<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.24.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>448</ContextCount>
  <ElementCount>421</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>105</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>8</UnitCount>
  <MyReports>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0000002 - Document - Audit Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/AuditInformation</Role>
      <ShortName>Audit Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0000003 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0000004 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0000005 - Statement - Consolidated Statements of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ConsolidatedStatementsofIncome</Role>
      <ShortName>Consolidated Statements of Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>0000006 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ConsolidatedStatementsofComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>0000007 - Statement - Consolidated Statements of Changes in Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ConsolidatedStatementsofChangesinEquity</Role>
      <ShortName>Consolidated Statements of Changes in Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>0000008 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ConsolidatedStatementsofCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>0000009 - Disclosure - Nature of business and organization structure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Natureofbusinessandorganizationstructure</Role>
      <ShortName>Nature of business and organization structure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>0000010 - Disclosure - Summary of significant accounting policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Summaryofsignificantaccountingpolicies</Role>
      <ShortName>Summary of significant accounting policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>0000011 - Disclosure - Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Investments</Role>
      <ShortName>Investments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>0000012 - Disclosure - Fair Value</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/FairValue</Role>
      <ShortName>Fair Value</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>0000013 - Disclosure - Loss Reserves</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/LossReserves</Role>
      <ShortName>Loss Reserves</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>0000014 - Disclosure - Reinsurance</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Reinsurance</Role>
      <ShortName>Reinsurance</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>0000015 - Disclosure - Borrowings</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Borrowings</Role>
      <ShortName>Borrowings</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>0000016 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>0000017 - Disclosure - Employee benefits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Employeebenefits</Role>
      <ShortName>Employee benefits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>0000018 - Disclosure - Share-based compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Sharebasedcompensation</Role>
      <ShortName>Share-based compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>0000019 - Disclosure - Related party transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Relatedpartytransactions</Role>
      <ShortName>Related party transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>0000020 - Disclosure - Commitments and contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/Commitmentsandcontingencies</Role>
      <ShortName>Commitments and contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>0000021 - Disclosure - Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/StockholdersEquity</Role>
      <ShortName>Stockholders' Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>0000022 - Disclosure - Accumulated Other Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/AccumulatedOtherComprehensiveIncomeLoss</Role>
      <ShortName>Accumulated Other Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>0000023 - Disclosure - Statutory Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/StatutoryInformation</Role>
      <ShortName>Statutory Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>0000024 - Disclosure - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/EarningsPerShare</Role>
      <ShortName>Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>0000025 - Disclosure - Schedule I, Summary of Investments - Other than Investments in Related Parties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleISummaryofInvestmentsOtherthanInvestmentsinRelatedParties</Role>
      <ShortName>Schedule I, Summary of Investments - Other than Investments in Related Parties</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>0000026 - Disclosure - Schedule II - Parent Company Only</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleIIParentCompanyOnly</Role>
      <ShortName>Schedule II - Parent Company Only</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9954471 - Disclosure - Summary of significant accounting policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/SummaryofsignificantaccountingpoliciesPolicies</Role>
      <ShortName>Summary of significant accounting policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9954472 - Disclosure - Investments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/InvestmentsTables</Role>
      <ShortName>Investments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/Investments</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9954473 - Disclosure - Fair Value (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/FairValueTables</Role>
      <ShortName>Fair Value (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/FairValue</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9954474 - Disclosure - Loss Reserves (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/LossReservesTables</Role>
      <ShortName>Loss Reserves (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/LossReserves</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9954475 - Disclosure - Reinsurance (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ReinsuranceTables</Role>
      <ShortName>Reinsurance (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/Reinsurance</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9954476 - Disclosure - Borrowings (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/BorrowingsTables</Role>
