Document and Entity Information Statement [Table] Statement [Line Items] Statement Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Public Float Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus CONSOLIDATED BALANCE SHEETS Assets [Abstract] Assets Assets, Current [Abstract] Current assets: Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Cash and cash equivalents at beginning of period Cash and cash equivalents Cash and cash equivalents, Amortized cost Available-for-sale Securities, Current Short-term investments Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Prepaid expenses and other current assets Assets, Current Total current assets Property, Plant and Equipment, Net Property and equipment, net Property and equipment, net Restricted Cash and Cash Equivalents, Noncurrent Restricted cash Letter of credit secured in connection with the lease, included in restricted cash Other Assets, Noncurrent Other assets Assets Total assets Liabilities and Equity [Abstract] Liabilities and stockholders' equity Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Current Accounts payable Accrued Liabilities, Current Accrued expenses Accrued expenses Deferred Compensation Share-based Arrangements, Liability, Current Liability classified stock-based compensation awards Liabilities, Current Total current liabilities Other Liabilities, Noncurrent Other liabilities Stockholders' Equity Attributable to Parent [Abstract] Stockholders' equity Preferred Stock, Value, Issued Preferred stock, $0.0001 par value; 5,000 shares authorized, no shares issued and outstanding at December 31, 2016 and 2015, respectively Common Stock, Value, Issued Common stock, $0.0001 par value; 100,000 shares authorized, 36,992 and 36,941 shares issued and outstanding at December 31, 2016 and 2015, respectively Additional Paid in Capital, Common Stock Additional paid-in capital Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income Retained Earnings (Accumulated Deficit) Deficit accumulated during the development stage Accumulated deficit Stockholders' Equity Attributable to Parent Balance Balance Total stockholders' equity Liabilities and Equity Total liabilities and stockholders' equity Preferred Stock, Par or Stated Value Per Share Preferred stock, par value (in dollars per share) Preferred Stock, Shares Authorized Preferred stock, shares authorized Preferred Stock, Shares Issued Preferred stock, shares issued Preferred Stock, Shares Outstanding Preferred stock, shares outstanding Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Balance (in shares) Balance (in shares) Common stock, shares issued Common Stock, Shares, Outstanding Common stock, shares outstanding CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS Operating Expenses [Abstract] Operating expenses: Research and Development Expense Research and development Research and development expense General and Administrative Expense General and administrative Operating Expenses Total operating expenses Operating Income (Loss) Loss from operations Loss from operations Investment Income, Interest Interest income Net Income (Loss) Available to Common Stockholders, Basic Net loss Net loss Earnings Per Share, Basic and Diluted Net loss per share - basic and diluted Weighted Average Number of Shares Outstanding, Basic and Diluted Weighted-average number of common shares used in net loss per share—basic and diluted Weighted-average number of common shares used in net loss per share-basic and diluted Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Unrealized gain (loss) on available-for-sale marketable securities Unrealized (loss) gain on available-for-sale securities Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive loss CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common stock Additional Paid In Capital [Member] Additional paid-in capital Accumulated Other Comprehensive Income [Member] Accumulated other comprehensive (loss) income Retained Earnings [Member] Accumulated deficit Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity Stock Issued During Period, Value, New Issues Fair value of common stock issued Issuance of common stock, net of issuance costs Stock Issued During Period, Shares, New Issues Number of shares of common stock issued Issuance of common stock, net of issuance costs (in shares) Stock Issued During Period, Value, Restricted Stock Award, Gross Vesting of restricted stock Stock Issued During Period, Shares, Restricted Stock Award, Gross Vesting of restricted stock (in shares) Stock Issued During Period, Value, Stock Options Exercised Issuance of common stock resulting from exercise of stock options Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Exercised (in shares) Issuance of common stock resulting from exercise of stock options (in shares) Restricted Stock, Value, Shares Issued Net of Tax Withholdings Issuance of common stock resulting from vesting of restricted stock units and payment of tax withholdings Restricted Stock, Shares Issued Net of Shares for Tax Withholdings Issuance of common stock resulting from vesting of restricted stock units and payment of tax withholdings (in shares) The fair value of stock issued to purchase technology rights. Issuance of Common Stock to Purchase Technology Rights Shares issued for technology rights Represents the common stock issued to purchase technology rights. Common Stock Issued To Purchase Technology Rights Shares issued for technology rights (in shares) Stock-based compensation expense Stock-based compensation expense Adjustments to additional paid-in capital Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Issuance of common stock, issuance costs CONSOLIDATED STATEMENTS OF CASH FLOWS Net Cash Provided by (Used in) Operating Activities Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net loss to net cash used in operating activities: Depreciation, Depletion and