Aveo Pharmaceuticals (AVEO) 10-K 13 Mar 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Feb. 28, 2014	Jun. 28, 2013
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Trading Symbol	'AVEO	'	'
Entity Registrant Name	'AVEO PHARMACEUTICALS INC	'	'
Entity Central Index Key	'0001325879	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Filer Category	'Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	51,793,605	'
Entity Public Float	'	'	$93,057,173

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$50,826	$76,134
Marketable securities	67,680	84,468
Accounts receivable	984	20,649
Tenant improvement allowance receivable	5,833	3,240
Restricted cash	598	'
Prepaid expenses and other current assets	2,998	6,190
Total current assets	128,919	190,681
Property and equipment, net	14,140	12,867
Other assets	290	321
Restricted cash	2,997	3,600
Total assets	146,346	207,469
Current liabilities:	'	'
Accounts payable	4,238	10,628
Accrued expenses	13,263	19,543
Loans payable, net of discount	10,383	6,809
Deferred revenue	1,294	1,294
Other liabilities	1,238	'
Deferred rent	992	856
Total current liabilities	31,408	39,130
Loans payable, net of current portion and discount	8,822	19,228
Deferred revenue, net of current portion	17,098	18,391
Deferred rent, net of current portion	19,080	10,544
Other liabilities	'	1,238
Commitments and contingencies (Note 8)	'	'
Stockholders' equity:	'	'
Preferred stock, $.001 par value: 5,000 shares authorized; no shares issued and outstanding	'	'
Common stock, $.001 par value: 100,000 shares authorized; 51,809 and 43,780 shares issued and outstanding at December 31, 2013 and 2012, respectively	52	44
Additional paid-in capital	497,177	439,173
Accumulated other comprehensive loss	-2	-19
Accumulated deficit	-427,289	-320,260
Total stockholders' equity	69,938	118,938
Total liabilities and stockholders' equity	$146,346	$207,469

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	'	'
Preferred stock, shares outstanding	'	'
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	51,809,028	43,779,560
Common stock, shares outstanding	51,809,028	43,779,560

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Collaboration revenue	$1,293	$19,286	$164,849
Operating expenses:	'	'	'
Research and development	68,468	91,358	101,735
General and administrative	28,712	36,932	29,167
Restructuring	8,017	2,633	'
Operating expenses	105,197	130,923	130,902
(Loss) income from operations	-103,904	-111,637	33,947
Other income and expense:	'	'	'
Other (expense) income, net	-123	247	10
Interest expense	-3,127	-3,501	-3,836
Interest income	125	497	527
Other expense, net	-3,125	-2,757	-3,299
Net (loss) income	($107,029)	($114,394)	$30,648
Basic net (loss) income per share:	'	'	'
Net (loss) income per share	($2.10)	($2.64)	$0.77
Weighted average number of common shares outstanding	50,928	43,374	39,715
Diluted net (loss) income per share:	'	'	'
Net (loss) income per share	($2.10)	($2.64)	$0.74
Weighted average number of common shares and dilutive common share equivalents outstanding	50,928	43,374	41,473

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive (Loss) Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net (loss) income	($107,029)	($114,394)	$30,648
Other comprehensive (loss) income:	'	'	'
Unrealized (losses) gains on available-for-sale securities	-9	174	-147
Foreign currency translation adjustment	26	-26	'
Comprehensive (loss) income	($107,012)	($114,246)	$30,501

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)

Total

follow-on stock offering

Licensing Agreements

Equity-classified awards

Liability Classified Awards

Common Shares

Common Shares

Common Shares

Common Shares

Additional Paid-in Capital

Additional Paid-in Capital

Additional Paid-in Capital

Additional Paid-in Capital

Additional Paid-in Capital

Accumulated Other Comprehensive Loss

Accumulated Deficit

In Thousands, except Share data

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

follow-on stock offering

Licensing Agreements

Liability Classified Awards

USD ($)

follow-on stock offering

Licensing Agreements

Equity-classified awards

Liability Classified Awards

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Beginning Balance at Dec. 31, 2010

$71,770

'

'

'

'

$36

'

'

'

$308,268

'

'

'

'

($20)

($236,514)

Beginning Balance (in shares) at Dec. 31, 2010

'

'

'

'

'

35,604,000

'

'

'

'

'

'

'

'

'

'

Exercise of stock options (in shares)

'

'

'

'

'

565,000

'

'

'

'

'

'

'

'

'

'

Exercise of stock options

2,458

'

'

'

'

1

'

'

'

2,457

'

'

'

'

'

'

Exercise of warrants

'

'

'

'

'

168,000

'

'

'

'

'

'

'

'

'

'

Stock-based compensation expense

5,903

'

'

'

'

'

'

'

'

5,903

'

'

'

'

'

'

Issuance of common stock under employee stock purchase plan (in shares)

'

'

'

'

'

58,000

'

'

'

'

'

'

'

'

'

'

Issuance of common stock under employee stock purchase plan

779

'

'

'

'

'

'

'

'

779

'

'

'

'

'

'

Issuance of common stock (in shares)

'

'

'

'

'

'

6,352,000

438,000

'

'

'

'

'

'

'

'

Issuance of common stock

'

104,208

7,922

'

'

'

6

'

'

'

104,202

7,922

'

'

'

'

Issuance of restricted stock awards, net of forfeitures

'

'

'

'

'

69,000

'

'

'

'

'

'

'

'

'

'

Change in unrealized gain/loss on investments

-147

'

'

'

'

'

'

'

'

'

'

'

'

'

-147

'

Net income

30,648

'

'

'

'

'

'

'

'

'

'

'

'

'

'

30,648

Ending Balance at Dec. 31, 2011

223,541

'

'

'

'

43

'

'

'

429,531

'

'

'

'

-167

-205,866

Ending Balance (in shares) at Dec. 31, 2011

'

'

'

'

'

43,254,000

'

'

'

'

'

'

'

'

'

'

Exercise of stock options (in shares)

'

'

'

'

'

220,000

'

'

'

'

'

'

'

'

'

'

Exercise of stock options

826

'

'

'

'

1

'

'

'

825

'

'

'

'

'

'

Stock-based compensation expense

'

'

'

8,007

'

'

'

'

'

'

'

'

8,007

'

'

'

Issuance of common stock under employee stock purchase plan (in shares)

'

'

'

'

'

95,000

'

'

'

'

'

'

'

'

'

'

Issuance of common stock under employee stock purchase plan

810

'

'

'

'

'

'

'

'

810

'

'

'

'

'

'

Issuance of restricted stock awards, net of forfeitures

'

'

'

'

'

211,000

'

'

'

'

'

'

'

'

'

'

Change in unrealized gain/loss on investments

174

'

'

'

'

'

'

'

'

'

'

'

'

'

174

'

Cumulative translation adjustment

-26

'

'

'

'

'

'

'

'

'

'

'

'

'

-26

'

Net income

-114,394

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-114,394

Ending Balance at Dec. 31, 2012

118,938

'

'

'

'

44

'

'

'

439,173

'

'

'

'

-19

-320,260

Ending Balance (in shares) at Dec. 31, 2012

'

'

'

'

'

43,780,000

'

'

'

'

'

'

'

'

'

'

Exercise of stock options (in shares)

185,311

'

'

'

'

185,000

'

'

'

'

'

'

'

'

'

'

Exercise of stock options

272

'

'

'

'

1

'

'

'

271

'

'

'

'

'

'

Issuance of common stock to settle liability-classified share awards granted to directors (in shares)

'

'

'

'

'

'

'

'

39,000

'

'

'

'

'

'

'

Issuance of common stock to settle liability-classified share awards granted to directors

'

'

'

'

119

'

'

'

'

'

'

'

'

119

'

'

Stock-based compensation expense

'

'

'

3,791

'

'

'

'

'

'

'

'

3,791

'

'

'

Issuance of common stock under employee stock purchase plan (in shares)

'

'

'

'

'

110,000

'

'

'

'

'

'

'

'

'

'

Issuance of common stock under employee stock purchase plan

193

'

'

'

'

'

'

'

'

193

'

'

'

'

'

'

Issuance of common stock (in shares)

'

'

'

'

'

'

7,667,000

'

'

'

'

'

'

'

'

'

Issuance of common stock

'

53,637

'

'

'

'

7

'

'

'

53,630

'

'

'

'

'

Issuance of restricted stock awards, net of forfeitures

'

'

'

'

'

28,000

'

'

'

'

'

'

'

'

'

'

Change in unrealized gain/loss on investments

-9

'

'

'

'

'

'

'

'

'

'

'

'

'

-9

'

Cumulative translation adjustment

26

'

'

'

'

'

'

'

'

'

'

'

'

'

26

'

Net income

-107,029

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-107,029

Ending Balance at Dec. 31, 2013

$69,938

'

'

'

'

$52

'

'

'

$497,177

'

'

'

'

($2)

($427,289)

Ending Balance (in shares) at Dec. 31, 2013

'

'

'

'

'

51,809,000

'

'

'

'

'

'

'

'

'

'

Consolidated_Statements_of_Sto1

Consolidated Statements of Stockholders' Equity (Parenthetical) (Additional Paid-in Capital, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2011
follow-on stock offering	'	'
Issuance of common stock, issuance costs	$3,865	$6,960
Licensing Agreements	'	'
Issuance of common stock, issuance costs	'	$113

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities	'	'	'
Net (loss) income	($107,029)	($114,394)	$30,648
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:	'	'	'
Depreciation and amortization	3,775	2,510	1,654
Net loss on disposal of property and equipment	83	42	35
Impairment of property and equipment	65	'	'
Stock-based compensation	3,940	8,007	5,903
Non-cash interest expense	285	380	788
Amortization of premiums and discounts on investments	1,041	2,446	3,801
Changes in operating assets and liabilities:	'	'	'
Accounts receivable	19,665	-13,439	-6,819
Tenant improvement allowance receivable	-2,593	-3,180	-60
Prepaid expenses and other current assets	3,179	-207	-1,153
Other noncurrent assets	31	-200	335
Restricted cash	5	-2,849	-144
Accounts payable	-6,390	1,724	-343
Accrued expenses	-7,838	5,254	4,168
Deferred revenue	-1,293	-1,293	-12,224
Other liabilities	'	-1,249	'
Deferred rent	8,672	10,719	-138
Net cash (used in) provided by operating activities	-84,402	-105,729	26,451
Investing activities	'	'	'
Purchases of property and equipment	-3,668	-9,948	-2,628
Purchases of marketable securities	-175,391	-194,584	-376,270
Proceeds from maturities and sales of marketable securities	191,129	339,779	234,795
Net cash provided by (used in) investing activities	12,070	135,247	-144,103
Financing activities	'	'	'
Proceeds from issuance of common stock, net of issuance costs	53,637	'	112,130
Proceeds from issuance of stock for stock-based compensation arrangements	465	1,636	3,237
Proceeds from refinancing of loans payable	'	3,672	'
Principal payments on loans payable	-7,104	-2,172	'
Net cash provided by financing activities	46,998	3,136	115,367
Net (decrease) increase in cash and cash equivalents	-25,334	32,654	-2,285
Effect of exchange rate changes on cash and cash equivalents	26	-26	'
Cash and cash equivalents at beginning of period	76,134	43,506	45,791
Cash and cash equivalents at end of period	50,826	76,134	43,506
Supplemental cash flow and noncash investing and financing activities	'	'	'
Cash paid for interest	$2,916	$3,104	$3,016

Nature_of_Business_and_Organiz

Nature of Business and Organization	12 Months Ended
	Dec. 31, 2013
Nature of Business and Organization	'
	1	Nature of Business and Organization
	AVEO Pharmaceuticals, Inc. (the “Company”) is a biopharmaceutical company committed to discovering and developing targeted therapies designed to provide substantial impact in the lives of people with cancer by addressing unmet medical needs. The Company’s product candidates are directed against important mechanisms, or targets, known or believed to be involved in cancer. The Company’s proprietary Human Response Platform™ provides the Company with unique insights into cancer biology and is leveraged in the discovery and clinical development of therapeutics.
	The Company has a pipeline of monoclonal antibodies, including ficlatuzumab, a product candidate for which the Company has completed a phase 2 clinical study, and AV-203, a clinical stage monoclonal antibody that targets the ERBB3 (HER3) receptor, which the Company has partnered with Biogen Idec, Inc.
	The Company and its partner Astellas Pharma, Inc. (“Astellas”) have been developing tivozanib for the treatment of various types of cancers such as renal cell carcinoma, colorectal cancer and breast cancer. As further described in Footnote 16, Astellas notified the Company in February 2014 that it has elected to terminate the worldwide collaboration and license agreement. This termination will become effective in August 2014, at which time the tivozanib rights will be returned to the Company.
	In 2012, the Company initiated a program focusing on cachexia, a serious and common complication of advanced cancer and a number of chronic diseases that is characterized by symptoms of unintentional weight loss, progressive muscle wasting, and a loss of appetite. The program’s primary research focus is in the area of cancer cachexia, where there is a major unmet need. AV-380, the Company’s lead drug candidate, is a potent humanized IgG1 inhibitory monoclonal antibody targeting growth differentiating factor-15, or GDF-15, a divergent member of the TGF-b. family.
	As used throughout these consolidated financial statements, the terms “AVEO,” and “the Company” refer to the business of AVEO Pharmaceuticals, Inc. and its subsidiaries, AVEO Pharma Limited and AVEO Securities Corporation, both of which are wholly-owned.
	The Company has an accumulated deficit as of December 31, 2013 of approximately $427.3 million, and will require substantial additional capital for research and product development. The Company believes that its existing cash, cash equivalents, and marketable securities are sufficient to fund its operations through at least the next twelve months.

