Entity Central Index Key Document and entity information. Document And Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Well Known Seasoned Issuer Entity Current Reporting Status Entity Current Reporting Status Entity Voluntary Filers Entity Voluntary Filers Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Entity Public Float Entity Public Float Lease incentive payable noncurrent. Statement Of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Current portion of accounts receivable Accounts Receivable Net Current Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Long-term assets: Assets Noncurrent [Abstract] Accounts receivable, net of current portion Accounts Receivable Net Noncurrent Property and equipment, net Property Plant And Equipment Net Restricted cash Restricted Cash And Cash Equivalents Noncurrent Other assets Other Assets Total long-term assets Assets Noncurrent Total assets Assets Liabilities, Series A preferred shares and shareholders’ equity Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable Accounts Payable Current Accrued expenses and other current liabilities Accrued Liabilities And Other Liabilities Current portion of capital lease obligation Capital Lease Obligations Current Current portion of deferred rent Deferred Rent Credit Current Current portion of deferred revenue Contract With Customer Liability Current Current portion of lease incentive obligation Lease Incentive Payable Current Total current liabilities Liabilities Current Long-term liabilities: Liabilities Noncurrent [Abstract] Deferred rent, net of current portion Deferred Rent Credit Noncurrent Deferred revenue, net of current portion Contract With Customer Liability Noncurrent Lease incentive obligation, net of current portion Lease Incentive Payable Noncurrent Other liabilities Other Liabilities Noncurrent Total long-term liabilities Liabilities Noncurrent Total liabilities Liabilities Series A preferred shares, no par value; 3,901,348 shares issued and outstanding at December 31, 2018 and 2017 Temporary Equity Carrying Amount Attributable To Parent Shareholders’ equity: Stockholders Equity [Abstract] Ordinary shares, no par value; 29,472,197 and 27,829,079 shares issued and outstanding at December 31, 2018 and 2017, respectively Common Stock Value Additional paid-in capital Additional Paid In Capital Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income Loss Net Of Tax Accumulated deficit Retained Earnings Accumulated Deficit Total shareholders’ equity Stockholders Equity Total liabilities, Series A preferred shares and shareholders’ equity Liabilities And Stockholders Equity Series A preferred stock, par value Temporary Equity Par Or Stated Value Per Share Series A preferred stock, shares issued Temporary Equity Shares Issued Series A preferred stock, shares outstanding Temporary Equity Shares Outstanding Common stock, par value Common Stock No Par Value Common stock, shares issued Common Stock Shares Issued Common stock, shares outstanding Common Stock Shares Outstanding Income Statement [Abstract] Revenue Revenue From Contract With Customer Excluding Assessed Tax Operating expenses: Operating Expenses [Abstract] Research and development Research And Development Expense General and administrative General And Administrative Expense Total operating expenses Operating Expenses Loss from operations Operating Income Loss Other income (expense), net: Nonoperating Income Expense [Abstract] Dividend income Investment Income Dividend Interest income (expense), net Interest Income Expense Nonoperating Net Other income (expense), net Other Nonoperating Income Expense Other income (expense), net Nonoperating Income Expense Loss before income taxes Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest Income tax benefit (provision) Income Tax Expense Benefit Net loss Net Income Loss Net loss per share attributable to ordinary shareholders—basic and diluted Earnings Per Share Basic And Diluted Weighted-average ordinary shares used in computing net loss per share attributable to ordinary shareholders—basic and diluted Weighted Average Number Of Share Outstanding Basic And Diluted Other comprehensive income (loss): Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract] Net loss Foreign currency translation Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax Comprehensive loss Comprehensive Income Net Of Tax Stock issued during period shares restricted stock award vested. Statement Of Stockholders Equity [Abstract] Statement [Table] Statement [Table] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Ordinary Shares [Member] Common Stock [Member] Additional Paid-In-Capital [Member] Additional Paid In Capital [Member] Accumulated Other Comprehensive Income (Loss) [Member] Accumulated Other Comprehensive Income [Member] Accumulated Deficit [Member] Retained Earnings [Member] Class of Stock Statement Class Of Stock [Axis] Class of Stock Class Of Stock [Domain] Series A Preferred Shares [Member] Series A Preferred Stock [Member] Statement [Line Items] Statement [Line Items] Beginning