<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.23.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>40</ContextCount>
  <ElementCount>82</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>26</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report instance="findex1461-form.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000000 - Document - Document and Entity Information {Elements}</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.FederatedInvestors.com/role/DocumentDocumentandEntityInformationElements</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="findex1461-form.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>000019 - Disclosure - Risk/Return Detail Data {Elements} - Federated Hermes Mid-Cap Index Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.FederatedInvestors.com/role/DisclosureRiskReturnDetailDataElementsFederatedHermesMid-CapIndexFund</Role>
      <ShortName>Risk/Return Detail Data- Federated Hermes Mid-Cap Index Fund</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="findex1461-form.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>000029 - Disclosure - Risk/Return Detail Data {Elements} - Federated Hermes Max-Cap Index Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.FederatedInvestors.com/role/DisclosureRiskReturnDetailDataElementsFederatedHermesMax-CapIndexFund</Role>
      <ShortName>Risk/Return Detail Data- Federated Hermes Max-Cap Index Fund</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="findex1461-form.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>040000 - Disclosure - Risk/Return Detail Data {Elements}</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/RiskReturnDetailData</Role>
      <ShortName>Risk/Return Detail Data</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>findex-20231227.xsd</File>
    <File>findex-20231227_cal.xml</File>
    <File>findex-20231227_def.xml</File>
    <File>findex-20231227_lab.xml</File>
    <File>findex-20231227_pre.xml</File>
    <File doctype="485BPOS" isN1a="true" isRR="true" isRRorOEF="true" original="findex1461-form.htm">findex1461-form.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>fhilogok11p_2.jpg</File>
    <File>img4867c0c31.gif</File>
    <File>img7cbca0711.gif</File>
    <File>img927da8031.gif</File>
    <File>imgda4dcde91.gif</File>
    <File>mdcfpro2062304a_6.jpg</File>
    <File>mxcfprog0071701_7.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="15">http://xbrl.sec.gov/dei/2023</BaseTaxonomy>
    <BaseTaxonomy items="281">http://xbrl.sec.gov/rr/2023</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
