Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] License And Collaboration Agreements [Line Items] License and Collaboration Agreements [Line Items] License and collaboration agreements. Weighted-average shares (Denominator): Weighted Average Number of Shares Outstanding, Diluted [Abstract] Trading Arrangement: Trading Arrangement [Axis] Maximum Maximum [Member] Statistical Measurement [Domain] Statistical Measurement [Domain] Title of 12(b) Security Title of 12(b) Security Debt Securities, Available-for-Sale [Table] Debt Securities, Available-for-Sale [Table] Document Fiscal Year Focus Document Fiscal Year Focus Adjustment to Compensation, Amount Adjustment to Compensation Amount Financial Instrument [Axis] Financial Instrument [Axis] Segment Reporting [Abstract] Common stock and additional paid-in capital: $0.0001 par value per share; 400.0 shares authorized; 127.0 shares in 2026 and 125.3 shares in 2025 issued and outstanding Common Stock, Value, Issued Accrued personnel expenses Employee-related Liabilities, Current Summary of Long-Term Debt Instruments Schedule of Long-Term Debt Instruments [Table Text Block] Over time Transferred over Time [Member] Restatement Determination Date Restatement Determination Date Debt Instrument, Tranche Type [Axis] Debt Instrument, Tranche Type [Axis] Debt Instrument, Tranche Type Summary of Prepaid and Other Current Assets Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block] Amendment Flag Amendment Flag Current liabilities: Liabilities, Current [Abstract] Other Other Sundry Liabilities, Current Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Gilead Collaboration Gilead Collaboration [Member] Gilead Collaboration Unrealized Loss Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Summary of Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Our Cash, Cash Equivalents and Marketable Securities Debt Securities, Available-for-Sale [Table Text Block] Leases [Abstract] Leases [Abstract] Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Related Party - Gilead Sciences, Inc. Related Party Transactions Disclosure [Text Block] Option payment upon completion of certain IND-enabling activities Option Payment Upon Completion Of certain IND-enabling Activities Option payment upon completion of certain IND-enabling activities. Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Entity Address, State or Province Entity Address, State or Province PEO Total Compensation Amount PEO Total Compensation Amount Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Shares used to compute net income (loss) per share, basic (in shares) Weighted Average Number of Shares Outstanding, Basic Receivable from collaboration partners Contract with Customer, Asset, after Allowance for Credit Loss, Current Amortization of discounts on marketable securities Accretion (Amortization) of Discounts and Premiums, Investments Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Accrued research and development Accrued Research And Development Expenses Current Accrued research and development expenses current. Collaborative Arrangement and Arrangement Other than Collaborative Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Number of board members Number Of Board Members Number Of Board Members Number of reportable segments Number of Reportable Segments Total current liabilities Liabilities, Current Entity Address, City or Town Entity Address, City or Town Option continuation payment due upon fourth anniversary of agreement Option Continuation Payment Due Upon Fourth Anniversary Of Agreement Option continuation payment due upon Fourth anniversary of agreement. Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Removal of option continuation payment under agreement Remove Option Continuation Payment Under Agreement Remove option continuation payment under agreement. Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Level 2 Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] STAR-221 Development Activities STAR-221 Development Activities [Member] STAR-221 Development Activities Other comprehensive loss Other Comprehensive Income (Loss), Net of Tax Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Proceeds from maturities of marketable securities Proceeds From Maturity Of Marketable Securities Proceeds from maturity of marketable securities. Early-stage development and preclinical programs Early Stage Development And Preclinical Programs Early Stage Development And Preclinical Programs Revenue Benchmark Revenue Benchmark [Member] License License [Member] Total upfront cash payment Total Upfront Cash Payment Total Upfront Cash Payment Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis Fair Value Assets And Liabilities Measured On Recurring Basis [Table Text Block] Fair value assets and liabilities measured on recurring basis. Restricted Cash, Noncurrent, Statement of Financial Position [Extensible Enumeration] Restricted Cash, Noncurrent, Statement of Financial Position [Extensible Enumeration] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Schedule of Long-Term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] STAR-121 