<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>206</ContextCount>
  <ElementCount>300</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>81</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-document-and-entity-information</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>001 - Statement - Condensed Consolidated Balance Sheets (Current Period Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-condensed-consolidated-balance-sheets-current-period-unaudited</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Current Period Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>002 - Statement - Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-condensed-consolidated-balance-sheets-current-period-unaudited-parentheticals</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>003 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-condensed-consolidated-statements-of-operations-and-comprehensive-income-loss-unaudited</Role>
      <ShortName>Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>004 - Statement - Condensed Consolidated Statements of Stockholders' Equity (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-condensed-consolidated-statements-of-stockholders-equity-unaudited</Role>
      <ShortName>Condensed Consolidated Statements of Stockholders' Equity (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>005 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-condensed-consolidated-statements-of-cash-flows-unaudited</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>006 - Disclosure - Note 1 - Organization and Nature of Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-1-organization-and-nature-of-business</Role>
      <ShortName>Note 1 - Organization and Nature of Business</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>007 - Disclosure - Note 2 - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-2-summary-of-significant-accounting-policies</Role>
      <ShortName>Note 2 - Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>008 - Disclosure - Note 3 - Fair Value of Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-3-fair-value-of-financial-instruments</Role>
      <ShortName>Note 3 - Fair Value of Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>009 - Disclosure - Note 4 - Balance Sheet Components</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components</Role>
      <ShortName>Note 4 - Balance Sheet Components</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>010 - Disclosure - Note 5 - Revenue</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-5-revenue</Role>
      <ShortName>Note 5 - Revenue</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>011 - Disclosure - Note 6 - Liabilities Related to Sale of Future Royalties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-6-liabilities-related-to-sale-of-future-royalties</Role>
      <ShortName>Note 6 - Liabilities Related to Sale of Future Royalties</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>012 - Disclosure - Note 7 - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-7-leases</Role>
      <ShortName>Note 7 - Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>013 - Disclosure - Note 8 - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-8-commitments-and-contingencies</Role>
      <ShortName>Note 8 - Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>014 - Disclosure - Note 9 - Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-9-stockholders-equity</Role>
      <ShortName>Note 9 - Stockholders' Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>015 - Disclosure - Note 10 - Equity Incentive Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-10-equity-incentive-plans</Role>
      <ShortName>Note 10 - Equity Incentive Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>016 - Disclosure - Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-11-net-income-loss-per-share-attributable-to-common-stockholders</Role>
      <ShortName>Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>017 - Disclosure - Note 12 - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-12-segment-reporting</Role>
      <ShortName>Note 12 - Segment Reporting</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>018 - Disclosure - Note 13 - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-13-subsequent-events-</Role>
      <ShortName>Note 13 - Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995465 - Disclosure - Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-significant-accounting-policies-policies</Role>
      <ShortName>Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-2-summary-of-significant-accounting-policies</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995466 - Disclosure - Note 3 - Fair Value of Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-3-fair-value-of-financial-instruments-tables</Role>
      <ShortName>Note 3 - Fair Value of Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-3-fair-value-of-financial-instruments</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995467 - Disclosure - Note 4 - Balance Sheet Components (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-tables</Role>
      <ShortName>Note 4 - Balance Sheet Components (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995468 - Disclosure - Note 6 - Liabilities Related to Sale of Future Royalties (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-6-liabilities-related-to-sale-of-future-royalties-tables</Role>
      <ShortName>Note 6 - Liabilities Related to Sale of Future Royalties (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-6-liabilities-related-to-sale-of-future-royalties</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995469 - Disclosure - Note 7 - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-7-leases-tables</Role>
      <ShortName>Note 7 - Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-7-leases</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995470 - Disclosure - Note 9 - Stockholders' Equity (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-9-stockholders-equity-tables</Role>
      <ShortName>Note 9 - Stockholders' Equity (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-9-stockholders-equity</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995471 - Disclosure - Note 10 - Equity Incentive Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-10-equity-incentive-plans-tables</Role>