balance Beginning balance, shares Shares Outstanding Temporary equity, Beginning balance Temporary equity, Beginning balance, shares Issuance of ordinary shares, net of offering costs Stock Issued During Period Value New Issues Issuance of ordinary shares, net of offering costs, shares Stock Issued During Period Shares New Issues Share-based compensation Stock Issued During Period Value Share Based Compensation Gross Share-based compensation, shares Stock Issued During Period Shares Share Based Compensation Gross Vesting of RSUs, shares Stock Issued During Period Shares Restricted Stock Award Vested Option exercises Stock Issued During Period Value Stock Options Exercised Option exercises, shares Stock Issued During Period Shares Stock Options Exercised Impact of adoption of ASU 2016-16 Cumulative Effect On Retained Earnings Net Of Tax1 Other comprehensive income (loss) Other Comprehensive Income Loss Net Of Tax Ending balance Ending balance, shares Temporary equity, Ending balance Temporary equity, Ending balance, shares Issuance costs Payments Of Stock Issuance Costs Amortization of lease incentive obligation. Statement Of Cash Flows [Abstract] Cash flows from operating activities Net Cash Provided By Used In Operating Activities [Abstract] Net loss Profit Loss Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Amortization of lease incentive obligation Amortization Of Lease Incentive Obligation Depreciation of property and equipment Depreciation Share-based compensation expense Allocated Share Based Compensation Expense Net (gain) loss on disposal of property and equipment Gain Loss On Sale Of Property Plant Equipment Deferred rent Straight Line Rent Adjustments Deferred income taxes Deferred Income Taxes And Tax Credits Tax benefit related to share-based compensation Excess Tax Benefit From Share Based Compensation Operating Activities Changes in operating assets and liabilities: Increase Decrease In Operating Capital [Abstract] Accounts receivable Increase Decrease In Accounts Receivable Prepaid expenses and other current assets Increase Decrease In Prepaid Deferred Expense And Other Assets Other assets Increase Decrease In Other Operating Assets Accounts payable Increase Decrease In Accounts Payable Accrued expenses and other current liabilities Increase Decrease In Accounts Payable And Accrued Liabilities Deferred revenue Increase Decrease In Contract With Customer Liability Other non-current liabilities Increase Decrease In Other Noncurrent Liabilities Net cash used in operating activities Net Cash Provided By Used In Operating Activities Cash flows from investing activities Net Cash Provided By Used In Investing Activities [Abstract] Proceeds from the sale of property and equipment Proceeds From Sale Of Property Plant And Equipment Purchases of property and equipment, net of tenant improvement allowances Payments To Acquire Property Plant And Equipment Net cash used in investing activities Net Cash Provided By Used In Investing Activities Cash flows from financing activities Net Cash Provided By Used In Financing Activities [Abstract] Costs associated with initial public offering Payments For Repurchase Of Initial Public Offering Proceeds from issuance of ordinary shares, net of offering costs Proceeds From Issuance Of Common Stock Payments on capital lease obligation Repayments Of Long Term Capital Lease Obligations Proceeds from the exercise of share options Proceeds From Stock Options Exercised Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Effect of foreign exchange rates on cash Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations Net increase (decrease) in cash, cash equivalents and restricted cash Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect Cash, cash equivalents and restricted cash, beginning of period Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations Cash, cash equivalents and restricted cash, end of period Organization Consolidation And Presentation Of Financial Statements [Abstract] The Company Organization Consolidation And Presentation Of Financial Statements Disclosure [Text Block] Accounting Policies [Abstract] Significant Accounting Policies Significant Accounting Policies [Text Block] Property Plant And Equipment [Abstract] Property and Equipment, Net Property Plant And Equipment Disclosure [Text Block] Payables And Accruals [Abstract] Accrued Expenses and Other Current Liabilities Accounts Payable Accrued Liabilities And Other Liabilities Disclosure Current [Text Block] Collaboration Agreements Collaborative Arrangement Disclosure [Text Block] Equity [Abstract] Share Capital Stockholders Equity Note Disclosure [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Share-Based Compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Commitments And Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments And Contingencies Disclosure [Text Block] Earnings Per Share [Abstract] Net Loss Per Ordinary Share Earnings Per Share [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Postemployment Benefits [Abstract] Employee Benefit Plans Compensation And Employee Benefit Plans [Text Block] Related Party Transactions [Abstract] Related Parties Related Party Transactions Disclosure [Text Block] Quarterly Financial Information Disclosure [Abstract] Selected Quarterly Financial Information (Unaudited) Quarterly Financial Information [Text Block] Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Cash Equivalents Cash And Cash Equivalents Policy [Text Block] Principles of Consolidation Consolidation Policy [Text Block] Use of Estimates Use Of Estimates Segment Data Segment Reporting Policy Policy [Text Block] Foreign Currency Translation Foreign Currency Transactions And Translations Policy [Text Block] Fair Value of Financial Instruments Fair Value Of Financial Instruments Policy Concentration of Credit Risk Concentration Risk Credit Risk Restricted Cash Cash And Cash Equivalents Restricted Cash And Cash Equivalents Policy Property and Equipment Property Plant And Equipment Policy [Text Block] Impairment of Long-Lived Assets Impairment Or Disposal Of Long Lived Assets Including Intangible Assets Policy Policy [Text Block] Revenue Recognition Revenue From Contract With Customer Policy [Text Block] Research and Development Expenses Research And Development Expense Policy Refundable tax credits. Refundable Tax Credits Refundable Tax Credits Policy [Text Block] Net Loss per Share Earnings Per Share Policy [Text Block] Revenue from contract with customer license agreements and patent costs. License Agreements and Patent Costs Revenue From Contract With Customer License Agreements And Patent Costs Policy [Text Block] Share-Based Compensation Share Based Compensation Option And Incentive Plans Policy Income Taxes Income Tax Policy [Text Block] Recently Issued Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Property Plant And Equipment Estimated Useful Lives Table [Text Block] Adjustments for New Accounting Pronouncements Adjustments For New Accounting Pronouncements [Axis] Type of Adoption Type Of Adoption [Member] ASC 606 [Member] Accounting Standards Update201409 [Member] Schedule of Estimated Useful Life of Assets Property Plant And Equipment Estimated Useful Lives Table [Text Block] Summary of Result of Adopting ASC 606 on Financial Statement Schedule Of Prospective Adoption Of New Accounting Pronouncements Table [Text Block] Schedule of Property and Equipment, Net Property Plant And Equipment [Text Block] Summary of Accrued Expenses and Other Current Liabilities Schedule Of Accrued Liabilities Table [Text Block] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Award Type Award Type [Axis] Equity Award Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain] Employee Stock Option [Member] Employee Stock Option [Member] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Summary of Share Option Activity Schedule Of Share Based Compensation Stock Options Activity Table [Text Block] Summary of Fair Value of Share Options Granted Schedule Of Share Based Payment Award Stock Options Valuation Assumptions Table [Text Block] Summary of RSU Activity Schedule Of Share Based Compensation Restricted Stock Units Award Activity Table [Text Block] Summary of Share-based Compensation Expense Classified in Consolidated Statements of Operations and Comprehensive Loss Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Future Minimum Lease Payments Under Operating Leases Schedule Of Future Minimum Rental Payments For Operating Leases Table [Text Block] Summary of Basic and Diluted Net Loss Per Ordinary Share Outstanding Schedule Of Earnings Per Share Basic And Diluted Table [Text Block] Anti-Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Ordinary Share Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Text Block] Geographical Statement Geographical [Axis] Geographical Segment Geographical [Domain] Singapore [Member] SINGAPORE Deferred Components of Benefit (Provision) for Income Taxes Schedule Of Components Of Income Tax Expense Benefit Table [Text Block] Reconciliation of Statutory Income Tax Rate Schedule Of Effective Income Tax Rate Reconciliation Table [Text Block] Components of Deferred Tax Assets and Liabilities Schedule Of Deferred Tax Assets And Liabilities Table [Text Block] Summary of Valuation Allowance Summary Of Valuation Allowance [Text Block] Summary of Activity in Unrecognized Tax Benefits Summary Of Income Tax Contingencies [Text Block] Schedule of Selected Quarterly Results from Operations Schedule Of Quarterly Financial Information Table [Text Block] Significant Accounting Policies [Line Items] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Lexington, MA. Lexington, MA [Member] Lexington M A [Member] Cambridge MA. Cambridge MA [Member] Cambridge M A [Member] Range Range [Axis] Range Range [Member] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Accounting Standards Update No. 2016-16 [Member] Accounting Standards Update201616 [Member] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Number of operating segment Number Of Operating Segments Cash, cash equivalents