<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>81</ContextCount>
  <ElementCount>152</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>24</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="xbit20260630_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://xbiotech.com/20260630/role/statement-document-and-entity-information</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="xbit20260630_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://xbiotech.com/20260630/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="xbit20260630_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://xbiotech.com/20260630/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="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>003 - Statement - Condensed Consolidated Statements of Operations (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-condensed-consolidated-statements-of-operations-unaudited</Role>
      <ShortName>Condensed Consolidated Statements of Operations (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>004 - Statement - Condensed Consolidated Statements of Shareholders' Equity (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-condensed-consolidated-statements-of-shareholders-equity-unaudited</Role>
      <ShortName>Condensed Consolidated Statements of Shareholders' Equity (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="xbit20260630_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://xbiotech.com/20260630/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="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>006 - Disclosure - Note 1 - Organization</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-1-organization</Role>
      <ShortName>Note 1 - Organization</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>007 - Disclosure - Note 2 - Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-2-significant-accounting-policies</Role>
      <ShortName>Note 2 - Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>008 - Disclosure - Note 3 - Property and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-3-property-and-equipment</Role>
      <ShortName>Note 3 - Property and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>009 - Disclosure - Note 4 - Convertible Loan, Related Party</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-4-convertible-loan-related-party</Role>
      <ShortName>Note 4 - Convertible Loan, Related Party</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>010 - Disclosure - Note 5 - Common Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-5-common-stock</Role>
      <ShortName>Note 5 - Common Stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>011 - Disclosure - Note 6 - Common Stock Options</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-6-common-stock-options</Role>
      <ShortName>Note 6 - Common Stock Options</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>012 - Disclosure - Note 7 - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-7-income-taxes</Role>
      <ShortName>Note 7 - Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.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>14</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-significant-accounting-policies-policies</Role>
      <ShortName>Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-2-significant-accounting-policies</ParentRole>
      <Position>15</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995446 - Disclosure - Note 2 - Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-2-significant-accounting-policies-tables</Role>
      <ShortName>Note 2 - Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-2-significant-accounting-policies</ParentRole>
      <Position>16</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995447 - Disclosure - Note 3 - Property and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-3-property-and-equipment-tables</Role>
      <ShortName>Note 3 - Property and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-3-property-and-equipment</ParentRole>
      <Position>17</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995448 - Disclosure - Note 6 - Common Stock Options (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-6-common-stock-options-tables</Role>
      <ShortName>Note 6 - Common Stock Options (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-6-common-stock-options</ParentRole>
      <Position>18</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995449 - Disclosure - Note 1 - Organization (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-1-organization-details-textual</Role>
      <ShortName>Note 1 - Organization (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-1-organization</ParentRole>
      <Position>19</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995450 - Disclosure - Note 2 - Significant Accounting Policies (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-2-significant-accounting-policies-details-textual</Role>
      <ShortName>Note 2 - Significant Accounting Policies (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-2-significant-accounting-policies-tables</ParentRole>
      <Position>20</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995451 - Disclosure - Note 2 - Significant Accounting Policies - Share-based Compensation Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-2-significant-accounting-policies-sharebased-compensation-expense-details</Role>
      <ShortName>Note 2 - Significant Accounting Policies - Share-based Compensation Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995452 - Disclosure - Note 2 - Significant Accounting Policies - Stock Option Valuation Assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-2-significant-accounting-policies-stock-option-valuation-assumptions-details</Role>
      <ShortName>Note 2 - Significant Accounting Policies - Stock Option Valuation Assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995453 - Disclosure - Note 3 - Property and Equipment - Property and Equipment, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-3-property-and-equipment-property-and-equipment-net-details</Role>
      <ShortName>Note 3 - Property and Equipment - Property and Equipment, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995454 - Disclosure - Note 4 - Convertible Loan, Related Party (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-4-convertible-loan-related-party-details-textual</Role>
      <ShortName>Note 4 - Convertible Loan, Related Party (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-4-convertible-loan-related-party</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995455 - Disclosure - Note 5 - Common Stock (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-5-common-stock-details-textual</Role>
      <ShortName>Note 5 - Common Stock (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-5-common-stock</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995456 - Disclosure - Note 6 - Common Stock Options (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-6-common-stock-options-details-textual</Role>
      <ShortName>Note 6 - Common Stock Options (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-6-common-stock-options-tables</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995457 - Disclosure - Note 6 - Common Stock Options - Changes in Common Stock Options Issued (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-6-common-stock-options-changes-in-common-stock-options-issued-details</Role>
      <ShortName>Note 6 - Common Stock Options - Changes in Common Stock Options Issued (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="xbit20260630_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995458 - Disclosure - Note 7 - Income Taxes (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbiotech.com/20260630/role/statement-note-7-income-taxes-details-textual</Role>
      <ShortName>Note 7 - Income Taxes (Details Textual)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://xbiotech.com/20260630/role/statement-note-7-income-taxes</ParentRole>
      <Position>28</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>xbit-20260630.xsd</File>
    <File>xbit-20260630_cal.xml</File>
    <File>xbit-20260630_def.xml</File>
    <File>xbit-20260630_lab.xml</File>
    <File>xbit-20260630_pre.xml</File>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="xbit20260630_10q.htm">xbit20260630_10q.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="341">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>
