Document and Entity Information Document Information [Table] Document Information [Line Items] Document Type Document Period End Date Entity Registrant Name Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Interactive Data Current Entity Filer Category Entity Small Business Entity Emerging Growth Company Entity Ex Transition Period Entity Shell Company Entity Public Float Entity Common Stock, Shares Outstanding Entity Central Index Key Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Period Focus Amendment Flag CONSOLIDATED BALANCE SHEETS Statement [Table] Statement [Line Items] Statement Assets [Abstract] Assets Current assets: Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Short-term Investments Investments Amount of asset related to consideration paid in advance and other for costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer. Prepaid Expense And Other, Current Prepaid expenses and other current assets Restricted Cash, Current Restricted cash Restricted cash (current) Assets, Current Total current assets Operating Lease, Right-of-Use Asset Operating lease, right-of-use-asset Property, Plant and Equipment, Net Property, plant and equipment, net Property, plant and equipment, net Restricted Cash, Noncurrent Restricted cash Restricted cash (non-current) Other Assets, Noncurrent Other assets Assets Total assets Liabilities and Equity [Abstract] Liabilities and Stockholders' Equity Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Current Accounts payable Carrying value as of the balance sheet date of obligations incurred and payable, excluding current operating lease liabilities, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accrued Expenses And Other Current Liabilities Excluding Current Operating Lease Liabilities Accrued expenses and other current liabilities Accrued expenses and other current liabilities Accrued expenses and other current liabilities Operating Lease, Liability, Current Operating lease liabilities Operating lease liabilities, current portion Liabilities, Current Total current liabilities Long-term Debt, Excluding Current Maturities Long-term debt, net of discount Long‑term debt, net of current portion Other Liabilities, Noncurrent Other long-term liabilities Operating Lease, Liability, Noncurrent Operating lease liabilities, net of current portion Capital Lease Obligations, Noncurrent Lease financing obligation Liabilities Total liabilities Commitments and Contingencies. Commitments and contingencies (see Note 12) Stockholders' Equity Attributable to Parent [Abstract] Stockholders' equity: Preferred Stock, Value, Issued Preferred stock, $0.001 par value; 10,000,000 shares authorized at December 31, 2019 and December 31, 2018; no shares issued or outstanding at December 31, 2019 and December 31, 2018 Common Stock, Value, Issued Common stock, $0.001 par value; 150,000,000 shares authorized at December 31, 2019 and December 31, 2018; 80,016,245 and 79,234,853 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively Additional Paid in Capital Additional paid-in capital Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income (loss) Retained Earnings (Accumulated Deficit) Accumulated deficit Stockholders' Equity Attributable to Parent Balances at End of period Balances at Beginning of period Total stockholders' equity Stockholders Equity Liabilities and Equity Total liabilities and stockholders' equity Preferred Stock, Par or Stated Value Per Share Preferred stock, par value (in dollars per share) Preferred Stock, Shares Authorized Preferred stock, share authorized (in shares) Preferred Stock, Shares Issued Preferred stock, shares issued (in shares) Preferred Stock, Shares Outstanding Preferred stock, shares outstanding (in shares) Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Common Stock, Shares Authorized Common stock, share authorized (in shares) Common stock, authorized (in shares) Common Stock, Shares, Issued Common stock, shares issued (in shares) Common Stock, Shares, Outstanding Common stock, shares outstanding (in shares) CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS Operating Expenses [Abstract] Operating expenses: Research and Development Expense Research and development General and Administrative Expense General and administrative Operating Expenses Total operating expenses Total operating expenses Operating Income (Loss) Loss from operations Loss from operations Nonoperating Income (Expense) [Abstract] Other income (expense): Investment Income, Interest Interest income Interest Expense Interest expense Fair Value Adjustment of Warrants Change in fair value of preferred stock warrant liability Change in fair value of preferred stock warrant liability Other Nonoperating Income (Expense) Other income (expense), net Nonoperating Income (Expense) Total other income (expense), net Net Income (Loss) Attributable to Parent Net Loss Net loss Net loss Temporary Equity, Accretion to Redemption Value, Adjustment Accretion of Series A redeemable convertible preferred stock to redemption value Net Income (Loss) Available to Common Stockholders, Basic Net loss attributable to common stockholders Earnings Per Share, Basic and Diluted Net loss per share attributable to common stockholders, basic and diluted Net loss per share, basic and diluted Weighted Average Number of Shares Outstanding, Basic and Diluted Weighted average common shares outstanding, basic and diluted Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Comprehensive loss: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other comprehensive income (loss): Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Unrealized gains (losses) on investments, net of tax of $0 Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive loss Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Unrealized gains (losses) on investments, tax Statement of Stockholders' Equity [Abstract] Shares, Outstanding Balances at End of period (in shares) Balances at Beginning of period (in shares) Stock Issued During Period, Shares, New Issues Shares issued (in shares) Shares issued Stock Issued During Period, Value, New Issues Issuance of common stock, initial public offering, net of issuance cost $3,548 Number of common stock shares issued as part of cashless exercise of warrants. Class of Warrant or Right, Exercise of Warrants, Number of Common Stock Shares Issued Cashless exercise of warrants Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Exercised Issuance of common stock upon exercise of stock options (in shares) Stock Issued During Period, Value, Stock Options Exercised Issuance of common stock upon exercise of stock options Number of shares issued during period one time bonus payment. Stock Issued During Period Shares, One Time Bonus Payment Issuance of common stock for one‑time bonus payment (in shares) Number of shares issued during period restricted common stock exercise of stock options. Stock Issued During Period Shares, Restricted Common Stock Exercise of Stock Options Issuance of restricted common stock upon early exercise of stock options (in shares) The amount of stock issued during period restricted common stock exercise of stock options. Stock Issued During Period Value, Restricted Common Stock Exercise of Stock Options Issuance of restricted common stock upon early exercise of stock options Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Issuance of restricted common stock (in shares) Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Issuance of restricted common stock Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Stock-based compensation expense Stock Repurchased During Period, Shares Repurchase of unvested restricted common stock (in shares) Stock Repurchased During Period, Value Repurchase of unvested restricted common stock Adjustments to Additional Paid in Capital, Share-based Compensation, Restricted Stock Unit or Restricted Stock Award, Requisite Service Period Recognition Vesting of restricted common stock Amount of increase in additional paid-in capital due to conversion of preferred stock warrants to common stock warrants. Adjustment to Additional Paid in Capital Conversion of Preferred Stock Warrant to Common Stock Warrant Conversion of preferred stock warrant to common stock warrant upon closing of initial public offering Number of common stock issued on conversion Issuance of warrants exercise Conversion of redeemable convertible preferred stock to common stock (in shares) Stock Issued During Period, Value, Conversion of Convertible Securities Conversion of redeemable convertible preferred stock to common stock Cumulative Effect of New Accounting Principle in Period of Adoption Change in fair value of the unvested awards Cumulative effect adjustment for adoption Unrealized Gain (Loss) on Investments Unrealized gains (losses) on investments Preferred Stock, Accretion of Redemption Discount Accretion of Series A redeemable convertible preferred stock to redemption value Temporary Equity [Abstract] Convertible preferred stock Temporary Equity, Shares Outstanding Balances at End of period (in shares) Balances at Beginning of period (in shares) Preferred stock outstanding Temporary Equity, Carrying Amount, Attributable to Parent Balances at End of period Balances at Beginning of period Number of shares temporary equity issued during period new issues. Temporary equity Stock issued during period Shares New Issues Issuance of stock, net of issuance costs (in shares) Temporary Equity, Stock Issued During Period, Value, New Issues Issuance of stock, net of issuance costs Conversion of Stock, Shares Converted Conversion of redeemable convertible preferred stock to common stock (in shares) Conversion of Stock, Amount Converted Conversion of redeemable convertible preferred stock to common stock Temporary Equity, Accretion to Redemption Value Accretion of Series A redeemable convertible preferred stock to redemption value Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Net of issuance cost CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS Cash flows from operating activities: Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net loss 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: Share-based Compensation Stock-based compensation expense Depreciation, Depletion and Amortization Depreciation and amortization expense Investment Income, Amortization of Discount Accretion of discount on investments Gain (Loss) on Disposition of Property Plant Equipment Loss on disposal of property and equipment Non-Cash Interest Expenses Non-cash interest expense Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other current assets The increase (decrease) during the reporting period in the value of operating lease, right-of-use-asset. Increase Decrease, Operating Lease, Right Of Use Asset Operating lease, right-of-use-asset Other assets Other assets Increase (Decrease) in Accounts Payable Accounts payable The increase (decrease) during the reporting period in the amounts of accrued expenses and other current liabilities. Increase (Decrease) in Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities The increase (decrease) during the reporting period in deferred rent. Increase (Decrease) in Deferred Rent Deferred rent The increase (decrease) during the reporting period in the value of operating lease liabilities. Increase Decrease, Operating Lease Liabilities Operating lease liabilities Net Cash Provided by (Used in) Operating Activities Net cash used in operating activities