Infinity Pharmaceuticals (INFIQ) 10-Q 10 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Nov. 03, 2014
Document Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
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	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	48,766,883

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$321,257	$68,114
Available-for-sale securities	57,745	145,772
Loan commitment asset, net (note 8)	1,681	'
Prepaid expenses and other current assets	10,032	11,055
Total current assets	390,715	224,941
Property and equipment, net	2,982	4,010
Long-term available-for-sale securities	533	582
Restricted cash	2,162	1,130
Other assets	433	47
Total assets	396,825	230,710
Current liabilities:	'	'
Accounts payable	11,041	6,375
Accrued expenses	18,764	9,164
Due to Takeda, current	6,614	6,667
Deferred revenue, current	21,994	'
Total current liabilities	58,413	22,206
Due to Takeda, less current portion	'	6,456
Deferred revenue, less current portion	92,367	'
Other liabilities	529	773
Total liabilities	151,309	29,435
Commitments and contingencies	'	'
Stockholders' equity:	'	'
Preferred Stock, $0.001 par value; 1,000,000 shares authorized, no shares issued and outstanding at September 30, 2014 and December 31, 2013	'	'
Common Stock, $0.001 par value; 100,000,000 shares authorized, and 48,725,249 and 48,227,838 shares issued and outstanding, at September 30, 2014 and December 31, 2013, respectively	49	48
Additional paid-in capital	672,206	650,867
Accumulated deficit	-426,870	-449,796
Accumulated other comprehensive income	131	156
Total stockholders' equity	245,516	201,275
Total liabilities and stockholders' equity	$396,825	$230,710

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
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	48,725,249	48,227,838
Common Stock, shares outstanding	48,725,249	48,227,838

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, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Collaboration revenue	$160,639	'	$160,639	'
Operating expenses:	'	'	'	'
Research and development	44,895	26,857	107,551	73,168
General and administrative	8,042	7,319	21,903	21,424
Total operating expenses	52,937	34,176	129,454	94,592
Income (loss) from operations	107,702	-34,176	31,185	-94,592
Other income (expense):	'	'	'	'
Interest expense	-4,537	'	-8,615	'
Investment and other income	52	238	356	737
Total other income (expense)	-4,485	238	-8,259	737
Net income (loss)	103,217	-33,938	22,926	-93,855
Earnings (loss) per common share:	'	'	'	'
Basic	$2.08	($0.71)	$0.47	($1.96)
Diluted	$2.03	($0.71)	$0.46	($1.96)
Weighted average number of common shares outstanding:	'	'	'	'
Basic	48,632,888	48,052,939	48,497,305	47,875,706
Diluted	49,735,303	48,052,939	49,533,122	47,875,706
Other comprehensive loss:	'	'	'	'
Net unrealized holding gains (losses) on available-for-sale securities arising during the period	-31	117	-25	30
Comprehensive income (loss)	$103,186	($33,821)	$22,901	($93,825)

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating activities	'	'
Net income (loss)	$22,926	($93,855)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation	1,367	1,336
Stock-based compensation, including 401(k) match	9,623	9,335
Net amortization of premium/discount on available-for-sale securities	1,128	1,570
Non-cash interest expense on amount Due to Takeda	158	310
Amortization of loan commitment asset	8,615	'
Other, net	25	-2
Changes in operating assets and liabilities:	'	'
Prepaid expenses and other assets	637	-919
Accounts payable, accrued expenses and other liabilities	12,522	4,787
Due to Takeda	-6,667	'
Deferred revenue	114,361	'
Net cash provided by (used in) operating activities	164,695	-77,438
Investing activities	'	'
Purchases of property and equipment	-364	-1,346
Purchases of available-for-sale securities	-21,789	-230,599
Proceeds from sales of available-for-sale securities	'	1,031
Proceeds from maturities of available-for-sale securities	108,711	181,543
Net cash provided by (used in) investing activities	86,558	-49,371
Financing activities	'	'
Proceeds from issuances of common stock related to stock incentive plans	2,973	4,545
Proceeds from issuances of common stock related to employee stock purchase plan	393	'
Restricted cash	-1,030	'
Deferred transaction costs	-446	'
Net cash provided by financing activities	1,890	4,545
Net increase (decrease) in cash and cash equivalents	253,143	-122,264
Cash and cash equivalents at beginning of period	68,114	175,742
Cash and cash equivalents at end of period	321,257	53,478
Supplemental schedule of noncash investing and financing activities	'	'
Loan commitment asset	9,850	'
Facility fee	1,500	'
Warrants issued	$8,350	'

Organization

Organization	9 Months Ended
	Sep. 30, 2014
Organization	'
	1. Organization
	Infinity Pharmaceuticals, Inc. is an innovative biopharmaceutical company dedicated to discovering, developing and delivering best-in-class medicines to patients with 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 subsidiaries.

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2014
Basis of Presentation	'
	2. Basis of Presentation
	These condensed consolidated financial statements include the accounts of Infinity and its wholly owned subsidiaries. We have eliminated all significant intercompany accounts and transactions in consolidation.
	The accompanying 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 accompanying condensed consolidated financial statements have been included. Interim results for the three and nine months ended September 30, 2014 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2014.
	The information presented in the condensed consolidated financial statements and related footnotes at September 30, 2014, and for the three and nine months ended September 30, 2014 and 2013, is unaudited, and the condensed consolidated balance sheet amounts and related footnotes at December 31, 2013 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, 2013, which was filed with the U.S. Securities and Exchange Commission on February 25, 2014.

Significant_Accounting_Policie

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2014
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 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 or 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, 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, 2014 and December 31, 2013 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, 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 investment and other income. The cost of securities sold is based on the specific identification method. We include in investment and other 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 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.
	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 decline in fair value of the security 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.
	Basic and Diluted Net 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 and the exercise of outstanding warrants (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. The two-class method is used for outstanding warrants as it is considered to be a participating security and it is more dilutive than the treasury stock method. The following outstanding shares of common stock equivalents were excluded from the computation of net income (loss) per share attributable to common stockholders for the periods presented because including them would have been antidilutive:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
			2014			2013			2014			2013
	Stock Options			3,711,997			6,255,772			3,715,825			6,255,772
	Warrants (excluded from treasury stock method)			1,000,000			—			1,000,000			—
	Basic and diluted earnings (loss) per common share were determined as follows:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
			2014			2013			2014			2013
			(in thousands, except share and per share amounts)
	Basic
	Net income (loss)		$	103,217		$	(33,938	)	$	22,926		$	(93,855	)
	Undistributed earnings allocated to warrants			(2,080	)		—			(362	)		—
	Net income (loss)		$	101,137		$	(33,938	)	$	22,564		$	(93,855	)
	Weighted average common shares outstanding			48,632,888			48,052,939			48,497,305			47,875,706
	Basic earnings (loss) per common share		$	2.08		$	(0.71	)	$	0.47		$	(1.96	)
	Diluted
	Net income (loss)		$	103,217		$	(33,938	)	$	22,926		$	(93,855	)
	Undistributed earnings allocated to warrants			(2,034	)		—			(354	)		—
	Net income (loss)		$	101,183		$	(33,938	)	$	22,572		$	(93,855	)
	Weighted average common shares outstanding			48,632,888			48,052,939			48,497,305			47,875,706
	Effect of dilutive options			1,102,415			—			1,035,817			—
	Weighted average common shares outstanding assuming dilution			49,735,303			48,052,939			49,533,122			47,875,706
	Diluted earnings (loss) per common share		$	2.03		$	(0.71	)	$	0.46		$	(1.96	)
	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, 2014, 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, or 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. 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. For awards with performance conditions, we estimate the likelihood of satisfaction of the performance conditions, which affects the period over which the expense is recognized, and recognize the expense over the requisite service period on a straight-line basis. We have no awards with market 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, upfront license fees, funding or reimbursement of research and development efforts, milestone payments if specified objectives are achieved, and/or royalties on product sales. We evaluate all deliverables within an arrangement to determine whether or not they provide value on a stand-alone basis. Based on this evaluation, the deliverables are separated into units of accounting. For each unit of accounting identified within an arrangement, we determine the period over which the performance obligation occurs. Revenue is then recognized using the proportional performance method. The proportional performance method is used when the level of effort to complete the performance obligations under an arrangement can be reasonably estimated. 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. The process for determining the best estimate of the selling price involves significant judgment and estimates.
	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.
	In making this assessment, 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. 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.
	We will recognize royalty revenue, if any, based upon actual and estimated net sales by the licensee of licensed products in licensed territories, and 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, comparator drug expenses, stock-based compensation expense, depreciation of equipment, contract services, and other outside expenses. We also include as research and development expense upfront 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. Prepaid comparator drug expenses are capitalized and then recognized as expense when title transfers to us. 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 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., or 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, or Takeda, acting through its Millennium business unit. We refer to our phosphoinositide-3-kinase, or P13K, program licensor as Takeda.
	Income Taxes
	We use the liability method to account for income taxes. Deferred tax assets and liabilities are determined based on temporary 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, 2014 and December 31, 2013.
	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 Takeda 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 is recorded as depreciation expense and included in research and development and general and administrative 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, 2014
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, 2014 and 2013 comprised the following:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
		(in thousands)
	Effect of stock-based compensation on net loss by line item:
	Research and development	$	1,760		$	1,599		$	5,736		$	4,618
	General and administrative		1,172			1,660			3,887			4,717
	As of September 30, 2014, we had approximately $19.8 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 2.4 years.
	Stock Options
	During the nine months ended September 30, 2014, we granted options to purchase 1,532,384 shares of our common stock at a weighted-average fair value of $7.43 and a weighted-average exercise price of $12.57. 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. For the three and nine months ended September 30, 2014 and 2013, 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,
		2014			2013			2014			2013
	Risk-free interest rate		1.7	%		1.3	%		1.7	%		0.9	%
	Expected annual dividend yield		—			—			—			—
	Expected stock price volatility		69.8	%		71.3	%		70.9	%		63.2	%
	Expected term of options		5.0 years			4.7 years			5.1 years			4.9 years
	During the nine months ended September 30, 2014, options to purchase 421,540 shares of common stock were exercised, with a weighted-average exercise price of $7.05.
	Employee Stock Purchase Plan
	The weighted-average fair value of each purchase right granted during the nine months ended September 30, 2014 and 2013 was $5.66 and $8.68, respectively. For the nine months ended September 30, 2014 and 2013, the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions:
		Nine Months Ended			Nine Months Ended
		September 30, 2014			September 30, 2013
	Risk-free interest rate		0.3	%		0.3	%
	Expected annual dividend yield		—			—
	Expected stock price volatility		66.7	%		91.5	%
	Expected term of options		1.25 years			1.25 years