and restricted cash Schedule Of Property Plant And Equipment [Table] Schedule Of Property Plant And Equipment [Table] Property, Plant and Equipment, Type Property Plant And Equipment By Type [Axis] Property, Plant and Equipment, Type Property Plant And Equipment Type [Domain] Equipment, Furniture and Software. Equipment, Furniture and Software [Member] Equipment Furniture And Software [Member] Leasehold Improvements [Member] Leasehold Improvements [Member] Property Plant And Equipment [Line Items] Property Plant And Equipment [Line Items] Property and equipment, estimated useful lives Property Plant And Equipment Useful Life Property and equipment, estimated useful lives Property Plant And Equipment Estimated Useful Lives Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Start Date [Axis] Revenue recognition performance obligation, expected time satisfaction period Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 Revenue, practical expedient, incremental costs of obtaining contract Revenue Practical Expedient Incremental Cost Of Obtaining Contract Expected dividend rate Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate Income taxes examination likelihood of realization on settlement percentage. Description of Income tax benefit, likelihood of realized upon ultimate settlement Income Tax Examination Likelihood Of Unfavorable Settlement Income tax examination, likelihood of settlement, percentage Income Taxes Examination Likelihood Of Realization On Settlement Percentage Tax cuts and jobs act, change in tax rate, deferred tax assets and liabilities, income tax expense benefit. Benefit related to remeasurement of deferred tax assets and liabilities as result of filing tax return Tax Cuts And Jobs Act Change In Tax Rate Deferred Tax Assets And Liabilities Income Tax Expense Benefit Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Initial Application Period Cumulative Effect Transition Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition Initial Application Period Cumulative Effect Transition [Domain] As Originally Reported Under ASC 605 [Member] Calculated Under Revenue Guidance In Effect Before Topic606 [Member] Effect of Change [Member] Difference Between Revenue Guidance In Effect Before And After Topic606 [Member] Condensed Balance Sheet Statements Captions [Line Items] Condensed Balance Sheet Statements Captions [Line Items] Condensed Income Statement [Table] Condensed Income Statement [Table] Condensed Income Statements Captions [Line Items] Condensed Income Statements Captions [Line Items] Loss from operations Income tax benefit (provision) Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statements Captions [Line Items] Condensed Cash Flow Statements Captions [Line Items] Cumulative-effect adjustment to retained earnings New Accounting Pronouncement Or Change In Accounting Principle Cumulative Effect Of Change On Equity Or Net Assets1 Furniture and Equipment [Member] Furniture And Fixtures [Member] Software [Member] Software Development [Member] Fixed Assets in Progress [Member] Construction In Progress [Member] Property and equipment gross Property Plant And Equipment Gross Less accumulated depreciation Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Property and equipment, net Depreciation expense Accrued expenses and other current liabilities. Accrued compensation Employee Related Liabilities Current Accrued expenses related to CROs and CMOs Accrued Liabilities Current Accrued expenses and other current liabilities Accrued Expenses And Other Current Liabilities Total accrued expenses and other current liabilities Counterparty nominations number of research programs. Collaboration agreement upfront payment. Refundable collaborative arrangement allocable revenue. Collaboration and Share Purchase Agreements [Abstract] Collaboration And Share Purchase Agreements [Abstract] Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table] Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table] Type of Arrangement and Non-arrangement Transactions Type Of Arrangement [Axis] Arrangements and Non-arrangement Transactions Arrangements And Nonarrangement Transactions [Member] Research, license and option agreement. Research, License and Option Agreement [Member] Research License And Option Agreement [Member] Counterparty Name Counterparty Name [Axis] Counterparty Name Repurchase Agreement Counterparty Name [Domain] Pfizer Inc. Pfizer Inc. [Member] Pfizer Inc [Member] Collaboration and license agreement. Collaboration And License Agreement [Member] Collaboration And License Agreement [Member] Takeda pharmaceutical company limited. Takeda [Member] Takeda Pharmaceutical Company Limited [Member] Collaboration and share purchase agreements. Collaboration and Share Purchase Agreements [Member] Collaboration And Share Purchase Agreements [Member] Product and Service Product Or Service [Axis] Product and Service Products And Services [Domain] Category one programs. Category One Programs [Member] Category One Programs [Member] Category two programs. Category