Entity Central Index Key Cover [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 Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Entity Shell Company Entity Shell Company Entity File Number Entity File Number Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address Address Line1 Entity Address, Address Line Two Entity Address Address Line2 Entity Address, City or Town Entity Address City Or Town Entity Address, State or Province Entity Address State Or Province Entity Address, Postal Zip Code Entity Address Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Entity Current Reporting Status Entity Current Reporting Status Document Quarterly Report Document Quarterly Report Document Transition Report Document Transition Report Entity Incorporation, State or Country Code Entity Incorporation State Country Code Entity Interactive Data Current Entity Interactive Data Current Title of 12(b) Security Security12b Title Security Exchange Name Security Exchange Name Carrying amount as of the balance sheet date, which is the fair value of the acquired in-process technology, adjusted for any amortization recognized after market feasibility has been achieved and for any impairment charges. Accrued liabilities and other liabilities current. Statement Of Financial Position [Abstract] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Goodwill Goodwill In-process research and development In Process Research And Development Property and equipment, net Property Plant And Equipment Net Right-of-use asset Operating Lease Right Of Use Asset Other non-current assets Other Assets Noncurrent Total assets Assets Liabilities and Stockholders’ Equity Liabilities And Stockholders Equity [Abstract] Current liabilities: Liabilities Current [Abstract] Accounts payable Accounts Payable Current Accrued expenses and other liabilities Accrued Liabilities And Other Liabilities Current Operating lease liability Operating Lease Liability Current Deferred revenue Deferred Revenue Current Total current liabilities Liabilities Current Long-term deferred revenue Deferred Revenue Noncurrent Deferred tax liability Deferred Income Tax Liabilities Net Other non-current liabilities Other Liabilities Noncurrent Total liabilities Liabilities Commitments and contingencies Commitments And Contingencies Stockholders’ equity: Stockholders Equity [Abstract] Common stock, $0.001 par value; 100,000,000 shares authorized at September 30, 2021 and December 31, 2020; 49,028,246 and 45,024,560 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively Common Stock Value Additional paid-in capital Additional Paid In Capital Common Stock Accumulated other comprehensive loss Accumulated Other Comprehensive Income Loss Net Of Tax Accumulated deficit Retained Earnings Accumulated Deficit Total stockholders’ equity Stockholders Equity Total liabilities and stockholders' equity Liabilities And Stockholders Equity Common stock, par value Common Stock Par Or Stated Value Per Share Common stock, shares authorized Common Stock Shares Authorized Common stock, shares issued Common Stock Shares Issued Common stock, shares outstanding Common Stock Shares Outstanding Research, development and patents expense. Income Statement [Abstract] Revenues Revenue From Contract With Customer Excluding Assessed Tax Operating expenses: Operating Expenses [Abstract] Research, development and patents Research Development And Patents Expense General and administrative General And Administrative Expense Total operating expenses Operating Expenses Operating loss Operating Income Loss Interest income Interest Income Other Other expense Other Nonoperating Income Expense Net loss applicable to common stockholders Net Income Loss Basic and diluted net loss per common share Earnings Per Share Basic And Diluted Shares used to compute basic and diluted net loss per common share Weighted Average Number Of Share Outstanding Basic And Diluted Net loss applicable to common stockholders Other comprehensive income (loss), net of tax: Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract] Foreign currency translation adjustments Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax Comprehensive loss Comprehensive Income Net Of Tax Stock issued during period value under at-the-market equity distribution and sales agreements. Statement Of Stockholders Equity [Abstract] Statement [Table] Statement [Table] Equity Components Statement Equity Components [Axis] Equity Component Equity Component [Domain] Common stock Common Stock [Member] Additional paid-in capital Additional Paid In Capital [Member] Accumulated other comprehensive loss Accumulated Other Comprehensive Income [Member] Accumulated deficit Retained Earnings [Member] Statement [Line Items] Statement [Line Items] Balance Balance, shares Shares Outstanding Share-based compensation Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Issuance of common stock for option exercises Stock Issued During Period Value Stock Options Exercised Issuance of common stock for option exercises, shares Stock Issued During Period Shares Stock Options Exercised Issuance of shares under an employee stock