<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>92</ContextCount>
  <ElementCount>29</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>11</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report instance="fix014562-def14a.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://comfortsystemsusa.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="fix014562-def14a.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="fix014562-def14a.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="fix014562-def14a.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>fix-20260518.xsd</File>
    <File>fix-20260518_def.xml</File>
    <File>fix-20260518_lab.xml</File>
    <File>fix-20260518_pre.xml</File>
    <File doctype="DEF 14A" isProxy="true" isUsgaap="true" original="fix014562-def14a.htm">fix014562-def14a.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>fix_logo.jpg</File>
    <File>footer.jpg</File>
    <File>pro014562-def14ax10x1.jpg</File>
    <File>pro014562-def14ax10x2.jpg</File>
    <File>pro014562-def14ax10x3.jpg</File>
    <File>pro014562-def14ax10x4.jpg</File>
    <File>pro014562-def14ax10x5.jpg</File>
    <File>pro014562-def14ax10x6.jpg</File>
    <File>pro014562-def14ax11x1.jpg</File>
    <File>pro014562-def14ax11x2.jpg</File>
    <File>pro014562-def14ax11x3.jpg</File>
    <File>pro014562-def14ax12x1.jpg</File>
    <File>pro014562-def14ax12x2.jpg</File>
    <File>pro014562-def14ax12x3.jpg</File>
    <File>pro014562-def14ax13x1.jpg</File>
    <File>pro014562-def14ax16x1.jpg</File>
    <File>pro014562-def14ax16x2.jpg</File>
    <File>pro014562-def14ax16x3.jpg</File>
    <File>pro014562-def14ax16x4.jpg</File>
    <File>pro014562-def14ax16x5.jpg</File>
    <File>pro014562-def14ax16x6.jpg</File>
    <File>pro014562-def14ax16x7.jpg</File>
    <File>pro014562-def14ax16x8.jpg</File>
    <File>pro014562-def14ax17x1.jpg</File>
    <File>pro014562-def14ax17x2.jpg</File>
    <File>pro014562-def14ax18x1.jpg</File>
    <File>pro014562-def14ax18x2.jpg</File>
    <File>pro014562-def14ax19x1.jpg</File>
    <File>pro014562-def14ax19x2.jpg</File>
    <File>pro014562-def14ax1x1.jpg</File>
    <File>pro014562-def14ax20x1.jpg</File>
    <File>pro014562-def14ax20x2.jpg</File>
    <File>pro014562-def14ax21x1.jpg</File>
    <File>pro014562-def14ax21x2.jpg</File>
    <File>pro014562-def14ax21x3.jpg</File>
    <File>pro014562-def14ax22x1.jpg</File>
    <File>pro014562-def14ax22x10.jpg</File>
    <File>pro014562-def14ax22x11.jpg</File>
    <File>pro014562-def14ax22x12.jpg</File>
    <File>pro014562-def14ax22x13.jpg</File>
    <File>pro014562-def14ax22x14.jpg</File>
    <File>pro014562-def14ax22x15.jpg</File>
    <File>pro014562-def14ax22x16.jpg</File>
    <File>pro014562-def14ax22x17.jpg</File>
    <File>pro014562-def14ax22x18.jpg</File>
    <File>pro014562-def14ax22x19.jpg</File>
    <File>pro014562-def14ax22x2.jpg</File>
    <File>pro014562-def14ax22x20.jpg</File>
    <File>pro014562-def14ax22x21.jpg</File>
    <File>pro014562-def14ax22x22.jpg</File>
    <File>pro014562-def14ax22x3.jpg</File>
    <File>pro014562-def14ax22x4.jpg</File>
    <File>pro014562-def14ax22x5.jpg</File>
    <File>pro014562-def14ax22x6.jpg</File>
    <File>pro014562-def14ax22x7.jpg</File>
    <File>pro014562-def14ax22x8.jpg</File>
    <File>pro014562-def14ax22x9.jpg</File>
    <File>pro014562-def14ax23x1.jpg</File>
    <File>pro014562-def14ax23x2.jpg</File>
    <File>pro014562-def14ax23x3.jpg</File>
    <File>pro014562-def14ax23x4.jpg</File>
    <File>pro014562-def14ax23x5.jpg</File>
    <File>pro014562-def14ax23x6.jpg</File>
    <File>pro014562-def14ax24x1.jpg</File>
    <File>pro014562-def14ax24x2.jpg</File>
    <File>pro014562-def14ax24x3.jpg</File>
    <File>pro014562-def14ax24x4.jpg</File>
    <File>pro014562-def14ax24x5.jpg</File>
    <File>pro014562-def14ax25x1.jpg</File>