Two Programs [Member] Category Two Programs [Member] Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] Number of research programs, counterparty nomination Counterparty Nominations Number Of Research Programs Upfront payment under collaboration agreement Collaboration Agreement Upfront Payment Collaboration agreement refundable Refundable Collaborative Arrangement Allocable Revenue Shares issued under equity agreement Equity investment aggregate purchase price Purchase price per share Shares Issued Price Per Share Collaborative agreement research period. Research term description. Collaborative agreement research term Collaborative Agreement Research Period Research term, description Research Term Description Maximum termination notice period. Collaboration agreement termination period Maximum Termination Notice Period Collaboration agreement additional period after research term. Collaboration agreement, additional period after research program Collaboration Agreement Additional Period After Research Term Up-front consideration received. Up-front consideration received Up Front Consideration Received Collaboration agreement remaining research term. Revenue recognized Contract With Customer Liability Revenue Recognized Collaboration and license agreement, deferred revenue Contract With Customer Liability Collaboration and license agreement, deferred revenue current Remaining research term Collaboration Agreement Remaining Research Term Collaboration and license agreement month and year. Fund receivable for research and preclinical activities. Collaboration and license agreement research term. Collaboration agreement committed cash. Collaboration and license agreement month and year Collaboration And License Agreement Month And Year Fund receivable for research and preclinical activities Fund Receivable For Research And Preclinical Activities Research term under collaboration and license agreement Collaboration And License Agreement Research Term Collaboration agreement, committed cash Collaboration Agreement Committed Cash Equity investment agreement official closure date month and year. Purchase price per share Sale Of Stock Price Per Share Equity investment agreement official closure month and year Equity Investment Agreement Official Closure Date Month And Year Percentage of global costs and potential profits sharing ratio. Percentage of global costs and potential profits sharing ratio Percentage Of Global Costs And Potential Profits Sharing Ratio Maximum targets for preclinical programs. Option to reach maximum targets for preclinical programs. Maximum targets for preclinical programs Maximum Targets For Preclinical Programs Option to reach maximum targets for preclinical programs Option To Reach Maximum Targets For Preclinical Programs Collaboration agreement commencement date. Collaboration agreement commencement date Collaboration Agreement Commencement Date Collaboration revenue recognized Collaboration and license agreement, accounts receivable Contract With Customer Asset Net Collaboration and license agreement, accounts receivable current Contract With Customer Asset Net Current Schedule Of Stock By Class [Table] Schedule Of Stock By Class [Table] Sale of Stock Subsidiary Sale Of Stock [Axis] Sale of Stock Sale Of Stock Name Of Transaction [Domain] Follow-on underwritten public offering. Follow-On Underwritten Public Offering [Member] Follow On Underwritten Public Offering [Member] Class of Stock [Line Items] Class Of Stock [Line Items] Equity investment aggregate purchase price Gross proceeds from issuance of common stock. Gross proceeds from sale of ordinary shares Gross Proceeds From Issuance Of Common Stock Net proceeds from sale of ordinary shares Common stock, authorized Common Stock Shares Authorized Preferred stock, par value Preferred Stock No Par Value Preferred stock, shares authorized Preferred Stock Shares Authorized Common stock vote per share. Ordinary share holder, voting right Common Stock Voting Rights Voting rights, votes per share Common Stock Votes Per Share Preferred stock liquidation preference, per share Preferred Stock Liquidation Preference Plan Name Plan Name [Axis] Plan Name Plan Name [Domain] Two thousand fourteen equity incentive plan. 2014 Plan [Member] Two Thousand Fourteen Equity Incentive Plan [Member] Non employee stock option. Non-Employees Stock Option [Member] Non Employee Stock Option [Member] RSUs [Member] Restricted Stock Units R S U [Member] Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Research and Development Expenses [Member] Research And Development Expense [Member] Ordinary shares reserved for issuance Common Stock Capital Shares Reserved For Future Issuance Number of shares authorized (in shares) Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized Ordinary shares available for future grant Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Roll Forward Outstanding, Number of Shares, Beginning Balance Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Granted, Number of