Amortization Depreciation and amortization Share-based Compensation Stock-based compensation expense Accretion (Amortization) of Discounts and Premiums, Investments Amortization of premiums and discounts on available-for-sale marketable securities The fair value of stock issued in exchange for certain intellectual property rights. Issuance of Common Stock in Exchange for License Non-cash expense related to purchase of technology rights Gain (Loss) on Disposition of Assets Loss on disposal of fixed assets Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses, other current assets and other assets Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accrued Liabilities and Other Operating Liabilities Accrued expenses and other liabilities Increase (Decrease) in Deferred Compensation Liability classified stock-based compensation awards Increase (decrease) in stock-based compensation award liability Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash used in operating activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Investing activities Payments to Acquire Property, Plant, and Equipment Purchases of property and equipment Payments to Acquire Available-for-sale Securities Purchase of investments Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities Maturities of investments Increase (Decrease) in Restricted Cash Decrease (increase) in restricted cash Net Cash Provided by (Used in) Investing Activities, Continuing Operations Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Financing activities Proceeds from Stock Options Exercised Proceeds from the exercise of stock options Proceeds from Issuance of Common Stock Net proceeds from the issuance of common stock and restricted common stock Proceeds from issuance of common stock Payments Related to Tax Withholding for Share-based Compensation Cash used to settle restricted stock liability Cash used to settle tax on restricted stock liability awards Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Continuing Operations Increase (decrease) in cash and cash equivalents Noncash Investing and Financing Items [Abstract] Supplemental disclosure of non-cash investing and financing activities The cash inflow from the additional capital contribution to the entity, included in prepaid expenses and other current assets. Proceeds from the issuance of common stock included in prepaid expenses and other current assets Proceeds from the issuance of common stock included in prepaid expenses and other current assets Purchases of property and equipment in accounts payable Purchase of property and equipment in accounts payable Nature of business Nature of Operations [Text Block] Nature of business Significant accounting policies. Basis of Presentation and Significant Accounting Policies [Text Block] Significant accounting policies Property and equipment Property, Plant and Equipment Disclosure [Text Block] Property and equipment Prepaid expenses and other current assets Other Current Assets [Text Block] Prepaid expenses and other current assets Accrued expenses Accounts Payable and Accrued Liabilities Disclosure [Text Block] Accrued expenses Common stock. Stockholders' Equity Note Disclosure [Text Block] Common stock Stock-based compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock-based compensation Income taxes Income Tax Disclosure [Text Block] Income taxes Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies License agreements The entire disclosure for license agreements entered into by the entity. License Agreements Disclosure [Text Block] License agreements Employee benefit plan Pension and Other Postretirement Benefits Disclosure [Text Block] Employee benefit plan Reduction in force Restructuring and Related Activities Disclosure [Text Block] Reduction in force Quarterly Financial Information (unaudited, in thousands, except per share data) Quarterly Financial Information [Text Block] Quarterly Financial Information Subsequent Events. Subsequent Events [Text Block] Subsequent Events Consolidation, Policy [Policy Text Block] Basis of consolidation Use of Estimates, Policy [Policy Text Block] Use of estimates Segment Reporting, Policy [Policy Text Block] Segment and geographic information Cash and Cash Equivalents, Policy [Policy Text Block] Cash and cash equivalents Fair Value of Financial Instruments, Policy [Policy Text Block] Fair value of financial instruments Marketable Securities, Available-for-sale Securities, Policy [Policy Text Block] Investments Description of financial instruments, excluding certain derivatives, with off-balance sheet credit risk (for example, standby letters of credit or financial guarantees), including (1) information about the (shared) activity, region or economic characteristic that identifies the concentration, (2) the face or contract amount of the instrument, (3) the nature and terms of the instrument, including the market risk, cash requirements and accounting policies for it, (4) the maximum amount of loss due to credit risk that would be incurred if the counterparties failed completely to perform according to the terms of the contracts, and any security or collateral that proved to be of no value, (5) the entity's policy of requiring collateral or other security to support financial instruments subject to credit risk, information about access to collateral or other security, and a brief description of the security supporting those financial instruments, and (6) the policy of entering into and a brief description of master netting arrangements to mitigate the credit risk, and the extent to which such arrangements would reduce the maximum amount of loss due to credit risk. Concentration Of Credit Risk And Off Balance Sheet Risk Policy Text Block Concentrations of credit risk and off-balance sheet risk Property, Plant and Equipment, Policy [Policy Text Block] Property and equipment Disclosure of