    <File>pro014562-def14ax25x2.jpg</File>
    <File>pro014562-def14ax25x3.jpg</File>
    <File>pro014562-def14ax25x4.jpg</File>
    <File>pro014562-def14ax2x1.jpg</File>
    <File>pro014562-def14ax31x1.jpg</File>
    <File>pro014562-def14ax35x1.jpg</File>
    <File>pro014562-def14ax36x1.jpg</File>
    <File>pro014562-def14ax37x1.jpg</File>
    <File>pro014562-def14ax3x1.jpg</File>
    <File>pro014562-def14ax3x2.jpg</File>
    <File>pro014562-def14ax3x3.jpg</File>
    <File>pro014562-def14ax40x1.jpg</File>
    <File>pro014562-def14ax40x2.jpg</File>
    <File>pro014562-def14ax41x1.jpg</File>
    <File>pro014562-def14ax41x2.jpg</File>
    <File>pro014562-def14ax44x1.jpg</File>
    <File>pro014562-def14ax46x1.jpg</File>
    <File>pro014562-def14ax4x1.jpg</File>
    <File>pro014562-def14ax4x10.jpg</File>
    <File>pro014562-def14ax4x2.jpg</File>
    <File>pro014562-def14ax4x3.jpg</File>
    <File>pro014562-def14ax4x4.jpg</File>
    <File>pro014562-def14ax4x5.jpg</File>
    <File>pro014562-def14ax4x6.jpg</File>
    <File>pro014562-def14ax4x7.jpg</File>
    <File>pro014562-def14ax4x8.jpg</File>
    <File>pro014562-def14ax4x9.jpg</File>
    <File>pro014562-def14ax50x1.jpg</File>
    <File>pro014562-def14ax50x2.jpg</File>
    <File>pro014562-def14ax50x3.jpg</File>
    <File>pro014562-def14ax50x4.jpg</File>
    <File>pro014562-def14ax50x5.jpg</File>
    <File>pro014562-def14ax64x1.jpg</File>
    <File>pro014562-def14ax67x1.jpg</File>
    <File>pro014562-def14ax68x1.jpg</File>
    <File>pro014562-def14ax68x2.jpg</File>
    <File>pro014562-def14ax69x1.jpg</File>
    <File>pro014562-def14ax6x1.jpg</File>
    <File>pro014562-def14ax6x2.jpg</File>
    <File>pro014562-def14ax6x3.jpg</File>
    <File>pro014562-def14ax6x4.jpg</File>
    <File>pro014562-def14ax6x5.jpg</File>
    <File>pro014562-def14ax6x6.jpg</File>
    <File>pro014562-def14ax6x7.jpg</File>
    <File>pro014562-def14ax6x8.jpg</File>
    <File>pro014562-def14ax76x1.jpg</File>
    <File>pro014562-def14ax7x1.jpg</File>
    <File>pro014562-def14ax7x10.jpg</File>
    <File>pro014562-def14ax7x11.jpg</File>
    <File>pro014562-def14ax7x12.jpg</File>
    <File>pro014562-def14ax7x13.jpg</File>
    <File>pro014562-def14ax7x14.jpg</File>
    <File>pro014562-def14ax7x15.jpg</File>
    <File>pro014562-def14ax7x2.jpg</File>
    <File>pro014562-def14ax7x3.jpg</File>
    <File>pro014562-def14ax7x4.jpg</File>
    <File>pro014562-def14ax7x5.jpg</File>
    <File>pro014562-def14ax7x6.jpg</File>
    <File>pro014562-def14ax7x7.jpg</File>
    <File>pro014562-def14ax7x8.jpg</File>
    <File>pro014562-def14ax7x9.jpg</File>
    <File>pro014562-def14ax8x1.jpg</File>
    <File>pro014562-def14ax8x10.jpg</File>
    <File>pro014562-def14ax8x11.jpg</File>
    <File>pro014562-def14ax8x12.jpg</File>
    <File>pro014562-def14ax8x13.jpg</File>
    <File>pro014562-def14ax8x14.jpg</File>
    <File>pro014562-def14ax8x15.jpg</File>
    <File>pro014562-def14ax8x16.jpg</File>
    <File>pro014562-def14ax8x17.jpg</File>
    <File>pro014562-def14ax8x19.jpg</File>
    <File>pro014562-def14ax8x2.jpg</File>
    <File>pro014562-def14ax8x20.jpg</File>
    <File>pro014562-def14ax8x21.jpg</File>
    <File>pro014562-def14ax8x22.jpg</File>
    <File>pro014562-def14ax8x23.jpg</File>
    <File>pro014562-def14ax8x24.jpg</File>
    <File>pro014562-def14ax8x3.jpg</File>
    <File>pro014562-def14ax8x4.jpg</File>
    <File>pro014562-def14ax8x5.jpg</File>
    <File>pro014562-def14ax8x6.jpg</File>
    <File>pro014562-def14ax8x7.jpg</File>
    <File>pro014562-def14ax8x8.jpg</File>
    <File>pro014562-def14ax8x9.jpg</File>
    <File>pro014562-def14ax9x1.jpg</File>
    <File>pro014562-def14ax9x2.jpg</File>
    <File>proxy1.jpg</File>
    <File>proxy2.jpg</File>
    <File>proxy3.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="167">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
