This concept does not have a custom type definition. Document and Entity Information [Abstract] Statement [Table] Statement [Line Items] Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Current Reporting Status Entity Filer Category Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Statement of Financial Position [Abstract] Assets [Abstract] Assets, Current [Abstract] Current assets: Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Cash and cash equivalents Available-for-sale Securities, Debt Securities, Current Investments, available-for-sale Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Assets, Current Total current assets Available-for-sale Securities, Debt Securities, Noncurrent Investments, available-for-sale Property, Plant and Equipment, Net Property and equipment, net Restricted Cash and Cash Equivalents, Noncurrent Restricted cash Restricted cash included in long-term assets Other Assets, Noncurrent Other assets Assets Total assets Liabilities and Equity [Abstract] Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Current Accounts payable Accrued Liabilities, Current Accrued expenses Contract with Customer, Liability, Current Current portion of deferred revenue Deferred revenue, current portion Lease Incentive, Payable, Current Current portion of lease incentive obligation Loans Payable to Bank, Current Current portion of term loan payable Liabilities, Current Total current liabilities Deferred Rent Credit, Noncurrent Deferred rent, net of current portion Contract with Customer, Liability, Noncurrent Deferred revenue, net of current portion Deferred revenue, net of current portion This item represents an incentive or inducement contractually stipulated between parties to a lease whereby the lessor has committed to provide the entity (lessee) with a cash payment as inducement to enter the lease. Used to reflect the noncurrent portion of the liabilities. Lease Incentive Payable Noncurrent Lease incentive obligation, net of current portion Other Liabilities, Noncurrent Other long term liabilities Commitments and Contingencies Commitments (Note 10) Stockholders' Equity Attributable to Parent [Abstract] Stockholders’ equity: Preferred Stock, Value, Outstanding Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued and outstanding Common Stock, Value, Issued Common stock, $0.001 par value; 120,000,000 shares authorized; 43,883,774 and 43,577,526 shares issued and outstanding at June 30, 2018 and December 31, 2017, respectively; Additional Paid in Capital Additional paid-in capital Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Retained Earnings (Accumulated Deficit) Accumulated deficit Stockholders' Equity Attributable to Parent Total stockholders’ equity Liabilities and Equity Total liabilities and stockholders’ equity Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract] Preferred Stock Disclosures Preferred Stock, Par or Stated Value Per Share Preferred stock, par value (in dollars per share) Preferred Stock, Shares Authorized Preferred stock, shares authorized (in shares) Preferred Stock, Shares Issued Preferred stock, shares issued (in shares) Preferred Stock, Shares Outstanding Preferred stock, shares outstanding (in shares) Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] Common Stock Disclosures Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Common Stock, Shares Authorized Common stock, shares authorized (in shares) Common Stock, Shares, Issued Common stock, shares issued (in shares) Common Stock, Shares, Outstanding Common Stock, shares outstanding (in shares) Income Statement [Abstract] Revenues [Abstract] Revenues Revenue from Contract with Customer, Including Assessed Tax Collaboration revenue Operating Expenses [Abstract] Operating expenses: Research and Development Expense Research and development General and Administrative Expense General and administrative Operating Expenses Total operating expenses Nonoperating Income (Expense) [Abstract] Other income (expense): Other Nonoperating Income (Expense) Other income, net Interest and Debt Expense Interest expense Nonoperating Income (Expense) Total other income Net Income (Loss) Attributable to Parent Net loss Net loss Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other comprehensive loss: Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax Unrealized gain (loss) on investments Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive loss Earnings Per Share, Basic and Diluted Net loss per share applicable to common stockholders - basic and diluted (in dollars per share) Net loss per share - basic and diluted (in dollars per share) Weighted Average Number of Shares Outstanding, Basic and Diluted Weighted-average number of common shares used in net loss per share applicable to common stockholders — basic and diluted Statement of Cash Flows [Abstract] Net Cash Provided by (Used in) Operating Activities [Abstract] Operating activities Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net loss 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 Amortization of Debt Issuance Costs Noncash interest expense Share-based Compensation Stock-based compensation The cash inflow from the accretion of premiums and discounts on investments. Accretion Of Premiums And Discounts On Investments Accretion of premiums and discounts on investments Increase (Decrease) in Operating Capital [Abstract] Changes in assets and liabilities: The increase (decrease) during the reporting period of the amount of customer assets. Increase (Decrease) in Customer Assets Unbilled accounts receivable Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other current assets Increase (Decrease) in Other Noncurrent Assets Other assets Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accrued Liabilities