IVERIC bio (ISEE) 10-K 5 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 27, 2018	Jun. 30, 2017
Document And Entity Information
Entity Registrant Name	Ophthotech Corp.
Entity Central Index Key	1,410,939
Document Type	10-K
Document Period End Date	Dec. 31, 2017
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	Accelerated Filer
Entity Public Float			$ 91.8
Entity Common Stock, Shares Outstanding		36,151,332
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 166,972	$ 133,930
Available for sale securities	0	155,348
Due from Novartis Pharma AG	0	3,531
Prepaid expenses and other current assets	3,146	3,078
Income tax receivable	1,387	0
Total current assets	171,505	295,887
Property and equipment, net	518	3,281
Deferred tax assets	3,529	0
Other assets	24	462
Total assets	175,576	299,630
Current liabilities
Accrued research and development expenses	4,984	47,240
Accounts payable and accrued expenses	7,551	12,032
Deferred revenue	0	6,646
Total current liabilities	12,535	65,918
Deferred revenue, long-term	0	203,330
Royalty purchase liability	125,000	125,000
Total liabilities	137,535	394,248
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, 36,110,298 and 35,733,276 shares issued and outstanding at December 31, 2017 and December 31, 2016, respectively	36	36
Additional paid-in capital	522,759	504,517
Accumulated deficit	(484,754)	(598,959)
Accumulated other comprehensive loss	0	(212)
Total stockholders' equity (deficit)	38,041	(94,618)
Total liabilities and stockholders' equity (deficit)	$ 175,576	$ 299,630

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
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)	36,110,298	35,733,276
Common stock, shares outstanding (in shares)	36,110,298	35,733,276

Statements of Operations

Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Collaboration revenue	$ 209,977	$ 50,909	$ 51,505
Operating expenses:
Research and development	66,289	196,295	131,012
General and administrative	35,683	50,178	44,021
Total operating expenses	101,972	246,473	175,033
Income (loss) from operations	108,005	(195,564)	(123,528)
Interest income	1,522	1,704	971
Other income (expense)	(34)	34	53
Income (loss) before income tax benefit	109,493	(193,826)	(122,504)
Income tax benefit	(4,712)	(406)	(16,787)
Net income (loss)	$ 114,205	$ (193,420)	$ (105,717)
Net income (loss) per common share:
Basic (in dollars per share)	$ 3.18	$ (5.45)	$ (3.06)
Dilutive (in dollars per share)	$ 3.17	$ (5.45)	$ (3.06)
Weighted average common shares outstanding:
Basic (in shares)	35,919	35,486	34,580
Dilutive (in shares)	36,007	35,486	34,580

Statements of Comprehensive Inc

Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ 114,205	$ (193,420)	$ (105,717)
Other comprehensive income (loss):
Unrealized gain (loss) on available for sale securities, net of tax	212	261	(408)
Other comprehensive income (loss)	212	261	(408)
Comprehensive income (loss)	$ 114,417	$ (193,159)	$ (106,125)

Statements of Stockholders' Equ

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, 2014	$ 128,537	$ 0	$ 34	$ 428,390	$ (299,822)	$ (65)
Balance at beginning 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
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
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants	71		$ 0	71
Issuance of common stock under employee stock compensation plans and warrants (in shares)			377
Share-based compensation	18,171			18,171
Net loss	114,205				114,205
Unrealized gain (loss) on available for sale securities, net of tax	212					212
Ending balance at Dec. 31, 2017	$ 38,041	$ 0	$ 36	$ 522,759	$ (484,754)	$ 0
Balance at end of period (in shares) at Dec. 31, 2017		0	36,110

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities
Net income (loss)	$ 114,205	$ (193,420)	$ (105,717)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Depreciation	2,763	757	698
Amortization of premium and discounts on investment securities	140	595	2,846
Gain on sale of marketable securities	0	0	(57)
Deferred income taxes	(3,366)	22,954	(17,341)
Share-based compensation	18,171	31,660	24,760
Excess tax benefits from share-based compensation	0	0	(1,302)
Changes in operating assets and liabilities:
Income tax receivable	(1,387)	3,421	48
Due from Novartis Pharma AG	3,531	858	(3,429)
Prepaid expense and other current assets	(68)	(995)	3,260
Accrued interest receivable	466	203	155
Other assets	438	27	(107)
Accrued research and development expenses	(42,256)	28,420	10,902
Accounts payable and accrued expenses	(4,481)	14	3,311
Deferred revenue	(209,977)	(3,090)	3,442
Net cash used in operating activities	(121,821)	(108,596)	(78,531)
Investing Activities
Purchase of marketable securities	(12,014)	(72,197)	(411,565)
Sale of marketable securities	0	0	395,977
Maturities of marketable securities	166,806	86,500	266,000
Purchase of property and equipment	0	(572)	(2,615)
Proceeds from sale of assets	0	0	6
Net cash provided by investing activities	154,792	13,731	247,803
Financing Activities
Proceeds from stock option/warrant exercises	71	6,934	11,473
Excess tax benefits from share-based compensation	0	0	1,302
Net cash provided by financing activities	71	6,934	12,775
Net change in cash and cash equivalents	33,042	(87,931)	182,047
Cash and cash equivalents
Beginning of period	133,930	221,861	39,814
End of period	166,972	133,930	221,861
Supplemental disclosure of cash paid
Income taxes paid (received), net	(245)	(26,998)	399
Supplemental disclosures of non-cash information related to investing activities
Change in unrealized gain (loss) on available for sale securities, net of tax	$ 212	$ 261	$ (408)

Business

Business	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	Business Description of Business and Organization Ophthotech Corporation (the “Company” or “Ophthotech”) was incorporated on January 5, 2007, in Delaware. The Company is a science-driven biopharmaceutical company specializing in the development of novel therapies to treat ophthalmic diseases, with a focus on age-related and orphan retinal diseases. The Company's multi-track strategy is to leverage its clinical experience and retina expertise to develop therapies for large market, age-related retinal diseases, where unmet medical needs remain for these patients, and for orphan eye diseases with a focus on underserved patients, and to utilize a disciplined business development approach to obtain additional products, product candidates and technologies in these disease areas. The Company is developing Zimura® (avacincaptad pegol), its complement C5 inhibitor, for dry and wet forms of 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 loss of central vision, and autosomal recessive Stargardt disease, or STDG1, which is an orphan inherited retinal disease that also may result in loss of central and peripheral vision. The Company is actively engaged in extensive business development efforts to identify, evaluate and potentially obtain rights to and develop additional therapeutic and gene therapy product candidates that would complement its strategic goals and leverage its competitive advantages. The Company believes that its strategy will provide multiple potential opportunities to bring ophthalmic therapies to market.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	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, 2017, the Company had cash and cash equivalents of approximately $167.0 million . The Company believes that its existing cash and cash equivalents as of December 31, 2017 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 In May 2014, the Company received an upfront payment of $200.0 million in connection with its licensing and commercialization agreement (the “Novartis Agreement”) with Novartis Pharma AG ("Novartis"). Prior to the third quarter of 2017, this payment had not been recorded as revenue due to the existence of a contingency with respect to the Company's right to terminate the agreement in certain circumstances and the associated termination fee equivalent to the entire $200.0 million upfront payment, which the Company would have been required to pay if it had elected to exercise this termination option. The Company and Novartis entered into a letter agreement in July 2017 (the "Letter Agreement") that waived the Company's termination right, thereby resolving the contingency and allowing the Company to immediately recognize as revenue the portion of the upfront payment allocated using the relative selling price method to deliverables completed during prior periods. See "Note 5-Licensing and Commercialization Agreement with Novartis Pharma AG" below for a further description of the Letter Agreement. During the third quarter of 2017, the Company completed the remaining deliverables under the Novartis Agreement and the Letter Agreement and recognized as revenue the balance of all of the payments previously received from Novartis related to licensing, research and development, manufacturing and joint operating committee activities that had been previously deferred using the relative selling price method. In total, during the third quarter of 2017, the Company recognized $206.7 million in previously deferred collaboration revenue in connection with the Novartis Agreement. The recognition of this revenue during the period did not impact the Company's cash balance. On October 23, 2017, following the failure of the Phase 3 Fovista program and pursuant to the terms of the Letter Agreement, Novartis elected to terminate the Novartis Agreement with immediate effect. Below is a summary of the components of the Company's collaboration revenue for the years ended December 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 License revenue $ 152,912 $ 22,937 $ 38,083 Research and development activity revenue 56,180 9,741 8,378 API transfer revenue 754 18,212 5,020 Joint operating committee revenue 131 19 24 Total collaboration revenue $ 209,977 $ 50,909 $ 51,505 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 Zimura on a purchase order basis. The Company also engages a single third-party manufacturer to provide fill/finish services for clinical supplies of Zimura. In addition, the Company currently relies upon a single third-party supplier to supply it with the proprietary polyethylene glycol, or PEG, reagent used to manufacture Zimura 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 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. Amortization of leasehold improvements is recorded over the shorter of the lease term or estimated useful life of the related asset. Research and Development Research and development expenses primarily consist of costs associated with the manufacturing, development and clinical testing of Zimura and, historically, Fovista, 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. The Company expects that research and development expenses in the future will also include the costs of the Company's collaborative gene therapy research programs. 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. 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, 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 Expected common stock price volatility 81% 71% 72% Risk-free interest rate 1.82% - 2.38% 1.14% - 2.37% 1.35% - 2.24% Expected term of options (years) 6.1 6.1 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, 2017 2016 2015 Research and development $ 11,114 $ 21,380 $ 16,608 General and administrative 7,057 10,280 8,152 Total $ 18,171 $ 31,660 $ 24,760 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. Due to the recent development and termination of the Company's collaboration contracts with Novartis, the Company will not be impacted upon adoption of this standard. 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. Publicly-traded 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 publicly-traded business entities and all nonpublicly-traded 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 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. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business , in an effort to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The amendments of this ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. This new guidance will be applicable for the Company’s acquisitions on or after January 1, 2018.