Significant_Accounting_Policie

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Significant Accounting Policies	'
	2	Significant Accounting Policies
	Revenue Recognition
	The Company’s revenues are generated primarily through collaborative research, development and commercialization agreements. The terms of these agreements generally contain multiple elements, or deliverables, which may include (i) licenses, or options to obtain licenses, to the Company’s technology, (ii) research and development activities to be performed on behalf of the collaborative partner, and (iii) in certain cases, services in connection with the manufacturing of pre-clinical and clinical material. Payments to the Company under these arrangements typically include one or more of the following: non-refundable, up-front license fees; option exercise fees; funding of research and/or development efforts; milestone payments; and royalties on future product sales.
	When evaluating multiple element arrangements, the Company considers whether the deliverables under the arrangement represent separate units of accounting. This evaluation requires subjective determinations and requires management to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. In determining the units of accounting, management evaluates certain criteria, including whether the deliverables have standalone value, based on the relevant facts and circumstances for each arrangement. The consideration received is allocated among the separate units of accounting using the relative selling price method, and the applicable revenue recognition criteria are applied to each of the separate units.
	The Company determines the estimated selling price for deliverables within each agreement using vendor-specific objective evidence (“VSOE”) of selling price, if available, third-party evidence (“TPE”) of selling price if VSOE is not available, or best estimate of selling price if neither VSOE nor TPE is available. Determining the best estimate of selling price for a deliverable requires significant judgment. The Company typically uses best estimate of selling price to estimate the selling price for licenses to the Company’s proprietary technology, since the Company often does not have VSOE or TPE of selling price for these deliverables. In those circumstances where the Company utilizes best estimate of selling price to determine the estimated selling price of a license to the Company’s proprietary technology, the Company considers market conditions as well as entity-specific factors, including those factors contemplated in negotiating the agreements and internally developed models that include assumptions related to the market opportunity, estimated development costs, probability of success and the time needed to commercialize a product candidate pursuant to the license. In validating the Company’s best estimate of selling price, the Company evaluates whether changes in the key assumptions used to determine the best estimate of selling price will have a significant effect on the allocation of arrangement consideration among multiple deliverables.
	The Company typically receives non-refundable, up-front payments when licensing its intellectual property in conjunction with a research and development agreement. When management believes the license to its intellectual property does not have stand-alone value from the other deliverables to be provided in the arrangement, the Company generally recognizes revenue attributed to the license on a straight-line basis over the Company’s contractual or estimated performance period, which is typically the term of the Company’s research and development obligations. If management cannot reasonably estimate when the Company’s performance obligation ends, then revenue is deferred until management can reasonably estimate when the performance obligation ends. When management believes the license to its intellectual property has stand-alone value, the Company generally recognizes revenue attributed to the license upon delivery. The periods over which revenue should be recognized are subject to estimates by management and may change over the course of the research and development agreement. Such a change could have a material impact on the amount of revenue the Company records in future periods.
	Payments or reimbursements resulting from the Company’s research and development efforts for those arrangements where such efforts are considered as deliverables are recognized as the services are performed and are presented on a gross basis so long as there is persuasive evidence of an arrangement, the fee is fixed or determinable, and collection of the related receivable is reasonably assured. Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying balance sheets.
	At the inception of each agreement that includes milestone payments, the Company evaluates whether each milestone is substantive and at risk to both parties on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether (a) the consideration is commensurate with either (1) the entity’s 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 the entity’s performance to achieve the milestone, (b) the consideration relates solely to past performance, and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required to achieve the respective milestone and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment.
	The Company aggregates its milestones into four categories: (i) clinical and development milestones, (ii) regulatory milestones, (iii) commercial milestones, and (iv) patent-related milestones. Clinical and development milestones are typically achieved when a product candidate advances into a defined phase of clinical research or completes such phase. For example, a milestone payment may be due to the Company upon the initiation of a phase 3 clinical trial for a new indication, which is the last phase of clinical development and could eventually contribute to marketing approval by the U.S. Food and Drug Administration (“FDA”) or other global regulatory authorities. Regulatory milestones are typically achieved upon acceptance of the submission for marketing approval of a product candidate or upon approval to market the product candidate by the FDA or other global regulatory authorities. For example, a milestone payment may be due to the Company upon the FDA’s acceptance of a New Drug Application (“NDA”). Commercial milestones are typically achieved when an approved pharmaceutical product reaches certain defined levels of net sales by the licensee, such as when a product first achieves global sales or annual sales of a specified amount. Patent-related milestones are typically achieved when a patent application is filed or a patent is issued with respect to certain intellectual property related to the applicable collaboration.
	Revenues from clinical and development, regulatory, and patent-related milestone payments, if the milestones are deemed substantive and the milestone payments are nonrefundable, are recognized upon successful accomplishment of the milestones. The Company has concluded that the clinical and development, regulatory and patent-related milestones pursuant to its current research and development arrangements are substantive. Milestones that are not considered substantive are accounted for as license payments and recognized on a straight-line basis over the remaining period of performance. Revenues from commercial milestone payments are accounted for as royalties and are recorded as revenue upon achievement of the milestone, assuming all other revenue recognition criteria are met.
	Principles of Consolidation
	The Company’s consolidated financial statements include the Company’s accounts and the accounts of the Company’s wholly-owned subsidiaries, AVEO Pharma Limited and AVEO Securities Corporation. All intercompany transactions have been eliminated.
	Research and Development Expenses
	Research and development expenses are charged to expense as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including personnel-related costs such as salaries and stock-based compensation, facilities, research-related overhead, clinical trial costs, manufacturing costs and costs of other contracted services, license fees, and other external costs. Nonrefundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received.
	Cash and Cash Equivalents
	The Company considers highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash and cash equivalents at December 31, 2013 consisted of money market funds, asset-backed securities, asset-backed commercial paper, and corporate debt securities, including commercial paper, maintained by an investment manager. Cash and cash equivalents at December 31, 2012 consisted of a money market fund and corporate debt securities, including commercial paper, maintained by an investment manager.
	Marketable Securities
	Marketable securities at December 31, 2013 consisted of U.S. government agency securities, asset-backed securities, and corporate debt securities, including commercial paper, maintained by an investment manager. Marketable securities at December 31, 2012 consisted of municipal bonds, asset-backed commercial paper, asset-backed securities, and corporate debt securities, including commercial paper, maintained by an investment manager. Credit risk is reduced as a result of the Company’s policy to limit the amount invested in any one issue. Marketable securities consist primarily of investments which have expected average maturity dates in excess of three months, but not longer than 24 months. The Company classifies these investments as available-for-sale. Unrealized gains and losses are included in other comprehensive (loss) income until realized. The cost of securities sold is based on the specific identification method. The Company sold three securities during the year ended December 31, 2013 for gross proceeds of $10.3 million and did not recognize any gain or loss on the transactions. The Company sold one security during the year ended December 31, 2012 for gross proceeds of $2.7 million and recognized an immaterial gain. No securities were sold during the year ended December 31, 2011.
	Available-for-sale securities at December 31, 2013 and December 31, 2012 consist of the following:
			Amortized		Unrealized			Unrealized			Fair
			Cost		Gains			Losses			Value
			(in thousands)
	December 31, 2013:
	Corporate debt securities (Due within 1 year)		$	52,156	$	4		$	(4	)	$	52,156
	Government agency securities (Due within 1 year)			7,519		—			—			7,519
	Asset-backed securities (Due within 1 year)			8,007		—			(2	)		8,005
			$	67,682	$	4		$	(6	)	$	67,680
	December 31, 2012:
	Corporate debt securities (Due within 1 year)		$	58,751	$	16		$	(11	)	$	58,756
	Municipal bonds (Due within 1 year)			10,545		—			—			10,545
	Asset-backed securities (Due within 1 year)			6,359		—			—			6,359
	Asset-backed commercial paper (Due within 1 year)			8,806		2			—			8,808
			$	84,461	$	18		$	(11	)	$	84,468
	The aggregate fair value of securities in an unrealized loss position for less than 12 months at December 31, 2013 was $45.6 million, representing 18 securities. There were no securities that were in an unrealized loss position for greater than 12 months at December 31, 2013. The unrealized loss was caused by a temporary change in the market for those securities primarily caused by changes in market interest rates. There was no change in the credit risk of the securities. To determine whether an other-than-temporary impairment exists, the Company performs an analysis to assess whether it intends to sell, or whether it would more likely than not be required to sell, the security before the expected recovery of the amortized cost basis of the security. Where the Company intends to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary and the full amount of the unrealized loss is recorded in the statement of operations as an other-than-temporary impairment charge. When this is not the case, the Company performs additional analyses on all securities with unrealized losses to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where the Company does not expect to receive cash flows, based on using a single best estimate, sufficient to recover the amortized cost basis of a security and these recognized in other (expense) income, net. The Company does not believe an other-than-temporary impairment exists with respect to those securities in an unrealized loss position at December 31, 2013.
	Marketable securities in an unrealized loss position at December 31, 2013 and 2012 consist of the following:
			Aggregate		Unrealized
			Fair Value		Losses
			(in thousands)
	December 31, 2013:
	Corporate debt securities (Due within 1 year)		$	30,106	$	(4	)
	Government agency securities (Due within 1 year)			7,519		—
	Asset-backed securities (Due within 1 year)			8,005		(2	)
			$	45,630	$	(6	)
	December 31, 2012:
	Corporate debt securities (Due within 1 year)		$	29,806	$	(11	)
	Asset-backed securities (Due within 1 year)			6,359		—
			$	36,165	$	(11	)
	Concentrations of Credit Risk
	Financial instruments that potentially subject the Company to credit risk primarily consist of cash, cash equivalents and marketable securities. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits.
	Management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held.
	The Company’s credit risk related to marketable securities is reduced as a result of the Company’s policy to limit the amount invested in any one issue.
	Fair Value Measurements
	The Company records cash equivalents and marketable securities at fair value. The accounting standards for fair value measurements establish a hierarchy that distinguishes between fair value measurements based on market data (observable inputs) and those based on the Company’s own assumptions (unobservable inputs). The hierarchy consists of three levels:
		•		Level 1—Quoted market prices in active markets for identical assets or liabilities. Assets that are valued utilizing only Level 1 inputs include money market funds.
		•		Level 2—Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. Assets that are valued utilizing Level 2 inputs include U.S. government agency securities, asset-backed securities, and corporate bonds, including commercial paper. These investments have been initially valued at the transaction price and are subsequently valued, at the end of each reporting period, utilizing third party pricing services or other observable market data. The pricing services utilize industry standard valuation models, including both income and market based approaches and observable market inputs to determine value. These observable market inputs include reportable trades, benchmark yields, credit spreads, broker/dealer quotes, bids, offers, current spot rates, and other industry and economic events. The Company validates the prices provided by third party pricing services by reviewing their pricing methods and matrices, obtaining market values from other pricing sources, analyzing pricing data in certain instances and confirming that the relevant markets are active. After completing its validation procedures, the Company did not adjust or override any fair value measurements provided by pricing services as of December 31, 2013 or December 31, 2012.
		•		Level 3—Unobservable inputs developed using estimates and assumptions developed by the Company, which reflect those that a market participant would use. The Company currently has no assets or liabilities recorded at fair value that utilize Level 3 inputs.
	The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis in the accompanying consolidated balance sheets as of December 31, 2013 and 2012.
			Fair Value Measurements of Cash Equivalents and
			Marketable Securities as of December 31, 2013
			Level 1		Level 2			Level 3			Total
			(in thousands)
	Cash equivalents		$	29,865	$	15,958		$	—		$	45,823
	Marketable securities			—		67,680			—			67,680
		$	29,865	$	83,638		$	—		$	113,503
		Fair Value Measurements of Cash Equivalents and
		Marketable Securities as of December 31, 2012
		Level 1		Level 2			Level 3			Total
		(in thousands)
Cash equivalents		$	51,182	$	18,121		$	—		$	69,303
Marketable securities			—		84,468			—			84,468
		$	51,182	$	102,589		$	—		$	153,771
The fair value of the Company’s loans payable at December 31, 2013 and 2012, computed pursuant to a discounted cash flow technique using the effective interest rate under the loan, was $20.1 million and $26.4 million, respectively. These fair values are considered a level 2 fair value measurement. The effective interest rate considers the fair value of the warrant issued in connection with the loan, loan issuance costs and a deferred charge, which approximates a market interest rate. The fair value of the Company’s term loan payable is determined using current applicable rates for similar instruments as of the balance sheet date.
Property and Equipment
Property and equipment are stated at cost and are depreciated using the straight-line method over the estimated useful lives of the respective assets. Maintenance and repair costs are charged to expense as incurred.
Long-lived Assets
The Company reviews long-lived assets, including property and equipment, for impairment whenever changes in business circumstances indicate that the carrying amount of the asset may not be fully recoverable. During the year ended December 31, 2013, the Company recognized $0.1 million of impairment losses. No impairment losses were recognized during the years ended December 31, 2012 or 2011.
Stock-Based Compensation
Under the Company’s stock-based compensation programs, the Company periodically grants stock options and restricted stock to employees, directors and nonemployee consultants. The Company also issues shares under an employee stock purchase plan. The fair value of all awards is recognized in the Company’s statements of operations over the requisite service period for each award. Awards that vest as the recipient provides service are expensed on a straight-line basis over the requisite service period. Other awards, such as performance-based awards that vest upon the achievement of specified goals, are expensed using the accelerated attribution method if achievement of the specified goals is considered probable.
The fair value of equity-classified awards to employees and directors are measured on the date the awards are granted. During the years ended December 31, 2013, 2012 and 2011, the Company recorded the following stock-based compensation expense for equity-classified awards:
		Years Ended December 31,
		2013		2012			2011
		(in thousands)
Research and development		$	1,991	$	3,566		$	2,504
General and administrative			1,800		4,380			3,399
Restructuring			—		61			—
Total stock-based compensation expense		$	3,791	$	8,007		$	5,903
Liability-classified awards to employees and directors are re-measured to the award’s fair value as of each balance sheet date until the award is settled. The Company recorded $0.1 million in compensation expense for liability-classified awards during the year ending December 31, 2013. No costs associated with liability-classified awards were recognized during the years ended December 31, 2012 or 2011.
Awards to nonemployee consultants are recorded at their fair values and re-measured to the award’s fair value as of each balance sheet date until the recipient’s services are complete.
Stock-based compensation expense is allocated to research and development and general and administrative expense based upon the department of the employee to whom each award was granted. No related tax benefits of the stock-based compensation expense have been recognized.
Income Taxes
The Company provides for income taxes using the asset-liability method. Under this method, deferred tax assets and liabilities are recognized based on differences between financial reporting and tax bases of assets and liabilities, and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Uncertain tax positions are recognized if the position is more-likely-than-not to be sustained upon examination by a tax authority. Unrecognized tax benefits represent tax positions for which reserves have been established.
Segment and Geographic Information
Operating segments are defined as components of an enterprise engaging in business activities for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment principally in the United States. The Company has $1.0 million of net assets located in the United Kingdom.
Use of Estimates
The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires the Company’s management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Reclassifications
The Company has reclassified the tenant improvement allowance receivable from prepaid expenses and other current assets on the consolidated balance sheets to a separate financial statement line to conform to the current period presentation.

Loss_Earnings_Per_Common_Share

(Loss) Earnings Per Common Share	12 Months Ended
	Dec. 31, 2013
(Loss) Earnings Per Common Share	'
	3	(Loss) Earnings Per Common Share
	Basic (loss) earnings per share is computed by dividing net (loss) income available to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed by dividing net income available to common stockholders by the weighted-average number of common shares and dilutive common share equivalents then outstanding. Potential common share equivalents consist of restricted stock awards and the incremental common shares issuable upon the exercise of stock options and warrants. Under the treasury stock method, unexercised “in-the-money” stock options are assumed to be exercised at the beginning of the period or at issuance, if later. The assumed proceeds are then used to purchase common shares at the average market price during the period. Stock-based payment awards that entitle their holders to receive non-forfeitable dividends before vesting are considered participating securities and are included in the calculation of basic and diluted earnings per share. Common share equivalents have not been included in the net loss per share computation for the years ended December 31, 2013 and 2012 because their effect is anti-dilutive.
	Basic and diluted (loss) earnings per share for the years ended December 31, 2013, 2012 and 2011 are as follows:
			Years Ended December 31,
			2013			2012			2011
			(in thousands, except per share amounts)
	Basic (loss) earnings per share
	Net (loss) income		$	(107,029	)	$	(114,394	)	$	30,648
	Income allocated to participating securities			—			—			(46	)
	(Loss) income available to common stockholders			(107,029	)		(114,394	)		30,602
	Basic weighted average common shares outstanding			50,928			43,374			39,715
	Basic (loss) earnings per share		$	(2.10	)	$	(2.64	)	$	0.77
	Diluted (loss) earnings per share
	Net (loss) income		$	(107,029	)	$	(114,394	)	$	30,648
	Income allocated to participating securities			—			—			(45	)
	(Loss) income available to common stockholders			(107,029	)		(114,394	)		30,603
	Weighted average common shares outstanding			50,928			43,374			39,715
	Diluted potential common shares			—			—			1,758
	Diluted weighted average common shares and potential common shares			50,928			43,374			41,473
	Diluted (loss) earnings per share		$	(2.10	)	$	(2.64	)	$	0.74
	The following potentially dilutive securities were excluded from the calculation of diluted net (loss) earnings per share due to their anti-dilutive effect:
			Years Ended December 31,
			2013			2012			2011
			(in thousands)
	Outstanding stock options			4,297			4,638			276
	Unvested restricted stock			242			245			—

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2013
Property and Equipment	'
	4	Property and Equipment
	Property and equipment consists of the following:
			Estimated	December 31,			December 31,
			Useful Life	2013			2012
				(in thousands)
	Laboratory equipment		5 years	$	8,660		$	9,299
	Computer equipment and software		3 years		4,398			3,480
	Office furniture		5 years		930			579
	Leasehold improvements		Shorter of asset’s useful life		11,959			5,090
			or remaining term of lease
	Construction in process		—		3,193			6,956
					29,140			25,404
	Less accumulated depreciation and amortization				(15,000	)		(12,537	)
	Property and equipment, net			$	14,140		$	12,867
	Depreciation expense for the years ended December 31, 2013, 2012 and 2011 was $3.8 million, $2.5 million and $1.7 million, respectively.

Accrued_Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2013
Accrued Expenses	'
	5	Accrued Expenses
	Accrued expenses consisted of the following:
			December 31,		December 31,
			2013		2012
			(in thousands)
	Clinical expenses		$	5,319	$	6,688
	Salaries and benefits			2,027		6,015
	Property and equipment			1,905		377
	Manufacturing and distribution			1,362		670
	Professional fees			811		430
	Restructuring			587		1,653
	Collaboration expenses			—		1,807
	Pre-commercialization expenses			—		924
	Other			1,252		979
			$	13,263	$	19,543

Loans_Payable

Loans Payable	12 Months Ended
	Dec. 31, 2013
Loans Payable	'
	6	Loans Payable
	In May 2010, the Company entered into a loan and security agreement (the “Loan Agreement”) with Hercules Technology II, L.P. and Hercules Technology III, L.P., affiliates of Hercules Technology Growth (collectively, “Hercules”), pursuant to which the Company received a loan in the aggregate principal amount of $25.0 million. The Company was initially required to repay the aggregate principal balance under the Loan Agreement in 30 equal monthly installments of principal starting on April 1, 2011; however, the Loan Agreement provided that such date would be extended under certain circumstances. During 2011, the Company triggered two possible extensions to the date from which principal payments were to be made and, as a result, the initial date for principal repayment was extended to January 1, 2012. On March 31, 2012, the Company entered into an amendment to the Loan Agreement, pursuant to which the Company increased the principal amount under the Loan Agreement to $26.5 million. Under the amendment to the Loan Agreement, the date on which the Company was required to begin repaying the aggregate principal balance was extended to March 31, 2013, at which point the Company began to repay such balance in 30 equal monthly installments. The Company accounted for this amendment as a loan modification.
	Per annum interest on the principal balance of the loan is payable at the greater of 11.9% and an amount equal to 11.9% plus the prime rate of interest minus 4.75%, provided however, that the per annum interest shall not exceed 15.0%. The Company must make interest payments on the loan each month following the date of borrowing under the Loan Agreement. The unpaid principal balance and all accrued but unpaid interest will be due and payable on September 1, 2015. The loan is secured by a lien on all of the Company’s personal property as of, or acquired after, the date of the Loan Agreement, except for intellectual property.
	The Loan Agreement required a deferred charge of $1.25 million which was paid in May 2012 related to the amendment of the Loan Agreement. The Loan Agreement also includes an additional deferred charge of $1.24 million due in June 2014 which has been recorded as a loan discount and is being amortized to interest expense over the term of the Loan Agreement using the effective interest rate method. The Company recorded a liability for the full amount of the charge since the payment of such amount is not contingent on any future event. The Company incurred approximately $0.2 million in loan issuance costs paid directly to the lenders related to the Loan Agreement, which were offset against the loan proceeds and are accounted for as a loan discount. As part of the Loan Agreement, the Company issued warrants to the lenders on June 2, 2010 to purchase up to 156,641 shares of the Company’s common stock at an exercise price equal to $7.98 per share. The Company recorded the relative fair value of the warrants of approximately $0.8 million as stockholders’ equity and as a discount to the related loan outstanding and is amortizing the value of the discount to interest expense over the term of the loan using the effective interest method. The relative fair value of the warrants was calculated using the Black-Scholes option-pricing model with the following assumptions: volatility of 64.12%, an expected term equal to the contractual life of the warrant (seven years), a risk-free interest rate of 2.81% and no dividend yield. The resulting effective interest rate for the loans outstanding under the Loan Agreement is approximately 13.1%.
	Hercules also received an option, subject to the Company’s written consent, not to be unreasonably withheld, to purchase, either with cash or through conversion of outstanding principal under the loan, up to $2.0 million of equity of the Company sold in any sale by the Company to third parties of equity securities resulting in at least $10.0 million in net cash proceeds to the Company, subject to certain exceptions. The Company has evaluated the embedded conversion option, and has concluded that it does not need to be bifurcated and separately accounted for. No amount will be recognized for the conversion feature until such time as the conversion feature is exercised and it can be determined whether a beneficial conversion feature exists. As of December 31, 2013, the principal balance outstanding was $19.4 million.
	The Loan Agreement defines events of default, including the occurrence of an event that results in a material adverse effect upon the Company’s business operations, properties, assets or condition (financial or otherwise), its ability to perform its obligations under and in accordance with the terms of the Loan Agreement, or upon the ability of the lenders to enforce any of their rights or remedies with respect to such obligations, or upon the collateral under the Loan Agreement, the related liens or the priority thereof. As of December 31, 2013, the lenders have not asserted any events of default under the loan. While the Company does not believe that there has been a material adverse change, as defined in the Loan Agreement, it is possible that Hercules could take the position that the adverse outcome relating to the development and commercialization of tivozanib for RCC, including the FDA informing the Company that it would not approve the NDA for tivozanib for the treatment of patients with advanced RCC, the related shareholder litigation described below in Footnote 15—Legal Actions, and Astellas’ decision to terminate its collaboration with the Company, collectively constitutes a material adverse change, and, accordingly, an event of default, which could trigger a repayment of all principal and interest due under the loan unless such event of default is waived by Hercules. The Company has classified the principal amount of the loan as current and non-current on its consolidated balance sheet based upon the expected timing of the remaining payments.
	Future minimum payments under the loans payable outstanding as of December 31, 2013 are as follows (amounts in thousands):
	Years Ending December 31:
	2014			13,547
	2015			9,309
				22,856
	Less amount representing interest			(2,221	)
	Less discount			(192	)
	Less deferred charges			(1,238	)
	Less current portion			(10,383	)
	Loans payable, net of current portion		$	8,822