Accrued expenses Increase (Decrease) in Contract with Customer, Liability Deferred revenue Changes in deferred revenue Amount of increase (decrease) in deferred rent. Increase Decrease In Deferred Rent Deferred rent Net Cash Provided by (Used in) Operating Activities Net cash used in operating activities Net Cash Provided by (Used in) Investing Activities [Abstract] Investing activities Payments to Acquire Property, Plant, and Equipment Purchases of property and equipment Payments to Acquire Available-for-sale Securities, Debt Purchases of investments Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities Maturities of investments Net Cash Provided by (Used in) Investing Activities Net cash used in by investing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Financing activities Repayments of Bank Debt Principal payments on loan payable Repayments of Long-term Capital Lease Obligations Principal payments on capital lease obligations Payments of Stock Issuance Costs Payment of offering costs Proceeds from Issuance Initial Public Offering Proceeds from public offering of common stock, net of commissions and underwriting discounts Proceeds from Issuance of Common Stock Proceeds from issuance of common stock, net of repurchases Proceeds from issuance of common stock Net Cash Provided by (Used in) Financing Activities Net cash provided by financing activities Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Net (decrease) increase in cash, cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents, and restricted cash at end of period Cash, cash equivalents, and restricted cash at beginning of period Total cash, cash equivalents, and restricted cash shown in condensed consolidated statements of cash flows Supplemental Cash Flow Information [Abstract] Supplemental cash flow information Represents the future cash outflow to pay stock issuance costs that have occurred in a noncash or partial noncash transaction. Stock Issuance Costs Incurred but Not yet Paid Noncash Or Partial Noncash Transaction Public offering costs incurred but unpaid at period end Capital Expenditures Incurred but Not yet Paid Property and equipment purchases unpaid at period end Interest Paid, Net Cash paid for interest Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Reconciliation of cash, cash equivalents, and restricted cash Restricted Cash and Cash Equivalents Restricted cash Organization, Consolidation and Presentation of Financial Statements [Abstract] Disclosure Text Block [Abstract] Disclosure Text Block Nature of Operations [Text Block] Nature of Business Accounting Policies [Abstract] Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies and Recent Accounting Pronouncements Investments and Cash [Abstract] Cash, Cash Equivalents, and Marketable Securities [Text Block] Cash Equivalents and Investments Fair Value Disclosures [Abstract] Fair Value Disclosures [Text Block] Fair Value of Financial Instruments Restricted Cash and Investments [Abstract] Restricted Assets Disclosure [Text Block] Restricted Cash Collaborative Arrangement Disclosure [Abstract] Collaborative Arrangement Disclosure [Abstract] Collaborative Arrangement Disclosure [Text Block] Collaborations Debt Disclosure [Abstract] Long-term Debt [Text Block] Term Loan Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock Awards Earnings Per Share [Abstract] Earnings Per Share [Text Block] Net Loss per Share Commitments and Contingencies Disclosure [Abstract] Commitments Disclosure [Text Block] Commitments Policy Text Block [Abstract] Policy Text Blocks Basis of Accounting, Policy [Policy Text Block] Basis of Presentation Use of Estimates, Policy [Policy Text Block] Use of Estimates Disclosure of significant accounting policies. Significant Accounting Policy [Policy Text Block] Significant Accounting Policies Revenue from Contract with Customer [Policy Text Block] Revenue recognition New Accounting Pronouncements, Policy [Policy Text Block] Recent Accounting Pronouncements Revenue, Initial Application Period Cumulative Effect Transition [Table] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Schedule of financial statement impact of the cumulative adjustment Table Text Block [Abstract] Table Text Blocks Cash, Cash Equivalents and Investments [Table Text Block] Schedule of cash equivalents and investments, available-for-sale Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Schedule of financial instruments measured at fair value Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of stock option activity Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Assumptions used in estimating fair value of stock options on grant date Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Summary of stock-based compensation expense recognized in statements of operations Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of common stock equivalents excluded from calculation of diluted net loss per share applicable to common stockholders Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Sale of Stock [Axis] Sale Of Stock Name Of Transaction [Domain] Sale of Stock [Domain] I P O [Member] IPO Follow-on public offering. Follow On Offering [Member] Follow-on Offering Subsidiary, Sale of Stock [Line Items] Nature of Business Stock Issued During Period, Shares, New Issues Stock sold (in shares) Share Price Share price (in dollars per share) Cash, Cash Equivalents, and Short-term Investments [Abstract] Cash, cash equivalents and investments Cash, Cash Equivalents, and Short-term Investments Cash, cash equivalents and investments Revenue, Initial Application Period Cumulative Effect Transition [Abstract] Summary of Significant Accounting Policies and Recent Accounting Pronouncements Contract with Customer, Liability Deferred revenue