Net Income (Loss) Per Common Sh

Net Income (Loss) Per Common Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Income (Loss) Per Common Share	Net Income (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, 2017 2016 2015 Basic and diluted net income (loss) per common share calculation: Net loss $ 114,205 $ (193,420 ) $ (105,717 ) Weighted average common shares outstanding - basic 35,919 35,486 34,580 Plus: net effect of dilutive stock options and unvested restricted stock units 88 — — Weighted average common shares outstanding - dilutive 36,007 35,486 34,580 Net income (loss) per common share - basic $ 3.18 $ (5.45 ) $ (3.06 ) Net income (loss) per common share - diluted $ 3.17 $ (5.45 ) $ (3.06 ) 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, 2017 2016 2015 Stock options outstanding 5,179 3,359 3,009 Restricted stock units 182 721 288 Total 5,361 4,080 3,297

Cash, Cash Equivalents and Avai

Cash, Cash Equivalents and Available for Sale Securities	12 Months Ended
	Dec. 31, 2017
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash, Cash Equivalents and Available for Sale Securities	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 $9.5 million and $25.8 million at December 31, 2017 and 2016 , respectively. Cash and cash equivalents at December 31, 2017 and December 31, 2016 also included $157.4 million and $108.1 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 no available for sale securities at December 31, 2017. At December 31, 2016, the Company held available for sale securities with a fair value totaling $155.3 million . These available for sale securities consisted of U.S. Treasury securities and investment-grade corporate debt securities. During the year ended December 31, 2017 , the Company's investments matured and were reinvested in money market funds. 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 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, 2017 and December 31, 2016 were as follows: Years ended December 31, 2017 2016 Beginning balance $ (212 ) $ (473 ) Current period changes in fair value before reclassifications, net of tax 212 261 Amounts reclassified from accumulated other comprehensive income (loss), net of tax — — Total other comprehensive income (loss) 212 261 Ending balance $ — $ (212 )

Licensing and Commercialization

Licensing and Commercialization Agreement with Novartis Pharma AG	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Licensing and Commercialization Agreement with Novartis Pharma AG	Licensing and Commercialization Agreement with Novartis Pharma AG In May 2014, the Company entered into 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 API supplied by the Company, standalone Fovista products and products combining Fovista with an anti-VEGF agent 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 agreed to use commercially reasonable efforts to complete its ongoing pivotal Phase 3 clinical program for Fovista and Novartis agreed to use commercially reasonable efforts to develop a standalone Fovista product and a co-formulated product containing Fovista and an anti-VEGF agent 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. In July 2017, the Company and Novartis entered into the Letter Agreement to streamline the process and timeline for evaluating data from the OPH1004 trial once it became available. On October 23, 2017, following the failure of the Phase 3 Fovista program and pursuant to the terms of the Letter Agreement, Novartis elected to terminate the Novartis Agreement with immediate effect. In May 2014, Novartis paid the Company a $200.0 million upfront 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 in enrollment-based milestones under the Novartis Agreement. The Company used the relative selling price method to allocate these payments to contract deliverables based on its performance obligations 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 included 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 2 trials 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”). The Company’s obligation to provide access to clinical and regulatory information as part of the License Deliverable included the obligation to provide access to all clinical data, regulatory filings, safety data and manufacturing data to Novartis which was necessary for the commercialization of Fovista in the Novartis Territory. The R&D Activity Deliverable included the right and responsibility for the Company to conduct the Phase 3 Fovista clinical program and other Phase 2 studies of Fovista which were necessary or desirable for regulatory approval or commercialization of Fovista. The Manufacturing Deliverable included the obligation for the Company to supply API to Novartis for clinical purposes, for which Novartis agreed to pay the Company’s manufacturing costs. The Joint Operating Committee Deliverable included 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 was accounted for separately. The Novartis Agreement included a termination right for the Company in the event that specified governmental actions prevented the parties from materially progressing the development or commercialization of licensed products. If the Company elected to exercise this termination option, it would have been required to pay a substantial termination fee equivalent to the entire upfront payment amount. The Company concluded that this termination provision constituted a contingent event that was unknown at the inception of the agreement. As such, the Company recorded the $200.0 million upfront payment in deferred revenue, long-term until such time that the contingency related to this termination provision was resolved. In July 2017, the contingency was resolved when the Company permanently waived this termination right as part of the Letter Agreement. The Letter Agreement also provided Novartis with a shorter notice period in the event Novartis determined to terminate the Novartis Agreement in certain circumstances. In addition, the Letter Agreement provided Novartis with a fully paid-up, royalty free license to use data from the Lucentis monotherapy arms of the Company's Phase 2b OPH1001 trial and Phase 3 OPH1002 and OPH1003 trials in the Novartis Territory in connection with the development, manufacturing and commercialization of Novartis-controlled anti-VEGF products. The Lucentis study data license continues until the fifth anniversary of the Letter Agreement. The Company evaluated the Letter Agreement under ASC 605-25 and determined that the Letter Agreement does not create any new deliverables. The Company is treating the Fovista license granted at the inception of the Novartis Agreement and the Lucentis study data license granted under the Letter Agreement as one collective technology license (the "Licenses") delivered at the inception of the Novartis Agreement. In addition, as the waiver of its right to terminate the Novartis Agreement as a result of specified governmental actions resolved the Company’s contingency with respect to such termination right and the associated termination fee, the Company allocated the entire previously deferred amount, $200.0 million , to the deliverables that were determined based on the relative selling price at contract inception. Upon entry into the Letter Agreement in July 2017, the Company immediately recognized as revenue $189.8 million of the upfront payment allocated to contract deliverables completed during prior periods. Upon termination of the OPH1004 trial in August 2017, the Company recognized the remaining $16.9 million of collaboration revenue, attributable to the R&D Deliverable, previously deferred under the Novartis Agreement. In total, during the third quarter of 2017, the Company recognized $206.7 million in previously deferred collaboration revenue in connection with the Novartis Agreement. The recognition of this revenue during the period did not impact the Company's cash balance. Below is a summary of the components of the Company's collaboration revenue for the years ended December 31, 2017 , 2016 , and 2015 : Years ended December 31, 2017 2016 2015 License revenue $ 152,912 $ 22,937 $ 38,083 Research and development activity revenue 56,180 9,741 8,378 API transfer revenue 754 18,212 5,020 Joint operating committee revenue 131 19 24 Total collaboration revenue $ 209,977 $ 50,909 $ 51,505

Financing Agreement with Novo A

Financing Agreement with Novo A/S	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Financing Agreement with Novo A/S	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. The Company's obligations under the Novo agreement are secured by a lien on certain of the Company's intellectual property and other rights related to Fovista and other anti-PDGF products the Company may develop. 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, 2017, 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

