Cover [Abstract] Document Information [Table] Document Information [Line Items] Document Type Amendment Flag Entity Registrant Name Entity Central Index Key Entity Incorporation, State or Country Code Entity Address, Address Line One Entity Address, Address Line Two Entity Address, City or Town Entity Address, State or Province Entity Address, Postal Zip Code City Area Code Local Phone Number Entity Filer Category Entity Small Business Entity Emerging Growth Company Entity Ex Transition Period Entity Primary SIC Number Entity Tax Identification Number Contact Personnel Name Entity Address, Address Line Three Entity Addresses, Address Type [Axis] Address Type [Domain] Business Contact [Member] Statement of Financial Position [Abstract] Statement [Table] Statement [Line Items] Liabilities and Equity [Abstract] Liabilities, convertible preferred stock and stockholders' deficit Equity, Attributable to Parent [Abstract] Stockholders' deficit Common Stock, Value, Issued Common stock Additional Paid in Capital Additional paid-in capital Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Retained Earnings (Accumulated Deficit) Accumulated deficit Equity, Attributable to Parent Total stockholders' deficit Beginning balance Ending balance Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Current Accounts payable Accrued Expenses And Other Current Liabilities Accrued expenses and other current liabilities Total accrued expenses and other current liabilities Accrued expenses and other current liabilities. Operating Lease, Liability, Current Operating lease liabilities, current portion Liabilities, Current Total current liabilities Deferred Rent Credit, Current Deferred rent, current portion Liabilities and Equity Total liabilities, convertible preferred stock and stockholders' deficit Deferred Rent Credit, Noncurrent Deferred rent, net of current portion Other Liabilities, Noncurrent Other non-current liabilities Operating Lease, Liability, Noncurrent Operating lease liabilities, net of current portion Liabilities Total liabilities Commitments and Contingencies Commitments and contingencies Temporary Equity, Carrying Amount, Attributable to Parent Convertible preferred stock Ending balance Beginning balance Assets Total assets Other Assets, Noncurrent Other non-current assets Operating Lease, Right-of-Use Asset Operating lease right-of-use assets Operating lease right-of-use asset Operating lease right of use asset Advance Payments for Property and Equipment Advance payments for property and equipment Advance payments for property and equipment. Property, Plant and Equipment, Net Property and equipment, net Total property and equipment, net Assets, Current [Abstract] Current assets: Assets, Current Total current assets Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Short-Term Investments Short-term investments Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Class of Stock [Axis] Class of Stock [Domain] Series Seed Convertible Preferred Stock [Member] Series Seed Convertible Preferred Stock [Member] Series seed convertible preferred stock. Series A Convertible Preferred Stock [Member] Series A Convertible Preferred Stock [Member] Series A convertible preferred stock. Series B1 Convertible Preferred Stock [Member] Series B-1 Convertible Preferred Stock [Member] Series B-1 convertible preferred stock [Member] Series B1 convertible preferred stock Series B2 Convertible Preferred Stock [Member] Series B-2 Convertible Preferred Stock [Member] Series B-2 convertible preferred stock [Member] Series B2 convertible preferred stock. Common Stock, Shares, Outstanding Common stock, shares, outstanding Common Stock, Shares, Issued Common stock, shares, issued Common Stock, Shares Authorized Common stock shares authorized Common Stock, Par or Stated Value Per Share Common stock par or stated value per share Temporary Equity, Shares Authorized Temporary equity, shares authorized Temporary Equity, Shares Issued Temporary equity, shares issued Temporary Equity, Shares Outstanding Temporary equity, shares outstanding Beginning balance, shares Ending balance, shares Temporary Equity, Liquidation Preference Temporary equity, liquidation preference Temporary Equity, Par or Stated Value Per Share Temporary equity, par or stated value per share Income Statement [Abstract] Operating Expenses [Abstract] Operating expenses: Operating Expenses Total operating expenses Research and Development Expense Research and development General and Administrative Expense General and administrative Income Tax Expense (Benefit) Provision for income taxes Total provision for income taxes Net Income (Loss) Attributable to Parent Net loss Net loss Weighted Average Number of Shares