Investments [Abstract] Cash Equivalents and Investments Cash Equivalents, at Carrying Value Cash equivalents, Amortized Cost Cash and Cash Equivalents, Fair Value Disclosure Cash equivalents Debt Securities, Available-for-sale, Maturity, Average Maturity Debt Securities, Available-for-sale, Maturity, Average Maturity Average Maturity Available-for-sale Debt Securities, Amortized Cost Basis Available-for-sale, Amortized Cost Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax Available-for-sale, Unrealized Gain Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax Available-for-sale, Unrealized Losses Available-for-sale Securities, Debt Securities Investments, available-for-sale Debt Securities, Available-for-sale, Type [Extensible List] Investments, available-for-sale, type Represents the cost of cash equivalents and cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. Cash Equivalent and Available For Sale Debt Securities Amortized Cost Basis Total, Amortized Cost Cash Equivalents and Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Cash Equivalents and Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Total, Unrealized Gain Cash Equivalents and Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Cash Equivalents and Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Total, Unrealized Losses Represents the fair value of cash equivalents and amount of debt securities categorized neither as held-to-maturity nor trading. Cash Equivalents and Available-for-sale Securities, Debt Securities, Fair Value Total, Fair Value Debt Securities, Available-for-sale, Realized Gain (Loss) [Abstract] Realized gain (loss) on sales of investments Debt Securities, Available-for-sale, Realized Gain (Loss) Realized gain (loss) on sales of investments Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract] Adjustment for other than temporary fair value decline Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale Adjustment for other than temporary fair value decline Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions [Abstract] Unrealized loss position, number of positions Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions Number of held securities in an unrealized loss position Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract] Unrealized loss position, aggregate fair value Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Unrealized loss position for less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Unrealized loss position for more than 12 months Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Fair Value Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value Measurements Recurring [Member] Recurring Fair Value, Hierarchy [Axis] Fair Value Measurements Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value Inputs Level1 [Member] Active Markets (Level 1) Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Net Asset (Liability) [Abstract] Fair Value of Financial Instruments Assets, Fair Value Disclosure Total Restrictions on Cash and Cash Equivalents [Table] Restricted Cash and Cash Equivalents [Axis] Restricted Cash And Cash Equivalents Cash And Cash Equivalents [Member] Cash and Cash Equivalents [Domain] Restricted by bank. Restricted By Bank [Member] Restricted by bank Restricted Cash and Cash Equivalents Items [Line Items] Restricted Cash and Investments, Noncurrent [Abstract] Restricted Cash Schedule of Collaborative Arrangements and Non-collaborative Arrangement Transactions [Table] Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Collaborations Collaborative Arrangement Eligible Milestone Payments. Collaborative Arrangement Eligible Milestone Payments Eligible milestone payments Licensed Product Term From First Commercial Sale. Licensed Product Term From First Commercial Sale Licensed product term from first commercial sale The number of material components. Number of Materials Components Number of materials components Reversal of cumulative milestone revenue not occur for developmental milestone. Reversal of Cumulative Milestone Revenue Not Occur for Developmental Milestone Reversal of cumulative milestone revenue not occur for developmental milestone Cumulative catch-up of revenue for developmental milestone recognized. Cumulative Catch-Up of Revenue for Developmental Milestone Recognized Cumulative catch-up of revenue for developmental milestone recognized Remaining amount to be recognized over research and development period. Remaining Amount to be Recognized Over Research and Development Period Remaining amount to be recognized over research and development period Represents the number of collaboration programs. Number Of Collaboration Programs Number of potential collaboration programs Represents the number of collaboration programs with agreed upon targets, which are expected to begin in current fiscal year. Number Of Collaboration Programs With Selected Targets Number of collaboration programs with agreed upon targets Represents the number of license option rights to obtain an exclusive license to exploit products derived from the collaboration programs. Number Of License Option Rights Number of option rights to obtain exclusive license Represents the number of collaboration programs with exclusive commercialization rights for licensed products. Number Of Collaboration Programs With Exclusive Commercialization Rights Number of collaboration programs with exclusive commercialization rights for licensed products The number of material promises. Number of Material Promises Number of material promises Number of performance obligation identified by entity. Number of Performance Obligation Number of performance obligation Represents the number of collaboration programs in which the entity will retain commercialization rights in the United