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment as of December 31, 2017 and 2016 were as follows: Useful Life (Years) December 31, December 31, Manufacturing and clinical equipment 7 - 10 $ 412 $ 617 Computer, software and other office equipment 5 933 1,711 Furniture and fixtures 7 — 774 Leasehold improvements 3 - 5 — 1,835 1,345 4,937 Accumulated depreciation (827 ) (1,656 ) Property and equipment, net $ 518 $ 3,281 For the years ended December 31, 2017 , 2016 and 2015 , depreciation expense was $2.8 million , $0.8 million and $0.7 million , respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the U.S. Tax Cuts and Jobs Act (“TCJA”) was enacted reducing the corporate tax rate from 35% to 21% effective for tax years beginning on or after January 1, 2018. ASC 740, Income Taxes requires the effects of changes in tax laws to be recognized in the period in which the legislation is enacted. However, due to the complexity and significance of the Tax Act’s provisions, the SEC staff issued SAB 118, which allows companies to record the tax effects of the TCJA on a provisional basis based on a reasonable estimate, and then, if necessary, subsequently adjust such amounts during a limited measurement period as more information becomes available. The measurement period ends when a company has obtained, prepared, and analyzed the information necessary to finalize its accounting, but cannot extend beyond one year from enactment. Under the TCJA, the Corporate Alternative Minimum Tax ("AMT") was repealed. The Company's previously recorded Alternative Minimum Tax (“AMT”) credits of approximately $3.5 million are now refundable over a four year period beginning in 2018 and the previously recorded valuation allowance for these AMT credits was reversed during the year ended December 31, 2017. As a result of the reduction in the corporate tax rate from 35% to 21% the value of the Company’s deferred tax assets, and related valuation allowance, were reduced by a provisional amount of approximately $54.6 million . The Company does not have any offshore earnings from which to record the mandatory transition tax. Given the significant complexity of the TCJA, anticipated guidance from the US Treasury about implementing the TCJA, and the potential for additional guidance from the SEC or the FASB related to the TCJA, the deferred taxes provisional amounts may be adjusted during the measurement period. These provisional amounts were based on the Company’s present interpretations of the TCJA and current available information, including assumptions and expectations about future events, such as its projected financial performance, and are subject to further refinement as additional information becomes available (including potential new or interpretative guidance issued by the FASB or the Internal Revenue Service and other tax agencies) and further analyses are completed. 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, 2017 2016 2015 Percent of pre-tax income: U.S. federal statutory income tax rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit 14.6 % 2.8 % 7.4 % Permanent items 4.0 % (1.4 )% (0.5 )% Remeasurement of deferred tax assets 49.9 % — % — % Impact of state rate changes (27.9 )% (11.0 )% 0.9 % Research and development credit — % 1.9 % — % Alternative minimum tax credit (1.3 )% 1.1 % — % Change in valuation allowance (78.6 )% (28.2 )% (29.1 )% Effective income tax rate (4.3 )% 0.2 % 13.7 % The components of income tax (benefit) expense are as follows: Years ended December 31, 2017 2016 2015 Current: Federal $ 173 $ (23,393 ) $ 136 State (1,356 ) 21 91 Deferred: Federal (3,529 ) 22,966 (17,014 ) State — — — Income tax benefit $ (4,712 ) $ (406 ) $ (16,787 ) Significant components of the Company's deferred tax assets (liabilities) for 2017 and 2016 consist of the following: As of December 31, 2017 2016 Deferred tax assets (liabilities) Deferred revenue $ 40,961 $ 125,634 License and technology payments 8,222 10,532 Share-based compensation 17,599 16,494 Accrued expenses 608 530 Depreciation 81 (651 ) Federal and state net operating loss carryforwards 76,309 75,177 Research and development credits 3,782 3,720 Other 3,534 2,155 Deferred income tax assets 151,096 233,591 Valuation allowance (147,567 ) (233,591 ) Net deferred tax assets $ 3,529 $ — 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. The Company incurred tax losses in 2017 and 2016. The Company realized its net deferred tax assets recorded as of December 31, 2016 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, 2017, the Company has federal NOL carryforwards of approximately $270.0 million . These losses are due to expire in 2036 and 2037. For the year ended December 31, 2017 , the Company recorded an income tax benefit of $4.7 million which primarily related to a $ 3.5 million reduction in our valuation allowances for AMT credits to reflect the impact of the TCJA enactment and a settlement of a state franchise tax audit for $1.4 million partially offset by the reversal of previously recoded benefits related to the change in unrealized gains of the Company's investment portfolio. Although the Company generated $109.5 million of net income before income taxes for the year ended December 31, 2017 as a result of the recognition of deferred revenue under the Novartis Agreement, the Company expects a net loss for tax purposes for 2017 with minimal taxes due. For tax purposes, the Company treated payments received under the Novartis Agreement as revenue at the time the payments were received. The benefit from income taxes of $0.4 million recorded in 2016 was related to unanticipated refunds received and the reduction in the Company's valuation allowances to reflect the income tax associated with unrealized gains in the Company's investment portfolio. In the second quarter of 2017, the IRS concluded an audit of the Company’s U.S. federal income tax returns for the years 2013, 2014 and 2015, resulting in an immaterial amount of additional tax due. Federal net operating losses for 2016 and general business credits generated between 2007 and 2016 remain subject to audit. 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, 2017 , the Company reduced certain deferred tax assets by $6.2 million and reduced the corresponding valuation allowance by an equivalent amount. Additionally, the Company amended certain state income tax returns to claim a refund for taxes previously paid. These claims may result in refunds to the Company of up to approximately $6.5 million . 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 $ 4,128 Gross amount of increases in unrecognized tax benefits during the period - current year provisions 343 Gross amount of increases in unrecognized tax benefits during the period - prior year provisions 14,430 Gross amount of increases in unrecognized tax benefits during the period - other — Decreases due to settlement with tax authorities during the period (2,020 ) Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period — Closing Balance $ 16,881 As the Company is currently being audited by the New York City Department of Finance and the New Jersey Division of Taxation, an estimate of unrecognized tax benefits that may be realized over the next twelve months is expected to be in the range of zero to approximately $6.9 million . 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

Operating Leases	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Operating Leases	Operating Leases The Company leases office space located in New York, New York and Princeton, New Jersey under operating lease arrangements. The lease for the Company's New York office space expires at the end of 2018, whereas the lease for the Company's Princeton office space expires in March 2020. Future minimum rental commitments under non-cancelable operating leases in effect as of December 31, 2017 , are as follows: 2018 $ 895 2019 48 2020 8 Total $ 951 Rent expense is calculated on the straight-line basis and amounted to $3.6 million , $3.0 million and $2.1 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. In January 2017, the Company terminated its office leases in New York, New York and Princeton, New Jersey and made aggregate termination payments of approximately $2.1 million .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Under various agreements, the Company may be required to pay royalties and make milestone payments. These agreements include the following: • Under a license agreement with Archemix Corp., or Archemix, for each anti‑C5 aptamer product that the Company may develop under the agreement, including Zimura, the Company is obligated to make additional payments to Archemix of up to an aggregate of $57.5 million if the Company achieves specified development, clinical and regulatory milestones, with $30.5 million of such payments relating a first indication, $24.5 million of such payments relating to second and third indications and $2.5 million of such payments relating to sustained delivery applications. Under the C5 agreement, the Company is also obligated to make additional payments to Archemix of up to an aggregate of $22.5 million if the Company achieves specified commercial milestones based on net product sales of all anti‑C5 products licensed under the agreement. 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 its rights under the C5 agreement. The Company is not obligated to pay Archemix a running royalty based on net product sales in connection with the C5 agreement. 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. 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 On January 11, 2017, a putative class action lawsuit was 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 v. Ophthotech Corporation, et al., No. 1:17-cv-00210. 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 agents for the treatment of wet AMD. The complaint seeks equitable and/or injunctive relief, unspecified damages, attorneys’ fees, and other costs. On March 9, 2017, a second putative class action lawsuit was filed against the Company and the same group of its current and former executive officers in the United States District Court for the Southern District of New York, captioned Wasson v. Ophthotech Corporation, et al., No. 1:17-cv-01758. The complaint purports to be brought on behalf of shareholders who purchased the Company’s common stock between May 11, 2015 and December 9, 2016. The allegations made in the complaint are similar to those made in the Micholle complaint. Putative lead plaintiffs in the Micholle action have moved to consolidate the Micholle and Wasson actions. On February 7, 2018, a shareholder derivative action was filed against the members of the Company’s Board of Directors in the New York Supreme Court Commercial Division, captioned Cano v. Guyer, et al., No. 650601/2018. The complaint alleges that defendants breached their fiduciary duties to the Company by adopting a compensation plan that overcompensates the non-employee members of the Board relative to boards of companies of comparable market capitalization and size. The complaint also alleges that defendants were unjustly enriched as a result of the alleged conduct. The complaint purports to seek unspecified damages on behalf of the Company, as well as an order directing the Company to reform and improve its corporate governance and internal procedures to comply with applicable laws, attorneys’ fees, and other costs. The Company denies any allegations of wrongdoing and intends to vigorously defend against these lawsuits. The Company is unable, however, to predict the outcome of these matters 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. On May 30, 2017, a shareholder derivative action was filed against the members of the Company’s Board of Directors in the United States District Court for the Southern District of New York, captioned Etelmendorf v. Bolte, et al., No. 1:17-cv-04042. The complaint alleged that defendants breached their fiduciary duties to the Company by causing or permitting the Company to make allegedly false and/or misleading statements concerning the prospects of the Company’s Phase 3 trials for Fovista in combination with anti-VEGF agents for the treatment of wet AMD, and by approving certain executive compensation. The complaint also alleged that defendants were unjustly enriched as a result of the alleged conduct. The complaint purported to seek unspecified damages on behalf of the Company, as well as an order directing the Company to reform and comply with its governance obligations, attorneys’ fees, and other costs. The defendants moved to dismiss the action in its entirety. Rather than oppose the motion to dismiss, on October 17, 2017, the plaintiff filed a notice of voluntary dismissal without prejudice for this action.

