<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>102</ContextCount>
  <ElementCount>31</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>14</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report instance="d949689ddef14a.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>995100 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/dei/role/document/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="d949689ddef14a.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="d949689ddef14a.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>995443 - Disclosure - Award Timing Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/AwardTimingDisclosure</Role>
      <ShortName>Award Timing Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="d949689ddef14a.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>995447 - Disclosure - Insider Trading Policies and Procedures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingPoliciesProc</Role>
      <ShortName>Insider Trading Policies and Procedures</ShortName>
      <MenuCategory>Notes</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 doctype="DEF 14A" isProxy="true" isUsgaap="true" original="d949689ddef14a.htm">d949689ddef14a.htm</File>
    <File>trmk-20251231.xsd</File>
  </InputFiles>
  <SupplementalFiles>
    <File>g949689dsp0020.jpg</File>
    <File>g949689dsp03a.jpg</File>
    <File>g949689dsp03b.jpg</File>
    <File>g949689dsp05a.jpg</File>
    <File>g949689dsp05b.jpg</File>
    <File>g949689dsp05c.jpg</File>
    <File>g949689dsp05d.jpg</File>
    <File>g949689dsp20.jpg</File>
    <File>g949689dsp21a.jpg</File>
    <File>g949689dsp21b.jpg</File>
    <File>g949689dsp22a.jpg</File>
    <File>g949689dsp22b.jpg</File>
    <File>g949689dsp23a.jpg</File>
    <File>g949689dsp23b.jpg</File>
    <File>g949689dsp24a.jpg</File>
    <File>g949689dsp24b.jpg</File>
    <File>g949689dsp25a.jpg</File>
    <File>g949689dsp25b.jpg</File>
    <File>g949689dsp28.jpg</File>
    <File>g949689dsp45a.jpg</File>
    <File>g949689dsp45b.jpg</File>
    <File>g949689dsp46a.jpg</File>
    <File>g949689dsp46b.jpg</File>
    <File>g949689dsp58.jpg</File>
    <File>g949689dsp58a.jpg</File>
    <File>g949689dsp59.jpg</File>
    <File>g949689g02d11.jpg</File>
    <File>g949689g03d11.jpg</File>
    <File>g949689g04d11.jpg</File>
    <File>g949689page27.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="5">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="169">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
