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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2016	Feb. 24, 2017	Jun. 30, 2016
Document And Entity Information
Entity Registrant Name	Ophthotech Corp.
Entity Central Index Key	0001410939
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,616.0
Entity Common Stock, Shares Outstanding		35,808,442
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY

Balance Sheets - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 133,930,000	$ 221,861,000
Available for sale securities	155,348,000	74,731,000
Due from Novartis Pharma AG	3,531,000	4,389,000
Prepaid expenses and other current assets	3,078,000	5,504,000
Total current assets	295,887,000	306,485,000
Available for sale securities	0	95,298,000
Property and equipment, net	3,281,000	3,466,000
Deferred tax assets	0	23,113,000
Other assets	462,000	489,000
Total assets	299,630,000	428,851,000
Current liabilities
Accrued research and development expenses	47,240,000	18,820,000
Accounts payable and accrued expenses	12,032,000	12,018,000
Deferred revenue	6,646,000	6,667,000
Total current liabilities	65,918,000	37,505,000
Deferred revenue, long-term	203,330,000	206,399,000
Royalty purchase liability	125,000,000	125,000,000
Total liabilities	394,248,000	368,904,000
Stockholders' equity (deficit)
Preferred stock—$0.001 par value, 5,000,000 shares authorized, no shares issued or outstanding	0	0
Common stock—$0.001 par value, 200,000,000 shares authorized, 35,733,276 and 35,196,567 shares issued and outstanding at December 31, 2016 and December 31, 2015, respectively	36,000	35,000
Additional paid-in capital	504,517,000	465,924,000
Accumulated deficit	(598,959,000)	(405,539,000)
Accumulated other comprehensive loss	(212,000)	(473,000)
Total stockholders' equity (deficit)	(94,618,000)	59,947,000
Total liabilities and stockholders' equity (deficit)	$ 299,630,000	$ 428,851,000

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	35,733,276	35,196,567
Common stock, shares outstanding (in shares)	35,733,276	35,196,567

Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Collaboration revenue	$ 50,909	$ 51,505	$ 41,259
Operating expenses:
Research and development	196,295	131,012	88,385
General and administrative	50,178	44,021	33,387
Total operating expenses	246,473	175,033	121,772
Loss from operations	(195,564)	(123,528)	(80,513)
Interest income	1,704	971	217
Other income	34	53	0
Loss before income tax (benefit) provision	(193,826)	(122,504)	(80,296)
Income tax (benefit) provision	(406)	(16,787)	36,476
Net loss	$ (193,420)	$ (105,717)	$ (116,772)
Net loss per common share:
Basic and diluted (in dollars per share)	$ (5.45)	$ (3.06)	$ (3.51)
Weighted average common shares outstanding:
Basic and diluted (in shares)	35,486	34,580	33,258

Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
Statements of Comprehensive Loss - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (193,420)	$ (105,717)	$ (116,772)
Other comprehensive income (loss):
Unrealized gain (loss) on available for sale securities, net of tax	261	(408)	(65)
Other comprehensive income (loss)	261	(408)	(65)
Comprehensive loss	$ (193,159)	$ (106,125)	$ (116,837)

Statements of Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Total	Junior Series A Preferred Stock	Common Stock	Additional paid-in capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period at Dec. 31, 2013	$ 169,720	$ 0	$ 31	$ 352,739	$ (183,050)	$ 0
Balance at beginning of period (in shares) at Dec. 31, 2013		0	31,413
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants	2,949		$ 1	2,948
Issuance of common stock under employee stock compensation plans and warrants (in shares)			682
Issuance from follow-on public offering, net	55,409		$ 2	55,407
Issuance from follow-on public offering, net (in shares)			1,900
Share-based compensation	13,040			13,040
Excess tax benefit from share-based compensation	4,256			4,256
Net loss	(116,772)				(116,772)
Unrealized gain (loss) on available for sale securities, net of tax	(65)					(65)
Ending balance at Dec. 31, 2014	128,537	$ 0	$ 34	428,390	(299,822)	(65)
Balance at end of period (in shares) at Dec. 31, 2014		0	33,995
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants	11,473		$ 1	11,472
Issuance of common stock under employee stock compensation plans and warrants (in shares)			1,202
Share-based compensation	24,760			24,760
Excess tax benefit from share-based compensation	1,302			1,302
Net loss	(105,717)				(105,717)
Unrealized gain (loss) on available for sale securities, net of tax	(408)					(408)
Ending balance at Dec. 31, 2015	59,947	$ 0	$ 35	465,924	(405,539)	(473)
Balance at end of period (in shares) at Dec. 31, 2015		0	35,197
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants	6,934		$ 1	6,933
Issuance of common stock under employee stock compensation plans and warrants (in shares)			536
Share-based compensation	31,660			31,660
Excess tax benefit from share-based compensation	0
Net loss	(193,420)				(193,420)
Unrealized gain (loss) on available for sale securities, net of tax	261					261
Ending balance at Dec. 31, 2016	$ (94,618)	$ 0	$ 36	$ 504,517	$ (598,959)	$ (212)
Balance at end of period (in shares) at Dec. 31, 2016		0	35,733

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net loss	$ (193,420)	$ (105,717)	$ (116,772)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Depreciation	757	698	127
Amortization of premium and discounts on investment securities	595	2,846	2,024
Gain on sale of marketable securities	0	(57)	0
Deferred income taxes	22,954	(17,341)	(214)
Share-based compensation	31,660	24,760	13,040
Excess tax benefits from share-based compensation	0	(1,302)	(4,256)
Changes in operating assets and liabilities:
Due from Novartis Pharma AG	858	(3,429)	(960)
Prepaid expense and other current assets	2,426	3,308	(2,008)
Accrued interest receivable	203	155	280
Other assets	27	(107)	(127)
Accrued research and development expenses	28,420	10,902	5,433
Accounts payable and accrued expenses	14	3,311	4,897
Deferred revenue	(3,090)	3,442	209,624
Net cash (used in) provided by operating activities	(108,596)	(78,531)	111,088
Investing Activities
Purchase of marketable securities	(72,197)	(411,565)	(597,762)
Sale of marketable securities	0	395,977	0
Maturities of marketable securities	86,500	266,000	171,600
Purchase of property and equipment	(572)	(2,615)	(1,655)
Proceeds from sale of assets	0	6	0
Net cash provided by (used in) investing activities	13,731	247,803	(427,817)
Financing Activities
Proceeds from stock option/warrant exercises	6,934	11,473	2,949
Proceeds from follow-on public offering, net	0	0	55,409
Excess tax benefits from share-based compensation	0	1,302	4,256
Proceeds from royalty purchase agreement	0	0	83,333
Net cash provided by financing activities	6,934	12,775	145,947
Net change in cash and cash equivalents	(87,931)	182,047	(170,782)
Cash and cash equivalents
Beginning of period	221,861	39,814	210,596
End of period	133,930	221,861	39,814
Supplemental disclosure of cash paid
Income taxes paid (received), net	(26,998)	399	40,159
Supplemental disclosures of non-cash information related to investing activities
Change in unrealized gain (loss) on available for sale securities, net of tax	$ 261	$ (408)	$ (65)

Business	12 Months Ended
Business	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	1. Business Description of Business and Organization Ophthotech Corporation (the “Company” or “Ophthotech”) was incorporated on January 5, 2007, in Delaware. The Company is a biopharmaceutical company specializing in the development of novel therapeutics to treat ophthalmic diseases, with a focus on diseases of the back of the eye. To date, the Company's primary focus has been on developing therapeutics for age-related macular degeneration, or AMD, which is a disorder of the central portion of the retina, known as the macula, that may result in blindness. Following the Company's announcement in December 2016 that two of its three pivotal, Phase 3 clinical trials for Fovista® (pegpleranib), an anti-platelet derived growth factor, or PDGF, aptamer, in development for the treatment of wet AMD, failed to meet their primary endpoint, the Company initiated a plan to review its strategic alternatives in order to maximize shareholder value and implement an updated business plan. Without limiting any option, the Company plans to continue to focus on the development of product candidates for ophthalmic diseases, especially back of the eye disorders. The Company is actively exploring opportunities to obtain rights to additional products, product candidates and technologies to treat ophthalmic diseases. The Company is also currently continuing to develop its product candidate Zimura® (avacincaptad pegol), an inhibitor of complement factor C5, for the treatment of geographic atrophy, or GA, a form of dry AMD, and in combination with anti-VEGF drugs for the treatment of wet AMD, and is continuing its remaining Phase 3 Fovista clinical trial, OPH1004. The Company plans to reassess its existing Fovista and Zimura development programs throughout 2017 as the implementation of its updated business plan progresses and evolves, with the goal of aligning corporate resources in the context of a potentially broader product pipeline. The Company expects that its reassessment of its Fovista development program for the treatment of wet AMD will be primarily determined by the initial, top-line data from OPH1004 and that its reassessment of its Zimura development program may be particularly affected by the results of a competitor’s Phase 3 clinical trial of a complement inhibitor being studied for the treatment of GA. Data from both the Company's OPH1004 trial and its competitor’s Phase 3 trial for the treatment of GA are expected during the second half of 2017. As a result of this reassessment, the Company may modify, expand or terminate some or all of its development programs or clinical trials at any time. The Company generally expects that it will not engage in internal early stage research and drug discovery and will thus avoid the related costs and risks of these activities.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States ("GAAP") and include all adjustments necessary for the fair presentation of the Company's financial position for the periods presented.

Segment and geographic information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating and reporting segment.

Use of Estimates

The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company's Balance Sheets and the amount of expenses reported for each of the periods presented are affected by estimates and assumptions, which are used for, but not limited to, accounting for research and development costs, revenue recognition, accounting for share-based compensation and accounting for income taxes. Actual results could differ from those estimates.

Cash and Cash Equivalents

The Company considers all highly liquid investments with an original maturity of 90 days or less when purchased to be cash equivalents. The carrying amounts reported in the Balance Sheets for cash and cash equivalents are valued at cost, which approximates their fair value.

As of December 31, 2016, the Company had cash, cash equivalents and available for sale securities of approximately $289.3 million. The Company believes that its existing cash, cash equivalents and available-for-sale securities as of December 31, 2016 will be sufficient to fund its operations and capital expenditure requirements as currently planned for at least the next 12 months.

Available for Sale Securities

The Company considers securities with original maturities of greater than 90 days when purchased to be available for sale securities. Available for sale securities with original maturities of greater than one year are recorded as non-current assets. Available for sale securities are recorded at fair value and unrealized gains and losses are recorded within accumulated other comprehensive income (loss). The estimated fair value of the available for sale securities is determined based on quoted market prices or rates for similar instruments. In addition, the cost of debt securities in this category is adjusted for amortization of premium and accretion of discount to maturity. The Company evaluates securities with unrealized losses to determine whether such losses, if any, are other than temporary.

Revenue Recognition

Collaboration Revenue

Prior to 2014, the Company had not generated any revenue. In May 2014, the Company received an upfront payment of $200.0 million in connection with its licensing and commercialization agreement with Novartis Pharma AG, (the "Novartis Agreement"), which has not been recorded as revenue due to certain contingencies associated with the payment. In each of September 2014 and March 2015, the Company achieved a $50.0 million enrollment-based milestone, and in June 2016, the Company achieved a $30.0 million enrollment-based milestone, for an aggregate total of $130.0 million, under the Novartis Agreement. The Company uses the relative selling price method to allocate arrangement consideration to the Company's performance obligations under the Novartis Agreement. Below is a summary of the components of the Company's collaboration revenue for the years ended December 2016, 2015 and 2014:



	Years ended December 31,
	2016		2015		2014
License revenue	$	22,937	$	38,083	$	38,373
Research and development activity revenue	9,741		8,378		2,000
API transfer revenue	18,212		5,020		883
Joint operating committee revenue	19		24		3
Total collaboration revenue	$	50,909	$	51,505	$	41,259

In the future, the Company may generate additional revenues from a combination of product sales and license fees, milestone payments, research and development activity-related payments, payments for manufactured material and royalties in connection with the Novartis Agreement. The terms of this agreement and other potential collaboration or commercialization agreements the Company may enter into generally contain multiple elements, or deliverables, which may include (i) licenses, or options to obtain licenses, to certain of the Company's technology and products, (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 preclinical, clinical and commercial material. Payments to the Company under these arrangements typically include one or more of the following: non-refundable, upfront license fees; option exercise fees; funding of research and/or development efforts; milestone payments; payments for manufactured material; 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 ("BESP") if neither VSOE nor TPE is available. Determining the best estimate of selling price for a deliverable requires significant judgment. The Company uses BESP 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 BESP 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 as well as 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 that is subject to the license. In validating the Company's BESP, the Company evaluates whether changes in the key assumptions used to determine the BESP will have a significant effect on the allocation of arrangement consideration among multiple deliverables.

When management believes the license to its intellectual property and products has stand-alone value, the Company generally recognizes revenue attributed to the license upon delivery. When management believes such a license 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. 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.

At the inception of arrangements that include 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 three categories: (i) clinical and development milestones, (ii) regulatory milestones, and (iii) commercial milestones. Clinical and development milestones are typically achieved when a product candidate advances into a defined phase of clinical research or completes such phase or when a contractually specified clinical trial enrollment target is attained. Regulatory milestones are typically achieved upon acceptance of the submission of an application for marketing approval for a product candidate or upon approval to market the product candidate by the U.S. Food and Drug Administration (the "FDA") or other regulatory authorities. 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.

Revenues from clinical and development and regulatory milestone payments, if the milestones are deemed substantive and the milestone payments are nonrefundable, are recognized upon successful accomplishment of the milestones. With regard to the Novartis Agreement, the Company has concluded that the clinical and development milestones and certain reimbursement milestones are not substantive and that the marketing approval milestones are substantive. Milestone payments received that are not considered substantive are included in the allocable arrangement consideration and are recognized as revenue in proportion to the relative-selling price allocation established at the inception of the arrangement. 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.