Stock Option and Compensation P

Stock Option and Compensation Plans	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option and Compensation Plans	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. Annual increases under the evergreen provisions of the 2013 Plan have resulted in the addition of an aggregate of approximately 6,898,000 additional shares to the 2013 Plan, including for 2018, an increase of approximately 1,444,000 shares, or 4% of the total number of shares of the Company's common stock outstanding as of January 1, 2018. As of December 31, 2017 , the Company had approximately 492,000 shares available for grant under the 2013 Plan. 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, 2017 , 2016 and 2015 is as follows (in thousands except weighted average exercise price): Years ended December 31, 2017 2016 2015 Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Outstanding, December 31, 2016 3,359 $ 39.92 3,009 $ 30.43 3,680 $ 21.03 Granted 3,024 $ 3.50 972 $ 60.40 764 $ 47.31 Exercised (20 ) $ 1.64 (428 ) $ 15.73 (1,133 ) $ 10.31 Expired or forfeited (1,079 ) $ 38.17 (194 ) $ 48.63 (302 ) $ 34.09 Outstanding, December 31, 2017 5,284 $ 19.58 3,359 $ 39.92 3,009 $ 30.43 Years ended December 31, 2017 2016 2015 Options exercisable at December 31, 2017 1,954 1,531 955 Weighted average grant date fair value (per share) of options granted during the period $ 2.45 $ 38.18 $ 31.33 As of December 31, 2017 , there were approximately 4,801,000 options outstanding, net of estimated forfeitures, that had vested or are expected to vest. The weighted-average exercise price of these options was $20.47 per option; the weighted-average remaining contractual life of these options was 8.1 years; and the aggregate intrinsic value of these options was approximately $0.4 million . A summary of the stock options outstanding and exercisable as of December 31, 2017 is as follows (in thousands except exercise prices and weighted average exercise price): December 31, 2017 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 3,054 9.3 $ 3.68 210 $ 6.62 $10.04-$20.00 204 5.5 $ 13.52 147 $ 13.63 $20.01-$30.00 127 5.9 $ 25.13 127 $ 25.13 $30.01-$40.00 831 5.5 $ 32.81 808 $ 32.82 $40.01-$55.00 708 7.5 $ 46.40 467 $ 46.13 $55.01-$73.22 360 8.0 $ 72.63 194 $ 72.13 5,284 8.2 $ 19.58 1,953 $ 35.15 Aggregate Intrinsic Value $ 492 $ 122 Cash proceeds from, and the aggregate intrinsic value of, stock options exercised during the years ended December 31, 2017 , 2016 and 2015 , respectively, were as follows: Years ended December 31, 2017 2016 2015 Cash proceeds from options exercised $ 33 $ 6,934 $ 11,473 Aggregate intrinsic value of options exercised $ 43 $ 14,439 $ 49,255 In connection with stock option awards granted to employees, the Company recognized approximately $13.1 million , $22.8 million and $15.5 million in share-based compensation expense during the years ended December 31, 2017 , 2016 and 2015 , respectively, net of expected forfeitures. As of December 31, 2017 , there were approximately $14.8 million of unrecognized compensation costs, net of estimated forfeitures, related to stock option awards granted to employees, which are expected to be recognized over a remaining weighted average period of 2.5 years. In connection with stock option awards granted to consultants, the Company recognized approximately $0.3 million , $1.7 million and $4.1 million in share-based compensation expense during the years ended December 31, 2017 , 2016 and 2015 , respectively, net of expected forfeitures. As of December 31, 2017 , there were approximately $0.2 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 1.8 years. The following table presents a summary of the Company's outstanding RSU awards granted as of December 31, 2017 (in thousands except weighted average grant-date fair value): Restricted Stock Units Weighted Average Grant-Date Fair Value Outstanding, December 31, 2016 721 $ 55.33 Awarded 249 $ 4.42 Vested (341 ) $ 20.15 Forfeited (302 ) $ 50.30 Outstanding, December 31, 2017 327 $ 51.08 As of December 31, 2017 , there were approximately 187,000 RSUs outstanding, net of estimated forfeitures, that are expected to vest. The weighted-average fair value of these RSUs was $47.25 per share; and the aggregate intrinsic value of these RSUs was approximately $0.6 million . In connection with RSUs granted to employees, the Company recognized approximately $4.4 million , $6.9 million and $5.2 million in share-based compensation expense during the years ended December 31, 2017 , 2016 and 2015 , respectively, net of expected forfeitures. As of December 31, 2017 , there was approximately $5.6 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 2.0 years. The total fair value of the RSUs that vested during the year ended December 31, 2017 was $7.5 million . In connection with RSUs granted to consultants, the Company recognized approximately $0.3 million in share-based compensation expense during the year ended December 31, 2017 , net of expected forfeitures. There were no RSUs granted to consultants during the year ended December 31, 2016 . As of December 31, 2017 , there were approximately $0.1 million of unrecognized compensation costs, net of estimated forfeitures, related to RSUs granted to consultants, which are expected to be recognized over a remaining weighted average period of 1.7 years. In connection with the ESPP made available to employees, the Company recognized a $0.1 million amount of share-based compensation expense during the years ended December 31, 2017 and December 31, 2016 , respectively, net of expected forfeitures. As of December 31, 2017 , there was a de minimis amount of unrecognized compensation costs, net of estimated forfeitures, related to the ESPP, which are expected to be recognized over 0.3 years. There were 16,358 shares of common stock issued under the ESPP during the year ended December 31, 2017 . Cash proceeds from ESPP purchases were $38 thousand during the year ended December 31, 2017 . There were no shares of common stock issued under the ESPP plan during the year ended December 31, 2016 , as the first offering period under the ESPP commenced in September 2016. As of December 31, 2017 , 983,642 shares were available for future purchases under the ESPP.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Employee Benefit Plan	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 $0.7 million , $0.8 million and $0.5 million during the years ended December 31, 2017 , 2016 and 2015 , respectively.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	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, 2017 : 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* $ 162,457 $ — $ — Investments in U.S. Treasury securities $ — $ — $ — Investments in Corporate debt securities $ — $ — $ — 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 $ — * 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, 2017 or December 31, 2016 .

Restructuring Activities

Restructuring Activities	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Restructuring Activities	Restructuring Activities In December 2016, the Company announced its intention 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 involving approximately 80% of the Company’s workforce based on the number of employees at the time the plan was approved. During the year ended December 31, 2017 , the Company's workforce has been reduced by 122 employees in connection with the reduction in personnel and through natural attrition. The Company substantially completed the reduction in personnel during 2017. In connection with such reduction in personnel, the Company incurred approximately $13.1 million of pre-tax charges through the fourth quarter of 2017, of which approximately $12.1 million in the aggregate is expected to result in cash expenditures. These pre-tax charges relate to (a) severance, stock compensation and other employee costs of approximately $11.0 million and (b) lease termination costs of approximately $2.1 million . As of December 31, 2017 , the Company's cash expenditures related to such reduction in personnel totaled $9.6 million . In connection with the reduction in personnel, the Company recognized approximately $11.0 million of severance, stock compensation and other employee costs for the year ended December 31, 2017 , of which $7.5 million was recorded in "Research and development" expense and $3.5 million were recorded in "General and administrative" expense in the Company's Statements of Operations. As of December 31, 2017 , the Company's accrual balance for severance and benefit costs was $2.5 million which was recorded in "Accounts payable and accrued expenses" in the Company's Balance Sheet. The severance and other employee cost accruals as of December 31, 2017 are expected to be paid through to December of 2018. The following is a reconciliation of the severance-related accrual activity for the year ended December 31, 2017 : Accrued Severance and Other Employee Costs Beginning Balance $ — Accrued restructuring expenses 12,105 Payments (9,576 ) Ending Balance $ 2,529 In January 2017, the Company issued a notice of termination under the Lease Agreement, dated as of September 30, 2007, between the Company and One Penn Plaza LLC, as previously supplemented and amended (as so supplemented and amended, the “Lease”) for office space at One Penn Plaza in New York, New York. The termination of the Lease triggered an early termination payment by the Company of approximately $0.9 million . On November 1, 2017, the Company and One Penn Plaza LLC executed a further amendment to the Lease. Payments under the further lease amendment will not constitute restructuring charges. On January 26, 2017, the Company issued a notice of termination under the Sublease Agreement between the Company and Otsuka America Pharmaceutical, Inc. (the “Sublease”) for office space at One University Square, Princeton, New Jersey. The termination of the Sublease triggered an early termination payment by the Company of approximately $1.2 million . On January 26, 2017, the Company issued a notice of termination under its Office Lease Agreement between the Company and PSN Partners, L.P. (the “Office Lease”) for office space in Palmer Square in Princeton, New Jersey. The termination of the Office Lease did not trigger any early termination payment. During January 2017, the Company made the early termination payments as described above and recognized $2.1 million of additional facilities costs which were recorded in "General and administrative" expense in the Company's Statements of Operations.