      <ShortName>Note 10 - Equity Incentive Plans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-10-equity-incentive-plans</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995472 - Disclosure - Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-11-net-income-loss-per-share-attributable-to-common-stockholders-tables</Role>
      <ShortName>Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-11-net-income-loss-per-share-attributable-to-common-stockholders</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995473 - Disclosure - Note 12 - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-12-segment-reporting-tables</Role>
      <ShortName>Note 12 - Segment Reporting (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-12-segment-reporting</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995474 - Disclosure - Note 1 - Organization and Nature of Business (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-1-organization-and-nature-of-business-details-textual</Role>
      <ShortName>Note 1 - Organization and Nature of Business (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-1-organization-and-nature-of-business</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995475 - Disclosure - Note 2 - Summary of Significant Accounting Policies (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-2-summary-of-significant-accounting-policies-details-textual</Role>
      <ShortName>Note 2 - Summary of Significant Accounting Policies (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995476 - Disclosure - Note 3 - Fair Value of Financial Instruments (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-3-fair-value-of-financial-instruments-details-textual</Role>
      <ShortName>Note 3 - Fair Value of Financial Instruments (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-3-fair-value-of-financial-instruments-tables</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995477 - Disclosure - Note 3 - Fair Value of Financial Instruments - Financial Assets Measured on a Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-3-fair-value-of-financial-instruments-financial-assets-measured-on-a-recurring-basis-details</Role>
      <ShortName>Note 3 - Fair Value of Financial Instruments - Financial Assets Measured on a Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995478 - Disclosure - Note 4 - Balance Sheet Components (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-details-textual</Role>
      <ShortName>Note 4 - Balance Sheet Components (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-tables</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995479 - Disclosure - Note 4 - Balance Sheet Components - Cash and Cash Equivalents and Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-cash-and-cash-equivalents-and-investments-details</Role>
      <ShortName>Note 4 - Balance Sheet Components - Cash and Cash Equivalents and Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995480 - Disclosure - Note 4 - Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-prepaid-expenses-and-other-current-assets-details</Role>
      <ShortName>Note 4 - Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995481 - Disclosure - Note 4 - Balance Sheet Components - Property and Equipment, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-property-and-equipment-net-details</Role>
      <ShortName>Note 4 - Balance Sheet Components - Property and Equipment, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995482 - Disclosure - Note 4 - Balance Sheet Components - Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-intangible-assets-details</Role>
      <ShortName>Note 4 - Balance Sheet Components - Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995483 - Disclosure - Note 4 - Balance Sheet Components - Estimated Future Amortization Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-estimated-future-amortization-expense-details</Role>
      <ShortName>Note 4 - Balance Sheet Components - Estimated Future Amortization Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995484 - Disclosure - Note 4 - Balance Sheet Components - Deferred Revenue, by Arrangement, Disclosure (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-deferred-revenue-by-arrangement-disclosure-details</Role>
      <ShortName>Note 4 - Balance Sheet Components - Deferred Revenue, by Arrangement, Disclosure (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995485 - Disclosure - Note 4 - Balance Sheet Components - Accrued Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-4-balance-sheet-components-accrued-liabilities-details</Role>
      <ShortName>Note 4 - Balance Sheet Components - Accrued Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995486 - Disclosure - Note 5 - Revenue (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-5-revenue-details-textual</Role>
      <ShortName>Note 5 - Revenue (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-5-revenue</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995487 - Disclosure - Note 6 - Liabilities Related to Sale of Future Royalties (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-6-liabilities-related-to-sale-of-future-royalties-details-textual</Role>
      <ShortName>Note 6 - Liabilities Related to Sale of Future Royalties (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-6-liabilities-related-to-sale-of-future-royalties-tables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995488 - Disclosure - Note 6 - Liabilities Related to Sale of Future Royalties - Deferred Revenue Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-6-liabilities-related-to-sale-of-future-royalties-deferred-revenue-activity-details</Role>
      <ShortName>Note 6 - Liabilities Related to Sale of Future Royalties - Deferred Revenue Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995489 - Disclosure - Note 7 - Leases (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-7-leases-details-textual</Role>
      <ShortName>Note 7 - Leases (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-7-leases-tables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995490 - Disclosure - Note 7 - Leases - Lease Liabilities Payment Obligations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-7-leases-lease-liabilities-payment-obligations-details</Role>
      <ShortName>Note 7 - Leases - Lease Liabilities Payment Obligations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995491 - Disclosure - Note 7 - Leases - Operating Lease Expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-7-leases-operating-lease-expenses-details</Role>