Cash_Cash_Equivalents_and_Avai

Cash, Cash Equivalents and Available-for-Sale Securities	9 Months Ended
	Sep. 30, 2014
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, 2014
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	321,257	$	—	$	—		$	321,257
	Available-for-sale securities:
	Corporate obligations due in one year or less		42,141		18		(2	)		42,157
	Mortgage-backed securities due after ten years		426		107		—			533
	U.S. government-sponsored enterprise obligations due in one year or less		15,580		8		—			15,588
	Total available-for-sale securities		58,147		133		(2	)		58,278
	Total cash, cash equivalents and available-for-sale securities	$	379,404	$	133	$	(2	)	$	379,535
		December 31, 2013
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	68,114	$	—	$	—		$	68,114
	Available-for-sale securities:
	Corporate obligations due in one year or less		103,889		18		(16	)		103,891
	Corporate obligations due in one to five years		13,513		32		—			13,545
	Mortgage-backed securities due after ten years		478		104		—			582
	U.S. government-sponsored enterprise obligations due in one year or less		24,144		13		—			24,157
	U.S. government-sponsored enterprise obligations due in one to five years		4,174		5		—			4,179
	Total available-for-sale securities		146,198		172		(16	)		146,354
	Total cash, cash equivalents and available-for-sale securities	$	214,312	$	172	$	(16	)	$	214,468
	We held three debt securities at September 30, 2014 that had been in an unrealized loss position for less than 12 months and no debt securities that had been in an unrealized loss position for 12 months or greater. The fair value on these securities was $6.9 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 three 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. Based on our analysis, we do not consider these investments to be other-than-temporarily impaired as of September 30, 2014.
	As of September 30, 2014, we held ten debt securities from financial institutions and other companies located in France, the Netherlands, the United Kingdom, Japan, Switzerland, Canada, Singapore and Sweden with a fair value of $27.5 million. There were no material unrealized losses incurred by these securities.
	We had no material realized gains or losses on our available-for-sale securities for the three and nine months ended September 30, 2014 and 2013. There were no other-than-temporary impairments recognized for the three and nine months ended September 30, 2014 and 2013.

Fair_Value

Fair Value	9 Months Ended
	Sep. 30, 2014
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. The classification of a financial asset or liability within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. 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, 2014 and December 31, 2013.
	The following table provides the assets carried at fair value measured on a recurring basis as of September 30, 2014:
			Level 1		Level 2
			(in thousands)
	Cash and cash equivalents		$	320,507	$	750
	Corporate obligations (including commercial paper)			—		42,157
	Mortgage-backed securities			—		533
	U.S. government-sponsored enterprise obligations			—		15,588
	Total		$	320,507	$	59,028
	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 the three month Treasury bill published on the 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 Takeda is recorded at its carrying value at September 30, 2014. The fair value of the amount due to Takeda, a Level 2 measurement, was approximately $6.6 million as of September 30, 2014 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, 2014 (see note 7).
	The carrying amounts reflected in the condensed consolidated balance sheets for prepaid expenses and other current assets, other assets, accounts payable and accrued expenses approximate their fair value due to their short term maturities.
	There have been no changes to the valuation methods during the nine months ended September 30, 2014. 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, 2014. We had no available-for-sale securities that were classified as Level 3 at any point during the nine months ended September 30, 2014 or during the year ended December 31, 2013.