Collaboration_and_License_Agre

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2013
Collaboration and License Agreements	'
	7	Collaboration and License Agreements
	(a) Out-License Agreements
	Astellas Pharma Inc.
	In February 2011, the Company, together with its wholly-owned subsidiary AVEO Pharma Limited, entered into a Collaboration and License Agreement with Astellas (the “Astellas Agreement”), pursuant to which the Company and Astellas intended to develop and commercialize tivozanib for the treatment of a broad range of cancers. Under the terms of the Astellas Agreement, the Company and Astellas share responsibility for continued development and commercialization of tivozanib in North America and in Europe under a joint development plan and a joint commercialization plan, respectively. Throughout the rest of the world (the “Royalty Territory”), excluding Asia, where Kyowa Hakko Kirin (“KHK”) has retained all development and commercialization rights, Astellas has an exclusive, royalty-bearing license to develop and commercialize tivozanib. The terms of the Astellas Agreement are subject to the Company’s obligations to KHK under a license agreement entered into with KHK in 2006 pursuant to which the Company acquired exclusive rights to develop and commercialize tivozanib worldwide outside of Asia.
	Per the Astellas Agreement, Astellas has the right to terminate the Astellas Agreement, in its entirety or solely with respect to the Royalty Territory, at any time upon 180 days prior written notice to the Company. Either party may terminate the Astellas Agreement with respect to a specified territory or country as set forth in the Astellas Agreement, if the other party fails to cure a material breach related to such territory or country, as applicable. The Company may also terminate the Astellas Agreement in its entirety upon a patent-related challenge by Astellas, its affiliates or sublicensees if such patent-related challenge is not withdrawn within 30 days following the Company’s notice to Astellas of such termination. There are no refund provisions in the Astellas Agreement.
	In June 2013, the Company received a complete response letter from the FDA informing the Company that the FDA will not approve in its present form the Company’s NDA for tivozanib for the treatment of patients with advanced RCC. As further noted in Footnote 16, AVEO and Astellas jointly decided in January 2014 to discontinue a Phase 2 breast cancer clinical trial due to insufficient enrollment. Further, Astellas elected in February 2014 to terminate the collaboration as a result of the limited scope of development for tivozanib moving forward after terminating a Phase 2 study in patients with colorectal cancer. This termination will be effective August 2014, at which time the tivozanib rights will be returned to the Company. In accordance with the collaboration and license agreement, committed development costs, including the costs of winding down discontinued tivozanib clinical development programs, will be shared equally.
	Under the Astellas Agreement, the Company received an initial cash payment of $125.0 million, comprised of a $75.0 million license fee and $50.0 million in research and development funding. The Company retained net proceeds of approximately $97.6 million of the initial cash payment from Astellas, after payments to KHK and strategic, legal and financial advisors. In December 2012, the Company received a $15.0 million milestone payment from Astellas in connection with the acceptance by the FDA of the NDA filing for tivozanib. The milestone was considered substantive and revenue was recognized upon achievement of the milestone.
	The Company is accounting for the joint development and commercialization activities in North America and Europe as a joint risk-sharing collaboration in accordance with ASC 808, Collaborative Arrangements. In addition, these activities were not deemed to be separate deliverables under the Astellas Agreement.
	Payments from Astellas with respect to Astellas’ share of tivozanib development and commercialization costs incurred by the Company pursuant to the joint development plan are recorded as a reduction to research and development expense and general and administrative expense in the accompanying consolidated financial statements due to the joint risk-sharing nature of the activities in North America and Europe. As a result of the cost-sharing provisions in the Astellas Agreement, the Company reduced research and development expense by $15.8 million, $34.1 million and $26.7 million during the years ended December 31, 2013, 2012, and 2011, respectively. The Company also reduced general and administrative expense by $2.8 million, $3.3 million, and $1.2 million during the years ended December 31, 2013, 2012 and 2011, respectively, as a result of the cost-sharing provisions in the Astellas Agreement. The net amount due to the Company from Astellas pursuant to the cost-sharing provisions was $1.0 million at December 31, 2013.
	Activities under the Astellas Agreement outside of the joint development and commercialization activities in North America and Europe, including the co-exclusive license to develop and commercialize tivozanib in North America and Europe that was delivered prior to the initiation of the collaborative activities in North America and Europe, were evaluated under ASC 605-25, Revenue Recognition—Multiple Element Arrangements (“ASC 605-25”) (as amended by ASU 2009-13, Revenue Recognition (“ASU 2009-13”)) to determine if they represented a multiple element revenue arrangement. The Astellas Agreement includes the following deliverables: (1) a co-exclusive license to develop and commercialize tivozanib in North America and Europe (the “License Deliverable”); (2) a combined deliverable comprised of an exclusive royalty-bearing license to develop and commercialize tivozanib in the Royalty Territory and the Company’s obligation to provide access to clinical and regulatory information resulting from the activities in North America and Europe to Astellas for its development and commercialization of tivozanib in the Royalty Territory (the “Royalty Territory Deliverable”); and (3) the Company’s obligation to supply clinical material to Astellas for development of tivozanib in the Royalty Territory (the “Clinical Material Deliverable”). The License Deliverable is not sublicensable. Astellas has the right to sublicense the exclusive royalty-bearing license to develop and commercialize tivozanib in the Royalty Territory. The Company’s obligation to provide access to clinical and regulatory information as part of the Royalty Territory Deliverable includes the obligation to provide access, upon request, to all clinical data, regulatory filings, safety data and manufacturing data to Astellas for use in the development and commercialization of tivozanib in the Royalty Territory. The Clinical Material Deliverable includes the obligation to supply clinical material to Astellas in accordance with current good manufacturing practices applicable to clinical materials and other relevant regulatory authority requirements, upon request, for the development of tivozanib in the Royalty Territory. All of these deliverables were deemed to have stand-alone value and to meet the criteria to be accounted for as separate units of accounting under ASC 605-25. Factors considered in this determination included, among other things, the subject of the licenses and the research and development and commercial capabilities of Astellas.
	The Company allocated the up-front consideration of $125.0 million to the deliverables based on management’s best estimate of selling price of each deliverable using the relative selling price method as the Company did not have VSOE or TPE of selling price for such deliverables. The Company’s best estimate of selling price considered discounted cash flow models, the key assumptions of which included the market opportunity for commercialization of tivozanib in North America and Europe and the Royalty Territory, the probability of successfully developing and commercializing tivozanib, the remaining development costs for tivozanib, and the estimated time to commercialization of tivozanib. The Company’s analysis included the following market conditions and entity-specific factors: (a) the specific rights provided under the license to develop and commercialize tivozanib in North America and Europe and the Royalty Territory, (b) the potential indications for tivozanib pursuant to the licenses, (c) the relevant territories for the respective licenses, (d) the stage of development of tivozanib by potential indication and estimated remaining development timelines and costs for each indication, (e) the development risk by indication, (f) the market size by indication, (g) the expected product life of tivozanib assuming commercialization and (h) the competitive environment. More specifically, the Company’s discounted cash flow model included an assumption that the Company and Astellas would develop and commercialize tivozanib in North America and Europe as a monotherapy for RCC, and in combination with other known anti-cancer agents for RCC, breast cancer and colorectal cancer. Approximately 70% of the value of tivozanib in the discounted cash flow model was a result of the estimated market opportunity for tivozanib as a monotherapy for RCC. The market opportunity for commercialization of tivozanib in North America and Europe was generated using a patient-based forecasting approach, with key epidemiological, market penetration, dosing, compliance, length of treatment, and pricing assumptions derived from primary and secondary market research. While the RCC monotherapy opportunity represented the majority of the market opportunity, clinical trials for tivozanib in the breast cancer and colorectal cancer indications were in earlier stages of development and therefore had more development risk and were assigned a lower probability of success relative to the RCC indication, with a longer timeline to potential cash inflows. The probability of successfully developing and commercializing tivozanib in the various indications throughout the world (other than Asia) was estimated based on standard industry averages for similar product candidates being developed for oncology indications. The remaining development costs were estimated based upon budgets and estimated costs for ongoing and planned clinical trials in all contemplated indications. The time to commercialization was based on the Company’s estimates, which projected the launch of tivozanib for RCC monotherapy in 2013. The market opportunity for the Royalty Territory was estimated based upon a specified percentage of total projected European sales and costs of tivozanib. The Company believes that this method for estimating market opportunity outside of North America, Europe and Asia is common in the pharmaceuticals industry. The Company utilized a discount rate of 15% in its analysis, representing the weighted average cost of capital derived from returns on equity for comparable companies.
	The Company concluded that a change in the key assumptions used to determine best estimate of selling price for each license deliverable would not have a significant effect on the allocation of arrangement consideration.
	The Company allocated up-front consideration of $120.2 million to the License Deliverable and up-front consideration of $4.8 million to the Royalty Territory Deliverable. The relative selling price of the Company’s obligation under the Clinical Material Deliverable had de minimis value.
	The Company recorded the $120.2 million relative selling price of the License Deliverable as collaboration revenue during the three months ended March 31, 2011 upon delivery of the license, and deferred approximately $4.8 million of revenue representing the relative selling price of the Royalty Territory Deliverable. The Company is recording the $4.8 million of revenue attributed to the Royalty Territory Deliverable ratably over the Company’s period of performance through April 2022, the remaining patent life of tivozanib. The Company estimated the period of performance considering that the Company and Astellas plan to develop tivozanib in several indications outside of RCC, including in breast cancer and colorectal cancer and potentially in other cancer indications. The clinical development of tivozanib in these indications is in earlier stages of development and, as a result, the clinical development timeline is uncertain and is expected to change as the Company obtains additional clinical data in these indications. As a result, the Company estimated the period of performance as the remaining patent life of tivozanib as it represents the longest period over which development of tivozanib could occur. The Company reassesses the period of performance at each reporting period. The Company recorded approximately $0.4 million of revenue associated with the Royalty Territory Deliverable during each of the years ended December 31, 2013, 2012 and 2011.
	Under the agreement, the Company received cash payments related to up-front license fees, reimbursable payments and milestone payments of $40.1, $39.8 million, and $146.4 million during the years ended December 31, 2013, 2012 and 2011, respectively, and recorded revenue of $0.4 million, $15.4 million and $120.6 million during the years ended December 31, 2013, 2012 and 2011, respectively.
	Biogen Idec International GmbH
	In March 2009, the Company entered into an exclusive option and license agreement with Biogen Idec International GmbH, a subsidiary of Biogen Idec Inc., collectively referred to herein as “Biogen Idec”, regarding the development and commercialization of the Company’s discovery-stage ErbB3-targeted antibodies for the potential treatment and diagnosis of cancer and other diseases outside of North America. Under the agreement, the Company is responsible for developing ErbB3 antibodies through completion of the first phase 2 clinical trial designed in a manner that, if successful, will generate data sufficient to support advancement to a phase 3 clinical trial. Until a specified time after the Company completes this phase 2 clinical trial and delivers to Biogen Idec a detailed data package containing the results thereof, Biogen Idec may elect to obtain (1) a co-exclusive (with the Company), worldwide license, including the right to grant sublicenses, under the Company’s relevant intellectual property to develop and manufacture ErbB3 antibody products, and (2) an exclusive license, including the right to grant sublicenses, under the Company’s relevant intellectual property, to commercialize ErbB3 antibody products in all countries in the world other than North America. The Company retains the exclusive right to commercialize ErbB3 antibody products in North America.
	The Company accounts for the Biogen Idec arrangement pursuant to ASC 605-25. The deliverables under the arrangement include an option for a co-exclusive, worldwide license to develop and manufacture ErbB3 antibody products and an option for an exclusive license to commercialize ErbB3 antibody products in all countries in the world other than North America. The Company determined that these deliverables did not have standalone value due to the fact that the program was still in preclinical development and required the Company’s experience to advance development of the product. As such, the Company determined that the agreement should be accounted for as one unit of accounting.
	Under the terms of the agreement, Biogen Idec paid the Company an up-front cash payment of $5.0 million in March 2009, which is being amortized over the Company’s period of substantial involvement, defined as the patent life of the development candidate. In addition, Biogen Idec purchased 7,500,000 shares of Series E Convertible Preferred Stock at a per share price of $4.00, resulting in gross proceeds to the Company of $30.0 million. In connection with the initial public offering consummated by the Company in March 2010 and the related 1:4 reverse stock split of the common stock, each four shares of outstanding Series E Convertible Preferred Stock were converted into one share of common stock. The Company determined that the per share price of $4.00 paid by Biogen Idec included a premium of $1.09 per share over the fair value of the Series E Convertible Preferred Stock of $2.91 as calculated by the Company in its retrospective stock valuation. Accordingly, the Company is recognizing the premium of $8.2 million as revenue on a straight-line basis over the period of substantial involvement. The Company earned a $5.0 million milestone payment for achievement of the first pre-clinical discovery milestone under the agreement in June 2009 which was not considered at risk and was therefore deferred and is being recognized over the period of substantial involvement. The Company earned a second $5.0 million milestone payment upon selection of a development candidate in March 2010. This milestone was considered substantive and was included in revenue for the quarter ended March 31, 2010. The Company earned a third $5.0 million milestone payment based on achieving the GLP toxicology initiation milestone in June 2011. This milestone was considered substantive and was included in revenue for the quarter ended June 30, 2011. The Company could also receive an option exercise fee of $5.0 million and regulatory milestone payments of up to $45.0 million in the aggregate if Biogen Idec exercises its option to obtain exclusive rights to commercialize ErbB3 antibody products in its territory. The first regulatory milestone that the Company may receive pursuant to this agreement of $25.0 million is due upon the receipt of the first regulatory approval of a licensed product from the EMA. The Company does not expect to achieve this milestone in the near future. The Company did not earn any milestones under this arrangement during the year ended December 31, 2013.
	If Biogen Idec exercises its exclusive option under the agreement, Biogen Idec will pay the Company royalties on Biogen Idec’s sales of ErbB3 antibody products in its territory, and the Company will pay Biogen Idec royalties on the Company’s sale of ErbB3 antibody products in North America.
	Under the agreement, the Company received cash payments related to up-front license fees, milestone payments, and equity of $5.0 million during the year ended December 31, 2011, and recorded revenue of $0.9 million, $0.9 million and $5.9 million during the years ended December 31, 2013, 2012 and 2011, respectively.
	OSI Pharmaceuticals Inc.
	In September 2007, the Company entered into a collaboration and license agreement with OSI Pharmaceuticals, Inc. (a wholly-owned subsidiary of Astellas US Holding Inc., a holding company owned by Astellas Pharma Inc.), or OSI, which provided for the use of the Company’s proprietary in vivo models by the Company’s scientists at its facilities, use of the Company’s bioinformatics tools and other target validation and biomarker research to further develop and advance OSI’s small molecule drug discovery and translational research related to cancer and other diseases. In July 2009, the Company and OSI expanded the strategic partnership, and the Company granted OSI a non-exclusive license to use the Company’s proprietary bioinformatics platform, and non-exclusive perpetual licenses to use bioinformatics data and the Company’s proprietary gene index related to a specific target pathway. Further, as part of the expanded strategic partnership, the Company granted OSI an option, exercisable upon payment of an option fee, to receive non-exclusive perpetual rights to certain elements of the Company’s Human Response Platform and to use the Company’s bioinformatics platform, and the Company granted OSI the right to obtain certain of its tumor models and tumor archives.
	The Company accounted for the OSI arrangement pursuant to ASC 605-25. The deliverables under the arrangement were accounted for as a single unit of accounting. OSI paid the Company an up-front payment of $7.5 million, which was recognized as revenue through July 2011 (the date the Company satisfied its performance obligations under the OSI arrangement). OSI also paid the Company $2.5 million for the first year of research program funding, which was recognized as revenue over the performance period and, thereafter, OSI made research payments of $0.6 million per quarter through July 2009. In addition, OSI purchased 1,833,334 shares of Series C Convertible Preferred Stock, at a per share price of $3.00, resulting in gross proceeds to the Company of $5.5 million. The Company determined that the price paid of $3.00 per share by OSI included a premium of $0.50 over the price per share of the Company’s Series D Convertible Preferred Stock sold in April 2007; accordingly, the Company recognized the premium of $0.9 million as additional license revenue on a straight-line basis through July 2011. In connection with the initial public offering consummated by the Company in March 2010 and the related 1:4 reverse stock split of the common stock, each four shares of outstanding Series C Convertible Preferred Stock were converted into one share of common stock.
	In consideration for the additional rights provided for pursuant to the July 2009 expanded agreement, OSI paid the Company an up-front payment of $5.0 million, which was recognized as revenue ratably through July 2011. OSI also agreed to fund research costs through June 30, 2011. In addition, OSI purchased 3,750,000 shares of Series E Convertible Preferred Stock, at a per share price of $4.00, resulting in gross proceeds to the Company of $15.0 million. In connection with the initial public offering consummated by the Company in March 2010 and the related 1:4 reverse stock split of the common stock, each four shares of outstanding Series E Convertible Preferred Stock were converted into one share of common stock. The Company determined that the price of $4.00 per share paid by OSI included a premium of $1.04 per share over the fair value of the Series E Convertible Preferred Stock of $2.96 as calculated by the Company in its retrospective stock valuation. Accordingly, the Company recognized the premium of $3.9 million as additional license revenue ratably through July 2011.
	Under the July 2009 expanded agreement, if all applicable milestones are achieved, all remaining payments for the successful achievement of discovery, development and commercialization milestones could total, in the aggregate, over $46.0 million, comprised of approximately (i) $8.4 million in substantive milestone payments upon achievement of specified clinical and development milestone events, (ii) $20.7 million in substantive milestone payments upon achievement of specified regulatory milestone events, and (iii) $17.5 million in milestone payments upon the achievement of specified sales events. In addition, the Company is eligible to receive up to $24.0 million in biomarker-related milestones.
	In March 2011, the Company earned $1.5 million related to achieving certain of the biomarker-related milestones under the agreement. These milestones were not considered to be substantive; therefore, the $1.5 million in payments was deferred and was recognized ratably through July 2011. In May 2012, the Company earned a patent-related milestone payment of $0.3 million upon filing of a patent application by OSI, and the Company also earned a clinical and development milestone payment of $0.8 million for commencement by OSI of GLP toxicology studies. Since these milestones were considered substantive, they were recorded as revenue during the year ended December 31, 2012.
	The next milestone payment that the Company may receive pursuant to this agreement is a $2.0 million clinical and development milestone for phase 1 clinical trial dosing in the United States. The Company does not expect to achieve this milestone in the near future. The next regulatory milestone payment the Company may receive pursuant to this agreement is $7.0 million to be achieved for the filing of an NDA with the FDA. The Company does not expect to achieve this milestone in the near future. Upon commercialization of products under the agreement, the Company is eligible to receive tiered royalty payments on sales of products by OSI, its affiliates and sublicensees. All milestone payments earned prior to July 2011 are for selection of targets, delivery of models, delivery of tumor archives or delivery of cell lines.
	In November 2010, OSI exercised its option under the July 2009 expanded agreement providing the right for OSI to license certain elements of the Company’s proprietary technology platform, including components of the Human Response Platform for the identification/characterization of novel epithelial-mesenchymal transition agents and proprietary patient selection biomarkers, in support of OSI’s clinical development programs. The Company did not consider the option granted to OSI in July 2009 as a deliverable as there was significant uncertainty that this option would ultimately be exercised. The Company received $12.5 million upon delivery of the notice of option exercise, and completed the transfer of the relevant technology to OSI in July 2011. The remaining $12.5 million was paid in July 2011 following the successful transfer of the applicable technology. The Company deferred the initial $12.5 million payment, and recognized the full $25.0 million relating to the option exercise by OSI over the technology transfer period, which was completed in July 2011.
	Under these agreements, the Company received cash payments related to up-front license fees, milestone payments, research and development funding and purchase of equity of $1.0 million and $16.5 million, and recorded revenue of $1.0 million and $29.6 million, during the years ended December 31, 2012 and 2011, respectively.
	Centocor Ortho Biotech Inc.
	In May 2011, the Company entered into an exclusive license agreement (the “Centocor License Agreement”) with Centocor Ortho Biotech Inc. (“Centocor”), for the worldwide development and commercialization of the Company’s internally-discovered antibodies targeting the RON receptor (Recepteur d’Origine Nantais), including the grant to Centocor of an exclusive, worldwide license to the Company’s proprietary RON-driven tumor models. The Company also granted Centocor a non-exclusive, non-sublicensable, worldwide license to the Company’s proprietary list of human genes intended to predict correlation of response to RON-targeted antibodies (the “RON index”). On September 7, 2012, the Company received notice from Centocor of termination of the Centocor License Agreement, effective on December 6, 2012, at which point all rights to and the responsibility for future research and development, manufacturing and commercialization activities and costs of the RON antibody program granted to Centocor under the Centocor License Agreement returned to the Company.
	In connection with the Centocor License Agreement, the Company received a one-time cash payment in the amount of $7.5 million and a separate equity investment in the amount of approximately $7.5 million through the purchase by Johnson & Johnson Development Corporation, an affiliate of Centocor, of 438,340 newly issued shares of the Company’s common stock at a purchase price of $17.11 per share, which reflected the average of the daily volume weighted average prices for the Company’s common stock for the 30 consecutive trading days ending on May 26, 2011. This weighted average sales price of $17.11 per share resulted in a $1.22 per share discount from the May 31, 2011 closing price of $18.33 per share, or a discount of $534,775 from the fair market value of the common stock on the effective date of the Centocor License Agreement. The Company determined this transaction was not within the scope of ASC 605-25 and, accordingly, the Company recorded the sale of common stock to Johnson & Johnson Development Corporation at fair value based on the closing price of the Company’s stock on May 31, 2011 of $18.33 per share. Centocor also funded certain research which the Company conducted during the term of the Centocor License Agreement, which, as noted above, terminated on December 6, 2012.
	The remaining activities under the Centocor License Agreement were evaluated under ASC 605-25 (as amended by ASU 2009-13) to determine if they represented a multiple element revenue arrangement. The Company determined that the Centocor License Agreement included the following deliverables:
		•	an exclusive, sublicensable commercialization and development license related to RON antibodies (the “RON license”);
		•	a non-exclusive license to use the Company’s RON index (the “RON Index license”); and
		•	the Company’s obligation to provide research services.
	The Company determined that each deliverable had stand-alone value upon delivery and therefore represents a separate unit of accounting. Factors considered in this determination included, among other things, the subject of the licenses and the research and development and commercial capabilities of Centocor.
	The Company excluded the fair value of the common stock purchased by Johnson & Johnson Development Corporation from the arrangement consideration to be allocated to the identified deliverables and allocated the remaining $7.0 million of up-front consideration attributable to the deliverables based on the relative selling price method. The Company determined the estimated selling price for the RON license and the RON Index license based on management’s best estimate of selling price as the Company did not have VSOE or TPE of selling price for those deliverables. In determining its best estimate of selling price for the RON license and the RON Index license, the Company considered market conditions as well as entity-specific factors, including those factors contemplated in negotiating the Centocor License Agreement and internally developed revenue models. The Company’s best estimate of selling price for the RON license and RON Index license considered discounted cash flow models, the key assumptions of which included the market opportunity for commercialization of a potential product candidate using the RON receptor worldwide, an estimate of costs related to phase 1, 2 and 3 clinical studies with certain multiplication factors related to the probability of success, and the time to commercialization of a potential product candidate. This analysis used various assumptions that the Company believed were typical for similarly staged monoclonal antibodies and what it believed to be reasonable cost assumptions in determining research and development, and sales, general and administrative costs. More specifically, the Company believed that its estimate of peak revenues was consistent with what might be expected from an approved antibody product. Other key assumptions included: cost of goods sold, which was assumed to be a specified percentage of revenues based on estimated cost of goods sold of a typical oncology antibody product; clinical trial costs, which were based on estimated clinical costs for a single phase 1 safety study, followed by phase 2 and 3 studies for a single oncology indication; and sales and marketing costs, which were based on the costs required to field an oncology sales force and marketing group, including external costs required to promote an oncology product. The factors used to estimate the probability of success and the time to commercialization of a product candidate were based on standard industry averages for antibodies being developed for oncology indications. The results of the Company’s analysis indicated an estimated selling price for the licenses of approximately $39 million. The analysis used a weighted average cost of capital of 15% derived from returns on equity for comparable companies.
	With respect to the research services, the Company considered the nature of the research services to be provided (basic translational research related to a pre-clinical, antibody-based technology) and the fact that other vendors could provide the research services. As a result, the Company concluded that TPE of selling price existed for the research services deliverable. In supporting TPE of selling price, the Company considered the nature of the research services, the rates charged by vendors in the marketplace for similar services and rates charged by the Company for other non-complex, pre-clinical research services in its other license and development agreements.
	As the relative selling price of the RON license and RON Index license (the delivered items) exceeded the up-front consideration attributable to the deliverables of $7.0 million, the entire up-front payment was recognized as revenue upon delivery of the licenses during the three months ended June 30, 2011. The Company concluded that a change in the assumptions used to determine estimated selling price for the units of accounting would not have a significant effect on the allocation of arrangement consideration.
	The Company recorded revenue related to research and development services as the services were delivered at the contractual rate, which approximated fair value for those services. Under the agreement, the Company received cash payments related to up-front license fees, research and development services, and the purchase of equity of $2.3 million and $16.3 million, and recorded revenue of $2.0 million and $8.8 million, during the years ended December 31, 2012 and 2011, respectively. The Company did not recognize any revenue related to milestones under this arrangement.
	Schering-Plough Corporation (now Merck)
	In March 2007, the Company entered into an agreement with Schering-Plough Corporation (now Merck), through its subsidiary Schering Corporation, acting through its Schering-Plough Research Institute division, under which the Company granted Merck exclusive, worldwide rights to develop and commercialize all of our monoclonal antibody antagonists of HGF, including ficlatuzumab, for therapeutic and prophylactic use in humans and for veterinary use. The Company also granted Merck an exclusive, worldwide license to related biomarkers for diagnostic use. Merck was responsible for all costs related to the clinical development of ficlatuzumab and clinical and commercial manufacturing. As of December 27, 2010, the effective date of the termination of the Company’s collaboration with Merck relating to ficlatuzumab, the Company became responsible for all process development and all manufacturing of ficlatuzumab for future development and commercialization. In March 2011, in connection with the transition of responsibility for the ficlatuzumab program from Merck back to the Company, the Company made a $10.2 million payment to Merck for the purchase of a supply of ficlatuzumab to support ongoing clinical studies and expensed such payment during the year ended December 31, 2011, as title passed to the Company.
	(b) In-license Agreements
	Kirin Brewery Co. Ltd. (KHK)
	In December 2006, the Company entered into an exclusive license agreement, with the right to grant sublicenses, subject to certain restrictions, with Kirin Brewery Co. Ltd. (now Kyowa Hakko Kirin) (“KHK”) to research, develop, manufacture and commercialize tivozanib, pharmaceutical compositions thereof and associated biomarkers in all territories in the world except for Asia (the “KHK Agreement”). Upon entering into the KHK Agreement, the Company made a cash payment in the amount of $5.0 million.
	In March 2010, the Company made a $10.0 million milestone payment to KHK in connection with the dosing of the first patient in the Company’s phase 3 clinical trial of tivozanib. The Company recorded $22.5 million of research and development expense during the year ended December 31, 2011 associated with a payment made to KHK related to the up-front license payment received under the Astellas Agreement. In December 2012, the Company made a $12.0 million milestone payment to KHK in connection with the acceptance by the FDA of the Company’s NDA filing for tivozanib, all of which was expensed as research and development expense during the year ended December 31, 2012. In connection with this payment, $6.0 million was reimbursed from Astellas and recorded as a reduction of research and development expense.
	Under the KHK Agreement, the Company may be required to (i) make future milestone payments upon the achievement of specified regulatory milestones in the United States, including a possible milestone payment of $18.0 million to KHK in connection with the FDA granting marketing approval in the United States, (ii) pay tiered royalty payments on net sales it makes of tivozanib in its territory ranging from the low to mid-teens as a percentage of the Company’s net sales of tivozanib, and (iii) pay 30% of certain amounts the Company receives under the Astellas Agreement in connection with Astellas’ development and commercialization activities in Europe and the Royalty Territory related to tivozanib, including up-front license fees, milestone payments and royalties the Company may receive from Astellas (including a potential $4.5 million milestone payable to KHK in connection with the acceptance by the EMA of the filing of a Marketing Authorization Application and $9.0 million to KHK in connection with the EMA granting marketing approval in Europe), other than amounts the Company receives in respect of research and development funding or equity investments, subject to certain limitations.
	The license agreement will remain in effect until the expiration of all of the Company’s royalty and sublicense revenue obligations to KHK unless either party elects to terminate the license agreement earlier. If the Company fails to meet its obligations under the agreements and is unable to cure such failure within specified time periods, KHK can terminate the agreement, resulting in a loss of the Company’s rights to tivozanib and an obligation to assign or license to KHK any intellectual property rights the Company may have in tivozanib.
	St. Vincent’s Hospital
	In July 2012, the Company entered into a license agreement with St Vincent’s Hospital Sydney Limited, which the Company refers to as St. Vincent’s, under which the Company obtained an exclusive, worldwide license, with the right to grant sublicenses subject to certain restrictions, under specified patent rights and related know-how, to research, develop, manufacture and commercialize products for human therapeutic, preventative and palliative applications that benefit from inhibition or decreased expression or activity of MIC-1, which the Company refers to as GDF-15. The Company is exploiting this license in its AV-380 program for cachexia. The Company has a right of first negotiation to obtain an exclusive license to certain improvements that St. Vincent’s or third parties may make to licensed therapeutic products. Under the license agreement, St. Vincent’s also granted us non-exclusive rights for certain related diagnostic products and research tools.
	Under the license agreement, the Company is obligated to use diligent efforts to conduct research and clinical development and commercially launch at least one licensed therapeutic product, and to maximize profits from licensed therapeutic products for the benefit of us and St. Vincent’s. Subject to certain conditions, the Company has also agreed to achieve specified research, development and regulatory milestones by specified dates. If the Company does not achieve a given milestone by the agreed date, the Company has the option of paying the amount the Company would have been obligated to pay had the Company timely achieved the milestone, and, if the Company does so, St. Vincent’s will not have the right to terminate the license agreement based on its failure to timely achieve such milestone.
	The Company has also agreed that, for as long as there is a valid claim in the licensed patents, the Company will not, and the Company will ensure that its affiliates and its sublicensees do not, develop or commercialize any product, other than a licensed therapeutic product, for the treatment, prevention or prophylaxis of cachexia, decreased appetite or body weight, that binds to GDF-15 or the GDF-15 receptor and that is a GDF-15 antagonist, and will not license or induce any other person to do the same.
	In connection with entering into the license agreement with St. Vincent’s, the Company paid St. Vincent’s an upfront license fee of $0.7 million and a low five-figure amount to reimburse St. Vincent’s for patent-related expenses it incurred with respect to a specified licensed patent.
	Under the Company’s license agreement with St. Vincent’s, the Company may be required to:
		•	make milestone payments, up to an aggregate total of $9.2 million, upon achievement of specified research, development and regulatory milestones for the first three indications for licensed therapeutic products, some of which payments may be increased by a mid to high double-digit percentage rate for milestones payments made after the Company grants any sublicense under the license agreement, depending on the sublicensed territory or territories;
		•	pay tiered royalty payments equal to a low-single-digit percentage of any net sales the Company or its sublicensees make of licensed therapeutic products. The royalty rate escalates within the low-single-digit range during each calendar year based on increasing licensed therapeutic product sales during such calendar year. The Company’s royalty payment obligations for a licensed therapeutic product in a particular country end on the later of 10 years after the date of first commercial sale of such licensed therapeutic product in such country or expiration of the last-to-expire valid claim of the licensed patents covering such licensed therapeutic product in such country, and are subject to offsets under certain circumstances;
		•	pay St. Vincent’s sublicensing fees of up to an aggregate amount in the low-to-mid six-digits, depending on the sublicensed territory or territories, at the time the Company grants any sublicense; and
		•	reimburse St. Vincent’s for some or all of the reasonable costs and expenses it incurs in patent management, filing, prosecuting and maintaining the licensed patents.
	The license agreement will remain in effect until the later of 10 years after the date of first commercial sale of licensed therapeutic products in the last country in which a commercial sale is made, or expiration of the last-to-expire valid claim of the licensed patents, unless the Company elects, or St. Vincent’s elects, to terminate the license agreement earlier.
	Either party has the right to terminate the agreement in connection with a material breach of the agreement by the other party that remains uncured for a specified cure period, or in connection with events relating to the other party’s insolvency or bankruptcy, or if a force majeure event continues for more than 4 months.
	St. Vincent’s has the right to terminate the agreement due to any patent-related challenge by the Company, its affiliates or any sublicensee, or if the Company or its affiliates or any sublicensee cause or induce any other person to make a patent-related challenge, and such challenge continues after a specified cure period.
The Company has the right to terminate the agreement on 6 months’ notice if the Company terminates its GDF-15 research and development programs as a result of the failure of a licensed therapeutic product in pre-clinical or clinical development, or if the Company forms the reasonable view that further GDF-15 research and development is not commercially viable, and the Company is not then in breach of any of its obligations under the agreement. If the Company forms the reasonable view that further GDF-15 research and development is not commercially viable and terminate the agreement before the Company starts a phase 1 clinical trial on a licensed therapeutic product, the Company will be required to pay St. Vincent’s a low-to-mid six-figure termination payment.
The Company may also terminate the agreement on 60 days’ notice if certain licensed patents become invalid or unenforceable prior to July 2014, are not in breach of any of the Company’s obligations under the agreement, and the Company, its affiliates and sublicensees have not made a patent-related challenge.
Any termination of the agreement, in whole or in part, will result in a loss of the Company’s rights to the relevant licensed patents and know-how. If St. Vincent’s terminates the agreement in its entirety due to the Company’s breach, insolvency or a patent-related challenge, or the Company terminates the agreement due to a development failure or lack of commercial viability, as described above, St. Vincent’s will have a non-exclusive license from us to certain intellectual property rights and know-how relating to the licensed therapeutic products, and the Company must transfer to St. Vincent’s certain then-existing regulatory approvals and related documents for the licensed therapeutic products.
Other License Agreements
The Company has entered into various cancelable license agreements for patented technology and other technology related to research projects, including technology to humanize ficlatuzumab, AV-203 and other antibody product candidates. The Company is obligated to pay annual maintenance payments of $25,000, which are recognized as research and development expense over the maintenance period. Under an additional agreement, if the parties agree to the use of the licensed technology in development of a product, the Company will be required to make a $1.0 million license payment per product. Three of these agreements also include development and sales-based milestones of up to $22.5 million, $5.5 million and $4.2 million per product, respectively, and single digit royalties as a percentage of sales.
Certain other research agreements require the Company to remit royalties in amounts ranging from 0.5% to 1.5% based on net sales of products utilizing the licensed technology. Total license expense incurred under these other license agreements amounted to $0.3 million and $0.5 million during the years ended December 31, 2012 and 2011, respectively. No expenses were incurred during the year ended December 31, 2013. The Company has not paid any royalties to date.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies	'
	8	Commitments and Contingencies
	Operating Leases
	The Company leases office and lab space and equipment under various operating lease agreements. Rent expense under the operating leases amounted to $9.4 million, $7.8 million and $2.7 million for the years ended December 31, 2013, 2012 and 2011, respectively.
	In July 2004, the Company entered into a sublease agreement with Millennium Pharmaceuticals, Inc., to sublease 55,200 square feet of office and lab space located at 75 Sidney Street in Cambridge, MA. The sublease expired on February 28, 2014. In conjunction with the signing of this lease, the Company entered into a standby letter of credit in the amount of $0.6 million to expire on July 12, 2005, subject to automatic extensions for periods of one year as a security deposit on said lease. The letter of credit has been collateralized by a money market account held by the bank which issued the letter of credit and has been automatically extended through July 12, 2014. The Company has classified this money market account within restricted cash on its balance sheets at December 31, 2013 and 2012. The Company received six free months of rent under this arrangement and has recorded rent on a straight-line basis over the lease term resulting in deferred rent of approximately $42,000 and $0.3 million at December 31, 2013 and 2012, respectively.
	On February 28, 2011, the Company entered into a sublease agreement with Acceleron Pharma, Inc. to sublease 14,214 square feet of office space located at 12 Emily Street in Cambridge, MA. The sublease will expire on May 30, 2015. In conjunction with the lease, the Company entered into a standby letter of credit in the amount of $0.1 million, which will expire on May 31, 2014 subject to automatic extensions for periods of one year related to the term of the sublease. The letter of credit has been collateralized by a money market account held by the bank which issued the letter of credit. The Company has classified the money market account within restricted cash on its balance sheet at December 31, 2013 and 2012. This sublease has scheduled increases in rent payments over the period of the lease and the Company has recorded rent on a straight-line basis over the lease term resulting in deferred rent of approximately $19,000 and $32,000 at December 31, 2013 and 2012, respectively.
	On November 4, 2011, the Company entered into a lease agreement with the Massachusetts Institute of Technology, to lease an additional 11,500 square feet of office space located at 12 Emily Street in Cambridge, MA. The lease commenced on December 15, 2011 and expired on February 28, 2014. Subject to the terms of the lease, the Company could have extended the term until May 31, 2015 but did not elect to do so. In conjunction with the lease, the Company entered into a standby letter of credit in the amount of $46,000 which will expire on April 29, 2013, subject to an automatic extension period of one year related to the term of the sublease. The letter of credit has been collateralized by a money market account held by the bank which issued the letter of credit. The Company has classified the money market account within restricted cash on its balance sheet at December 31, 2013 and 2012. As part of this lease, the Company obtained a tenant improvement allowance in the amount of $115,000 to be used for costs incurred by the tenant for the tenant’s work. The Company used all of this allowance as of December 31, 2012. The Company also received six free weeks of rent under this arrangement and has recorded rent on a straight-line basis over the lease term, resulting in deferred rent of approximately $13,000 and $82,000 at December 31, 2013 and 2012, respectively.
	On May 9, 2012, the Company entered into a lease agreement with BMR-650 E KENDALL B LLC (“BMR”), under which the Company has agreed to lease 126,065 square feet of space located at 650 East Kendall Street, Cambridge, Massachusetts to be used for office, research and laboratory space. The initial term of the lease agreement is approximately twelve years and seven months (the “initial term”), and the Company has the right to extend the initial term for two additional terms of five years each. The Company’s occupancy of the space will occur in two phases. The Company began the phase one occupancy on January 4, 2013 when the Company began to move some employees to occupy 26,734 square feet of office space (the “phase 1 space”). The Company expects the second phase to consist of the balance of the Company’s employees moving into the remaining space (the “phase 2 space”) and is expected to occur during the second half of 2014. Rent payments with respect the phase 1 space commenced on January 1, 2013, and rent payments for the phase 2 space commenced on November 1, 2013 for the phase 2 space. The initial base rent expense for both the phase 1 space and the phase 2 space is $54.50 per rentable square foot per year, with 3% increases on each anniversary of the phase 1 space rent commencement date. In addition to the base rent, the Company is also responsible for its share of operating expenses and real estate taxes. In accordance with the terms of the lease agreement, the Company maintains a letter of credit securing its obligations under the lease agreement of approximately $2.9 million. The Company has determined that the lease should be classified as an operating lease. As the Company gained access to both the phase 1 space and the phase 2 space beginning in May 2012, the Company recognized rent expense of approximately $6.7 million and $4.9 million related to the lease during the years ended December 31, 2013 and 2012, respectively.
	In order to make the space usable for the Company’s operations, substantial improvements have been and will continue to be made to the space. These improvements are being planned, managed and carried out by the Company and the improvements are being tailored to the Company’s needs. BMR has agreed to reimburse the Company for up to approximately $20.0 million of the improvements, and the Company bears all risks associated with any cost overruns that may be incurred. As such, the Company determined it was the owner of the improvements and, as such, the Company accounts for tenant improvement reimbursements from BMR as a lease incentive. The Company records a deferred lease incentive (included as a component of the deferred rent balance in the accompanying consolidated balance sheets) as improvements are made to the facility, and this deferred lease incentive will be amortized as an offset to rent expense over the term of the lease. Rent expense, inclusive of the escalating rent payments, is being recognized on a straight-line basis over the initial term of the lease agreement, as well as the tenant improvement allowance, resulting in deferred rent of approximately $20.0 million and $11.0 million at December 31, 2013 and 2012, respectively. The Company is amortizing all improvements over the assets’ useful lives or the lease term, whichever is shorter. Amortization of leasehold improvements is included as a component of depreciation expense.
	Future annual minimum lease payments under all noncancelable operating leases at December 31, 2013 are as follows (amounts in thousands):
	Years Ending December 31:
	2014			8,077
	2015			7,530
	2016			7,508
	2017			7,733
	2018 and thereafter			61,030
			$	91,878
	Employment Agreements
	Certain key executives are covered by severance and change in control agreements. Under these agreements, if the executive’s employment is terminated without cause or if the executive terminates his employment for good reason, such executive will be entitled to receive severance equal to his base salary, benefits and prorated bonuses for a period of time equal to either 12 months or 18 months, depending on the terms of such executive’s individual agreement. In addition, in December 2007, the Company approved a key employee change in control severance benefits plan, which was amended in November 2009, and which provides for severance and other benefits under certain qualifying termination events upon a change in control for a period of time ranging from 6 months to 18 months, depending upon the position of the key employee.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Taxes	'
	9	Income Taxes
	For the years ended December 31, 2013 and 2012, the Company did not have any federal, state, or foreign income tax expense as it generated taxable losses in all filing jurisdictions. For the year ended December 31, 2011, the Company was able to utilize net operating loss carryforwards (NOLs) to fully offset taxable income in all filing jurisdictions.
	A reconciliation of the expected income tax benefit computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows for the years ended December 31, 2013, 2012 and 2011:
			December 31,			December 31,			December 31,
			2013			2012			2011
	Income tax computed at federal statutory tax rate			34	%		34	%		34	%
	State taxes, net of federal benefit			5.1	%		5.1	%		5.3	%
	Research and development credits			2	%		0.1	%		(5.1	)%
	Permanent differences			(0.9	)%		(1.2	)%		2.8	%
	Foreign rate differential			(0.2	)%		(0.4	)%		0	%
	Other			(0.5	)%		(0.2	)%		0.3	%
	Change in valuation allowance			(39.5	)%		(37.4	)%		(37.3	)%
	Total			0	%		0	%		0	%
	Prior to 2011, the Company had incurred net operating losses from inception. At December 31, 2013, the Company had domestic federal, state, and UK net operating loss carryforwards of approximately $348.8 million, $259.9 million, and $6.9 million respectively, available to reduce future taxable income, which expire at various dates. The federal net operating loss carryforwards expire beginning in 2022 through 2033 and the state loss carryforwards begin to expire in 2014 and continue through 2033. The Company also had federal and state research and development tax credit carryforwards of approximately $8.7 million and $4.0 million, respectively, available to reduce future tax liabilities and which expire at various dates. The federal credits expire beginning in 2022 through 2033 and the state credits begin to expire in 2019. The net operating loss and research and development carryforwards are subject to review and possible adjustment by the Internal Revenue Service and may be limited in the event of certain changes in the ownership interest of significant stockholders.
	The Company’s net deferred tax assets as of December 31, 2013 and 2012 are as follows:
			2013			2012
			(in thousands)
	NOL carryforwards		$	134,023		$	99,001
	Research and development credits			11,357			7,960
	Deferred revenue			7,224			7,732
	Other temporary differences			15,158			10,776
	Valuation allowance			(167,762	)		(125,469	)
			$	—		$	—
	A full valuation allowance has been recorded in the accompanying consolidated financial statements to offset these deferred tax assets because the future realizability of such assets is uncertain. This determination is based primarily on the Company’s historical losses. Accordingly, future favorable adjustments to the valuation allowance may be required, if and when circumstances change. The valuation allowance increased by $42.3 million during the year ended December 31, 2013, primarily due to the generation of net operating loss carryforwards.
	As of December 31, 2013, the Company had federal and state net operating losses of approximately $4.1 million related to excess tax deductions that have been excluded from the above table. The benefit of these net operating losses will be recognized as an increase in additional paid in capital when it results in a reduction in taxable income.
	Uncertain tax positions are recognized if the position is more-likely-than-not to be sustained upon examination by a tax authority. Unrecognized tax benefits represent tax positions for which reserves have been established. The Company has recorded a reserve for $1.2 million of unrecognized tax benefits. A full valuation allowance has been provided against the Company’s deferred tax assets, so that the effect of the unrecognized tax benefits is to reduce the gross amount of the deferred tax asset and the corresponding valuation allowance. Since the Company has incurred net operating losses since inception, it has never been subject to a revenue agent review. As a result, all periods since inception remain subject to examination by U.S. federal and Massachusetts tax jurisdictions.
	The Company may from time to time be assessed interest or penalties by major tax jurisdictions. The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. No interest and penalties have been recognized by the Company to date.
	The Company anticipates that the amount of unrecognized tax benefits recorded will not change in the next twelve months.
	The following is a reconciliation of the Company’s gross uncertain tax positions at December 31, 2013 and 2012:
			Year ended			Year ended
			December 31,			December 31,
			2013			2012
			(in thousands)
	Amount established upon adoption		$	1,200		$	1,200
	Additions for current year tax positions			—			—
	Additions for prior year tax positions			—			—
	Reductions of prior year tax positions			—			—
	Balance as of end of year		$	1,200		$	1,200

