excluded from computation of earnings per share, amount	6,255,772	7,113,072
Warrants	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Common equivalent shares excluded from computation of earnings per share, amount	'	136,655

Basic_and_Diluted_Earnings_Los

Basic and Diluted Earnings (Loss) per Common Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Basic	'	'	'	'
Net income (loss)	($33,938)	$18,403	($93,855)	($6,979)
Weighted average common shares outstanding	48,052,939	32,039,866	47,875,706	28,638,512
Basic earnings (loss) per common share	($0.71)	$0.57	($1.96)	($0.24)
Diluted	'	'	'	'
Net income (loss)	($33,938)	$18,403	($93,855)	($6,979)
Weighted average common shares outstanding	48,052,939	32,039,866	47,875,706	28,638,512
Effect of dilutive options	'	3,133,357	'	'
Weighted average common shares outstanding assuming dilution	48,052,939	35,173,223	47,875,706	28,638,512
Diluted earnings (loss) per common share	($0.71)	$0.52	($1.96)	($0.24)

Property_and_Equipment_Depreci

Property and Equipment, Depreciation Periods (Detail)	9 Months Ended
	Sep. 30, 2013
Laboratory Equipment	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'5 years
Computer Equipment and Software | Minimum	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'3 years
Computer Equipment and Software | Maximum	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'5 years
Leasehold Improvements	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'Shorter of lease term or useful life of asset
Furniture and Fixtures	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'7 years

Stock_Based_Compensation_Expen

Stock Based Compensation Expense, Related to All Equity Awards (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
Research and Development	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Effect of stock-based compensation on net loss	$1,599	$772	$4,618	$2,371
General and Administrative	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Effect of stock-based compensation on net loss	$1,660	$995	$4,717	$2,711

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Unrecognized compensation cost, net of estimated forfeitures, related to unvested stock options and awards under ESPP	$22.80	'
Unrecognized compensation cost, weighted-average recognition period	'2 years 10 months 24 days	'
Stock options exercised	534,284	'
Stock options exercised, weighted average exercise price	$8.51	'
Stock options granted	1,371,094	1,697,913
Stock options granted, weighted average fair value	$18.35	$5.97
Stock options granted, weighted average exercise price	$33.09	$10.34

BlackScholes_Valuation_Model_W

Black-Scholes Valuation Model, Weighted-Average Assumptions (Detail)	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]	'	'	'	'
Risk-free interest rate	1.30%	0.80%	0.90%	1.10%
Expected annual dividend yield	'	'	'	'
Expected stock price volatility	71.30%	62.60%	63.20%	63.30%
Expected term of options	'4 years 8 months 12 days	'6 years 2 months 12 days	'4 years 10 months 24 days	'6 years 1 month 6 days

Summary_of_Cash_Cash_Equivalen

Summary of Cash, Cash Equivalents and Available-for-sale Securities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Cash and cash equivalents due in 90 days or less, Cost	$53,478	$175,742	'	'
Cash and cash equivalents due in 90 days or less, Gross Unrealized Gains	'	'	'	'
Cash and cash equivalents due in 90 days or less, Gross Unrealized Losses	'	'	'	'
Cash and cash equivalents due in 90 days or less, Estimated Fair Value	53,478	175,742	52,917	24,197
Total available-for-sale securities, Cost	197,215	150,759	'	'
Total available-for-sale securities, Gross Unrealized Gains	184	156	'	'
Total available-for-sale securities, Gross Unrealized Losses	-20	-22	'	'
Total available-for-sale securities, Estimated Fair Value	197,379	150,893	'	'
Total cash, cash equivalents and available-for-sale securities, Cost	250,693	326,501	'	'
Total cash, cash equivalents and available-for-sale securities, Gross Unrealized Gains	184	156	'	'
Total cash, cash equivalents and available-for-sale securities, Gross Unrealized Losses	-20	-22	'	'
Total cash, cash equivalents and available-for-sale securities	250,857	326,635	'	'
Corporate Obligations	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available-for-sale securities, due in one year or less, Cost	116,871	88,644	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Gains	51	53	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Losses	-20	-13	'	'
Available-for-sale securities, due in one year or less, Estimated Fair Value	116,902	88,684	'	'
Available-for-sale securities, due in one to five years, Cost	18,574	16,291	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Gains	37	8	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Losses	'	-9	'	'
Available-for-sale securities, due in one to five years, Estimated Fair Value	18,611	16,290	'	'
Mortgage-Backed Securities	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available-for-sale securities due after ten years, Cost	489	547	'	'
Available-for-sale securities due after ten years, Gross Unrealized Gains	65	70	'	'
Available-for-sale securities due after ten years, Estimated Fair Value	554	617	'	'
U.S. Government Sponsored Enterprise Obligations	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available-for-sale securities, due in one year or less, Cost	22,004	38,779	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Gains	8	22	'	'
Available-for-sale securities, due in one year or less, Estimated Fair Value	22,012	38,801	'	'
Available-for-sale securities, due in one to five years, Cost	39,277	6,498	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Gains	23	3	'	'
Available-for-sale securities, due in one to five years, Estimated Fair Value	$39,300	$6,501	'	'