Concentration of Credit Risk

The Company's financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents and available for sale securities. The Company maintains its cash in bank accounts, which generally exceed federally insured limits. The Company maintains its cash equivalents in investments in money market funds and, at times, in U.S. Treasury securities and investment-grade corporate debt securities with original maturities of 90 days or less.

The Company's available for sale securities are also invested in U.S. Treasury securities and investment-grade corporate debt securities. The Company believes it is not exposed to significant credit risk on its cash, cash equivalents and available for sale securities.

Concentration of Suppliers

The Company currently relies exclusively upon a single third-party manufacturer to provide supplies of the active pharmaceutical ingredient, or API, for both Fovista and Zimura. The Company also engages a single third-party manufacturer to provide fill/finish services for clinical supplies of both Fovista and Zimura. In addition, the Company currently relies exclusively upon Nektar Therapeutics, or Nektar, to supply it with a proprietary polyethylene glycol, or PEG, reagent for Fovista under a manufacturing and supply agreement. PEG reagent is a chemical the Company uses to modify the chemically synthesized aptamer in Fovista. The PEG reagent made by Nektar is proprietary to Nektar. The Company obtains a different proprietary PEG reagent used to modify the chemically synthesized aptamer in Zimura from a different supplier on a purchase order basis. Furthermore, the Company and its contract manufacturers currently rely upon sole-source suppliers of certain raw materials and other specialized components of production used in the manufacture and fill/finish of each of Fovista and Zimura. If the Company’s third-party manufacturers or fill/finish service providers should become unavailable to the Company for any reason, including as a result of capacity constraints, financial difficulties or insolvency, the Company believes that there are a limited number of potential replacement manufacturers, and the Company likely would incur added costs and delays in identifying or qualifying such replacements.

Foreign Currency Translation

The Company considers the U.S. dollar to be its functional currency. Expenses denominated in foreign currencies are translated at the exchange rate on the date the expense is incurred. The effect of exchange rate fluctuations on translating foreign currency assets and liabilities into U.S. dollars is included in the Statements of Operations. Foreign exchange transaction gains and losses are included in the results of operations and are not material in the Company's financial statements.

Financial Instruments

Cash equivalents and available for sale securities are reflected in the accompanying financial statements at fair value. The carrying amount of accounts payable and accrued expenses, including accrued research and development expenses, approximates fair value due to the short-term nature of those instruments.

Property and Equipment

Property and equipment, which consists mainly of manufacturing and clinical equipment, furniture and fixtures, computers, software, and other office equipment, and leasehold improvements, are carried at cost less accumulated depreciation. Depreciation is computed over the estimated useful lives of the respective assets, generally three to ten years, using the straight-line method.

Research and Development

Research and development expenses primarily consist of costs associated with the manufacturing, development and clinical testing of Fovista and Zimura as well as costs associated with the preclinical development of other product candidates and formulations. Research and development expenses consist of:


•	external research and development expenses incurred under arrangements with third parties, such as contract research organizations ("CROs") and other vendors and contract manufacturing organizations ("CMOs") for the production of drug substance and drug product; and


•	employee-related expenses, including salaries, benefits and share-based compensation expense.

Research and development expenses also include costs of acquired product licenses and related technology rights where there is no alternative future use, costs of prototypes used in research and development, consultant fees and amounts paid to collaborative partners.

All research and development expenses are charged to operations as incurred in accordance with Financial Accounting Standards Board Accounting Standards Codification Topic, or ASC, 730, Research and Development. The Company accounts for non-refundable advance payments for goods and services that will be used in future research and development activities as expenses when the service has been performed or when the goods have been received, rather than when the payment is made.

Income Taxes

The Company utilizes the liability method of accounting for deferred income taxes, as set forth in ASC 740, Income Taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the carrying amounts and the tax basis of assets and liabilities. The Company incurred U.S. federal net operating losses (“NOLs”) in each year from its inception in 2007 through 2013 and utilized these NOLs in 2014. Additionally, the Company incurred a U.S. federal net operating loss in 2015 that has been carried back to 2014. Accordingly, all tax years since 2007 are subject to potential tax examination. In the second quarter of 2016, the Internal Revenue Service began an examination of the Company’s 2014 corporate income tax return. To date, no findings or assessments have been received by the Company.

The Company also received notification from the New York State Department of Taxation and Finance of its intention to perform an audit of the Company's New York State income tax returns for the tax years 2013 and 2014. This audit is scheduled to commence during the second quarter of 2017.

Share-Based Compensation

The Company follows the provisions of ASC 718, Compensation—Stock Compensation, which requires the measurement and recognition of compensation expense for all share-based payment awards made to employees and non-employee directors, including employee stock options, restricted stock units (“RSUs”) and the option granted to employees to purchase shares under the 2016 Employee Stock Purchase Plan (the “ESPP”). Share-based compensation expense is based on the grant date fair value estimated in accordance with the provisions of ASC 718 and is generally recognized as an expense over the requisite service period, net of estimated forfeitures. For grants containing performance-based vesting provisions, expense is recognized over the estimated achievement period.

Stock Options

The Company estimates the fair value of stock options granted to employees and non-employee directors on the date of grant using the Black-Scholes option-pricing model. Due to the lack of trading history, the Company's computation of stock-price volatility is based on the volatility rates of comparable publicly held companies over a period equal to the expected term of the options granted by the Company. The Company's computation of expected term is determined using the "simplified" method, which is the midpoint between the vesting date and the end of the contractual term. The Company believes that it does not have sufficient reliable exercise data in order to justify the use of a method other than the "simplified" method of estimating the expected exercise term of employee stock option grants. The Company utilizes a dividend yield of zero based on the fact that the Company has never paid cash dividends to stockholders and has no current intentions to pay cash dividends. The risk-free interest rate is based on the zero-coupon U.S. Treasury yield at the date of grant for a term equivalent to the expected term of the option.

For stock options granted as consideration for services rendered by consultants, the Company recognizes expense in accordance with the requirements of ASC 505-50, Equity Based Payments to Non-Employees. Consultant stock option grants are recorded as an expense over the vesting period of the underlying stock options. At the end of each financial reporting period prior to vesting, the value of these options, as calculated using the Black-Scholes option-pricing model, will be re-measured using the fair value of the Company's common stock and the non-cash expense recognized during the period will be adjusted accordingly. Since the fair value of options granted to consultants is subject to change in the future, the amount of the future expense will include fair value re-measurements until the stock options are fully vested.

The weighted-average assumptions used to estimate grant date fair value of stock options using the Black-Scholes option pricing model were as follows for the years ended December 31, 2016, 2015 and 2014:



	Years ended December 31,
	2016	2015	2014
Expected common stock price volatility	71%	72%	82%
Risk-free interest rate	1.14% - 2.37%	1.35% - 2.24%	1.61% - 2.13%
Expected term of options (years)	6.1	6.2	6.2
Expected dividend yield	—	—	—

RSUs

The Company estimates the fair value of RSUs granted to employees using the closing market price of the Company's common stock on the date of grant.

ESPP

In April 2016, the board of directors adopted the ESPP pursuant to which the Company may sell up to an aggregate of 1,000,000 shares of common stock. The ESPP was approved by the Company’s stockholders in June 2016. The ESPP is considered compensatory and the fair value of the discount and look back provision are estimated using the Black-Scholes option-pricing model and recognized over the six month withholding period prior to purchase.

Share-based compensation expense includes expenses related to stock options and RSUs granted to employees, non-employee directors and consultants, as well as the option granted to employees to purchase shares under the ESPP, all of which have been reported in the Company’s Statements of Operations as follows:



	Years ended December 31,
	2016		2015		2014
Research and development	$	21,380	$	16,608	$	7,594
General and administrative	10,280		8,152		5,446
Total	$	31,660	$	24,760	$	13,040

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2014-9, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-9"). ASU 2014-9 outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. This new revenue recognition model provides a five-step analysis in determining when and how revenue is recognized. The new model will require revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration a company expects to receive in exchange for those goods or services. The FASB subsequently issued additional clarifying standards to address issues arising from implementation of the new revenue standard, including a one-year deferral of the effective date for the new revenue standard. Public companies should now apply the guidance in ASU 2014-9 to annual reporting periods beginning after December 15, 2017 and interim periods within those annual periods. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim periods within that annual period. Companies may use either a full retrospective or a modified retrospective approach to adopt ASU 2014-9. The Company has not yet completed its final review of the impact of this guidance, however the Company anticipates applying the modified retrospective method upon adoption of ASU 2014-9, effective January 1, 2018.

In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern, which defines management's responsibility to assess an entity's ability to continue as a going concern, and to provide related footnote disclosures if there is substantial doubt about its ability to continue as a going concern. The pronouncement is effective for annual and interim reporting periods ending after December 15, 2016 with early adoption permitted. The Company has adopted ASU 2014-15 effective December 31, 2016. The adoption of this guidance did not have a material impact on the Company's financial statements.

In November 2015, the FASB issued ASU 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes, which updated and simplified the presentation of deferred income taxes. Current GAAP requires an entity to separate deferred income tax assets and liabilities into current and non-current amounts in a classified statement of financial position. The requirement results in little or no benefit to users of financial statements because the classification does not generally align with the time period in which the recognized deferred tax amounts are expected to be recovered or settled. To simplify the presentation of deferred income taxes, the amendments in this update require that deferred tax assets and liabilities be classified as noncurrent in a classified statement of financial position. The current requirement that deferred tax assets and liabilities of a tax-paying component of an entity be offset and presented as a single amount is not affected by the amendments in this update. The amendments in this update are effective for financial statements issued for annual periods beginning after December 15, 2016 and interim periods within those annual periods. Earlier application is permitted as of the beginning of an interim or annual reporting period. The Company has adopted this standard retrospectively, effective December 31, 2015.

In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842). Under the new guidance, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: (1) A lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) A right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. Certain targeted improvements were made to align, where necessary, lessor accounting with the lessee accounting model and Topic 606, Revenue from Contracts with Customers. The new lease guidance simplified the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. Public business entities should apply the amendments in ASU 2016-2 for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years (i.e., January 1, 2019, for a calendar year entity). Early application is permitted for all public business entities and all nonpublic business entities upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company is currently assessing the impact that adopting this new accounting guidance will have on its financial statements and footnote disclosures.

In March 2016, the FASB issued ASU 2016-9, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The amendments are intended to improve the accounting for employee share-based payments and affect all organizations that issue share-based payment awards to their employees. Several aspects of the accounting for share-based payment award transactions are simplified, including: (a) income tax consequences; (b) classification of awards as either equity or liabilities; and (c) classification on the statement of cash flows. For public companies, the amendments are effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted in any interim or annual period. The Company early adopted ASU 2016-09 during the fourth quarter of 2016. Due to the Company's history of operating losses, the adoption did not result in changes to the Company's Net loss or Retained earnings and the classification of excess tax benefits on the statement of cash flows for prior periods have not been adjusted. In connection with the adoption of ASU 2016-9, the Company made a policy election to continue its methodology for the development and application of its forfeiture rate. On a prospective basis, effective the year ended December 31, 2016 the Company will record all excess tax benefits and deficiencies as income tax expense or benefit.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, which clarifies the presentation of certain specific cash flow issues in the Statement of cash flows. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual periods and early adoption is permitted. This new guidance is not expected to have a material impact on the Company’s Consolidated Financial Statements.

Net Loss Per Common Share

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Net Loss Per Common Share

3. Net Loss Per Common Share

Basic and diluted net income (loss) per common share is determined by dividing net income (loss) by the weighted average common shares outstanding during the period. For the periods where there is a net loss, stock options and RSUs have been excluded from the calculation of diluted net loss per common share because their effect would be anti-dilutive. Therefore, the weighted average common shares used to calculate both basic and diluted net loss per common share would be the same. The following table sets forth the computation of basic and diluted net income (loss) per common share for the periods indicated:



	Years ended December 31,
	2016			2015			2014
Basic and diluted net loss per common share calculation:
Net loss	$	(193,420	)	$	(105,717	)	$	(116,772	)
Weighted average common shares outstanding	35,486			34,580			33,258
Net loss per common share—basic and diluted	$	(5.45	)	$	(3.06	)	$	(3.51	)

The following potentially dilutive securities have been excluded from the computations of diluted weighted average common shares outstanding for the periods presented, as they would be anti-dilutive:



	Years ended December 31,
	2016	2015	2014
Stock options outstanding	3,359	3,009	3,680
Restricted stock units	721	288	37
Warrants	—	—	14
Total	4,080	3,297	3,731

Cash, Cash Equivalents and Available for Sale Securities

12 Months Ended

Dec. 31, 2016

Cash, Cash Equivalents, and Short-term Investments [Abstract]

Cash, Cash Equivalents and Available for Sale Securities

4. Cash, Cash Equivalents and Available for Sale Securities

The Company considers all highly liquid investments purchased with original maturities of 90 days or less at the date of purchase to be cash equivalents. Cash and cash equivalents included cash of $25.8 million and $5.5 million at December 31, 2016 and 2015, respectively. Cash and cash equivalents at December 31, 2016 and December 31, 2015 also included $108.1 million and $216.4 million, respectively, of investments in money market funds, U.S. Treasury securities and certain short-term investment-grade corporate debt securities with original maturities of 90 days or less.

