This concept does not have a custom type definition. Document and Entity Information [Abstract] Statement [Table] Statement 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 Condensed 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 Available-for-sale Securities, Debt Securities, Current Investments, available-for-sale Restricted Cash and Cash Equivalents, Current Restricted cash Represents the current amount of unbilled accounts receivable, including reimbursable research and development costs. Unbilled Receivables Including Reimbursable Costs Current Unbilled accounts receivable Unbilled accounts receivable for reimbursable research and development costs Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Assets, Current Total current assets Property, Plant and Equipment, Net Property and equipment, net Other Assets, Noncurrent Other assets Restricted Cash and Cash Equivalents, Noncurrent Restricted cash Restricted cash included in long-term 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 Deferred Compensation Share-based Arrangements, Liability, Current Restricted stock liability Deferred Revenue, Current Current portion of deferred revenue 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 Deferred Compensation Liability, Classified, Noncurrent Restricted stock liability, net of current portion Deferred Revenue, Noncurrent 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 Loans Payable to Bank, Noncurrent Term loan payable, net of current portion Other Liabilities, Noncurrent Other long term liabilities Commitments and Contingencies Commitments (Note 11) Stockholders' Equity Attributable to Parent [Abstract] Stockholders' deficit: 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; 27,276,990 and 27,196,053 shares issued at June 30, 2016 and December 31, 2015, respectively, and 27,227,415 and 27,065,558 shares outstanding at June 30, 2016 and December 31, 2015, respectively Additional Paid in Capital Additional paid-in capital Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income Retained Earnings (Accumulated Deficit) Accumulated deficit Stockholders' Equity Attributable to Parent Total stockholders' equity Liabilities and Equity Total liabilities and stockholders' equity Temporary Equity, Other Disclosures [Abstract] Temporary Equity Disclosures 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 Preferred Stock, Shares Issued Preferred stock, shares issued Preferred Stock, Shares Outstanding Preferred stock, shares outstanding 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 NIS dollars per share) Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common stock, shares issued Common Stock, Shares, Outstanding Condensed Consolidated Statements of Operations and Comprehensive Loss Revenues [Abstract] Revenues Revenues 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 (expense), net Interest and Debt Expense Interest expense Nonoperating Income (Expense) Total other income (expense) Net Income (Loss) Attributable to Parent Net loss Net loss Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax Unrealized gain on investments Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive loss Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Reconciliation of net loss applicable to common stockholders: Temporary Equity, Dividends, Adjustment Convertible preferred stock dividends Net Income (Loss) Available to Common Stockholders, Basic Net loss applicable to common stockholders Income (Loss) from Continuing Operations, Per Basic and Diluted Share Net loss per share applicable to common stockholders - basic and diluted 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 Condensed Consolidated Statements of Cash Flows Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] 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 Amortization of Financing Costs Noncash interest expense Fair Value Adjustment of Warrants Change in fair value of warrant liability 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: Increase (Decrease) in Unbilled Receivables 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 Deferred Revenue Deferred revenue Increase (Decrease) in Other Deferred Liability Deferred rent Net Cash Provided by (Used in) Operating Activities, Continuing Operations Net cash provided by (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 Increase (Decrease) in Restricted Cash Restricted cash 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, Continuing Operations Net cash used in investing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Financing activities Repayments of Bank Debt Principal payments on loan payable Proceeds from Issuance Initial Public Offering Proceeds from issuance of IPO shares Proceeds from IPO, net of commissions and underwriting discounts Payments of Stock Issuance Costs Payment of offering costs Proceeds from Issuance of Common Stock Proceeds from issuance of common stock, net of repurchases 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 Net (decrease) increase in cash and cash equivalents Supplemental Cash Flow Information [Abstract] Supplemental cash flow information Interest Paid, Net Cash paid for interest Capital Expenditures Incurred but Not yet Paid Property and equipment purchases incurred but unpaid at period end Conversion of Stock, Amount Converted Conversion of convertible preferred stock into common stock The value of warrant liability that was reclassified to additional paid-in-capital. Reclassification of Warrant Liability to Additional Paid In Capital Reclassification of warrant liability to additional paid-in-capital 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 Nature of Business Nature of Operations [Text Block] Nature of Business Summary of Significant Accounting Policies and Recent Accounting Pronouncements Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] Summary of Significant Accounting Policies and Recent Accounting Pronouncements Cash Equivalents and Investments Cash, Cash Equivalents, and Marketable Securities [Text Block] Cash Equivalents and Investments Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Fair Value of Financial Instruments Restricted Cash Restricted Assets Disclosure [Text Block] Restricted Cash No definitions available. Collaborations Collaborative Arrangement Disclosure [Text Block] Collaborations Term Loan Long-term Debt [Text Block] Term Loan Warrants The entire disclosure for warrants. Warrants Disclosure [Text Block] Warrants Stock Awards Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock Awards Net Loss per Share Earnings Per Share [Text Block] Net Loss per Share Commitments. Commitments Disclosure [Text Block] Commitments Basis of