Shares Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross Exercised, Number of Shares Forfeited or cancelled, Number of Shares Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Outstanding, Number of Shares, Ending Balance Options exercisable, Number of Shares Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Options unvested, Number of Shares Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares Share-based compensation arrangement by share-based payment award options nonvested weighted average exercise price. Outstanding, Weighted Average Exercise Price, Beginning Balance Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Granted, Weighted Average Exercise Price Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price Exercised, Weighted Average Exercise Price Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price Forfeited or cancelled, Weighted Average Exercise Price Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price Outstanding, Weighted Average Exercise Price, Ending Balance Options exercisable, Weighted Average Exercise Price Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price Options unvested, Weighted Average Exercise Price Share Based Compensation Arrangement By Share Based Payment Award Options Nonvested Weighted Average Exercise Price Share based compensation arrangement by share based payment award options unvested weighted average remaining contractual term. Outstanding, Weighted Average Remaining Contractual Term Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2 Options exercisable, Weighted Average Remaining Contractual Term Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Weighted Average Remaining Contractual Term1 Options unvested, Weighted Average Remaining Contractual Term Share Based Compensation Arrangement By Share Based Payment Award Options Unvested Weighted Average Remaining Contractual Term Sharebased compensation arrangement by sharebased payment award options unvested intrinsic value. Outstanding, Aggregate Intrinsic Value Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value Options exercisable, Aggregate Intrinsic Value Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1 Options unvested, Aggregate Intrinsic Value Sharebased Compensation Arrangement By Sharebased Payment Award Options Unvested Intrinsic Value Vesting period Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 Contractual life of options Sharebased Compensation Arrangement By Sharebased Payment Award Expiration Period Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract] Risk-free interest rate, minimum Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate Minimum Risk-free interest rate, maximum Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate Maximum Expected term (in years) Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 Expected volatility, minimum Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate Minimum Expected volatility, maximum Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate Maximum Expected dividend yield Options to purchase common stock granted Outstanding, Number of Shares, Beginning Balance Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number Granted, Number of Shares Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Vested, Number of Shares Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Forfeited, Number of Shares Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Outstanding, Number of Shares, Ending Balance Outstanding, Average Grant Date Fair Value, Beginning Balance Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value Granted, Average Grant Date Fair Value Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value Vested, Average Grant Date Fair Value Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value Forfeited, Average Grant Date Fair Value Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value Outstanding, Average Grant Date Fair Value, Ending Balance Unrecognized stock-based compensation expense Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options Unrecognized stock-based compensation weighted average recognition period Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 Weighted average grant date fair value per granted option Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value Aggregate fair value of options vested Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 Unrecognized stock-based compensation expense Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Share Based Awards Other Than Options Fair value of RSUs vested Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] General and Administrative Expenses [Member] General And Administrative Expense [Member] Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Share-based compensation expense Lessee leasing arrangements operating leases renewal term description. Commitments And Contingencies [Line Items] Contingencies And Commitments [Table] Contingencies And Commitments [Table] Contingencies And Commitments [Table] Lease Arrangement, Type Lease Arrangement Type [Axis] Lease Arrangement, Type Lease Arrangement Type [Domain] Lexington MA operating lease agreement. 