accounting policy for prepaid expenses relating to a license agreement included in other assets. Other Assets [Policy Text Block] Other assets Research and Development Expense, Policy [Policy Text Block] Research and development costs Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Stock-based compensation Income Tax, Policy [Policy Text Block] Income taxes Earnings Per Share, Policy [Policy Text Block] Net loss per share New Accounting Pronouncements, Policy [Policy Text Block] Recent Accounting Pronouncements Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Schedule of information about financial assets and liabilities measured at fair value Marketable Securities [Table Text Block] Schedule of cash, cash equivalents and investments Tabular disclosure of the estimated useful life of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. Property Plant and Equipment Estimated Useful Lives [Table Text Block] Schedule of estimated useful lives of the assets Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of potentially anti-dilutive securities excluded from calculation of diluted net loss per share Property, Plant and Equipment [Table Text Block] Schedule of property equipment and related accumulated depreciation Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block] Schedule of prepaid expenses and other current assets Schedule of Accrued Liabilities [Table Text Block] Schedule of accrued expenses Tabular disclosure of the shares of common stock reserved for the potential conversion of outstanding preferred stock and the exercise of stock options. Schedule of Shares of Common Stock Reserved for Potential Conversion [Table Text Block] Schedule of shares of common stock reserved for the issuance of common stock for vested restricted stock units and the exercise of stock options Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Stock-based compensation Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Schedule of stock-based compensation expense as reflected in the Company's consolidated statements of operations and comprehensive loss Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of stock option activity and related information Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of assumptions used to estimate fair value of each stock option on grant date Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Schedule of restricted stock units Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of principal components of deferred tax assets Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of minimum aggregate future lease commitments Schedule of Quarterly Financial Information [Table Text Block] Schedule of Quarterly Financial Information Cash, Cash Equivalents, and Short-term Investments Cash, cash equivalents, and investments Total cash, cash equivalents, and investments, Fair Value Substantial Doubt about Going Concern, within One Year Substantial doubt about the ability to continue as a going concern Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Hierarchy [Axis] Fair Value Measurements Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value Inputs Level1 [Member] Level 1 Fair Value Inputs Level2 [Member] Level 2 Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair value of financial instruments Segment and Geographic Information [Abstract] Segment and geographic information Number of Operating Segments Number of operating segments Assets, Fair Value Disclosure [Abstract] Financial assets Cash and Cash Equivalents, Fair Value Disclosure Cash equivalents Cash and cash equivalents, Fair value Available-for-sale Securities Short-term investments Investments, Fair Value Assets, Fair Value Disclosure Total financial assets Liabilities, Fair Value Disclosure [Abstract] Financial liabilities Financial and Nonfinancial Liabilities, Fair Value Disclosure Total financial liabilities Schedule of Investments [Table] Cash and Cash Equivalents [Axis] Restricted Cash And Cash Equivalents Cash And Cash Equivalents [Member] Cash and Cash Equivalents [Domain] Cash And Cash Equivalents [Member] Cash and money market accounts U S Government Sponsored Enterprises Debt Securities [Member] Government-sponsored enterprise securities Major Types of Debt and Equity Securities [Axis] Major Types Of Debt And Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] U S Treasury Securities [Member] Treasury securities Debt security, in which the authorized issuer owes the holder a debt and is obliged to repay the principal and interest (the coupon) and unsecured promissory note (generally negotiable) that provides institutions with short-term funds. Corporate Bonds And Commercial Paper [Member] Corporate bonds and commercial paper Schedule of Investments [Line Items] Investments Represents the original period of maturity of securities, corporate bonds and commercial paper classified as cash and cash equivalents in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Cash and Cash Equivalents Maturity Period Original maturity period, cash and cash equivalents Represents the maturity period for investments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Maturity Period, Investments Maturity period, investments Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract] Amortized cost Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Basis Due within 1 year Available-for-sale Securities, Amortized Cost Basis Investments, Amortized Cost Amortized cost of cash and cash equivalents and short-term investments generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable. Cash, Cash Equivalents, and Short-term Investments, Amortized Cost Total cash, cash equivalents, and investments, Amortized Cost Available-for-sale Securities, Gross Unrealized Gain [Abstract] Gross unrealized gains Available for Sale Securities, Accumulated Gross Unrealized Gain before Tax Gross unrealized gains Available-for-sale