Development Activities STAR-121 Development Activities [Member] STAR-121 Development Activities Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Deferred revenue (($48) and ($188) to a related party) Deferred revenue Increase (Decrease) in Contract with Customer, Liability Summary of Segment Reporting Information Segment Reporting [Table Text Block] AstraZeneca Agreement Astra Zeneca Agreement [Member] AstraZeneca Agreement. Outstanding (in shares) Weighted Average Number of Shares Issued, Basic Use of Estimates Use of Estimates, Policy [Policy Text Block] Rights to certain studies Rights To Certain Studies [Member] Rights To Certain Studies Related Party [Axis] Related and Nonrelated Parties [Axis] Other comprehensive loss Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Cash, Cash Equivalents and Marketable Securities [Abstract] Cash, Cash Equivalents and Marketable Securities [Abstract] Cash, cash equivalents and marketable securities. Adjusted for expense (income): Segment Reporting, Reconciliation [Abstract] Gilead Collaboration Agreement Option License And Collaboration Agreement [Member] Option, license and collaboration agreement. Long-term debt Total long-term debt Long-Term Debt Development services Development Services [Member] Development Services Document Period End Date Document Period End Date Changes in operating assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Access rights Access Rights [Member] Access Rights Option continuation payment due upon second anniversary of agreement Option Continuation Payment Due Upon Second Anniversary Of Agreement Option continuation payment due upon second anniversary of agreement. Net cash provided by investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Debt instrument, face amount Debt Instrument, Face Amount Receivable from collaboration partners ($— and $2 from a related party) Receivable from collaboration partners Increase (Decrease) in Contract with Customer, Asset Stockholders' Equity Equity [Text Block] Security Exchange Name Security Exchange Name Debt instrument, interest rate, effective percentage Debt Instrument, Interest Rate, Effective Percentage Taiho Pharmaceutical Co., Ltd Taiho Pharmaceutical Co Ltd [Member] Taiho Pharmaceutical Co., Ltd. Option continuation payment due upon sixth anniversary of agreement Option Continuation Payment Due Upon Sixth Anniversary Of Agreement Option continuation payment due upon Sixth anniversary of agreement. Additional clinical, regulatory and commercialization milestone payments Additional Clinical Regulatory And Commercialization Milestone Payments Additional clinical regulatory and commercialization milestone payments. Purchases of marketable securities Payments to Acquire Marketable Securities Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Current portion of lease liabilities Operating Lease, Liability, Current Number of programs, eligible to receive regulatory and commercial milestone payments Number Of Programs, Eligible To Receive Regulatory And Commercial Milestone Payments Number of programs, eligible to receive regulatory and commercial milestone payments. Net Loss Per Share Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Earnings Per Share [Abstract] Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Document Fiscal Period Focus Document Fiscal Period Focus Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Trading Symbol Trading Symbol Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Corporate securities and commercial paper Corporate Securities And Commercial Paper [Member] Corporate securities and commercial paper. Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] anti-PD-1 Anti P D One [Member] Anti PD one. Company Selected Measure Name Company Selected Measure Name Summary of Cash, Cash Equivalents and Restricted Cash Restrictions on Cash and Cash Equivalents [Table Text Block] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Upfront cash payment Upfront Cash Payment Upfront cash payment. Regulatory and commercial milestone payments received Regulatory And Commercial Milestone Payments Received Regulatory and commercial milestone payments received. Debt instrument, milestone achievement period Debt Instrument, Milestone Achievement Period Debt Instrument, Milestone Achievement Period Long-term debt (Contractual maturity 2030) Long-Term Debt, Gross Contract with customer, liability, cumulative catch-up adjustment to revenue, change in measure of progress and change in estimate of transaction price Contract With Customer, Liability, Cumulative Catch-up Adjustment To Revenue, Change In Measure Of Progress And Change In Estimate Of Transaction Price Contract With Customer, Liability, Cumulative Catch-up Adjustment To Revenue, Change In Measure Of Progress And Change In Estimate Of Transaction Price Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Summary of Fair Values of Our Cash, Cash Equivalents and Marketable Securities Cash, Cash Equivalent, and Investment [Table Text Block] Related Party Transactions [Abstract] Related Party Transactions [Abstract] Cash flows from operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Compensation Amount Outstanding Recovery Compensation Amount Individual: Individual [Axis] Shares used to compute net income (loss) per share, diluted (in shares) Weighted-average shares for diluted EPS (in shares) Weighted Average Number of Shares Outstanding, Diluted Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Tranche Two Tranche Two [Member] Tranche Two Underlying Security Market Price Change Underlying Security Market Price Change, Percent U.S. treasury securities US Treasury Securities [Member] Collaborative Arrangement and Arrangement Other than Collaborative Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Current and future programs exclusive access period Current And Future Programs Exclusive Access Period Current and future programs exclusive access period. Reimbursement from related party for shared costs Related Party Transaction Reimbursement From Related Party For Shared Costs Related party transaction reimbursement from related party for shared costs. Other assets Increase (Decrease) in Other Noncurrent Assets Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Cash paid for amounts included in measurement of lease liabilities Cash Paid For Amounts Included In Measurement Of Lease Liabilities Cash paid for amounts included in measurement of lease liabilities. Award Timing Predetermined Award Timing Predetermined [Flag] Clinical, regulatory and commercialization milestone payments Clinical Regulatory And Commercialization Milestone Payments Clinical regulatory and commercialization milestone payments. Debt Securities, Available-for-Sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Stock-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Level 1 Fair Value, Inputs, Level 1 [Member] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] License And Collaboration Agreements [Table] License and Collaboration Agreements [Table] License and collaboration agreements. Summary of Transaction Price and Allocation of Transaction Price to the Performance Obligations Schedule Of Transaction Price And Allocated To Transaction Price To Performance Obligations [Table Text Block] Schedule of transaction price and allocated to transaction price to performance obligations. Tranche One Tranche One [Member] Tranche One Effect of dilutive securities (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements All Executive Categories All Executive Categories [Member] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Additional clinical and regulatory milestone payments receivable Additional Clinical And Milestone Payments Received Under License Agreement Additional clinical and milestone payments received under license agreement. Number of research programs Number Of Research Programs Number of research programs. Plan Name [Domain] Plan Name [Domain] Antidilutive Securities Antidilutive Securities [Axis] R&D services R&D Services [Member] R&D Services Interest and other income, net Interest And Other Income Expense Nonoperating Net Interest and other income (expense) nonoperating net. Late-stage development programs Late Stage Development Programs Late Stage Development Programs Taiho Collaboration Agreement Taiho Collaboration Agreement [Member] Taiho Collaboration Agreement Concentration Risk Type [Domain] Concentration Risk Type [Domain] Summary of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Debt Disclosure [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Business Segment Segment Reporting [Text Block] Minimum Minimum [Member] Amended Gilead Collaboration Agreement Amended Gilead Collaboration Agreement [Member] Amended gilead collaboration agreement. Expiration Date Trading Arrangement Expiration Date Summary of Revenues by Collaboration, Category of Revenue and Method of Recognition Disaggregation of Revenue [Table Text Block] LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities [Abstract] Location, Statement of Income, Balance [Axis] Location, Statement of Income, Balance [Axis] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Other liabilities Other Liabilities Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Proceeds from issuance of common stock ($— and $14 from a related party) Proceeds from issuance of common stock Proceeds from Issuance of Common Stock Common stock, shares authorized (in shares) Common Stock, Shares Authorized Reportable segment Reportable Segment [Member] Reportable Segment Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Table] Antidilutive Security, Excluded EPS Calculation [Table] Sale of stock, number of shares issued in transaction (in shares) Sale of Stock, Number of Shares Issued in Transaction Exercise Price Award Exercise Price Cash flows from investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Related Party Transaction [Axis] Related Party Transaction [Axis] Segment Reporting [Line Items] Segment Reporting [Line Items] Document Quarterly Report Document Quarterly Report Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Segments [Domain] Segments [Domain] Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] Cash, cash