2016 Lexington, MA Lease [Member] Lexington M A Operating Lease Agreement [Member] Cambridge MA Operating Lease Agreement [Member] 2015 Cambridge, MA Lease [Member] Cambridge M A Operating Lease Agreement [Member] Commitments And Contingencies [Line Items] Commitments And Contingencies [Line Items] Lease agreement term Lessee Operating Lease Term Of Contract Lease renewal term description Lessee Leasing Arrangements Operating Leases Renewal Term Description Restricted cash Lease extension period Lessee Operating Lease Renewal Term Tenant improvement allowances received Payments For Proceeds From Tenant Allowance Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Operating Leases Future Minimum Payments Due [Abstract] 2019 Operating Leases Future Minimum Payments Due Current 2020 Operating Leases Future Minimum Payments Due In Two Years 2021 Operating Leases Future Minimum Payments Due In Three Years 2022 Operating Leases Future Minimum Payments Due In Four Years 2023 Operating Leases Future Minimum Payments Due In Five Years Thereafter Operating Leases Future Minimum Payments Due Thereafter Total Operating Leases Future Minimum Payments Due Lease rent expense Operating Leases Rent Expense Net Numerator: Net Income Loss [Abstract] Net loss attributable to ordinary shareholders Net Income Loss Available To Common Stockholders Basic Denominator: Weighted Average Number Of Shares Outstanding [Abstract] Weighted-average ordinary shares outstanding Net loss per share, basic and diluted Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Antidilutive Securities Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities, Name Antidilutive Securities Name [Domain] Options to Purchase Ordinary Shares [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Anti-dilutive shares excluded from calculation of diluted net loss per share Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Income Taxes [Line Items] Income Taxes [Table] Income Taxes [Table] Income Taxes [Table] United States [Member] UNITED STATES Japan [Member] JAPAN UK [Member] UNITED KINGDOM Ireland [Member] IRELAND Income Tax Authority Income Tax Authority [Axis] Income Tax Authority Income Tax Authority [Domain] Federal [Member] Domestic Country [Member] State [Member] State And Local Jurisdiction [Member] Tax Credit Carryforward Tax Credit Carryforward [Axis] Tax Credit Carryforward, Name Tax Credit Carryforward Name [Domain] Research and development tax credit carryforward. Research and development Research And Development Tax Credit Carryforward [Member] Orphan drug credits. Orphan Drug Credits [Member] Orphan Drug Credits [Member] Consolidated Entities Consolidated Entities [Axis] Consolidated Entities Consolidated Entities [Domain] Subsidiaries Outside of Singapore [Member] Subsidiaries [Member] Income Taxes [Line Items] Income Taxes [Line Items] U.S. federal corporate tax rate Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate Rest of World. Rest Of World [Member] Rest Of World [Member] Current benefit (provision) for income taxes: Current Income Tax Expense Benefit Continuing Operations [Abstract] Total current benefit (provision) income taxes Current Income Tax Expense Benefit Deferred benefit (provision) for income taxes: Deferred Income Tax Expense Benefit Continuing Operations [Abstract] Total deferred benefit (provision) income taxes Deferred Income Tax Expense Benefit Total benefit (provision) for income taxes Effective Income Tax Rate Reconciliation Permanent Differences Effective income tax rate reconciliation change in reserve for uncertain tax positions. Schedule Of Effective Income Tax Rate Reconciliation [Table] Schedule Of Effective Income Tax Rate Reconciliation [Table] Schedule Of Effective Income Tax Rate Reconciliation [Table] Singapore statutory income tax rate Federal and state tax credits Effective Income Tax Rate Reconciliation Tax Credits Permanent differences Effective Income Tax Rate Reconciliation Permanent Differences Changes in reserves for uncertain tax positions Effective Income Tax Rate Reconciliation Change In Reserve For Uncertain Tax Positions Foreign rate differential Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential Tax rate change Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate Other Effective Income Tax Rate Reconciliation Other Adjustments Change in deferred tax asset valuation allowance Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance Effective income tax rate Effective Income Tax Rate Continuing Operations Deferred tax assets tax deferred expense accumulated amortization. Deferred tax liabilities accumulated depreciation. Deferred tax assets: Deferred Tax Assets Net [Abstract] Net operating loss carryforwards Deferred Tax Assets Operating Loss Carryforwards Federal and state tax credits Deferred Tax Assets Tax Credit Carryforwards Accrued expenses Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities Share-based compensation Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost Accumulated