Collaborations

Collaborations	9 Months Ended
	Sep. 30, 2014
Collaborations	'
	7. Collaborations
	AbbVie
	On September 2, 2014, we entered into a collaboration and license agreement with AbbVie Inc., or AbbVie, which we refer to as the AbbVie Agreement. Under the AbbVie Agreement, we will collaborate with AbbVie to develop and commercialize products containing duvelisib, which we refer to as Duvelisib Products, in oncology indications. Under the terms of the AbbVie Agreement, we have granted to AbbVie licenses under applicable patents, patent applications, know-how and trademarks to develop, commercialize and manufacture Duvelisib Products in oncology indications. These licenses are generally co-exclusive with rights we retain, except that we have granted AbbVie exclusive licenses to commercialize Duvelisib Products outside the United States. We and AbbVie retain the rights to perform our respective obligations and exercise our respective rights under the AbbVie Agreement, and we and AbbVie may each grant sublicenses to affiliates or third parties.
	Under the AbbVie Agreement, we and AbbVie have created a governance structure, including committees and working groups to manage the development, manufacturing and commercialization responsibilities for Duvelisib Products. Generally, we and AbbVie must mutually agree on decisions, although in specified circumstances either we or AbbVie would be able to break a deadlock.
	We and AbbVie share oversight of development and have each agreed to use diligent efforts, as defined in the AbbVie Agreement, to carry out our development activities under an agreed upon development plan. We have primary responsibility for the conduct of development of Duvelisib Products, except that AbbVie has responsibility for the conduct of certain contemplated combination clinical studies, which we refer to as the AbbVie Studies. We have the responsibility to manufacture Duvelisib Products until we transition manufacturing responsibility to AbbVie, which we expect to occur as promptly as practicable while ensuring continuity of supply. Excluding the AbbVie Studies, we are responsible for all costs to develop and manufacture Duvelisib Products up to a maximum amount of $667 million after which we will share Duvelisib Product development and manufacturing costs equally with AbbVie. The development and manufacturing costs for the AbbVie Studies will be shared equally.
	We and AbbVie share operational responsibility and decision making authority for commercialization of Duvelisib Products in the United States. Specifically, we have the primary responsibility for advertising, distribution, and booking sales, and we share certain other commercialization functions with AbbVie. Assuming regulatory approval, we and AbbVie will each provide half of the sales representative effort to promote Duvelisib Products in the United States. Outside the United States, AbbVie has, with limited exceptions, operational responsibility and decision making authority to commercialize Duvelisib Products. We and AbbVie will share the cost of manufacturing and supply for commercialization of Duvelisib Products in the United States and AbbVie will bear the cost of manufacturing and supply for commercialization of Duvelisib Products outside the United States. Prior to commercialization and regulatory approval, we will recognize these costs as a component of research and development and general and administrative expenses. Subsequent to regulatory approval and commercial launch, the cost of manufacturing will be recorded as cost of goods sold.
	AbbVie has paid us a non-refundable $275 million upfront payment and has agreed to pay us up to $530 million in potential future milestone payments comprised of $130 million associated with the achievement of a specified clinical development milestone, up to $275 million associated with the achievement of specified regulatory filing and approval milestones, and up to $125 million associated with the achievement of specified commercialization milestones. Under the terms of the AbbVie Agreement, we and AbbVie will equally share commercial profits or losses of Duvelisib Products in the United States, including sharing equally the existing royalty obligations to Mundipharma International Corporation Limited, or Mundipharma, and Purdue Pharmaceutical Products L.P., or Purdue, for sales of Duvelisib Products in the United States, as well as sharing equally the existing U.S. milestone payment obligations to Takeda. Additionally, AbbVie has agreed to pay us tiered royalties on net sales of Duvelisib Products outside the United States ranging from 23.5% to 30.5%, depending on annual net sales of Duvelisib Products by AbbVie, its affiliates and its sublicensees. We are responsible for the existing royalty obligations to Mundipharma and Purdue outside the United States and to Takeda worldwide, and AbbVie has agreed to reimburse us for our existing Duvelisib Product milestone payment obligations to Takeda outside the United States. The tiered royalty from AbbVie is subject to a reduction of 4% at each tier if our royalties to Mundipharma and Purdue are reduced according to the terms of our respective agreements with them. This tiered royalty can further be reduced based on specified factors, including patent expiry, generic entry, and royalties paid to third parties with blocking intellectual property. These royalties are payable on a product-by-product and country-by-country basis until AbbVie ceases selling the product in the country.
	We have evaluated the deliverables within the AbbVie Agreement to determine whether or not they provide value on a standalone basis. Based on our evaluation, we have determined that there are three deliverables: the license, the development services and the committee services, and each provides value on a stand-alone basis and represents a separate unit of accounting. We determined the best estimate of selling price for each unit of accounting using a discounted cash-flow model. The valuation for each deliverable involves significant estimates and assumptions, including but not limited to, expected market opportunity, assumed royalty rates, pricing objectives, clinical trial timelines, likelihood of success and projected costs. The resulting estimate of selling prices for the license and development services consider the benefits that have been retained by the Company.
	Of the $275 million upfront payment received during the three months ended September 30, 2014, $159.1 million was allocated to the license, $115.6 million to the development services and $0.3 million to committee services. We recognized license revenue upon execution of the arrangement. Revenue related to development services and committee services are being recognized using the proportionate performance method as services are provided over the estimated service period of approximately five years. During the three and nine months ended September 30, 2014, we recognized $159.1 million of revenue related to the license and $1.5 million of revenue related to development and committee services. We have recorded the remaining amount of $114.4 million related to development and committee services as deferred revenue as of September 30, 2014.
	The development, regulatory and commercialization milestones represent non-fundable amounts that would be paid by AbbVie to us if certain milestones are achieved in the future. We have elected to apply the milestones method of revenue recognition to these milestones. We have determined that all milestones, except for the first milestone, if achieved, are substantive as they relate solely to past performance, are commensurate with estimated enhancement of value associated with the achievement of each milestone as a result of our performance, which are reasonable relative to other deliverables and terms of the arrangement, and are unrelated to the delivery of any further elements under the arrangement. The clinical development milestone, which we have determined not to be substantive based on risk and effort involved, will be recognized using the same method as the upfront payment when achieved.
	Subject to limited exceptions, we have agreed that we and our affiliates will not commercialize, or assist others in commercializing, in oncology indications any product that is a PI3K delta, gamma inhibitor that meets certain agreed-to criteria, other than Duvelisib Products, and AbbVie has agreed to similar restrictions. Registration directed clinical trials and commercialization of Duvelisib Products for uses outside of oncology indications would require our and AbbVie’s mutual consent.
	The AbbVie Agreement will remain in effect until all development, manufacturing and commercialization of Duvelisib Products cease, unless terminated earlier. Either we or AbbVie may terminate the AbbVie Agreement if the other party is subject to certain insolvency proceedings or if the other party materially breaches the AbbVie Agreement and the breach remains uncured for a specified period, which may be extended in certain circumstances. However, we may terminate the AbbVie Agreement only on a country by country basis in the event AbbVie is not using diligent efforts to obtain regulatory approval or to commercialize Duvelisib Products in a country outside the United States. AbbVie may also terminate the AbbVie Agreement for convenience after a specified notice period. In the event there is a material uncured breach by either us or AbbVie of development or commercialization obligations, the non-breaching party may also have the right to assume and conduct such applicable development or commercialization obligations. If AbbVie or any of its affiliates or sublicensees challenges the patents we have licensed to AbbVie, we can terminate the AbbVie Agreement if the challenge is not withdrawn after a specified notice period.
	If the AbbVie Agreement is terminated, we would receive all rights to the regulatory filings related to duvelisib upon our request, our license to AbbVie would terminate, and AbbVie would grant us a perpetual, irrevocable license to develop, manufacture and commercialize products containing duvelisib, excluding any compound which is covered by patent rights controlled by AbbVie or its affiliates. This license would be royalty free, unless the AbbVie Agreement is terminated for material breach, in which case, depending on the breaching party and the timing of the material breach, a royalty rate may be payable by us ranging from a low single-digit percentage to a low double-digit percentage of net sales, and, in some cases, subject to a payment cap.
	If the AbbVie Agreement is terminated, there are certain wind-down obligations to ensure a smooth transition of the responsibilities of the parties including, unless the AbbVie Agreement is terminated by AbbVie for our material breach, the continued conduct of certain development and commercialization activities by AbbVie for a limited transition period and the continued funding by AbbVie of its half of the cost of the AbbVie Studies ongoing at the time of termination.
	Takeda
	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 duvelisib, and we 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 Takeda. In December 2012, we amended and restated our development and license agreement with Takeda.
	Under the terms of the amended and restated agreement, we retained worldwide development rights and, in exchange for an agreement to pay Takeda $15 million in installments, we regained commercialization rights for products arising from the agreement for all therapeutic indications and are solely responsible for research conducted under the agreement. 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. During the nine months ended September 30, 2014, we paid to Takeda the second installment of $6.7 million. The remaining amount is due in January 2015, which we recorded as short-term liability due to Takeda on our condensed consolidated balance sheet.
	In addition to developing duvelisib, we are seeking to develop our second potent, oral PI3K delta, gamma inhibitor product candidate, 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 Takeda up to $5 million in remaining success-based milestone payments for the development of two distinct product candidates and up to $450 million in success-based milestones for the approval and commercialization of two distinct products. In February 2014, we paid Takeda a $10 million milestone payment in connection with the initiation of our Phase 3 study of duvelisib in patients with relapsed or refractory chronic lymphocytic leukemia, or CLL. We recognized the $10 million payment as research and development expense during the nine months ended September 30, 2014. In addition, we are obligated to pay Takeda tiered royalties on worldwide net sales ranging from 7% to 11% 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 of the royalties, and, in certain circumstances, limits on the number of products subject to a royalty obligation.
	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. Takeda 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 Takeda, demonstrate to Takeda’s reasonable satisfaction that we have not failed to be diligent. The foregoing periods are subject to extension in certain circumstances. Additionally, Takeda 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.
	On July 29, 2014, we entered into an amendment to our agreement with Takeda, or the 2014 Takeda Amendment. Under the 2014 Takeda Amendment, we paid to Takeda a one-time upfront payment of $5 million in exchange for the option to terminate our royalty obligations to Takeda under the amended and restated agreement solely with respect to worldwide net sales in oncology indications of products containing or comprised of duvelisib. The option may be exercised by payment to Takeda of a fee of $52.5 million on or before March 31, 2015. If the option is not exercised, our royalty obligations to Takeda will remain unchanged. We recognized the $5 million upfront payment as research and development expense during the three months ended September 30, 2014 as there is no alternative future use beyond the existing research and development activities.
	FAAH Program License
	In August 2014, we licensed rights to our fatty acid amide hydrolase, or FAAH program, to FAAH Pharma Inc., or FAAH Pharma, a start-up company pursuing the clinical development of IPI-940 to investigate its potential to treat neuropathic pain. We received a 23% ownership in FAAH Pharma in exchange for the license. FAAH Pharma receives funding from TVM Life Science Ventures VII, L.P., or TVM, under potential milestone payments. We have elected to use the carryover basis of measurement and no gain or loss is recognized related to this transaction.
	Mundipharma and Purdue
	Strategic Alliance Termination Agreements
	On July 17, 2012, we terminated our strategic alliance with Mundipharma International Corporation Limited, or Mundipharma, and Purdue Pharmaceutical Products L.P., or Purdue, and we entered into termination and revised relationship agreements with each of those entities, which we refer to as the 2012 Termination Agreements. We considered Mundipharma, Purdue and their respective associated entities to be related parties for financial reporting purposes prior to April 2013 because of their equity ownership in us. The strategic 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 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.
	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 strategic alliance, Mundipharma was obligated to reimburse us for research and development expenses we incurred, up to an annual aggregate cap for each strategic alliance program other than FAAH. 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 4% 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 1% 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 that were subject to the alliance, which products require 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%. 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% 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., or PPLP, that provided for the borrowing by us of one or more unsecured loans up to an aggregate maximum principal amount of $50 million. 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
	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 and, in connection therewith, to grant various rights to the BRP entities. The consideration was composed of extinguishment of approximately $51 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.
	April 2013 Offering and 2013 Termination Agreement
	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.