equivalents and restricted cash at beginning of period Cash, cash equivalents and restricted cash at end of period Total cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation Common stock and additional paid-in capital Common Stock Including Additional Paid in Capital [Member] Unamortized discounts, issuance costs, charges and payment-in-kind interest, net Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Equity Component [Domain] Equity Component [Domain] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Other Other Services [Member] Other Services Secured Debt Secured Debt [Member] Sale of stock, consideration received on transaction Sale of Stock, Consideration Received on Transaction Adoption Date Trading Arrangement Adoption Date Milestone payments Milestone Payments Milestone payments. Counterparty Name [Domain] Counterparty Name [Domain] Total stockholders’ equity Beginning balance Ending balance Equity, Attributable to Parent Total non-operating income, net Nonoperating Income (Expense) Contingent milestone payments receivable Contingent Milestone Payments Receivable Contingent milestone payments receivable. ASSETS Assets [Abstract] Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost Accounting Policies [Abstract] Accounting Policies [Abstract] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Insider Trading Policies and Procedures [Line Items] Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Prepaid expenses and other current assets Total prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Condensed Consolidated Balance Sheet Components Supplemental Balance Sheet Disclosures [Text Block] Deposits for letters of credit Security Deposit WuXi Biologics License Agreement Wu Xi Biologics License Agreement [Member] WuXi Biologics license agreement. Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Antidilutive securities excluded from computation of diluted net loss per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Number of operating segments Number of Operating Segments Restricted stock units issued Restricted Stock Units (RSUs) [Member] Summary of Outstanding Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Entity Central Index Key Entity Central Index Key All Adjustments to Compensation All Adjustments to Compensation [Member] Access right and option continuation periods Access Rights And Option Continuation Periods [Member] Access Rights And Option Continuation Periods Other items, net Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Net cash used in operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Stockholders’ equity: Equity, Attributable to Parent [Abstract] Income Statement [Abstract] Income Statement [Abstract] Document Transition Report Document Transition Report Fair Value Hierarchy and NAV Fair Value Hierarchy and NAV [Axis] Non refundable and non creditable cash payments Non Refundable And Non Creditable Cash Payments Non refundable and non creditable cash payments. Operating expenses: Operating Expenses [Abstract] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] City Area Code City Area Code Accumulated other comprehensive loss AOCI Attributable to Parent [Member] All Individuals All Individuals [Member] Noncash lease expense Operating Lease, Right-of-Use Asset, Periodic Reduction Name Forgone Recovery, Individual Name Balance Sheet Related Disclosures [Abstract] Balance Sheet Related Disclosures [Abstract] Development milestone expense Milestone Expense Milestone expense. Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Statement [Line Items] Statement [Line Items] Total assets Assets Assets Entity [Domain] Entity [Domain] Number of exercise option to programs Number Of Exercise Option To Programs Number of exercise option to programs. Interest expense Interest income, net Interest Expense, Nonoperating Summary of Stock-Based Compensation Expense Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Unrealized Gain Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Option continuation payment receivable upon sixth anniversary of agreement Option Continuation Payment Receivable Upon Sixth Anniversary Of Agreement Option continuation payment receivable upon sixth anniversary of agreement. Stock-Based Compensation Share-Based Payment Arrangement [Text Block] Payment for option exercise Payment For Option Exercise Payment for option exercise. Collaboration term for current and future clinical programs Collaboration Term For Current And Future Clinical Programs Collaboration term for current and future clinical programs. Organization, Liquidity and Capital Resources Nature of Operations [Text Block] Issuance of common stock (in shares) Stock Issued During Period, Shares, New Issues PEO PEO [Member] Cash and investments Investments and Cash Total stock-based compensation Share-Based Payment Arrangement, Expense Other noncurrent liabilities Other Liabilities, Noncurrent Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Number of positions in securities in unrealized loss Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions Revenue recognized from