Securities, Gross Unrealized Loss [Abstract] Gross unrealized losses Available for Sale Securities Accumulated Gross Unrealized Loss before Tax Gross unrealized losses Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract] Fair value Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value Due within 1 year Other than Temporary Impairment Losses, Investments, Available-for-sale Securities Charges for other-than-temporary declines in fair value of short-term or long-term investments Available-for-sale Securities, Gross Realized Gain (Loss) Realized gains or losses on investments Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property Plant And Equipment Type [Domain] Property, Plant and Equipment, Type [Domain] Equipment [Member] Laboratory equipment Furniture And Fixtures [Member] Furniture and fixtures Computer Equipment [Member] Computer equipment Property, Plant and Equipment [Line Items] Property and equipment Concentrations of Credit Risk and Off Balance Sheet Risk [Abstract] Concentrations of credit risk and off-balance sheet risk Represents the number of financial institutions in which cash, cash equivalents and investments were deposited. Number of Financial Institutions in which Cash, Cash Equivalents and Investments were Deposited Number of financial institutions in which cash, cash equivalents and investments were deposited Property, Plant and Equipment, Useful Life Estimated useful lives Other Assets [Abstract] Other assets Prepaid Expense, Noncurrent Prepaid CRO Expenses Share-based Compensation [Abstract] Share-based compensation Represents the number of companies the expected volatility is based using the Black-Scholes option pricing model. Number of Companies Expected Volatility is Based Number of companies expected volatility is based Represents the number of companies with similar characteristics to the entity that are included in the computation of expected volatility. Number Of Companies With Similar Characteristics To Entity Included In Expected Volatility Computation Number of companies with similar characteristics to the Company included in computation Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities Name [Domain] Antidilutive Securities, Name [Domain] An arrangement whereby an employee or non-employee is entitled to receive in the future, subject to vesting and other restrictions, a number of shares in the entity at a specified price, as defined in the agreement. Although there are variations, normally, after vesting, when an option is exercised, the employee-holder pays the strike value in cash to the issuing employer-entity and receives equity shares. The equity shares can be sold into the market for cash at the current market price without restriction. Options may be used to attract, retain and incentivize employees, in addition to their regular salary and other benefits. Employee And Non Employees Stock Option [Member] Outstanding stock options Restricted Stock Units R S U [Member] Restricted Stock Units Warrant [Member] Outstanding warrants Restricted Stock [Member] Restricted Common Stock Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Net loss per share Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Potentially anti-dilutive securities excluded from calculation of diluted net loss per share (in shares) Leasehold Improvements [Member] Leasehold improvements Property, Plant and Equipment, Gross Property and equipment, gross Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less: accumulated depreciation Interest Receivable, Current Interest receivable Carrying amount as of the balance sheet date of amounts paid in advance to research contract organizations. Prepaid Contract Research Organizations, Current Prepaid contract research organization costs Prepaid Insurance Prepaid insurance Other Prepaid Expense, Current Prepaid other Carrying value as of the balance sheet date of obligations incurred through that date and payable for contract research organizations. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Contract Research Organizations, Current Contract research organization costs Employee-related Liabilities, Current Compensation and related benefits Carrying value as of the balance sheet date of obligations incurred through that date and payable for consulting fees. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accrued Consulting Fees Current Consulting fees Accrued Professional Fees, Current Professional fees Deferred Rent Credit, Current Deferred rent Other Accrued Liabilities, Current Other Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Award Type [Axis] Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain] Equity Award [Domain] Stock Compensation Plan [Member] Equity compensation plans Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Represents about inducement award program established in accordance with NASDAQ Listing Rule 5635(c)(4). Inducement Award Program [Member] Inducement Award Program Counterparty Name [Axis] Repurchase Agreement Counterparty Name [Domain] Counterparty Name [Domain] Represents information pertaining to Encarta, Inc. Encarta Inc [Member] Encarta, Inc. Subsidiary, Sale of Stock [Line Items] Common stock Common Stock, Capital Shares Reserved for Future Issuance Shares reserved for issuance Represents the number of votes entitled per each share of common stock. Number of Votes Per Each Share of Common Stock Number of votes entitled for each share of common stock Proceeds from Issuance or Sale of Equity [Abstract] At-the-market equity offering program The maximum value of common stock able to be offered and sold through the market equity offering program. Maximum Value Of Common Stock Offered Through Market Equity Offering Program Maximum value of common stock allowed to be sold n/a Warrant Abstract Warrant Class of Warrant or Right, Number of Securities Called by Warrants