Debt_Facility_Agreement

Debt Facility Agreement	9 Months Ended
	Sep. 30, 2014
Debt Facility Agreement	'
	8. Debt Facility Agreement
	On February 24, 2014, we entered into a facility agreement with affiliates of Deerfield Management Company, L.P., or Deerfield, pursuant to which, Deerfield agreed to loan us up to $100 million, subject to the terms and conditions set forth in the facility agreement. On September 22, 2014, we amended the facility agreement with Deerfield such that the maximum principal amount that we may draw down is reduced to $50 million. We refer to the facility agreement with Deerfield, as amended, as the Facility Agreement.
	Under the terms of the Facility Agreement, we may draw down on the Facility Agreement in $25 million minimum disbursements, which we refer to as the Loan Commitment, at any time on 22 business days prior notice until February 27, 2015, which we refer to as the Draw Period. Our ability to draw down under the Facility Agreement is subject to various customary conditions, including the entry into a Guaranty and Security Agreement, or Guaranty, with Deerfield and Infinity Discovery, Inc., or IDI, our a wholly-owned subsidiary, pursuant to which, as security for the repayment of our obligations under the Facility Agreement, IDI will guaranty all our obligations under the Facility Agreement and, to secure the obligations under the Facility Agreement and the Guaranty, both we and IDI will grant to Deerfield a security interest in substantially all our assets including intellectual property.
	Any amounts drawn under the Facility Agreement accrue interest at a rate of 7.95% per annum, and such interest shall be payable quarterly in arrears on the first day of each June, September, December and March following the disbursement date, provided that, subject to the next sentence, during the first five interest payment dates of any draw under the Facility Agreement, we may elect to pay all or a portion of such accrued interest by adding it to the principal amount outstanding. All such accrued interest will, regardless of which draw it applies to, be payable on the last business day of the sixth calendar quarter following the date of the first draw under the Facility Agreement. We have the right to terminate the Facility Agreement and/or to prepay amounts owed under the Facility Agreement at any time, provided that, to the extent that any amount was drawn less than three years before such early termination or prepayment, we will be required to pay an additional amount equal to three years of interest on the amount being prepaid less the amount of interest previously paid on such amount. For amounts drawn under the Facility Agreement, we will be required to repay them to Deerfield in installments equal to one-third of the outstanding amount of the total principal amount drawn under the Facility Agreement on each of the third, fourth and fifth anniversaries of the first draw; the final payment, however, must be made by December 15, 2019. On February 27, 2015, or upon the earlier termination or acceleration of the facility, we are required to pay a fee equal to three percent of the difference between the $50 million commitment and the aggregate amount of disbursements under the Facility Agreement made prior to such date, which we refer to as the Facility Fee. As of September 30, 2014, we have not drawn under the Facility Agreement and have determined it probable that we will be required to pay the full Facility Fee amount of $1.5 million on February 27, 2015. We have recorded the full $1.5 million Facility Fee on the September 30, 2014 condensed consolidated balance sheet as a component of both the loan commitment asset and accrued expenses line items. The loan commitment asset is being amortized to interest expense in the condensed consolidated statements of operations and comprehensive loss on a straight line basis over the Draw Period.
	Deerfield will have the right to accelerate payment of the facility in the event that we consummate a major transaction, which is generally defined as a change in control, a sale of all or substantially all of our assets, a tender or exchange offer for our common stock, a liquidation, bankruptcy, insolvency, dissolution or wind up, a delisting and/or the common stock ceases to be registered under the Securities Exchange Act of 1934, or the Exchange Act. Any amounts drawn under the Facility Agreement may become immediately due and payable upon (i) customary events of default, as defined in the Facility Agreement, or (ii) the consummation of certain major transactions, in which case Deerfield would have the right to require us to repay 100% of the principal amount of the loan, plus any accrued and unpaid interest thereon, plus any applicable additional amounts relating to a prepayment or termination, as described above.
	Principal and interest under the Facility Agreement may be paid in cash or freely tradable shares of common stock at our election, subject to specified conditions at any time of conversion. The Facility Agreement contains various representations and warranties, and affirmative covenants customary for agreements of this type, including the requirement that we maintain at all times a cash, cash equivalents and available-for-sale securities balance of not less than $25 million, as well as negative covenants customary for financings of this type that are applicable upon the first draw under the Facility Agreement. Additionally, the Facility Agreement contains conditions that must be met prior to disbursements, including the condition that the number of shares of our common stock issued or issuable pursuant to all warrants following the proposed disbursement, together with payments made in our common stock under the Facility Agreement, will not exceed 9,500,000 shares, subject to appropriate adjustment to reflect any stock splits, stock combination, reclassification or similar adjustments in the number of outstanding shares of common stock.
	Our total cost of securing the Loan Commitment was $11.8 million and is comprised of $8.4 million representing the fair value of the 1,000,000 warrants issued on February 24, 2014, discussed below; $3 million representing the Facility Fee; and $0.4 million of transaction costs. As a result of the amendment of the Facility Agreement, we reduced the Facility Fee by 50%, or $1.5 million and recorded a corresponding decrease in the loan commitment asset. In addition, since our borrowing capacity was reduced by 50%, the remaining loan commitment asset outstanding as of September 22, 2014 was also reduced by 50% resulting in an additional expense of $1.8 million during the three months ended September 30, 2014. The total fair value, a Level 2 measurement, is considered a Loan Commitment Asset which has been classified as a current asset on the September 30, 2014 condensed consolidated balance sheets. This amount is considered a fee to secure the Loan Commitment and is being amortized to interest expense in the three and nine months ended September 30, 2014 condensed consolidated statements of operations and comprehensive loss on a straight line basis over the Draw Period. We recorded $4.5 million and $8.6 million of interest expense associated with the amortization and write-off of the loan commitment asset pursuant to the modification of the facility for the three and nine months ended September 30, 2014, respectively.
	In connection with the execution of the Facility Agreement, we issued to Deerfield warrants to purchase an aggregate of 1,000,000 shares of common stock at an exercise price of $13.83 per share, or the Initial Warrants. As noted above, pursuant to the Facility Agreement, we have the right to request from Deerfield one or more cash disbursements in the minimum amount of $25 million per disbursement, which disbursements shall be accompanied by the issuance to Deerfield of warrants, which we refer to as the Draw Warrants, to purchase an aggregate number of shares of common stock equal to 50% times the quotient of the amount of such disbursement divided by an exercise price equal to the average daily volume weighted average price per share of our common stock for a period of 20 consecutive trading days following Deerfield’s receipt of the applicable disbursement request. We refer to the Initial Warrants and the Draw Warrants individually as a Warrant or together as the Warrants. The maximum number of shares of our common stock issued or issuable pursuant to all Warrants and payments made in our common stock under the Facility Agreement is 9,500,000, subject to appropriate adjustment to reflect any stock splits, stock combination, reclassification or similar adjustments in the number of outstanding shares of common stock. The Warrants have dividend rights to the same extent as if the Warrants were exercised into shares of common stock.
	Each Warrant expires on the seventh anniversary of its issuance and contains certain limitations that prevent the holder from acquiring shares upon exercise of a Warrant that would result in the number of shares beneficially owned by it exceeding 9.985% of the total number of shares of common stock then issued and outstanding.
	In connection with the entry into the Facility Agreement and issuance of the Initial Warrants, we entered into a Registration Rights Agreement with Deerfield dated February 24, 2014. Pursuant to the terms of the Registration Rights Agreement, we filed, and on May 1, 2014 the Securities and Exchange Commission declared effective, a registration statement on Form S-3 registering for resale the 1,000,000 shares of common stock issuable upon the exercise of the Initial Warrants. Additionally, pursuant to the terms of the Registration Rights Agreement, we agreed to file one or more additional registration statements with the SEC to register for resale the shares of common stock issuable upon the exercise of the applicable Draw Warrants, on or prior to 30 days after issuance of each of the Draw Warrants.

