Not available. [DocumentAndEntityInformationAbstract] Statement [Table] Statement [Line Items] Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Current Reporting Status Entity Filer Category Document Fiscal Year Focus Document Fiscal Period Focus Entity Small Business Entity Emerging Growth Company Entity Ex Transition Period Entity Shell Company Entity Common Stock, Shares Outstanding CONDENSED BALANCE SHEETS Assets [Abstract] Assets Assets, Current [Abstract] Current assets: Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Cash and cash equivalents Restricted Cash, Current Restricted cash Prepaid Expense and Other Assets, Current Prepaid expenses and other current assets Assets, Current Total current assets Property, Plant and Equipment, Net Property and equipment, net Property and equipment, net Other Assets, Noncurrent Other assets Assets Total assets Liabilities and Equity [Abstract] Liabilities, Preferred Stock and Stockholders’ Equity (Deficit) Liabilities, Current [Abstract] Current liabilities: Accounts Payable, Current Accounts payable Accrued Liabilities, Current Accrued liabilities Deferred Rent Credit, Current Deferred rent, current portion Long-term Debt, Current Maturities Less: current portion of term loan Term loan, current portion Amount of deferred income from related party transactions excluding obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as current. Related Party Transactions, Deferred Revenue, Current Deferred revenue, current portion Deferred revenue, current portion Liabilities, Current Total current liabilities Deferred Rent Credit, Noncurrent Deferred rent, net of current portion Long-term Debt, Excluding Current Maturities Term loan, net of current portion Amount of deferred income from related party transactions excluding obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as noncurrent. Related Party Transactions, Deferred Revenue, Noncurrent Deferred revenue, net of current portion Deferred revenue, non-current portion Liabilities Total liabilities Commitments and Contingencies. Commitments and contingencies (Note 6) Not available. Preferred Stock Abstract Redeemable preferred stock: Temporary Equity, Carrying Amount, Attributable to Parent Balance at the end Balance at the beginning Total redeemable preferred stock Stockholders' Equity Attributable to Parent [Abstract] Stockholders’ equity (deficit): Preferred Stock, Value, Issued Preferred stock; par value of $0.001 per share, 10,000,000 and 0 shares authorized at June 30, 2019 and December 31, 2018. No shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively Common Stock, Value, Issued Common stock, par value of $0.001 per share; 100,000,000 and 158,745,671 shares authorized at June 30, 2019 and December 31, 2018, respectively, 22,714,765 and 1,374,812 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively Additional Paid in Capital Additional paid-in capital Retained Earnings (Accumulated Deficit) Accumulated deficit Stockholders' Equity Attributable to Parent Balance at the end Balance at the beginning Total stockholders’ equity (deficit) Liabilities and Equity Total liabilities, preferred stock and stockholders’ equity (deficit) Preferred Stock, Par or Stated Value Per Share Preferred stock, par value per share Preferred Stock, Shares Authorized Preferred stock, number of shares authorized Preferred Stock, Shares Issued Preferred stock, shares issued Preferred Stock, Shares Outstanding Preferred stock, shares outstanding Common Stock, Par or Stated Value Per Share Common stock, par value per share Common Stock, Shares Authorized Common stock, number of shares authorized Common Stock, Shares, Issued Common stock, shares issued Common Stock, Shares, Outstanding Balance at the end (in shares) Balance at the beginning (in shares) Common stock, shares outstanding CONDENSED STATEMENTS OF OPERATIONS Revenue from Contract with Customer [Abstract] Revenue: Revenue from Contract with Customer, Excluding Assessed Tax Revenue Type of Revenue [Extensible List] Operating Expenses [Abstract] Operating expenses: Research and Development Expense Research and development General and Administrative Expense General and administrative Operating Expenses Total operating expenses Operating Income (Loss) Loss from operations Other Nonoperating Income (Expense) Other income, net Net Income (Loss) Attributable to Parent Net loss Net loss Earnings Per Share, Basic and Diluted Net loss per share attributable to common stockholders—basic and diluted (in dollars per share) Weighted Average Number of Shares Outstanding, Basic and Diluted Weighted average common shares outstanding—basic and diluted (in shares) CONDENSED STATEMENTS OF PREFERRED STOCK AND STOCKHOLDERS’ DEFICIT Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Deficit Temporary Equity, Shares Outstanding Balance at the end (in shares) Balance at the beginning (in shares) Equity impact of the value of new stock issued during the period. Stock Issued During Period Value Initial Public Offering Initial public offering, net of issuance costs of $9.4 million Number of new stock issued during the period from initial public offering. Stock Issued During Period Shares Initial Public Offering Initial public offering, net of issuance costs of $9.4 million (in shares) Stock Issued During Period, Value, Conversion of Units Conversion of preferred stock to common stock Stock Issued During Period, Shares, Conversion