amounts in deferred revenue at the beginning of the period Contract with Customer, Liability, Revenue Recognized Income taxes payable Taxes Payable, Current Accumulated deficit Retained Earnings [Member] Partnership reimbursements Partnership Reimbursements Partnership Reimbursements Total operating expenses Operating Expenses Money market funds Money Market Funds [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Common stock, shares outstanding (in shares) Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Outstanding Award Timing Disclosures [Line Items] Net income (loss) per share - diluted (in dollars per share) Earnings Per Share, Diluted Entity Current Reporting Status Entity Current Reporting Status Net cash provided by financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Total Shareholder Return Amount Total Shareholder Return Amount Credit related losses Financing Receivable, Credit Loss, Expense (Reversal) Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Research and development (Includes $2, $11, $2 and $6 from a related party) Research and Development Expense Adjustments to reconcile net loss to net cash used in operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Share-Based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] Total revenues from a customer Revenue from Contract with Customer, Excluding Assessed Tax Cash flows from financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Property and equipment, net Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization anti-CD39 Anti C D Thirty Nine [Member] Anti CD thirty nine. Financial Instruments [Domain] Financial Instruments [Domain] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Underlying Securities Award Underlying Securities Amount Debt instrument, face amount, contingently available Debt Instrument, Face Amount, Contingently Available Debt Instrument, Face Amount, Contingently Available Revenues Revenue from Contract with Customer [Text Block] Issuance of common stock Stock Issued During Period, Value, New Issues Proceeds from issuance of common stock pursuant to equity award plans Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Including Option Exercised Abmuno License Agreement Abmuno License Agreement [Member] Abmuno license agreement. Segment Reporting [Table] Segment Reporting [Table] Schedule Of Related Party Transactions By Related Party [Table] Related Party Transaction [Table] R&D Activities for Inflammation Programs Research And Development Activities For Inflammation Programs [Member] Research and development activities for inflammation programs member. Non-operating income (expense): Other Nonoperating Income (Expense) [Abstract] All Trading Arrangements All Trading Arrangements [Member] Proceeds from sales of marketable securities Proceeds From Sale Of Marketable Securities Proceeds from sale of marketable securities. Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Sale of stock, number of shares acquired in transaction (in shares) Sale Of Stock, Number Of Shares Acquired In Transaction Sale Of Stock, Number Of Shares Acquired In Transaction Loss from operations Operating Income (Loss) Total transaction price Revenue, Remaining Performance Obligation, Amount Current Fiscal Year End Date Current Fiscal Year End Date Proceeds from debt issuances, net Proceeds from Issuance of Debt Gilead Gilead Sciences Inc [Member] Gilead Sciences, Inc. Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Related Party Transaction [Domain] Related Party Transaction [Domain] Hercules Agreement Hercules Agreement [Member] Hercules Agreement Payment for option exercise Payment For Options Exercised Payment for option exercise. Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Entity File Number Entity File Number Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Common stock, shares issued (in shares) Common Stock, Shares, Issued Measure: Measure [Axis] Marketable securities Debt Securities, Available-for-Sale, Current Equity Components [Axis] Equity Components [Axis] Related Party Related Party [Member] Product and Service Product and Service [Domain] Class of Stock [Line Items] Class of Stock [Line Items] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Entity Interactive Data Current Entity Interactive Data Current Option period Option Period Option period. Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Casdatifan Collaboration Casdatifan Collaboration [Member] Casdatifan Collaboration Entity Small Business Entity Small Business Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent Termination Date Trading Arrangement Termination Date Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Other current liabilities Total other current liabilities Other Liabilities, Current Other noncurrent assets Other Assets, Noncurrent Document Type Document Type 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] Fair Value as of Grant Date Award Grant Date Fair Value Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Research and development expense, net of recoveries Research And Development Expense, Recoveries Research And