Common_Stock_and_Warrants

Common Stock and Warrants	12 Months Ended
	Dec. 31, 2013
Common Stock and Warrants	'
	10	Common Stock and Warrants
	As of December 31, 2013, the Company had 100,000,000 authorized shares of common stock, $0.001 par value, of which 51,809,028 shares were issued and outstanding.
	During 2013, all of the Company’s outstanding warrants expired unexercised and, as of December 31, 2013, the Company had no warrants outstanding.
	Private Placements
	On May 31, 2011, the Company entered into a definitive agreement with respect to the sale of 438,340 shares of its unregistered common stock at $17.11 per share to Johnson & Johnson Development Corporation in connection with the Centocor License Agreement. The Company completed the private placement on May 31, 2011, resulting in approximately $7.5 million in proceeds to the Company.
	Public Offering
	In June 2011, the Company raised $100.6 million in gross proceeds from the sale of 5,750,000 shares of its common stock in a public offering at $17.50 per share. In June 2011, the underwriters of the public offering exercised their option to purchase an additional 602,119 shares of common stock at $17.50 per share resulting in additional gross proceeds to the Company of approximately $10.5 million. The combined net offering proceeds after deducting approximately $7.0 million in offering related expenses and underwriters’ discounts and commissions were approximately $104.2 million.
	In January 2013, the Company completed an underwritten public offering of its common stock. The total number of shares sold was 7,667,050, comprised of 6,667,000 shares of common stock initially offered and an additional 1,000,050 shares of common stock sold pursuant to the underwriters’ exercise of their over-allotment option, at the public offering price of $7.50 per share. Aggregate net proceeds to the Company were approximately $53.6 million, after deducting $3.9 million in offering related expenses and underwriting discounts and commissions.