or Rights Number of shares of common stock in the warrant issued under the license agreement Number of shares of common stock in the warrant issued Class of Warrant or Right, Exercise Price of Warrants or Rights Exercise price of shares of common stock in the warrant issued under the license agreement (in dollars per share) Exercise price of shares of common stock in the warrant issued (in dollars per share) Period representing the expiration period of warrant. Class Of Warrant Or Right Expiration Period Expiration period of warrant Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Research And Development Expense [Member] Research and development General And Administrative Expense [Member] General and administrative Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] Stock-based compensation Allocated Share-based Compensation Expense Total stock-based compensation expense Stock-based compensation expense Represents the number of equity compensation plans of the entity. Number of Equity Compensation Plans Number of equity compensation plans Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Vesting percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Expiration term Represents the 2012 Incentive Plan of the entity. Incentive Plan2012 [Member] 2012 Plan Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Number of shares reserved Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Additional number of shares authorized for issuance Represents the annual increase in the maximum number of shares (or other type of equity) that was initially approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. Share Based Compensation, Arrangement by Share Based Payment Award, Annual Increase in Number of Shares Authorized Annual increase in number of shares reserved Represents the percentage of the number of shares of outstanding stock relating to determining the annual increase in the maximum number of shares available for issuance under the plan. Share Based Compensation, Arrangement by Share Based Payment Award, Percentage of Outstanding Common Stock for Computation of Annual Increase in Number of Shares Reserved Percentage of outstanding shares of common stock used to compute annual increase in number of shares reserved Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Shares available for future grants Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Shares Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Outstanding at the end of the period (in shares) Outstanding at the beginning of the period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period Forfeited/cancelled (in shares) Represents the number of shares which fully vested under the plan, as of the balance sheet date. Share Based Compensation Arrangement by Share Based Payment Award Options, Vested Number Vested at the end of the period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Vested and expected to vest at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Weighted-average exercise price per share Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Outstanding at the end of the period (in dollars per share) Outstanding at the beginning of the period (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Granted (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Exercised (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Forfeited/cancelled (in dollars per share) Represents the weighted-average exercise price for outstanding stock options that are fully vested, as of the balance sheet date. Share Based Compensation Arrangement by Share Based Payment Award, Options Vested Weighted Average Exercise Price Vested at the end of the period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Vested and expected to vest at end of the period (in dollars per share) Share Based Compensation Arrangement by Share Based Payment Award, Options Weighted Average Remaining Contractual Term [Abstract] Weighted-average remaining contractual term Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Outstanding at the end of the period Represents the weighted average remaining contractual term for fully vested options outstanding. Share Based Compensation Arrangement by Share Based Payment Award, Options Vested Weighted Average Remaining Contractual Term Vested at the end of the period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Vested and expected to vest at the end of the period Share-based Compensation Arrangement by Share-based Payment Award Options Aggregate Intrinsic Value [Abstract] Aggregate intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Outstanding at the end of the period (in dollars) Represents the amount of difference between fair value of the underlying shares reserved for issuance and exercise prices of fully vested options outstanding. Share-based Compensation Arrangement by Share-based Payment Award Options Vested Intrinsic Value Vested at the end of the period (in dollars) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Vested and expected to vest at end of the period (in dollars) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Assumptions used to estimate fair value of each stock-based award on the grant date Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Risk-free interest rate (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Volatility (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected term Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Additional disclosures Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted-average grant date fair value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value Fair value of vested stock options Represents the total fair value of options granted during the reporting period. Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Total Grant Date Fair Value Grant date fair value of options Percentage of performance conditions achieved during the period. Share Based Compensation Arrangement By Share Based Payment Award Options Percentage Of Performance Conditions Percentage of performance conditions achieved Percentage of performance conditions not considered probable of achievement. Share Based Compensation Arrangement By Share Based Payment Award Option Percentage of Performance Conditions Not Considered Probable of Achievement Percentage of performance conditions not considered probable of achievement Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options Total unrecognized stock-based compensation expense (in dollars) Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Weighted-average recognition period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Unvested at the end of the period (in shares) Unvested at the beginning of the period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Weighted-average grant date fair value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Unvested at the end of the period (in dollars per share) Unvested at the beginning of the period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Additional disclosures Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Fair value of shares vested Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options Unrecognized stock-based compensation expense Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Shares issued Represents the percentage of stock awards vesting each year. Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Percentage Per Year Vesting percentage per year The number of non-vested equity-based payment instruments, excluding stock (or unit) options, which had its terms amended and that validly exist and are outstanding as of the balance sheet date. Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number With Amended Terms Unvested RSUs with amended terms Vesting period for quarterly installments. Vesting Period For Quarterly Installments Vesting period for quarterly installments Operating Loss Carryforwards [Table] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Internal Revenue Service I R S [Member] Federal State And Local Jurisdiction [Member] State Operating Loss Carryforwards [Line Items] Operating loss carryforwards Operating Loss Carryforwards Net operating loss carryforwards Tax Credit Carryforward [Table] Tax Credit Carryforward [Line Items] Tax credit carryforwards Tax Credit Carryforward, Amount Tax credits Represents the testing period for changes in ownership interest of significant shareholders for determining the limitations on the use of all operating loss and tax credit carryforwards available to reduce future taxable income. Operating Loss and Tax Credit Carryforwards Limitations on Use Testing Period for Changes in Ownership Interest of Significant Shareholders Testing period for changes in ownership interest of significant shareholders Effective Income Tax Rate Reconciliation, Percent [Abstract] Reconciliation of income taxes computed using the U.S. federal statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Income tax benefit using U.S. federal statutory rate (as a percent) Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent State tax benefit, net of federal benefit (as a percent) Effective Income Tax Rate Reconciliation, Tax Credit, Research, Percent Research and development tax credits (as a percent) Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent Permanent items (as a percent) Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Change in the valuation allowance (as a percent) Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Other (as a percent) Effective Income Tax Rate Reconciliation, Percent Effective income tax rate (as a percent) Components of Deferred Tax Assets [Abstract] Deferred tax assets: Deferred Tax Assets, Operating Loss Carryforwards Net operating loss carryforwards Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from capitalized research and development. Deferred Tax Assets Capitalized Research and Development Capitalized research and development Deferred Tax Assets, Tax Credit Carryforwards, Research Research and development credits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost Stock-based compensation Deferred Tax Assets, Other Other Deferred Tax Assets, Gross Gross deferred tax assets Deferred Tax Assets, Valuation Allowance Valuation allowance Deferred Tax Assets, Net of Valuation Allowance Net deferred tax asset Other Income Tax Expense (Benefit), Continuing Operations [Abstract] Additional disclosures Valuation Allowance, Deferred Tax Asset, Change in Amount Increase in valuation allowance Unrecognized Tax Benefits Unrecognized tax benefits Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Interest and penalties accrued related to unrecognized tax benefits Represents the amount recognized for uncertain tax positions as of the balance sheet date. Liability for Uncertain Tax Positions Uncertain tax positions Schedule of Operating Leased Assets [Table] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Letter Of Credit [Member] Letter of credit Lease Arrangement, Type [Axis] Lease Arrangement Type [Domain] Lease Arrangement, Type [Domain] Represents information relating to a lease agreement for office and laboratory space in Needham, Massachusetts. Office And Laboratory Space In Needham Massachusetts [Member] Office and Laboratory Space in Needham, Massachusetts Operating Leased Assets [Line Items] Operating Leased Assets Area of Real Estate Property Area of space Operating Leases, Rent Expense, Minimum Rentals Initial annual base rent Represents the period after which base rent increases under operating leases. Operating Leases Period after Which Base Rent Increases Period after which base rent increases Represents the amount of lease rent expense for last period. Operating Leases Rent Expense for Last Period Base