      <ShortName>Borrowings (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/Borrowings</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9954477 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/IncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/IncomeTaxes</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9954478 - Disclosure - Share-based compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/SharebasedcompensationTables</Role>
      <ShortName>Share-based compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/Sharebasedcompensation</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9954479 - Disclosure - Related party transactions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/RelatedpartytransactionsTables</Role>
      <ShortName>Related party transactions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/Relatedpartytransactions</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9954480 - Disclosure - Commitments and contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/CommitmentsandcontingenciesTables</Role>
      <ShortName>Commitments and contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/Commitmentsandcontingencies</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9954481 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/AccumulatedOtherComprehensiveIncomeLossTables</Role>
      <ShortName>Accumulated Other Comprehensive Income (Loss) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/AccumulatedOtherComprehensiveIncomeLoss</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9954482 - Disclosure - Statutory Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/StatutoryInformationTables</Role>
      <ShortName>Statutory Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/StatutoryInformation</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9954483 - Disclosure - Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/EarningsPerShareTables</Role>
      <ShortName>Earnings Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/EarningsPerShare</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9954484 - Disclosure - Schedule II - Parent Company Only (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleIIParentCompanyOnlyTables</Role>
      <ShortName>Schedule II - Parent Company Only (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/ScheduleIIParentCompanyOnly</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9954485 - Disclosure - Nature of business and organization structure (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/NatureofbusinessandorganizationstructureDetails</Role>
      <ShortName>Nature of business and organization structure (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/Natureofbusinessandorganizationstructure</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9954486 - Disclosure - Summary of significant accounting policies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/SummaryofsignificantaccountingpoliciesDetails</Role>
      <ShortName>Summary of significant accounting policies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/SummaryofsignificantaccountingpoliciesPolicies</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9954487 - Disclosure - Investments - Net Investment Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/InvestmentsNetInvestmentIncomeDetails</Role>
      <ShortName>Investments - Net Investment Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9954488 - Disclosure - Investments - Net Investment Gains (Losses) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/InvestmentsNetInvestmentGainsLossesDetails</Role>
      <ShortName>Investments - Net Investment Gains (Losses) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9954489 - Disclosure - Investments - Net Unrealized Gains and Losses on Available-for-Sale Securities as a Separate Component of OCI (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/InvestmentsNetUnrealizedGainsandLossesonAvailableforSaleSecuritiesasaSeparateComponentofOCIDetails</Role>
      <ShortName>Investments - Net Unrealized Gains and Losses on Available-for-Sale Securities as a Separate Component of OCI (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9954490 - Disclosure - Investments - Change in Net Unrealized Gains (Losses) on Available-for-Sale Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/InvestmentsChangeinNetUnrealizedGainsLossesonAvailableforSaleSecuritiesDetails</Role>
      <ShortName>Investments - Change in Net Unrealized Gains (Losses) on Available-for-Sale Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9954491 - Disclosure - Investments - Summary of Fixed Maturity Securities Classified as Available-for-Sale (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/InvestmentsSummaryofFixedMaturitySecuritiesClassifiedasAvailableforSaleDetails</Role>
      <ShortName>Investments - Summary of Fixed Maturity Securities Classified as Available-for-Sale (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9954492 - Disclosure - Investments - Schedule of Fixed Maturity Securities in an Continuous Unrealized Loss Position (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/InvestmentsScheduleofFixedMaturitySecuritiesinanContinuousUnrealizedLossPositionDetails</Role>
      <ShortName>Investments - Schedule of Fixed Maturity Securities in an Continuous Unrealized Loss Position (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>9954493 - Disclosure - Investments - Summary of Contractual Maturities of Fixed Maturity Securities Available-For-Sale (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/InvestmentsSummaryofContractualMaturitiesofFixedMaturitySecuritiesAvailableForSaleDetails</Role>
      <ShortName>Investments - Summary of Contractual Maturities of Fixed Maturity Securities Available-For-Sale (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>9954494 - Disclosure - Investments - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/InvestmentsNarrativeDetails</Role>
      <ShortName>Investments - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>9954495 - Disclosure - Fair Value - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/FairValueNarrativeDetails</Role>
      <ShortName>Fair Value - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>9954496 - Disclosure - Fair Value - Summary of Significant Inputs used for Fair Value Measurement of Fixed Maturity Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/FairValueSummaryofSignificantInputsusedforFairValueMeasurementofFixedMaturitySecuritiesDetails</Role>