Selected Quarterly Financial In

Selected Quarterly Financial Information (unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Information (unaudited)	Selected Quarterly Financial Information (unaudited) The following is a summary of the quarterly results of operations for the years ended December 31, 2017 and 2016 : 2017 March 31 June 30 September 30 December 31 Collaboration revenue $ 1,662 $ 1,661 $ 206,654 $ — Research and development expenses 31,979 15,657 10,707 7,946 General and administrative expenses 13,159 8,552 7,059 6,913 Income (loss) from operations (43,476 ) (22,548 ) 188,888 (14,859 ) Net income (loss) attributable to common stockholders $ (43,122 ) $ (22,204 ) $ 189,073 $ (9,542 ) Basic earnings (loss) per common share $ (1.20 ) $ (0.62 ) $ 5.26 $ (0.26 ) Diluted earnings (loss) per common share $ (1.20 ) $ (0.62 ) $ 5.25 $ (0.26 ) 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 )

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	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	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	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	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.
Available for Sale Securities	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	Revenue Recognition Collaboration Revenue In May 2014, the Company received an upfront payment of $200.0 million in connection with its licensing and commercialization agreement (the “Novartis Agreement”) with Novartis Pharma AG ("Novartis"). Prior to the third quarter of 2017, this payment had not been recorded as revenue due to the existence of a contingency with respect to the Company's right to terminate the agreement in certain circumstances and the associated termination fee equivalent to the entire $200.0 million upfront payment, which the Company would have been required to pay if it had elected to exercise this termination option. The Company and Novartis entered into a letter agreement in July 2017 (the "Letter Agreement") that waived the Company's termination right, thereby resolving the contingency and allowing the Company to immediately recognize as revenue the portion of the upfront payment allocated using the relative selling price method to deliverables completed during prior periods. See "Note 5-Licensing and Commercialization Agreement with Novartis Pharma AG" below for a further description of the Letter Agreement. During the third quarter of 2017, the Company completed the remaining deliverables under the Novartis Agreement and the Letter Agreement and recognized as revenue the balance of all of the payments previously received from Novartis related to licensing, research and development, manufacturing and joint operating committee activities that had been previously deferred using the relative selling price method. In total, during the third quarter of 2017, the Company recognized $206.7 million in previously deferred collaboration revenue in connection with the Novartis Agreement. The recognition of this revenue during the period did not impact the Company's cash balance. On October 23, 2017, following the failure of the Phase 3 Fovista program and pursuant to the terms of the Letter Agreement, Novartis elected to terminate the Novartis Agreement with immediate effect. Below is a summary of the components of the Company's collaboration revenue for the years ended December 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 License revenue $ 152,912 $ 22,937 $ 38,083 Research and development activity revenue 56,180 9,741 8,378 API transfer revenue 754 18,212 5,020 Joint operating committee revenue 131 19 24 Total collaboration revenue $ 209,977 $ 50,909 $ 51,505
Concentration of Credit Risk	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	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 Zimura on a purchase order basis. The Company also engages a single third-party manufacturer to provide fill/finish services for clinical supplies of Zimura. In addition, the Company currently relies upon a single third-party supplier to supply it with the proprietary polyethylene glycol, or PEG, reagent used to manufacture Zimura 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 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	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	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 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. Amortization of leasehold improvements is recorded over the shorter of the lease term or estimated useful life of the related asset.
Research and Development	Research and Development Research and development expenses primarily consist of costs associated with the manufacturing, development and clinical testing of Zimura and, historically, Fovista, 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. The Company expects that research and development expenses in the future will also include the costs of the Company's collaborative gene therapy research programs. 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	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.
Share-Based Compensation	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, 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 Expected common stock price volatility 81% 71% 72% Risk-free interest rate 1.82% - 2.38% 1.14% - 2.37% 1.35% - 2.24% Expected term of options (years) 6.1 6.1 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, 2017 2016 2015 Research and development $ 11,114 $ 21,380 $ 16,608 General and administrative 7,057 10,280 8,152 Total $ 18,171 $ 31,660 $ 24,760
Recent Accounting Pronouncements	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. Due to the recent development and termination of the Company's collaboration contracts with Novartis, the Company will not be impacted upon adoption of this standard. 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. Publicly-traded 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 publicly-traded business entities and all nonpublicly-traded 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 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. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business , in an effort to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The amendments of this ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. This new guidance will be applicable for the Company’s acquisitions on or after January 1, 2018.

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
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 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 License revenue $ 152,912 $ 22,937 $ 38,083 Research and development activity revenue 56,180 9,741 8,378 API transfer revenue 754 18,212 5,020 Joint operating committee revenue 131 19 24 Total collaboration revenue $ 209,977 $ 50,909 $ 51,505
Schedule of weighted-average assumptions used to estimate grant date fair value of stock options	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, 2017 , 2016 and 2015 : Years ended December 31, 2017 2016 2015 Expected common stock price volatility 81% 71% 72% Risk-free interest rate 1.82% - 2.38% 1.14% - 2.37% 1.35% - 2.24% Expected term of options (years) 6.1 6.1 6.2 Expected dividend yield — — —
Schedule of share-based compensation expense	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, 2017 2016 2015 Research and development $ 11,114 $ 21,380 $ 16,608 General and administrative 7,057 10,280 8,152 Total $ 18,171 $ 31,660 $ 24,760

Net Loss Per Common Share (Tabl

Net Loss Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 2016 2015 Basic and diluted net income (loss) per common share calculation: Net loss $ 114,205 $ (193,420 ) $ (105,717 ) Weighted average common shares outstanding - basic 35,919 35,486 34,580 Plus: net effect of dilutive stock options and unvested restricted stock units 88 — — Weighted average common shares outstanding - dilutive 36,007 35,486 34,580 Net income (loss) per common share - basic $ 3.18 $ (5.45 ) $ (3.06 ) Net income (loss) per common share - diluted $ 3.17 $ (5.45 ) $ (3.06 )
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, 2017 2016 2015 Stock options outstanding 5,179 3,359 3,009 Restricted stock units 182 721 288 Total 5,361 4,080 3,297

Cash, Cash Equivalents and Av26

Cash, Cash Equivalents and Available for Sale Securities (Tables)	12 Months Ended
	Dec. 31, 2017
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
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, 2017 and December 31, 2016 were as follows: Years ended December 31, 2017 2016 Beginning balance $ (212 ) $ (473 ) Current period changes in fair value before reclassifications, net of tax 212 261 Amounts reclassified from accumulated other comprehensive income (loss), net of tax — — Total other comprehensive income (loss) 212 261 Ending balance $ — $ (212 )

Licensing and Commercializati27

Licensing and Commercialization Agreement with Novartis Pharma AG (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 , 2016 , and 2015 : Years ended December 31, 2017 2016 2015 License revenue $ 152,912 $ 22,937 $ 38,083 Research and development activity revenue 56,180 9,741 8,378 API transfer revenue 754 18,212 5,020 Joint operating committee revenue 131 19 24 Total collaboration revenue $ 209,977 $ 50,909 $ 51,505

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	Property and equipment as of December 31, 2017 and 2016 were as follows: Useful Life (Years) December 31, December 31, Manufacturing and clinical equipment 7 - 10 $ 412 $ 617 Computer, software and other office equipment 5 933 1,711 Furniture and fixtures 7 — 774 Leasehold improvements 3 - 5 — 1,835 1,345 4,937 Accumulated depreciation (827 ) (1,656 ) Property and equipment, net $ 518 $ 3,281

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 2016 2015 Percent of pre-tax income: U.S. federal statutory income tax rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit 14.6 % 2.8 % 7.4 % Permanent items 4.0 % (1.4 )% (0.5 )% Remeasurement of deferred tax assets 49.9 % — % — % Impact of state rate changes (27.9 )% (11.0 )% 0.9 % Research and development credit — % 1.9 % — % Alternative minimum tax credit (1.3 )% 1.1 % — % Change in valuation allowance (78.6 )% (28.2 )% (29.1 )% Effective income tax rate (4.3 )% 0.2 % 13.7 %
Schedule of components of income tax (benefit) expense	The components of income tax (benefit) expense are as follows: Years ended December 31, 2017 2016 2015 Current: Federal $ 173 $ (23,393 ) $ 136 State (1,356 ) 21 91 Deferred: Federal (3,529 ) 22,966 (17,014 ) State — — — Income tax benefit $ (4,712 ) $ (406 ) $ (16,787 )
Schedule of significant components of the Company's deferred tax assets (liabilities)	Significant components of the Company's deferred tax assets (liabilities) for 2017 and 2016 consist of the following: As of December 31, 2017 2016 Deferred tax assets (liabilities) Deferred revenue $ 40,961 $ 125,634 License and technology payments 8,222 10,532 Share-based compensation 17,599 16,494 Accrued expenses 608 530 Depreciation 81 (651 ) Federal and state net operating loss carryforwards 76,309 75,177 Research and development credits 3,782 3,720 Other 3,534 2,155 Deferred income tax assets 151,096 233,591 Valuation allowance (147,567 ) (233,591 ) Net deferred tax assets $ 3,529 $ —
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 $ 4,128 Gross amount of increases in unrecognized tax benefits during the period - current year provisions 343 Gross amount of increases in unrecognized tax benefits during the period - prior year provisions 14,430 Gross amount of increases in unrecognized tax benefits during the period - other — Decreases due to settlement with tax authorities during the period (2,020 ) Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period — Closing Balance $ 16,881