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2013
Stock-Based Compensation	'
	11	Stock-Based Compensation
	Stock Incentive Plan—Overview
	The Company maintains the 2010 Stock Incentive Plan (the “Plan”) for employees, consultants, advisors, and directors. The Plan provides for the grant of equity awards such as stock options and restricted stock. The Plan has been amended at various times since its approval. The most recent amendment to the Plan, which was approved in March 2013 by the Company’s board of directors, increased the number of shares of common stock reserved for issuance to 7,875,000 shares, plus the number of shares of common stock subject to awards granted under the Company’s 2002 Incentive Plan which expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by us, up to a maximum of 625,000 shares. This amendment also adopted a fungible share pool whereby any award that is a full-value award (i.e. any restricted stock award, restricted stock unit award, or other stock-based award with a per share price or per unit purchase price lower than 100% of fair market value on the date of the grant) is counted against the share limits under the Plan as 1.5 shares for each one share of common stock subject to such full-value award.
	The Company has reserved 8,477,664 shares of common stock under the Plan, and at December 31, 2013, the Company has 5,362,977 shares available for future issuance under the Plan. Shares issued upon exercise of options are generally issued from new shares of the Company. The Plan provides that the exercise price of incentive stock options cannot be less than 100% of the fair market value of the common stock on the date of the award for participants who own less than 10% of the total combined voting power of stock of the Company and not less than 110% for participants who own more than 10% of the total combined voting power of the stock of the Company. Options and restricted stock granted under the Plan vest over periods as determined by the Board, which generally are equal to four years. Options generally expire ten years from the date of grant.
	Stock Incentive Plan—Employee Stock Options
	The fair value of each stock option granted is estimated on the date of grant using the Black-Scholes option-pricing model using the assumptions noted in the following table:
			Years Ended December 31,
			2013		2012	2011
	Volatility		64.22%-72.65%		64.30%-66.05%	64.37%-65.56%
	Expected Term (in years)		5.50-6.25		5.50-6.25	5.50-6.25
	Risk-Free Interest Rates		1.01%-2.10%		0.83%-1.33%	1.09%-2.57%
	Dividend Yield		—		—	—
	The risk-free interest rate is determined based upon the United States Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the options being valued. The Company does not expect to pay dividends in the foreseeable future.
	The Company does not have sufficient history to support a calculation of volatility and expected term using only its historical data. As such, the Company has used a weighted-average volatility considering the Company’s own volatility since March 2010, and the volatilities of several peer companies. For purposes of identifying similar entities, the Company considered characteristics such as industry, length of trading history, similar vesting terms and in-the-money option status. Due to lack of available option activity data, the Company elected to use the “simplified” method for “plain vanilla” options to estimate the expected term of the stock option grants. Under this approach, the weighted-average expected life is presumed to be the average of the vesting term and the contractual term of the option. Additionally, the Company is required to include an estimate of the value of the awards that will be forfeited in calculating compensation costs, which the Company estimates based upon actual historical forfeitures. The forfeiture estimates are recognized over the requisite service period of the awards on a straight-line basis. Based upon these assumptions, the weighted-average grant date fair value of stock options granted during the years ended December 31, 2013, 2012, and 2011 was $4.32, $7.40 and $9.55 per share, respectively.
	As of December 31, 2013, there was $3.1 million of total unrecognized stock-based compensation expense related to stock options granted under the Company’s 2002 Stock Incentive Plan and 2010 Stock Incentive Plan (collectively, the “Plans”). The expense is expected to be recognized over a weighted-average period of 1.8 years. The intrinsic value of options exercised was $0.5 million, $1.9 million and $6.5 million for the years ended December 31, 2013, 2012 and 2011, respectively.
	The following table summarizes the activity of the Plans for the year ended December 31, 2013:
			Number of			Weighted-		Weighted-		Aggregate
			Options			Average		Average		Intrinsic
						Exercise		Remaining		Value
						Price		Contractual
								Life
								(in years)
	Outstanding at December 31, 2012			4,638,388		$	9.86
	Granted			2,715,840		$	4.95
	Exercised			(185,311	)	$	1.46
	Forfeited			(1,860,918	)	$	8.81
	Expired			(1,011,305	)	$	10.8
	Outstanding at December 31, 2013			4,296,694		$	7.36		5.82	$	130,676
	Exercisable at December 31, 2013			2,676,724		$	8.53		4.14	$	130,676
	Vested or expected to vest at December 31, 2013			3,598,721		$	7.9		5.26	$	130,676
	Stock Incentive Plan—Nonemployee Stock Options
	During 2008, the Company granted nonqualified options to purchase 50,625 shares of common stock to nonemployee consultants, with an average exercise price of $6.84 per share. There were no stock options granted to nonemployee consultants during 2013, 2012 or 2011. The Company valued these options using the Black-Scholes option-pricing model and recognized expense related to these awards using the graded-vesting method. The unvested options held by consultants have been revalued using the Company’s estimate of fair value at each reporting period over the vesting period. The expense associated with these grants has been fully expensed as of December 31, 2012.
	Stock Incentive Plan—Restricted Stock
	The Company periodically grants awards of restricted stock to employees. These awards typically vest upon completion of the requisite service period or upon achievement of specified performance targets.
	The following table summarizes the restricted stock activity for the year ended December 31, 2013:
			Number of Shares			Weighted-
						Average
						Price
	Unvested at December 31, 2012			245,020		$	13.31
	Granted			689,678			5.23
	Cancelled			(660,698	)		8.79
	Expired			—			—
	Vested/Released			(32,500	)		14.16
	Unvested at December 31, 2013			241,500		$	2.5
	The fair value of restricted stock awards that vested was $0.5 million for the years ended December 31, 2013 and 2012. No shares vested during the year ended December 31, 2011. The Company reversed $2.0 million of previously recognized stock-based compensation expense during the year ended December 31, 2013 associated with performance-based restricted stock awards that are no longer probable of vesting. As of December 31, 2013, there was $0.1 million of total unrecognized stock-based compensation expense related to restricted stock awards granted under the Plan. The expense is expected to be recognized over a weighted-average period of 0.8 years if all performance targets are met.
	Employee Stock Purchase Plan
	In February 2010, the Board of Directors adopted the 2010 Employee Stock Purchase Plan (the “ESPP”) pursuant to which the Company may sell up to an aggregate of 250,000 shares of Common Stock. The ESPP was approved by the Company’s stockholders in February 2010. The plan was amended in March 2013 to increase the total number of shares available for the Company to sell to 764,000. The ESPP allows eligible employees to purchase common stock at a price per share equal to 85% of the lower of the fair market value of the common stock at the beginning or end of each six month period during the term of the ESPP. The first offering period began on July 1, 2010.
	Pursuant to the ESPP, the Company sold a total of 109,610 shares of common stock during the year ended December 31, 2013 at purchase prices of $2.13 and $1.56, respectively, which represent 85% of the closing price of the Company’s common stock on June 28, 2013 and December 31, 2013, respectively. For the year ended December 31, 2012, the Company sold a total of 94,592 shares of common stock at purchase prices of $10.34 and $6.84, respectively, which represent 85% of the closing price of the Company’s common stock on June 29, 2012 and December 31, 2012, respectively. For the year ended December 31, 2011, the Company sold a total of 57,187 shares of common stock at purchase prices of $12.64 and $14.62, respectively, which represent 85% of the closing price of the Company’s common stock on January 3, 2011 and December 30, 2011, respectively. The total stock-based compensation expense recorded as a result of the ESPP was approximately $0.2 million, $0.3 million and $0.3 million during the years ended December 31, 2013, 2012 and 2011, respectively.

Employee_Benefit_Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2013
Employee Benefit Plan	'
	12	Employee Benefit Plan
	In 2002, the Company established the AVEO Pharmaceuticals, Inc. 401(k) Plan (the “401(k) Plan”) for its employees, which is designed to be qualified under Section 401(k) of the Internal Revenue Code. Eligible employees are permitted to contribute to the 401(k) Plan within statutory and 401(k) Plan limits. The Company makes matching contributions of 50% of the first 5% of employee contributions. The Company made matching contributions of $0.4 million, $0.6 million, and $0.4 million for the years ended December 31, 2013, 2012 and 2011, respectively.

Strategic_Restructuring

Strategic Restructuring	12 Months Ended
	Dec. 31, 2013
Strategic Restructuring	'
	13	Strategic Restructuring
	In October 2012, the Company announced a strategic restructuring designed to optimize resources and reduce expenses. The Company’s restructuring and projected cost savings are being achieved through a combination of reduced spending on early stage research programs and a reduction in force of 48 positions, as well as the elimination of 30 previously open positions.
	In connection with the receipt of a Complete Response Letter from the FDA informing the Company that the FDA would not approve the Company’s NDA for tivozanib for the treatment of patients with advanced RCC, the Company announced a further strategic restructuring in June 2013 to refocus the Company’s efforts on the then on-going clinical development of tivozanib in colorectal and breast cancer and on the advancement of key pipeline and preclinical assets. As part of this restructuring, the Company decided not to pursue the development of tivozanib in RCC. This restructuring was completed as of December 31, 2013 and resulted in costs totaling $8.0 million. The total restructuring expense of $8.0 million for the year ended December 31, 2013 includes impairment charges of $0.3 million.
	The following table summarizes the components of the Company’s restructuring activity recorded in operating expenses and in accrued expenses in the accompanying consolidated balance sheet:
			Restructuring		Restructuring			Restructuring			Restructuring
			amounts accrued at		expense			amounts			amounts
			December 31,		incurred			paid			accrued at
			2012		during the year ended			during the year ended			December 31,
					December  31,			December  31,			2013
					2013			2013
			(in thousands)
	Employee severance, benefits and related costs.		$	1,653	$	7,674		$	(8,740	)	$	587
	Contract termination costs			—		82			(82	)		—
	Total			1,653		7,756			(8,822	)		587
			Restructuring		Restructuring			Restructuring
			expense		amounts			amounts
			incurred		paid			accrued at
			through		through			December 31,
			December 31,		December 31,			2012
			2012		2012
			(in thousands)
	Employee severance, benefits and related costs		$	2,633	$	(980	)	$	1,653
	The accrued restructuring amounts are current and reflected within accrued expenses on the consolidated balance sheet.

Quarterly_Results_Unaudited

Quarterly Results (Unaudited)	12 Months Ended
	Dec. 31, 2013
Quarterly Results (Unaudited)	'
	14	Quarterly Results (Unaudited)
			Three Months Ended
			March 31,			June 30,			September 30,			December 31,
			2013			2013			2013			2013
			(in thousands, except per share data)
			(unaudited)
	Collaboration revenue		$	323		$	324		$	323		$	323
	Restructuring			67			7,869			77			4
	Operating expenses			33,478			31,396			23,931			16,392
	Loss from operations			(33,155	)		(31,072	)		(23,608	)		(16,069	)
	Other expense, net			(930	)		(841	)		(698	)		(656	)
	Net loss		$	(34,085	)	$	(31,913	)	$	(24,306	)	$	(16,725	)
	Net loss per share—basic and diluted		$	(0.69	)	$	(0.62	)	$	(0.47	)	$	(0.32	)
			Three Months Ended
			March 31,			June 30,			September 30,			December 31,
			2012			2012			2012			2012
			(in thousands, except per share data)
			(unaudited)
	Collaboration revenue		$	860		$	1,877		$	1,018		$	15,531
	Restructuring			—			—			—			2,633
	Operating expenses			33,759			30,636			30,399			36,129
	Loss from operations			(32,899	)		(28,759	)		(29,381	)		(20,598	)
	Other expense, net			(347	)		(787	)		(741	)		(882	)
	Net loss		$	(33,246	)	$	(29,546	)	$	(30,122	)	$	(21,480	)
	Net loss per share—basic and diluted		$	(0.77	)	$	(0.68	)	$	(0.69	)	$	(0.49	)

Legal_Actions

Legal Actions	12 Months Ended
	Dec. 31, 2013
Legal Actions	'
	15	Legal Actions
	Two class action lawsuits have been filed against the Company and certain of the Company’s present and former officers and members of its board of directors, including Tuan Ha-Ngoc, David N. Johnston, William Slichenmyer and Ronald DePinho, in the United States District Court for the District of Massachusetts, one captioned Paul Sanders v. Aveo Pharmaceuticals, Inc., et al., No. 1:13-cv-11157-JLT, filed on May 9, 2013 and the other captioned Christine Krause v. AVEO Pharmaceuticals, Inc., et al., No. 1:13-cv-11320-JLT filed on May 31, 2013. On December 4, 2013, the District Court consolidated the complaints as In re AVEO Pharmaceuticals, Inc. Securities Litigation, No. 1:13-cv-11157-DJC, and an amended complaint was filed on February 3, 2014. The amended complaint purports to be brought on behalf of shareholders who purchased the Company’s common stock between January 3, 2012 and May 1, 2013. The amended complaint generally alleges that the Company and certain of the Company’s present and former officers and directors violated Sections 10(b) and/or 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder by making allegedly false and/or misleading statements concerning the phase 3 trial design and results for the Company’s TIVO-1 study in an effort to lead investors to believe that the drug would receive approval from the FDA. The amended complaint seeks unspecified damages, interest, attorneys’ fees, and other costs. The Company denies any allegations of wrongdoing and intends to vigorously defend against the lawsuit. However, there is no assurance that the Company will be successful in defense or that insurance will be available or adequate to fund any settlement or judgment or the litigation costs of the action. Moreover, the Company is unable to predict the outcome or reasonably estimate a range of possible loss at this time.
	On July 3, 2013, the Company received a subpoena from the SEC requesting documents and information concerning tivozanib, including related communications with the FDA, investors and others. The Company is fully cooperating with the SEC regarding this fact-finding inquiry. The SEC has informed the Company that this inquiry should not be construed as an indication that any violations of law have occurred or that the SEC has any negative opinion of any person, entity or security.
	Further discussion of additional legal matters that arose subsequent to the year ending December 31, 2013 is included in Footnote 16.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2013
Subsequent Events	'
	16	Subsequent Events
	In January 2014, the Company and Astellas jointly announced the decision to discontinue the Phase 2 breast cancer clinical study in patients with locally recurrent or metastatic triple negative breast cancer due to insufficient enrollment. In February 2014, AVEO and Astellas discontinued an ongoing Phase 2 study in patients with colorectal cancer. On February 12, 2014, Astellas elected to terminate the collaboration for tivozanib as a result of the limited scope of development for tivozanib moving forward. This termination will be effective August 2014, at which time the tivozanib rights will be returned to the Company. In accordance with the collaboration and license agreement, committed development costs, including the costs of winding down discontinued tivozanib clinical development programs, will be shared equally.
	The Company is aware of a potential plaintiff, a purported purchaser of the Company’s stock, seeking to file a derivative complaint allegedly on behalf of the Company in the United States District Court for the District of Massachusetts which would name the Company, as a nominal defendant and also would name as defendants present and former members of the Company’s board of directors, including Tuan Ha-Ngoc, Henri A. Termeer, Kenneth M. Bate, Anthony B. Evnin, Robert Epstein, Raju Kucherlapati, Robert C. Young, and Kenneth E. Weg. The complaint would allege breach of fiduciary duty and abuse of control between January 2012 and May 2013 with respect to allegedly misleading statements and omissions regarding tivozanib. The complaint would seek, among other relief, unspecified damages, costs and expenses, including attorneys’ fees, an order requiring the Company to implement certain corporate governance reforms, restitution from the defendants and such other relief as the court might find just and proper. The Company denies any allegations of wrongdoing and intends to vigorously defend this lawsuit, if filed. However, there is no assurance that the Company will be successful in its defense or that insurance will be available or adequate to fund any settlement or judgment or the litigation costs of this action. Moreover, the Company is unable to predict the outcome or reasonably estimate a range of possible loss at this time.