Accrued_Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2014
Accrued Expenses	'
	9. Accrued Expenses
	Accrued expenses consisted of the following:
		September 30,		December 31,
		2014		2013
		(in thousands)
	Accrued compensation and benefits	$	7,041	$	1,839
	Accrued clinical studies		4,372		4,009
	Accrued drug manufacturing costs		2,368		991
	Accrued preclinical studies		432		303
	Facility fee		1,500		—
	Other		3,051		2,022
	Total accrued expenses	$	18,764	$	9,164

Lease

Lease	9 Months Ended
	Sep. 30, 2014
Lease	'
	10. Lease
	On September 25, 2014, we entered into a lease agreement, or the Lease, with BHX, LLC, as trustee of 784 Realty Trust, or the Landlord, for the lease of office space at 784 Memorial Drive, Cambridge, Massachusetts. The term of the Lease commences on November 1, 2014, which we refer to as the Commencement Date, and expires on March 31, 2025, or the Expiration Date, approximately ten years after the Commencement Date. Pursuant to the Lease, on the Commencement Date we have agreed to lease 61,000 square feet of the leased premises, which represents the entire building.
	From the Commencement Date until April 1, 2015, the total base rent of the Lease will be $0.00 per month. From April 1, 2015 through March 31, 2020, the total base rent of the Lease will be $170,291.67 per month. From April 1, 2020 until the Expiration Date, the total base rent of the Lease will be $190,625.00 per month. In addition to the base rent, we are also responsible for our share of the operating expenses, utility costs and real estate taxes, in accordance with the terms of the Lease. Pursuant to the terms of the Lease, we must provide a security deposit in cash or in the form of a letter of credit in the initial amount $1 million, which may be reduced by up to $750,000 over time in accordance with the terms of the Lease. The Landlord has agreed to pay up to $5,856,100 for certain updates and repairs to be made to the Leased Premises. We are responsible for the construction and bear the risk of cost over-runs.
	We have two consecutive rights to extend the term of the Lease for five years under each extension, provided that we provide notice to the Landlord no earlier than 18 months nor later than 12 months prior to expiration of the Lease. The base rent for each extension term shall be equal to 95% of the then fair market base rent per square foot for the premises.
	The Lease contains customary provisions allowing the Landlord to terminate the lease if we fail to remedy a default of any of its obligations under the Lease within specified time periods or upon bankruptcy or insolvency of us.
	Upon lease commencement, the building will undergo construction to suit our future needs. We will be involved in the construction project, including having responsibility to pay for a portion of the structural elements of the building and bear the risk of cost over-runs, and therefore we will be deemed for accounting purposes to be the owner of the building during the construction period. Accordingly, we will determine the fair value of the building and record it as an asset on our condensed consolidated balance sheet in November 2014, when the construction and lease commences. We will record project construction costs as an asset during the construction period and a corresponding construction financing obligation on the condensed consolidated balance sheets.
	We expect to bifurcate our future lease payments into a portion that is allocated to the building and a portion that is allocated to the land on which the building is located. The portion of the lease obligations allocated to the land will be treated for accounting purposes as an operating lease commencing in November 2014.
	The rent commencement date is April 1, 2015, which provides us a rent free period of five months. Upon signing the lease agreement on September 25, 2014, we paid the first month’s rent in the amount of $170,291, which we have recorded as a prepaid expense on the accompanying condensed consolidated balance sheets. In addition, we provided a letter of credit in the amount of $1.0 million to our landlord as security for the lease. The letter of credit plus the associated bank fee of $30,000 has been recorded in our accompanying condensed consolidated balance sheets as restricted cash.
	Future minimum payments, excluding operating costs and taxes, under the Lease, are as follows:
		Facility Leases
		(in thousands)
	Years Ending December 31:
	2015	$	1,362
	2016		2,044
	2017		2,044
	2018		2,044
	2019		2,044
	2020 and beyond		11,947
	Total minimum lease payments	$	21,485

Subsequent_Event

Subsequent Event	9 Months Ended
	Sep. 30, 2014
Subsequent Event	'
	11. Subsequent Event
	On November 6, 2014, we entered into a Seventh Amendment to Lease, or the Lease Amendment, by and between us and ARE-770/784/790 Memorial Drive, LLC, or the Landlord, which amends that Lease Agreement originally dated July 2, 2002, as amended to date, which we refer to as the Original Lease. We shall refer to the Original Lease together with the Lease Amendment as the Memorial Drive Lease. We shall refer to the area rented under the Memorial Drive Lease as the Premises.
	Under the Lease Amendment: (i) the Premises consist of 54,861 square feet, of which 3,861 square feet are located at 790 Memorial Drive, or the 790 Premises; we surrendered 13,159 square feet of the previously leased 17,020 square feet at the 790 Premises; (ii) we have extended the base term of the Memorial Drive Lease through March 31, 2025; and (iii) we have two separate five-year options to extend the term of the Memorial Drive Lease to 2035 on the same terms and conditions (other than with respect to base rent or any work letter). The Memorial Drive Lease provides that we shall continue to pay the base rent as provided in the Original Lease until January 31, 2016. The base rent shall then increase to $69.00 per square foot of the Premises on February 1, 2016 and again to $70.00 per square foot of the Premises on February 1, 2018. The Memorial Drive Lease provides that no base rent for the Premises shall be due (i) for the period commencing on February 1, 2015 through July 31, 2015, (ii) for the period commencing on February 1, 2016 through February 29, 2016, (iii) for the period commencing on February 1, 2017 through February 28, 2017, and (iv) for the period commencing on February 1, 2018 through February 28, 2018. We have also received a base building allowance of $1,097,220, or $20.00 per square foot, for the design and construction of capital improvements to the 780 Premises and a tenant improvement allowance of $1,920,135, or $35.00 per square foot, for the design and construction of additional alterations to the Premises.
	We are currently evaluating the accounting for this transaction, which will be reflected in our Form 10-K for the fiscal year ending December 31, 2014.

