<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.23.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>257</ContextCount>
  <ElementCount>381</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>88</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>9</UnitCount>
  <MyReports>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00105 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00200 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/StatementConsolidatedStatementsOfOperations</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00300 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/StatementConsolidatedStatementsOfChangesInStockholdersEquity</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00400 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>10101 - Disclosure - Organization and Description of Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureOrganizationAndDescriptionOfBusiness</Role>
      <ShortName>Organization and Description of Business</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10201 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10301 - Disclosure - Property, Equipment and Software, net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosurePropertyEquipmentAndSoftwareNet</Role>
      <ShortName>Property, Equipment and Software, net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10401 - Disclosure - Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureIntangibleAssets</Role>
      <ShortName>Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10501 - Disclosure - Accrued Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureAccruedLiabilities</Role>
      <ShortName>Accrued Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10601 - Disclosure - Long-Term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureLongTermDebt</Role>
      <ShortName>Long-Term Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10701 - Disclosure - Mandatorily Redeemable Preferred Units</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureMandatorilyRedeemablePreferredUnits</Role>
      <ShortName>Mandatorily Redeemable Preferred Units</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10801 - Disclosure - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureRelatedPartyTransactions</Role>
      <ShortName>Related Party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10901 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>11001 - Disclosure - Stockholders' Equity and Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensation</Role>
      <ShortName>Stockholders' Equity and Stock-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>11101 - Disclosure - Income (Loss) Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureIncomeLossPerShare</Role>
      <ShortName>Income (Loss) Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11201 - Disclosure - Employee Benefit Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureEmployeeBenefitPlans</Role>
      <ShortName>Employee Benefit Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11301 - Disclosure - Tax Receivable Agreement and Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureTaxReceivableAgreementAndIncomeTaxes</Role>
      <ShortName>Tax Receivable Agreement and Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11401 - Disclosure - Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureSegmentInformation</Role>
      <ShortName>Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>11501 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>20202 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>30103 - Disclosure - Organization and Description of Business (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureOrganizationAndDescriptionOfBusinessTables</Role>
      <ShortName>Organization and Description of Business (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureOrganizationAndDescriptionOfBusiness</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>30303 - Disclosure - Property, Equipment and Software, net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosurePropertyEquipmentAndSoftwareNetTables</Role>
      <ShortName>Property, Equipment and Software, net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosurePropertyEquipmentAndSoftwareNet</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>30403 - Disclosure - Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureIntangibleAssetsTables</Role>
      <ShortName>Intangible Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureIntangibleAssets</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>30503 - Disclosure - Accrued Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureAccruedLiabilitiesTables</Role>
      <ShortName>Accrued Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureAccruedLiabilities</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>30603 - Disclosure - Long-Term Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureLongTermDebtTables</Role>
      <ShortName>Long-Term Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureLongTermDebt</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>30803 - Disclosure - Related Party Transactions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureRelatedPartyTransactionsTables</Role>
      <ShortName>Related Party Transactions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureRelatedPartyTransactions</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>30903 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureCommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>31003 - Disclosure - Stockholders' Equity and Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensationTables</Role>