Significant_Accounting_Policie1

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Revenue Recognition	'
	Revenue Recognition
	The Company’s revenues are generated primarily through collaborative research, development and commercialization agreements. The terms of these agreements generally contain multiple elements, or deliverables, which may include (i) licenses, or options to obtain licenses, to the Company’s technology, (ii) research and development activities to be performed on behalf of the collaborative partner, and (iii) in certain cases, services in connection with the manufacturing of pre-clinical and clinical material. Payments to the Company under these arrangements typically include one or more of the following: non-refundable, up-front license fees; option exercise fees; funding of research and/or development efforts; milestone payments; and royalties on future product sales.
	When evaluating multiple element arrangements, the Company considers whether the deliverables under the arrangement represent separate units of accounting. This evaluation requires subjective determinations and requires management to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. In determining the units of accounting, management evaluates certain criteria, including whether the deliverables have standalone value, based on the relevant facts and circumstances for each arrangement. The consideration received is allocated among the separate units of accounting using the relative selling price method, and the applicable revenue recognition criteria are applied to each of the separate units.
	The Company determines the estimated selling price for deliverables within each agreement using vendor-specific objective evidence (“VSOE”) of selling price, if available, third-party evidence (“TPE”) of selling price if VSOE is not available, or best estimate of selling price if neither VSOE nor TPE is available. Determining the best estimate of selling price for a deliverable requires significant judgment. The Company typically uses best estimate of selling price to estimate the selling price for licenses to the Company’s proprietary technology, since the Company often does not have VSOE or TPE of selling price for these deliverables. In those circumstances where the Company utilizes best estimate of selling price to determine the estimated selling price of a license to the Company’s proprietary technology, the Company considers market conditions as well as entity-specific factors, including those factors contemplated in negotiating the agreements and internally developed models that include assumptions related to the market opportunity, estimated development costs, probability of success and the time needed to commercialize a product candidate pursuant to the license. In validating the Company’s best estimate of selling price, the Company evaluates whether changes in the key assumptions used to determine the best estimate of selling price will have a significant effect on the allocation of arrangement consideration among multiple deliverables.
	The Company typically receives non-refundable, up-front payments when licensing its intellectual property in conjunction with a research and development agreement. When management believes the license to its intellectual property does not have stand-alone value from the other deliverables to be provided in the arrangement, the Company generally recognizes revenue attributed to the license on a straight-line basis over the Company’s contractual or estimated performance period, which is typically the term of the Company’s research and development obligations. If management cannot reasonably estimate when the Company’s performance obligation ends, then revenue is deferred until management can reasonably estimate when the performance obligation ends. When management believes the license to its intellectual property has stand-alone value, the Company generally recognizes revenue attributed to the license upon delivery. The periods over which revenue should be recognized are subject to estimates by management and may change over the course of the research and development agreement. Such a change could have a material impact on the amount of revenue the Company records in future periods.
	Payments or reimbursements resulting from the Company’s research and development efforts for those arrangements where such efforts are considered as deliverables are recognized as the services are performed and are presented on a gross basis so long as there is persuasive evidence of an arrangement, the fee is fixed or determinable, and collection of the related receivable is reasonably assured. Amounts received prior to satisfying the above revenue recognition criteria are recorded as deferred revenue in the accompanying balance sheets.
	At the inception of each agreement that includes milestone payments, the Company evaluates whether each milestone is substantive and at risk to both parties on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether (a) the consideration is commensurate with either (1) the entity’s 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 the entity’s performance to achieve the milestone, (b) the consideration relates solely to past performance, and (c) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company evaluates factors such as the scientific, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required to achieve the respective milestone and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement in making this assessment.
	The Company aggregates its milestones into four categories: (i) clinical and development milestones, (ii) regulatory milestones, (iii) commercial milestones, and (iv) patent-related milestones. Clinical and development milestones are typically achieved when a product candidate advances into a defined phase of clinical research or completes such phase. For example, a milestone payment may be due to the Company upon the initiation of a phase 3 clinical trial for a new indication, which is the last phase of clinical development and could eventually contribute to marketing approval by the U.S. Food and Drug Administration (“FDA”) or other global regulatory authorities. Regulatory milestones are typically achieved upon acceptance of the submission for marketing approval of a product candidate or upon approval to market the product candidate by the FDA or other global regulatory authorities. For example, a milestone payment may be due to the Company upon the FDA’s acceptance of a New Drug Application (“NDA”). Commercial milestones are typically achieved when an approved pharmaceutical product reaches certain defined levels of net sales by the licensee, such as when a product first achieves global sales or annual sales of a specified amount. Patent-related milestones are typically achieved when a patent application is filed or a patent is issued with respect to certain intellectual property related to the applicable collaboration.
	Revenues from clinical and development, regulatory, and patent-related milestone payments, if the milestones are deemed substantive and the milestone payments are nonrefundable, are recognized upon successful accomplishment of the milestones. The Company has concluded that the clinical and development, regulatory and patent-related milestones pursuant to its current research and development arrangements are substantive. Milestones that are not considered substantive are accounted for as license payments and recognized on a straight-line basis over the remaining period of performance. Revenues from commercial milestone payments are accounted for as royalties and are recorded as revenue upon achievement of the milestone, assuming all other revenue recognition criteria are met.
Principles of Consolidation	'
	Principles of Consolidation
	The Company’s consolidated financial statements include the Company’s accounts and the accounts of the Company’s wholly-owned subsidiaries, AVEO Pharma Limited and AVEO Securities Corporation. All intercompany transactions have been eliminated.
Research and Development Expenses	'
	Research and Development Expenses
	Research and development expenses are charged to expense as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including personnel-related costs such as salaries and stock-based compensation, facilities, research-related overhead, clinical trial costs, manufacturing costs and costs of other contracted services, license fees, and other external costs. Nonrefundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received.
Cash and Cash Equivalents	'
	Cash and Cash Equivalents
	The Company considers highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash and cash equivalents at December 31, 2013 consisted of money market funds, asset-backed securities, asset-backed commercial paper, and corporate debt securities, including commercial paper, maintained by an investment manager. Cash and cash equivalents at December 31, 2012 consisted of a money market fund and corporate debt securities, including commercial paper, maintained by an investment manager.
Marketable Securities	'
	Marketable Securities
	Marketable securities at December 31, 2013 consisted of U.S. government agency securities, asset-backed securities, and corporate debt securities, including commercial paper, maintained by an investment manager. Marketable securities at December 31, 2012 consisted of municipal bonds, asset-backed commercial paper, asset-backed securities, and corporate debt securities, including commercial paper, maintained by an investment manager. Credit risk is reduced as a result of the Company’s policy to limit the amount invested in any one issue. Marketable securities consist primarily of investments which have expected average maturity dates in excess of three months, but not longer than 24 months. The Company classifies these investments as available-for-sale. Unrealized gains and losses are included in other comprehensive (loss) income until realized. The cost of securities sold is based on the specific identification method. The Company sold three securities during the year ended December 31, 2013 for gross proceeds of $10.3 million and did not recognize any gain or loss on the transactions. The Company sold one security during the year ended December 31, 2012 for gross proceeds of $2.7 million and recognized an immaterial gain. No securities were sold during the year ended December 31, 2011.
	Available-for-sale securities at December 31, 2013 and December 31, 2012 consist of the following:
			Amortized		Unrealized			Unrealized			Fair
			Cost		Gains			Losses			Value
			(in thousands)
	December 31, 2013:
	Corporate debt securities (Due within 1 year)		$	52,156	$	4		$	(4	)	$	52,156
	Government agency securities (Due within 1 year)			7,519		—			—			7,519
	Asset-backed securities (Due within 1 year)			8,007		—			(2	)		8,005
			$	67,682	$	4		$	(6	)	$	67,680
	December 31, 2012:
	Corporate debt securities (Due within 1 year)		$	58,751	$	16		$	(11	)	$	58,756
	Municipal bonds (Due within 1 year)			10,545		—			—			10,545
	Asset-backed securities (Due within 1 year)			6,359		—			—			6,359
	Asset-backed commercial paper (Due within 1 year)			8,806		2			—			8,808
			$	84,461	$	18		$	(11	)	$	84,468
	The aggregate fair value of securities in an unrealized loss position for less than 12 months at December 31, 2013 was $45.6 million, representing 18 securities. There were no securities that were in an unrealized loss position for greater than 12 months at December 31, 2013. The unrealized loss was caused by a temporary change in the market for those securities primarily caused by changes in market interest rates. There was no change in the credit risk of the securities. To determine whether an other-than-temporary impairment exists, the Company performs an analysis to assess whether it intends to sell, or whether it would more likely than not be required to sell, the security before the expected recovery of the amortized cost basis of the security. Where the Company intends to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary and the full amount of the unrealized loss is recorded in the statement of operations as an other-than-temporary impairment charge. When this is not the case, the Company performs additional analyses on all securities with unrealized losses to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where the Company does not expect to receive cash flows, based on using a single best estimate, sufficient to recover the amortized cost basis of a security and these recognized in other (expense) income, net. The Company does not believe an other-than-temporary impairment exists with respect to those securities in an unrealized loss position at December 31, 2013.
	Marketable securities in an unrealized loss position at December 31, 2013 and 2012 consist of the following:
			Aggregate		Unrealized
			Fair Value		Losses
			(in thousands)
	December 31, 2013:
	Corporate debt securities (Due within 1 year)		$	30,106	$	(4	)
	Government agency securities (Due within 1 year)			7,519		—
	Asset-backed securities (Due within 1 year)			8,005		(2	)
			$	45,630	$	(6	)
	December 31, 2012:
	Corporate debt securities (Due within 1 year)		$	29,806	$	(11	)
	Asset-backed securities (Due within 1 year)			6,359		—
			$	36,165	$	(11	)
Concentrations of Credit Risk	'
	Concentrations of Credit Risk
	Financial instruments that potentially subject the Company to credit risk primarily consist of cash, cash equivalents and marketable securities. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits.
	Management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held.
	The Company’s credit risk related to marketable securities is reduced as a result of the Company’s policy to limit the amount invested in any one issue.
Fair Value Measurements	'
	Fair Value Measurements
	The Company records cash equivalents and marketable securities at fair value. The accounting standards for fair value measurements establish a hierarchy that distinguishes between fair value measurements based on market data (observable inputs) and those based on the Company’s own assumptions (unobservable inputs). The hierarchy consists of three levels:
		•		Level 1—Quoted market prices in active markets for identical assets or liabilities. Assets that are valued utilizing only Level 1 inputs include money market funds.
		•		Level 2—Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves. Assets that are valued utilizing Level 2 inputs include U.S. government agency securities, asset-backed securities, and corporate bonds, including commercial paper. These investments have been initially valued at the transaction price and are subsequently valued, at the end of each reporting period, utilizing third party pricing services or other observable market data. The pricing services utilize industry standard valuation models, including both income and market based approaches and observable market inputs to determine value. These observable market inputs include reportable trades, benchmark yields, credit spreads, broker/dealer quotes, bids, offers, current spot rates, and other industry and economic events. The Company validates the prices provided by third party pricing services by reviewing their pricing methods and matrices, obtaining market values from other pricing sources, analyzing pricing data in certain instances and confirming that the relevant markets are active. After completing its validation procedures, the Company did not adjust or override any fair value measurements provided by pricing services as of December 31, 2013 or December 31, 2012.
		•		Level 3—Unobservable inputs developed using estimates and assumptions developed by the Company, which reflect those that a market participant would use. The Company currently has no assets or liabilities recorded at fair value that utilize Level 3 inputs.
	The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis in the accompanying consolidated balance sheets as of December 31, 2013 and 2012.
			Fair Value Measurements of Cash Equivalents and
			Marketable Securities as of December 31, 2013
			Level 1		Level 2			Level 3			Total
			(in thousands)
	Cash equivalents		$	29,865	$	15,958		$	—		$	45,823
	Marketable securities			—		67,680			—			67,680
			$	29,865	$	83,638		$	—		$	113,503
			Fair Value Measurements of Cash Equivalents and
			Marketable Securities as of December 31, 2012
			Level 1		Level 2			Level 3			Total
			(in thousands)
	Cash equivalents		$	51,182	$	18,121		$	—		$	69,303
	Marketable securities			—		84,468			—			84,468
			$	51,182	$	102,589		$	—		$	153,771
	The fair value of the Company’s loans payable at December 31, 2013 and 2012, computed pursuant to a discounted cash flow technique using the effective interest rate under the loan, was $20.1 million and $26.4 million, respectively. These fair values are considered a level 2 fair value measurement. The effective interest rate considers the fair value of the warrant issued in connection with the loan, loan issuance costs and a deferred charge, which approximates a market interest rate. The fair value of the Company’s term loan payable is determined using current applicable rates for similar instruments as of the balance sheet date.
Property and Equipment	'
	Property and Equipment
	Property and equipment are stated at cost and are depreciated using the straight-line method over the estimated useful lives of the respective assets. Maintenance and repair costs are charged to expense as incurred.
Long-lived Assets	'
	Long-lived Assets
	The Company reviews long-lived assets, including property and equipment, for impairment whenever changes in business circumstances indicate that the carrying amount of the asset may not be fully recoverable. During the year ended December 31, 2013, the Company recognized $0.1 million of impairment losses. No impairment losses were recognized during the years ended December 31, 2012 or 2011.
Stock-Based Compensation	'
	Stock-Based Compensation
	Under the Company’s stock-based compensation programs, the Company periodically grants stock options and restricted stock to employees, directors and nonemployee consultants. The Company also issues shares under an employee stock purchase plan. The fair value of all awards is recognized in the Company’s statements of operations over the requisite service period for each award. Awards that vest as the recipient provides service are expensed on a straight-line basis over the requisite service period. Other awards, such as performance-based awards that vest upon the achievement of specified goals, are expensed using the accelerated attribution method if achievement of the specified goals is considered probable.
	The fair value of equity-classified awards to employees and directors are measured on the date the awards are granted. During the years ended December 31, 2013, 2012 and 2011, the Company recorded the following stock-based compensation expense for equity-classified awards:
			Years Ended December 31,
			2013		2012			2011
			(in thousands)
	Research and development		$	1,991	$	3,566		$	2,504
	General and administrative			1,800		4,380			3,399
	Restructuring			—		61			—
	Total stock-based compensation expense		$	3,791	$	8,007		$	5,903
	Liability-classified awards to employees and directors are re-measured to the award’s fair value as of each balance sheet date until the award is settled. The Company recorded $0.1 million in compensation expense for liability-classified awards during the year ending December 31, 2013. No costs associated with liability-classified awards were recognized during the years ended December 31, 2012 or 2011.
	Awards to nonemployee consultants are recorded at their fair values and re-measured to the award’s fair value as of each balance sheet date until the recipient’s services are complete.
	Stock-based compensation expense is allocated to research and development and general and administrative expense based upon the department of the employee to whom each award was granted. No related tax benefits of the stock-based compensation expense have been recognized.
Income Taxes	'
	Income Taxes
	The Company provides for income taxes using the asset-liability method. Under this method, deferred tax assets and liabilities are recognized based on differences between financial reporting and tax bases of assets and liabilities, and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Uncertain tax positions are recognized if the position is more-likely-than-not to be sustained upon examination by a tax authority. Unrecognized tax benefits represent tax positions for which reserves have been established.
Segment and Geographic Information	'
	Segment and Geographic Information
	Operating segments are defined as components of an enterprise engaging in business activities for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment principally in the United States. The Company has $1.0 million of net assets located in the United Kingdom.
Use of Estimates	'
	Use of Estimates
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States (“GAAP”) requires the Company’s management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Reclassifications	'
	Reclassifications
	The Company has reclassified the tenant improvement allowance receivable from prepaid expenses and other current assets on the consolidated balance sheets to a separate financial statement line to conform to the current period presentation.

Significant_Accounting_Policie2

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2013
Available-For-Sale Securities	'
	Available-for-sale securities at December 31, 2013 and December 31, 2012 consist of the following:
		Amortized		Unrealized			Unrealized			Fair
		Cost		Gains			Losses			Value
		(in thousands)
	December 31, 2013:
	Corporate debt securities (Due within 1 year)	$	52,156	$	4		$	(4	)	$	52,156
	Government agency securities (Due within 1 year)		7,519		—			—			7,519
	Asset-backed securities (Due within 1 year)		8,007		—			(2	)		8,005
		$	67,682	$	4		$	(6	)	$	67,680
	December 31, 2012:
	Corporate debt securities (Due within 1 year)	$	58,751	$	16		$	(11	)	$	58,756
	Municipal bonds (Due within 1 year)		10,545		—			—			10,545
	Asset-backed securities (Due within 1 year)		6,359		—			—			6,359
	Asset-backed commercial paper (Due within 1 year)		8,806		2			—			8,808
		$	84,461	$	18		$	(11	)	$	84,468
Marketable Securities in Unrealized Loss Position	'
	Marketable securities in an unrealized loss position at December 31, 2013 and 2012 consist of the following:
		Aggregate		Unrealized
		Fair Value		Losses
		(in thousands)
	December 31, 2013:
	Corporate debt securities (Due within 1 year)	$	30,106	$	(4	)
	Government agency securities (Due within 1 year)		7,519		—
	Asset-backed securities (Due within 1 year)		8,005		(2	)
		$	45,630	$	(6	)
	December 31, 2012:
	Corporate debt securities (Due within 1 year)	$	29,806	$	(11	)
	Asset-backed securities (Due within 1 year)		6,359		—
		$	36,165	$	(11	)
Summary of Cash Equivalents and Marketable Securities Measured at Fair Value on Recurring Basis	'
	The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis in the accompanying consolidated balance sheets as of December 31, 2013 and 2012.
		Fair Value Measurements of Cash Equivalents and
		Marketable Securities as of December 31, 2013
		Level 1		Level 2			Level 3			Total
		(in thousands)
	Cash equivalents	$	29,865	$	15,958		$	—		$	45,823
	Marketable securities		—		67,680			—			67,680
		$	29,865	$	83,638		$	—		$	113,503
		Fair Value Measurements of Cash Equivalents and
		Marketable Securities as of December 31, 2012
		Level 1		Level 2			Level 3			Total
		(in thousands)
	Cash equivalents	$	51,182	$	18,121		$	—		$	69,303
	Marketable securities		—		84,468			—			84,468
		$	51,182	$	102,589		$	—		$	153,771
Equity-classified awards	'
Stock-Based Compensation Expense for Equity-Classified Awards	'
	During the years ended December 31, 2013, 2012 and 2011, the Company recorded the following stock-based compensation expense for equity-classified awards:
		Years Ended December 31,
		2013		2012			2011
		(in thousands)
	Research and development	$	1,991	$	3,566		$	2,504
	General and administrative		1,800		4,380			3,399
	Restructuring		—		61			—
	Total stock-based compensation expense	$	3,791	$	8,007		$	5,903

Loss_Earnings_Per_Common_Share1

(Loss) Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2013
Basic and Diluted Earnings Per Share	'
	Basic and diluted (loss) earnings per share for the years ended December 31, 2013, 2012 and 2011 are as follows:
		Years Ended December 31,
		2013			2012			2011
		(in thousands, except per share amounts)
	Basic (loss) earnings per share
	Net (loss) income	$	(107,029	)	$	(114,394	)	$	30,648
	Income allocated to participating securities		—			—			(46	)
	(Loss) income available to common stockholders		(107,029	)		(114,394	)		30,602
	Basic weighted average common shares outstanding		50,928			43,374			39,715
	Basic (loss) earnings per share	$	(2.10	)	$	(2.64	)	$	0.77
	Diluted (loss) earnings per share
	Net (loss) income	$	(107,029	)	$	(114,394	)	$	30,648
	Income allocated to participating securities		—			—			(45	)
	(Loss) income available to common stockholders		(107,029	)		(114,394	)		30,603
	Weighted average common shares outstanding		50,928			43,374			39,715
	Diluted potential common shares		—			—			1,758
	Diluted weighted average common shares and potential common shares		50,928			43,374			41,473
	Diluted (loss) earnings per share	$	(2.10	)	$	(2.64	)	$	0.74
Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss or Earnings Per Share	'
	The following potentially dilutive securities were excluded from the calculation of diluted net (loss) earnings per share due to their anti-dilutive effect:
		Years Ended December 31,
		2013			2012			2011
		(in thousands)
	Outstanding stock options		4,297			4,638			276
	Unvested restricted stock		242			245			—

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2013
Property and Equipment	'
	Property and equipment consists of the following:
		Estimated	December 31,			December 31,
		Useful Life	2013			2012
			(in thousands)
	Laboratory equipment	5 years	$	8,660		$	9,299
	Computer equipment and software	3 years		4,398			3,480
	Office furniture	5 years		930			579
	Leasehold improvements	Shorter of asset’s useful life		11,959			5,090
		or remaining term of lease
	Construction in process	—		3,193			6,956
				29,140			25,404
	Less accumulated depreciation and amortization			(15,000	)		(12,537	)
	Property and equipment, net		$	14,140		$	12,867

Accrued_Expenses_Tables

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2013
Accrued Expenses	'
	Accrued expenses consisted of the following:
		December 31,		December 31,
		2013		2012
		(in thousands)
	Clinical expenses	$	5,319	$	6,688
	Salaries and benefits		2,027		6,015
	Property and equipment		1,905		377
	Manufacturing and distribution		1,362		670
	Professional fees		811		430
	Restructuring		587		1,653
	Collaboration expenses		—		1,807
	Pre-commercialization expenses		—		924
	Other		1,252		979
		$	13,263	$	19,543

Loans_Payable_Tables

Loans Payable (Tables)	12 Months Ended
	Dec. 31, 2013
Future Minimum Payments Under Loans Payable	'
	Future minimum payments under the loans payable outstanding as of December 31, 2013 are as follows (amounts in thousands):
	Years Ending December 31:
	2014		13,547
	2015		9,309
			22,856
	Less amount representing interest		(2,221	)
	Less discount		(192	)
	Less deferred charges		(1,238	)
	Less current portion		(10,383	)
	Loans payable, net of current portion	$	8,822

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2013
Future Annual Minimum Lease Payments	'
	Future annual minimum lease payments under all noncancelable operating leases at December 31, 2013 are as follows (amounts in thousands):
	Years Ending December 31:
	2014		8,077
	2015		7,530
	2016		7,508
	2017		7,733
	2018 and thereafter		61,030
		$	91,878

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Reconciliation of Expected Income Tax Benefit	'
	A reconciliation of the expected income tax benefit computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows for the years ended December 31, 2013, 2012 and 2011:
		December 31,			December 31,			December 31,
		2013			2012			2011
	Income tax computed at federal statutory tax rate		34	%		34	%		34	%
	State taxes, net of federal benefit		5.1	%		5.1	%		5.3	%
	Research and development credits		2	%		0.1	%		(5.1	)%
	Permanent differences		(0.9	)%		(1.2	)%		2.8	%
	Foreign rate differential		(0.2	)%		(0.4	)%		0	%
	Other		(0.5	)%		(0.2	)%		0.3	%
	Change in valuation allowance		(39.5	)%		(37.4	)%		(37.3	)%
	Total		0	%		0	%		0	%
Company Net Deferred Tax Assets	'
	The Company’s net deferred tax assets as of December 31, 2013 and 2012 are as follows:
		2013			2012
		(in thousands)
	NOL carryforwards	$	134,023		$	99,001
	Research and development credits		11,357			7,960
	Deferred revenue		7,224			7,732
	Other temporary differences		15,158			10,776
	Valuation allowance		(167,762	)		(125,469	)
		$	—		$	—
Reconciliation of Gross Uncertain Tax Positions	'
	The following is a reconciliation of the Company’s gross uncertain tax positions at December 31, 2013 and 2012:
		Year ended			Year ended
		December 31,			December 31,
		2013			2012
		(in thousands)
	Amount established upon adoption	$	1,200		$	1,200
	Additions for current year tax positions		—			—
	Additions for prior year tax positions		—			—
	Reductions of prior year tax positions		—			—
	Balance as of end of year	$	1,200		$	1,200

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2013
Assumptions used in Black-Scholes Pricing Model for New Grants	'
	The fair value of each stock option granted is estimated on the date of grant using the Black-Scholes option-pricing model using the assumptions noted in the following table:
		Years Ended December 31,
		2013		2012	2011
	Volatility	64.22%-72.65%		64.30%-66.05%	64.37%-65.56%
	Expected Term (in years)	5.50-6.25		5.50-6.25	5.50-6.25
	Risk-Free Interest Rates	1.01%-2.10%		0.83%-1.33%	1.09%-2.57%
	Dividend Yield	—		—	—
Stock Option Activity	'
	The following table summarizes the activity of the Plans for the year ended December 31, 2013:
		Number of			Weighted-		Weighted-		Aggregate
		Options			Average		Average		Intrinsic
					Exercise		Remaining		Value
					Price		Contractual
							Life
							(in years)
	Outstanding at December 31, 2012		4,638,388		$	9.86
	Granted		2,715,840		$	4.95
	Exercised		(185,311	)	$	1.46
	Forfeited		(1,860,918	)	$	8.81
	Expired		(1,011,305	)	$	10.8
	Outstanding at December 31, 2013		4,296,694		$	7.36		5.82	$	130,676
	Exercisable at December 31, 2013		2,676,724		$	8.53		4.14	$	130,676
	Vested or expected to vest at December 31, 2013		3,598,721		$	7.9		5.26	$	130,676
Restricted Stock Activity	'
	The following table summarizes the restricted stock activity for the year ended December 31, 2013:
		Number of Shares			Weighted-
					Average
					Price
	Unvested at December 31, 2012		245,020		$	13.31
	Granted		689,678			5.23
	Cancelled		(660,698	)		8.79
	Expired		—			—
	Vested/Released		(32,500	)		14.16
	Unvested at December 31, 2013		241,500		$	2.5