The Company considers securities with original maturities of greater than 90 days at the date of purchase to be available for sale securities. The Company held available for sale securities with a fair value totaling $155.3 million and $170.0 million as of December 31, 2016 and 2015, respectively. These available for sale securities consisted of U.S. Treasury securities and investment-grade corporate debt securities. At December 31, 2016, the Company held available for sale securities of $155.3 million with maturities of less than one year. The Company did not hold any securities with maturities of greater than one year at December 31, 2016. The Company evaluates securities with unrealized losses, if any, to determine whether such losses are other than temporary. The Company has determined that there were no other than temporary losses in fair value of its investments as of December 31, 2016. The Company classifies these securities as available for sale, however, the Company does not currently intend to sell its investments and the Company believes it is more likely than not that the Company will recover the carrying value of these investments.

Available for sale securities, including carrying value and estimated fair values, are summarized as follows:



	As of December 31, 2016
	Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury securities	$	120,288	$	6	$	(33	)	$	120,261
Corporate debt securities	35,114		—		(27		)	35,087
Total	$	155,402	$	6	$	(60	)	$	155,348



	As of December 31, 2015
	Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury securities	$	130,507	$	—	$	(311	)	$	130,196
Corporate debt securities	39,995		—		(162		)	39,833
Total	$	170,502	$	—	$	(473	)	$	170,029

The Company's available for sale securities are reported at fair value on the Company's Balance Sheets. Unrealized gains (losses) are reported within accumulated other comprehensive income (loss) in the statements of comprehensive income (loss). The cost of securities sold and any realized gains/losses from the sale of available for sale securities are based on the specific identification method. The changes in accumulated other comprehensive income (loss) associated with the unrealized gain (loss) on available for sale securities for the years ended December 31, 2016 and December 31, 2015 were as follows:



	Years ended December 31,
	2016			2015
Beginning balance	$	(473	)	$	(65	)
Current period changes in fair value before reclassifications, net of tax	261			(351		)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	—			(57		)
Total other comprehensive income (loss)	261			(408		)
Ending balance	$	(212	)	$	(473	)

Licensing and Commercialization Agreement with Novartis Pharma AG

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Licensing and Commercialization Agreement with Novartis Pharma AG

5. Licensing and Commercialization Agreement with Novartis Pharma AG

In May 2014, the Company entered into a licensing and commercialization agreement with Novartis Pharma AG ("Novartis", and such agreement, the "Novartis Agreement"). Under the Novartis Agreement, the Company granted Novartis exclusive rights under specified patent rights, know-how and trademarks controlled by the Company to manufacture, from bulk active pharmaceutical ingredient, or API, supplied by the Company, standalone Fovista products and products combining Fovista with an anti-VEGF drug to which Novartis has rights in a co-formulated product, for the treatment, prevention, cure or control of any human disease, disorder or condition of the eye, and to develop and commercialize those licensed products in all countries outside of the United States (the "Novartis Territory"). The Company has agreed to use commercially reasonable efforts to complete its ongoing pivotal Phase 3 clinical program for Fovista and Novartis has agreed to use commercially reasonable efforts to develop a standalone Fovista product and a co-formulated product containing Fovista and an anti-VEGF drug to which Novartis has rights, as well as a pre-filled syringe presentation of such products and to use commercially reasonable efforts, subject to obtaining marketing approval, to commercialize licensed products in the Novartis Territory in accordance with agreed development and marketing plans. Novartis has also granted the Company options, subject to specified limitations, and to the extent such rights are controlled by Novartis, to obtain exclusive rights from Novartis to develop and commercialize in the United States the co-formulated and pre-filled syringe products developed by Novartis. The Company and Novartis have each granted the other options, subject to specified limitations, to obtain access to study data from certain clinical trials of licensed products that the Company or Novartis may conduct, including for use by the other in regulatory filings in its territory. The Company has agreed to exclusively supply Novartis, and Novartis has agreed to exclusively purchase from the Company, its clinical and commercial requirements for the bulk API for Fovista for use in licensed products in the Novartis Territory. The Company has agreed not to commercialize any product comprising Fovista or any other anti-PDGF product in the ophthalmic field in the Novartis Territory.

Novartis paid the Company a $200.0 million upfront fee upon execution of the Novartis Agreement. Novartis also paid the Company $50.0 million upon the achievement of each of two patient enrollment-based milestones, and $30.0 million upon the achievement of a third, and final, enrollment-based milestone, for an aggregate of $130.0 million. Under the terms of the Novartis Agreement, Novartis is also obligated to pay up to an aggregate of an additional $300.0 million upon achievement of specified regulatory milestones, including marketing approval and reimbursement approval in certain countries in the Novartis Territory. In addition, Novartis has agreed to pay the Company up to an aggregate of an additional $400.0 million if Novartis achieves specified sales milestones in the Novartis Territory. Novartis is also obligated to pay the Company royalties with respect to standalone Fovista products and combination Fovista products that Novartis successfully commercializes. The Company will receive royalties at a mid-thirties percentage of net sales of standalone Fovista products and a royalty of approximately equal value for sales of combination Fovista products. Such royalties are subject to customary deductions, credits, and reductions for lack of patent coverage or market exclusivity. Novartis's obligation to pay such royalties will continue on a licensed product-by-licensed product and country-by-country basis until Novartis's last actual commercial sale of such licensed product in such country. The Company will continue to be responsible for royalties it owes to third parties on sales of Fovista products.

Novartis has agreed to pay the Company’s manufacturing costs for clinical supplies and the Company’s manufacturing costs plus a specified percentage margin for commercial supplies of the bulk API for Fovista that the Company supplies to Novartis. If the Company or Novartis exercises each of their respective rights to obtain access to study data from clinical trials conducted by the other party, the party exercising the option will be obligated to pay the other party's associated past development costs and share with such other party any future associated development costs. If the Company exercises its option to obtain Novartis-controlled rights to develop, manufacture and commercialize any co-formulated Fovista product in the United States, the Company will be obligated to pay a specified percentage of Novartis's associated past development costs and share with Novartis any future associated development costs. The Company and Novartis will also need to negotiate and agree on financial and other terms that would apply to such rights. If the Company exercises its option to obtain Novartis-controlled rights to develop and commercialize a pre-filled syringe product in the United States, the Company will be obligated to either enter into a supply agreement with Novartis under which the Company will pay Novartis its manufacturing cost plus a specified percentage margin for supplies of Fovista products in pre-filled syringes that Novartis supplies to the Company, or obtain supplies of products in pre-filled syringes from a third party manufacturer and pay Novartis a low single-digit percentage of the Company's net sales of such products.

The Company has retained control over the design and execution of its pivotal Phase 3 clinical program for Fovista and remains responsible for funding the costs of that program, subject to Novartis's responsibility to provide Lucentis, an anti-VEGF drug to which Novartis has rights in the Novartis Territory, for use in the Phase 3 trials already initiated and in other Phase 2 and Phase 3 clinical trials in the Novartis Territory initiated following the effective date of the Novartis Agreement. Novartis will have control over, and will be responsible for the costs of, all other clinical trials that may be required to obtain marketing approvals in the Novartis Territory for licensed products under the agreement. Novartis is also responsible for costs associated with co-formulation development, pre-filled syringe development and other development costs in the Novartis Territory, excluding regulatory filing fees in the European Union for the standalone Fovista product, for which the Company will be responsible.

The Novartis Agreement, unless earlier terminated by the Company or Novartis, will expire upon the expiration of Novartis's obligation to pay the Company royalties on net sales of licensed products. The Company and Novartis each may terminate the Novartis Agreement if the other party materially breaches the agreement and does not cure such breach within a specified cure period, if the other party experiences any specified insolvency event, if the other party challenges or assists a third party in challenging the validity or enforceability of certain patent rights controlled by the terminating party, or if the parties are prevented in any manner that materially adversely affects the progression of the development or commercialization of licensed products for a specified period as a result of specified governmental actions. Novartis may terminate the Novartis Agreement at any time without cause, or within a specified period after a change in control of the Company, as defined in the Novartis Agreement, or for specified safety reasons, effective at the end of a specified period following Novartis's written notice to the Company of Novartis's election to terminate the agreement. The Company may also terminate the agreement if Novartis determines to seek marketing approval of an alternative anti-PDGF product in the Novartis Territory as more fully described below. If the Company elects to terminate the Novartis Agreement because specified governmental actions prevent the parties from materially progressing the development or commercialization of licensed products as described above, the Company will be required to pay a substantial termination fee. Following any termination, all rights to Fovista that the Company granted to Novartis, including, without limitation, the right to commercialize standalone Fovista products in the Novartis Territory, will revert to the Company, Novartis will perform specified activities in connection with transitioning to the Company the rights and responsibilities for the continued development, manufacture and commercialization of the standalone Fovista product for countries in the Novartis Territory, and the parties will cooperate on an orderly wind down of development and commercialization activities for other licensed products in the Novartis Territory.

Novartis has agreed to specified limitations on its ability to in-license, acquire or commercialize any anti-PDGF product that does not contain Fovista (an "Alternative Anti-PDGF Product") in the Novartis Territory and, to the extent Novartis develops, in-licenses or acquires such a product, to make such product available to the Company in the United States under specified option conditions. If the Company exercises its option, the Company will be obligated to make certain payments to Novartis, including specified milestone and royalty payments. The amounts of such payments will vary based on the product's stage of clinical development at the time the Company exercises its option, whether the product is a standalone or combination product and whether Novartis exercises an option to co-promote such product in the United States. If Novartis determines to seek marketing approval of an Alternative Anti-PDGF Product in the Novartis Territory, the Company will, subject to specified limitations, have the option to terminate the Novartis Agreement, convert Novartis's exclusive licenses into non-exclusive licenses, or elect to receive a royalty on sales of such product by Novartis. If the Company elects to terminate the Novartis Agreement, Novartis will, subject to specified limitations, be required to pay to the Company, certain payments based on achievement, with respect to such product, of the milestones that would have otherwise applied to licensed products under the Novartis Agreement.

Activities under the Novartis Agreement 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 Novartis Agreement includes the following deliverables: (1) an exclusive license to commercialize Fovista outside the United States (the "License Deliverable"); (2) the performance obligation to conduct research and development activities related to the Phase 3 Fovista clinical trials and certain Phase 2trials for Fovista (the "R&D Activity Deliverable"); (3) the performance obligation to supply API to Novartis for development and manufacturing purposes (the "Manufacturing Deliverable") and (4) the Company's obligation to participate on the joint operating committee established under the terms of the Novartis Agreement and related subcommittees (the "Joint Operating Committee Deliverable"). Novartis has the right, subject to certain approval rights of the Company, to sublicense the exclusive royalty-bearing license to commercialize Fovista in the Novartis Territory. The Company's obligation to provide access to clinical and regulatory information as part of the License Deliverable includes the obligation to provide access to all clinical data, regulatory filings, safety data and manufacturing data to Novartis which is necessary for the commercialization of Fovista in the Novartis Territory. The R&D Activity Deliverable includes the right and responsibility for the Company to conduct the Phase 3 Fovista clinical program and other studies of Fovista in the Novartis Territory which are necessary or desirable for regulatory approval or commercialization of Fovista. The Manufacturing Deliverable includes the obligation for the Company to supply API to Novartis for clinical purposes, for which Novartis has agreed to pay the Company’s manufacturing costs, and for commercial purposes, for which Novartis has agreed to pay the Company’s manufacturing costs plus a specified margin. The Joint Operating Committee Deliverable includes the obligation to participate in the Joint Operating Committee and related subcommittees at least through the first anniversary of regulatory approval in the European Union. 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 Novartis. Accordingly, each unit will be accounted for separately.

Options are considered substantive if, at the inception of the arrangement, the Company is at risk as to whether the collaboration partner will choose to exercise the option. Factors that the Company considers in evaluating whether an option is substantive include the overall objective of the arrangement, the benefit the collaborator might obtain from the arrangement without exercising the option, the cost to exercise the option and the likelihood that the option will be exercised. For arrangements under which an option is considered substantive, assuming the option is not priced at a significant and incremental discount, the Company does not consider the item underlying the option to be a deliverable at the inception of the arrangement and the associated option fees are not included in allocable arrangement consideration. Conversely, for arrangements under which an option is not considered substantive or if an option is priced at a significant and incremental discount, the Company would consider the item underlying the option to be a deliverable at the inception of the arrangement and a corresponding amount would be included in allocable arrangement consideration. All of the options included in the Novartis Agreement have been determined to be substantive, and none of the options are priced at a significant and incremental discount.

The Novartis Agreement provides that, if the Company elects to terminate the Novartis Agreement because specified governmental actions prevent the parties from materially progressing the development or commercialization of licensed products as described above, the Company will be required to pay a substantial termination fee. The Company has concluded that this termination provision constitutes a contingent event that was unknown at the inception of the agreement. As such, the Company has recorded the $200.0 million upfront payment in deferred revenue, long-term until such time that the contingency related to this termination provision is resolved. The Company believes the enrollment-based milestones and certain reimbursement milestones that may be achieved under the Novartis Agreement do not meet the recognition criteria within the definition of a milestone included in ASU 2010-17, Revenue Recognition—Milestone Method, and therefore, payments received for the achievement of the enrollment milestones in excess of the termination fee will be included in the allocable arrangement consideration and allocated to the deliverables based upon BESP using the relative selling price method.

The Company believes the marketing approval milestones that may be achieved under the Novartis Agreement are consistent with the definition of a milestone included in ASU 2010-17, Revenue Recognition—Milestone Method, and, accordingly, the Company will recognize payments related to the achievement of such milestones, if any, when the applicable milestone is achieved. Factors considered in this determination included scientific and regulatory risks that must be overcome to achieve each milestone, the level of effort and investment required to achieve each milestone, and the monetary value attributed to each milestone.

