Entity Central Index Key Lessee operating lease liability payments due year four and thereafter 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 Current Reporting Status Entity Current Reporting Status 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 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 Interactive Data Current Entity Interactive Data Current Title of 12(b) Security Security12b Title Security Exchange Name Security Exchange Name Entity Incorporation, State or Country Code Entity Incorporation State Country Code Document Quarterly Report Document Quarterly Report Document Transition Report Document Transition Report Entity Common Stock, Shares Outstanding Entity Common Stock Shares Outstanding Statement Of Financial Position [Abstract] Statement [Table] Statement [Table] Class of Stock Statement Class Of Stock [Axis] Class of Stock Class Of Stock [Domain] Convertible Preferred Stock Convertible Preferred Stock [Member] Statement [Line Items] Statement [Line Items] Assets Assets [Abstract] Current assets: Assets Current [Abstract] Cash and cash equivalents Cash And Cash Equivalents At Carrying Value Short-term investments Available For Sale Securities Debt Securities Current Accounts receivable Accounts Receivable Net Current Prepaid expenses and other current assets Prepaid Expense And Other Assets Current Total current assets Assets Current Property and equipment, net Property Plant And Equipment Net Intangible assets, net Indefinite Lived Intangible Assets Excluding Goodwill Goodwill Goodwill Restricted cash Restricted Cash Noncurrent Operating lease right-of-use asset Operating Lease Right Of Use Asset Other 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 liabilities Accrued Liabilities Current Deferred revenue, current portion Contract With Customer Liability Current Total current liabilities Liabilities Current Deferred revenue, net of current portion Contract With Customer Liability Noncurrent Operating lease liabilities - long term Operating Lease Liability Noncurrent Total liabilities Liabilities Commitments and contingencies (Note 11) Commitments And Contingencies Stockholders' equity: Stockholders Equity [Abstract] Convertible preferred stock, $0.00001 par value; 10,000,000 shares authorized and no shares issued and outstanding at March 31, 2021 and December 31, 2020. Preferred Stock Value Common stock, $0.00001 par value; 150,000,000 shares authorized and 65,002,897 and 48,251,819 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively Common Stock Value Additional paid-in capital Additional Paid In Capital 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 Convertible Preferred stock, par value Preferred Stock Par Or Stated Value Per Share Convertible Preferred stock, shares authorized Preferred Stock Shares Authorized Convertible Preferred stock, shares issued Preferred Stock Shares Issued Convertible Preferred stock, shares outstanding Preferred Stock Shares Outstanding 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 Statement Of Income And Comprehensive Income [Abstract] Revenues Revenue From Contract With Customer Excluding Assessed Tax Type of Revenue [Extensible List] Type Of Revenue Extensible List 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 Interest income Investment Income Interest Other income, net Other Nonoperating Income Expense Loss before income taxes Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest Provision for (benefit from) income taxes Income Tax Expense Benefit Net income (loss) Net Income Loss Net income (loss) per share Earnings Per Share Basic And Diluted [Abstract] Basic Income Loss From Continuing Operations Per Basic Share Diluted Income Loss From Continuing Operations Per Diluted Share Shares used to compute net income (loss) per share Weighted Average Number Of Shares Outstanding [Abstract] Basic Weighted Average Number Of Shares Outstanding Basic Diluted Weighted Average Number Of Diluted Shares Outstanding Other comprehensive income: Other Comprehensive Income Loss Tax [Abstract] Unrealized gain on short-term investments, net of tax Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax Comprehensive income (loss) Comprehensive Income Net Of Tax Statement Of Stockholders Equity [Abstract] 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 Income/(Loss) Accumulated Other Comprehensive Income [Member] Accumulated Deficit Retained Earnings [Member] Beginning balance Beginning balance, shares Shares Issued Issuance of common stock in follow-on offering, net of issuance costs Stock Issued During Period Value New Issues Issuance of common stock in follow-on offering, net of issuance costs, shares Stock Issued During Period Shares New Issues Exercise of stock options Stock Issued During Period Value Stock Options Exercised Exercise of stock options, shares Stock Issued During Period Shares Stock Options Exercised Stock-based compensation Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Other comprehensive income Net income (loss) Ending balance Ending balance, shares Depreciation and amortization excluding amortization of intangible