Outstanding, Diluted Weighted-average common shares outstanding, diluted Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] Comprehensive loss: Nonoperating Income (Expense) [Abstract] Other income, net Change in Fair Value of Preferred Stock Tranche Liability Change in fair value of preferred stock tranche liability Change in fair value of preferred stock tranche liability Change in fair value of preferred stock tranche liability. Other Nonoperating Income Other income, net Nonoperating Income (Expense) Total other income, net Earnings Per Share, Basic Net loss per share, basic Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive loss Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Loss before provision for income taxes Other Comprehensive Income (Loss), Net of Tax [Abstract] Other comprehensive income (loss): OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Unrealized gain (loss) on available-for-sale investments Earnings Per Share, Diluted Net loss per share, diluted Weighted Average Number of Shares Outstanding, Basic Weighted-average common shares outstanding, basic Operating Income (Loss) Loss from operations Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Component [Domain] Preferred Stock [Member] Preferred Stock [Member] Common Stock [Member] Common Stock [Member] Additional Paid-In Capital [Member] AOCI Attributable to Parent [Member] Accumulated Other Comprehensive Loss [Member] Retained Earnings [Member] Accumulated Deficit [Member] Stock Issued During Period, Value, Stock Options Exercised Exercises of stock options Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Exercises of stock options, share Shares, Outstanding Beginning balance, shares Ending balance, shares Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Vesting of restricted common stock, share Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Vesting of restricted common stock Adjustments to Additional Paid in Capital, Warrant Issued Issuance of warrant to purchase common stock Stock Issued During Period, Value, Issued for Services Issuance of common stock for services rendered Reclassification of Preferred Stock Tranche Asset Upon Issuance of Convertible Preferred Stock Reclassification of preferred stock tranche asset upon issuance of Series A convertible preferred stock Reclassification of preferred stock tranche asset upon issuance of convertible preferred stock. APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Stock-based compensation expense Other Comprehensive Income (Loss), Net of Tax Other comprehensive income Stock Issued During Period, Shares, Issued for Services Issuance of common stock for services rendered, share Temporary Equity Stock Issued During Period Shares New Issues Convertible preferred stock, net of issuance costs, share Temporary equity stock issued during period shares new issues. Temporary Equity, Stock Issued During Period, Value, New Issues Convertible preferred stock, net of issuance costs Temporary Equity Stock Isssuance Costs Temporary equity stock isssuance costs Temporary equity stock isssuance costs. Statement of Cash Flows [Abstract] Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents Cash, cash equivalents and restricted cash, end of period Cash, cash equivalents and restricted cash, beginning of period Cash, cash equivalents and restricted cash Supplemental Cash Flow Information [Abstract] Supplemental cash flow information: Income Taxes Paid, Net, Total Cash paid for income taxes Operating Lease, Payments Cash paid for operating lease liabilities Net Cash Provided by (Used in) Investing Activities [Abstract] Investing Activities: Payments to Acquire Investments Purchases of investments Advance Payments for Property and Equipment Not Yet Received Advance payments for property and equipment not yet received Advance payments for property and equipment not yet received. Net Cash Provided by (Used in) Investing Activities Net cash provided by investing activities Payments to Acquire Property, Plant, and Equipment Purchases of property and equipment Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Proceeds from maturities of investments Proceeds from Sale of Property, Plant, and Equipment Proceeds from sale of property and equipment Net Cash Provided by (Used in) Financing Activities [Abstract] Financing Activities: Proceeds from Stock Options Exercised Proceeds from exercises of stock options Proceeds from (Payments for) Other Financing Activities Other financing activities, net Proceeds from Issuance of Redeemable Convertible Preferred Stock Convertible preferred stock, net of issuance costs Proceeds from redeemable convertible preferred stock Net Cash Provided by (Used in) Financing