In May 2014, the Company received an upfront payment of $200.0 million in connection with its entry into the Novartis Agreement, which has not been recorded as revenue due to certain contingencies associated with the payment. In each of September 2014 and March 2015, the Company achieved a $50.0 million enrollment-based milestone, and in June 2016, the Company achieved a $30.0 million enrollment-based milestone, for an aggregate total of $130.0 million, under the Novartis Agreement. The Company uses the relative selling price method to allocate arrangement consideration to the Company's performance obligations under the Novartis Agreement. Below is a summary of the components of the Company's collaboration revenue for the years ended December 31, 2016, 2015, and 2014:



	Years ended December 31,
	2016		2015		2014
License revenue	$	22,937	$	38,083	$	38,373
Research and development activity revenue	9,741		8,378		2,000
API transfer revenue	18,212		5,020		883
Joint operating committee revenue	19		24		3
Total collaboration revenue	$	50,909	$	51,505	$	41,259

As of December 31, 2016, the Company had recorded total deferred revenue of approximately $210.0 million, $200.0 million of which relates to the upfront payment, with the remaining $10.0 million primarily attributable to the Company’s on-going performance obligations under the R&D Activity Deliverable.

Financing Agreement with Novo A/S	12 Months Ended
Financing Agreement with Novo A/S	Dec. 31, 2016
Related Party Transactions [Abstract]
Financing Agreement with Novo A/S	6. Financing Agreement with Novo A/S In May 2013, the Company entered into a Purchase and Sale Agreement with Novo A/S, which is referred to as the Novo Agreement, pursuant to which the Company had the ability to obtain financing in three tranches in an amount of up to $125.0 million in return for the sale to Novo A/S of aggregate royalties of worldwide sales of (a) Fovista, (b) Fovista-Related Products, and (c) Other Products (each as defined in the Novo Agreement), calculated as mid-single digit percentages of net sales. The Novo Agreement provided for up to three separate purchases for a purchase price of $41.7 million each, at a first, second and third closing, for an aggregate purchase price of $125.0 million. In each purchase, Novo A/S would acquire rights to a low single digit percentage of net sales. In each of May 2013, January 2014 and November 2014, the Company received cash payments of $41.7 million, or $125.0 million in the aggregate, and Novo A/S received, in the aggregate, a right to receive royalties on net sales of Fovista at a mid-single digit percentage. The royalty payment period covered by the Novo Agreement begins on commercial launch and ends, on a product-by-product and country-by-country basis, on the latest to occur of (i) the 12th anniversary of the commercial launch, (ii) the expiration of certain patent rights and (iii) the expiration of the regulatory exclusivity for each product in each country. Under the terms of the Novo Agreement, the Company is not required to reimburse or otherwise compensate Novo A/S through any means other than the agreed royalty entitlement. In addition, the Company does not, under the terms of the Novo Agreement, have the right or obligation to prepay Novo A/S in connection with a change of control of the Company or otherwise. The $125.0 million in aggregate proceeds from the three financing tranches under the Novo Agreement represents the full funding available under the Novo Agreement, and has been recorded as a liability on the Company's Balance Sheet as of December 31, 2016, in accordance with ASC 730, Research and Development. Because there is a significant related party relationship between the Company and Novo A/S, the Company is treating its obligation to make royalty payments under the Novo Agreement as an implicit obligation to repay the funds advanced by Novo A/S. As the Company makes royalty payments in accordance with the Novo Agreement, it will reduce the liability balance. At the time that such royalty payments become probable and estimable, and if such amounts exceed the liability balance, the Company will impute interest accordingly on a prospective basis based on such estimates. The Novo Agreement requires the establishment of a Joint Oversight Committee in the event that Novo A/S does not continue to have a representative on the Company's board of directors. The Joint Oversight Committee would have responsibilities that include "discussion and review" of all matters related to Fovista research, development, regulatory approval and commercialization, but there is no provision either implicit or explicit that gives the Joint Oversight Committee or its members decision-making authority.

Property and Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property and Equipment

7. Property and Equipment

Property and equipment as of December 31, 2016 and 2015 were as follows:



	Useful Life (Years)	December 31, 2016			December 31, 2015
Manufacturing and clinical equipment	7 - 10	$	617		$	617
Computer, software and other office equipment	5	1,711			944
Furniture and fixtures	7	774			738
Leasehold improvements	3 - 5	1,835			1,551
Construction-in-progress		—			515
		4,937			4,365
Accumulated depreciation		(1,656		)	(899		)
Property and equipment, net		$	3,281		$	3,466

For the years ended December 31, 2016, 2015 and 2014, depreciation expense was $757 thousand, $698 thousand and $127 thousand, respectively.

Income Taxes

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

8. Income Taxes

The Company utilizes the liability method of accounting for deferred income taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the carrying amounts and the tax basis of assets and liabilities. A valuation allowance is established against deferred tax assets when, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company's policy is to record interest and penalties on uncertain tax positions as income tax expense.

Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. A reconciliation of the statutory U.S. federal rate to the Company's effective tax rate is as follows:



	Years ended December 31,
	2016		2015		2014
Percent of pre-tax income:
U.S. federal statutory income tax rate	35.0	%	35.0	%	35.0	%
State taxes, net of federal benefit	2.8	%	7.4	%	6.8	%
Permanent items	(1.4	)%	(0.5	)%	2.3	%
Impact of state rate changes	(11.0	)%	0.9	%	—	%
Research and development credit	1.9	%	—	%	—	%
Other	1.1	%	—	%	—	%
Change in valuation allowance	(28.2	)%	(29.1	)%	(89.5	)%
Effective income tax rate	0.2	%	13.7	%	(45.4	)%

The components of income tax (benefit) expense are as follows:



	Years ended December 31,
	2016			2015			2014
Current:
Federal	$	(23,393	)	$	136		$	29,505
State	21			91			11,440
Deferred:
Federal	22,966			(17,014		)	(4,469		)
State	—			—			—
Income tax (benefit) expense	$	(406	)	$	(16,787	)	$	36,476

Significant components of the Company's deferred tax assets (liabilities) for 2016 and 2015 consist of the following:



	As of December 31,
	2016			2015
Deferred tax assets (liabilities)
Deferred revenue	$	125,634		$	142,675
License and technology payments	10,532			13,150
Share-based compensation	16,494			11,427
Accrued expenses	530			743
Depreciation	(651		)	(617		)
Federal and state net operating loss carryforwards	75,177			26,065
Excess tax benefits related to share-based compensation	—			1,630
Research and development credits	3,720			—
Other	2,155			5
Deferred income tax assets	233,591			195,078
Valuation allowance	(233,591		)	(171,965		)
Net deferred tax assets	$	—		$	23,113

In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible, and is impacted by the Company’s ability to carry back losses to 2014, the only year in which the Company had taxable income. The Company incurred tax losses in 2016. The Company realized its net deferred tax assets recorded as of December 31, 2015 in 2016 as a result of the Company’s carry back of its 2015 federal tax losses to 2014. The Company has carried forward its 2015 state tax losses due to various state restrictions on the use of carryback claims. The state NOLs are expected to begin to expire in 2027. Due to the Company’s history of losses and lack of other positive evidence to support taxable income after the 2014 tax year, the Company has recorded a valuation allowance against those remaining deferred tax assets that are not expected to be realized. As of December 31, 2016, the Company has federal NOLs carryforwards of approximately $187.4 million. These losses are due to expire in 2036.

For the years ended December 31, 2016 and 2015, the Company recorded a benefit from income taxes of $0.4 million and $16.8 million, respectively. The benefit from income taxes recorded in each period of 2016 and 2015 was based upon the Company’s estimated federal and state income tax liability for those respective years.

For the year ended December 31, 2016, the Company recorded an income tax benefit of $0.4 million related to unanticipated refunds received and the reduction in its valuation allowances to reflect the income tax associated with unrealized gains on available for sale securities recorded in other comprehensive income (loss). A corresponding income tax provision was also recorded in other comprehensive income (loss).

Pursuant to ASC 740, Income Taxes, the Company routinely evaluates the likelihood of success if challenged on income tax positions claimed on its income tax returns. During the year ended December 31, 2016, the Company reduced certain deferred tax assets by $3.8 million and reduced the corresponding valuation allowance by an equivalent amount. These items have not been recognized in the financial statements and if disallowed by the tax authorities, would not result in an adjustment to the Company’s effective tax rate, its balance sheet or its cash flow statements for the current year.

The Company's position with respect to uncertain tax positions is set forth below:



Opening balance	$	300
Gross amount of increases in unrecognized tax benefits during the period - current year provisions	—
Gross amount of increases in unrecognized tax benefits during the period - prior year provisions	3,828
Gross amount of increases in unrecognized tax benefits during the period - other	—
Decreases due to settlement with tax authorities during the period	—
Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period	—
Closing Balance	$	4,128

As the Company is currently being audited by the Internal Revenue Service and also anticipates an audit by the New York State Department of Taxation and Finance to occur during 2017, an estimate of unrecognized tax benefits that may be realized over the next twelve months cannot be determined at this time.

The Company will continue to evaluate its ability to realize its deferred tax assets on a periodic basis and will adjust such amounts in light of changing facts and circumstances including, but not limited to, future projections of taxable income, tax legislation, rulings by relevant tax authorities, the progress of ongoing tax audits and the regulatory approval of products currently under development. Any additional changes to the valuation allowance recorded on deferred tax assets in the future would impact the Company’s income taxes.

Operating Leases

12 Months Ended

Dec. 31, 2016

Leases [Abstract]

Operating Leases

9. Operating Leases

The Company leases office space located in Princeton, New Jersey and New York, New York under operating lease arrangements. The lease for the Company's principal Princeton office space expires in February 2018, whereas the lease for the Company's New York office space expires in January 2018. Future minimum rental commitments under non-cancelable operating leases in effect as of December 31, 2016, are as follows:



2017	$	4,316
2018	249
Total	$	4,565

Rent expense is calculated on the straight-line basis and amounted to $3.0 million, $2.1 million and $1.0 million for the years ended December 31, 2016, 2015 and 2014, respectively. In January 2017, the Company terminated its office leases in New York, NY and Princeton, NJ and made aggregate termination payments of approximately $2.1 million. The table above includes these termination payments, as well as the Company’s continuing rent obligations through February 2018.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

10. Commitments and Contingencies

Under various agreements, the Company may be required to pay royalties and make milestone payments. These agreements include the following:

•

Under the Company's divestiture agreement with OSI (Eyetech), Inc., which agreement is now held by OSI Pharmaceuticals, LLC., or OSI Pharmaceuticals, a subsidiary of Astellas US, LLC, for rights to particular anti-PDGF aptamers, including Fovista, the Company is obligated to pay to OSI Pharmaceuticals future one-time payments of $12.0 million in the aggregate upon marketing approval in the United States and the European Union of a covered anti-PDGF product. The Company is also obligated to pay to OSI Pharmaceuticals a royalty at a low single-digit percentage of net sales of any covered anti-PDGF product the Company successfully commercializes.

•

Under a license agreement with Archemix Corp., or Archemix, with respect to pharmaceutical products comprised of or derived from any anti-PDGF aptamer, the Company is obligated to make future payments to Archemix of up to an aggregate of $14.0 million if the Company achieves specified clinical and regulatory milestones with respect to Fovista, up to an aggregate of $3.0 million if the Company achieves specified commercial milestones with respect to Fovista and, for each other anti-PDGF aptamer product that it may develop under the agreement, up to an aggregate of approximately $18.8 million if the Company achieves specified clinical and regulatory milestones and up to an aggregate of $3.0 million if the Company achieves specified commercial milestones. No royalties are payable to Archemix under this license agreement.

•

Under a license agreement with Archemix with respect to pharmaceutical products comprised of or derived from anti-C5 aptamers, for each anti-C5 aptamer product that the Company may develop under the agreement, including Zimura, the Company is obligated to make future payments to Archemix of up to an aggregate of $57.5 million if the Company achieves specified development, clinical and regulatory milestones, and up to an aggregate of $22.5 million if the Company achieves specified commercial milestones. The Company is also obligated to pay Archemix a double-digit percentage of specified non-royalty payments the Company may receive from any sublicensee of the Company's rights under this license agreement. No royalties are payable to Archemix under this license agreement.

•

Under a license, manufacturing and supply agreement with Nektar Therapeutics, or Nektar, for specified pegylation reagents used to manufacture Fovista, the Company is obligated to make future payments to Nektar of up to an aggregate of $6.5 million if the Company achieves specified clinical and regulatory milestones, and an additional payment of $3.0 million if the Company achieves a specified commercial milestone with respect to Fovista. The Company is obligated to pay Nektar tiered royalties at low to mid-single-digit percentages of net sales of any licensed product the Company successfully commercializes, with the royalty percentage determined by the Company's level of licensed product sales, the extent of patent coverage for the licensed product and whether the Company has granted a third-party commercialization rights to the licensed product. In June 2014, the Company paid Nektar $19.8 million in connection with its entry into the Novartis Agreement.


•	Under the Novo Agreement, with respect to Fovista, the Company will be obligated to pay Novo A/S a mid-single-digit percentage royalty based on worldwide sales of Fovista. See "Note 6—Financing Agreement with Novo A/S" above for further information about Novo Agreement.

•

Under an option agreement with AVEO Pharmaceuticals relating to tivozanib, the Company was obligated to make milestone payments of $2.0 million upon the submission of an Investigational New Drug Application to the FDA and $6.0 million upon the earlier of demonstration of proof of concept in humans and a specified date in January 2017, subject to any exercise by the Company of its right to terminate the option agreement. In January 2017, the Company provided notice of termination of the Agreement, effective April 3, 2017.

The Company also has letter agreements with certain employees that require the funding of a specific level of payments, if certain events, such as a termination of employment in connection with a change in control or termination of employment by the employee for good reason or by the Company without cause, occur. For a description of these obligations, see the Company’s definitive proxy statement on Schedule 14A for the Company’s 2016 annual meeting of stockholders, as filed with the SEC on April 29, 2016.