      <ShortName>Note 7 - Leases - Operating Lease Expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>995492 - Disclosure - Note 8 - Commitments and Contingencies (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-8-commitments-and-contingencies-details-textual</Role>
      <ShortName>Note 8 - Commitments and Contingencies (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-8-commitments-and-contingencies</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>995493 - Disclosure - Note 9 - Stockholders' Equity (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-9-stockholders-equity-details-textual</Role>
      <ShortName>Note 9 - Stockholders' Equity (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-9-stockholders-equity-tables</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>995494 - Disclosure - Note 9 - Stockholders' Equity - Shares of Common Stock Reserved for Issuance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-9-stockholders-equity-shares-of-common-stock-reserved-for-issuance-details</Role>
      <ShortName>Note 9 - Stockholders' Equity - Shares of Common Stock Reserved for Issuance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>995495 - Disclosure - Note 9 - Stockholders' Equity - Summary of Warrants Outstanding (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-9-stockholders-equity-summary-of-warrants-outstanding-details</Role>
      <ShortName>Note 9 - Stockholders' Equity - Summary of Warrants Outstanding (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>995496 - Disclosure - Note 10 - Equity Incentive Plans (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-10-equity-incentive-plans-details-textual</Role>
      <ShortName>Note 10 - Equity Incentive Plans (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-10-equity-incentive-plans-tables</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>995497 - Disclosure - Note 10 - Equity Incentive Plans - Summary of Stock Option Transactions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-10-equity-incentive-plans-summary-of-stock-option-transactions-details</Role>
      <ShortName>Note 10 - Equity Incentive Plans - Summary of Stock Option Transactions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>995498 - Disclosure - Note 10 - Equity Incentive Plans - Assumptions of Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-10-equity-incentive-plans-assumptions-of-options-details</Role>
      <ShortName>Note 10 - Equity Incentive Plans - Assumptions of Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>995499 - Disclosure - Note 10 - Equity Incentive Plans - Total Stock-based Compensation Recognized for Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-10-equity-incentive-plans-total-stockbased-compensation-recognized-for-options-details</Role>
      <ShortName>Note 10 - Equity Incentive Plans - Total Stock-based Compensation Recognized for Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>995500 - Disclosure - Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-11-net-income-loss-per-share-attributable-to-common-stockholders-details-textual</Role>
      <ShortName>Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-11-net-income-loss-per-share-attributable-to-common-stockholders-tables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>995501 - Disclosure - Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders - Calculation of Basic and Diluted Net (Loss) Income Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-11-net-income-loss-per-share-attributable-to-common-stockholders-calculation-of-basic-and-diluted-net-loss-income-per-share-details</Role>
      <ShortName>Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders - Calculation of Basic and Diluted Net (Loss) Income Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-11-net-income-loss-per-share-attributable-to-common-stockholders-tables</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>995502 - Disclosure - Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders - Summary of Antidilutive Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-11-net-income-loss-per-share-attributable-to-common-stockholders-summary-of-antidilutive-securities-details</Role>
      <ShortName>Note 11 - Net Income (Loss) Per Share Attributable to Common Stockholders - Summary of Antidilutive Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-11-net-income-loss-per-share-attributable-to-common-stockholders-tables</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>995503 - Disclosure - Note 12 - Segment Reporting (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-12-segment-reporting-details-textual</Role>
      <ShortName>Note 12 - Segment Reporting (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-12-segment-reporting-tables</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>995504 - Disclosure - Note 12 - Segment Reporting - Schedule of Segment Reporting Information, by Segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-12-segment-reporting-schedule-of-segment-reporting-information-by-segment-details</Role>
      <ShortName>Note 12 - Segment Reporting - Schedule of Segment Reporting Information, by Segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="vxrt20260331_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>995505 - Disclosure - Note 13 - Subsequent Events (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.vaxart.com/20260331/role/statement-note-13-subsequent-events-details-textual</Role>
      <ShortName>Note 13 - Subsequent Events (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.vaxart.com/20260331/role/statement-note-13-subsequent-events-</ParentRole>
      <Position>61</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>vxrt-20260331.xsd</File>
    <File>vxrt-20260331_cal.xml</File>
    <File>vxrt-20260331_def.xml</File>
    <File>vxrt-20260331_lab.xml</File>
    <File>vxrt-20260331_pre.xml</File>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="vxrt20260331_10q.htm">vxrt20260331_10q.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="663">http://fasb.org/us-gaap/2026</BaseTaxonomy>
    <BaseTaxonomy items="28">http://xbrl.sec.gov/dei/2026</BaseTaxonomy>
    <BaseTaxonomy items="5">http://xbrl.sec.gov/ecd/2026</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