of Units Conversion of preferred stock to common stock (in shares) Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Stock based compensation Stock Issued During Period, Value, New Issues Issuance of stock Stock Issued During Period, Shares, New Issues Issuance of stock (in shares) Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Initial public offering issuance costs CONDENSED STATEMENTS OF CASH FLOWS Net Cash Provided by (Used in) Operating Activities [Abstract] 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 provided by (used) in operating activities: Depreciation, Depletion and Amortization Depreciation and amortization expense Depreciation and amortization Share-based Compensation Stock-based compensation Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other assets Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accrued Liabilities Accrued liabilities and other current liabilities Amount of increase (decrease) in deferred income from related party and obligation to transfer product and service to customer for which consideration has been received or is receivable. Increase (Decrease) in Deferred Revenue From Related Party Deferred revenue 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 Purchase of property and equipment 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 Initial Public Offering Proceeds from issuance of shares, net Proceeds from initial public offering, net of issuance costs Proceeds from Issuance of Preferred Stock and Preference Stock Proceeds from issuance of preferred stock, net of issuance costs Equity investment Proceeds from Issuance of Common Stock Proceeds from issuance of common stock Proceeds from Issuance of Debt Proceeds from the term loan Repayments of Debt Payments of the term loan 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 in cash, cash equivalents and restricted cash 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 year Total Supplemental Cash Flow Information [Abstract] Supplemental disclosures of cash flow information: Interest Paid, Excluding Capitalized Interest, Operating Activities Cash paid for interest Noncash Investing and Financing Items [Abstract] Supplemental disclosures of noncash investing and financing activities: Capital Expenditures Incurred but Not yet Paid Purchase of property and equipment included in accrued liabilities Debt Issuance Costs Incurred During Noncash or Partial Noncash Transaction Deferred financing costs in accrued liabilities Represents the noncash conversion of convertible preferred stock into common stock. Noncash Or Part Noncash Conversion of Convertible Preferred Stock Into Common Stock Conversion of convertible preferred stock into common stock Nature of the Business Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Nature of the Business Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Fair Value of Financial Instruments Property and Equipment, Net Property, Plant and Equipment Disclosure [Text Block] Property and Equipment, Net N/A Agreement with Eli Lilly and Company Collaborative Arrangement Disclosure [Text Block] Agreement with Eli Lilly and Company Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Term Loan Debt Disclosure [Text Block] Term Loan 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 Subsequent Events Subsequent Events [Text Block] Subsequent Events Basis of Accounting, Policy [Policy Text Block] Basis of Presentation Use of Estimates, Policy [Policy Text Block] Use of Estimates Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Cash Revenue from Contract with Customer [Policy Text Block] Revenue Recognition Disclosure of accounting policy pertaining to new accounting pronouncement that has been issued but not yet adopted. Description of New Accounting Pronouncements Not yet Adopted [Policy Text Block] Recently Issued Accounting Pronouncements Cash, Cash Equivalents and Investments [Table Text Block] Summary of reconciliation cash and cash equivalents and restricted cash per the balance sheet to the statement of cash flows Fair Value, by Balance Sheet Grouping [Table Text Block] Summary of fair value of the Company’s financial assets Property, Plant and Equipment [Table Text Block] Summary of property and equipment Represents the tabular disclosure of deferred revenue from related party. Schedule of Deferred Revenue From Related Party [Table Text Block] Summary of deferred revenue included in the Company’s balance sheets Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of future minimum payments Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of future maturities Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of stock option activity Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Summary of stock based compensation expense recorded Subsequent Event [Table] Subsequent Event [Line Items] Subsequent Event Nature of the Business Stockholders' Equity Note, Stock Split, Conversion Ratio Reverse stock split ratio Share Price Share price The cash outflow for payment of underwriting discounts and commissions. Payments Of Underwriting Discounts And Commissions Underwriting discounts and commissions Payments of Stock Issuance Costs Offering expenses Restricted Cash Amount of required reserve of restricted cash. Required Reserve Restricted Cash Current Restricted cash required reserve Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Reconciliation of cash and cash