purchase plan (ESPP) Stock Issued During Period Value Employee Stock Purchase Plan Issuance of shares under an employee stock purchase plan (ESPP), shares Stock Issued During Period Shares Employee Stock Purchase Plans Issuance of common stock under at-the-market equity distribution and sales agreements, net of offering costs Stock Issued During Period Value Under At The Market Equity Distribution And Sales Agreements Stock issued during period shares under at-the-market equity distribution and sales agreements. Issuance of common stock under at-the-market equity distribution and sales agreements, net of offering costs, shares Stock Issued During Period Shares Under At The Market Equity Distribution And Sales Agreements Issuance of common stock in a private placement transaction, net of issuance costs Stock Issued During Period Value New Issues Issuance of common stock in a private transaction, net of issuance costs, shares Stock Issued During Period Shares New Issues Net loss Foreign currency translation adjustments Balance Balance, shares Noncash lease expense. Increase (decrease) in operating lease liability. Proceeds from issuance of common stock, exercise of common stock options. Statement Of Cash Flows [Abstract] Operating activities: Net Cash Provided By Used In Operating Activities [Abstract] Net loss Profit Loss Adjustments to reconcile net loss to net cash used in operating activities: Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Non-cash stock-based compensation Share Based Compensation Depreciation and amortization Depreciation Depletion And Amortization Non-cash lease expense Noncash Lease Expense Changes in assets and liabilities: Increase Decrease In Operating Capital [Abstract] Prepaid expenses and other assets Increase Decrease In Prepaid Deferred Expense And Other Assets Accounts payable, accrued liabilities and other liabilities Increase Decrease In Operating Liabilities Operating lease liabilities Increase Decrease In Operating Lease Liability Net cash used in operating activities Net Cash Provided By Used In Operating Activities Investing activities: Net Cash Provided By Used In Investing Activities [Abstract] Acquisition of property and equipment Payments To Acquire Property Plant And Equipment Net cash used in investing activities Net Cash Provided By Used In Investing Activities Financing activities: Net Cash Provided By Used In Financing Activities [Abstract] Proceeds from issuance of common stock and exercise of common stock options Proceeds From Issuance Of Common Stock Exercise Of Common Stock Options Common stock issuance costs Payments Of Stock Issuance Costs Proceeds from issuance of equity awards under ESPP Proceeds From Stock Plans Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Effect of exchange rate changes on cash and cash equivalents Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations Net change in cash and cash equivalents Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect Cash and cash equivalents, beginning of period Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations Cash and cash equivalents, end of period Supplemental disclosure of non-cash investing activities: Supplemental Cash Flow Information [Abstract] Right-of-use asset obtained in exchange for operating lease liability Right Of Use Asset Obtained In Exchange For Operating Lease Liability Quarterly Financial Information Disclosure [Abstract] Interim Financial Information Quarterly Financial Information [Text Block] Revenue From Contract With Customer [Abstract] Revenue Recognition Revenue From Contract With Customer [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements Fair Value Measurement Inputs Disclosure [Text Block] Leases [Abstract] Leases Lessee Operating Leases [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Stock-based Compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Equity [Abstract] Stockholders' Equity Stockholders Equity Note Disclosure [Text Block] Earnings Per Share [Abstract] Net Loss Per Share Earnings Per Share [Text Block] Accounting Policies [Abstract] Basis of Presentation Basis Of Accounting Policy Policy [Text Block] Reclassification Prior Period Reclassification Adjustment Description Principles of Consolidation Consolidation Policy [Text Block] Segment Reporting Segment Reporting Policy Policy [Text Block] Cash and Cash Equivalents Cash And Cash Equivalents Policy [Text Block] Research development and patents expense. Research Development And Patents Research Development And Patents Expense Policy [Text Block] Clinical trial accruals and prepaid expenses policy. Clinical Trial Accruals and Prepaid Expenses Clinical Trial Accruals And Prepaid Expenses Policy Policy [Text Block] Leases Lessee Leases Policy [Text Block] Impact of COVID-19, policy. Impact of COVID-19 on the Company's Business Impact Of C O V I D Nineteen Policy Policy [Text Block] Use of Estimates Use Of Estimates Recently adopted accounting pronouncements. Recently Adopted Accounting Pronouncements Recently Adopted Accounting Pronouncements Policy Policy [Text Block] Recently Issued Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Revenue