amortization Deferred Tax Assets Tax Deferred Expense Accumulated Amortization Other Deferred Tax Assets Other Total deferred tax assets Deferred Tax Assets Gross Valuation allowance Deferred Tax Assets Valuation Allowance Net deferred tax assets Deferred Tax Assets Net Deferred tax liabilities: Deferred Tax Liabilities Net [Abstract] Accumulated depreciation Deferred Tax Liabilities Accumulated Depreciation Other Deferred Tax Liabilities Other Total deferred tax liabilities Deferred Income Tax Liabilities Net deferred tax assets (liabilities) Deferred Tax Assets Liabilities Net Deferred tax assets valuation allowance increase. Deferred tax assets valuation allowance reversal. Deferred tax assets valuation foreign currency translation. Deferred Tax Assets Net Of Valuation Allowance [Abstract] Balance at beginning of year Increase in valuation allowance Deferred Tax Assets Valuation Allowance Increase Reversal of valuation allowance Deferred Tax Assets Valuation Allowance Reversal Effect of foreign currency translation Deferred Tax Assets Valuation Foreign Currency Translation Balance at end of year Operating Loss Carry forward expiration year. Research and development tax credit carryforward expiration year. Tax credit carry forward expiration year Net operating loss carryforwards Operating Loss Carryforwards Net operating loss carryforwards available to offset future income tax liabilities indefinitely Deferred Tax Assets Operating Loss Carryforwards Not Subject To Expiration Net operating loss carryforwards available to offset future income tax liabilities Deferred Tax Assets Operating Loss Carryforwards Subject To Expiration Operating Loss Carry forward expiration year Operating Loss Carry Forward Expiration Year Research and development tax credit carryforward Tax Credit Carryforward Amount Research and development tax credit carryforward Research And Development Tax Credit Carryforward Expiration Year U.S.Orphan drug credit carryforward expiration year Tax Credit Carry Forward Expiration Year Operating loss carryforwards expiration year. Net operating loss carryovers Operating loss carryforwards expiration year Operating Loss Carryforwards Expiration Year Increase in valuation allowance Valuation Allowance Deferred Tax Asset Change In Amount Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns Roll Forward Unrecognized tax benefit at the beginning of the year Unrecognized Tax Benefits Tax positions related to prior years Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions Tax positions related to prior years Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions Tax positions related to the current year Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions Unrecognized tax benefit at the end of the year Gross unrecognized tax benefit Unrecognized tax benefit that could affect annual effective tax rate if recognized Unrecognized Tax Benefits That Would Impact Effective Tax Rate Interest and penalties related to uncertain tax positions Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued Tax years open to examination Open Tax Year Cash held by subsidiaries Cash Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract] Defined Contribution Plan [Table] Defined Contribution Plan [Table] Four Zero One K Plan [Member] 401(k) Plan [Member] Four Zero One K Plan [Member] Defined Contribution Plan Disclosure [Line Items] Defined Contribution Plan Disclosure [Line Items] Discretionary contributions to defined contribution pension plan Defined Contribution Plan Employer Discretionary Contribution Amount Schedule Of Related Party Transactions By Related Party [Table] Schedule Of Related Party Transactions By Related Party [Table] Related Party Related Party Transactions By Related Party [Axis] Related Party Related Party [Domain] Third-Party Investor [Member] Investor [Member] Shin Nippon Biomedical Laboratories Ltd. Shin Nippon Biomedical Laboratories Ltd. (SNBL) [Member] Shin Nippon Biomedical Laboratories Ltd [Member] Scientific Advisor [Member] Scientific Advisor [Member] Scientific Advisor [Member] Related Party Transaction Related Party Transaction [Axis] Related Party Transaction Related Party Transaction [Domain] Consulting Agreement [Member] Consulting Agreement [Member] Consulting Agreement [Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Related party transaction amount Related Party Transaction Amounts Of Transaction Payment for contract research services Related Party Transaction Expenses From Transactions With Related Party Agreement termination notice period. Consulting agreement termination notice period Agreement Termination Notice Period Consulting service expenses Professional And Contract Services Expense Selected Quarterly Financial Information [Abstract] Operating expenses Basic and diluted net loss per ordinary share Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type Subsequent Event Type [Axis] Subsequent Event Type Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Subsequent Event [Line Items] Subsequent Event [Line Items]