rent for last twelve-month period Payments for (Proceeds from) Tenant Allowance Tenant improvement allowance received Security Deposit Security deposit Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Minimum aggregate future lease commitments Operating Leases, Future Minimum Payments Due, Next Twelve Months 2017 Operating Leases, Future Minimum Payments, Due in Two Years 2018 Operating Leases, Future Minimum Payments, Due in Three Years 2019 Operating Leases, Future Minimum Payments Due Total Operating Leases, Rent Expense, Net Rent expense Schedule of Collaborative Arrangements and Non-collaborative Arrangement Transactions [Table] Type of Arrangement and Non-arrangement Transactions [Axis] Arrangements And Nonarrangement Transactions [Member] Arrangements and Non-arrangement Transactions [Domain] Represents the exclusive license agreement entered into by the entity. Exclusive License Agreement [Member] Exclusive license agreement Represent the information pertaining to Infinity. Infinity [Member] Infinity Represents information pertaining to Pfizer Inc. Pfizer Inc [Member] PFIZER Represents information pertaining to The Scripps Research Institute. The Scripps Research Institute [Member] Scripps Range [Axis] Range [Member] Range [Domain] Maximum [Member] Maximum Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] License agreements Represents the amount of assumption of financial responsibility by licensor for the shutdown of certain specified clinical studies. Collaborative And License Arrangements, Maximum Exposure On Shut Down Of Clinical Studies Maximum exposure by licensor Represents the amount of milestone payments to be made upon the completion of DUO study under the agreement. Collaborative And License Arrangements, Payments On Completion of D U O Study Payments on completion of D U O Study Represents the amount of milestone payments to be made upon the approval of the new drug application or an application for marketing authorization with a regulatory authority outside of the United States for a product per the agreement. Collaborative And License Arrangements, Payments On Approval of New Drug Application Payments on approval of new drug application Represents the multiplier for issuance of common stock relating to license agreement. Collaborative And License Arrangements, Multiplier For Issuance Of Common Stock Multiplier for issuance of common stock Period of time for computing the average closing price of a share of common stock as quoted on NASDAQ following the public announcement of the applicable milestone event, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Collaborative Arrangements Period of Time for Average Closing Price of Share of Common Stock Period for computing average closing price Represents the product's royalty obligations term that begin on the date of first commercial sale of the product. Collaborative Arrangements Royalty Obligations Term Royalty obligations term Represents the percentage of reduction in royalty on net sales under the license agreement. Collaborative And License Arrangements, Percentage of Reduction In Royalty On Net Sales Percentage of reduction in royalty on net sales Represents the deduction in royalty payments as a percentage of amount paid to third party per license agreement. Collaborative Arrangements, Deduction in Royalty Payments as Percentage of Amount Paid to Third Party Deduction in royalty payments as percentage of amount paid to third party Represents the maximum reduction percentage of royalties per license agreement. Collaborative Arrangements Maximum Reduction Percentage Percentage royalty reductions capped Represents the percentage of additional royalty on worldwide net sales entity is obligated to pay per license agreement. Collaborative Arrangements Percentage of Additional Royalty Percentage of additional royalty on worldwide net sales Represents the percentage of net sales in the United States for royalty obligations after full reimbursement by entity per license agreement. Collaborative Arrangements Percentage of United States Royalty Obligations Percentage of net sales for royalty obligations in the United States Represents the percentage of reduction of royalty rate on a product-by product and country-by-country basis applicable if the royalty is payable solely on the basis of non-patent regulatory exclusivity. Collaborative Arrangements Percentage of Royalty Reduction Non Patent Regulatory Exclusivity Percentage of reduction of royalty rate on basis of non-patent regulatory exclusivity The number of products required to be provided to the entity from licensor with an initial quantity of clinical supply for an agreed upon price. Number of Products Required With Initial Quantity of Clinical Supply from Third Party for Agreed Upon Price Number of products required from licensor for an agreed upon price Represents the one-time cash payment made under the agreement. Collaborative Arrangements One Time Cash Payment One-time cash payment Represents the eligible amount of payable in developmental milestones under the agreement by the entity. Collaborative Arrangements Payable on Developmental Milestones Eligible amount payable on developmental milestones to Pfizer Represents the additional amount to be payable on successful attainment of regulatory and commercial sales milestones. Collaborative Arrangements Additional Payable on Successful Attainment of Regulatory and Commercial Sales Milestones Additional payable on successful attainment of regulatory and commercial sales milestones Payments to Acquire Productive Assets Cash payment under the agreement Sale of Stock, Price Per Share Share price (in dollars per share) Represents the total amount of milestone payments made upon the achievement of specified regulatory and commercialization milestones under the agreement. Collaborative Arrangements Milestone