Accounting, Policy [Policy Text Block] Basis of Presentation Use of Estimates, Policy [Policy Text Block] Use of Estimates Marketable Securities, Available-for-sale Securities, Policy [Policy Text Block] Available-for-sale Investments New Accounting Pronouncements, Policy [Policy Text Block] Recent Accounting Pronouncements 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 Nonvested Restricted Stock Shares Activity [Table Text Block] Summary of unvested restricted stock Schedule of 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 Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common Stock Subsidiary, Sale of Stock [Line Items] Initial Public Offering Stock Issued During Period, Shares, New Issues Stock sold (in shares) Number of new stock issued during the period to underwriters pursuant to the full exercise of an option to purchase additional shares granted in connection with the offering. Stock Issued During Period Shares New Issues Underwriters Shares issued to underwriters in IPO Share Price Share price (in dollars per share) Conversion of Stock [Table] Stock Conversion Description [Axis] Conversion Of Stock Name [Domain] Conversion of Stock, Name [Domain] Conversion of Stock [Line Items] Stock Split and Conversion of stock Stockholders' Equity Note, Stock Split, Conversion Ratio Reverse stock split ratio Conversion of Stock, Shares Issued Shares issued upon stock conversion (in shares) Class of Warrant or Right, Number of Securities Called by Warrants or Rights Number of shares that can be purchased by the warrants issued Investment Holdings [Table] Cash and Cash Equivalents [Axis] Restricted Cash And Cash Equivalents Cash And Cash Equivalents [Member] Cash and Cash Equivalents [Domain] Money Market Funds [Member] Money market fund Investment Holdings [Line Items] Cash Equivalents and Investments Represents the average maturity of available-for-sale security. Average Maturity Of Available For Sale Security Average Maturity Cash Equivalents, at Carrying Value Cash equivalents, Amortized Cost Cash and Cash Equivalents, Fair Value Disclosure Cash equivalents Cash equivalents, Fair Value Available-for-sale Debt Securities, Amortized Cost Basis Available-for-sale, Amortized Cost 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 Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax Available-for-sale, Unrealized Gain Available-for-sale Securities, Debt Securities Available-for-sale, Fair Value 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 Available-for-sale Securities, Gross Realized Gain (Loss) Realized gain (loss) on sales of investments Other than Temporary Impairment Losses, Investments, Available-for-sale Securities Adjustment for other than temporary FV decline 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 of Financial Instruments Available-for-sale Securities Investments, available-for-sale Assets, Fair Value Disclosure Total Schedule of Restricted Cash and Cash Equivalents [Table] Restricted Cash and Cash Equivalents [Axis] Restricted by bank Restricted By Bank [Member] Restricted by bank Restricted Cash and Cash Equivalents Items [Line Items] Restricted Cash Restricted Cash and Cash Equivalents Restricted cash, current and noncurrent 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] Collaborative Arrangement [Member] Collaboration 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 Information by categories of milestones. Milestone [Axis] Different categories of milestones. Milestone [Domain] Milestone [Domain] Pre-clinical milestone for the first licensed product. Preclinical Milestone First Licensed Product [Member] Pre-clinical milestone for first licensed product Development milestone for the first licensed product. Development Milestone First Licensed Product [Member] Development milestone for first licensed product Development milestone for the second licensed product. Development Milestone Second Licensed Product [Member] Development milestone for second licensed product Commercial milestone. Commercial Milestone [Member] Commercial milestone Range [Axis] Range [Member] Range [Domain] Maximum [Member] Maximum Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Collaboration Agreement 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) Non-refundable upfront payment received by the reporting entity from the collaborative partner. Nonrefundable Upfront Payment Received Non-refundable upfront payment received Represents the amount receivable by the reporting entity from the collaborative partner upon achievement of certain milestones. Milestone Achievement Payments Receivable Payment receivable upon achievement of milestone The royalty term from first commercial sale, option 1. Licensed Product Royalty Term From First Commercial Sale Option1 Royalty term from first commercial sale, option 1 The royalty term from first commercial sale, option 2. Licensed Product Royalty Term From First Commercial Sale Option2 Royalty term from first commercial sale, option 2 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 The number of deliverables determined per the collaborative agreement. Collaborative Agreement Number Of Deliverables Number of deliverables Represents the amount of refund provisions with in the collaboration agreement. Refund Provisions Within Collaboration Agreement Refund provisions 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 Revenue Recognition, Milestone Method, Revenue Recognized Revenue recognized from milestone Represents the amount of reimbursable research and development costs received during the period. Reimbursable Research And Development Costs Reimbursable research and development costs 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 Number of collaboration programs that began in the first half of the fiscal year. Number Of Collaboration Programs Started In First Half Of Year Number of collaboration programs that began during first half of 2016 Represents the number of collaboration programs agreed to select targets. Number Of Additional Collaboration Programs To Select Targets Number of collaboration programs to select 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 collaborations programs with exclusive commercialization rights for licensed products 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 program with specified commercial rights for each party 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 Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument Name [Domain] Debt Instrument, Name [Domain] Loan and security agreement. Loan And Security Agreement [Member] Loan and Security Agreement Long-term Debt, Type [Axis] Longterm Debt Type [Domain] Long-term Debt, Type [Domain] Secured Debt [Member] 2013 Term Loan 2014 term loan collateralized debt obligations backed by, for example, but not limited to, pledge, mortgage or other lien on the entity's assets. Term Loan2014 [Member] 2014 Term Loan Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Prime Rate [Member] Prime Rate Debt Instrument [Line Items] Term Loan Line of Credit Facility, Maximum Borrowing Capacity Maximum borrowing capacity 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 Proceeds from Bank Debt Proceeds from bank debt Increase in the maximum borrowing capacity under the credit facility. Line Of Credit Facility Increase In Maximum Borrowing Capacity Increase in maximum borrowing capacity Percentage fee payable on total loan advances at end of loan. Percentage Fee Payable On Total Loan Advances At End Of Loan Percentage fee payable on total loan advances at end of loan Percentage fee payable on outstanding principal in event of prepayment of loan advances, option 1. Percentage Fee Payable On Outstanding Principal In Event Of Prepayment Of Loan Advances Option1 Percentage fee payable on outstanding principal in event of prepayment of loan advances, option 1 Percentage fee payable on outstanding principal in event of prepayment of loan advances, option 2. Percentage Fee Payable On Outstanding Principal In Event Of Prepayment Of Loan Advances Option2 Percentage fee payable on outstanding principal in event of prepayment of loan advances, option 2. Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year Future minimum payments for remainder of year Class of Warrant or Right [Table] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other Expense [Member] Other expense Class of Warrant or Right [Axis] Class Of Warrant Or Right [Domain] Class of Warrant or Right [Domain] Represents information pertaining to both Series A warrants and Series B warrants. Series And Series B Warrants [Member] Series A and Series B Warrants Represents information pertaining to series A warrants. Seriesa Warrants [Member] Series A Warrants Represents information pertaining to series B warrants. Series B Warrants [Member] Series B Warrants Class Of Warrants Or Right [Line Items] Warrants Class of Warrant or Right, Exercise Price of Warrants or Rights Exercise price of warrants issued (in dollars per share) Represents the term of warrants. Warrant Term Warrants life The number of common shares that became exercisable from warrants. Number Of Common Shares Exercisable From Warrants Number of common shares that became exercisable from warrants Stock Issued During Period, Shares, Conversion of Convertible Securities Stock issued upon exercise of warrants The number of warrants for common stock that were cancelled as payment for the aggregate exercise price of the warrant. Number Of Warrants For Common Stock Cancelled Number of warrants cancelled Interest Expense Interest expense 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] 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, Nonvested, Number of Shares [Roll Forward] Unvested restricted stock rollforward Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Unvested at beginning of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Vested ( in shares) The number of equity-based payment instruments, excluding stock (or unit) options, that were repurchased during the reporting period. Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Repurchased In Period Repurchased (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number Unvested at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Nonvested stock awards, 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 end of period (in dollars per share) Unvested at beginning or 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) The weighted average fair value as of grant date of awards repurchased pertaining to an equity-based award plan other than a stock (or unit) option plan. Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Repurchased In Period Weighted Average Grant Date Fair Value Repurchased (in dollars per share) 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] Stock option rollforward 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 Canceled ( in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number Exercisable at end of 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 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, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price Exercisable at end of 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 Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Other disclosures 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 at end of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Remaining contractual life, vested and expected to vest at end of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate intrinsic value, outstanding at end of period Aggregate intrinsic value, outstanding at beginning of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Aggregate intrinsic value, exercisable at end of period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Aggregate intrinsic value, vested and expected to vest at end of period The forfeiture rate used to determine the unvested options that are expected to vest. Share Based Compensation Arrangement By Share Based Payment Award Forfeiture Rate Forfeiture rate (as a percent) 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 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] 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] Stock-based compensation Allocated Share-based Compensation Expense 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 of awards 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] 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 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] Operating Leases Represents the additional extension period on prior lease that expired. Extension Period Expired On Prior Lease Prior lease extension period Area of Real Estate Property Area leased (in square feet) Lessee Leasing Arrangements, Operating Leases, Renewal Term Extension period of lease term Operating Leases, Future Minimum Payments Due Total commitment under the operating lease Lessee Leasing Arrangements, Operating Leases, 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, Rent Expense Rent expense 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] US Treasury obligations Asset Class [Axis] Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain] Asset Class [Domain] Counterparty Name [Axis] Repurchase Agreement Counterparty Name [Domain] Counterparty Name [Domain] 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