Cash_Cash_Equivalents_and_Avai2

Cash, Cash Equivalents and Available-for-Sale Securities - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available-for-sale securities realized gains or losses	$0	$0	$0	$0
Other-than-temporary impairments on Available-for-sale securities	0	0	0	0
Less Than Twelve Months	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Number of debt securities held in an unrealized loss position	11	'	11	'
Available for sale securities debt fair value	38,700,000	'	38,700,000	'
Foreign Financial Institution and Other Corporate Debt Securities	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available for sale securities number of financial institution and other corporate debt securities located in foreign countries	21	'	21	'
Available for sale securities debt fair value	87,500,000	'	87,500,000	'
Number of securities unrealized losses	5	'	5	'
Available for sale securities debt gross unrealized losses	'	'	14,000	'
Available for sale securities debt fair value, short term	$17,600,000	'	$17,600,000	'

Assets_Carried_at_Fair_Value_M

Assets Carried at Fair Value Measured on Recurring Basis (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash, cash equivalents and available-for-sale securities	$250,857	$326,635
Level 1	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	44,876	'
Total cash, cash equivalents and available-for-sale securities	44,876	'
Level 2	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	8,602	'
Corporate obligations (including commercial paper)	135,513	'
Mortgage-backed securities	554	'
U.S. government-sponsored enterprise obligations	61,312	'
Total cash, cash equivalents and available-for-sale securities	$205,981	'

Fair_Value_Additional_Informat

Fair Value - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available-for-sale securities	$197,379,000	$150,893,000
Transfers of assets or liabilities between Level 1 and Level 2	0	'
Payment at Fair value	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Due to Millennium, Fair value	13,100,000	'
Fair Value, Inputs, Level 3	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available-for-sale securities	$0	$0
Maximum	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents maturity period	'3 months	'

Collaborations_Additional_Info

Collaborations - Additional Information (Detail) (USD $)

1 Months Ended

3 Months Ended

9 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

9 Months Ended

Jul. 17, 2012

Jul. 31, 2010

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Nov. 30, 2008

Apr. 30, 2013

Jul. 17, 2012

Jul. 17, 2012

Dec. 31, 2012

Jul. 17, 2012

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2013

Entity

BRP

Line of Credit

Cash

Amended Agreement

Mundipharma and Purdue

Maximum

Minimum

Minimum

Installment

Forecast

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Up-front license fee

'

$13,500,000

'

'

'

'

'

'

'

'

'

'

'

'

Share of profits and losses on development and commercialization

'

'

'

'

'

'

'

'

'

50.00%

'

'

'

'

Percentage of detailing effort for products

'

'

'

'

'

'

'

'

'

30.00%

'

'

'

'

Release payment

'

'

'

'

'

'

'

'

'

15,000,000

'

'

'

'

Release payment, fair value

'

'

'

'

'