Strategic_Restructuring_Tables

Strategic Restructuring (Tables)	12 Months Ended
	Dec. 31, 2013
Restructuring Activity Recorded in Operating Expenses and in Accrued Expenses	'
	The following table summarizes the components of the Company’s restructuring activity recorded in operating expenses and in accrued expenses in the accompanying consolidated balance sheet:
		Restructuring		Restructuring			Restructuring			Restructuring
		amounts accrued at		expense			amounts			amounts
		December 31,		incurred			paid			accrued at
		2012		during the year ended			during the year ended			December 31,
				December  31,			December  31,			2013
				2013			2013
		(in thousands)
	Employee severance, benefits and related costs.	$	1,653	$	7,674		$	(8,740	)	$	587
	Contract termination costs		—		82			(82	)		—
	Total		1,653		7,756			(8,822	)		587
		Restructuring		Restructuring			Restructuring
		expense		amounts			amounts
		incurred		paid			accrued at
		through		through			December 31,
		December 31,		December 31,			2012
		2012		2012
		(in thousands)
	Employee severance, benefits and related costs	$	2,633	$	(980	)	$	1,653

Quarterly_Results_Unaudited_Ta

Quarterly Results (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2013
Summary of Quarterly Results	'
		Three Months Ended
		March 31,			June 30,			September 30,			December 31,
		2013			2013			2013			2013
		(in thousands, except per share data)
		(unaudited)
	Collaboration revenue	$	323		$	324		$	323		$	323
	Restructuring		67			7,869			77			4
	Operating expenses		33,478			31,396			23,931			16,392
	Loss from operations		(33,155	)		(31,072	)		(23,608	)		(16,069	)
	Other expense, net		(930	)		(841	)		(698	)		(656	)
	Net loss	$	(34,085	)	$	(31,913	)	$	(24,306	)	$	(16,725	)
	Net loss per share—basic and diluted	$	(0.69	)	$	(0.62	)	$	(0.47	)	$	(0.32	)
		Three Months Ended
		March 31,			June 30,			September 30,			December 31,
		2012			2012			2012			2012
		(in thousands, except per share data)
		(unaudited)
	Collaboration revenue	$	860		$	1,877		$	1,018		$	15,531
	Restructuring		—			—			—			2,633
	Operating expenses		33,759			30,636			30,399			36,129
	Loss from operations		(32,899	)		(28,759	)		(29,381	)		(20,598	)
	Other expense, net		(347	)		(787	)		(741	)		(882	)
	Net loss	$	(33,246	)	$	(29,546	)	$	(30,122	)	$	(21,480	)
	Net loss per share—basic and diluted	$	(0.77	)	$	(0.68	)	$	(0.69	)	$	(0.49	)

Nature_of_Business_and_Organiz1

Nature of Business and Organization - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Nature Of Business [Line Items]	'	'
Accumulated deficit	($427,289)	($320,260)

Significant_Accounting_Policie3

Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Segment	Securities	Securities
	Securities
Significant Accounting Policies [Line Items]	'	'	'
Proceeds from maturities and sales of marketable securities	$191,129,000	$339,779,000	$234,795,000
Gain (loss) recognized on sale security	0	'	'
Number of securities sold	3	1	0
Available for sale securities, aggregate fair value of securities in an unrealized loss position for less than 12 months	45,600,000	'	'
Impairment losses	100,000	0	0
Number of operating segments	1	'	'
Liability Classified Awards	'	'	'
Significant Accounting Policies [Line Items]	'	'	'
Stock-based compensation expense	100,000	0	0
United Kingdom	'	'	'
Significant Accounting Policies [Line Items]	'	'	'
Net assets located in the United Kingdom	1,000,000	'	'
Available For Sale Securities, Continuous Unrealized Loss Positions, Less Than 12 Months	'	'	'
Significant Accounting Policies [Line Items]	'	'	'
Available for sale securities, number of securities in an unrealized loss position	18	'	'
Available For Sale Securities, Continuous Unrealized Loss Positions, Greater Than 12 Months	'	'	'
Significant Accounting Policies [Line Items]	'	'	'
Available for sale securities, aggregate fair value of securities	0	'	'
Level 2	'	'	'
Significant Accounting Policies [Line Items]	'	'	'
Fair value of loan payable	20,100,000	26,400,000	'
1 Security Sold	'	'	'
Significant Accounting Policies [Line Items]	'	'	'
Proceeds from maturities and sales of marketable securities	$10,300,000	$2,700,000	'
Minimum	'	'	'
Significant Accounting Policies [Line Items]	'	'	'
Marketable securities maturity term	'3 months	'	'
Maximum	'	'	'
Significant Accounting Policies [Line Items]	'	'	'
Marketable securities maturity term	'24 months	'	'

Available_for_Sale_Securities_

Available for Sale Securities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$67,682	$84,461
Unrealized Gains	4	18
Unrealized Losses	-6	-11
Fair Value	67,680	84,468
Corporate debt securities | Due within 1 year	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	52,156	58,751
Unrealized Gains	4	16
Unrealized Losses	-4	-11
Fair Value	52,156	58,756
Government agency securities | Due within 1 year	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	7,519	'
Fair Value	7,519	'
Asset-backed Securities | Due within 1 year	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	8,007	6,359
Unrealized Losses	-2	'
Fair Value	8,005	6,359
Asset-backed Commercial Paper | Due within 1 year	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	'	8,806
Unrealized Gains	'	2
Fair Value	'	8,808
Municipal Bonds | Due within 1 year	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	'	10,545
Fair Value	'	$10,545

Marketable_Securities_in_Unrea

Marketable Securities in Unrealized Loss Position (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Investments, Unrealized Loss Position [Line Items]	'	'
Aggregate Fair Value	$45,630	$36,165
Unrealized Losses	-6	-11
Corporate debt securities | Due within 1 year	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Aggregate Fair Value	30,106	29,806
Unrealized Losses	-4	-11
Government agency securities | Due within 1 year	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Aggregate Fair Value	7,519	'
Asset-backed Securities | Due within 1 year	'	'
Investments, Unrealized Loss Position [Line Items]	'	'
Aggregate Fair Value	8,005	6,359
Unrealized Losses	($2)	'

Summary_of_Cash_Equivalents_an

Summary of Cash Equivalents and Marketable Securities Measured at Fair Value on Recurring Basis (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Marketable securities	$67,680	$84,468
Fair Value, Measurements, Recurring	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash equivalents	45,823	69,303
Marketable securities	67,680	84,468
Cash Equivalents, and Marketable Securities Fair Value Disclosure, Total	113,503	153,771
Fair Value, Measurements, Recurring | Level 1	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash equivalents	29,865	51,182
Cash Equivalents, and Marketable Securities Fair Value Disclosure, Total	29,865	51,182
Fair Value, Measurements, Recurring | Level 2	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash equivalents	15,958	18,121
Marketable securities	67,680	84,468
Cash Equivalents, and Marketable Securities Fair Value Disclosure, Total	$83,638	$102,589

Stock_Based_Compensation_Expen

Stock Based Compensation Expense for Equity-Classified Awards (Detail) (Equity-classified awards, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation expense	$3,791	$8,007	$5,903
Research and development	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation expense	1,991	3,566	2,504
General and administrative	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation expense	1,800	4,380	3,399
Restructuring Charges	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'
Stock-based compensation expense	'	$61	'

Basic_and_Diluted_Earnings_Per

Basic and Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Basic (loss) earnings per share	'	'	'	'	'	'	'	'	'	'	'
Net (loss) income	($16,725)	($24,306)	($31,913)	($34,085)	($21,480)	($30,122)	($29,546)	($33,246)	($107,029)	($114,394)	$30,648
Income allocated to participating securities	'	'	'	'	'	'	'	'	'	'	-46
(Loss) income available to common stockholders	'	'	'	'	'	'	'	'	-107,029	-114,394	30,602
Basic weighted average common shares outstanding	'	'	'	'	'	'	'	'	50,928	43,374	39,715
Basic (loss) earnings per share	'	'	'	'	'	'	'	'	($2.10)	($2.64)	$0.77
Diluted (loss) earnings per share	'	'	'	'	'	'	'	'	'	'	'
Net (loss) income	-16,725	-24,306	-31,913	-34,085	-21,480	-30,122	-29,546	-33,246	-107,029	-114,394	30,648
Income allocated to participating securities	'	'	'	'	'	'	'	'	'	'	-45
(Loss) income available to common stockholders	'	'	'	'	'	'	'	'	($107,029)	($114,394)	$30,603
Weighted average common shares outstanding	'	'	'	'	'	'	'	'	50,928	43,374	39,715
Diluted potential common shares	'	'	'	'	'	'	'	'	'	'	1,758
Diluted weighted average common shares and potential common shares	'	'	'	'	'	'	'	'	50,928	43,374	41,473
Diluted (loss) earnings per share	'	'	'	'	'	'	'	'	($2.10)	($2.64)	$0.74

Potentially_Dilutive_Securitie

Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss or Earnings Per Share (Detail)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Option	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'
Antidilutive securities excluded from computation of earnings per share	4,297	4,638	276
Restricted Stock	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'
Antidilutive securities excluded from computation of earnings per share	242	245	'

Property_and_Equipment_Detail

Property and Equipment (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]	'	'
Property, Plant, And Equipment, Gross	$29,140	$25,404
Less accumulated depreciation and amortization	-15,000	-12,537
Property and equipment, net	14,140	12,867
Laboratory Equipment	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, estimated useful life	'5 years	'
Property, Plant, And Equipment, Gross	8,660	9,299
Computers Equipment And Software	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, estimated useful life	'3 years	'
Property, Plant, And Equipment, Gross	4,398	3,480
Furniture and Fixtures	'	'
Property, Plant and Equipment [Line Items]	'	'
Property and equipment, estimated useful life	'5 years	'
Property, Plant, And Equipment, Gross	930	579
Leasehold Improvements	'	'
Property, Plant and Equipment [Line Items]	'	'
Leasehold improvements	'Shorter of asset's useful life or remaining term of lease	'
Property, Plant, And Equipment, Gross	11,959	5,090
Construction in Progress	'	'
Property, Plant and Equipment [Line Items]	'	'
Property, Plant, And Equipment, Gross	$3,193	$6,956

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]	'	'	'
Depreciation expense	$3,775	$2,510	$1,654

Accrued_Expenses_Detail

Accrued Expenses (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Accrued Liabilities [Line Items]	'	'
Clinical expenses	$5,319	$6,688
Salaries and benefits	2,027	6,015
Property and equipment	1,905	377
Manufacturing and distribution	1,362	670
Professional fees	811	430
Restructuring	587	1,653
Collaboration expenses	'	1,807
Pre-commercialization expenses	'	924
Other	1,252	979
Accrued expenses	$13,263	$19,543

Loans_Payable_Additional_Infor

Loans Payable - Additional Information (Detail) (USD $)	1 Months Ended			12 Months Ended
	Mar. 31, 2012	Jun. 30, 2010	31-May-10	Dec. 31, 2013	Jun. 02, 2010
	Installment		Installment		Y
Debt Instrument [Line Items]	'	'	'	'	'
Loan payable, aggregate principal amount	$26,500,000	'	$25,000,000	'	'
Loan payable, number of installments of principal	30	'	30	'	'
Loan payable, start date of first principal payment	31-Mar-13	'	1-Apr-11	'	'
Loan payable, description of interest rate terms	'	'	'Per annum interest on the principal balance of the loan is payable at the greater of 11.9% and an amount equal to 11.9% plus the prime rate of interest minus 4.75%,	'	'
Loan payable, interest rate, base rate	'	'	11.90%	'	'
Loan payable, interest rate, additional rate deducted from base rate	'	'	4.75%	'	'
Loan payable, maximum per annum interest rate	'	'	15.00%	'	'
Loan payable, due date	'	'	1-Sep-15	'	'
Deferred charge related to loan	1,250,000	'	'	1,238,000	'
Loan issuance costs paid	'	'	200,000	'	'
Warrants issued to lenders as part of the new loan agreement, shares of common stock to purchase	'	'	'	'	156,641
Warrants issued to lenders as part of the new loan agreement, exercise price	'	'	'	'	7.98
Warrants issued to lenders as part of the new loan agreement, expiration period (in years)	'	'	'	'	'7 years
Warrants issued to lenders as part of the new loan agreement, fair value	'	800,000	'	'	'
Assumptions used in the Black-Scholes pricing model for warrant, volatility	'	'	'	'	64.12%
Assumptions used in the Black-Scholes pricing model for warrant, expected term	'	'	'	'	7
Assumptions used in the Black-Scholes pricing model for warrant, risk-free interest rate	'	'	'	'	2.81%
Loan payable, effective interest rate	'	'	'	13.10%	'
Option to purchase equity, description	'	'	'	'Hercules also received an option, subject to the Company's written consent, not to be unreasonably withheld, to purchase, either with cash or through conversion of outstanding principal under the loan, up to $2.0 million of equity of the Company sold in any sale by the Company to third parties of equity securities resulting in at least $10.0 million in net cash proceeds to the Company, subject to certain exceptions.	'
Option to purchase equity, maximum amount	'	'	'	2,000,000	'
Loan outstanding	'	'	'	19,400,000	'
Minimum	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'
Loan payable, interest rate	'	'	11.90%	'	'
Option to purchase equity, net cash proceeds of equity securities	'	'	'	$10,000,000	'

Future_Minimum_Payments_Under_

Future Minimum Payments Under Loans Payable (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'	'
2014	$13,547	'
2015	9,309	'
Long-term Debt, Gross, Total	22,856	'
Less amount representing interest	-2,221	'
Less discount	-192	'
Less deferred charges	-1,238	'
Less current portion Loans Payable Current	-10,383	-6,809
Loans payable, net of current portion	$8,822	$19,228

Collaborations_and_License_Agr

Collaborations and License Agreements - Additional Information (Detail) (USD $)

3 Months Ended

12 Months Ended

12 Months Ended

1 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

3 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

9 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

10 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

1 Months Ended

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Feb. 28, 2011

Mar. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Mar. 31, 2011

Dec. 31, 2012

Feb. 28, 2011

Feb. 28, 2011

Mar. 31, 2011

Jul. 31, 2009

Jul. 31, 2009

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Sep. 30, 2008

Sep. 30, 2007

Apr. 30, 2007

Jul. 31, 2009

Jul. 31, 2009

Jul. 31, 2009

Jul. 31, 2009

Dec. 31, 2013

Jul. 31, 2011

Nov. 30, 2010

Jul. 31, 2011

Jul. 31, 2009

Sep. 30, 2007

Jul. 31, 2009

Sep. 30, 2007

Jul. 31, 2009

31-May-12

31-May-12

31-May-11

Dec. 31, 2012

Dec. 31, 2011

31-May-11

31-May-11

Jun. 30, 2011

31-May-11

31-May-11

Mar. 31, 2011

Dec. 31, 2012

Dec. 31, 2013

Mar. 31, 2010

Dec. 31, 2006

Dec. 31, 2011

Dec. 31, 2006

Dec. 31, 2006

Dec. 31, 2006

Jul. 30, 2011

Mar. 31, 2010

Jun. 30, 2009

Mar. 31, 2009

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 31, 2009

Mar. 31, 2009

Mar. 31, 2009

Mar. 31, 2009

Mar. 31, 2009

Jul. 31, 2012

Jul. 31, 2012

Jul. 31, 2012

Jul. 31, 2012

Other License Agreements

Other License Agreements

Other License Agreements

Other License Agreements

Other License Agreements

Scenario 1

Scenario 2

Scenario 3

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

Astellas Pharma Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

OSI Pharmaceuticals, Inc.

Centocor Ortho Biotech Inc.

Centocor Ortho Biotech Inc.

Centocor Ortho Biotech Inc.

Centocor Ortho Biotech Inc.

Centocor Ortho Biotech Inc.

Centocor Ortho Biotech Inc.

Centocor Ortho Biotech Inc.

Centocor Ortho Biotech Inc.

Schering-Plough Corporation (now Merck)

Kirin Brewery Co. Ltd.

Kirin Brewery Co. Ltd.

Kirin Brewery Co. Ltd.

Kirin Brewery Co. Ltd.

Kirin Brewery Co. Ltd.

Kirin Brewery Co. Ltd.

Kirin Brewery Co. Ltd.

Kirin Brewery Co. Ltd.

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

Biogen Idec International GmbH

St Vincent's Hospital Sydney Limited

St Vincent's Hospital Sydney Limited

St Vincent's Hospital Sydney Limited

St Vincent's Hospital Sydney Limited

Minimum

Maximum

Collaboration and License Agreement

Collaboration and License Agreement

Collaboration and License Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

Collaborative Arrangements, Co-promotion Agreement, Agreement

July 2009 expanded agreement

July 2009 expanded agreement

July 2009 expanded agreement

Collaboration and License Agreement

Collaboration and License Agreement

Collaboration and License Agreement

Collaboration and License Agreement

Collaboration and License Agreement

Collaboration and License Agreement

Substantive Milestones

Regulatory Milestone Events

Sales Events Milestone

Biomarker Related Milestones

Biomarker Related Milestones

Option Exercise

Option Exercise

Option Exercise

Up-front Payment Arrangement

Up-front Payment Arrangement

Premium on Sale of Stock

Premium on Sale of Stock

Quarterly Payment

Patent related milestone

Clinical and development milestone

Licensing Agreements

License Deliverable

License Deliverable

Up-front Payment Arrangement

Up-front Payment Arrangement

Collaboration and License Agreement

Collaboration and License Agreement

Licensing Agreements

Licensing Agreements

Licensing Agreements

FDA Marketing Approval

EMA Marketing Authorization

Ema Marketing Approval

Option and License Agreement

Option and License Agreement

Option and License Agreement

Option and License Agreement

Option and License Agreement

Option and License Agreement

Option and License Agreement

Option and License Agreement

Option Exercise

Up-front Payment Arrangement

Premium on Sale of Stock

First Regulatory Milestone

Licensing Agreements

Up-front Payment Arrangement

MIC-1 research and development programs

Licensed Patents

Research and development

Research and development

Research and development

General and administrative

General and administrative

General and administrative

License Deliverable

License Deliverable

Royalty Territory Deliverable

Royalty Territory Deliverable

Royalty Territory Deliverable

Regulatory Milestone Events

Up-front Payment Arrangement

research and development funding

Minimum

Series E Convertible Preferred Stock

Research Program Funding

Series C Convertible Preferred Stock

Series C Convertible Preferred Stock

July 2009 expanded agreement

July 2009 expanded agreement

July 2009 expanded agreement

July 2009 expanded agreement

July 2009 expanded agreement

July 2009 expanded agreement

July 2009 expanded agreement

July 2009 expanded agreement

July 2009 expanded agreement

Collaboration and License Agreement

July 2009 expanded agreement

Collaboration and License Agreement

Collaboration and License Agreement

Collaboration and License Agreement

Collaboration and License Agreement

Common Stock

Licensing Agreements

Licensing Agreements

Licensing Agreements

Licensing Agreements

Licensing Agreements

Licensing Agreements

Licensing Agreements

Series E Convertible Preferred Stock

Option and License Agreement

Option and License Agreement

Option and License Agreement

Option and License Agreement

Licensing Agreements

Licensing Agreements

Licensing Agreements

Series E Convertible Preferred Stock

Series C Convertible Preferred Stock

Research Program Funding

Common Stock

Series E Convertible Preferred Stock

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

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Collaborations and license agreements, description of expiry term

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'the Astellas Agreement expires (a)B with respect to the Royalty Territory, on a country by-country basis, upon the latest to occur of: (i)B the expiration of the last-to-expire valid claim of an AVEO patent or joint patent covering the composition of tivozanib, (ii)B the expiration of the last-to-expire valid claim of an AVEO patent or joint patent covering the use of tivozanib, but only for so long as no generic competition exists in such country, and (iii)B twelve years from first commercial sale of tivozanib in such country, and (b)B with respect to North America and Europe as a whole, upon the expiration of all payment obligations between the parties related to development and commercialization of tivozanib in North America and Europe. After the second anniversary of the effective date of the Astellas Agreement, Astellas has the right to terminate the Astellas Agreement, in its entirety or solely with respect to the Royalty Territory, at any time upon 180 days prior written notice to the Company.