In addition, in the course of normal business operations, the Company has agreements with contract service providers to assist in the performance of the Company’s research and development and manufacturing activities. Expenditures to CROs and CMOs represent significant costs in clinical development. Subject to required notice periods and the Company’s obligations under binding purchase orders, the Company can elect to discontinue the work under these agreements at any time.

Legal Proceedings

A purported class action lawsuit has been filed against the Company and certain of its current and former executive officers in the United States District Court for the Southern District of New York, captioned Frank Micholle et al. v. Ophthotech Corporation, et al., No. 1:17-cv-00210, filed on January 11, 2017. The complaint purports to be brought on behalf of shareholders who purchased the Company's common stock between May 11, 2015 and December 12, 2016. The complaint generally alleges that the Company and certain of its officers 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 prospects of the Company's Phase 3 trials for Fovista in combination with anti-VEGF drugs for the treatment of wet AMD. The complaint seeks equitable and/or injunctive relief, unspecified damages, attorneys’ fees, and other costs. The Company denies any allegations of wrongdoing and intend to vigorously defend against this lawsuit. The Company is unable, however, to predict the outcome of this matter at this time. Moreover, any conclusion of these matters in a manner adverse to the Company and for which it incurs substantial costs or damages not covered by the Company's directors’ and officers’ liability insurance would have a material adverse effect on its financial condition and business. In addition, the litigation could adversely impact the Company's reputation and divert management’s attention and resources from other priorities, including the execution of business plans and strategies that are important to the Company's ability to grow its business, any of which could have a material adverse effect on the Company's business.

Stock Option and Compensation Plans

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock Option and Compensation Plans

11. Stock Option and Compensation Plans

The Company adopted its 2007 Stock Incentive Plan (the "2007 Plan") for employees, non-employee directors and consultants for the purpose of advancing the interests of the Company's stockholders by enhancing its ability to attract, retain and motivate persons who are expected to make important contributions to the Company. The 2007 Plan provided for the granting of stock option awards, RSUs, and other stock-based and cash-based awards. Following the effectiveness of the 2013 Stock Incentive Plan described below in connection with the closing of the Company's initial public offering, the Company is no longer granting additional awards under the 2007 Plan.

In August 2013, the Company's board of directors adopted and the Company's stockholders approved the 2013 stock incentive plan (the "2013 Plan"), which became effective immediately prior to the closing of the Company's initial public offering. In June 2015, the Company’s board of directors adopted a first amendment to the 2013 Plan. The 2013 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, RSUs, restricted stock awards and other stock-based awards. Upon the effectiveness of the 2013 Plan, the number of shares of the Company's common stock that were reserved for issuance under the 2013 Plan was the sum of (1) such number of shares (up to approximately 3,359,641 shares) as is equal to the sum of 739,317 shares (the number of shares of the common stock then available for issuance under the 2007 Plan), and such number of shares of the Company's common stock that are subject to outstanding awards under the 2007 Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right plus (2) an annual increase, to be added the first business day of each fiscal year, beginning with the fiscal year ending December 31, 2014 and continuing until, and including, the fiscal year ending December 31, 2023, equal to the lowest of 2,542,372 shares of the Company's common stock, 4% of the number of shares of the Company's common stock outstanding on the first day of the fiscal year and an amount determined by its board of directors. The Company's employees, officers, directors, consultants and advisors are eligible to receive awards under the 2013 Plan. However, incentive stock options may only be granted to employees of the Company.

In connection with the evergreen provisions of the 2013 Plan, the number of shares available for issuance under the 2013 Plan was increased by approximately 1,257,000 shares, effective as of January 1, 2014, by approximately 1,360,000 shares, effective as of January 1, 2015, and by approximately 1,408,000 shares, effective as of January 1, 2016. As of December 31, 2016, the Company had approximately 1,028,000 shares available for grant under the 2013 Plan. In connection with the evergreen provisions of the 2013 Plan, the number of shares available for issuance under the 2013 Plan was further increased by approximately 1,429,000 shares, effective as of January 1, 2017.

In April 2016, the board of directors adopted the ESPP pursuant to which the Company may sell up to an aggregate of 1,000,000 shares of common stock. The ESPP was approved by the Company’s stockholders in June 2016. 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 offering period during the term of the ESPP. The first offering period began in September 2016.

A summary of the stock option activity, weighted average exercise prices, options outstanding and exercisable as of December 31, 2016, 2015 and 2014 is as follows:



	Years ended December 31,
	2016				2015				2014
	Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price
Outstanding, December 31, 2015	3,009		$	30.43	3,680		$	21.03	2,708		$	9.41
Granted	972		$	60.40	764		$	47.31	1,744		$	33.92
Exercised	(428	)	$	15.73	(1,133	)	$	10.31	(621	)	$	4.75
Expired or forfeited	(194	)	$	48.63	(302	)	$	34.09	(151	)	$	28.50
Outstanding, December 31, 2016	3,359		$	39.92	3,009		$	30.43	3,680		$	21.03



	Years ended December 31,
	2016	2015	2014
Options exercisable at December 31, 2016	1,531	955	993
Weighted average grant date fair value (per share) of options granted during the period	38.18	31.33	24.41

As of December 31, 2016, there were approximately 2,665,000 options outstanding, net of estimated forfeitures, that had vested or are expected to vest. The weighted-average exercise price of these options was $38.95 per option; the weighted-average remaining contractual life of these options was 7.5 years; and the aggregate intrinsic value of these options was approximately $0.3 million. A summary of the stock options outstanding and exercisable as of December 31, 2016 is as follows:



		December 31, 2016
		Options Outstanding			Options Exercisable
Range of Exercise Prices	Total Options Outstanding	Weighted Average Remaining Life (Years)	Weighted Average Exercise Price		Number Exercisable	Weighted Average Exercise Price
$0.12-$10.03	193	5.3	$	6.84	137	$	5.52
$10.04-$20.00	273	6.5	$	13.44	170	$	13.48
$20.01-$30.00	154	6.8	$	25.56	114	$	25.53
$30.01-$40.00	1,087	6.7	$	32.70	758	$	32.97
$40.01-$55.00	1,125	8.6	$	46.22	319	$	45.49
$55.01-$73.22	527	9.0	$	71.33	33	$	69.08
	3,359	7.6	$	39.92	1,531	$	31.19

Aggregate Intrinsic Value	254				254

Cash proceeds from, and the aggregate intrinsic value of, stock options exercised during the years ended December 31, 2016, 2015 and 2014, respectively, were as follows:



	Years ended December 31,
	2016		2015		2014
Cash proceeds from options exercised	$	6,934	$	11,473	$	2,949
Aggregate intrinsic value of options exercised	$	14,439	$	49,255	$	21,646

In connection with stock option awards granted to employees, the Company recognized approximately $22.8 million, $15.5 million and $11.3 million in share-based compensation expense during the years ended December 31, 2016, 2015 and 2014, respectively, net of expected forfeitures. As of December 31, 2016, there were approximately $25.1 million of unrecognized compensation costs, net of estimated forfeitures, related to stock option awards to granted employees, which are expected to be recognized over a remaining weighted average period of 2.3 years.

In connection with stock options awards granted to consultants, the Company recognized approximately $1.7 million, $4.1 million and $1.4 million in share-based compensation expense during the years ended December 31, 2016, 2015 and 2014, respectively, net of expected forfeitures. As of December 31, 2016, there were approximately $5.4 million of unrecognized compensation costs, net of estimated forfeitures, related to stock option awards granted to consultants, which are expected to be recognized over a remaining weighted average period of 2.5 years.

The following table presents a summary of the Company's outstanding shares of RSU awards granted as of December 31, 2016:



	Restricted Stock Units		Weighted Average Grant-Date Fair Value
Outstanding, December 31, 2015	288		$	44.54
Awarded	583		$	58.19
Vested	(109	)	$	43.88
Forfeited	(41	)	$	50.60
Outstanding, December 31, 2016	721		$	55.33

As of December 31, 2016, there were approximately 285,000 RSUs outstanding, net of estimated forfeitures, that are expected to vest. The weighted-average fair value of these RSUs was $56.07 per share; and the aggregate intrinsic value of these RSUs was approximately $1.4 million.

In connection with RSUs granted to employees, the Company recognized approximately $6.9 million, $5.2 million and $0.3 million in share-based compensation expense during the years ended December 31, 2016, 2015 and 2014, respectively, net of expected forfeitures. As of December 31, 2016, there was approximately $12.0 million of unrecognized compensation costs, net of estimated forfeitures, related to RSUs granted to employees, which are expected to be recognized over a remaining weighted average period of 2.9 years. The total fair value of the RSUs that vested during the year ended December 31, 2016 was $4.8 million.

In connection with the ESPP made available to employees, the Company recognized a de minimis amount of share-based compensation expense during the year ended December 31, 2016. The Company did not recognize any share-based compensation expense related to the ESPP during the years ended December 31, 2015 and 2014. As of December 31, 2016, there were approximately $0.1 million of unrecognized compensation costs, net of estimated forfeitures, related to the ESPP, which are expected to be recognized over 0.3 years.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plan	12. Employee Benefit Plan The Company maintains a defined contribution 401(k) plan available to employees. Employee contributions are voluntary and are determined on an individual basis, limited by the maximum amounts allowable under federal tax regulations. The Company's matching contributions to employees totaled approximately $0.8 million, $0.5 million and $0.2 million during the years ended December 31, 2016, 2015 and 2014, respectively.

Fair Value Measurements

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Fair Value Measurements

13. Fair Value Measurements

ASC 820, Fair Value Measurements and Disclosures, defines fair value as the price that would be received to sell an asset, or paid to transfer a liability, in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. The fair value standard also establishes a three-level hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.

The Company reviews investments on a periodic basis for other than temporary impairments. This review is subjective as it requires management to evaluate whether an event or change in circumstances has occurred in the period that may have a significant adverse effect on the fair value of the investment. The Company uses the market approach to measure fair value for its financial assets. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets. The Company classifies its corporate debt securities within the fair value hierarchy as Level 2 assets, as it primarily utilizes quoted market prices or rates for similar instruments to value these securities.

The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability on the measurement date. The three levels are defined as follows:


•	Level 1—inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market. The Company's Level 1 assets consist of investments in money market funds and U.S. Treasury securities.


•	Level 2—inputs to the valuation methodology include quoted prices for a similar asset or liability in an active market or model-derived valuations in which all significant inputs are observable for substantially the full term of the asset or liability. The Company's Level 2 assets consist of investments in investment-grade corporate debt securities.


•	Level 3—inputs to the valuation methodology are unobservable and significant to the fair value measurement of the asset or liability. The Company does not hold any assets that are measured using Level 3 inputs.

The following table presents, for each of the fair value hierarchy levels required under ASC 820, the Company's assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2016:



	Fair Value Measurement Using
	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets
Investments in money market funds*	$	108,096	$	—	$	—
Investments in U.S. Treasury securities	$	120,261	$	—	$	—
Investments in Corporate debt securities	$	—	$	35,087	$	—



	Fair Value Measurement Using
	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets
Investments in money market funds*	$	196,188	$	—	$	—
Investments in U.S. Treasury securities*	$	150,387	$	—	$	—
Investments in Corporate debt securities	$	—	$	39,833	$	—


*	Investments in money market funds, U.S. Treasury securities and corporate debt securities with maturities less than 90 days are reflected in cash and cash equivalents in the accompanying Balance Sheets.

No transfer of assets between Level 1 and Level 2 of the fair value measurement hierarchy occurred during the years ended December 31, 2016 or December 31, 2015.

Selected Quarterly Financial Information (unaudited)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Information (unaudited)

14. Selected Quarterly Financial Information (unaudited)

The following is a summary of the quarterly results of operations for the years ended December 31, 2016 and 2015:



	2016
	March 31			June 30			September 30			December 31
Collaboration revenue	$	15,721		$	28,198		$	1,668		$	5,322
Research and development expenses	37,770			48,262			50,854			59,409
General and administrative expenses	14,696			10,489			12,024			12,968
Loss from operations	(36,745		)	(30,553		)	(61,210		)	(67,055		)
Net loss attributable to common stockholders	$	(36,301	)	$	(29,945	)	$	(60,891	)	$	(66,283	)
Basic and diluted loss per common share	$	(1.03	)	$	(0.85	)	$	(1.71	)	$	(1.86	)



	2015
	March 31		June 30			September 30			December 31
Collaboration revenue	$	41,678	$	1,597		$	3,448		$	4,782
Research and development expenses	24,557		32,059			40,479			33,917
General and administrative expenses	9,584		11,959			10,412			12,066
Income (loss) from operations	7,537		(42,421		)	(47,443		)	(41,201		)
Net income (loss) attributable to common stockholders	$	6,636	$	(37,131	)	$	(39,573	)	$	(35,649	)
Basic earnings (loss) per common share	$	0.19	$	(1.08	)	$	(1.14	)	$	(1.02	)
Diluted earnings (loss) per common share	$	0.19	$	(1.08	)	$	(1.14	)	$	(1.02	)

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	15. Subsequent Events In December 2016, the Company announced that it had determined to implement a reduction in personnel to focus on an updated business plan. In January 2017, the Board of Directors approved a plan to implement a reduction in personnel is expected to involve approximately 80% of the Company’s workforce and is expected to be substantially complete during the first and second quarters of 2017. In connection with such reduction in personnel, the Company estimates that it will incur approximately $14.4 million of pre-tax charges during the first and second quarters of 2017, of which approximately $13.8 million is expected to result in future cash expenditures. These pre-tax charges relate to (a) expected severance and other employee costs of approximately $12.3 million and (b) expected lease termination costs of approximately $2.1 million. The Company expects to realize estimated annualized cost savings from the reduction in personnel in the range of $25 million to $30 million starting in the third quarter of 2017.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Basis of Presentation

Segment and Geographic Information

Segment and geographic information

Use of Estimates

Cash and Cash Equivalents

Available for Sale Securities

Revenue Recognition

Collaboration Revenue



	Years ended December 31,
	2016		2015		2014
License revenue	$	22,937	$	38,083	$	38,373
Research and development activity revenue	9,741		8,378		2,000
API transfer revenue	18,212		5,020		883
Joint operating committee revenue	19		24		3
Total collaboration revenue	$	50,909	$	51,505	$	41,259

Concentration of Credit Risk

Concentration of Suppliers

Foreign Currency Translation

Financial Instruments

Property and Equipment

Research and Development


•	external research and development expenses incurred under arrangements with third parties, such as contract research organizations ("CROs") and other vendors and contract manufacturing organizations ("CMOs") for the production of drug substance and drug product; and


•	employee-related expenses, including salaries, benefits and share-based compensation expense.