Operating Leases (Tables)

Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 , are as follows: 2018 $ 895 2019 48 2020 8 Total $ 951

Stock Option and Compensation31

Stock Option and Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 , 2016 and 2015 is as follows (in thousands except weighted average exercise price): Years ended December 31, 2017 2016 2015 Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Outstanding, December 31, 2016 3,359 $ 39.92 3,009 $ 30.43 3,680 $ 21.03 Granted 3,024 $ 3.50 972 $ 60.40 764 $ 47.31 Exercised (20 ) $ 1.64 (428 ) $ 15.73 (1,133 ) $ 10.31 Expired or forfeited (1,079 ) $ 38.17 (194 ) $ 48.63 (302 ) $ 34.09 Outstanding, December 31, 2017 5,284 $ 19.58 3,359 $ 39.92 3,009 $ 30.43 Years ended December 31, 2017 2016 2015 Options exercisable at December 31, 2017 1,954 1,531 955 Weighted average grant date fair value (per share) of options granted during the period $ 2.45 $ 38.18 $ 31.33
Summary of the stock options outstanding and exercisable	A summary of the stock options outstanding and exercisable as of December 31, 2017 is as follows (in thousands except exercise prices and weighted average exercise price): December 31, 2017 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 3,054 9.3 $ 3.68 210 $ 6.62 $10.04-$20.00 204 5.5 $ 13.52 147 $ 13.63 $20.01-$30.00 127 5.9 $ 25.13 127 $ 25.13 $30.01-$40.00 831 5.5 $ 32.81 808 $ 32.82 $40.01-$55.00 708 7.5 $ 46.40 467 $ 46.13 $55.01-$73.22 360 8.0 $ 72.63 194 $ 72.13 5,284 8.2 $ 19.58 1,953 $ 35.15 Aggregate Intrinsic Value $ 492 $ 122
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, 2017 , 2016 and 2015 , respectively, were as follows: Years ended December 31, 2017 2016 2015 Cash proceeds from options exercised $ 33 $ 6,934 $ 11,473 Aggregate intrinsic value of options exercised $ 43 $ 14,439 $ 49,255
Summary of the Company's outstanding shares of RSU awards	The following table presents a summary of the Company's outstanding RSU awards granted as of December 31, 2017 (in thousands except weighted average grant-date fair value): Restricted Stock Units Weighted Average Grant-Date Fair Value Outstanding, December 31, 2016 721 $ 55.33 Awarded 249 $ 4.42 Vested (341 ) $ 20.15 Forfeited (302 ) $ 50.30 Outstanding, December 31, 2017 327 $ 51.08

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of assets and liabilities that are measured at fair value on a recurring basis	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, 2017 : 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* $ 162,457 $ — $ — Investments in U.S. Treasury securities $ — $ — $ — Investments in Corporate debt securities $ — $ — $ — 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 $ — * 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.

Restructuring Activities (Table

Restructuring Activities (Tables)	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Reconciliation of severance-related accrual activity	The following is a reconciliation of the severance-related accrual activity for the year ended December 31, 2017 : Accrued Severance and Other Employee Costs Beginning Balance $ — Accrued restructuring expenses 12,105 Payments (9,576 ) Ending Balance $ 2,529

Selected Quarterly Financial 34

Selected Quarterly Financial Information (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 and 2016 : 2017 March 31 June 30 September 30 December 31 Collaboration revenue $ 1,662 $ 1,661 $ 206,654 $ — Research and development expenses 31,979 15,657 10,707 7,946 General and administrative expenses 13,159 8,552 7,059 6,913 Income (loss) from operations (43,476 ) (22,548 ) 188,888 (14,859 ) Net income (loss) attributable to common stockholders $ (43,122 ) $ (22,204 ) $ 189,073 $ (9,542 ) Basic earnings (loss) per common share $ (1.20 ) $ (0.62 ) $ 5.26 $ (0.26 ) Diluted earnings (loss) per common share $ (1.20 ) $ (0.62 ) $ 5.25 $ (0.26 ) 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 )

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Segment and Geographic Information (Details)	12 Months Ended
	Dec. 31, 2017segment
Accounting Policies [Abstract]
Number of operating segments	1
Number of reporting segments	1

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) $ in Millions	Dec. 31, 2017USD ($)
Accounting Policies [Abstract]
Cash, cash equivalents and available for sale securities	$ 167

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Collaboration Revenue (Detail) - USD ($) $ in Thousands	1 Months Ended						3 Months Ended								12 Months Ended			22 Months Ended
	Aug. 31, 2017	Jul. 31, 2017	Jun. 30, 2016	Mar. 31, 2015	Sep. 30, 2014	May 31, 2014	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2016
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront fees received	$ 16,900
Components of collaboration revenue
Total collaboration revenue							$ 0	$ 206,654	$ 1,661	$ 1,662	$ 5,322	$ 1,668	$ 28,198	$ 15,721	$ 209,977	$ 50,909	$ 51,505
License revenue
Components of collaboration revenue
Total collaboration revenue															152,912	22,937	38,083
Research and development activity revenue
Components of collaboration revenue
Total collaboration revenue															56,180	9,741	8,378
API transfer revenue
Components of collaboration revenue
Total collaboration revenue															754	18,212	5,020
Joint operating committee revenue
Components of collaboration revenue
Total collaboration revenue															$ 131	$ 19	$ 24
Novartis Pharma AG | Licensing and Commercialization Agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront fees received		$ 189,800				$ 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

Summary of Significant Accoun38

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2017
Minimum
Property and equipment
Estimated useful lives	3 years
Maximum
Property and equipment
Estimated useful lives	10 years

Summary of Significant Accoun39

Summary of Significant Accounting Policies - Share-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Apr. 30, 2016
Accounting Policies [Abstract]
Expected dividend yield	0.00%
Share-Based Compensation
Share-based compensation expense	$ 18,171	$ 31,660	$ 24,760
Research and development
Share-Based Compensation
Share-based compensation expense	11,114	21,380	16,608
General and administrative
Share-Based Compensation
Share-based compensation expense	7,057	10,280	$ 8,152
ESPP
Share-Based Compensation
Share-based compensation expense	$ 100	$ 100
ESPP | Maximum
Share-Based Compensation
Number of shares reserved for issuance under the Plan (in shares)				1,000,000

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Schedule of Weighted-Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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	81.00%	71.00%	72.00%
Risk-free interest rate, minimum	1.82%	1.14%	1.35%
Risk-free interest rate, maximum	2.38%	2.37%	2.24%
Expected term of options (years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 2 months 12 days
Expected dividend yield	0.00%	0.00%	0.00%

Net Loss Per Common Share (Deta

Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic and diluted net loss per common share calculation:
Net loss					$ 114,205	$ (193,420)	$ (105,717)
Weighted average common shares outstanding - basic (in shares)					35,919	35,486	34,580
Plus: net effect of dilutive stock options and unvested restricted stock units (in shares)					88	0	0
Weighted average common shares outstanding - dilutive (in shares)					36,007	35,486	34,580
Basic earnings (loss) per common share (in dollars per share)	$ (0.26)	$ 5.26	$ (0.62)	$ (1.20)	$ 3.18	$ (5.45)	$ (3.06)
Diluted earnings (loss) per common share (in dollars per share)	$ (0.26)	$ 5.25	$ (0.62)	$ (1.20)	$ 3.17	$ (5.45)	$ (3.06)
Anti-dilutive securities
Total (in shares)					5,361	4,080	3,297
Stock options outstanding
Anti-dilutive securities
Total (in shares)					5,179	3,359	3,009
Restricted stock units
Anti-dilutive securities
Total (in shares)					182	721	288

Cash, Cash Equivalents and Av42

Cash, Cash Equivalents and Available for Sale Securities (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash	$ 9,500,000	$ 25,800,000
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	157,400,000	108,100,000
Fair Value		$ 155,348,000
Available for sale securities with maturities of greater than one year	$ 0