assets. Noncash lease expense. Increase decrease in accrued and other liabilities noncurrent. Statement Of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided By Used In Operating Activities [Abstract] Net income (loss) Profit Loss Adjustments to reconcile net income (loss) to net cash used in operating activities: Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Amortization of intangible assets Amortization Of Intangible Assets Depreciation and amortization Depreciation And Amortization Excluding Amortization Of Intangible Assets Amortization of premium (accretion of discounts) on investments Accretion Amortization Of Discounts And Premiums Investments Stock-based compensation expense Share Based Compensation Non-cash lease expense Noncash Lease Expense 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 and other long-term liabilities Increase Decrease In Accrued And Other Liabilities Noncurrent Deferred revenue Increase Decrease In Contract With Customer Liability 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] Purchases of property and equipment Payments To Acquire Property Plant And Equipment Purchases of short-term investments Payments To Acquire Available For Sale Securities Debt Maturities of short-term investments Proceeds From Sale Of Available For Sale Securities Debt Net cash provided by investing activities Net Cash Provided By Used In Investing Activities Cash flows from financing activities: Net Cash Provided By Used In Financing Activities [Abstract] Proceeds from issuance of common stock, net of issuance costs Proceeds From Issuance Of Common Stock Proceeds from exercise of stock options Proceeds From Stock Options Exercised Net cash provided by financing activities Net Cash Provided By Used In Financing Activities Net increase (decrease) in cash, cash equivalents and restricted cash Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding 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 Disclosure Text Block [Abstract] Description of the Business Nature Of Operations Accounting Policies [Abstract] Basis of Presentation and Summary of Significant Accounting Policies Basis Of Presentation And Significant Accounting Policies [Text Block] Earnings Per Share [Abstract] Net Income (Loss) Per Share Earnings Per Share [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements and Short-Term Investments Fair Value Disclosures [Text Block] Accrued Liabilities Current [Abstract] Accrued Liabilities Accounts Payable And Accrued Liabilities Disclosure [Text Block] Research and collaboration agreements. Organization Consolidation And Presentation Of Financial Statements [Abstract] Research and Collaboration Agreements Research And Collaboration Agreements [Text Block] License agreement. Research And Development [Abstract] License Agreements License Agreement Disclosure [Text Block] Common stock. Equity [Abstract] Common Stock Common Stock [Text Block] Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] Stock-Based Compensation Disclosure Of Compensation Related Costs Share Based Payments [Text Block] Leases [Abstract] Leases Lessee Operating Leases [Text Block] Commitments And Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments And Contingencies Disclosure [Text Block] Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Basis of Presentation Basis Of Accounting Policy Policy [Text Block] Unaudited interim financial information. Unaudited Interim Financial Information Unaudited Interim Financial Information Policy [Text Block] Use of Estimates Use Of Estimates Cash and Cash Equivalents Cash And Cash Equivalents Policy [Text Block] Restricted Cash Cash And Cash Equivalents Restricted Cash And Cash Equivalents Policy Short-term Investments Marketable Securities Policy Comprehensive Income (Loss) Comprehensive Income Policy Policy [Text Block] Revenue Recognition Revenue Recognition Policy [Text Block] Contract Balances Revenue From Contract With Customer Policy [Text Block] Research and Development Expenses Research And Development Expense Policy Stock-based Compensation Share Based Compensation Option And Incentive Plans Policy Leases Lessee Leases Policy [Text Block] Adopted Accounting Pronouncements New Accounting Pronouncements Policy Policy [Text Block] Schedule of cash, cash equivalents, and restricted cash. Schedule of Cash, Cash Equivalents, and Restricted Cash Schedule Of Cash Cash Equivalents And Restricted Cash Table [Text Block] Summary of Calculation of Basic and Diluted Net Income (Loss) Per Share Schedule Of Earnings Per Share Basic And Diluted Table [Text Block] Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Net Income (Loss) Per Share Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Text Block] Schedule of Short-Term Investments Subject to Fair Value Measurements on a Recurring Basis Schedule Of Fair Value Assets And Liabilities Measured On Recurring Basis Table [Text Block] Schedule of Accrued Liabilities Schedule Of Accrued Liabilities Table [Text Block] Schedule of Revenue by Collaboration Partners Disaggregation Of Revenue Table [Text Block] Summary of Contract Liabilities