      <ShortName>Stockholders' Equity and Stock-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensation</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>31103 - Disclosure - Income (Loss) Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureIncomeLossPerShareTables</Role>
      <ShortName>Income (Loss) Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureIncomeLossPerShare</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>31303 - Disclosure - Tax Receivable Agreement and Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureTaxReceivableAgreementAndIncomeTaxesTables</Role>
      <ShortName>Tax Receivable Agreement and Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureTaxReceivableAgreementAndIncomeTaxes</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>31403 - Disclosure - Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureSegmentInformationTables</Role>
      <ShortName>Segment Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureSegmentInformation</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>40101 - Disclosure - Organization and Description of Business (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureOrganizationAndDescriptionOfBusinessDetails</Role>
      <ShortName>Organization and Description of Business (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureOrganizationAndDescriptionOfBusinessTables</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>40201 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesCashAndCashEquivalentsDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>40202 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Accounts Receivable (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesAccountsReceivableDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Accounts Receivable (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>40203 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Concentration of customers (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesConcentrationOfCustomersDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Concentration of customers (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>40204 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Property and Equipment, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPropertyAndEquipmentNetDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Property and Equipment, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>40205 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesGoodwillDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Goodwill (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>40206 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Deferred Financing Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDeferredFinancingCostsDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Deferred Financing Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>40207 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Revenue Recognition (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesRevenueRecognitionDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Revenue Recognition (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>40208 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Advertising Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesAdvertisingCostsDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Advertising Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>40209 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesIncomeTaxesDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>40210 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Segment Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesSegmentInformationDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Segment Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>40211 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies - Liquidity and Capital Resources (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureBasisOfPresentationAndSummaryOfSignificantAccountingPoliciesLiquidityAndCapitalResourcesDetails</Role>
      <ShortName>Basis of Presentation and Summary of Significant Accounting Policies - Liquidity and Capital Resources (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>40301 - Disclosure - Property, Equipment and Software, net - Components (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosurePropertyEquipmentAndSoftwareNetComponentsDetails</Role>
      <ShortName>Property, Equipment and Software, net - Components (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>40302 - Disclosure - Property, Equipment and Software, net - Depreciation and Amortization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosurePropertyEquipmentAndSoftwareNetDepreciationAndAmortizationDetails</Role>
      <ShortName>Property, Equipment and Software, net - Depreciation and Amortization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>40401 - Disclosure - Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureIntangibleAssetsDetails</Role>
      <ShortName>Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureIntangibleAssetsTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>40402 - Disclosure - Intangible Assets - Schedule of Intangible Assets and Related Accumulated Amortization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureIntangibleAssetsScheduleOfIntangibleAssetsAndRelatedAccumulatedAmortizationDetails</Role>
      <ShortName>Intangible Assets - Schedule of Intangible Assets and Related Accumulated Amortization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>40403 - Disclosure - Intangible Assets - Future Amortization Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureIntangibleAssetsFutureAmortizationExpenseDetails</Role>
      <ShortName>Intangible Assets - Future Amortization Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>40501 - Disclosure - Accrued Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureAccruedLiabilitiesDetails</Role>
      <ShortName>Accrued Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureAccruedLiabilitiesTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>40502 - Disclosure - Accrued Liabilities - Additional information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureAccruedLiabilitiesAdditionalInformationDetails</Role>
      <ShortName>Accrued Liabilities - Additional information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>40601 - Disclosure - Long-Term Debt - Lafayette Square (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureLongTermDebtLafayetteSquareDetails</Role>
      <ShortName>Long-Term Debt - Lafayette Square (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>40602 - Disclosure - Long-Term Debt - Interest Expense and 2021 Credit Facility (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureLongTermDebtInterestExpenseAnd2021CreditFacilityDetails</Role>
      <ShortName>Long-Term Debt - Interest Expense and 2021 Credit Facility (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>40603 - Disclosure - Long-Term Debt - 2020 Revolving Line of Credit (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureLongTermDebt2020RevolvingLineOfCreditDetails</Role>
      <ShortName>Long-Term Debt - 2020 Revolving Line of Credit (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>40604 - Disclosure - Long-Term Debt - Interest Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureLongTermDebtInterestExpenseDetails</Role>
      <ShortName>Long-Term Debt - Interest Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>40605 - Disclosure - Long-Term Debt - Silicon Valley Bank Financing (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureLongTermDebtSiliconValleyBankFinancingDetails</Role>
      <ShortName>Long-Term Debt - Silicon Valley Bank Financing (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>40606 - Disclosure - Long-Term Debt - U.S. Small Business Administration Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureLongTermDebtUsSmallBusinessAdministrationLoansDetails</Role>
      <ShortName>Long-Term Debt - U.S. Small Business Administration Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>40607 - Disclosure - Long-Term Debt - Future Minimum Payments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureLongTermDebtFutureMinimumPaymentsDetails</Role>
      <ShortName>Long-Term Debt - Future Minimum Payments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>40701 - Disclosure - Mandatorily Redeemable Preferred Units (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureMandatorilyRedeemablePreferredUnitsDetails</Role>
      <ShortName>Mandatorily Redeemable Preferred Units (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureMandatorilyRedeemablePreferredUnits</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>40801 - Disclosure - Related Party Transactions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureRelatedPartyTransactionsDetails</Role>
      <ShortName>Related Party Transactions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureRelatedPartyTransactionsTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>40802 - Disclosure - Related Party Transactions - Schedule of aggregate changes in balance of gross unrecognized tax benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureRelatedPartyTransactionsScheduleOfAggregateChangesInBalanceOfGrossUnrecognizedTaxBenefitsDetails</Role>
      <ShortName>Related Party Transactions - Schedule of aggregate changes in balance of gross unrecognized tax benefits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>40901 - Disclosure - Commitments and Contingencies - Litigation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureCommitmentsAndContingenciesLitigationDetails</Role>
      <ShortName>Commitments and Contingencies - Litigation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>40902 - Disclosure - Commitments and Contingencies - Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureCommitmentsAndContingenciesLeasesDetails</Role>
      <ShortName>Commitments and Contingencies - Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>40903 - Disclosure - Commitments and Contingencies - Maturity of Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureCommitmentsAndContingenciesMaturityOfLeasesDetails</Role>
      <ShortName>Commitments and Contingencies - Maturity of Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>41001 - Disclosure - Stockholders' Equity and Stock-Based Compensation - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensationNarrativeDetails</Role>
      <ShortName>Stockholders' Equity and Stock-Based Compensation - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensationTables</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>41002 - Disclosure - Stockholders' Equity and Stock-Based Compensation - Warrants assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensationWarrantsAssumptionsDetails</Role>
      <ShortName>Stockholders' Equity and Stock-Based Compensation - Warrants assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>41003 - Disclosure - Stockholders' Equity and Stock-Based Compensation - Warrants Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensationWarrantsActivityDetails</Role>
      <ShortName>Stockholders' Equity and Stock-Based Compensation - Warrants Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>41004 - Disclosure - Stockholders' Equity and Stock-Based Compensation - Options and RSU Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensationOptionsAndRsuNarrativeDetails</Role>
      <ShortName>Stockholders' Equity and Stock-Based Compensation - Options and RSU Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>41005 - Disclosure - Stockholders' Equity and Stock-Based Compensation - Options Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensationOptionsActivityDetails</Role>
