<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>488</ContextCount>
  <ElementCount>32</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>44</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>3</UnitCount>
  <MyReports>
    <Report instance="fist2467-form.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>030000 - Disclosure - Form N-CSR Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/NcsrCover</Role>
      <ShortName>Form N-CSR Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="fist2467-form.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>030001 - Disclosure - Shareholder Report</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/ShareholderReport</Role>
      <ShortName>Shareholder Report</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="fist2467-form.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>040010 - Disclosure - Shareholder Report, Line Graph (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/ShareholderReportLineGraphDetails</Role>
      <ShortName>Shareholder Report, Line Graph (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="fist2467-form.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>040015 - Disclosure - Shareholder Report, Average Annual Return (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/ShareholderReportAverageAnnualReturnDetails</Role>
      <ShortName>Shareholder Report, Average Annual Return (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="fist2467-form.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>040020 - Disclosure - Shareholder Report, Holdings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/oef/role/ShareholderReportHoldingsDetails</Role>
      <ShortName>Shareholder Report, Holdings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>federated-20260430.xsd</File>
    <File doctype="N-CSR" isDefinitelyNotFs="true" isNcsr="true" isOEF="true" isRRorOEF="true" isUsgaap="true" original="fist2467-form.htm">fist2467-form.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>ernstyoungsig.jpg</File>
    <File>fhilogok11p.jpg</File>
    <File>i07c696be03cf9a9a0107b56f.jpg</File>
    <File>i379f6e288ec01e987f6a2611.jpg</File>
    <File>i3c1a2722bf0db0b45f5def0d.jpg</File>
    <File>i42308f8a8374a6d9ccc0f874.jpg</File>
    <File>i5457f56d2b1878a210e35212.jpg</File>
    <File>i6db985b6a56f8d8cdd44bbff.jpg</File>
    <File>i7d2b4fea6c471788ea2b421f.jpg</File>
    <File>ic4bf0edba4e97203a7cf9d67.jpg</File>
    <File>ic5b7c9ed46cda8374c190f1a.jpg</File>
    <File>id408c4701ab68ab29228d515.jpg</File>
    <File>ifc6cb77242ffb3e6fd05d3d3.jpg</File>
    <File>img36528baa1.gif</File>
    <File>imge0a8114d1.gif</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="14">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="13">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="693">http://xbrl.sec.gov/oef/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