Contract With Customer Asset And Liability Table [Text Block] Schedule of Activities Under Company's Stock Option Plans Schedule Of Share Based Compensation Stock Options Activity Table [Text Block] Total Stock-based Compensation Recognized Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Text Block] Supplemental information related to leases. Summary of Supplemental Information Related to Leases Supplemental Information Related To Leases Table [Text Block] Schedule of Maturity of Operating Lease Liabilities Lessee Operating Lease Liability Maturity Table [Text Block] Cash And Cash Equivalents [Abstract] Restricted cash - non-current assets Total Summary of significant accounting policies. Summary of significant accounting policies. Summary Of Significant Accounting Policies [Table] Summary Of Significant Accounting Policies [Table] Accounting Standards Update Adjustments For New Accounting Pronouncements [Axis] Accounting Standards Update Type Of Adoption [Member] ASU 2019-12 Accounting Standards Update201912 [Member] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] 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 Numerator: Earnings Per Share Reconciliation [Abstract] Net income (loss) Denominator: Weighted Average Number Of Shares Outstanding Diluted Disclosure Items [Abstract] Basic Weighted Average Number Of Shares Outstanding Basic [Abstract] Weighted-average common shares used to calculate net income (loss) per share Diluted Effect of potentially dilutive securities: Weighted Average Number Diluted Shares Outstanding Adjustment [Abstract] Stock options and ESPP shares Incremental Common Shares Attributable To Share Based Payment Arrangements Weighted-average common shares, 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] Derivative Instrument Derivative Instrument Risk [Axis] Derivative Contract Derivative Contract Type [Domain] Options and ESPP to purchase common stock. Options and ESPP to purchase common stock Options And E S P P To Purchase Common Stock [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 securities excluded from computation of diluted net income (loss) per share Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Cash, cash equivalents and short term investments, amortized cost basis. Cash, cash equivalents and short term investments, allowance for credit loss. Cash, cash equivalents and short term investments, accumulated gross unrealized gain before tax. Cash, cash equivalents and short term investments, accumulated gross unrealized loss before tax. 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 I Fair Value Inputs Level1 [Member] Asset Class Fair Value By Asset Class [Axis] Asset Class Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation By Asset Class [Domain] Money market funds Money Market Funds [Member] Money market funds included in restricted cash. Restricted cash (money market funds) Money Market Funds Included In Restricted Cash [Member] U. S. Government bonds U S Treasury And Government [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] Amortized Cost Cash Cash Equivalents And Short Term Investments Amortized Cost Basis Allowance for Credit Losses Cash Cash Equivalents And Short Term Investments Allowance For Credit Loss Gross Unrealized Holding Gains Cash Cash Equivalents And Short Term Investments Accumulated Gross Unrealized Gain Before Tax Gross Unrealized Holding Losses Cash Cash Equivalents And Short Term Investments Accumulated Gross Unrealized Loss Before Tax Aggregate Fair Value Cash Cash Equivalents And Short Term Investments Restricted cash Restricted Cash And Cash Equivalents At Carrying Value Short-term Investments, Amortized Cost Available For Sale Debt Securities Amortized Cost Basis Short-term Investments, Allowance for Credit Losses Debt Securities Available For Sale Allowance For Credit Loss Short-term Investments, Gross Unrealized Holding Gains Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax Short-term Investments, Gross Unrealized Holding Losses Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax Short-term Investments, Aggregate Fair Value Available For Sale Securities Debt Securities Contractual maturities of greater than twelve months Available For Sale Securities Debt Maturities Within One Year Fair Value Accrued research and clinical current. Research and clinical expenses Accrued Research And Clinical Current Payroll and related expenses Employee Related Liabilities Current Legal and professional expenses Accrued Professional Fees Current Operating lease liabilities - short term Operating Lease Liability Current Other accrued expenses Other Accrued Liabilities Current Total Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table] Schedule Of Collaborative Arrangements And Noncollaborative Arrangement Transactions [Table] Counterparty Name Counterparty Name [Axis] Counterparty Name Repurchase Agreement Counterparty Name [Domain] AbbVie Ireland Unlimited Company. AbbVie Abb Vie Ireland Unlimited Company [Member] Amgen Inc. Amgen Amgen Inc [Member] Astellas Pharma Inc. Astellas Astellas Pharma Inc [Member] Bristol-Myers