Recognition Policy Revenue Recognition Policy [Text Block] Schedule of Maturities of Operating Lease Liabilities Lessee Operating Lease Liability Maturity Table [Text Block] Summary of Stock Option Activity and Related Information Schedule Of Share Based Compensation Stock Options Activity Table [Text Block] Summary of Stock-based Compensation Expenses Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Schedule of Assumptions Used in Estimating Fair Value of Options Granted and Performance-Based Stock Options Schedule Of Share Based Payment Award Stock Options Valuation Assumptions Table [Text Block] Research and development costs Research And Development Expense Patents expense. Patent-related expenses Patents Expense Change in Accounting Principle, Accounting Standards Update, Adoption Date Change In Accounting Principle Accounting Standards Update Adoption Date Change in Accounting Principle, Accounting Standards Update, Adopted [true false] Change In Accounting Principle Accounting Standards Update Adopted Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false] Change In Accounting Principle Accounting Standards Update Immaterial Effect Accounting Standards Update [Extensible List] Accounting Standards Update Extensible List Performance obligations payment refunded. Revenue Recognition [Abstract] Revenue Recognition Milestone Method [Table] Revenue Recognition Milestone Method [Table] Related Party Related Party Transactions By Related Party [Axis] Related Party Related Party [Domain] Kissei Pharmaceutical Co., Ltd. Kissei Pharmaceutical Co., Ltd Kissei Pharmaceutical Co Ltd [Member] Subsequent Event Type Subsequent Event Type [Axis] Subsequent Event Type Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Genzyme corporation. Genzyme Corporation Genzyme Corporation [Member] Revenue Recognition Milestone Method [Line Items] Revenue Recognition Milestone Method [Line Items] Deferred revenue related to research and development services Revenue relating to research and development services Research And Development Arrangement Contract To Perform For Others Compensation Earned Performance obligations payment refunded Performance Obligations Payment Refunded Business acquisition, payments Business Acquisition Cost Of Acquired Entity Transaction Costs Recognized revenue Contract With Customer Liability Revenue Recognized Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value Hierarchy and NAV Fair Value By Fair Value Hierarchy Level [Axis] Fair Value Hierarchy and NAV Fair Value Measurements Fair Value Hierarchy [Domain] Level 1 Fair Value Inputs Level1 [Member] Cash and Cash Equivalents Cash And Cash Equivalents [Axis] Cash and Cash Equivalents Restricted Cash And Cash Equivalents Cash And Cash Equivalents [Member] Money Market Funds Money Market Funds [Member] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Cash equivalents, fair value Cash And Cash Equivalents Fair Value Disclosure Lessee operating lease extended term of contract. Initially lease expiration date. Operating lease expiration date, month and year. Lease commenced date. Schedule of Lease Line Items Schedule of Lease Schedule Of Lease [Table] Schedule Of Lease [Table] Geographical Statement Geographical [Axis] Geographical Segment Geographical [Domain] U.S UNITED STATES Tokyo, Japan JAPAN Lease Contractual Term Lease Contractual Term [Axis] Lease Contractual Term Lease Contractual Term [Domain] New lease. New Lease New Lease [Member] Schedule Of Lease [Line Items] Schedule Of Lease [Line Items] Operating lease term Lessee Operating Lease Term Of Contract Operating lease initially expiration date Initially Lease Expiration Date Lessee, operating lease, existence of option to extend Lessee Operating Lease Existence Of Option To Extend Operating lease expiration date Lease Expiration Date1 Lease commenced date Lease Commenced Date Operating lease expiration date, month and year Operating Lease Expiration Date Month And Year Operating lease, auto-renewal term Lessee Operating Lease Renewal Term Operating lease, extension term Lessee Operating Lease Extended Term Of Contract 2021 Lessee Operating Lease Liability Payments Due Next Twelve Months 2022 Lessee Operating Lease Liability Payments Due Year Two 2023 Lessee Operating Lease Liability Payments Due Year Three 2024 Lessee Operating Lease Liability Payments Due Year Four 2025 Lessee Operating Lease Liability Payments Due Year Five Thereafter Lessee Operating Lease Liability Payments Due After Year Five Total lease payments Lessee Operating Lease Liability Payments Due Less imputed interest Lessee Operating Lease Liability Undiscounted Excess Amount Total lease liabilities Operating Lease Liability Current operating lease liabilities Non-current operating lease liabilities Operating Lease Liability Noncurrent Total operating lease liabilities Weighted-average remaining lease term Operating Lease Weighted Average Remaining Lease Term1 Weighted-average discount rate Operating Lease Weighted Average Discount Rate Percent Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Plan Name Plan Name [Axis] Plan