Income Taxes

Share-Based Compensation

Stock Options



	Years ended December 31,
	2016	2015	2014
Expected common stock price volatility	71%	72%	82%
Risk-free interest rate	1.14% - 2.37%	1.35% - 2.24%	1.61% - 2.13%
Expected term of options (years)	6.1	6.2	6.2
Expected dividend yield	—	—	—

RSUs

The Company estimates the fair value of RSUs granted to employees using the closing market price of the Company's common stock on the date of grant.

ESPP

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Schedule of collaboration revenue components

Below is a summary of the components of the Company's collaboration revenue for the years ended December 2016, 2015 and 2014:



	Years ended December 31,
	2016		2015		2014
License revenue	$	22,937	$	38,083	$	38,373
Research and development activity revenue	9,741		8,378		2,000
API transfer revenue	18,212		5,020		883
Joint operating committee revenue	19		24		3
Total collaboration revenue	$	50,909	$	51,505	$	41,259

Schedule of weighted-average assumptions used to estimate grant date fair value of stock options



	Years ended December 31,
	2016	2015	2014
Expected common stock price volatility	71%	72%	82%
Risk-free interest rate	1.14% - 2.37%	1.35% - 2.24%	1.61% - 2.13%
Expected term of options (years)	6.1	6.2	6.2
Expected dividend yield	—	—	—

Schedule of share-based compensation expense



	Years ended December 31,
	2016		2015		2014
Research and development	$	21,380	$	16,608	$	7,594
General and administrative	10,280		8,152		5,446
Total	$	31,660	$	24,760	$	13,040

Net Loss Per Common Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

Schedule of computation of basic and diluted net income (loss) per common share

The following table sets forth the computation of basic and diluted net income (loss) per common share for the periods indicated:



	Years ended December 31,
	2016			2015			2014
Basic and diluted net loss per common share calculation:
Net loss	$	(193,420	)	$	(105,717	)	$	(116,772	)
Weighted average common shares outstanding	35,486			34,580			33,258
Net loss per common share—basic and diluted	$	(5.45	)	$	(3.06	)	$	(3.51	)

Schedule of potentially dilutive securities that have been excluded from the computations of diluted weighted average common shares outstanding

The following potentially dilutive securities have been excluded from the computations of diluted weighted average common shares outstanding for the periods presented, as they would be anti-dilutive:



	Years ended December 31,
	2016	2015	2014
Stock options outstanding	3,359	3,009	3,680
Restricted stock units	721	288	37
Warrants	—	—	14
Total	4,080	3,297	3,731

Cash, Cash Equivalents and Available for Sale Securities (Tables)

12 Months Ended

Dec. 31, 2016

Cash, Cash Equivalents, and Short-term Investments [Abstract]

Summary of available for sale securities, including carrying value and estimated fair values

Available for sale securities, including carrying value and estimated fair values, are summarized as follows:



	As of December 31, 2016
	Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury securities	$	120,288	$	6	$	(33	)	$	120,261
Corporate debt securities	35,114		—		(27		)	35,087
Total	$	155,402	$	6	$	(60	)	$	155,348



	As of December 31, 2015
	Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury securities	$	130,507	$	—	$	(311	)	$	130,196
Corporate debt securities	39,995		—		(162		)	39,833
Total	$	170,502	$	—	$	(473	)	$	170,029

Schedule of changes in accumulated other comprehensive income (loss) associated with the unrealized loss on available for sale securities

The changes in accumulated other comprehensive income (loss) associated with the unrealized gain (loss) on available for sale securities for the years ended December 31, 2016 and December 31, 2015 were as follows:



	Years ended December 31,
	2016			2015
Beginning balance	$	(473	)	$	(65	)
Current period changes in fair value before reclassifications, net of tax	261			(351		)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	—			(57		)
Total other comprehensive income (loss)	261			(408		)
Ending balance	$	(212	)	$	(473	)

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Licensing and Commercialization Agreement with Novartis Pharma AG (Tables)

12 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of collaboration revenue components

Below is a summary of the components of the Company's collaboration revenue for the years ended December 31, 2016, 2015, and 2014:



	Years ended December 31,
	2016		2015		2014
License revenue	$	22,937	$	38,083	$	38,373
Research and development activity revenue	9,741		8,378		2,000
API transfer revenue	18,212		5,020		883
Joint operating committee revenue	19		24		3
Total collaboration revenue	$	50,909	$	51,505	$	41,259

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Schedule of property and equipment

Property and equipment as of December 31, 2016 and 2015 were as follows:



	Useful Life (Years)	December 31, 2016			December 31, 2015
Manufacturing and clinical equipment	7 - 10	$	617		$	617
Computer, software and other office equipment	5	1,711			944
Furniture and fixtures	7	774			738
Leasehold improvements	3 - 5	1,835			1,551
Construction-in-progress		—			515
		4,937			4,365
Accumulated depreciation		(1,656		)	(899		)
Property and equipment, net		$	3,281		$	3,466

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of reconciliation of the statutory U.S. federal rate to the Company's effective tax rate

A reconciliation of the statutory U.S. federal rate to the Company's effective tax rate is as follows:



	Years ended December 31,
	2016		2015		2014
Percent of pre-tax income:
U.S. federal statutory income tax rate	35.0	%	35.0	%	35.0	%
State taxes, net of federal benefit	2.8	%	7.4	%	6.8	%
Permanent items	(1.4	)%	(0.5	)%	2.3	%
Impact of state rate changes	(11.0	)%	0.9	%	—	%
Research and development credit	1.9	%	—	%	—	%
Other	1.1	%	—	%	—	%
Change in valuation allowance	(28.2	)%	(29.1	)%	(89.5	)%
Effective income tax rate	0.2	%	13.7	%	(45.4	)%

Schedule of components of income tax (benefit) expense

The components of income tax (benefit) expense are as follows:



	Years ended December 31,
	2016			2015			2014
Current:
Federal	$	(23,393	)	$	136		$	29,505
State	21			91			11,440
Deferred:
Federal	22,966			(17,014		)	(4,469		)
State	—			—			—
Income tax (benefit) expense	$	(406	)	$	(16,787	)	$	36,476

Schedule of significant components of the Company's deferred tax assets (liabilities)

Significant components of the Company's deferred tax assets (liabilities) for 2016 and 2015 consist of the following:



	As of December 31,
	2016			2015
Deferred tax assets (liabilities)
Deferred revenue	$	125,634		$	142,675
License and technology payments	10,532			13,150
Share-based compensation	16,494			11,427
Accrued expenses	530			743
Depreciation	(651		)	(617		)
Federal and state net operating loss carryforwards	75,177			26,065
Excess tax benefits related to share-based compensation	—			1,630
Research and development credits	3,720			—
Other	2,155			5
Deferred income tax assets	233,591			195,078
Valuation allowance	(233,591		)	(171,965		)
Net deferred tax assets	$	—		$	23,113

Schedule of position with respect to uncertain tax positions

The Company's position with respect to uncertain tax positions is set forth below:



Opening balance	$	300
Gross amount of increases in unrecognized tax benefits during the period - current year provisions	—
Gross amount of increases in unrecognized tax benefits during the period - prior year provisions	3,828
Gross amount of increases in unrecognized tax benefits during the period - other	—
Decreases due to settlement with tax authorities during the period	—
Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period	—
Closing Balance	$	4,128

Operating Leases (Tables)

12 Months Ended

Dec. 31, 2016

Leases [Abstract]

Schedule of future minimum rental commitments under non-cancelable operating leases

Future minimum rental commitments under non-cancelable operating leases in effect as of December 31, 2016, are as follows:



2017	$	4,316
2018	249
Total	$	4,565

Stock Option and Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of the stock option activity including weighted average exercise prices, options outstanding and exercisable

A summary of the stock option activity, weighted average exercise prices, options outstanding and exercisable as of December 31, 2016, 2015 and 2014 is as follows:



	Years ended December 31,
	2016				2015				2014
	Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price
Outstanding, December 31, 2015	3,009		$	30.43	3,680		$	21.03	2,708		$	9.41
Granted	972		$	60.40	764		$	47.31	1,744		$	33.92
Exercised	(428	)	$	15.73	(1,133	)	$	10.31	(621	)	$	4.75
Expired or forfeited	(194	)	$	48.63	(302	)	$	34.09	(151	)	$	28.50
Outstanding, December 31, 2016	3,359		$	39.92	3,009		$	30.43	3,680		$	21.03



	Years ended December 31,
	2016	2015	2014
Options exercisable at December 31, 2016	1,531	955	993
Weighted average grant date fair value (per share) of options granted during the period	38.18	31.33	24.41

Summary of the stock options outstanding and exercisable

A summary of the stock options outstanding and exercisable as of December 31, 2016 is as follows:



		December 31, 2016
		Options Outstanding			Options Exercisable
Range of Exercise Prices	Total Options Outstanding	Weighted Average Remaining Life (Years)	Weighted Average Exercise Price		Number Exercisable	Weighted Average Exercise Price
$0.12-$10.03	193	5.3	$	6.84	137	$	5.52
$10.04-$20.00	273	6.5	$	13.44	170	$	13.48
$20.01-$30.00	154	6.8	$	25.56	114	$	25.53
$30.01-$40.00	1,087	6.7	$	32.70	758	$	32.97
$40.01-$55.00	1,125	8.6	$	46.22	319	$	45.49
$55.01-$73.22	527	9.0	$	71.33	33	$	69.08
	3,359	7.6	$	39.92	1,531	$	31.19

Aggregate Intrinsic Value	254				254

Schedule of cash proceeds from, and the aggregate intrinsic value of, stock options exercised

Cash proceeds from, and the aggregate intrinsic value of, stock options exercised during the years ended December 31, 2016, 2015 and 2014, respectively, were as follows:



	Years ended December 31,
	2016		2015		2014
Cash proceeds from options exercised	$	6,934	$	11,473	$	2,949
Aggregate intrinsic value of options exercised	$	14,439	$	49,255	$	21,646

Summary of the Company's outstanding shares of RSU awards

The following table presents a summary of the Company's outstanding shares of RSU awards granted as of December 31, 2016:



	Restricted Stock Units		Weighted Average Grant-Date Fair Value
Outstanding, December 31, 2015	288		$	44.54
Awarded	583		$	58.19
Vested	(109	)	$	43.88
Forfeited	(41	)	$	50.60
Outstanding, December 31, 2016	721		$	55.33

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of the Company's assets and liabilities that are measured at fair value on a recurring basis



	Fair Value Measurement Using
	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets
Investments in money market funds*	$	108,096	$	—	$	—
Investments in U.S. Treasury securities	$	120,261	$	—	$	—
Investments in Corporate debt securities	$	—	$	35,087	$	—



	Fair Value Measurement Using
	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets
Investments in money market funds*	$	196,188	$	—	$	—
Investments in U.S. Treasury securities*	$	150,387	$	—	$	—
Investments in Corporate debt securities	$	—	$	39,833	$	—


*	Investments in money market funds, U.S. Treasury securities and corporate debt securities with maturities less than 90 days are reflected in cash and cash equivalents in the accompanying Balance Sheets.