Development Expense, Recoveries Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Arrangement Duration Trading Arrangement Duration Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Local Phone Number Local Phone Number Deferred revenue, noncurrent ($19 and $43 to a related party) Deferred revenue, noncurrent Contract with Customer, Liability, Noncurrent Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Income (loss) before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Commitments Commitments and Contingencies Total revenues Revenue Total revenues Revenues Percentage of outstanding common stock held Percentage Of Outstanding Common Stock Owned Percentage of outstanding common stock owned. Antidilutive Securities, Name Antidilutive Securities, Name [Domain] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Executive Category: Executive Category [Axis] Point in time Transferred at Point in Time [Member] Counterparty Name [Axis] Counterparty Name [Axis] All Award Types Award Type [Domain] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Fair Value Measurements Fair Value Disclosures [Text Block] Other collaboration Other collaboration Other Collaboration Revenue [Member] Other Collaboration Revenue [Member] Level 3 Fair Value, Inputs, Level 3 [Member] PRISM-1 Development Activities PRISM-1 Development Activities [Member] PRISM-1 Development Activities Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Total revenues from collaborations Revenue from Collaborative Arrangement, Excluding Revenue from Contract with Customer PEO Name PEO Name Equity Award Programs Equity Award Programs [Member] Equity Award Programs [Member] Contract with customer, liability Contract with Customer, Liability Cash, cash equivalents, and short-term investments Cash, Cash Equivalents, and Short-Term Investments Other segment items Segment Reporting, Other Segment Item, Amount Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Legal Entity [Axis] Legal Entity [Axis] Interest expense, debt Interest Expense, Debt Long-term marketable securities Debt Securities, Available-for-Sale, Noncurrent Accounts payable (($12) and $13 to a related party) Accounts payable Increase (Decrease) in Accounts Payable Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Non-NEOs Non-NEOs [Member] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Debt Instrument [Axis] Debt Instrument [Axis] Stock-based compensation expense Share-Based Payment Arrangement, Noncash Expense Compensation and personnel costs Labor and Related Expense Potential regulatory approval milestones payment receivable related to domvanalimab Potential Regulatory Approval Milestones Payment Receivable Related To Domvanalimab Potential regulatory approval milestones payment receivable related to domvanalimab. License and development services License And Development Services [Member] License And Development Services Purchase Agreement Common Stock Purchase Agreement [Member] Common stock purchase agreement. Employee stock purchase plan shares Employee Stock [Member] Leases Lessee, Operating Leases [Text Block] Long-Term Debt, Type [Domain] Long-Term Debt, Type [Domain] Net income (loss) per share - basic (in dollars per share) Earnings Per Share, Basic Deferred revenue ($11 and $35 to a related party) Deferred revenue, current Contract with Customer, Liability, Current Total current assets Assets, Current Statistical Measurement [Axis] Statistical Measurement [Axis] Insider Trading Arrangements [Line Items] Clinical regulatory milestone payments Clinical Regulatory Milestone Payments Clinical Regulatory Milestone Payments Award Type Award Type [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Accumulated deficit Retained Earnings (Accumulated Deficit) Product and Service Product and Service [Axis] Restricted cash (included in Other noncurrent assets) Restricted Cash, Noncurrent Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Proceeds from issuance of secured debt Proceeds from Issuance of Secured Debt Common stock Common Stock [Member] Fair Value Debt Securities, Available-for-Sale Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Cover [Abstract] Cover [Abstract] Percentage of revenues Concentration Risk, Percentage Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Equity Awards Adjustments Equity Awards Adjustments [Member] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] License and Collaborations Collaborative Arrangement Disclosure [Text Block] Total liabilities and stockholders’ equity Liabilities and Equity Total cash, cash equivalents and marketable securities Cash Cash Equivalents And Available For Sale Investments Cash, cash equivalents and available for sale investments. Employee Stock Option Share-Based Payment Arrangement, Option [Member] Alexander Azoy [Member] Alexander Azoy Segments [Axis] Segments [Axis] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Plan Name [Axis] Plan Name [Axis] Related Party [Domain] Related and Nonrelated Parties [Domain] Accrued interest receivable Interest Receivable, Current Tabular List, Table Tabular List [Table Text Block] Option continuation