Document And Entity Information [Abstract] Document Information [Table] Document Information [Line Items] Document Type Document Annual Report Document Period End Date Current Fiscal Year End Date Document Transition Report Entity File Number Entity Registrant Name Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Address, Address Line One Entity Address, City or Town Entity Address, State or Province Entity Address, Postal Zip Code City Area Code Local Phone Number Title of 12(b) Security Trading Symbol Security Exchange 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 ICFR Auditor Attestation Flag Entity Shell Company Entity Public Float Entity Common Stock, Shares Outstanding Auditor Name Auditor Firm ID Auditor Location Entity Central Index Key Document Fiscal Year Focus Document Fiscal Period Focus Amendment Flag Consolidated Balance Sheets Statement [Table] Class of Stock [Axis] Class of Stock [Domain] Series B Convertible Preferred Stock Statement [Line Items] Company's equity incentive plans Assets, Current [Abstract] Current Assets Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Cash and cash equivalents Short-term investments Short-term investments Prepaid Expense and Other Assets, Current Prepaid expenses and other assets Assets, Current Total Current Assets Property, Plant and Equipment, Net Property and equipment, net Property and equipment, net Operating Lease, Right-of-Use Asset Operating lease right-of-use assets Long-term Investments Long-term investments Restricted Cash Restricted cash Restricted cash Other Assets, Noncurrent Long-term assets Assets Total Assets Liabilities, Current [Abstract] Current Liabilities Accounts Payable, Current Accounts payable Accrued Liabilities, Current Accrued expenses Total accrued expenses Operating Lease, Liability, Current Operating lease liabilities - current Current portion included in current liabilities Liabilities, Current Total Current Liabilities Liabilities, Noncurrent [Abstract] Non-Current Liabilities Operating Lease, Liability, Noncurrent Operating lease liabilities - noncurrent Long-term portion included in non-current liabilities Notes Payable, Noncurrent Long-term note payable Other Liabilities, Noncurrent Other liabilities Liabilities, Noncurrent Total Non-Current Liabilities Liabilities Total Liabilities Commitments and Contingencies Commitments and contingencies Consolidated Statements of Stockholders' Equity Stockholders' Equity Preferred Stock, Value, Issued Preferred stock, Value Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive (loss) income Additional Paid in Capital Additional paid-in capital Retained Earnings (Accumulated Deficit) Retained earnings Accumulated deficit Stockholders' Equity Attributable to Parent Ending Balance Beginning Balance Total Stockholders' Equity Liabilities and Equity Total Liabilities and Stockholders' Equity Series A Convertible Preferred Stock Preferred Stock, Par or Stated Value Per Share Preferred stock, par or stated value per share Preferred Stock, Shares Authorized Preferred stock, 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 or stated value per share Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common Stock, Shares, Issued Common stock, shares issued Common Stock, Shares, Outstanding Common Stock, Shares, Outstanding Common stock, shares outstanding Consolidated Statements of Operations Operating Expenses [Abstract] Costs and expenses Research and Development Expense Research and development expenses General and Administrative Expense General and administrative expenses Operating Expenses Total costs and expenses Operating Income (Loss) Loss from operations Nonoperating Income (Expense) [Abstract] Other income Investment Income, Interest Interest income, net Net Income (Loss) Attributable to Parent Net loss Net Loss Net Loss Earnings Per Share, Basic Net Loss Per Share of Common Stock, Basic Earnings Per Share, Diluted Net Loss Per Share of Common Stock, Diluted Weighted Average Number of Shares Outstanding, Basic Weighted Average Shares of Common Stock Outstanding, Basic Weighted Average Number of Shares Outstanding, Diluted Weighted Average Shares of Common Stock Outstanding, Diluted Consolidated Statements of Comprehensive Loss Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Other comprehensive loss / (gain): Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Unrealized loss / (gain) on short-term investments Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive Loss Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of Adoption, Adjustment [Member] Equity Components [Axis] Equity Component [Domain] Preferred Stock Common Stock Additional Paid-In Capital Accumulated Comprehensive Income (Loss) Accumulated Deficit Shares, Outstanding Ending Balance (in Shares) Beginning Balance (in Shares) Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Adoption of ASU 2018-07 Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Stock-based compensation expense Stock Issued During Period, Value, Employee Stock Purchase Plan Common stock issued upon purchase of employee stock purchase plan Stock Issued During Period, Shares, Employee Stock Purchase Plans Common stock issued upon purchase of employee stock purchase plan (in shares) Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Vesting of restricted shares issued for services Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Vesting of restricted shares issued for services (in shares) Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net Tax payments related to shares withheld for vested restricted stock units Stock Issued During Period, Value, Stock Options Exercised Common stock issued upon exercise of stock options Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Exercised Common stock issued upon exercise of stock options (in shares) Stock Issued During Period, Value, New Issues Common stock sold in public offering, net of offering costs Stock Issued During Period, Shares, New Issues Common stock sold in public offering, net of offering costs (in shares) Common stock issued, net of offering costs (in shares) Amount of Common stock issued from preferred stock conversion. Common Stock Issued From Preferred Stock Conversion Common stock issued from preferred stock conversion Number of Common stock issued from preferred stock conversion. Common Stock Issued From Preferred Stock Conversion, Shares Common stock issued from preferred stock conversion (in Shares) Stock Issued During Period, Value, Conversion of Convertible Securities Conversion