      <ShortName>Fair Value - Summary of Significant Inputs used for Fair Value Measurement of Fixed Maturity Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>9954497 - Disclosure - Fair Value - Schedule of Fair Value Assets Measured on Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/FairValueScheduleofFairValueAssetsMeasuredonRecurringBasisDetails</Role>
      <ShortName>Fair Value - Schedule of Fair Value Assets Measured on Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>9954498 - Disclosure - Fair Value - Schedule of Additional Information about Fair Value Assets Measured on Recurring Basis, Unobservable Input Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/FairValueScheduleofAdditionalInformationaboutFairValueAssetsMeasuredonRecurringBasisUnobservableInputReconciliationDetails</Role>
      <ShortName>Fair Value - Schedule of Additional Information about Fair Value Assets Measured on Recurring Basis, Unobservable Input Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>9954499 - Disclosure - Fair Value - Summary of Fair Value Assets Measured on Recurring Basis, Significant Unobservable Input (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/FairValueSummaryofFairValueAssetsMeasuredonRecurringBasisSignificantUnobservableInputDetails</Role>
      <ShortName>Fair Value - Summary of Fair Value Assets Measured on Recurring Basis, Significant Unobservable Input (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>9954500 - Disclosure - Fair Value - Schedule of Estimated Fair Value Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/FairValueScheduleofEstimatedFairValueLiabilitiesDetails</Role>
      <ShortName>Fair Value - Schedule of Estimated Fair Value Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>9954501 - Disclosure - Loss Reserves - Activity for the Liability for Loss Reserves (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/LossReservesActivityfortheLiabilityforLossReservesDetails</Role>
      <ShortName>Loss Reserves - Activity for the Liability for Loss Reserves (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>9954502 - Disclosure - Loss Reserves - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/LossReservesNarrativeDetails</Role>
      <ShortName>Loss Reserves - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>9954503 - Disclosure - Loss Reserves - IBNR Liabilities and Expected Development on Reported Claims (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/LossReservesIBNRLiabilitiesandExpectedDevelopmentonReportedClaimsDetails</Role>
      <ShortName>Loss Reserves - IBNR Liabilities and Expected Development on Reported Claims (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>9954504 - Disclosure - Loss Reserves - Paid Claims Development, Net of Reinsurance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/LossReservesPaidClaimsDevelopmentNetofReinsuranceDetails</Role>
      <ShortName>Loss Reserves - Paid Claims Development, Net of Reinsurance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>9954505 - Disclosure - Loss Reserves - Average Payout of Incurred Claims by Age (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/LossReservesAveragePayoutofIncurredClaimsbyAgeDetails</Role>
      <ShortName>Loss Reserves - Average Payout of Incurred Claims by Age (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>9954506 - Disclosure - Reinsurance - Summary of Effects of Reinsurance on Premiums Written and Earned (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ReinsuranceSummaryofEffectsofReinsuranceonPremiumsWrittenandEarnedDetails</Role>
      <ShortName>Reinsurance - Summary of Effects of Reinsurance on Premiums Written and Earned (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>9954507 - Disclosure - Reinsurance - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ReinsuranceNarrativeDetails</Role>
      <ShortName>Reinsurance - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>9954508 - Disclosure - Reinsurance - Schedule of Retained Aggregate Loss and Initial and Current Reinsurance Coverage (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ReinsuranceScheduleofRetainedAggregateLossandInitialandCurrentReinsuranceCoverageDetails</Role>
      <ShortName>Reinsurance - Schedule of Retained Aggregate Loss and Initial and Current Reinsurance Coverage (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>9954509 - Disclosure - Reinsurance - Quota Share Reinsurance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ReinsuranceQuotaShareReinsuranceDetails</Role>
      <ShortName>Reinsurance - Quota Share Reinsurance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>9954510 - Disclosure - Borrowings - Schedule of Long-term Borrowings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/BorrowingsScheduleofLongtermBorrowingsDetails</Role>
      <ShortName>Borrowings - Schedule of Long-term Borrowings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>9954511 - Disclosure - Borrowings - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/BorrowingsNarrativeDetails</Role>
      <ShortName>Borrowings - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>9954512 - Disclosure - Income Taxes - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/IncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>9954513 - Disclosure - Income Taxes - Provision for Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/IncomeTaxesProvisionforIncomeTaxesDetails</Role>
      <ShortName>Income Taxes - Provision for Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>9954514 - Disclosure - Income Taxes - Tax Rate Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/IncomeTaxesTaxRateReconciliationDetails</Role>
      <ShortName>Income Taxes - Tax Rate Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>9954515 - Disclosure - Income Taxes - Deferred Tax Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/IncomeTaxesDeferredTaxAssetsandLiabilitiesDetails</Role>
      <ShortName>Income Taxes - Deferred Tax Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>9954516 - Disclosure - Employee benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/EmployeebenefitsDetails</Role>
      <ShortName>Employee benefits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/Employeebenefits</ParentRole>
      <Position>73</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>9954517 - Disclosure - Share-based compensation - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/SharebasedcompensationNarrativeDetails</Role>