States for the licensed products, and counterparty will receive commercialization rights outside of the United States for the licensed products. Number Of Collaboration Programs With Specified Commercialization Rights Number of collaboration programs with specified commercial rights for each party Nonrefundable Upfront and Milestone Payment Received Nonrefundable Upfront and Milestone Payment Received Non-refundable upfront and milestone payment received Non-refundable upfront payment received by the reporting entity from the collaborative partner. Nonrefundable Upfront Payment Received Non-refundable upfront payment received Nonrefundable Milestone Payment Received Nonrefundable Milestone Payment Received Non-refundable milestone payment received Cumulative Nonrefundable Milestone Payment Received Cumulative Nonrefundable Milestone Payment Received Cumulative Non-refundable milestone payments received Represents the aggregate amount of eligible contingent option fees and milestone payments related to specified research, pre-clinical, clinical, regulatory and sales-based milestones. Collaborative Arrangement Eligible Contingent Option Fees And Milestone Payments Total eligible contingent option fees and milestone payments Represents the amount of option fees and milestone payments for research, pre-clinical and clinical development events prior to licensing across all five potential collaboration programs, including contingent milestone payments for initiation of each of the collaboration programs for which the parties will work together to select targets (pre-option exercise milestones). Collaborative Arrangement Eligible Option Fees And Milestone Payments Prior To Licensing Across All Programs Eligible option fees and milestones prior to licensing for all potential collaboration programs The period of time for which written notice is required to be received from the collaborative partner prior to termination of the collaborative agreement. Collaborative Arrangement Period Of Prior Notice To Terminate Agreement Written termination notice period Initial Cash Payment Per Collaboration Agreement. Initial Cash Payment Per Collaboration Agreement Initial cash payment Related to research and development costs incurred under the research plan, the percentage of funding for which the collaborative partner to the reporting entity is responsible per the collaborative agreement. Research And Development Costs Incurred Under Research Plan Collaborative Partner Funding Percentage Per Agreement Collaborative partner's funding responsibility of research and development costs incurred under the research plan (as a percent) The number of deliverables determined per the collaborative agreement. Collaborative Agreement Number Of Deliverables Number of deliverables Represents the cash inflow from achieved milestone payment received, which will be recognized as revenue over the period of performance. Achieved Milestone Payment Received To Be Recognized Over Performance Period Achieved milestone payment received which will be recognized over period of performance Represents the reimbursable research and development costs recognized during the period. Reimbursable Research And Development Costs Recognized Reimbursable research and development costs recognized Non-substantive milestone payment previously received. Non-substantive Milestone Payment Previously Received Non-substantive milestone payment previously Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Research and development services, performance period Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Longterm Debt Type [Domain] Long-term Debt, Type [Domain] Secured Debt [Member] Secured Debt Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Prime Rate [Member] Prime Rate Debt Instrument [Line Items] Debt Instruments [Abstract] Term Loan Debt Instrument, Face Amount Face amount Represents the number of tranches or structured financing of the debt agreement. Debt Instrument Number Of Tranches Number of tranches Debt Instrument, Basis Spread on Variable Rate Fixed rate based on percentage points added to base rate (as a percent) Proceeds from Bank Debt Proceeds from term loan The fee payable, expressed as a percent, on total loan advances on a debt instrument. Debt Instrument, Fee Payable on Total Loan Advances, Percentage Percentage fee payable on total loan advances at end of loan (as a percent) The prepayment fee, expressed as a percent, on outstanding principal at the time prepayment on a debt instrument, low end of range. Debt Instrument, Prepayment Fee, Percentage, Low End of Range Percentage fee payable on outstanding principal in event of prepayment of loan advances, low end of range (as a percent) The prepayment fee, expressed as a percent, on outstanding principal at the time prepayment on a debt instrument, high end of range. Debt Instrument, Prepayment Fee, Percentage, High End of Range Percentage fee payable on outstanding principal in event of prepayment of loan advances, high end of range (as a percent) Long-term Debt, Fiscal Year Maturity [Abstract] Future minimum payments Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year Future minimum payments for remainder of year Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Represents the stock option and incentive plan approved in 2015. Stock Option And Incentive Plan2015 [Member] 2015 Stock Option and Incentive Plan Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract] Stock Awards Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Initial shares of common stock authorized for issuance of stock awards The percentage of additional shares authorized for issuance under an established share-based compensation plan. Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Additional Shares Authorized Increase in number of shares available for grant (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized Increase in number of shares available for grant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Number of shares available for grant Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Award vesting period Period which an new employee's cliff right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format. Share-based Compensation Arrangement by Share-based Payment Award, Award Cliff Vesting Period for New Employees Cliff vesting period for new employees Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Award expiration period Award Type [Axis] Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain] Equity Award [Domain] Restricted Stock [Member] Restricted Stock Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Stock Awards Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares Unvested stock options Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Total fair value of restricted stock that vested Employee Stock Option [Member] Employee Stock Options 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 end of period (in shares) Outstanding at beginning of period (in shares) 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, Exercises in Period Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Other Increases (Decreases) in Period Cancelled (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Weighted-Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Outstanding at end of period (in dollars per share) Outstanding at beginning of 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 Arrangements by Share-based Payment Award, Options, Other Share Increase (Decrease) in Period, Weighted Average Exercise Price Cancelled (in dollars per share) 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, Vested and Expected to Vest, Exercisable, Number Shares - Exercisable (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price Weighted-Average Exercise Price - Exercisable (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Remaining Contractual Life - Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term Remaining Contractual Life - Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate Intrinsic Value - Outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Aggregate Intrinsic Value - Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract] Assumptions used in estimating the fair value of stock options granted Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate Expected dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Expected term (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Weighted Average Volatility Rate Expected stock price volatility 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 of options granted Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Total intrinsic value of options exercised 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 Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Employee Service Share-based Compensation, Aggregate Disclosures [Abstract] Total stock based compensation expense Allocated Share-based Compensation Expense Total stock-based compensation expense Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized [Abstract] Stock Awards Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Total unrecognized compensation cost related to non-vested stock awards Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Weighted-average period over which unrecognized compensation cost will be recognized Represents employee stock purchase plan approved in 2015. Employee Stock Purchase Plan2015 [Member] 2015 Employee Stock Purchase Plan Common Stock, Capital Shares Reserved for Future Issuance Number of common shares reserved for future issuance Represents the annual cumulative increase for common stock issuance, as a percentage of the number of shares of common stock issued and outstanding. Annual Cumulative Increase Percentage of Number of Share of Common Stock Issued and Outstanding Annual increase for common stock for issuance (as a percent) Increase in aggregate number of common shares reserved for future issuance. Common Stock Increase Capital Shares Reserved for Future Issuance Increase of common shares reserved for future issuance Stock Issued During Period, Shares, Employee Stock Purchase Plans ESPP shares issued during period Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities Name [Domain] Antidilutive Securities, Name [Domain] Stock Option [Member] Stock options Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract] Antidilutive securities excluded from computation of earnings per share Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive securities excluded from computation of earnings per share Weighted Average Number of Shares Outstanding, Diluted [Abstract] Net Loss per Share Weighted Average Number of Shares Outstanding, Basic Weighted-average number of common shares used in net loss per share applicable to common stockholders - basic Weighted Average Number of Shares Outstanding, Diluted Weighted-average number of common shares used in net loss per share applicable to common stockholders - diluted Schedule of Operating Leased Assets [Table] Lease Arrangement, Type [Axis] Lease Arrangement Type [Domain] Lease Arrangement, Type [Domain] Represents information pertaining to corporate headquarters office and laboratory space in Cambridge, Massachusetts. Office And Laboratory Space In Cambridge Massachusetts [Member] Corporate Headquarters Lease Operating Leased Assets [Line Items] Leases, Operating [Abstract] Operating Leases Area of Real Estate Property Area leased (in square feet) Number of extensions to an operating