Net Cash Provided by (Used in) Investing Activities [Abstract] Cash flows from investing activities: Payments to Acquire Property, Plant, and Equipment Purchases of property, plant and equipment Payments to Acquire Investments Purchases of investments Proceeds from Sale, Maturity and Collection of Investments Sales and maturities of investments Net Cash Provided by (Used in) Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Cash flows from financing activities: Proceeds from Issuance of Convertible Preferred Stock Proceeds from issuance of convertible preferred stock, net of issuance costs Proceeds from issuance of convertible preferred stock Proceeds from Issuance Initial Public Offering Net proceeds after deducting underwriting discounts and commissions and other offering costs Proceeds from initial public offering of common stock, net of commissions and underwriting discounts Payments of Stock Issuance Costs Payments of initial public offering costs Payments of initial public offering costs Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Excluding Stock Options Proceeds from the sale of restricted common stock Proceeds from (Repayments of) Notes Payable Proceeds from repayment of promissory note Payments of Debt Issuance Costs Payments of debt issuance costs Payments for Repurchase of Common Stock Repurchase of unvested restricted common stock Proceeds from (Repayments of) Secured Debt Proceeds from borrowings under loan and security agreement Repayments of Debt Payment of long-term debt Repayment Proceeds from Stock Options Exercised Proceeds from issuance of common stock upon exercise of stock options Net Cash Provided by (Used in) Financing Activities Net cash provided by financing 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 Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period Cash, cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents and Restricted Cash Supplemental Cash Flow Information [Abstract] Supplemental cash flow information: Interest Paid, Excluding Capitalized Interest, Operating Activities Cash paid for interest, net of interest capitalized Operating Lease, Payments Cash paid for leases Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental disclosure of non-cash investing and financing information: Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Lease assets obtained in exchange for new operating lease liabilities Capital Expenditures Incurred but Not yet Paid Purchases of property, plant and equipment included in accounts payable or accrued expenses The amount of non-cash investing transactions capitalized under build to suit transactions. Capitalization Of Build To Suit Lease Transaction Amounts capitalized under build-to-suit transaction Amount of cash inflow from exercise of option in other current assets under share-based payment arrangement. Proceeds From Stock Options Exercised In Other Current Assets Proceeds from issuance of common stock upon exercise of stock options in other current assets Amount of warrants reclassified to additional paid in capital in noncash investing and financing activities. Reclassification of Warrants to Additional Paid In Capital Reclassification of warrant liability to additional paid-in capital Conversion of preferred stock to common stock upon closing of the initial public offering. Conversion of Preferred Stock to Common Stock Upon Initial Public Offering Conversion of preferred stock to common stock upon closing of the initial public offering The amount of non cash transaction on issuance of preferred stock warrant for loan and security agreement. Preferred Stock Warrant Issuance For Loan and Security Agreement Issuance of preferred stock warrant in connection with loan and security agreement The amount non cash on accretion of redeemable convertible preferred stock to redemption value. Accretion Of Redeemable Convertible Preferred Stock To Redemption Value Accretion of Series A redeemable convertible preferred stock to redemption value The amount of debt issuance costs included in accounts payable and accrued expenses. Debt Issuance Costs Included In Accounts Payable And Accrued Expenses Debt issuance costs included in accounts payable and accrued expenses Nature of the Business and Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Nature of the Business and Basis of Presentation Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Investments and Fair Value of Financial Assets and Liabilities Fair Value Disclosures [Text Block] Investments and Fair Value of Financial Assets and Liabilities Property, Plant and Equipment, Net. Property, Plant and Equipment Disclosure [Text Block] Property, Plant and Equipment, Net Accrued Expenses and Other Current Liabilities Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] Accrued Expenses and Other Current Liabilities Debt Debt Disclosure [Text Block] Debt Convertible Preferred Stock. The entire disclosure for terms, amounts, nature of changes, rights and privileges, dividends, and other matters related to convertible preferred stock. Temporary Equity [Text Block] Convertible Preferred Stock Warrants to Purchase Convertible Preferred Stock. The entire disclosure of warrants to purchase convertible preferred stock. Warrants to Purchase Convertible Preferred Stock Disclosure [Text block] Warrants to Purchase Convertible Preferred Stock Equity Stockholders' Equity Note Disclosure [Text Block] Equity Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Stock-Based Compensation Income Taxes Income Tax Disclosure [Text Block] Income Taxes Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Leases Lessee, Operating Leases [Text Block] Leases Net Loss Per Share Earnings Per Share [Text Block] Net Loss Per Share Related Parties