payment due upon eighth anniversary of agreement Option Continuation Payment Due Upon Eighth Anniversary Of Agreement Option continuation payment due upon Eighth anniversary of agreement. Other liabilities Increase (Decrease) in Other Noncurrent Liabilities Long-Term Debt Long-Term Debt [Text Block] Name Awards Close in Time to MNPI Disclosures, Individual Name Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] License And Collaboration Agreements [Abstract] License and Collaboration Agreements [Abstract] License and collaboration agreements. Summary of Other Current Liabilities Other Current Liabilities [Table Text Block] General and administrative (Includes $—, $2, $— and $2 from a related party) General and administrative expense General and Administrative Expense Sale of stock, price per share (in dollars per share) Sale of Stock, Price Per Share Debt Instrument, Tranche Type [Domain] Debt Instrument, Tranche Type [Domain] Debt Instrument, Tranche Type [Domain] Adjustment to Compensation: Adjustment to Compensation [Axis] Option payment upon achievement of certain development milestones Option Payment Upon Achievement Of Certain Development Milestones Option payment upon achievement of certain development milestones. Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Summary of Cash and Non-cash Information Related to Operating Leases Schedule Of Supplemental Cash Flow Disclosures And Non-Cash Financing Activities Related To Operating Leases [Table Text Block] Schedule of supplemental cash flow disclosures and non-cash financing activities related to operating leases. Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Total assets measured at fair value Assets, Fair Value Disclosure Name Measure Name Income Taxes Income Tax Disclosure [Text Block] Accounts payable ($12 and $24 to a related party) Accounts payable, current Accounts Payable, Current Pay vs Performance Disclosure [Line Items] Fair Value Hierarchy and NAV Fair Value Hierarchy and NAV [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] Taiho Agreement Option And License Agreement [Member] Option and license agreement. Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Entity Filer Category Entity Filer Category Name Trading Arrangement, Individual Name Cash and cash equivalents Cash and Cash Equivalent Debt instrument, additional committed amount Debt Instrument, Additional Committed Amount Debt Instrument, Additional Committed Amount Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Company Selected Measure Amount Company Selected Measure Amount Option fee per program for all other programs entering clinical development to exercise option Option Fee Per Program For All Other Programs Entering Clinical Development To Exercise Option Option fee per program for all other programs entering clinical development to exercise option. Depreciation and amortization Depreciation, Depletion and Amortization Schedule of Stock by Class [Table] Stock, Class of Stock [Table] Net loss Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Current assets: Assets, Current [Abstract] Non-PEO NEO Non-PEO NEO [Member] Entity Address, Address Line One Entity Address, Address Line One Income tax expense Income Tax Expense (Benefit) Customer Concentration Risk Customer Concentration Risk [Member] Award Timing Method Award Timing Method [Text Block] Consolidation Consolidation, Policy [Policy Text Block] Net increase (decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Cash, Cash Equivalents and Marketable Securities Cash, Cash Equivalent, and Marketable Security [Text Block] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Net income (loss) (Numerator): Net Income (Loss) Attributable to Parent [Abstract] Development cost recorded within research and development expenses Research and Development Expense (Excluding Acquired in Process Cost) Royalties payable term Royalties Payable Term Royalties Payable Term Reimbursement of research and development expense Reimbursement Of Research And Development Expense Reimbursement of research and development expense Net income (loss) Net income (loss) Net Income (Loss) Attributable to Parent Long-Term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Statement [Table] Statement [Table] Prepaid expenses and other assets Prepaid Expenses And Other Current Assets Prepaid expenses and other current assets. Taiho Collaboration Taiho Collaboration [Member] Taiho Collaboration Restatement Determination Date: Restatement Determination Date [Axis] Certificate of deposit Certificates of Deposit [Member] Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table] Deferred revenue, non-refundable payment Deferred Revenue, Non-Refundable Payment Deferred Revenue, Non-Refundable Payment Summary of Revenue Recognized as a Result of Changes in Deferred Revenue Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Option payments received Option Payment Received Option payment received. Common stock options issued and outstanding Share-Based Payment Arrangement [Member] Revenues: Revenues [Abstract] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block]