Squibb Company. Bristol Myers Squibb Bristol Myers Squibb Company [Member] Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] Revenue Revenues Percentage of net Income or net losses related to development and commercialization costs. Number of collaboration agreements. AbbVie Ireland Unlimited Company Collaborative Arrangement and Arrangement Other than Collaborative Type Of Arrangement [Axis] Collaborative Arrangement and Arrangement Other than Collaborative Arrangements And Nonarrangement Transactions [Member] Collaborative Arrangement Collaborative Arrangement [Member] Statistical Measurement Range [Axis] Statistical Measurement Range [Member] Maximum Maximum [Member] Minimum Minimum [Member] Geographical Statement Geographical [Axis] Geographical Segment Geographical [Domain] U.S UNITED STATES CD 71 agreement. CD71 Agreement C D71 Agreement [Member] Seattle genetics agreement. Seattle Genetics Agreement Seattle Genetics Agreement [Member] Discovery agreement. Discovery Agreement Discovery Agreement [Member] Contingent Consideration by Type Contingent Consideration By Type [Axis] Contingent Consideration Type Contingent Consideration Type [Domain] Development regulatory and commercial milestone payments. Development, Regulatory and Commercial Milestone Payments Development Regulatory And Commercial Milestone Payments [Member] Product and Service Product Or Service [Axis] Product and Service Products And Services [Domain] Second target. Second Target Second Target [Member] Timing of Transfer of Good or Service Timing Of Transfer Of Good Or Service [Axis] Timing of Transfer of Good or Service Timing Of Transfer Of Good Or Service [Domain] Transferred over Time Transferred Over Time [Member] Number of collaboration agreements Number Of Collaboration Agreements Percentage of net profits or net losses related to development and commercialization costs Percentage Of Net Income Or Net Losses Related To Development And Commercialization Costs Contingent payments receivable profit split on sales. Contingent payments receivable upon achieving development, regulatory and commercial milestones. Milestone payments received from revenue recognized during period. Payments of sublicense fees. Upfront payment received Proceeds From Collaborators Contingent payments receivable upon achieving development, regulatory and commercial milestones Contingent Payments Receivable Upon Achieving Development Regulatory And Commercial Milestones Profit split on U.S. sales Contingent Payments Receivable Profit Split On Sales Milestone payment received Milestone Payments Received From Revenue Recognized During Period Sublicense fees paid Payments Of Sublicense Fees Number of targets. Number of targets selected. Number of targets Number Of Targets Number of targets selected Number Of Targets Selected Milestone payment received. Future contingent milestone payment receivable. Milestone payments received Milestone Payment Received Contingent milestone payments receivable Contingent Milestone Payments Receivable Revenue recognized from collaborative arrangement Deferred revenue Contract With Customer Liability Amount due from agreement Contract With Customer Asset Net Period used to calculate weighted average price per share. Lock-up period for share transaction under collaboration and license agreement. Estimated premium on issuance of shares. Common stock shares issuable under agreement. Collaboration and license agreement. Collaboration and License Agreement Collaboration And License Agreement [Member] Amgen Inc EGFR Products. EGFR Products E G F R Products [Member] Amgen products. Amgen Products Amgen Products [Member] Amgen other products. Amgen Other Products Amgen Other Products [Member] Common stock, shares issuable under agreement Common Stock Shares Issuable Under Agreement Common stock, shares issuable under agreement, price per share Share Price Common stock, value of shares issued in connection with agreement Period used to calculate weighted average price per share Period Used To Calculate Weighted Average Price Per Share Lock-up period for share disposal Lock Up Period For Share Transaction Under Collaboration And License Agreement Estimated premium on the stock sold Estimated Premium On Issuance Of Shares Profit share upon exercise of co-development option. Percentage share of profit and losses Profit Share Upon Exercise Of Co Development Option Number of additional collaboration target. Number of additional collaboration target Number Of Additional Collaboration Target Contingent payments payable upon achieving development regulatory and commercial milestones. Contingent payments payable Contingent Payments Payable Upon Achieving Development Regulatory And Commercial Milestones Right to expand the number of additional collaboration target. Astellas Pharma Inc. Additional contingent payments. Additional Contingent Payments Additional Contingent Payments [Member] Right to expand the number of additional collaboration target Right To Expand Number Of Additional Collaboration Target Amount due from customer Number of oncology target. Number of