Payments upon Achievement of Regulatory and Commercialization Milestones Milestone payments triggered upon the achievement of specified regulatory and commercialization milestones Defined Contribution Plan, Cost Recognized Contributions made under 401(k) plan Schedule of Restructuring and Related Costs [Table] Restructuring Type [Axis] Type Of Restructuring [Domain] Type of Restructuring [Domain] Employee Severance [Member] Employee Severance Restructuring Cost and Reserve [Line Items] Restructuring Costs Restructuring and Related Cost, Number of Positions Eliminated, Period Percent Reduction of workforce (as a percent) Entity Number of Employees Number of full time employees Restructuring and Related Cost, Expected Cost Estimated one- time severance and related costs Payments for Restructuring Severance paid Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent events Subsequent Event [Line Items] Subsequent events Line of Credit Facility, Maximum Borrowing Capacity Maximum borrowing capacity Number of separate advances under the debt agreement. Line of Credit Facility Number of Separate Advances Number of separate advances Represents the period after milestone event per debt agreement. Period After Milestone Event Period after milestone event Debt Instrument, Interest Rate, Stated Percentage Interest rate Debt Instrument, Basis Spread on Variable Rate Basis spread Represents the minimum cash proceeds to extend interest only payment period. Minimum Cash Proceeds To Extend Interest Only Payment Period Minimum cash proceeds to extend interest only payment period Represents the number of monthly installments of principal and interest amortization payments. Amortization Payments number Of Installments Amortization payments, installments Represents the number of business day for prior written notice for prepayment. Number Of Business Days Prior Written Notice For Prepayment Number of business days prior written notice for prepayment Represents the percentage of prepayment charge per debt agreement. Percentage Of Prepayment Charge Prepayment charge (as a percent) Represents the percentage of total principal amount as final payment. Debt Instrument Percentage Of Total Principal Amount As Final Payment Percentage of total principal amount, as final payment Represents the threshold for the final payment relating to debt agreement. Debt Instrument Final Payment Threshold Threshold for final debt payment Represents the additional interest rate in event of default. Debt Instrument Additional Interest Rate In Event Of Default Additional interest rate in an event of default Sale of Stock [Axis] Sale Of Stock Name Of Transaction [Domain] Sale of Stock [Domain] Sale of stock by a private company to the public, excluding the first sale of stock by the company. Follow On Offerings [Member] Follow-on offering Represents information relating to the at-the-market equity offering program of the entity. At Market Equity Offering Program [Member] At The Market Equity Offering Program Measurement Frequency [Axis] Fair Value Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value Measurements Recurring [Member] Recurring basis Measurement Basis [Axis] Portion At Fair Value Fair Value Disclosure [Member] Portion at Fair Value Measurement [Member] Estimate Of Fair Value Fair Value Disclosure [Member] Total Maturity Overnight And On Demand [Member] Overnight repurchase agreements Vesting [Axis] Vesting [Domain] Vesting [Domain] Share Based Compensation Award Tranche One [Member] One year from vesting Share Based Compensation Award Tranche Two [Member] Each successive three-month period, thereafter Performance Shares [Member] Performance shares Share Based Compensation Award Tranche Three [Member] Vesting Immediately Fourth portion of share-based compensation award differentiated by a particular vesting feature, including, but not limited to, performance measure or service period. Share Based Compensation Award Tranche Four [Member] Vesting ratably in quarterly installments Over Allotment Option [Member] Underwriters' option Represents information pertaining to term loan facility. Term Loan Facility [Member] Term loan Scenario [Axis] Scenario Unspecified [Domain] Scenario, Unspecified [Domain] Represents information pertaining to first tranche drawn on closing date. First Tranche Drawn On Closing Date [Member] First tranche drawn on closing date Represents information pertaining to the second tranche of the debt agreement. Debt Instrument Second Tranche [Member] Second tranche Represents information pertaining to the third tranche of the debt agreement. Debt Instrument Third Tranche [Member] Third tranche Represents information pertaining to the second and third tranches of the debt agreement. Debt Instrument Second And Third Tranche [Member] Second and third tranches Represents information pertaining to the fourth tranche of the debt agreement. Debt Instrument Fourth Tranche [Member] Fourth tranche Represents pertaining to interest-only payments being extended by six months. Debt Instrument Interest Only Payments Extended [Member] Interest-only payments extended Represents information pertaining to advance prepaid within 12 months following closing date. Advance Prepaid Within Twelve Months Following Closing Date [Member] Advance prepaid within 12 months following closing date Represents information pertaining to advance prepaid between 12 months and 24 months following closing date. Advance Prepaid Between Twelve And Twenty Four Months Following Closing Date [Member] Advance prepaid between 12 months and 24 months following closing date Represents information pertaining to advance prepaid after 24 months. Advance Prepaid After Twenty Four Months Following Closing Date [Member] Advance prepaid after 24 months Minimum [Member] Minimum Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Prime Rate [Member] Prime rate