'

'

'

'

14,400,000

'

'

'

'

Amount paid on release payment during the period

'

'

'

'

'

'

'

'

'

1,700,000

'

'

'

'

Number of installments on release payment

'

'

'

'

'

'

'

'

'

2

'

'

'

'

Development cost of distinct product candidates

'

'

'

'

'

'

'

'

'

'

'

15,000,000

'

10,000,000

Number of distinct product candidates

'

'

'

2

'

'

'

'

'

'

'

'

'

'

Approval and commercialization cost of distinct products payable

'

'

'

'

'

'

'

'

'

'

'

450,000,000

'

'

Percent of royalty on net sale

'

'

'

'

'

'

'

'

'

'

'

11.00%

7.00%

'

Prior written notice for termination on the breach of agreement by the other party

'

'

'

'75 days

'

'

'

'

'

'

'

'

'

'

Prior written notice for termination on nonpayment by the other party

'

'

'

'30 days

'

'

'

'

'

'

'

'

'

'

Prior written notice for termination after the end of the research term

'

'

'

'180 days

'

'

'

'

'

'

'

'

'

'

Strategic Alliance Agreement Termination date

'

'

'

'

'

'

'

'

'

'

'July 17, 2012

'

'

'

Revenue for reimbursed research and development services

'

'

0

'

47,100,000

'

'

'

'

'

'

'

'

'

Gain on termination of Purdue entities alliance

'

'

46,555,000

'

46,555,000

'

'

'

'

'

'

'

'

'

Royalty rate on future sales

4.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Recovery of research and development funding

260,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Royalty rate payable after initial research and development cost recovery

'

'

'

'

'

'

'

'

'

'

1.00%

'

'

'

Royalty payable description

'After this cost recovery, our royalty obligations to Mundipharma and Purdue will be reduced to a one percent royalty on net sales in the United States of products that were previously subject to the strategic alliance.

'

'

'

'

'

'

'

'

'

'

'

'

'

Royalty term and royalty rate reduction

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Royalty payment, maximum reduction

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Line Of credit facility maximum borrowing capacity

'

'

'

'

'

50,000,000

'

'

'

'

'

'

'

'

Interest expense

'

'

500,000

'

1,900,000

'

'

'

'

'

'

'

'

'

Effective interest expense

'

'

7.29%

'

7.29%

'

'

'

'

'

'

'

'

'

Stock to be issued under securities purchase agreement

5,416,565

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate consideration to be received on stock transaction

78,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt amount plus accrued interest

'

'

'

'

'

'

'

51,000,000

'

'

'

'

'

'

Sale of stock consideration to be received on transaction

'

'

'

'

'

'

'

'

$27,500,000

'

'

'

'

'

Stock to be issued under securities purchase agreement, price per share

$14.50

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of entities

2

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of shares of common stock sold

'

'

'

'

'

'

11,416,565

'

'

'

'

'

'

'

Number of shares of common stock sold, per share

'

'

'

'

'

'

$40

'

'

'

'

'

'

'

Accrued_Expenses_Detail

Accrued Expenses (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Accrued Expenses [Line Items]	'	'
Accrued compensation and benefits	$5,463	$5,555
Accrued clinical studies	3,567	1,234
Accrued drug manufacturing costs	957	1,288
Other	1,926	1,982
Total accrued expenses	$11,913	$10,059

Income_from_Massachusetts_Tax_1

Income from Massachusetts Tax Incentive Award - Additional Information (Detail) (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2009
			Y
Other Income Net [Line Items]	'	'	'
Income from Massachusetts tax incentive award	'	$193,000	'
Tax grant award from Commonwealth of Massachusetts	'	'	500,000
Tax grant period	'	'	5
Tax grant repaid	$300,000	'	'

Restructuring_Activities_Addit

Restructuring Activities - Additional Information (Detail) (Employee Severance, USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2012	Dec. 31, 2012
Employee Severance	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'
Restructuring charges	$1.20	$2.60	'
Restructuring charges payable	'	'	$0.40