collaboration target. Collaboration target research term. Period of nomination of additional target. Extension of research term for each collaboration target. Increments of extended collaboration target research times. Bristol Myers Squibb Company Achieving additional targets. Each Of Two Additional Targets Achieving Additional Targets [Member] Number of oncology target Number Of Oncology Target Number of collaboration target Number Of Collaboration Target Collaboration target research term Collaboration Target Research Term Research terms Research And Development Arrangement Contract To Perform For Others Description And Terms Period of nomination of additional target from effective date Period Of Nomination Of Additional Target Extension of research term for each collaboration target Extension Of Research Term For Each Collaboration Target Times of increments for extended collaboration target research time Increments Of Extended Collaboration Target Research Times Number of research targets selected. Number of research targets selected Number Of Research Targets Selected Aggregate collaboration transaction amount. Upfront fee received. Research and development service fees. Estimated research service termination date. Total transaction price Aggregate Collaboration Transaction Amount Upfront payment received Upfront Fee Received Research and development service fees Research And Development Service Fees Estimated research service termination date Estimated Research Service Termination Date Cash payment to execute the agreement. ImmunoGen, Inc. Immuno Gen Inc Immuno Gen Inc [Member] Upfront cash payment Cash Payment To Execute Agreement Milestone payment payable. Milestone payments payable Milestone Payment Payable Charge to research and development expense Contract with customer liability additions. Revenue From Contract With Customer [Abstract] Balance at 12/31/2020 Additions Contract With Customer Liability Additions Deductions Contract With Customer Liability Revenue Recognized Balance at 3/31/2021 Contract with customer liability maturity month and year. First target under discovery agreement. First Target under Discovery Agreement First Target Under Discovery Agreement [Member] Second target under discovery agreement. Second Target under Discovery Agreement Second Target Under Discovery Agreement [Member] Deferred revenue recognition maturity month and year Contract With Customer Liability Maturity Month And Year Sublicense fees. Milestone payment receivable. Additional sublicense fees. Schedule Of Research And Development Arrangement Contract To Perform For Others [Table] Schedule Of Research And Development Arrangement Contract To Perform For Others [Table] Research and Development Arrangement, Contract to Perform for Others, Type Research And Development Arrangement Contract To Perform For Others By Type [Axis] Research and Development Arrangement, Contract to Perform for Others, Type Research And Development Arrangement Contract To Perform For Others Type [Domain] University of California, Santa Barbara. UCSB University Of California Santa Barbara [Member] License Agreement [Line Items] Research And Development Arrangement Contract To Perform For Others [Line Items] Sublicense fees Sublicense Fees Milestone payment receivable Milestone Payment Receivable Additional sublicense fees Additional Sublicense Fees Accrued liabilities Option period granted to underwriters to purchase additional shares. 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] Underwritten public offering. Underwritten Public Offering Underwritten Public Offering [Member] Underwriters Over Allotment Option [Member] Class Of Stock [Line Items] Class Of Stock [Line Items] Issuance of common stock in follow-on offering, net of issuance costs, shares Common stock price, per share Shares Issued Price Per Share Underwriting discounts and commissions and offering expenses Payments Of Stock Issuance Costs Period granted to underwriters to purchase additional shares Option Period Granted To Underwriters To Purchase Additional Shares Number of Options Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward Balances, beginning of the period Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number Options granted Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross Options exercised Option forfeited/expired Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period Balances, end of the period Options exercisable, end of the period Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number Options Outstanding, Weighted-Average Exercise Price Per Share Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Rollforward Balances, beginning of the period Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price Options granted Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price Options exercised Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price Option forfeited/expired Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price Balances, end of the period Options exercisable, end of the period Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Income Statement Location Income Statement Location [Axis] Income Statement Location Income Statement Location [Domain] Research and development Research And Development Expense [Member] General and administrative General And Administrative Expense [Member] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Stock-based compensation expense: Share Based Compensation [Abstract] Stock-based compensation expense Allocated Share Based Compensation Expense Schedule Of Operating Leased Assets [Table] Schedule Of Operating Leased Assets [Table] Finite-Lived Intangible Assets by Major Class Finite Lived Intangible Assets By Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name Finite Lived Intangible Assets Major Class Name [Domain] New Lease Agreement Lease Agreements [Member] Lease Contractual Term Lease Contractual Term [Axis] Lease Contractual Term Lease Contractual Term [Domain] First year of lease term. First year of lease term First Year Of Lease Term [Member] Second twelve months of lease term. Second twelve months of lease term Second Twelve Months Of Lease Term [Member] Tenth year of lease term. Tenth year of lease term Tenth Year Of Lease Term [Member] Credit Facility Credit Facility [Axis] Credit Facility Credit Facility [Domain] Letter of Credit Letter Of Credit [Member] Operating Leased Assets [Line Items] Operating Leased Assets [Line Items] Area of rentable office and laboratory space Area Of Land Lease term description Lessee Operating Lease Description Initial lease term Lessee Operating Lease Term Of Contract Extended lease term Lessee Operating Lease Renewal Term Operating leases rent expense annual base rent. Maximum improvement allowance. Improvement allowance from recoverable rent. Annual lease rent Operating Leases Rent Expense Annual Base Rent Maximum one-time improvement allowance Maximum Improvement Allowance Improvement allowance from recoverable rent Improvement Allowance From Recoverable Rent Letter of credit outstanding, amount Letters Of Credit Outstanding Amount Rent expense Operating Lease Expense Cash paid for amounts included in measurement of lease liabilities. Supplemental balance sheet information related to leases. Weighted average remaining lease term. Weighted average discount rate. Cash paid for amounts included in the measurement of lease liabilities Cash Paid For Amounts Included In Measurement Of Lease Liabilities [Abstract] Operating cash flows from operating leases Operating Lease Payments Supplemental balance sheet information related to leases: Supplemental Balance Sheet Information Related To Leases [Abstract] Operating lease right-of-use assets Current operating lease liabilities Non-current operating lease liabilities Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Operating Lease Liability Current Statement Of Financial Position Extensible List Total operating lease liabilities Operating Lease Liability Weighted-average remaining lease term (in years) Weighted Average Remaining Lease Term [Abstract] Operating lease Operating Lease Weighted Average Remaining Lease Term1 Weighted-average discount rate Weighted Average Discount Rate [Abstract] Operating lease Operating Lease Weighted Average Discount Rate Percent Maturity of operating lease liabilities Operating Lease Liabilities Payments Due [Abstract] 2021 Lessee Operating Lease Liability Payments Remainder Of Fiscal Year 2022 Lessee Operating Lease Liability Payments Due Next Twelve Months 2023 Lessee Operating Lease Liability Payments Due Year Two 2024 Lessee Operating Lease Liability Payments Due Year Three 2025 and beyond Lessee Operating Lease Liability Payments Due Year Four And Thereafter Total lease payments Lessee Operating Lease Liability Payments Due Less imputed interest Lessee Operating Lease Liability Undiscounted Excess Amount Present value of lease liabilities Loss contingency answer, affirmative defenses and counterclaims filing date. Loss contingency, answer and counterclaims by plaintiff filing date. Loss Contingencies [Table] Loss Contingencies [Table] Litigation Case Litigation Case [Axis] Litigation Case Litigation Case Type [Domain] Patent infringement lawsuit. Patent Infringement Lawsuit Patent Infringement Lawsuit [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Lawsuit filed date Loss Contingency Lawsuit Filing Date Name of plaintiff Loss Contingency Name Of Plaintiff Loss contingency, answer, affirmative defenses and counterclaims filing date Loss Contingency Answer Affirmative Defenses And Counterclaims Filing Date Loss contingency claim amount Loss Contingency Estimate Of Possible Loss Loss contingency, answer and counterclaims by plaintiff filing date Loss Contingency Answer And Counterclaims By Plaintiff Filing Date Net operating loss carryback. Percentage of taxable income from net operating losses for suspension of annual deduction limitation. Net operating loss carryback Net Operating Loss Carryback Period Percentage of taxable income from net operating losses for suspension of annual deduction limitation Percentage Of Taxable Income From Net Operating Losses For Suspension Of Annual Deduction Limitation