of convertible preferred stock into common stock Stock Issued During Period, Shares, Conversion of Convertible Securities Conversion of convertible preferred stock into common stock (in Shares) Amount of cancellation shares from settlement of dispute. Stock Cancelled During Period Shares Of Common Stock Cancellation of common shares from settlement of dispute Amount of cancellation shares from settlement of dispute. Cancellation of common shares from settlement of dispute (In Shares) Cancellation of common shares from settlement of dispute (In Shares) Consolidated Statements of Cash Flows Net Cash Provided by (Used in) Operating Activities [Abstract] Cash Flows from 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: Share-based Compensation Stock-based compensation expense Operating Lease, Right-of-Use Asset, Amortization Expense Amortization of right of use asset Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Gain (Loss) Related to Litigation Settlement Gain on settlement of dispute Amortization of Debt Discount (Premium) Accretion (amortization) of discounts and premiums on investments Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property Loss on disposal of assets Increase (Decrease) in Operating Capital [Abstract] Changes in assets and liabilities: Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses, other assets, and long-term assets The increase (decrease) during the period in the carrying value of operating lease liabilities. Increase (Decrease) in Operating Lease Liabilities Operating lease liabilities Increase (Decrease) in Accounts Payable Accounts payable Increase (Decrease) in Accrued Liabilities Accrued expenses and other liabilities Net Cash Provided by (Used in) Operating Activities Net cash used in operating activities Net cash used in operating activities Net Cash Provided by (Used in) Investing Activities [Abstract] Cash Flows from Investing Activities Proceeds from Sale and Maturity of Debt Securities, Available-for-sale Maturities of investments Payments to Acquire Available-for-sale Securities Purchase of investments Payments to Acquire Property, Plant, and Equipment Purchase of property and equipment Net Cash Provided by (Used in) Investing Activities Net cash (used in) provided by investing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Cash Flows from Financing Activities Payments Related to Tax Withholding for Share-based Compensation Tax payments related to shares withheld for vested restricted stock units Proceeds, Issuance of Shares, Share-based Payment Arrangement, Excluding Option Exercised Proceeds from the issuance of common stock upon purchase of employee stock purchase plan Proceeds from Stock Options Exercised Proceeds from the issuance of common stock upon exercise of options Proceeds from Issuance of Common Stock Proceeds from the issuance of common stock, net Proceeds from the issuance of common stock, net Proceeds from Issuance of Long-term Debt Proceeds from the issuance of debt Net Cash Provided by (Used in) Financing Activities Net cash provided in financing activities Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding 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, End of Period Cash, Cash Equivalents, and Restricted Cash, Beginning of Period Total cash, cash equivalents and restricted cash Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental disclosure of non-cash investing and financing activities: Amount of unrealized gain (loss) on short-term investments. Unrealized Gain Loss On Short Term Investments Net unrealized loss on short-term investments The amount of acquisitions of property and equipment included in accounts payable and accrued expense. Acquisitions Of Property And Equipment Included In Accounts Payable And Accrued Expense Acquisitions of property and equipment included in accounts payable and accrued expense Conversion of Stock, Amount Converted Conversion of convertible preferred stock to common stock Amount of vesting of restricted stock units. Vesting Of Restricted Stock Units Vesting of restricted stock units Amount of increase in right-of-use asset obtained in exchange for operating lease liability from new leases. RightOfUseAssetObtainedInExchangeForOperatingLeaseLiabilityFromNewLeases Lease liabilities arising from obtaining right-of-use asset from new leases Amount of increase in right-of-use asset obtained in exchange for operating lease liability from lease modifications. Right-of-Use Asset Obtained in Exchange for Operating Lease Liability From Lease Modifications Lease liabilities arising from obtaining right-of-use asset from lease modifications GENERAL ORGANIZATION AND BUSINESS Business Description and Basis of Presentation [Text Block] GENERAL ORGANIZATION AND BUSINESS SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES Significant Accounting Policies [Text Block] SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES CASH EQUIVALENTS AND INVESTMENTS Cash, Cash Equivalents, and Short-term Investments [Text Block] CASH EQUIVALENTS AND INVESTMENTS PROPERTY AND EQUIPMENT, NET Property, Plant and Equipment Disclosure [Text Block] PROPERTY AND EQUIPMENT, NET ACCRUED EXPENSES Accounts Payable and Accrued Liabilities Disclosure [Text Block] ACCRUED EXPENSES STOCKHOLDERS' EQUITY Stockholders' Equity Note Disclosure [Text Block] STOCKHOLDERS' EQUITY EMPLOYEE BENEFIT PLAN Compensation and Employee Benefit Plans [Text Block] EMPLOYEE BENEFIT PLAN INCOME TAXES Income Tax Disclosure [Text Block] INCOME TAXES LICENSES AND AGREEMENTS The entire disclosure for licenses and agreements. Licenses And Agreements Disclosure [Text Block] LICENSES AND AGREEMENTS LEASES Lessee, Operating Leases [Text Block] LEASES LEGAL PROCEEDINGS Contingencies Disclosure [Text Block] LEGAL PROCEEDINGS LONG-TERM NOTE PAYABLE Long-term Debt [Text Block] LONG-TERM NOTE PAYABLE Cash and Cash Equivalents, Policy [Policy Text Block] Cash, Cash Equivalents, Restricted Cash and Investments Disclosure of accounting policy for restricted cash. Restricted Cash [Policy Text Block] Restricted Cash Property, Plant and Equipment, Policy [Policy Text Block] Property and Equipment, net Earnings Per Share, Policy [Policy Text Block] Loss per Share Fair Value Measurement, Policy [Policy Text Block] Fair Value Measurements Use of Estimates, Policy [Policy Text Block] Use of Estimates Consolidation, Policy [Policy Text Block] Principles of Consolidation Lessee, Leases [Policy Text Block] Leases Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Stock-Based Compensation