Cash, Cash Equivalents and Av43

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

Cash, Cash Equivalents and Av44

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, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 38,041	$ (94,618)	$ 59,947	$ 128,537
Current period changes in fair value before reclassifications, net of tax	212	261
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0	0
Other comprehensive income (loss)	212	261	(408)
Ending balance	38,041	(94,618)	59,947
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0	(212)	(473)	$ (65)
Ending balance	$ 0	$ (212)	$ (473)

Licensing and Commercializati45

Licensing and Commercialization Agreement with Novartis Pharma AG (Details) - USD ($) $ in Thousands	1 Months Ended						3 Months Ended								12 Months Ended			22 Months Ended
	Aug. 31, 2017	Jul. 31, 2017	Jun. 30, 2016	Mar. 31, 2015	Sep. 30, 2014	May 31, 2014	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2016
Agreement
Upfront fees received	$ 16,900
Total collaboration revenue							$ 0	$ 206,654	$ 1,661	$ 1,662	$ 5,322	$ 1,668	$ 28,198	$ 15,721	$ 209,977	$ 50,909	$ 51,505
License revenue
Agreement
Total collaboration revenue															152,912	22,937	38,083
Research and development activity revenue
Agreement
Total collaboration revenue															56,180	9,741	8,378
API transfer revenue
Agreement
Total collaboration revenue															754	18,212	5,020
Joint operating committee revenue
Agreement
Total collaboration revenue															$ 131	$ 19	$ 24
Licensing and Commercialization Agreement | Novartis Pharma AG
Agreement
Upfront fees received		$ 189,800				$ 200,000
Licensing and Commercialization Agreement | Novartis Pharma AG | Achievement of specified patient enrollment milestones
Agreement
Patient enrollment-based milestone revenue achieved			$ 30,000	$ 50,000	$ 50,000													$ 130,000

Financing Agreement with Novo46

Financing Agreement with Novo A/S (Details)	1 Months Ended			19 Months Ended
	Nov. 30, 2014USD ($)	Jan. 31, 2014USD ($)	May 31, 2013USD ($)tranchepurchase	Nov. 30, 2014USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Agreement
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
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

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment
Property and equipment, gross	$ 1,345	$ 4,937
Accumulated depreciation	(827)	(1,656)
Property and equipment, net	518	3,281
Depreciation expense	$ 2,763	757	$ 698
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	$ 412	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	$ 933	1,711
Furniture and fixtures
Property and Equipment
Useful life	7 years
Property and equipment, gross	$ 0	774
Leasehold improvements
Property and Equipment
Property and equipment, gross	$ 0	$ 1,835
Leasehold improvements | Minimum
Property and Equipment
Useful life	3 years
Leasehold improvements | Maximum
Property and Equipment
Useful life	5 years

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Percent of pre-tax income:
U.S. federal statutory income tax rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	14.60%	2.80%	7.40%
Permanent items	4.00%	(1.40%)	(0.50%)
Remeasurement of deferred tax assets	49.90%	0.00%	0.00%
Impact of state rate changes	(27.90%)	(11.00%)	0.90%
Research and development credit	(0.00%)	1.90%	(0.00%)
Alternative minimum tax credit	(1.30%)	1.10%	0.00%
Change in valuation allowance	(78.60%)	(28.20%)	(29.10%)
Effective income tax rate	(4.30%)	0.20%	13.70%

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Income Tax (Benefit) Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 173	$ (23,393)	$ 136
State	(1,356)	21	91
Deferred:
Federal	(3,529)	22,966	(17,014)
State	0	0	0
Income tax benefit	$ (4,712)	$ (406)	$ (16,787)

Income Taxes - Schedule of Sign

Income Taxes - Schedule of Significant Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets (liabilities)
Deferred revenue	$ 40,961	$ 125,634
License and technology payments	8,222	10,532
Share-based compensation	17,599	16,494
Accrued expenses	608	530
Depreciation, deferred tax asset	81
Depreciation, deferred tax liability		(651)
Federal and state net operating loss carryforwards	76,309	75,177
Research and development credits	3,782	3,720
Other	3,534	2,155
Deferred income tax assets	151,096	233,591
Valuation allowance	(147,567)	(233,591)
Net deferred tax assets	$ 3,529	$ 0

Income Taxes (Details)

Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Tax Cuts and Jobs Act, Change in Tax Rate, Income Tax Expense (Benefit)	$ 3,500,000
Decrease in deferred tax asset as a result of the Tax Cuts and Jobs Act of 2017	54,600,000
Income tax benefit	4,700,000
Loss before income tax (benefit) provision	109,493,000	$ (193,826,000)	$ (122,504,000)
Federal and state tax liability, benefit from income taxes		$ 400,000
Reduction in deferred tax assets and corresponding valuation allowance	6,200,000
Refund claimed for taxes previously paid	6,500,000
Minimum
Operating Loss Carryforwards [Line Items]
Estimate of unrecognized tax benefits that may be realized over the next twelve months	0
Maximum
Operating Loss Carryforwards [Line Items]
Estimate of unrecognized tax benefits that may be realized over the next twelve months	6,900,000
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Federal net operating loss carryforwards	270,000,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Income tax benefit	$ 1,400,000

Income Taxes - Schedule of Posi

Income Taxes - Schedule of Position with Respect to Uncertain Tax Positions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Opening balance	$ 4,128
Gross amount of increases in unrecognized tax benefits during the period - current year provisions	343
Gross amount of increases in unrecognized tax benefits during the period - prior year provisions	14,430
Gross amount of increases in unrecognized tax benefits during the period - other	0
Decreases due to settlement with tax authorities during the period	(2,020)
Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period	0
Closing Balance	$ 16,881

Operating Leases (Details)

Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2017
Future minimum rental commitments under non-cancelable operating leases
2,018	$ 895
2,019	48
2,020	8
Total	951
Rent expense	$ 3,600	$ 3,000	$ 2,100
Lease Termination
Restructuring Cost and Reserve [Line Items]
Aggregate termination payments				$ 2,100

Commitments and Contingencies (

Commitments and Contingencies (Details) - License Agreements - Archemix - C5 Licensed Product - Maximum $ in Millions	Dec. 31, 2017USD ($)
Achievement of specified clinical and regulatory milestones
Commitments and contingencies
Amount to be paid on achievement of milestone	$ 57.5
First indication
Commitments and contingencies
Amount to be paid on achievement of milestone	30.5
Second and third indication
Commitments and contingencies
Amount to be paid on achievement of milestone	24.5
Sustained delivery applications
Commitments and contingencies
Amount to be paid on achievement of milestone	2.5
Achievement of specified commercial milestones
Commitments and contingencies
Amount to be paid on achievement of milestone	$ 22.5

Stock Option and Compensation55

Stock Option and Compensation Plans (Details) - USD ($)	Jan. 01, 2018	Apr. 30, 2016	Aug. 31, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Option and Compensation Plans
Options outstanding (in shares)				4,801,000
Weighted-average exercise price of options (in dollars per share)				$ 20.47
Weighted-average remaining contractual life of options				8 years 1 month 5 days
Aggregate intrinsic value of options outstanding				$ 400,000
Share-based compensation expense				$ 18,171,000	$ 31,660,000	$ 24,760,000
ESPP
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan (in shares)				983,642
Purchase price of common stock as percentage of fair market value		85.00%
Share-based compensation expense				$ 100,000	$ 100,000
Expected weighted average period to recognize share-based compensation costs				3 months
Common stock issued (in shares)				16,358	0
Proceeds from stock plans				$ 38,000
Restricted stock units
Stock Option and Compensation Plans
Share-based compensation expense				$ 300,000
RSUs expected to vest (in shares)				187,000
Weighted-average fair value of RSUs expected to vest (in dollars per share)				$ 47.25
Aggregate intrinsic value of RSUs expected to vest				$ 600,000
Total fair value vested				7,500,000
Employees | Stock options
Stock Option and Compensation Plans
Share-based compensation expense				13,100,000	$ 22,800,000	15,500,000
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures				$ 14,800,000
Expected weighted average period to recognize share-based compensation costs				2 years 6 months 4 days
Employees | Restricted stock units
Stock Option and Compensation Plans
Share-based compensation expense				$ 4,400,000	6,900,000	5,200,000
Expected weighted average period to recognize share-based compensation costs				2 years 13 days
Unrecognized compensation costs, net of estimated forfeitures				$ 5,600,000
Consultants | Non-employee Options
Stock Option and Compensation Plans
Share-based compensation expense				300,000	1,700,000	$ 4,100,000
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures				$ 200,000
Expected weighted average period to recognize share-based compensation costs				1 year 10 months 4 days
Consultants | Restricted stock units
Stock Option and Compensation Plans
Expected weighted average period to recognize share-based compensation costs				1 year 8 months 12 days
Unrecognized compensation costs, net of estimated forfeitures				$ 100,000	$ 0
Maximum | ESPP
Stock Option and Compensation Plans
Number of shares reserved for issuance under the Plan (in shares)		1,000,000
2013 Plan
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan (in shares)				492,000
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)				6,898,000
2013 Plan | Subsequent Event
Stock Option and Compensation Plans
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)	1,444,000
2013 Plan | Maximum
Stock Option and Compensation Plans
Number of shares reserved for issuance under the Plan (in shares)			3,359,641
2007 Plan
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan (in shares)			739,317