Significant_Accounting_Policie1

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2014
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 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 or 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, 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, 2014 and December 31, 2013 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, 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 investment and other income. The cost of securities sold is based on the specific identification method. We include in investment and other 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 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.
	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 decline in fair value of the security 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.
Basic and Diluted Loss per Common Share	'
	Basic and Diluted Net 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 and the exercise of outstanding warrants (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. The two-class method is used for outstanding warrants as it is considered to be a participating security and it is more dilutive than the treasury stock method. The following outstanding shares of common stock equivalents were excluded from the computation of net income (loss) per share attributable to common stockholders for the periods presented because including them would have been antidilutive:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
			2014			2013			2014			2013
	Stock Options			3,711,997			6,255,772			3,715,825			6,255,772
	Warrants (excluded from treasury stock method)			1,000,000			—			1,000,000			—
	Basic and diluted earnings (loss) per common share were determined as follows:
			Three Months Ended						Nine Months Ended
			September 30,						September 30,
			2014			2013			2014			2013
			(in thousands, except share and per share amounts)
	Basic
	Net income (loss)		$	103,217		$	(33,938	)	$	22,926		$	(93,855	)
	Undistributed earnings allocated to warrants			(2,080	)		—			(362	)		—
	Net income (loss)		$	101,137		$	(33,938	)	$	22,564		$	(93,855	)
	Weighted average common shares outstanding			48,632,888			48,052,939			48,497,305			47,875,706
	Basic earnings (loss) per common share		$	2.08		$	(0.71	)	$	0.47		$	(1.96	)
	Diluted
	Net income (loss)		$	103,217		$	(33,938	)	$	22,926		$	(93,855	)
	Undistributed earnings allocated to warrants			(2,034	)		—			(354	)		—
	Net income (loss)		$	101,183		$	(33,938	)	$	22,572		$	(93,855	)
	Weighted average common shares outstanding			48,632,888			48,052,939			48,497,305			47,875,706
	Effect of dilutive options			1,102,415			—			1,035,817			—
	Weighted average common shares outstanding assuming dilution			49,735,303			48,052,939			49,533,122			47,875,706
	Diluted earnings (loss) per common share		$	2.03		$	(0.71	)	$	0.46		$	(1.96	)
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, 2014, 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, or 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. 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. For awards with performance conditions, we estimate the likelihood of satisfaction of the performance conditions, which affects the period over which the expense is recognized, and recognize the expense over the requisite service period on a straight-line basis. We have no awards with market 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, upfront license fees, funding or reimbursement of research and development efforts, milestone payments if specified objectives are achieved, and/or royalties on product sales. We evaluate all deliverables within an arrangement to determine whether or not they provide value on a stand-alone basis. Based on this evaluation, the deliverables are separated into units of accounting. For each unit of accounting identified within an arrangement, we determine the period over which the performance obligation occurs. Revenue is then recognized using the proportional performance method. The proportional performance method is used when the level of effort to complete the performance obligations under an arrangement can be reasonably estimated. 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. The process for determining the best estimate of the selling price involves significant judgment and estimates.
	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.
	In making this assessment, 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. 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.
	We will recognize royalty revenue, if any, based upon actual and estimated net sales by the licensee of licensed products in licensed territories, and 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, comparator drug expenses, stock-based compensation expense, depreciation of equipment, contract services, and other outside expenses. We also include as research and development expense upfront 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. Prepaid comparator drug expenses are capitalized and then recognized as expense when title transfers to us. 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 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., or 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, or Takeda, acting through its Millennium business unit. We refer to our phosphoinositide-3-kinase, or P13K, program licensor as Takeda.
Income Taxes	'
	Income Taxes
	We use the liability method to account for income taxes. Deferred tax assets and liabilities are determined based on temporary 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, 2014 and December 31, 2013.
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 Takeda 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 is recorded as depreciation expense and included in research and development and general and administrative 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, 2014
Summary Of Outstanding Shares Of Common Stock Equivalents Excluded From Computation Of Net Income (Loss) Per Share Attributable To Common Stockholders	'
	The following outstanding shares of common stock equivalents were excluded from the computation of net income (loss) per share attributable to common stockholders for the periods presented because including them would have been antidilutive:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Stock Options		3,711,997			6,255,772			3,715,825			6,255,772
	Warrants (excluded from treasury stock method)		1,000,000			—			1,000,000			—
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,
		2014			2013			2014			2013
		(in thousands, except share and per share amounts)
	Basic
	Net income (loss)	$	103,217		$	(33,938	)	$	22,926		$	(93,855	)
	Undistributed earnings allocated to warrants		(2,080	)		—			(362	)		—
	Net income (loss)	$	101,137		$	(33,938	)	$	22,564		$	(93,855	)
	Weighted average common shares outstanding		48,632,888			48,052,939			48,497,305			47,875,706
	Basic earnings (loss) per common share	$	2.08		$	(0.71	)	$	0.47		$	(1.96	)
	Diluted
	Net income (loss)	$	103,217		$	(33,938	)	$	22,926		$	(93,855	)
	Undistributed earnings allocated to warrants		(2,034	)		—			(354	)		—
	Net income (loss)	$	101,183		$	(33,938	)	$	22,572		$	(93,855	)
	Weighted average common shares outstanding		48,632,888			48,052,939			48,497,305			47,875,706
	Effect of dilutive options		1,102,415			—			1,035,817			—
	Weighted average common shares outstanding assuming dilution		49,735,303			48,052,939			49,533,122			47,875,706
	Diluted earnings (loss) per common share	$	2.03		$	(0.71	)	$	0.46		$	(1.96	)
Property and Equipment, Depreciated 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, 2014
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, 2014 and 2013 comprised the following:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
		(in thousands)
	Effect of stock-based compensation on net loss by line item:
	Research and development	$	1,760		$	1,599		$	5,736		$	4,618
	General and administrative		1,172			1,660			3,887			4,717
Black-Scholes Valuation Model, Weighted-Average Assumptions for Stock Options	'
	For the three and nine months ended September 30, 2014 and 2013, 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,
		2014			2013			2014			2013
	Risk-free interest rate		1.7	%		1.3	%		1.7	%		0.9	%
	Expected annual dividend yield		—			—			—			—
	Expected stock price volatility		69.8	%		71.3	%		70.9	%		63.2	%
	Expected term of options		5.0 years			4.7 years			5.1 years			4.9 years
Black-Scholes Valuation Model, Weighted-Average Assumptions for Employee Stock Purchase Plan	'
	For the nine months ended September 30, 2014 and 2013, the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions:
		Nine Months Ended			Nine Months Ended
		September 30, 2014			September 30, 2013
	Risk-free interest rate		0.3	%		0.3	%
	Expected annual dividend yield		—			—
	Expected stock price volatility		66.7	%		91.5	%
	Expected term of options		1.25 years			1.25 years

Cash_Cash_Equivalents_and_Avai1

Cash, Cash Equivalents and Available-for-Sale Securities (Tables)	9 Months Ended
	Sep. 30, 2014
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, 2014
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	321,257	$	—	$	—		$	321,257
	Available-for-sale securities:
	Corporate obligations due in one year or less		42,141		18		(2	)		42,157
	Mortgage-backed securities due after ten years		426		107		—			533
	U.S. government-sponsored enterprise obligations due in one year or less		15,580		8		—			15,588
	Total available-for-sale securities		58,147		133		(2	)		58,278
	Total cash, cash equivalents and available-for-sale securities	$	379,404	$	133	$	(2	)	$	379,535
		December 31, 2013
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	68,114	$	—	$	—		$	68,114
	Available-for-sale securities:
	Corporate obligations due in one year or less		103,889		18		(16	)		103,891
	Corporate obligations due in one to five years		13,513		32		—			13,545
	Mortgage-backed securities due after ten years		478		104		—			582
	U.S. government-sponsored enterprise obligations due in one year or less		24,144		13		—			24,157
	U.S. government-sponsored enterprise obligations due in one to five years		4,174		5		—			4,179
	Total available-for-sale securities		146,198		172		(16	)		146,354
	Total cash, cash equivalents and available-for-sale securities	$	214,312	$	172	$	(16	)	$	214,468

Fair_Value_Tables

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2014
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, 2014:
		Level 1		Level 2
		(in thousands)
	Cash and cash equivalents	$	320,507	$	750
	Corporate obligations (including commercial paper)		—		42,157
	Mortgage-backed securities		—		533
	U.S. government-sponsored enterprise obligations		—		15,588
	Total	$	320,507	$	59,028

Accrued_Expenses_Tables

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2014
Accrued Expenses	'
	Accrued expenses consisted of the following:
		September 30,		December 31,
		2014		2013
		(in thousands)
	Accrued compensation and benefits	$	7,041	$	1,839
	Accrued clinical studies		4,372		4,009
	Accrued drug manufacturing costs		2,368		991
	Accrued preclinical studies		432		303
	Facility fee		1,500		—
	Other		3,051		2,022
	Total accrued expenses	$	18,764	$	9,164

Lease_Tables

Lease (Tables)	9 Months Ended
	Sep. 30, 2014
Future Minimum Payments Under Facility Leases	'
	Future minimum payments, excluding operating costs and taxes, under the Lease, are as follows:
		Facility Leases
		(in thousands)
	Years Ending December 31:
	2015	$	1,362
	2016		2,044
	2017		2,044
	2018		2,044
	2019		2,044
	2020 and beyond		11,947
	Total minimum lease payments	$	21,485

Significant_Accounting_Policie3

Significant Accounting Policies - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014
	Segment
Significant Accounting Policies [Line Items]	'
Number of operating segments	1
Reclassifications out of accumulated other comprehensive income loss	$0
Maximum	'
Significant Accounting Policies [Line Items]	'
Maturity of highly liquid investments	'3 months

Summary_Of_Outstanding_Shares_

Summary Of Outstanding Shares Of Common Stock Equivalents Excluded From Computation Of Net Income (Loss) Per Share Attributable To Common Stockholders (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock Options	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Common equivalent shares excluded from computation of earnings per share, amount	3,711,997	6,255,772	3,715,825	6,255,772
Warrants (excluded from treasury stock method)	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Common equivalent shares excluded from computation of earnings per share, amount	1,000,000	'	1,000,000	'