lease. Operating Leases, Renewal Term, Extensions, Number Number of extensions Lessee, Operating Lease, Renewal Term Extension period of lease term Operating Leases, Future Minimum Payments Due Total commitment under the operating lease Lessee, Operating Lease, Term of Contract Lease term Represents the initial base annual rent for an operating lease. Operating Leases Base Annual Rent Initial Base annual rent, initial Represents the maximum base annual rent for an operating lease. Operating Leases, Base Annual Rent, Maximum Base annual rent, maximum Allowance granted to lessee and/or direct costs incurred by lessor used to prepare the leased premises for tenant's occupancy. Operating Leases, Allowance for Leasehold Improvements Allowance for leasehold improvements Security Deposit Security deposit included in restricted cash Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals Total commitment in sublease Lessee, Operating Lease, Term of Contract, Sublease Lessee, Operating Lease, Term of Contract, Sublease Sublease term The Amount of contractually required sublease revenue portion payable to land lord. Operating Leases, Sublease Rental Payable to Land Lord Sublease payable Operating leases, tenant improvement allowance. Operating Leases, Tenant Improvement Allowance Tenant improvement allowance Operating Leases, Rent Expense Rent expense Adjustments for New Accounting Pronouncements [Axis] Type Of Adoption [Member] Type of Adoption [Domain] Accounting Standards Update201409 [Member] Accounting Standards Update 2014-09 Over Allotment Option [Member] Underwriters' Option New Accounting Pronouncement [Member] Adjustments for New Accounting Pronouncement [Member] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Difference Between Revenue Guidance In Effect Before And After Topic606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 Calculated Under Revenue Guidance In Effect Before Topic606 [Member] Calculated under Revenue Guidance in Effect before Topic 606 Fair Value Inputs Level12 And3 [Member] Fair Value, Inputs, Level 1, 2 and 3 [Member] Office and Laboratory Space in Cambridge Massachusetts, 38 Sidney Street, and 45 Sidney Street [Member] Office And Laboratory Space In Cambridge Massachusetts38 Sidney Street And45 Sidney Street [Member] Cambridge Massachusetts, 38 Sidney Street and 45 Sidney Street Leases Type of Arrangement and Non-arrangement Transactions [Axis] Arrangements And Nonarrangement Transactions [Member] Arrangements and Non-arrangement Transactions [Domain] Collaborative Arrangement [Member] Collaboration C Stone Collaboration and License Agreement. C Stone Collaboration And License Agreement [Member] Cstone Agreement Represents the collaboration and license agreement with F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. (collectively, Roche) for discovery, development and commercialization of up to five small molecule therapeutics targeting kinases believed to be important in cancer immunotherapy, as single products or possibly in combination with other therapeutics. Roche Collaboration And License Arrangement [Member] Roche Agreement Represents the collaboration arrangement with Alexion Pharma Holding (Alexion) to research, develop and commercialize drug candidates for an undisclosed activated kinase target, which is the cause of a rare genetic disease. Alexion Collaborative Arrangement [Member] Alexion Counterparty Name [Axis] Repurchase Agreement Counterparty Name [Domain] Counterparty Name [Domain] C Stone. C Stone [Member] C Stone Represents information pertaining to F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. Roche [Member] Roche Research and Development Arrangement, Contract to Perform for Others, Type [Axis] Research And Development Arrangement Contract To Perform For Others Type [Domain] Research and Development Arrangement, Contract to Perform for Others, Type [Domain] License Agreement Terms [Member] License Agreement Terms [Member] Represents information pertaining to the agreement terms prior to exercise license right option under research and development arrangements. Prior To Exercise License Right Option [Member] Prior To Exercise License Right Option Represents information pertaining to the agreement terms of exercise of license option under research and development arrangements. Exercise Of License Right Option [Member] Exercise Of License Right Option Represents information pertaining to the agreement terms of exercise of license option, where product has not been commercially sold under research and development arrangements. Exercise Of License Option Product Not Commercially Sold [Member] Exercise Of License Option Product Not Commercially Sold Represents information pertaining to the agreement terms of exercise of license option, where product has been commercially sold under research and development arrangements. Exercise Of License Option Product Commercially Sold [Member] Exercise Of License Option Product Commercially Sold Information by categories of milestones. Milestone [Axis] Different categories of milestones. Milestone [Domain] Milestone [Domain] Development and Regulatory Milestones. Development And Regulatory Milestones [Member] Development and regulatory milestones Sales Based Milestones. Sales Based Milestones [Member] Sales-based milestones Debt Instrument [Axis] Debt Instrument Name [Domain] Debt Instrument, Name [Domain] 2013 Term Loan. Term Loan2013 [Member] 2013 Term Loan 2014 Term Loan. Term Loan2014 [Member] 2014 Term Loan Employee Stock [Member] Employee Stock Office and laboratory space located at 45 Sidney Street in Cambridge Massachusetts. Office And Laboratory Space In Cambridge Massachusetts45 Sidney Street [Member] Office and Laboratory Space in Cambridge Massachusetts, 45 Sidney Street