Stock Option and Compensation56

Stock Option and Compensation Plans - Summary of Stock Option Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Stock Options
Outstanding at beginning of year (in shares)	3,359	3,009	3,680
Granted (in shares)	3,024	972	764
Exercised (in shares)	(20)	(428)	(1,133)
Expired or forfeited (in shares)	(1,079)	(194)	(302)
Outstanding at end of year (in shares)	5,284	3,359	3,009
Weighted Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 39.92	$ 30.43	$ 21.03
Granted (in dollars per share)	3.50	60.40	47.31
Exercised (in dollars per share)	1.64	15.73	10.31
Expired or forfeited (in dollars per share)	38.17	48.63	34.09
Outstanding at end of year (in dollars per share)	$ 19.58	$ 39.92	$ 30.43
Options exercisable at end of year (in shares)	1,954	1,531	955
Weighted average grant date fair value (per share) of options granted during the period (in dollars per share)	$ 2.45	$ 38.18	$ 31.33

Stock Option and Compensation57

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, 2017USD ($)$ / sharesshares
Options Outstanding
Total Options Outstanding (in shares) | shares	5,284
Weighted Average Remaining Life (Years)	8 years 2 months 2 days
Weighted Average Exercise Price (in dollars per share)	$ 19.58
Aggregate Intrinsic Value of Options Outstanding | $	$ 492
Options Exercisable
Number Exercisable (in shares) | shares	1,953
Weighted Average Exercise Price (in dollars per share)	$ 35.15
Aggregate Intrinsic Value of Options Exercisable | $	$ 122
$0.12-$10.03
Options Outstanding
Total Options Outstanding (in shares) | shares	3,054
Weighted Average Remaining Life (Years)	9 years 4 months 1 day
Weighted Average Exercise Price (in dollars per share)	$ 3.68
Options Exercisable
Number Exercisable (in shares) | shares	210
Weighted Average Exercise Price (in dollars per share)	$ 6.62
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	204
Weighted Average Remaining Life (Years)	5 years 5 months 22 days
Weighted Average Exercise Price (in dollars per share)	$ 13.52
Options Exercisable
Number Exercisable (in shares) | shares	147
Weighted Average Exercise Price (in dollars per share)	$ 13.63
Exercise prices, low end of range (in dollars per share)	10.04
Exercise prices, high end of range (in dollars per share)	$ 20
$20.01-$30.00
Options Outstanding
Total Options Outstanding (in shares) | shares	127
Weighted Average Remaining Life (Years)	5 years 10 months 12 days
Weighted Average Exercise Price (in dollars per share)	$ 25.13
Options Exercisable
Number Exercisable (in shares) | shares	127
Weighted Average Exercise Price (in dollars per share)	$ 25.13
Exercise prices, low end of range (in dollars per share)	20.01
Exercise prices, high end of range (in dollars per share)	$ 30
$30.01-$40.00
Options Outstanding
Total Options Outstanding (in shares) | shares	831
Weighted Average Remaining Life (Years)	5 years 6 months 8 days
Weighted Average Exercise Price (in dollars per share)	$ 32.81
Options Exercisable
Number Exercisable (in shares) | shares	808
Weighted Average Exercise Price (in dollars per share)	$ 32.82
Exercise prices, low end of range (in dollars per share)	30.01
Exercise prices, high end of range (in dollars per share)	$ 40
$40.01-$55.00
Options Outstanding
Total Options Outstanding (in shares) | shares	708
Weighted Average Remaining Life (Years)	7 years 6 months 10 days
Weighted Average Exercise Price (in dollars per share)	$ 46.40
Options Exercisable
Number Exercisable (in shares) | shares	467
Weighted Average Exercise Price (in dollars per share)	$ 46.13
Exercise prices, low end of range (in dollars per share)	40.01
Exercise prices, high end of range (in dollars per share)	$ 55
$55.01-$73.22
Options Outstanding
Total Options Outstanding (in shares) | shares	360
Weighted Average Remaining Life (Years)	8 years 9 days
Weighted Average Exercise Price (in dollars per share)	$ 72.63
Options Exercisable
Number Exercisable (in shares) | shares	194
Weighted Average Exercise Price (in dollars per share)	$ 72.13
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 Compensation58

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, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Cash proceeds from options exercised	$ 33	$ 6,934	$ 11,473
Aggregate intrinsic value of options exercised	$ 43	$ 14,439	$ 49,255

Stock Option and Compensation59

Stock Option and Compensation Plans - Summary of Outstanding RSU Awards Granted (Details) - Restricted stock units shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Restricted Stock Units
Outstanding, beginning of period (in shares) | shares	721
Awarded (in shares) | shares	249
Vested (in shares) | shares	(341)
Forfeited (in shares) | shares	(302)
Outstanding, end of period (in shares) | shares	327
Weighted Average Grant-Date Fair Value
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 55.33
Awarded (in dollars per share) | $ / shares	4.42
Vested (in dollars per share) | $ / shares	20.15
Forfeited (in dollars per share) | $ / shares	50.30
Outstanding, end of period (in dollars per share) | $ / shares	$ 51.08

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Benefits [Abstract]
Defined contribution plan, cost recognized	$ 0.7	$ 0.8	$ 0.5

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Fair Value Measurements
Investments in U.S. Treasury securities and Corporate debt securities		$ 155,348,000
Transfer of assets from Level 1 to Level 2 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	162,457,000	108,096,000
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		120,261,000
Investments in U.S. Treasury securities and Corporate debt securities	0
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	0	35,087,000
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

Restructuring Activities (Detai

Restructuring Activities (Details) $ in Thousands	Jan. 26, 2017USD ($)	Dec. 31, 2017USD ($)employee	Jan. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Restructuring Cost and Reserve [Line Items]
Expected costs			$ 13,100
Costs expected to result in future cash expenditures		$ 12,100
Severance and other employee costs
Restructuring Cost and Reserve [Line Items]
Percent of personnel expected to be effected by reduction in workforce			80.00%
Number of employee positions eliminated in reduction of personnel | employee		122
Expected costs			$ 11,000
Cash expenditures related to reduction in personnel		$ 9,576
Severance, stock compensation and other employee costs		11,000
Accrual balance for severance and benefit costs		2,529		$ 0
Early termination payment		12,105
Severance and other employee costs | Research and development
Restructuring Cost and Reserve [Line Items]
Severance, stock compensation and other employee costs		7,500
Severance and other employee costs | General and administrative
Restructuring Cost and Reserve [Line Items]
Severance, stock compensation and other employee costs		$ 3,500
Lease termination costs
Restructuring Cost and Reserve [Line Items]
Expected costs			$ 2,100
One Penn Plaza LLC | Lease termination costs
Restructuring Cost and Reserve [Line Items]
Early termination payment	$ 900
Otsuka America Pharmaceutical, Inc. | Lease termination costs
Restructuring Cost and Reserve [Line Items]
Early termination payment	$ 1,200

Restructuring Activities - Reco

Restructuring Activities - Reconciliation of severance-related accrual activity (Details) - Severance and other employee costs $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 0
Accrued restructuring expenses	12,105
Payments	(9,576)
Ending Balance	$ 2,529

Selected Quarterly Financial 64

Selected Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Collaboration revenue	$ 0	$ 206,654	$ 1,661	$ 1,662	$ 5,322	$ 1,668	$ 28,198	$ 15,721	$ 209,977	$ 50,909	$ 51,505
Research and development expenses	7,946	10,707	15,657	31,979	59,409	50,854	48,262	37,770	66,289	196,295	131,012
General and administrative expenses	6,913	7,059	8,552	13,159	12,968	12,024	10,489	14,696	35,683	50,178	44,021
Income (loss) from operations	(14,859)	188,888	(22,548)	(43,476)	(67,055)	(61,210)	(30,553)	(36,745)	$ 108,005	$ (195,564)	$ (123,528)
Net loss attributable to common stockholders	$ (9,542)	$ 189,073	$ (22,204)	$ (43,122)	$ (66,283)	$ (60,891)	$ (29,945)	$ (36,301)
Basic earnings (loss) per common share (in dollars per share)	$ (0.26)	$ 5.26	$ (0.62)	$ (1.20)					$ 3.18	$ (5.45)	$ (3.06)
Diluted earnings (loss) per common share (in dollars per share)	$ (0.26)	$ 5.25	$ (0.62)	$ (1.20)					$ 3.17	$ (5.45)	$ (3.06)
Basic earnings (loss) per common share (in dollars per share)					$ (1.86)	$ (1.71)	$ (0.85)	$ (1.03)