<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.22.2.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>232</ContextCount>
  <ElementCount>273</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>83</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001001 - Document - Cover Page</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CoverPage</Role>
      <ShortName>Cover Page</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001002 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002003 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1003004 - Statement - Condensed Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CondensedConsolidatedStatementsofOperations</Role>
      <ShortName>Condensed Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1004005 - Statement - Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CondensedConsolidatedStatementsofConvertiblePreferredStockandStockholdersEquityDeficit</Role>
      <ShortName>Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1005006 - Statement - Condensed Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CondensedConsolidatedStatementsofCashFlows</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>2101101 - Disclosure - Business and Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/BusinessandBasisofPresentation</Role>
      <ShortName>Business and Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>2103102 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/SummaryofSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2106103 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/Acquisitions</Role>
      <ShortName>Acquisitions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2110104 - Disclosure - Fair Value of Financial Assets and Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/FairValueofFinancialAssetsandLiabilities</Role>
      <ShortName>Fair Value of Financial Assets and Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2114105 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/Debt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2116106 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2118107 - Disclosure - Preferred Stock and Common stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/PreferredStockandCommonstock</Role>
      <ShortName>Preferred Stock and Common stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2122108 - Disclosure - Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/StockBasedCompensation</Role>
      <ShortName>Stock-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2128109 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2130110 - Disclosure - Net Loss Per Share Attributable to Compass, Inc.</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/NetLossPerShareAttributabletoCompassInc</Role>
      <ShortName>Net Loss Per Share Attributable to Compass, Inc.</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2134111 - Disclosure - Compass Concierge Receivables and Allowance for Credit Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CompassConciergeReceivablesandAllowanceforCreditLosses</Role>
      <ShortName>Compass Concierge Receivables and Allowance for Credit Losses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2139112 - Disclosure - Restructuring Activities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/RestructuringActivities</Role>
      <ShortName>Restructuring Activities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2204201 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/SummaryofSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://compassinc.com/role/SummaryofSignificantAccountingPolicies</ParentRole>
      <Position>19</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2307301 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/AcquisitionsTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://compassinc.com/role/Acquisitions</ParentRole>
      <Position>20</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2311302 - Disclosure - Fair Value of Financial Assets and Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/FairValueofFinancialAssetsandLiabilitiesTables</Role>
      <ShortName>Fair Value of Financial Assets and Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://compassinc.com/role/FairValueofFinancialAssetsandLiabilities</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2319303 - Disclosure - Preferred Stock and Common stock (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/PreferredStockandCommonstockTables</Role>
      <ShortName>Preferred Stock and Common stock (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://compassinc.com/role/PreferredStockandCommonstock</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2323304 - Disclosure - Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/StockBasedCompensationTables</Role>
      <ShortName>Stock-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://compassinc.com/role/StockBasedCompensation</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2331305 - Disclosure - Net Loss Per Share Attributable to Compass, Inc. (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/NetLossPerShareAttributabletoCompassIncTables</Role>
      <ShortName>Net Loss Per Share Attributable to Compass, Inc. (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://compassinc.com/role/NetLossPerShareAttributabletoCompassInc</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2335306 - Disclosure - Compass Concierge Receivables and Allowance for Credit Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CompassConciergeReceivablesandAllowanceforCreditLossesTables</Role>
      <ShortName>Compass Concierge Receivables and Allowance for Credit Losses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://compassinc.com/role/CompassConciergeReceivablesandAllowanceforCreditLosses</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2340307 - Disclosure - Restructuring Activities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/RestructuringActivitiesTables</Role>
      <ShortName>Restructuring Activities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://compassinc.com/role/RestructuringActivities</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2402401 - Disclosure - Business and Basis of Presentation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/BusinessandBasisofPresentationAdditionalInformationDetail</Role>
      <ShortName>Business and Basis of Presentation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2405402 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/SummaryofSignificantAccountingPoliciesAdditionalInformationDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2408403 - Disclosure - Acquisitions - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/AcquisitionsAdditionalInformationDetail</Role>
      <ShortName>Acquisitions - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2409404 - Disclosure - Acquisitions - Summary of Changes in Contingent Consideration Measured at Fair Value on a Recurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/AcquisitionsSummaryofChangesinContingentConsiderationMeasuredatFairValueonaRecurringBasisDetail</Role>