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, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Basic	'	'	'	'
Net income (loss)	$103,217	($33,938)	$22,926	($93,855)
Undistributed earnings allocated to warrants basic	-2,080	'	-362	'
Net income (loss)	101,137	-33,938	22,564	-93,855
Weighted average common shares outstanding	48,632,888	48,052,939	48,497,305	47,875,706
Basic earnings (loss) per common share	$2.08	($0.71)	$0.47	($1.96)
Diluted	'	'	'	'
Net income (loss)	103,217	-33,938	22,926	-93,855
Undistributed earnings allocated to warrants diluted	-2,034	'	-354	'
Net income (loss)	$101,183	($33,938)	$22,572	($93,855)
Weighted average common shares outstanding	48,632,888	48,052,939	48,497,305	47,875,706
Effect of dilutive options	1,102,415	'	1,035,817	'
Weighted average common shares outstanding assuming dilution	49,735,303	48,052,939	49,533,122	47,875,706
Diluted earnings (loss) per common share	$2.03	($0.71)	$0.46	($1.96)

Property_and_Equipment_Depreci

Property and Equipment, Depreciation Periods (Detail)	9 Months Ended
	Sep. 30, 2014
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, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Research and Development	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]	'	'	'	'
Effect of stock-based compensation on net loss	$1,760	$1,599	$5,736	$4,618
General and Administrative	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]	'	'	'	'
Effect of stock-based compensation on net loss	$1,172	$1,660	$3,887	$4,717

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
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	$19.80	'
Unrecognized compensation cost, weighted-average recognition period	'2 years 4 months 24 days	'
Stock options exercised	421,540	'
Stock options exercised, weighted average exercise price	$7.05	'
Stock Options	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Stock options granted	1,532,384	1,371,094
Stock options granted, weighted average fair value	$7.43	$18.35
Stock options granted, weighted average exercise price	$12.57	$33.09
Employee Stock Purchase Plan	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Stock options granted, weighted average fair value	$5.66	$8.68

BlackScholes_Valuation_Model_W

Black-Scholes Valuation Model, Weighted-Average Assumptions (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock Options	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Risk-free interest rate	1.70%	1.30%	1.70%	0.90%
Expected annual dividend yield	'	'	'	'
Expected stock price volatility	69.80%	71.30%	70.90%	63.20%
Expected term of options	'5 years	'4 years 8 months 12 days	'5 years 1 month 6 days	'4 years 10 months 24 days
Employee Stock Purchase Plan	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Risk-free interest rate	'	'	0.30%	0.30%
Expected annual dividend yield	'	'	'	'
Expected stock price volatility	'	'	66.70%	91.50%
Expected term of options	'	'	'1 year 3 months	'1 year 3 months

Summary_of_Cash_Cash_Equivalen

Summary of Cash, Cash Equivalents and Available-for-sale Securities (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Cash and cash equivalents due in 90 days or less, Cost	$321,257	$68,114	'	'
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	321,257	68,114	53,478	175,742
Total available-for-sale securities, Cost	58,147	146,198	'	'
Total available-for-sale securities, Gross Unrealized Gains	133	172	'	'
Total available-for-sale securities, Gross Unrealized Losses	-2	-16	'	'
Total available-for-sale securities, Estimated Fair Value	58,278	146,354	'	'
Total cash, cash equivalents and available-for-sale securities, Cost	379,404	214,312	'	'
Total cash, cash equivalents and available-for-sale securities, Gross Unrealized Gains	133	172	'	'
Total cash, cash equivalents and available-for-sale securities, Gross Unrealized Losses	-2	-16	'	'
Total cash, cash equivalents and available-for-sale securities	379,535	214,468	'	'
Mortgage-Backed Securities	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available-for-sale securities due after ten years, Cost	426	478	'	'
Available-for-sale securities due after ten years, Gross Unrealized Gains	107	104	'	'
Available-for-sale securities, after ten years, Gross Unrealized Losses	'	'	'	'
Available-for-sale securities due after ten years, Estimated Fair Value	533	582	'	'
Corporate Obligations	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available-for-sale securities, due in one year or less, Cost	42,141	103,889	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Gains	18	18	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Losses	-2	-16	'	'
Available-for-sale securities, due in one year or less, Estimated Fair Value	42,157	103,891	'	'
Available-for-sale securities, due in one to five years, Cost	'	13,513	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Gains	'	32	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Losses	'	'	'	'
Available-for-sale securities, due in one to five years, Estimated Fair Value	'	13,545	'	'
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	15,580	24,144	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Gains	8	13	'	'
Available-for-sale securities, due in one year or less, Estimated Fair Value	15,588	24,157	'	'
Available-for-sale securities, due in one to five years, Cost	'	4,174	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Gains	'	5	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Losses	'	'	'	'
Available-for-sale securities, due in one to five years, Estimated Fair Value	'	$4,179	'	'

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, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available for sale securities debt fair value	$6,900,000	'	$6,900,000	'
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	3	'	3	'
12 months or greater	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Number of debt securities held in an unrealized loss position	0	'	0	'
Foreign Financial Institution and Other Corporate Debt Securities	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available for sale securities number of financial institution debt securities and other corporate debt securities located in foreign countries	10	'	10	'
Available for sale securities debt fair value	$27,500,000	'	$27,500,000	'

Assets_Carried_at_Fair_Value_M

Assets Carried at Fair Value Measured on Recurring Basis (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
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	$379,535	$214,468
Level 1	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	320,507	'
Corporate obligations (including commercial paper)	'	'
Mortgage-backed securities	'	'
U.S. government-sponsored enterprise obligations	'	'
Total cash, cash equivalents and available-for-sale securities	320,507	'
Level 2	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	750	'
Corporate obligations (including commercial paper)	42,157	'
Mortgage-backed securities	533	'
U.S. government-sponsored enterprise obligations	15,588	'
Total cash, cash equivalents and available-for-sale securities	$59,028	'

Fair_Value_Additional_Informat

Fair Value - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available-for-sale securities	$58,278,000	$146,354,000
Transfers of assets or liabilities between Level 1 and Level 2	0	'
Fair Value, Inputs, Level 3	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available-for-sale securities	0	0
Payment at Fair value | Level 2	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Due to Takeda, Fair value	$6,600,000	'
Maximum	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Maturity of highly liquid investments	'3 months	'

Collaborations_Additional_Info

Collaborations - Additional Information (Detail) (USD $)

0 Months Ended

1 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

9 Months Ended

1 Months Ended

0 Months Ended

Jul. 17, 2012

Jul. 31, 2010

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Feb. 24, 2014

Jul. 17, 2012

Nov. 30, 2008

Jul. 17, 2012

Sep. 30, 2014

Sep. 30, 2014

Jul. 29, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2012

Apr. 30, 2013

Apr. 30, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 02, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Feb. 28, 2014

Aug. 31, 2014

Jul. 17, 2012

Jul. 17, 2012

Product

Entity

Mundipharma and Purdue

Mundipharma and Purdue

Collaboration

Amended Agreement

Amended Agreement

Amended Agreement

Amended Agreement

BRP

BRP

License

License

Committee Services

Development Services

Development and Committee Services

Development and Committee Services

Maximum

Maximum

Maximum

Maximum

Maximum

Maximum

Minimum

Minimum

FAAH Program License

Line of Credit

Cash

Development Regulatory And Commercial Milestone

Clinical Development Milestone

Regulatory Filing and Approval Milestone

Commercial Milestone

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Research and development

'

'

$44,895,000

$26,857,000

$107,551,000

$73,168,000

'

'

'

'

'

$10,000,000

'

$5,000,000

'

'

'

'

'

'

'

'

'

'

$667,000,000

'

'

'

'

'

'

'

'

'

'

Upfront payment received

'

'

275,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

159,100,000

'

300,000

115,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Contingent milestone payments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

530,000,000

'

'

'

'

'

'

'

'

Potential milestones payments Under the terms of the AbbVie Agreement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

130,000,000

275,000,000

125,000,000

'

'

'

'

'

Agreed level of royalty depending on annual net sales

'

'

23.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Agreed level of royalty depending on annual net sales

'

'

30.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reduction of tiered royalty payments receivable, percentage

'

'

4.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaboration revenue

'

'

160,639,000

'

160,639,000

'

'

'

'

'

'

'

'

'

'

'

'

'

159,100,000

159,100,000

'

'

1,500,000

1,500,000

'

'

'

'

'

'

'

'

'

'

'

Collaboration revenue recognition period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'5 years