      <ShortName>Stockholders' Equity and Stock-Based Compensation - Options Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>41006 - Disclosure - Stockholders' Equity and Stock-Based Compensation - RSU activity and related information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureStockholdersEquityAndStockBasedCompensationRsuActivityAndRelatedInformationDetails</Role>
      <ShortName>Stockholders' Equity and Stock-Based Compensation - RSU activity and related information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>41101 - Disclosure - Income (Loss) Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureIncomeLossPerShareDetails</Role>
      <ShortName>Income (Loss) Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureIncomeLossPerShareTables</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>41102 - Disclosure - Income (Loss) Per Share - Schedule of antidilutive securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureIncomeLossPerShareScheduleOfAntidilutiveSecuritiesDetails</Role>
      <ShortName>Income (Loss) Per Share - Schedule of antidilutive securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureIncomeLossPerShareTables</ParentRole>
      <Position>73</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>41201 - Disclosure - Employee Benefit Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureEmployeeBenefitPlansDetails</Role>
      <ShortName>Employee Benefit Plans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureEmployeeBenefitPlans</ParentRole>
      <Position>74</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>41301 - Disclosure - Tax Receivable Agreement and Income Taxes - Tax Receivable Agreement (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureTaxReceivableAgreementAndIncomeTaxesTaxReceivableAgreementDetails</Role>
      <ShortName>Tax Receivable Agreement and Income Taxes - Tax Receivable Agreement (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>41302 - Disclosure - Tax Receivable Agreement and Income Taxes - Provision for income taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureTaxReceivableAgreementAndIncomeTaxesProvisionForIncomeTaxesDetails</Role>
      <ShortName>Tax Receivable Agreement and Income Taxes - Provision for income taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>41401 - Disclosure - Segment Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureSegmentInformationDetails</Role>
      <ShortName>Segment Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureSegmentInformationTables</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>41402 - Disclosure - Segment Information - Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureSegmentInformationRevenueDetails</Role>
      <ShortName>Segment Information - Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>41403 - Disclosure - Segment Information - Operating Income (Loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureSegmentInformationOperatingIncomeLossDetails</Role>
      <ShortName>Segment Information - Operating Income (Loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>41404 - Disclosure - Segment Information - Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureSegmentInformationAssetsDetails</Role>
      <ShortName>Segment Information - Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="tmb-20230630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>41501 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.directdigitalholdings.com/role/DisclosureSubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.directdigitalholdings.com/role/DisclosureSubsequentEvents</ParentRole>
      <Position>81</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">[dq-0542-Deprecated-Concept] Concept DueToRelatedPartiesCurrent in us-gaap/2022 used in 2 facts was deprecated in us-gaap/2023 as of 2023 and should not be used. tmb-20230630x10q.htm 11</Log>
    <Log type="Warning">[dq-0542-Deprecated-Concept] Concept LondonInterbankOfferedRateLIBORMember in us-gaap/2022 used in 3 facts was deprecated in us-gaap/2023 as of 2023 and should not be used. tmb-20230630x10q.htm 23, 24</Log>
    <Log type="Warning">[dq-0542-Deprecated-Concept] Concept DueToRelatedPartiesCurrentAndNoncurrent in us-gaap/2022 used in 2 facts was deprecated in us-gaap/2023 as of 2023 and should not be used. tmb-20230630x10q.htm 26</Log>
    <Log type="Warning">[ix-0514-Hidden-Fact-Eligible-For-Transform] WARN: 20 fact(s) appearing in ix:hidden were eligible for transformation: us-gaap:CommonStockSharesIssued, us-gaap:CommonStockSharesOutstanding, us-gaap:DebtInstrumentDecreaseForgiveness, us-gaap:EarningsPerShareDiluted, us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted, us-gaap:PropertyPlantAndEquipmentUsefulLife, us-gaap:RelatedPartyTransactionAmountsOfTransaction -  tmb-20230630x10q.htm 9</Log>
    <Log type="Warning">[ix-0514-Hidden-Fact-Not-Referenced] WARN: 2 fact(s) appearing in ix:hidden were not referenced by any -sec-ix-hidden style property: us-gaap:CommitmentsAndContingencies -  tmb-20230630x10q.htm 9</Log>
  </Logs>
  <InputFiles>
    <File doctype="10-Q" original="tmb-20230630x10q.htm">tmb-20230630x10q.htm</File>
    <File>tmb-20230630.xsd</File>
    <File>tmb-20230630_cal.xml</File>
    <File>tmb-20230630_def.xml</File>
    <File>tmb-20230630_lab.xml</File>
    <File>tmb-20230630_pre.xml</File>
    <File>tmb-20230630xex31d1.htm</File>
    <File>tmb-20230630xex31d2.htm</File>
    <File>tmb-20230630xex32d1.htm</File>
    <File>tmb-20230630xex32d2.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="744">http://fasb.org/us-gaap/2022</BaseTaxonomy>
    <BaseTaxonomy items="35">http://xbrl.sec.gov/dei/2022</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