Name Plan Name [Domain] Two thousand thirteen equity incentive plan. 2013 Plan Two Thousand Thirteen Equity Incentive Plan [Member] Two thousand four plan. 2004 Plan Two Thousand Four Plan [Member] Award Type Award Type [Axis] Award Type Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain] Stock Option Employee Stock Option [Member] Statistical Measurement Range [Axis] Statistical Measurement Range [Member] Minimum Minimum [Member] Maximum Maximum [Member] Sale of Stock Subsidiary Sale Of Stock [Axis] Sale of Stock Sale Of Stock Name Of Transaction [Domain] 2007 Employee Stock Purchase Plan Employee Stock [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Common stock reserved for future issuance Common Stock Capital Shares Reserved For Future Issuance Shares available for future grant Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Options granted expiration term Sharebased Compensation Arrangement By Sharebased Payment Award Expiration Period Stock option, vesting period Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 Number of Option Shares Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward Stock Options, Beginning Balance Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Stock Options, Granted Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross Stock Options, Exercised Stock Options, Cancelled Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Stock Options, Ending Balance Stock Options, Exercisable at June 30, 2021 Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Weighted Average Exercise Price, Beginning Balance Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Weighted Average Exercise Price, Granted Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price Weighted Average Exercise Price, Exercised Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price Weighted Average Exercise Price, Cancelled Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Expirations In Period Weighted Average Exercise Price Weighted Average Exercise Price, Ending Balance Weighted Average Exercise Price, Exercisable at June 30, 2021 Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price Stock issuance limit under employee stock purchase plan description. Annual increase in shares reserved for issuance. Annual increase in shares reserved for issuance as percentage of outstanding shares of common stock. Employee stock purchase plan offering period. Shares reserved, description Stock Issuance Limit Under Employee Stock Purchase Plan Description Increase in shares reserved for issuance Annual Increase In Shares Reserved For Issuance Increase in shares reserved for issuance as percentage of outstanding shares Annual Increase In Shares Reserved For Issuance As Percentage Of Outstanding Shares Of Common Stock Percentage of employee compensation for purchase of common stock under ESPP Share Based Compensation Arrangement By Share Based Payment Award Maximum Employee Subscription Rate Common stock fair market value, percentage Sharebased Compensation Arrangement By Sharebased Payment Award Purchase Price Of Common Stock Percent Employee stock purchase plan offering period Employee Stock Purchase Plan Offering Period Shares issued under ESPP Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Research and development and patents expense. Research, Development and Patents Research And Development And Patents Expense [Member] General and Administrative General And Administrative Expense [Member] Total stock-based compensation expense Allocated Share Based Compensation Expense Weighted-average assumptions for stock options and ESPP Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract] Risk-free interest rate Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate Expected volatility of common stock Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate Dividend yield Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate Expected term (in years) Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1 Unamortized compensation cost Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Unamortized compensation cost, vesting period Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 Percentage of commission on gross proceeds from sale of common stock, maximum. Counterparty Name Counterparty Name [Axis] Counterparty Name Repurchase Agreement Counterparty Name [Domain] B. Riley FBR, Inc. B. Riley FBR B Riley F B R Inc [Member] 2019 at market issuance sales agreement 2019 at-the-market issuance sales agreement Two Thousand Nineteen At Market Issuance Sales Agreement [Member] Private Placement Private Placement [Member] Stock purchase agreement, aggregate amount of common stock agreed to be purchased Common Stock Shares Subscriptions Sales commission as a percentage of gross proceeds Percentage Of Commission On Gross Proceeds From Sale Of Common Stock Maximum Share price per share Sale Of Stock Price Per Share Gross proceeds Proceeds From Issuance Of Common Stock Payments of stock issuance costs Potentially dilutive outstanding stock options excluded from diluted net loss per common share Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount