Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Collaborative Arrangement and Arrangement Other than Collaborative Document Transition Report Document Transition Report Debt Securities, Available-for-Sale, Amortized Cost, Current Amortized Cost, Short-term marketable securities Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Expected volatility Money Market Funds [Member] Money market fund Increase (Decrease) in Other Accrued Liabilities Other accrued expenses Restructuring and Related Cost, Number of Positions Eliminated, Period Percent Percentage of workforce reduced Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other current assets Restricted Stock Units (RSUs) [Member] RSUs Unvested RSUs Fair Value, Inputs, Level 1 [Member] Level 1 Potential Milestone Payments. Potential Milestone Payments Potential milestone payments Lessee, operating lease, lease not yet commenced, operating lease right-of-use asset Lessee, Operating Lease, Lease Not yet Commenced, Right Of Use Asset Lessee, operating lease, lease not yet commenced, right-of-use asset. Percentage of premium to weighted average price immediately prior to delivery of notice of closing date Percentage of Premium to Weighted Average Price Immediately Prior to Delivery of Notice of Closing Date Percentage of premium to weighted average price immediately prior to delivery of notice of closing date. Cash equivalents at carrying value and available for sale debt securities gross unrealized gain. Cash Equivalents At Carrying Value And Available For Sale Debt Securities Gross Unrealized Gain Gross Unrealized Gain Subsequent Event Subsequent Events [Text Block] Milestones and Research Agreements Milestones And Research Agreements [Text Block] Milestones and Research Agreements Operating Lease, Liability, Noncurrent Operating lease liabilities - long-term Balance Sheet Location [Axis] Balance Sheet Location Assets, Current Total current assets Liabilities and Equity Total liabilities and stockholders' equity Entity Address, State or Province Entity Address, State or Province Stock Issued During Period, Value, New Issues Issuance of common stock under at-the-market (ATM) equity offering program, net of issuance costs Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive loss Fifth Year of Collaboration Agreement Fifth Year of Collaboration [Member] Fifth year of collaboration. Trading Symbol Trading Symbol Common Stock, Shares, Issued Common stock, shares issued Debt Securities, Available-for-Sale [Line Items] Investments in marketable securities: Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Net Income (Loss) Attributable to Parent [Abstract] Numerator: Shares, Outstanding Balance (in shares) Balance (in shares) Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Entity Address, City or Town Entity Address, City or Town Regulatory and Commercial Milestones Regulatory And Commercial Milestones [Member] Regulatory and commercial milestones. Subsequent Event Subsequent Event [Member] Subsequent Event Type [Axis] Cash and cash equivalent gross unrealized loss. Cash And Cash Equivalent Gross Unrealized Loss Gross Unrealized Loss Collaboration Agreement Collaboration Agreement [Abstract] Additional Paid-in Capital [Member] Additional Paid-in Capital Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Proceeds from maturities of marketable securities Liabilities, Current [Abstract] Current liabilities Assets, Current [Abstract] Current assets Counterparty Name [Axis] Preferred Stock, Par or Stated Value Per Share Preferred stock, par value Statement of Stockholders' Equity [Abstract] Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false] Operating Lease, Liability, Current Operating lease liabilities - short-term Revenue from Contract with Customer, Including Assessed Tax Collaboration revenue Property, Plant and Equipment, Net Property and equipment, net Property, Plant and Equipment, Net, Total Restructuring Charges, Total Restructuring Charges Costs incurred Restructuring charges Scenario [Domain] Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Collaborative Arrangement and Arrangement Other than Collaborative Entity Central Index Key Entity Central Index Key Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Issuance of common stock for settlement of restricted stock units (RSUs) Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures, Total Percentage share of profits and operating loss for products Percentage Share of Profits and Operating Loss for Products Percentage share of profits and operating loss for products. Change in Accounting Principle, Accounting Standards Update, Adopted [true false] Subsidiary or Equity Method Investee, Sale of Stock by Subsidiary or Equity Investee [Table] Subsidiary Or Equity Method Investee Sale Of Stock By Subsidiary Or Equity Investee [Table] Assets, Fair Value Disclosure Total assets measured at fair value Preferred Stock, Shares Outstanding Preferred stock, shares outstanding Preferred Stock, Shares Outstanding, Beginning Balance Preferred Stock, Shares Outstanding, Ending Balance Liabilities, Current Total current liabilities Entity Tax Identification Number Entity Tax Identification Number Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Financial Instruments [Domain] Financial Instruments Stock Issued During Period, Value, Employee Stock Purchase Plan Issuance of common stock under Employee Stock Purchase Plan (ESPP) Leases Lessee, Operating Leases [Text Block] Lessee, Operating Lease, Lease Not yet Commenced, Existence of Option to Extend [true false] Assets Total assets Operating Lease, Right-of-Use Asset Operating lease right-of-use (ROU) assets Entity Registrant Name Entity Registrant Name Asset-Backed Securities [Member] Asset-backed securities Retained Earnings (Accumulated Deficit) Accumulated deficit Retained Earnings (Accumulated Deficit), Total Retained Earnings [Member] Accumulated Deficit Stock Issued During Period, Shares, Employee Stock Purchase Plans Issuance of common stock under Employee Stock Purchase Plan (ESPP) (in shares) Minimum [Member] Minimum Schedule of Available-for-Sale Securities Reconciliation [Table Text Block] Schedule of Investments in Marketable Securities Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Employee severance and related benefits Severance Costs Forecast Forecast [Member] US Government Agencies Debt Securities [Member] U.S and foreign corporate debt securities Equity Component [Domain] Equity Component Employee Stock Option [Member] Options Options to purchase common stock Change in Accounting Principle, Accounting Standards Update, Adoption Date Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net loss to net cash used in operating activities: Measurement Frequency [Axis] Measurement Frequency Entity Current Reporting Status Entity Current Reporting Status Common Stock, Shares Authorized Common stock, shares authorized Research and Development Expense Research and development Research and development expense Research and Development Expense, Total Assets [Abstract] ASSETS Proceeds from Issuance of Common Stock Proceeds from the issuance of common stock under ATM equity offering program, net of issuance costs Subsidiary, Sale of Stock [Line Items] Subsidiary Sale Of Stock [Line Items] Fair value measurements and investments in marketable securities. Fair Value Measurements And Investments In Marketable Securities [Text Block] Fair Value Measurements and Investments in Marketable Securities Common stock, $0.001 par value; 150,000,000 shares authorized as of September 30, 2023 and December 31, 2022; 52,614,194 and 48,894,973 shares issued and outstanding as of September 30, 2023 and December 31, 2022, respectively Common Stock, Value, Issued Accrued Liabilities, Current Total accrued expenses Current Fiscal Year End Date Current Fiscal Year End Date Share-Based Payment Arrangement, Noncash Expense Stock-based compensation Share-Based Payment Arrangement, Noncash Expense, Total Operating Income (Loss) Loss from operations Cash equivalents at carrying value and available for sale debt securities estimated fair value. Cash Equivalents At Carrying Value And Available For Sale Debt Securities Estimated Fair Value Fair Value Percentage cover of research and development costs Percentage Cover of Research and Development Costs Percentage cover of research and development costs. Lessee, Operating Lease, Lease Not yet Commenced, Option to Extend Lessee, operating lease, lease not yet commenced, option to extend Research and Development Expense [Member] Research and Development Expenses Research and Development Number of fellow-contributed programs Number of Fellow-contributed Programs Number of fellow-contributed programs. Payments for Restructuring Reductions for cash payments Accounts Payable and Accrued Liabilities Disclosure [Text Block] Other Accrued Expenses Share-Based Payment Arrangement, Expense Stock-based compensation expense Seventh Year of Collaboration Agreement Seventh Year of Collaboration [Member] Seventh year of collaboration. Restructuring one-time termination Cost Restructuring one-time termination Cost Restructuring one time termination cost. Number of directors, right to designate in company board Number of Directors, Right to Designate in Board Number of directors right to designate in board. Threshold payment of opt-in fee Threshold Payment of Opt-in Fee Threshold payment of opt-in fee. Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table] Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Earnings Per Share, Policy [Policy Text Block] Net Loss per Share Represents the number of approved products. Number Of Approved Products FDA approved products (in products) Sale of stock, price per share Sale of Stock, Price Per Share Cumulative restructuring charges Cumulative Restructuring Charges Cumulative Restructuring Charges Operating Expenses [Abstract] Operating expenses Subsequent Events [Abstract] Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other comprehensive loss Available for sale debt securities accumulated gross unrealized gain before tax current. Available for Sale Debt Securities Accumulated Gross Unrealized Gain before Tax Current Gross Unrealized Gain, Short-term marketable securities Other Assets, Noncurrent Other assets Other Accrued Liabilities, Current Other accrued expenses Equity [Text Block] Sale of Common Stock Share based compensation arrangement fair value assumptions exercise price. Share Based Compensation Arrangement Fair Value Assumptions Exercise Price Exercise price Equity, Attributable to Parent [Abstract] Stockholders' equity Increase (decrease) in accrued research and development expenses. Increase Decrease In Accrued Research And Development Expenses Accrued research and development expenses Two thousand and twenty at the market offerings. Two Thousand And Twenty At The Market Offerings [Member] 2020 At the Market Offerings Accounting Policies [Abstract] Scenario [Axis] Upfront equity investment Sale of Stock, Consideration Received on Transaction Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award Other Noncurrent Assets [Member] Other Assets Monthly sublease base rent. Monthly Sublease Base Rent Monthly sublease base rent Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract Lease not yet commence, term of contract Earnings Per Share, Basic Net loss per share, basic Net loss per share - basic Earnings Per Share, Basic, Total Purchase price per share of additional shares description Purchase Price Per Share of Additional Shares Description Purchase price per share of additional shares description. Commitments and Contingencies Commitments and contingencies Income Statement [Abstract] Marketable securities - short-term Short-term marketable securities Fair Value, Short-term marketable securities Statistical Measurement [Domain] Statistical Measurement Net Cash Provided by (Used in) Operating Activities Net cash used in operating activities Incremental costs. Incremental Costs Incremental costs Document Period End Date Document Period End Date Statistical Measurement [Axis] Statistical Measurement Earnings Per Share, Diluted Net loss per share, diluted Net loss per share - diluted Earnings Per Share, Diluted, Total Short-Term Investments [Abstract] Short-term marketable securities Proceeds from the issuance of common stock under ESPP Proceeds From Issuance Of Common Stock Under Employee Stock Purchase Plan Proceeds from issuance of common stock under employee stock purchase plan. Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV Fair Value, Recurring [Member] Recurring Additional Paid in Capital, Common Stock Additional paid-in capital US Treasury Securities [Member] U.S. treasury securities Accrued balance as of September 30, 2023 Accrued balance as of December 31, 2022 Accrued restructuring charges current. Accrued Restructuring Charges Current Accrued restructuring charges Schedule of Restructuring and Related Costs [Table] Accrued research and development expenses current. Accrued Research And Development Expenses Current Accrued research and development expenses Liabilities and Equity [Abstract] LIABILITIES AND STOCKHOLDERS' EQUITY Cash equivalents at carrying value and available for sale debt securities gross unrealized loss. Cash Equivalents At Carrying Value And Available For Sale Debt Securities Gross Unrealized Loss Gross Unrealized Loss Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Interactive Data Current Entity Interactive Data Current Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accounts Payable, Total Equity [Abstract] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Equity Components [Axis] Equity Components Increase (Decrease) in Accounts Receivable Accounts receivable from collaboration Restructuring and Related Activities [Abstract] Investments, Debt and Equity Securities [Abstract] Increase decrease in operating lease liabilities. Increase Decrease In Operating Lease Liabilities Operating lease liabilities Local Phone Number Local Phone Number Sale of Stock [Axis] Sale of Stock Issuance of common stock for settlement of restricted stock units (RSUs) (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures, Total Other risks and uncertainties. Other Risks And Uncertainties Policy [Text Block] Other Risks and Uncertainties Statement of Cash Flows [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax, Total Proceeds received in collaboration agreement Proceeds from Collaborators Common Stock, Par or Stated Value Per Share Common stock, par value Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Unrecognized stock-based compensation expense expected to be recognized, term Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Maximum [Member] Maximum Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Nature of Business Restructuring costs reversal Restructuring Costs Reversal of stock-based compensation expense Restructuring costs reversal of stock-based compensation expense Number of years of standstill and lockup provisions Number of Years of Standstill and Lockup Provisions Number of years of standstill and lockup provisions. Fair Value, Inputs, Level 3 [Member] Level 3 APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Stock-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition, Total Cash equivalents at fair value. Cash Equivalents At Fair Value [Abstract] Cash equivalents Research and Development Arrangement, Contract to Perform for Others [Line Items] Research And Development Arrangement Contract To Perform For Others [Line Items] Milestone and Research Agreements: Net (decrease) increase in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Payables and Accruals [Abstract] General and Administrative Expense [Member] General and Administrative Expenses General and Administrative Long-Term Investments [Abstract] Long-term marketable securities Lessee, operating lease, lease not yet commenced, future lease payments Lessee, Operating Lease, Lease Not yet Commenced, Payments Due Lessee, operating lease, lease not yet commenced, payments due. Upfront cash payment received. Upfront Cash Payment Received Upfront cash payment received Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share City Area Code City Area Code Research and Development Arrangement, Contract to Perform for Others, Type [Axis] Research and Development Arrangement, Contract to Perform for Others, Type Net Cash Provided by (Used in) Operating Activities [Abstract] Cash flows from operating activities Interest Income, Other Interest and other income, net Schedule of accrued restructuring charges. Schedule Of Accrued Restructuring Charges [Table TextBlock] Schedule of Accrued Restructuring Charges Milestones and Research Agreements Milestones And Research Agreements [Abstract] General and Administrative Expense General and administrative General and Administrative Expense, Total Weighted Average Number of Shares Outstanding, Basic Weighted average common shares outstanding, basic Weighted Average Number of Shares Outstanding, Basic, Total Weighted average common shares outstanding - basic Research and Development Arrangement, Contract to Perform for Others, Type [Domain] Research and Development Arrangement, Contract to Perform for Others, Type Net Cash Provided by (Used in) Financing Activities [Abstract] Cash flows from financing activities Statement [Table] Statement [Table] Fair value assets between levels transfers amount. Fair Value Assets Between Levels Transfers Amount Fair value assets transfers between level 1, level 2 or level 3 Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Summary of Assumptions Used to Estimate Fair Values of Stock Options Grants Document Fiscal Period Focus Document Fiscal Period Focus Accrued Professional Fees, Current Accrued professional fees and other Statement [Line Items] Statement [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive securities excluded from computation of loss per share Subsequent Event [Line Items] Accounts receivable from collaboration Accounts Receivable, after Allowance for Credit Loss, Current Accounts Receivable, after Allowance for Credit Loss, Current, Total Cash equivalents at carrying value and available for sale debt securities amortized cost. Cash Equivalents At Carrying Value And Available For Sale Debt Securities Amortized Cost Amortized Cost Common Stock [Member] Common Stock Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Amortized Cost Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Schedule of Recognized Stock-Based Compensation Expense Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Proceeds from Sale of Debt Securities, Available-for-Sale Proceeds from sale of marketable securities Antidilutive Securities, Name [Domain] Antidilutive Securities, Name Accounting Standards Update 2016-13 [Member] ASU 2016-13 Cover [Abstract] Document Fiscal Year Focus Document Fiscal Year Focus BeiGene agreement. Bei Gene Agreement [Member] BeiGene Agreement Sale of Stock [Domain] Sale of Stock Security Exchange Name Security Exchange Name Third Year of Collaboration Agreement Third Year of Collaboration [Member] Third year of collaboration. Schedule of available for sale securities1. Schedule Of Available For Sale Securities1 [Table] Recently Adopted Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Preferred Stock, Shares Issued Preferred stock, shares issued Preferred Stock, Shares Authorized Preferred stock, shares authorized Significant accounting policies. Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Percentage of then-outstanding voting capital stock subject to stockholder approval Percentage of Then-outstanding Voting Capital Stock Subject to Stockholder Approval Percentage of then-outstanding voting capital stock subject to stockholder approval. Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Operating lease liabilities arising from obtaining ROU assets Financial Instrument [Axis] Financial Instrument Weighted Average Number of Shares Outstanding, Diluted [Abstract] Denominator: Entity Emerging Growth Company Entity Emerging Growth Company Deferred Compensation Liability [Abstract] Milestone payment, diligence maintenance fees. Milestone Payment Diligence Maintenance Fees Milestone payment, diligence maintenance fees Amendment Flag Amendment Flag Schedule of Accrued Liabilities [Table Text Block] Schedule of Other Accrued Expenses Collaboration term Collaboration Term Collaboration term. Accounting Standards Update [Domain] Basis of Accounting, Policy [Policy Text Block] Basis of Presentation U.S. and foreign commercial paper. U S And Foreign Commercial Paper [Member] U.S. and foreign commercial paper Restructuring and Related Activities Disclosure [Text Block] Restructuring Payments to Acquire Debt Securities, Available-for-Sale Purchases of marketable securities Leases [Abstract] Securities Act File Number Entity File Number Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] Gilead Sciences, Inc. Gilead Sciences Incorporated [Member] Gilead sciences incorporated. Unrealized gain (loss) on marketable securities Unrealized gain (loss) on marketable debt securities OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Cash Equivalents [Member] Cash equivalents Share-Based Payment Arrangement [Abstract] Accounts Payable, Current Accounts payable Accounts Payable, Current, Total Lessee, operating lease, lease not yet commenced, operating lease liability Lessee, Operating Lease, Lease Not yet Commenced, Lease Liability Lessee, operating lease, lease not yet commenced, lease liability. Operating Expenses Total operating expenses Number of timepoints of program Number of Timepoints of Program Number of timepoints of program. Arbutus biopharma agreement. Arbutus Biopharma Agreement [Member] Arbutus Biopharma Agreement Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Expected term (years) Debt Securities, Available-for-Sale, Noncurrent Fair Value, Long-term marketable securities Long-term marketable securities Entity Address, Address Line Two Entity Address, Address Line Two Preferred Stock, Value, Issued Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding Entity Small Business Entity Small Business Entity Shell Company Entity Shell Company Number of Operating Segments Operating segments (in segments) Sale of Stock, Number of Shares Issued in Transaction Number of shares sold Investment Type [Axis] Investment Type Net (accretion) amortization of investments in marketable debt securities (Accretion) Amortization Of Investments In Marketable Debt Securities (Accretion) amortization of investments in marketable debt securities. Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Unrecognized stock-based compensation expense Commercial Paper [Member] U.S. and foreign commercial paper Entity Address, Address Line One Entity Address, Address Line One Cash and Cash Equivalents, Fair Value Disclosure Cash equivalents Fair Value Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] Compensation expense: Antidilutive Securities [Axis] Antidilutive Securities Subsequent Event Type [Domain] Significant accounting policies. Significant Accounting Policies [Table] Significant Accounting Policies [Table] Income Statement Location [Axis] Income Statement Location Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Expected dividend yield Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net loss Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total Fair Value, Inputs, Level 2 [Member] Level 2 Collaborative Arrangement and Arrangement Other than Collaborative [Table] Depreciation, Depletion and Amortization Depreciation and amortization Depreciation, Depletion and Amortization, Total Contract with Customer, Liability, Noncurrent Deferred revenue Title of 12(b) Security Title of 12(b) Security Expected equity financing completion date Expected Equity Financing Completion Date Expected equity financing completion date. Investments [Domain] Investments Accounting Standards Update [Axis] Purchase Commitment, Remaining Minimum Amount Committed Potential milestone payment Net Cash Provided by (Used in) Investing Activities [Abstract] Cash flows from investing activities Subsequent Event [Table] Represent non cash rent expense. Noncash Rent Expense Non-cash rent expense Common stock subject to purchase under employee stock purchase program. Common Stock Subject To Purchase Under Employee Stock Purchase Program [Member] Common stock subject to purchase under ESPP Cash and Cash Equivalents [Axis] Cash and Cash Equivalents Potential proceeds from equity financing Potential Proceeds from Equity Financing Potential proceeds from equity financing. Common Stock, Shares, Outstanding Common stock, shares outstanding Common Stock, Shares, Outstanding, Beginning Balance Common Stock, Shares, Outstanding, Ending Balance Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Risk-free rate Stock-Based Compensation Share-Based Payment Arrangement [Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Schedule of Fair Value of Financial Assets Income Statement Location [Domain] Income Statement Location Cash and cash equivalent gross unrealized gain. Cash And Cash Equivalent Gross Unrealized Gain Gross Unrealized Gain Potential proceeds from collaboration extension fees Potential Proceeds from Collaboration Extension Fees Potential proceeds from collaboration extension fees. Document Type Document Type Net Cash Provided by (Used in) Investing Activities Net cash provided by investing activities Collaborative and License Arrangement Disclosure. Collaborative And License Arrangement Disclosure [Text Block] Collaboration Agreements Document Quarterly Report Document Quarterly Report Counterparty Name [Domain] Net Cash Provided by (Used in) Financing Activities Net cash provided by financing activities Entity Filer Category Entity Filer Category Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental non-cash investing and financing activities Balance Sheet Location [Domain] Balance Sheet Location Increase (Decrease) in Other Noncurrent Assets Other assets Option, License and Collaboration Agreement Option, License and Collaboration Agreement [Member] Option, license and collaboration agreement. Number of days volume considered for weighted average price to calculate premium Number of Days Volume Considered for Weighted Average Price to Calculate Premium Number of days volume considered for weighted average price to calculate premium. Accrued Liabilities, Current [Abstract] Accrued expenses: Nonoperating Income (Expense) Total other income The value of common stock authorized to issue in a public offering. Initial Public Offering Value Of Shares Authorized Initial public offering value of shares authorized Liabilities Total liabilities Available for sale debt securities accumulated gross unrealized loss before tax current. Available for Sale Debt Securities Accumulated Gross Unrealized Loss before Tax Current Gross Unrealized Loss, Short-term marketable securities Equity, Attributable to Parent Balance Balance Total stockholders' equity Gilead Equity Agreements Equity Agreements [Member] Equity agreements. Net Income (Loss) Net loss Net loss Net loss Nonoperating Income (Expense) [Abstract] Other income Proceeds from Issuance Initial Public Offering Net proceeds from the issuance of common stock through equity plans Schedule of Research and Development Arrangement, Contract to Perform for Others [Table] Schedule Of Research And Development Arrangement Contract To Perform For Others [Table] Accrued interest receivable Accured Interest Receivable Accured Interest Receivable Cash and Cash Equivalents [Domain] Cash and Cash Equivalents Corporate Debt Securities [Member] U.S and foreign corporate debt securities Statement of Financial Position [Abstract] Weighted Average Number of Shares Outstanding, Diluted Weighted average common shares outstanding, diluted Weighted Average Number of Shares Outstanding, Diluted, Total Weighted average common shares outstanding - diluted Use of Estimates, Policy [Policy Text Block] Use of Estimates Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Earnings Per Share, Basic and Diluted Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share Restructuring and related cost incurred cost benefit Restructuring And Related Cost Incurred Cost Benefit Restructuring charges Restructuring costs incurred Fair Value Hierarchy and NAV [Axis] Level 2 Measurement Frequency [Domain] Measurement Frequency Percentage of premium to weighted average price immediately prior to date of purchase Percentage of Premium to Weighted Average Price Immediately Prior to Date of Purchase Percentage of premium to weighted average price immediately prior to date of purchase. Payments to Acquire Property, Plant, and Equipment, Total Payments to Acquire Property, Plant, and Equipment Purchases of property and equipment Issuance of common stock under at-the-market (ATM) equity offering program, net of issuance costs (in shares) Stock Issued During Period, Shares, New Issues Employee-related Liabilities, Current Accrued compensation Employee-related Liabilities, Current, Total Lease expiration month and year Lease Expiration, Month And Year Lease expiration, month and year. Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Cash and cash equivalents at the end of the period Cash and cash equivalents at the beginning of the period Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations, Total