      <ShortName>Acquisitions - Summary of Changes in Contingent Consideration Measured at Fair Value on a Recurring Basis (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2412405 - Disclosure - Fair Value of Financial Assets and Liabilities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/FairValueofFinancialAssetsandLiabilitiesAdditionalInformationDetail</Role>
      <ShortName>Fair Value of Financial Assets and Liabilities - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2413406 - Disclosure - Fair Value of Financial Assets and Liabilities - Balances of Contingent Consideration (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/FairValueofFinancialAssetsandLiabilitiesBalancesofContingentConsiderationDetail</Role>
      <ShortName>Fair Value of Financial Assets and Liabilities - Balances of Contingent Consideration (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2415407 - Disclosure - Debt - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/DebtAdditionalInformationDetail</Role>
      <ShortName>Debt - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2417408 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CommitmentsandContingenciesAdditionalInformationDetail</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2420409 - Disclosure - Preferred Stock and Common stock - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/PreferredStockandCommonstockAdditionalInformationDetail</Role>
      <ShortName>Preferred Stock and Common stock - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2421410 - Disclosure - Preferred Stock and Common stock - Schedule of Stock by Class (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/PreferredStockandCommonstockScheduleofStockbyClassDetail</Role>
      <ShortName>Preferred Stock and Common stock - Schedule of Stock by Class (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2424411 - Disclosure - Stock-Based Compensation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/StockBasedCompensationAdditionalInformationDetail</Role>
      <ShortName>Stock-Based Compensation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2425412 - Disclosure - Stock-Based Compensation - Summary of Stock Option Activity (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/StockBasedCompensationSummaryofStockOptionActivityDetail</Role>
      <ShortName>Stock-Based Compensation - Summary of Stock Option Activity (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2426413 - Disclosure - Stock-Based Compensation - Summary of Restricted Stock Units Activity (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/StockBasedCompensationSummaryofRestrictedStockUnitsActivityDetail</Role>
      <ShortName>Stock-Based Compensation - Summary of Restricted Stock Units Activity (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2427414 - Disclosure - Stock-Based Compensation - Share-based Payment Arrangement, Expensed and Capitalized, Amount (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/StockBasedCompensationSharebasedPaymentArrangementExpensedandCapitalizedAmountDetail</Role>
      <ShortName>Stock-Based Compensation - Share-based Payment Arrangement, Expensed and Capitalized, Amount (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2429415 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/IncomeTaxesAdditionalInformationDetail</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2432416 - Disclosure - Net Loss Per Share Attributable to Compass, Inc. - Schedule of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/NetLossPerShareAttributabletoCompassIncScheduleofComputationofBasicandDilutedNetLossPerShareAttributabletoCommonStockholdersDetail</Role>
      <ShortName>Net Loss Per Share Attributable to Compass, Inc. - Schedule of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2433417 - Disclosure - Net Loss Per Share Attributable to Compass, Inc. - Schedule of Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/NetLossPerShareAttributabletoCompassIncScheduleofComputationofDilutedNetLossPerShareAttributabletoCommonStockholdersDetail</Role>
      <ShortName>Net Loss Per Share Attributable to Compass, Inc. - Schedule of Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2436418 - Disclosure - Compass Concierge Receivables and Allowance for Credit Losses - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CompassConciergeReceivablesandAllowanceforCreditLossesAdditionalInformationDetail</Role>
      <ShortName>Compass Concierge Receivables and Allowance for Credit Losses - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2437419 - Disclosure - Compass Concierge Receivables and Allowance for Credit Losses - Summary of ACL for Concierge Receivables (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CompassConciergeReceivablesandAllowanceforCreditLossesSummaryofACLforConciergeReceivablesDetail</Role>
      <ShortName>Compass Concierge Receivables and Allowance for Credit Losses - Summary of ACL for Concierge Receivables (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2438420 - Disclosure - Compass Concierge Receivables and Allowance for Credit Losses - Summary of Aging Analysis of Concierge Receivables (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/CompassConciergeReceivablesandAllowanceforCreditLossesSummaryofAgingAnalysisofConciergeReceivablesDetail</Role>
      <ShortName>Compass Concierge Receivables and Allowance for Credit Losses - Summary of Aging Analysis of Concierge Receivables (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2441421 - Disclosure - Restructuring Activities - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/RestructuringActivitiesNarrativeDetails</Role>
      <ShortName>Restructuring Activities - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="comp-20220630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2442422 - Disclosure - Restructuring Activities - Total Costs Incurred and Expected to be Incurred (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://compassinc.com/role/RestructuringActivitiesTotalCostsIncurredandExpectedtobeIncurredDetails</Role>
      <ShortName>Restructuring Activities - Total Costs Incurred and Expected to be Incurred (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Warning">[ix-0514-Hidden-Fact-Eligible-For-Transform] WARN: 2 fact(s) appearing in ix:hidden were eligible for transformation: comp:CommonStockNumberOfVotes, us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1 -  comp-20220630.htm 4</Log>
  </Logs>
  <InputFiles>
    <File doctype="10-Q" original="comp-20220630.htm">comp-20220630.htm</File>
    <File>comp-20220630.xsd</File>
    <File>comp-20220630_cal.xml</File>
    <File>comp-20220630_def.xml</File>
    <File>comp-20220630_lab.xml</File>
    <File>comp-20220630_pre.xml</File>
    <File>comp-20220630x10qex101.htm</File>
    <File>comp-20220630x10qex102.htm</File>
    <File>comp-20220630x10qex103.htm</File>
    <File>comp-20220630x10qex311.htm</File>
    <File>comp-20220630x10qex312.htm</File>
    <File>comp-20220630x10qex321.htm</File>
    <File>comp-20220630x10qex322.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="704">http://fasb.org/us-gaap/2022</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2022</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