equivalents and restricted cash per the balance sheet to the statement of cash flows Represents restricted cash and other assets current. Restricted Cash And Other Assets Current Restricted cash (including $4,200 in other assets at June 30, 2019) Fair Value, by Balance Sheet Grouping [Table] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Fair value of the Company’s financial assets Cash and Cash Equivalents, Fair Value Disclosure Money market funds (cash equivalents) Fair Value, Assets, Level 1 to Level 2 Transfers, Amount Assets transferred from level 1 to level 2 Fair Value, Assets, Level 2 to Level 1 Transfers, Amount Assets transferred from level 2 to level 1 Property, Plant and Equipment [Table] Property, Plant and Equipment [Line Items] Property, Plant and Equipment, Net [Abstract] Property and Equipment, Net Property, Plant and Equipment, Gross Property and equipment, gross Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less: accumulated depreciation and amortization Schedule of Collaborative Arrangements and Non-collaborative Arrangement Transactions [Table] Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Collaborative Arrangements Represents the period of expiry from date of agreement under collaborative arrangement. Collaborative Arrangement Period of Expiry from Date of Agreement Period of expiry from date of agreement Represents the amount of upfront non-refundable payment received under collaborative arrangement. Collaborative Arrangement Upfront Non-refundable Payment Received Upfront non-refundable payment received Represents the maximum amount of development and regulatory milestones and sales milestones receivable. Collaborative Arrangement Maximum Development Regulatory and Sales Milestone Receivable Maximum development and regulatory milestones and sales milestone receivable Represents the maximum amount of development and regulatory milestones and sales milestones payable upon option exercise. Collaborative Arrangement Maximum Development Regulatory and Sales Milestone Payable Upon Option Exercise Maximum development and regulatory milestones and sales milestone payable upon option exercise The number of performance obligations. Revenue Recognition Number Of Performance Obligations The number of performance obligations. The amount of transaction fees under the agreement. Collaboration Agreement, Transaction Price Transaction price Change in Contract with Customer, Liability [Abstract] Deferred revenue Amount of deferred income from related party transactions. Related Party Transactions, Deferred Revenue Total deferred revenue from related party, end of period Deferred revenue from related party, beginning of period Amount of increase (decrease) in deferred income from related party transactions attributable to upfront payment. Related Party Transactions, Deferred Revenue, Up-front Payment Up-front payment Amount of increase (decrease) in deferred income from related party transactions attributable to premium on the proceeds from investment. Related Party Transactions, Deferred Revenue, Attributed Premium on Proceeds From Investment Attributed premium on the proceeds from Lilly’s investment in the Company Amount of increase (decrease) in deferred income from related party transactions attributable to research and development support payment. Related Party Transactions, Deferred Revenue, Research And Development Support Payment Research and development support billing Amount of increase (decrease) in deferred income from related party transactions attributable to collaboration revenue recognized. Related Party Transactions, Deferred Revenue, Collaboration Revenue Recognized Revenue from research and development arrangement recognized Period for which the base rent is abated. Period For Which Base Rent Is Abated Period for which base rent is abated The amount of annual base rent per month after abatement. Annual Base Rent Per Month After Abatement Annual base rent per month after abatement The percentage of annual increase in operating lease rent. Percentage Of Annual Increase In Lease Rent Percentage of annual increase in lease rent The carrying value as of the balance sheet date of the current and noncurrent portions of letters of credit. Letter Of Credit Executed letter of credit Operating Leases, Future Minimum Payments Receivable Total remaining commitment under the amended and restated sublease Operating Leases, Rent Expense, Net Rent expenses operating leases Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] Future minimum payments: Operating Leases, Future Minimum Payments, Remainder of Fiscal Year Remainder of the year Operating Leases, Future Minimum Payments, Due in Two Years 2020 Operating Leases, Future Minimum Payments, Due in Three Years 2021 Operating Leases, Future Minimum Payments, Due in Four Years 2022 Operating Leases, Future Minimum Payments, Due in Five Years 2023 Operating Leases, Future Minimum Payments, Due Thereafter Thereafter Operating Leases, Future Minimum Payments Due Total future minimum payments Debt Instrument, Face Amount Face amount Debt Instrument, Basis Spread on Variable Rate Spread (as a percent) Debt Instrument, Interest Rate During Period Interest rate (as a percent) Number of periodic payments of principal plus accrued interest (monthly, quarterly, annual). Debt Instrument, Monthly Payments, Number Number of equal monthly payments of principal plus accrued interest