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Collaborations and license agreements, written notice period for at will termination

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'180 days

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'6 months

'60 days

Collaborations and license agreements, termination

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'30 days

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Collaborations and license agreements, payment received

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$40,100,000

$39,800,000

$146,400,000

$125,000,000

'

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'

'

'

'

'

'

'

'

'

'

'

$15,000,000

$75,000,000

$50,000,000

'

'

'

'

$1,000,000

$16,500,000

$2,500,000

'

'

'

'

'

'

'

'

$12,500,000

'

$5,000,000

$7,500,000

'

'

$600,000

'

'

'

$2,300,000

$16,300,000

'

'

'

$7,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$5,000,000

'

'

$5,000,000

'

'

'

$700,000

'

'

Collaborations and license agreements, net proceeds

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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97,600,000

'

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'

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'

Payments received and recorded as a reduction to expense pursuant to cost-sharing provisions

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'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15,800,000

34,100,000

26,700,000

2,800,000

3,300,000

1,200,000

'

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'

'

'

'

'

'

'

'

'

'

'

'

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'

'

Amounts due from Astellas pursuant to the cost-sharing provisions

984,000

'

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20,649,000

'

'

'

984,000

20,649,000

'

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'

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'

'

'

'

'

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1,000,000

'

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'

'

Collaborations and license agreements, relative selling price of the deliverable

'

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'

'

'

'

'

'

'

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'

'

'

'

'

'

'

'

'

125,000,000

'

'

'

'

'

'

'

'

120,200,000

4,800,000

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

39,000,000

'

'

'

7,000,000

7,000,000

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaborations and license agreements, revenue recognized

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

400,000

15,400,000

120,600,000

'

'

'

'

'

'

'

'

'

120,200,000

'

400,000

400,000

'

'

'

'

'

'

'

'

1,000,000

29,600,000

'

'

'

'

'

'

'

'

12,500,000

'

25,000,000

'

'

3,900,000

900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

900,000

900,000

5,900,000

'

'

'

8,200,000

'

'

'

'

'

Collaborations and license agreements, deferred revenue

'

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'

'

'

'

'

'

'

'

'

'

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'

'

'

'

'

'

'

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'

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'

'

'

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'

'

4,800,000

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'

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'

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'

'

Collaborations and license agreements, deferred revenue recognition period

'

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'

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'

'

'

'

'

'

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'

'

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'

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'Through April 2022

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'

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'

'

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'

'

Shares of stock sold, number of shares

'

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'

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'

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'

'

'

'

'

'

'

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,750,000

'

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'

'

1,833,334

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

438,340

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,500,000

'

'

'

'

'

'

'

'

Shares of stock sold, price per shares

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$4

'

'

'

'

$3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$17.11

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$4

'

'

'

'

'

'

'

'

Proceeds from issuance of Convertible Preferred Stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15,000,000

'

'

'

'

5,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

30,000,000

'

'

'

'

'

'

'

'

Reverse stock split, ratio

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.25

'

'

'

'

0.25

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.25

'

'

'

'

'

'

'

'

Reverse stock split, number of shares of outstanding stock converted into one share of common stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4

'

'

'

'

4

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4

'

'

'

'

'

'

'

'

Shares of stock sold, discount (premium) over the fair value per share

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1.04

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1.09

'

'

'

'

'

'

'

'

Fair value of stock calculated in retrospective stock valuation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2.96

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2.91

'

'

'

'

'

'

'

'

Collaborations and license agreements, milestone payment received

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

300,000

800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,000,000

5,000,000

5,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaborations and license agreements, expected milestone receivable

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

46,000,000

'

2,000,000

'

'

'

'

'

8,400,000

20,700,000

17,500,000

24,000,000

7,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

45,000,000

'

'

'

'

5,000,000

'

'

25,000,000

'

'

'

'

Shares of stock sold, discount (premium) from closing stock price per share

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0.50

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1.22

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares of stock sold, value of shares

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares of stock sold, closing stock price per share

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$18.33

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares of stock sold, discount from fair market value of stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

534,775

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Revenue

323,000

323,000

324,000

323,000

15,531,000

1,018,000

1,877,000

860,000

1,293,000

19,286,000

164,849,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,000,000

8,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payment to purchase a supply of ficlatuzumab

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaborations and license agreements, cash payment

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaborations and license agreements, milestone payment

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

12,000,000

'

10,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Research and development expense

'

'

'

'

'

'

'

'

68,468,000

91,358,000

101,735,000

25,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

22,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reimbursement cost

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaborations and license agreements, potential future milestone payments, maximum amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

18,000,000

4,500,000

9,000,000

'

'

'

'

'

'

'

'

'

'

'

'

9,200,000

'

'

'

Collaborations and license agreements, potential future payment as percentage of certain amounts the Company receives under the Astellas Agreement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

30.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaborations and license agreements, time period from first commercial sale of certain product upon which the agreement expires

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'10 years

'

'

'

Termination period in case of breach of contract

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'4 months

'

'

'

Invalidation date of licensed patents

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'2014-07

License payment per product

'

'

'

'

'

'

'

'

'

'

'

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Development and sales-based milestones payment

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

22,500,000

5,500,000

4,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collaborations and license agreements, royalties payment on net sales

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.50%

1.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

License expense

'

'

'

'

'

'

'

'

'

'

'

$0

$300,000

$500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)

12 Months Ended

1 Months Ended

0 Months Ended

0 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Jul. 31, 2004

Dec. 31, 2013

Dec. 31, 2012

Feb. 28, 2011

Dec. 31, 2013

Dec. 31, 2012

Nov. 30, 2011

Dec. 31, 2013

Dec. 31, 2012

Nov. 04, 2011

Nov. 30, 2011

9-May-12

Dec. 31, 2013

Dec. 31, 2012

9-May-12

9-May-12

Minimum

Maximum

Millennium Pharmaceuticals, Inc.

Millennium Pharmaceuticals, Inc.

Millennium Pharmaceuticals, Inc.

Acceleron Pharma, Inc.

Acceleron Pharma, Inc.

Acceleron Pharma, Inc.

Massachusetts Institute of Technology

Massachusetts Institute of Technology

Massachusetts Institute of Technology

Massachusetts Institute of Technology

Massachusetts Institute of Technology

BMR-650 E KENDALL B LLC

BMR-650 E KENDALL B LLC

BMR-650 E KENDALL B LLC

BMR-650 E KENDALL B LLC

BMR-650 E KENDALL B LLC

sqft

sqft

sqft

Maximum

sqft

Phase 1 Space

Phase 2 Space

sqft

Commitment And Contingencies [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Rent expense

$9,400,000

$7,800,000

$2,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Sublease agreement, square feet of property subleased

'

'

'

'

'

55,200

'

'

14,214

'

'

'

'

'

'

'

'

'

'

'

'

Lease agreement, expiration date

'

'

'

'

'

28-Feb-14

'

'

30-May-15

'

'

28-Feb-14

'

'

'

31-May-15

'

'

'

'

'

Lease agreement, letter of credit outstanding

'

'

'

'

'

600,000

'

'

100,000

'

'

'

'

'

46,000

'

2,900,000

'

'

'

'

Lease agreement, letter of credit expiration date automatic extensions periods

'

'

'

'

'

'1 year

'

'

'1 year

'

'

'1 year

'

'

'

'

'

'

'

'

'

Lease agreement, letter of credit expiration date

'

'

'

'

'

12-Jul-14

'

'

31-May-14

'

'

29-Apr-13

'

'

'

'

'

'

'

'

'

Free rent period received

'

'

'

'

'

'6 months

'

'

'

'

'

'42 days

'

'

'

'

'

'

'

'

'

Deferred rent

'

'

'

'

'

'

42,000

300,000

'

19,000

32,000

'

13,000

82,000

'

'

'

20,000,000

11,000,000

'

'

Lease agreement, square feet of property leased

'

'

'

'

'

'

'

'

'

'

'

11,500

'

'

'

'

'

'

'

'

'

Tenant improvement allowance

'

'

'

'

'

'

'

'

'

'

'

115,000

'

'

'

'

'

'

'

'

'

Lease agreement, square feet of property leased

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

126,065

'

'

26,734

'

Lease agreement, initial term

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'12 years 7 months

'

'

'

'

Lease agreement, number of additional extension terms

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

Lease agreement, optional extension term

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'5 years

'

'

'

'

Lease agreement, number of occupancy phases of leased space

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

Lease agreement, occupancy of leased space beginning period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4-Jan-13

'

Lease agreement, rent payments start date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1-Jan-13

1-Nov-13

Lease agreement, initial base rent expense per rental square foot per year

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

54.5

'

'

'

'

Lease agreement, percentage of increase in base rent expense on each anniversary of phase one space rent commencement date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.00%

'

'

'

'

Operating lease, rent expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6,700,000

4,900,000

'

'

Operating lease, maximum lease improvements reimbursement amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$20,000,000

'

'

'

'

Severance and bonus payment period

'

'

'

'12 months

'18 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Severance and bonus payment period

'

'

'

'6 months

'18 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Future_Annual_Minimum_Lease_Pa

Future Annual Minimum Lease Payments (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Operating Leased Assets [Line Items]	'
2014	$8,077
2015	7,530
2016	7,508
2017	7,733
2018 and thereafter	61,030
Operating Leases, Future Minimum Payments Due, Total	$91,878

Reconciliation_of_Expected_Inc

Reconciliation of Expected Income Tax Benefit (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule Of Effective Tax Rates Line Items	'	'	'
Income tax computed at federal statutory tax rate	34.00%	34.00%	34.00%
State taxes, net of federal benefit	5.10%	5.10%	5.30%
Research and development credits	2.00%	0.10%	-5.10%
Permanent differences	-0.90%	-1.20%	2.80%
Foreign rate differential	-0.20%	-0.40%	0.00%
Other	-0.50%	-0.20%	0.30%
Change in valuation allowance	-39.50%	-37.40%	-37.30%
Total	0.00%	0.00%	0.00%

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]	'	'	'
Operating loss carryforwards, net	$4,100,000	'	'
Increase in valuation allowance	42,300,000	'	'
Unrecognized tax benefits	1,200,000	1,200,000	1,200,000
Internal Revenue Service (IRS)	'	'	'
Income Taxes [Line Items]	'	'	'
Operating loss carryforwards, net	348,800,000	'	'
Research and development tax credit carryforwards	8,700,000	'	'
Internal Revenue Service (IRS) | Minimum	'	'	'
Income Taxes [Line Items]	'	'	'
Operating loss carryforwards, expiration year	'2022	'	'
Research and development tax credit, expiration year	'2022	'	'
Internal Revenue Service (IRS) | Maximum	'	'	'
Income Taxes [Line Items]	'	'	'
Operating loss carryforwards, expiration year	'2033	'	'
Research and development tax credit, expiration year	'2033	'	'
State and Local Jurisdiction	'	'	'
Income Taxes [Line Items]	'	'	'
Operating loss carryforwards, net	259,900,000	'	'
Research and development tax credit carryforwards	4,000,000	'	'
State and Local Jurisdiction | Minimum	'	'	'
Income Taxes [Line Items]	'	'	'
Operating loss carryforwards, expiration year	'2014	'	'
Research and development tax credit, expiration year	'2019	'	'
State and Local Jurisdiction | Maximum	'	'	'
Income Taxes [Line Items]	'	'	'
Operating loss carryforwards, expiration year	'2033	'	'
United Kingdom	'	'	'
Income Taxes [Line Items]	'	'	'
Operating loss carryforwards, net	$6,900,000	'	'

Company_Net_Deferred_Tax_Asset

Company Net Deferred Tax Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deferred Income Tax Asset [Line Items]	'	'
NOL carryforwards	$134,023	$99,001
Research and development credits	11,357	7,960
Deferred revenue	7,224	7,732
Other temporary differences	15,158	10,776
Valuation allowance	-167,762	-125,469
Deferred Tax Assets, Net of Valuation Allowance, Total	'	'

Reconciliation_of_Gross_Uncert

Reconciliation of Gross Uncertain Tax Positions (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]	'	'
Amount established upon adoption	$1,200	$1,200
Additions for current year tax positions	'	'
Additions for prior year tax positions	'	'
Reductions of prior year tax positions	'	'
Balance as of end of year	$1,200	$1,200

Common_Stock_and_Warrants_Addi

Common Stock and Warrants - Additional Information (Detail) (USD $)	12 Months Ended			0 Months Ended	1 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2011	Dec. 31, 2012	31-May-11	Jan. 31, 2013	Jun. 30, 2011	Jan. 31, 2013	Jun. 30, 2011	Jan. 31, 2013
				Private Placement	Public Offering	Public Offering	Underwriters Option	Underwriters Option	Initial Public Offering
Class of Warrant or Right [Line Items]	'	'	'	'	'	'	'	'	'
Common stock, shares authorized	100,000,000	'	100,000,000	'	'	'	'	'	'
Common stock, par value	$0.00	'	$0.00	'	'	'	'	'	'
Common stock, shares issued	51,809,028	'	43,779,560	'	'	'	'	'	'
Common stock, shares outstanding	51,809,028	'	43,779,560	'	'	'	'	'	'
Number of warrants outstanding	0	'	'	'	'	'	'	'	'
Issuance of common stock, share	'	'	'	438,340	7,667,050	5,750,000	1,000,050	602,119	6,667,000
Issuance of common stock, per share	'	'	'	$17.11	'	$17.50	$7.50	$17.50	'
Proceeds from issuance of common stock, net of issuance costs	$53,637	$112,130	'	$7,500	$53,600	$104,200	'	'	'
Issuance of common stock, value	'	'	'	'	'	100,600	'	10,500	'
Issuance of common stock, issuance costs	'	'	'	'	$3,900	$7,000	'	'	'

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)

12 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2008

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 31, 2013

Feb. 28, 2010

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jun. 28, 2013

Jun. 29, 2012

Dec. 30, 2011

Jan. 03, 2011

Dec. 31, 2013

Dec. 31, 2013

Mar. 31, 2013

Stock Options

Stock Options

Stock Options

Stock Options

Restricted Stock

Restricted Stock

Restricted Stock

Employee Stock Purchase Plan, 2010

Employee Stock Purchase Plan, 2010

Employee Stock Purchase Plan, 2010

Employee Stock Purchase Plan, 2010

Employee Stock Purchase Plan, 2010

Employee Stock Purchase Plan, 2010

Employee Stock Purchase Plan, 2010

Employee Stock Purchase Plan, 2010

Employee Stock Purchase Plan, 2010

Minimum

Minimum

Maximum

Non Employees

Stock Options

Stock Options

Participants Who Own Less than 10% of Total Combined Voting Power

Participants Who Own More than 10% of Total Combined Voting Power

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Employee stock purchase plan, number of shares authorized to sell

'

'

'

7,875,000

'

'

'

'

'

'

'

'

250,000

'

'

'

'

'

'

'

'

'

'

Common stock reserved for issuance

8,477,664

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

625,000

Stock-based award per share purchase price percentage to fair market value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

Number of shares for each one share of common stock subject to full-value award

'

'

'

1.5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares available for future issuance under the Plan

5,362,977

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Exercise price of incentive stock options as percentage of fair market value of common stock on the date of the award

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

110.00%

'

Awards, vesting period

'

'

'

'

'4 years

'

'

'

'4 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Awards, Expiration period

'

'

'

'

'10 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted-average grant date fair value of stock options granted

'

'

'

'

$4.32

$7.40

$9.55

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total unrecognized stock-based compensation expense

'

'

'

'

$3,100,000

'

'

'

$100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total unrecognized stock-based compensation expense, weighted-average period Recognition

'

'

'

'

'1 year 9 months 18 days

'

'

'

'9 months 18 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Intrinsic value of options exercised

'

'

'

'

500,000

1,900,000

6,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares of nonqualified common stock options granted to nonemployee consultants

2,715,840

'

'

'

'

'

'

50,625

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares of nonqualified common stock options granted to nonemployee consultants, average exercise price

$4.95

'

'

'

'

'

'

$6.84

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of restricted stock awards vested

'

'

'

'

'

'

'

'

500,000

500,000

0

'

'

'

'

'

'

'

'

'

'

'

'

Reversal of stock-based compensation expense

'

'

'

'

'

'

'

'

2,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Employee stock purchase plan, number of additional shares available to sell

'

'

'

'

'

'

'

'

'

'

'

764,000

'

'

'

'

'

'

'

'

'

'

'

Common stock price per share percentage as of lower of fair market value of the common stock

'

'

'

'

'

'

'

'

'

'

'

'

85.00%

'

'

'

'

'

'

'

'

'

'

employee stock purchase plan, each offering period

'

'

'

'

'

'

'

'

'

'

'

'6 months

'

'

'

'

'

'

'

'

'

'

'

Employee stock purchase plan, number of share sold

'

'

'

'

'

'

'

'

'

'

'

'

'

109,610

94,592

57,187

'

'

'

'

'

'

'

Price per share of shares sold to employees

'

'

'

'

'

'

'

'

'

'

'

'

'

$1.56

$6.84

'

$2.13

$10.34

$14.62

$12.64

'

'

'

Stock-based compensation expense

$3,940,000

$8,007,000

$5,903,000

'

'

'

'

'

'

'

'

'

'

$200,000

$300,000

$300,000

'

'

'

'

'

'

'

Assumptions_Used_in_Black_Scho

Assumptions Used in Black Scholes Pricing Model for New Grants (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Dividend Yield	'	'	'
Minimum	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Volatility	64.22%	64.30%	64.37%
Expected term (in years)	'5 years 6 months	'5 years 6 months	'5 years 6 months
Risk-free interest rates	1.01%	0.83%	1.09%
Maximum	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Volatility	72.65%	66.05%	65.56%
Expected term (in years)	'6 years 3 months	'6 years 3 months	'6 years 3 months
Risk-free interest rates	2.10%	1.33%	2.57%

Stock_Option_Activity_Detail

Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Options	'
Outstanding at beginning of period	4,638,388
Granted	2,715,840
Exercised	-185,311
Forfeited	-1,860,918
Expired	-1,011,305
Outstanding at end of period	4,296,694
Exercisable at December 31, 2013	2,676,724
Vested or expected to vest at December 31, 2013	3,598,721
Weighted-Average Exercise Price	'
Outstanding at beginning of period	$9.86
Granted	$4.95
Exercised	$1.46
Forfeited	$8.81
Expired	$10.80
Outstanding at end of period	$7.36
Exercisable at December 31, 2013	$8.53
Vested or expected to vest at December 31, 2013	$7.90
Weighted-Average Remaining Contractual Term	'
Outstanding at December 31, 2013	'5 years 9 months 26 days
Exercisable at December 31, 2013	'4 years 1 month 21 days
Vested or expected to vest at December 31, 2013	'5 years 3 months 4 days
Aggregate Intrinsic Value	'
Outstanding at December 31, 2013	$130,676
Exercisable at December 31, 2013	130,676
Vested or expected to vest at December 31, 2013	$130,676

Restricted_Stock_Activity_Deta

Restricted Stock Activity (Detail) (Restricted Stock, USD $)	12 Months Ended
	Dec. 31, 2013
Restricted Stock	'
Number of Shares	'
Unvested at beginning of period	245,020
Granted	689,678
Cancelled	-660,698
Expired	'
Vested/Released	-32,500
Unvested at end of period	241,500
Weighted-Average Grant-Date Fair Value	'
Unvested at beginning of period	$13.31
Granted	$5.23
Cancelled	$8.79
Expired	'
Vested/Released	$14.16
Unvested at end of period	$2.50

Employee_Benefit_Plan_Addition

Employee Benefit Plan - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]	'	'	'
401(k) Plan, matching employer contribution percentage	50.00%	'	'
401(k) Plan, employee contributions percentage	5.00%	'	'
Contributions made under the plan	$0.40	$0.60	$0.40

Strategic_Restructuring_Additi

Strategic Restructuring - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	Oct. 31, 2012	Dec. 31, 2013
	Position
Restructuring Cost and Reserve [Line Items]	'	'
Restructuring plan, expected number of positions eliminated	48	'
Restructuring expense incurred	'	$7,756,000
Restructuring expense including impairment charges	'	$300,000
Open Position	'	'
Restructuring Cost and Reserve [Line Items]	'	'
Restructuring plan, expected number of positions eliminated	30	'

Restructuring_Activity_Recorde

Restructuring Activity Recorded in Operating Expenses and Accrued Expenses (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]	'	'
Restructuring amounts accrued, beginning balance	$1,653	'
Restructuring expense incurred	7,756	'
Restructuring amounts paid	-8,822	'
Restructuring amounts accrued, ending balance	587	'
Employee Severance	'	'
Restructuring Cost and Reserve [Line Items]	'	'
Restructuring amounts accrued, beginning balance	1,653	'
Restructuring expense incurred	7,674	2,633
Restructuring amounts paid	-8,740	-980
Restructuring amounts accrued, ending balance	587	1,653
Contract Termination	'	'
Restructuring Cost and Reserve [Line Items]	'	'
Restructuring expense incurred	82	'
Restructuring amounts paid	($82)	'

Summary_of_Quarterly_Results_D

Summary of Quarterly Results (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Collaboration revenue	$323	$323	$324	$323	$15,531	$1,018	$1,877	$860	$1,293	$19,286	$164,849
Restructuring	4	77	7,869	67	2,633	'	'	'	8,017	2,633	'
Operating expenses	16,392	23,931	31,396	33,478	36,129	30,399	30,636	33,759	105,197	130,923	130,902
Loss from operations	-16,069	-23,608	-31,072	-33,155	-20,598	-29,381	-28,759	-32,899	-103,904	-111,637	33,947
Other expense, net	-656	-698	-841	-930	-882	-741	-787	-347	-3,125	-2,757	-3,299
Net loss	($16,725)	($24,306)	($31,913)	($34,085)	($21,480)	($30,122)	($29,546)	($33,246)	($107,029)	($114,394)	$30,648
Net loss per share-basic and diluted	($0.32)	($0.47)	($0.62)	($0.69)	($0.49)	($0.69)	($0.68)	($0.77)	'	'	'

Legal_Actions_Additional_Infor

Legal Actions -Additional Information (Detail)	12 Months Ended
	Dec. 31, 2013
	LegalMatter
Legal Proceedings [Line Items]	'
Class action lawsuits	2

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (Subsequent Event, Astellas Pharma Inc., Collaborative Arrangements, Co-promotion Agreement, Agreement)	Feb. 28, 2014
Subsequent Event | Astellas Pharma Inc. | Collaborative Arrangements, Co-promotion Agreement, Agreement	'
Subsequent Event [Line Items]	'
Effective termination month and year	'2014-08