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Termination Date Trading Arrangement Termination Date Operating Lease, Expense, Term [Domain] Operating Lease, Expense, Term [Domain] Operating Lease, Expense, Term [Domain] Proceeds from maturities of marketable securities Proceeds from Sale and Maturity of Marketable Securities Accounts payable Increase (Decrease) in Accounts Payable Common stock, shares authorized (in shares) Common Stock, Shares Authorized Fair Value Debt Securities, Available-for-Sale 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] Gross Unrealized Gain Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Short-term Marketable Securities Short-Term Investments [Member] Adjustments to reconcile net loss to net cash used in operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] All Trading Arrangements All Trading Arrangements [Member] All Adjustments to Compensation All Adjustments to Compensation [Member] Award Timing Disclosures [Line Items] Performance of R&D services period Research And Development Service Performance Period Research and development service performance period. 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Equity [Abstract] Equity [Abstract] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Weighted average discount rate Operating Lease, Weighted Average Remaining Lease Term Related party revenue Revenue from Contract with Customer, Excluding Assessed Tax Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Amendment Flag Amendment Flag Money market funds Money market funds Money Market Funds [Member] Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Operating lease liability Operating Lease, Weighted Average Discount Rate, Percent Assets: Assets, Fair Value Disclosure [Abstract] Credit Facility [Domain] Credit Facility [Domain] Estimated useful life of asset (in years) Property, Plant and Equipment, Useful Life Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Leasehold improvements Leasehold Improvements [Member] Weighted average shares used to compute net loss per share, diluted (in shares) Weighted average number of shares used in computing net loss per share, diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Merck Original Agreement Merck Original Agreement [Member] Merck Original Agreement Cash and Cash Equivalents Cash and Cash Equivalents, Unrestricted Cash and Cash Equivalents, Policy [Policy Text Block] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Interest income, net Interest Income (Expense), Nonoperating, Net Operating expenses: Operating Expenses [Abstract] Company Selected Measure Amount Company Selected Measure Amount Additional paid-in capital Additional Paid in Capital, Common Stock Additional Paid-In Capital Additional Paid-in Capital [Member] Options expired (in dollars per shares) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Balance Sheet Location [Axis] Balance Sheet Location [Axis] Total assets Assets Name Awards Close in Time to MNPI Disclosures, Individual Name Cover [Abstract] Cover [Abstract] Subsequent Event Subsequent Events [Text Block] Stock-based compensation expense APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Fair Value Measurements, Recurring Fair Value, Recurring [Member] Restructuring and Related Activities [Abstract] Non-NEOs Non-NEOs [Member] Total undiscounted lease payments for the remainder of the year ending December 31, 2023 Lessee, Operating Lease, Liability, to be Paid Option repricing, shares eligible for future issuance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Plan Modification, Shares Eligible for Future Issuance Share-Based Compensation Arrangement by Share-Based Payment Award, Plan Modification, Shares Eligible for Future Issuance Transaction price for the two-year performance obligation Revenue, Remaining Performance Obligation, Amount Short-term marketable securities Short-Term Investments Construction-in-progress Construction in Progress [Member] Total operating expenses Operating Expenses Net decrease in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Reimbursable expense Research And Development Reimbursable Expense Research And Development Reimbursable Expense Non-PEO NEO Non-PEO NEO [Member] Operating lease option additional extend term Lessee, Operating Lease, Renewal Term Equity Component Equity Component [Domain] Adjustment to Compensation: Adjustment to Compensation [Axis] Purchases of property and equipment Payments to Acquire Machinery and Equipment Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Merck Amended Agreement Merck Amended Agreement [Member] Merck Amended Agreement Scenario [Axis] Scenario [Axis] Weighted average shares used to compute net loss per share, basic (in shares) Weighted average number of shares used in computing net loss per share, basic (in shares) Weighted Average Number of Shares Outstanding, Basic Entity Current Reporting Status Entity Current Reporting Status Concentration Risk Type Concentration Risk Type [Domain] Loss from operations Operating Income (Loss) Employees and Directors Employees And Directors [Member] Employees and directors. Concentration Risk Benchmark Concentration Risk Benchmark [Axis] Cash and cash equivalents Cash and Cash Equivalents [Member] Additional term Research And Development Option Extend Term Research and development option extend term. Collaborative Arrangement [Line Items] Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] Related Party Transaction [Axis] Related Party Transaction [Axis] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Statement [Line Items] Statement [Line Items] Property and Equipment, Net Property, Plant and Equipment, Policy [Policy Text Block] Vested and expected to vest (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Scenario [Domain] Scenario [Domain] Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Additional Disclosures [Abstract] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Type of Restructuring [Domain] Type of Restructuring [Domain]