Selected Quarterly Financial Information (unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Summary of the quarterly results of operations

The following is a summary of the quarterly results of operations for the years ended December 31, 2016 and 2015:



	2016
	March 31			June 30			September 30			December 31
Collaboration revenue	$	15,721		$	28,198		$	1,668		$	5,322
Research and development expenses	37,770			48,262			50,854			59,409
General and administrative expenses	14,696			10,489			12,024			12,968
Loss from operations	(36,745		)	(30,553		)	(61,210		)	(67,055		)
Net loss attributable to common stockholders	$	(36,301	)	$	(29,945	)	$	(60,891	)	$	(66,283	)
Basic and diluted loss per common share	$	(1.03	)	$	(0.85	)	$	(1.71	)	$	(1.86	)



	2015
	March 31		June 30			September 30			December 31
Collaboration revenue	$	41,678	$	1,597		$	3,448		$	4,782
Research and development expenses	24,557		32,059			40,479			33,917
General and administrative expenses	9,584		11,959			10,412			12,066
Income (loss) from operations	7,537		(42,421		)	(47,443		)	(41,201		)
Net income (loss) attributable to common stockholders	$	6,636	$	(37,131	)	$	(39,573	)	$	(35,649	)
Basic earnings (loss) per common share	$	0.19	$	(1.08	)	$	(1.14	)	$	(1.02	)
Diluted earnings (loss) per common share	$	0.19	$	(1.08	)	$	(1.14	)	$	(1.02	)

Business (Details)	Dec. 31, 2016 trial
Phase 3 Clinical Trials Failure to Meet Primary Endpoint
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of trials completed	2
Phase 3 Clinical Trial
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of trials completed	3

Summary of Significant Accounting Policies - Segment and Geographic Information (Details)	12 Months Ended
	Dec. 31, 2016 segment
Accounting Policies [Abstract]
Number of operating segments	1
Number of reporting segments	1

Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) $ in Millions	Dec. 31, 2016 USD ($)
Accounting Policies [Abstract]
Cash, cash equivalents and available for sale securities	$ 289.3

- Definition

Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

+ References + Details

Summary of Significant Accounting Policies - Collaboration Revenue (Detail) $ in Thousands	1 Months Ended				3 Months Ended								12 Months Ended			22 Months Ended
	Jun. 30, 2016 USD ($)	Mar. 31, 2015 USD ($)	Sep. 30, 2014 USD ($)	May 31, 2014 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) category	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2016 USD ($)
Components of collaboration revenue
Total collaboration revenue					$ 5,322	$ 1,668	$ 28,198	$ 15,721	$ 4,782	$ 3,448	$ 1,597	$ 41,678	$ 50,909	$ 51,505	$ 41,259
Number of categories for milestones \| category													3
License revenue
Components of collaboration revenue
Total collaboration revenue													$ 22,937	38,083	38,373
Research and development activity revenue
Components of collaboration revenue
Total collaboration revenue													9,741	8,378	2,000
API transfer revenue
Components of collaboration revenue
Total collaboration revenue													18,212	5,020	883
Joint operating committee revenue
Components of collaboration revenue
Total collaboration revenue													$ 19	$ 24	$ 3
Novartis Pharma AG \| Licensing and Commercialization Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront fees received				$ 200,000
Novartis Pharma AG \| Licensing and Commercialization Agreement \| Achievement of specified patient enrollment milestones
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Patient enrollment-based milestone revenue achieved	$ 30,000	$ 50,000	$ 50,000													$ 130,000
Milestone payment received																$ 130,000

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2016
Minimum
Property and equipment
Estimated useful lives	3 years
Maximum
Property and equipment
Estimated useful lives	10 years

Summary of Significant Accounting Policies - Schedule of Weighted-Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected common stock price volatility	71.00%	72.00%	82.00%
Risk-free interest rate, minimum	1.14%	1.35%	1.61%
Risk-free interest rate, maximum	2.37%	2.24%	2.13%
Expected term of options (years)	6 years 1 month 6 days	6 years 2 months 12 days	6 years 2 months 12 days
Expected dividend yield	0.00%	0.00%	0.00%

Summary of Significant Accounting Policies - Share-Based Compensation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Apr. 30, 2016
Accounting Policies [Abstract]
Expected dividend yield	0.00%
Share-Based Compensation
Share-based compensation expense	$ 31,660,000	$ 24,760,000	$ 13,040,000
Research and development
Share-Based Compensation
Share-based compensation expense	21,380,000	16,608,000	7,594,000
General and administrative
Share-Based Compensation
Share-based compensation expense	10,280,000	8,152,000	5,446,000
ESPP
Share-Based Compensation
Share-based compensation expense	$ 0	$ 0	$ 0
ESPP \| Maximum
Share-Based Compensation
Number of shares reserved for issuance under the Plan (in shares)				1,000,000

Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Basic and diluted net loss per common share calculation:
Net loss					$ (193,420)	$ (105,717)	$ (116,772)
Weighted average common shares outstanding (in shares)					35,486	34,580	33,258
Net loss per common share - basic and diluted (in dollars per share)	$ (1.86)	$ (1.71)	$ (0.85)	$ (1.03)	$ (5.45)	$ (3.06)	$ (3.51)
Anti-dilutive securities
Total (in shares)					4,080	3,297	3,731
Stock options outstanding
Anti-dilutive securities
Total (in shares)					3,359	3,009	3,680
Restricted stock units
Anti-dilutive securities
Total (in shares)					721	288	37
Warrants
Anti-dilutive securities
Total (in shares)					0	0	14

Cash, Cash Equivalents and Available for Sale Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash	$ 25,800,000	$ 5,500,000
Investments in money market funds, U.S. Treasury securities and certain short-term investment-grade corporate debt securities with original maturities of 90 days or less	108,100,000	216,400,000
Fair Value	155,348,000	170,029,000
Available for sale securities with maturities of less than one year	155,348,000	74,731,000
Available for sale securities with maturities of greater than one year	0	$ 95,298,000
Other than temporary losses in fair value, available for sale securities	$ 0

- Definition

Investments in debt and equity securities which are categorized neither as held-to-maturity nor trading and which are intended to be sold or mature more than one year from the balance sheet date or operating cycle, if longer. Such securities are reported at fair value; unrealized gains (losses) related to Available-for-sale Securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain (loss) of an Available-for-sale security that is designated as being hedged in a fair value hedge is recognized in earnings during the period of the hedge, as are other than temporary declines in fair value below the cost basis for investments in equity securities and debt securities that an entity intends to sell or it is more likely than not that it will be required to sell before the recovery of its amortized cost basis. Other than temporary declines in fair value below the cost basis for debt securities categorized as Available-for-sale that an entity does not intend to sell and for which it is not more likely than not that the entity will be required to sell before the recovery of its amortized cost basis are bifurcated into credit losses and losses related to all other factors. Other than temporary declines in fair value below cost basis related to credit losses are recognized in earnings, and losses related to all other factors are recognized in other comprehensive income.

+ References + Details

Cash, Cash Equivalents and Available for Sale Securities - Summary of Available for Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 155,402	$ 170,502
Unrealized Gains	6	0
Unrealized Losses	(60)	(473)
Fair Value	155,348	170,029
U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Cost	120,288	130,507
Unrealized Gains	6	0
Unrealized Losses	(33)	(311)
Fair Value	120,261	130,196
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Cost	35,114	39,995
Unrealized Gains	0	0
Unrealized Losses	(27)	(162)
Fair Value	$ 35,087	$ 39,833

Cash, Cash Equivalents and Available for Sale Securities - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (94,618)	$ 59,947	$ 128,537	$ 169,720
Current period changes in fair value before reclassifications, net of tax	261	(351)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0	(57)
Other comprehensive income (loss)	261	(408)	(65)
Ending balance	(94,618)	59,947	128,537
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(212)	(473)	(65)	$ 0
Ending balance	$ (212)	$ (473)	$ (65)

Licensing and Commercialization Agreement with Novartis Pharma AG (Details) $ in Thousands	1 Months Ended				3 Months Ended								12 Months Ended			22 Months Ended
	Jun. 30, 2016 USD ($)	Mar. 31, 2015 USD ($)	Sep. 30, 2014 USD ($)	May 31, 2014 USD ($) milestone	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2016 USD ($)
Agreement
Total collaboration revenue					$ 5,322	$ 1,668	$ 28,198	$ 15,721	$ 4,782	$ 3,448	$ 1,597	$ 41,678	$ 50,909	$ 51,505	$ 41,259
License revenue
Agreement
Total collaboration revenue													22,937	38,083	38,373
Research and development activity revenue
Agreement
Total collaboration revenue													9,741	8,378	2,000
API transfer revenue
Agreement
Total collaboration revenue													18,212	5,020	883
Joint operating committee revenue
Agreement
Total collaboration revenue													19	$ 24	$ 3
Licensing and Commercialization Agreement \| Novartis Pharma AG
Agreement
Upfront fees received				$ 200,000
Licensing and Commercialization Agreement \| Novartis Pharma AG \| Research and development activity revenue
Agreement
Deferred revenue					210,000								210,000
Licensing and Commercialization Agreement \| Novartis Pharma AG \| Research and development activity revenue \| Up-front payment
Agreement
Deferred revenue					200,000								200,000
Licensing and Commercialization Agreement \| Novartis Pharma AG \| Research and development activity revenue \| Ongoing performance obligations
Agreement
Deferred revenue					$ 10,000								$ 10,000
Licensing and Commercialization Agreement \| Novartis Pharma AG \| Achievement of specified patient enrollment milestones
Agreement
Number of milestones \| milestone				2
Patient enrollment-based milestone revenue achieved	$ 30,000	$ 50,000	$ 50,000													$ 130,000
Licensing and Commercialization Agreement \| Novartis Pharma AG \| Achievement of specified patient enrollment milestones \| Maximum
Agreement
Aggregate amount receivable on achievement of milestone				$ 50,000
Licensing and Commercialization Agreement \| Novartis Pharma AG \| Achievement of specified regulatory approval milestones \| Maximum
Agreement
Aggregate amount receivable on achievement of milestone				300,000
Licensing and Commercialization Agreement \| Novartis Pharma AG \| Achievement of specified commercial sale milestone \| Maximum
Agreement
Aggregate amount receivable on achievement of milestone				$ 400,000

Financing Agreement with Novo A/S (Details)	1 Months Ended			12 Months Ended			19 Months Ended
Financing Agreement with Novo A/S (Details)	Nov. 30, 2014 USD ($)	Jan. 31, 2014 USD ($)	May 31, 2013 USD ($) tranche purchase	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Nov. 30, 2014 USD ($)
Agreement
Proceeds from royalty purchase agreement				$ 0	$ 0	$ 83,333,000
Royalty purchase liability				$ 125,000,000	$ 125,000,000
Novo A/S \| Novo Agreement \| Fovista, Fovista-Related Products, and Other Products
Agreement
Number of tranches in financing \| tranche			3
Aggregate royalty rights			$ 125,000,000.0
Number of separate purchases provided for in financing agreement \| purchase			3
Proceeds from royalty purchase agreement	$ 41,700,000	$ 41,700,000	$ 41,700,000				$ 125,000,000
Royalty purchase liability			$ 125,000,000

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property and Equipment
Property and equipment, gross	$ 4,937	$ 4,365
Accumulated depreciation	(1,656)	(899)
Property and equipment, net	3,281	3,466
Depreciation expense	$ 757	698	$ 127
Minimum
Property and Equipment
Useful life	3 years
Maximum
Property and Equipment
Useful life	10 years
Manufacturing and clinical equipment
Property and Equipment
Property and equipment, gross	$ 617	617
Manufacturing and clinical equipment \| Minimum
Property and Equipment
Useful life	7 years
Manufacturing and clinical equipment \| Maximum
Property and Equipment
Useful life	10 years
Computer, software and other office equipment
Property and Equipment
Useful life	5 years
Property and equipment, gross	$ 1,711	944
Furniture and fixtures
Property and Equipment
Useful life	7 years
Property and equipment, gross	$ 774	738
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 1,835	1,551
Leasehold improvements \| Minimum
Property and Equipment
Useful life	3 years
Leasehold improvements \| Maximum
Property and Equipment
Useful life	5 years
Construction-in-progress
Property and Equipment
Property and equipment, gross	$ 0	$ 515

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Percent of pre-tax income:
U.S. federal statutory income tax rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	2.80%	7.40%	6.80%
Permanent items	(1.40%)	(0.50%)	2.30%
Impact of state rate changes	(11.00%)	0.90%	0.00%
Research and development credit	1.90%	(0.00%)	(0.00%)
Other	1.10%	0.00%	0.00%
Change in valuation allowance	(28.20%)	(29.10%)	(89.50%)
Effective income tax rate	0.20%	13.70%	(45.40%)

Income Taxes - Schedule of Components of Income Tax (Benefit) Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ (23,393)	$ 136	$ 29,505
State	21	91	11,440
Deferred:
Federal	22,966	(17,014)	(4,469)
State	0	0	0
Income tax (benefit) expense	$ (406)	$ (16,787)	$ 36,476

Income Taxes - Schedule of Significant Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets (liabilities)
Deferred revenue	$ 125,634	$ 142,675
License and technology payments	10,532	13,150
Share-based compensation	16,494	11,427
Accrued expenses	530	743
Depreciation	(651)	(617)
Federal and state net operating loss carryforwards	75,177	26,065
Excess tax benefits related to share-based compensation	0	1,630
Research and development credits	3,720	0
Other	2,155	5
Deferred income tax assets	233,591	195,078
Valuation allowance	(233,591)	(171,965)
Net deferred tax assets	$ 0	$ 23,113

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Federal and state tax liability, benefit from income taxes	$ 0.4	$ 16.8
Income tax benefit	0.4
Reduction in deferred tax assets and corresponding valuation allowance	3.8
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Federal net operating loss carryforwards	$ 187.4

Income Taxes - Schedule of Position with Respect to Uncertain Tax Positions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Opening balance	$ 300
Gross amount of increases in unrecognized tax benefits during the period - current year provisions	0
Gross amount of increases in unrecognized tax benefits during the period - prior year provisions	3,828
Gross amount of increases in unrecognized tax benefits during the period - other	0
Decreases due to settlement with tax authorities during the period	0
Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period	0
Closing Balance	$ 4,128

Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 31, 2017
Future minimum rental commitments under non-cancelable operating leases
2017	$ 4,316
2018	249
Total	4,565
Rent expense	$ 3,000	$ 2,100	$ 1,000
Subsequent Event \| Lease Termination
Restructuring Cost and Reserve [Line Items]
Aggregate termination payments				$ 2,100