'

'

'

'

'

'

'

'

'

'

'

Deferred revenue

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

114,400,000

114,400,000

'

'

'

'

'

'

'

'

'

'

'

Up-front license fee

'

13,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Release payment

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Release payment, fair value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

14,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount paid on release payment during the period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6,700,000

1,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Development cost of distinct product candidates

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,000,000

'

'

'

'

'

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Option fee

'

'

'

'

'

'

'

'

'

'

'

'

5,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Exercise Fee

'

'

'

'

'

'

'

'

'

'

'

'

52,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ownership percentage received in exchange for licensed rights

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

23.00%

'

'

Gain (loss) recognized related to exchange of ownership percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

Strategic Alliance Agreement Termination date

'

'

'

'

'

'

'

'

'

'

'July 17, 2012

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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 1% 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

'

'

'

'

'

'

100,000,000

'

50,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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

'

'

'

'

'

'

'

'

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'

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'

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$27,500,000

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

'

'

'

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'

'

'

$14.50

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Number of entities

'

'

'

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2

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'

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'

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Number of shares of common stock sold

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11,416,565

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Number of shares of common stock sold, per share

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$40

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'

Debt_Facility_Agreement_Additi

Debt Facility Agreement - Additional Information (Detail) (USD $)	0 Months Ended		3 Months Ended	9 Months Ended
	Sep. 22, 2014	Feb. 24, 2014	Sep. 30, 2014	Sep. 30, 2014	Feb. 24, 2014	Dec. 31, 2013	Nov. 30, 2008
Debt Instrument [Line Items]	'	'	'	'	'	'	'
Line Of credit facility maximum borrowing capacity	'	'	'	'	$100,000,000	'	$50,000,000
Minimum draw down during the 12 months following effective date	50,000,000	25,000,000	'	'	'	'	'
Number of business days needed as prior notice for loan commitment	'	'22 days	'	'	'	'	'
Debt instrument, interest rate	'	'	'	'	7.95%	'	'
Debt instrument, final payment date	'	'	'	15-Dec-19	'	'	'
Percentage of fee to be paid on undrawn portion	'	'	'	3.00%	'	'	'
Facility fee	'	'	'	1,500,000	'	'	'
Total cash, cash equivalents and available-for-sale securities, Cost	'	'	379,404,000	379,404,000	'	214,312,000	'
Total cost of securing loan commitment	'	'	'	11,800,000	'	'	'
Fair value of the warrants issued	'	'	8,400,000	8,400,000	'	'	'
Common stock warrants issued	'	'	'	'	1,000,000	'	'
Transaction cost	'	'	'	400,000	'	'	'
Facility fee reduction rate	'	'	'	50.00%	'	'	'
Reduction rate in borrowing capacity	'	'	'	50.00%	'	'	'
Reduction rate in loan commitment asset outstanding	'	'	'	50.00%	'	'	'
Additional expense as a result of reduction in remaining loan commitment asset outstanding	'	'	1,800,000	'	'	'	'
Interest expense associated with amortization and write-off of the loan commitment asset	'	'	4,500,000	8,600,000	'	'	'
Common stock warrants issued, exercise price	'	'	'	'	$13.83	'	'
Additional warrants to purchase common stock, percentage	'	'	'	50.00%	'	'	'
Consecutive trading day period	'	'	'	'20 days	'	'	'
Number of common stock issuable upon exercise of Initial Warrants registered for resale	'	1,000,000	'	'	'	'	'
Number of days, on or before which, additional registration statements need to be filed with the SEC for resale of common stock issuable upon exercise of Draw Warrants	'	'30 days	'	'	'	'	'
Maximum	'	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'	'
Number of shares issuable under the agreement	'	'	9,500,000	9,500,000	'	'	'
Covenant Requirement | Minimum	'	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'	'
Total cash, cash equivalents and available-for-sale securities, Cost	'	'	$25,000,000	$25,000,000	'	'	'
Deerfield	'	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'	'
Principal amount of loan, percentage	'	'	'	100.00%	'	'	'
Ownership percentage	'	'	'	9.99%	'	'	'

Accrued_Expenses_Detail

Accrued Expenses (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Expenses [Line Items]	'	'
Accrued compensation and benefits	$7,041	$1,839
Accrued clinical studies	4,372	4,009
Accrued drug manufacturing costs	2,368	991
Accrued preclinical studies	432	303
Facility fee	1,500	'
Other	3,051	2,022
Total accrued expenses	$18,764	$9,164

Lease_Additional_Information_D

Lease - Additional Information (Detail) (USD $)	0 Months Ended	9 Months Ended
	Sep. 25, 2014	Sep. 30, 2014	Sep. 25, 2014
Leases Of Lessee Disclosure [Line Items]	'	'	'
Letters of credit, outstanding amount	'	$1,000,000	$1,000,000
Letters of credit, amendment amount	'	'	750,000
Payment made for repairs and updates	5,856,100	'	'
Rent free period	'	'5 months	'
Lease facility prepaid rent	'	170,291	'
Bank fee	'	30,000	'
Lease Agreements	'	'	'
Leases Of Lessee Disclosure [Line Items]	'	'	'
Area of premises leased under lease agreement	'	'	61,000
Lease commencement date	'	1-Nov-14	'
Lease expiration date	'	31-Mar-25	'
Lease term of contract	'10 years	'	'
Option to extend terms of the lease	'	2	'
Extended term of lease agreement	'	'5 years	'
Base rent for each extension term as a percentage of fair market base rent per square foot	'	95.00%	'
Lease Agreements | Maximum	'	'	'
Leases Of Lessee Disclosure [Line Items]	'	'	'
Lease notice period	'	'18 months	'
Lease Agreements | Minimum	'	'	'
Leases Of Lessee Disclosure [Line Items]	'	'	'
Lease notice period	'	'12 months	'
From the Commencement Date until April 1, 2015	'	'	'
Leases Of Lessee Disclosure [Line Items]	'	'	'
Facilities leases, base rent per month	0	'	0
From April 1, 2015 through March 31, 2020	'	'	'
Leases Of Lessee Disclosure [Line Items]	'	'	'
Facilities leases, base rent per month	170,291.67	'	170,291.67
From April 1, 2020 until the Expiration Date	'	'	'
Leases Of Lessee Disclosure [Line Items]	'	'	'
Facilities leases, base rent per month	$190,625	'	$190,625

Future_Minimum_Payments_Under_

Future Minimum Payments Under Facility Leases (Detail) (USD $)	Sep. 30, 2014
In Thousands, unless otherwise specified
Operating Leased Assets [Line Items]	'
2015	$1,362
2016	2,044
2017	2,044
2018	2,044
2019	2,044
2020 and beyond	11,947
Total minimum lease payments	$21,485

Subsequent_Event_Additional_In

Subsequent Event - Additional Information (Detail) (Subsequent Event, USD $)	0 Months Ended
	Nov. 06, 2014	Nov. 06, 2014
	Right	sqft
	sqft
Subsequent Event [Line Items]	'	'
Area of premises leased under lease agreement	54,861	54,861
790 Memorial Drive, or the 790 Premises	'	'
Subsequent Event [Line Items]	'	'
Area of premises leased under lease agreement	'	3,861
Land subject to ground leases	13,159	'
Lease expiration date	31-Mar-25	'
Number of options to extend terms of the lease	2	'
Extended term of lease agreement	'5 years	'
Lease arrangement description	'The Memorial Drive Lease provides that no base rent for the Premises shall be due (i) for the period commencing on February 1, 2015 through July 31, 2015, (ii) for the period commencing on February 1, 2016 through February 29, 2016, (iii) for the period commencing on February 1, 2017 through February 28, 2017, and (iv) for the period commencing on February 1, 2018 through February 28, 2018.	'
Receipt for design and construction of capital improvements	$1,097,220	'
Base allowance for the leased building per square foot	20	'
Tenant improvement allowance	1,920,135	'
Tenant improvement allowance per square foot	35	'
790 Memorial Drive, or the 790 Premises | February 1, 2016	'	'
Subsequent Event [Line Items]	'	'
Base rent per square foot	69	'
790 Memorial Drive, or the 790 Premises | February 1, 2018	'	'
Subsequent Event [Line Items]	'	'
Base rent per square foot	$70	'
790 Memorial Drive, or the 790 Premises | Previously Leased Area	'	'
Subsequent Event [Line Items]	'	'
Area of premises leased under lease agreement	17,020	17,020