Activities Net cash provided by financing activities Net Cash Provided by (Used in) Operating Activities [Abstract] Operating Activities: 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: Depreciation Depreciation expense Non Cash Lease Expenses Non-cash lease expense Non cash lease expenses. Share-Based Payment Arrangement, Noncash Expense Stock-based compensation expense Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Other Noncurrent Assets and Liabilities, Net Other non-current assets and liabilities Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other current assets Increase (Decrease) in Other Noncurrent Assets Other non-current assets Increase (Decrease) in Deferred Charges Deferred rent Increase (Decrease) in Operating Lease Liability Operating lease liabilities Increase (Decrease) in Accrued Liabilities Accrued expenses Increase (Decrease) in Accounts Payable Accounts payable Gain (Loss) on Disposition of Property Plant Equipment Loss on disposal of property and equipment Accretion (Amortization) of Discounts and Premiums, Investments Net amortization of premiums and discounts on investments Non Cash Interest Expense Non-cash interest expense Non cash interest expense. Net Cash Provided by (Used in) Operating Activities Net cash used in operating activities Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Net increase (decrease) in cash, cash equivalents and restricted cash Noncash Investing and Financing Items [Abstract] Non-cash investing and financing activities: Property and Equipment Capitalized Under Tenant Improvement Allowance Property and equipment capitalized under tenant improvement allowance Property and equipment capitalized under tenant improvement allowance. Capital Expenditures Incurred but Not yet Paid Purchases of property and equipment in accounts payable and accrued expenses Financing Costs in Accounts Payable and Accrued Expenses Financing costs in accounts payable and accrued expenses Financing costs in accounts payable and accrued expenses. Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Operating lease liabilities arising from right-of-use assets Stock Option Exercise Receivables in Prepaid Expenses and Other Current Assets Stock option exercise receivables in prepaid expenses and other current assets Stock option exercise receivables in prepaid expenses and other current assets. Disclosure Of The Company And Liquidity [Abstract] Disclosure of the company and liquidity [abstract]. Disclosure Of The Company And Liquidity [Text Block] The Company and Liquidity Disclosure of the company and liquidity [text block]. Basis of Presentation and Significant Accounting Policies [Abstract] Basis of presentation and significant accounting policies [abstract]. Basis of Presentation and Significant Accounting Policies [Text Block] Basis of Presentation and Summary of Significant Accounting Policies Fair Value Disclosures [Abstract] Fair Value Disclosures [Text Block] Fair Value Measurements Investments, Debt and Equity Securities [Abstract] Investment [Text Block] Investments Cash and Cash Equivalents [Abstract] Cash and Cash Equivalents Disclosure [Text Block] Restricted Cash Property, Plant and Equipment [Abstract] Property, Plant and Equipment Disclosure [Text Block] Property and Equipment, Net Disclosure Of Accrued Expenses And Other Current Liabilities [Abstract] Disclosure of accrued expenses and other current liabilities [abstract]. Disclosure Of Accrued Expenses And Other Current Liabilities [Text Block] Accrued Expenses and Other Current Liabilities Disclosure of accrued expenses and other current liabilities [text block]. Debt Disclosure [Abstract] Debt Disclosure [Text Block] SVB Agreement Stockholders' Equity Note [Abstract] Equity [Text Block] Common Stock Temporary Equity Disclosure [Abstract] Disclosure In Entirety Of Temporary Equity [Text Block] Preferred Stock Disclosure In Entirety Of Temporary Equity [Text Block]. Share-Based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Text Block] Stock-based Compensation Lessee Disclosure [Abstract] Leases of Lessee Disclosure [Text Block] Leases Organization, Consolidation and Presentation of Financial Statements [Abstract] Collaborative Arrangement Disclosure [Text Block] Genevant Agreement Income Tax Disclosure [Abstract] Income Tax Disclosure [Text Block] Income Taxes Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Defined Contribution Plan [Abstract] Defined Contribution Plan [Text Block] 401(k) Savings Plan Related Party Transactions [Abstract] Related Party Transactions Disclosure [Text Block] Related Party Transactions Earnings Per Share [Abstract] Earnings Per Share [Text Block] Net Loss Per Share Subsequent Events [Abstract]