Commitments and Contingencies (Details) - USD ($) $ in Millions	1 Months Ended
	Jun. 30, 2014	Dec. 31, 2016
AVEO \| Tivozanib \| Submission of Investigational New Drug application
Commitments and contingencies
Amount to be paid on achievement of milestone		$ 2.0
AVEO \| Tivozanib \| Demonstration of proof of concept in humans
Commitments and contingencies
Amount to be paid on achievement of milestone		6.0
Acquisition agreement \| OSI Pharmaceuticals \| PDGF Licensed Products
Commitments and contingencies
Amount to be paid on achievement of milestone		12.0
License Agreements \| Archemix \| PDGF Licensed Products
Commitments and contingencies
Royalty payable		0.0
License Agreements \| Archemix \| Fovista \| Achievement of specified clinical and regulatory milestones \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone		14.0
License Agreements \| Archemix \| Fovista \| Achievement of specified commercial milestones \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone		3.0
License Agreements \| Archemix \| Other anti-PDGF aptamer \| Achievement of specified clinical and regulatory milestones \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone		18.8
License Agreements \| Archemix \| Other anti-PDGF aptamer \| Achievement of specified commercial milestones \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone		3.0
License Agreements \| Archemix \| C5 Licensed Product
Commitments and contingencies
Royalty payable		0.0
License Agreements \| Archemix \| C5 Licensed Product \| Achievement of specified commercial milestones \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone		22.5
License Agreements \| Archemix \| C5 Licensed Product \| Achievement of specified development, clinical and regulatory milestones \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone		57.5
Supply Agreement \| Nektar
Commitments and contingencies
Payment upon entry into Novartis Agreement	$ 19.8
Supply Agreement \| Nektar \| Fovista \| Achievement of specified clinical and regulatory milestones \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone		6.5
Supply Agreement \| Nektar \| Fovista \| Achievement of specified commercial milestones
Commitments and contingencies
Amount to be paid on achievement of milestone		$ 3.0

Stock Option and Compensation Plans (Details) - USD ($)					1 Months Ended		12 Months Ended
Stock Option and Compensation Plans (Details) - USD ($)	Jan. 01, 2017	Jan. 01, 2016	Jan. 01, 2015	Jan. 01, 2014	Apr. 30, 2016	Aug. 31, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock Option and Compensation Plans
Options outstanding (in shares)							2,665,000
Weighted-average exercise price of options (in dollars per share)							$ 38.95
Weighted-average remaining contractual life of options							7 years 6 months
Aggregate intrinsic value of options outstanding							$ 300,000
Share-based compensation expense							31,660,000	$ 24,760,000	$ 13,040,000
ESPP
Stock Option and Compensation Plans
Purchase price of common stock as percentage of fair market value					85.00%
Share-based compensation expense							$ 0	0	0
Expected weighted average period to recognize share-based compensation costs							3 months
Unrecognized compensation costs, net of estimated forfeitures							$ 100,000
Restricted stock units
Stock Option and Compensation Plans
RSUs expected to vest (in shares)							285,000
Weighted-average fair value of RSUs expected to vest (in dollars per share)							$ 56.07
Aggregate intrinsic value of RSUs expected to vest							$ 1,400,000
Total fair value vested							4,800,000
Employees \| Stock options
Stock Option and Compensation Plans
Share-based compensation expense							22,800,000	15,500,000	11,300,000
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures							$ 25,100,000
Expected weighted average period to recognize share-based compensation costs							2 years 3 months 18 days
Employees \| Restricted stock units
Stock Option and Compensation Plans
Share-based compensation expense							$ 6,900,000	5,200,000	300,000
Expected weighted average period to recognize share-based compensation costs							2 years 10 months 24 days
Unrecognized compensation costs, net of estimated forfeitures							$ 12,000,000
Consultants \| Non-employee Options
Stock Option and Compensation Plans
Share-based compensation expense							1,700,000	$ 4,100,000	$ 1,400,000
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures							$ 5,400,000
Expected weighted average period to recognize share-based compensation costs							2 years 6 months
Maximum \| ESPP
Stock Option and Compensation Plans
Number of shares reserved for issuance under the Plan (in shares)					1,000,000
2007 Plan
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan (in shares)						739,317
2013 Plan
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan (in shares)							1,028,000
Annual increase in shares reserved for issuance under the Plan (in shares)						2,542,372
Annual increase in shares reserved for issuance under the Plan (as a percent)						4.00%
Increase in number of shares available under the Plan (in shares)		1,408,000	1,360,000	1,257,000
2013 Plan \| Subsequent Event
Stock Option and Compensation Plans
Increase in number of shares available under the Plan (in shares)	1,429,000
2013 Plan \| Maximum
Stock Option and Compensation Plans
Number of shares reserved for issuance under the Plan (in shares)						3,359,641

Stock Option and Compensation Plans - Summary of Stock Option Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Common Stock Options
Outstanding at beginning of year (in shares)	3,009	3,680	2,708
Granted (in shares)	972	764	1,744
Exercised (in shares)	(428)	(1,133)	(621)
Expired or forfeited (in shares)	(194)	(302)	(151)
Outstanding at end of year (in shares)	3,359	3,009	3,680
Weighted Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 30.43	$ 21.03	$ 9.41
Granted (in dollars per share)	60.40	47.31	33.92
Exercised (in dollars per share)	15.73	10.31	4.75
Expired or forfeited (in dollars per share)	48.63	34.09	28.50
Outstanding at end of year (in dollars per share)	$ 39.92	$ 30.43	$ 21.03
Options exercisable at end of year (in shares)	1,531	955	993
Weighted average grant date fair value (per share) of options granted during the period (in dollars per share)	$ 38.18	$ 31.33	$ 24.41

Stock Option and Compensation Plans - Options Outstanding and Exercisable by Exercise Price and Options Exercised (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Options Outstanding
Total Options Outstanding (in shares) \| shares	3,359
Weighted Average Remaining Life (Years)	7 years 7 months 6 days
Weighted Average Exercise Price (in dollars per share)	$ 39.92
Aggregate Intrinsic Value of Options Outstanding \| $	$ 254
Options Exercisable
Number Exercisable (in shares) \| shares	1,531
Weighted Average Exercise Price (in dollars per share)	$ 31.19
Aggregate Intrinsic Value of Options Exercisable \| $	$ 254
$0.12-$10.03
Options Outstanding
Total Options Outstanding (in shares) \| shares	193
Weighted Average Remaining Life (Years)	5 years 3 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 6.84
Options Exercisable
Number Exercisable (in shares) \| shares	137
Weighted Average Exercise Price (in dollars per share)	$ 5.52
Exercise prices, low end of range (in dollars per share)	0.12
Exercise prices, high end of range (in dollars per share)	$ 10.03
$10.04-$20.00
Options Outstanding
Total Options Outstanding (in shares) \| shares	273
Weighted Average Remaining Life (Years)	6 years 6 months
Weighted Average Exercise Price (in dollars per share)	$ 13.44
Options Exercisable
Number Exercisable (in shares) \| shares	170
Weighted Average Exercise Price (in dollars per share)	$ 13.48
Exercise prices, low end of range (in dollars per share)	10.04
Exercise prices, high end of range (in dollars per share)	$ 20.00
$20.01-$30.00
Options Outstanding
Total Options Outstanding (in shares) \| shares	154
Weighted Average Remaining Life (Years)	6 years 9 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 25.56
Options Exercisable
Number Exercisable (in shares) \| shares	114
Weighted Average Exercise Price (in dollars per share)	$ 25.53
Exercise prices, low end of range (in dollars per share)	20.01
Exercise prices, high end of range (in dollars per share)	$ 30.00
$30.01-$40.00
Options Outstanding
Total Options Outstanding (in shares) \| shares	1,087
Weighted Average Remaining Life (Years)	6 years 8 months 12 days
Weighted Average Exercise Price (in dollars per share)	$ 32.70
Options Exercisable
Number Exercisable (in shares) \| shares	758
Weighted Average Exercise Price (in dollars per share)	$ 32.97
Exercise prices, low end of range (in dollars per share)	30.01
Exercise prices, high end of range (in dollars per share)	$ 40.00
$40.01-$55.00
Options Outstanding
Total Options Outstanding (in shares) \| shares	1,125
Weighted Average Remaining Life (Years)	8 years 7 months 6 days
Weighted Average Exercise Price (in dollars per share)	$ 46.22
Options Exercisable
Number Exercisable (in shares) \| shares	319
Weighted Average Exercise Price (in dollars per share)	$ 45.49
Exercise prices, low end of range (in dollars per share)	40.01
Exercise prices, high end of range (in dollars per share)	$ 55.00
$55.01-$73.22
Options Outstanding
Total Options Outstanding (in shares) \| shares	527
Weighted Average Remaining Life (Years)	9 years
Weighted Average Exercise Price (in dollars per share)	$ 71.33
Options Exercisable
Number Exercisable (in shares) \| shares	33
Weighted Average Exercise Price (in dollars per share)	$ 69.08
Exercise prices, low end of range (in dollars per share)	55.01
Exercise prices, high end of range (in dollars per share)	$ 73.22

Stock Option and Compensation Plans Stock Option and Compensation Plans - Schedule of Cash Proceeds From and Aggregate Intrinsic Value of Stock Options Exercised (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Cash proceeds from options exercised	$ 6,934	$ 11,473	$ 2,949
Aggregate intrinsic value of options exercised	$ 14,439	$ 49,255	$ 21,646

Stock Option and Compensation Plans - Summary of Outstanding RSU Awards Granted (Details) - Restricted stock units shares in Thousands	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Restricted Stock Units
Outstanding, beginning of period (in shares) \| shares	288
Awarded (in shares) \| shares	583
Vested (in shares) \| shares	(109)
Forfeited (in shares) \| shares	(41)
Outstanding, end of period (in shares) \| shares	721
Weighted Average Grant-Date Fair Value
Outstanding, beginning of period (in dollars per share) \| $ / shares	$ 44.54
Awarded (in dollars per share) \| $ / shares	58.19
Vested (in dollars per share) \| $ / shares	43.88
Forfeited (in dollars per share) \| $ / shares	50.60
Outstanding, end of period (in dollars per share) \| $ / shares	$ 55.33

Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
Employee Benefit Plan (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Defined contribution plan, cost recognized	$ 0.8	$ 0.5	$ 0.2

Fair Value Measurements (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Fair Value Measurements
Investments in U.S. Treasury securities and Corporate debt securities	$ 155,348,000	$ 170,029,000
Transfer of assets from Level 1 to Level 2 of the fair value measurement hierarchy	0	0
Transfer of assets from Level 2 to Level 1 of the fair value measurement hierarchy	0	0
Recurring basis \| Quoted prices in active markets for identical assets (Level 1) \| Money market funds
Fair Value Measurements
Investments in money market funds and U.S. Treasury securities with maturities less than 90 days	108,096,000	196,188,000
Recurring basis \| Quoted prices in active markets for identical assets (Level 1) \| U.S. Treasury securities
Fair Value Measurements
Investments in money market funds and U.S. Treasury securities with maturities less than 90 days		150,387,000
Investments in U.S. Treasury securities and Corporate debt securities	120,261,000
Recurring basis \| Quoted prices in active markets for identical assets (Level 1) \| Corporate debt securities
Fair Value Measurements
Investments in U.S. Treasury securities and Corporate debt securities	0	0
Recurring basis \| Significant other observable inputs (Level 2) \| Money market funds
Fair Value Measurements
Investments in money market funds and U.S. Treasury securities with maturities less than 90 days	0	0
Recurring basis \| Significant other observable inputs (Level 2) \| U.S. Treasury securities
Fair Value Measurements
Investments in money market funds and U.S. Treasury securities with maturities less than 90 days		0
Investments in U.S. Treasury securities and Corporate debt securities	0
Recurring basis \| Significant other observable inputs (Level 2) \| Corporate debt securities
Fair Value Measurements
Investments in U.S. Treasury securities and Corporate debt securities	35,087,000	39,833,000
Recurring basis \| Significant unobservable inputs (Level 3) \| Money market funds
Fair Value Measurements
Investments in money market funds and U.S. Treasury securities with maturities less than 90 days	0	0
Recurring basis \| Significant unobservable inputs (Level 3) \| U.S. Treasury securities
Fair Value Measurements
Investments in money market funds and U.S. Treasury securities with maturities less than 90 days		0
Investments in U.S. Treasury securities and Corporate debt securities	0
Recurring basis \| Significant unobservable inputs (Level 3) \| Corporate debt securities
Fair Value Measurements
Investments in U.S. Treasury securities and Corporate debt securities	$ 0	$ 0

Selected Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Collaboration revenue	$ 5,322	$ 1,668	$ 28,198	$ 15,721	$ 4,782	$ 3,448	$ 1,597	$ 41,678	$ 50,909	$ 51,505	$ 41,259
Research and development expenses	59,409	50,854	48,262	37,770	33,917	40,479	32,059	24,557	196,295	131,012	88,385
General and administrative expenses	12,968	12,024	10,489	14,696	12,066	10,412	11,959	9,584	50,178	44,021	33,387
Loss from operations	(67,055)	(61,210)	(30,553)	(36,745)	(41,201)	(47,443)	(42,421)	7,537	$ (195,564)	$ (123,528)	$ (80,513)
Net income (loss) attributable to common stockholders	$ (66,283)	$ (60,891)	$ (29,945)	$ (36,301)	$ (35,649)	$ (39,573)	$ (37,131)	$ 6,636
Basic and diluted (in dollars per share)	$ (1.86)	$ (1.71)	$ (0.85)	$ (1.03)					$ (5.45)	$ (3.06)	$ (3.51)
Basic earnings (loss) per common share (in dollars per share)					$ (1.02)	$ (1.14)	$ (1.08)	$ 0.19
Diluted earnings (loss) per common share (in dollars per share)					$ (1.02)	$ (1.14)	$ (1.08)	$ 0.19

Subsequent Events (Details) - Subsequent Event - Scenario, Forecast - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Sep. 30, 2017	Jun. 30, 2017
Subsequent Event [Line Items]
Expected costs		$ 14.4
Costs expected to result in future cash expenditures		$ 13.8
Minimum
Subsequent Event [Line Items]
Estimated annualized cost savings from reduction in personnel	$ 25.0
Maximum
Subsequent Event [Line Items]
Estimated annualized cost savings from reduction in personnel	$ 30.0
Reduction in Personnel
Subsequent Event [Line Items]
Percent of personnel expected to be effected by reduction in workforce		80.00%
Expected costs		$ 12.3
Lease Termination
Subsequent Event [Line Items]
Expected costs		$ 2.1