      <ShortName>Share-based compensation - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>9954518 - Disclosure - Share-based compensation - Status of EHI Equity Based Awards (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/SharebasedcompensationStatusofEHIEquityBasedAwardsDetails</Role>
      <ShortName>Share-based compensation - Status of EHI Equity Based Awards (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>9954519 - Disclosure - Share-based compensation - Cash Award Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/SharebasedcompensationCashAwardActivityDetails</Role>
      <ShortName>Share-based compensation - Cash Award Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>9954520 - Disclosure - Share-based compensation - Status of Other Equity Based Awards (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/SharebasedcompensationStatusofOtherEquityBasedAwardsDetails</Role>
      <ShortName>Share-based compensation - Status of Other Equity Based Awards (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>9954521 - Disclosure - Related party transactions - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/RelatedpartytransactionsNarrativeDetails</Role>
      <ShortName>Related party transactions - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>9954522 - Disclosure - Related party transactions - Schedule of Related Party Transactions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/RelatedpartytransactionsScheduleofRelatedPartyTransactionsDetails</Role>
      <ShortName>Related party transactions - Schedule of Related Party Transactions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>9954523 - Disclosure - Commitments and contingencies - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/CommitmentsandcontingenciesNarrativeDetails</Role>
      <ShortName>Commitments and contingencies - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>9954524 - Disclosure - Commitments and contingencies - Operating Lease Maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/CommitmentsandcontingenciesOperatingLeaseMaturityDetails</Role>
      <ShortName>Commitments and contingencies - Operating Lease Maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>9954525 - Disclosure - Stockholders' Equity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/StockholdersEquityDetails</Role>
      <ShortName>Stockholders' Equity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/StockholdersEquity</ParentRole>
      <Position>82</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>9954526 - Disclosure - Accumulated Other Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/AccumulatedOtherComprehensiveIncomeLossScheduleofAccumulatedOtherComprehensiveIncomeLossDetails</Role>
      <ShortName>Accumulated Other Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/AccumulatedOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>83</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>9954527 - Disclosure - Accumulated Other Comprehensive Income (Loss) - Reclassification out of Accumulated Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/AccumulatedOtherComprehensiveIncomeLossReclassificationoutofAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Accumulated Other Comprehensive Income (Loss) - Reclassification out of Accumulated Other Comprehensive Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/AccumulatedOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>84</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>9954528 - Disclosure - Statutory Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/StatutoryInformationDetails</Role>
      <ShortName>Statutory Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/StatutoryInformationTables</ParentRole>
      <Position>85</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>9954529 - Disclosure - Statutory Information - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/StatutoryInformationNarrativeDetails</Role>
      <ShortName>Statutory Information - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>9954530 - Disclosure - Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/EarningsPerShareDetails</Role>
      <ShortName>Earnings Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/EarningsPerShareTables</ParentRole>
      <Position>87</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>9954531 - Disclosure - Schedule I, Summary of Investments - Other than Investments in Related Parties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleISummaryofInvestmentsOtherthanInvestmentsinRelatedPartiesDetails</Role>
      <ShortName>Schedule I, Summary of Investments - Other than Investments in Related Parties (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://ir.enactmi.com/role/ScheduleISummaryofInvestmentsOtherthanInvestmentsinRelatedParties</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>9954532 - Disclosure - Schedule II - Parent Company Only - Balance Sheet (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleIIParentCompanyOnlyBalanceSheetDetails</Role>
      <ShortName>Schedule II - Parent Company Only - Balance Sheet (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>9954533 - Disclosure - Schedule II - Parent Company Only - Statements of Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleIIParentCompanyOnlyStatementsofIncomeDetails</Role>
      <ShortName>Schedule II - Parent Company Only - Statements of Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>9954534 - Disclosure - Schedule II - Parent Company Only - Statements of Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleIIParentCompanyOnlyStatementsofComprehensiveIncomeDetails</Role>
      <ShortName>Schedule II - Parent Company Only - Statements of Comprehensive Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>9954535 - Disclosure - Schedule II - Parent Company Only - Statements of Cash Flows (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleIIParentCompanyOnlyStatementsofCashFlowsDetails</Role>
      <ShortName>Schedule II - Parent Company Only - Statements of Cash Flows (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>9954536 - Disclosure - Schedule II - Parent Company Only - Notes to Schedule II Narrative (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleIIParentCompanyOnlyNotestoScheduleIINarrativeDetails</Role>
      <ShortName>Schedule II - Parent Company Only - Notes to Schedule II Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="act-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>9954537 - Disclosure - Schedule II - Parent Company Only - Notes to Schedule II Schedule of Borrowings (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://ir.enactmi.com/role/ScheduleIIParentCompanyOnlyNotestoScheduleIIScheduleofBorrowingsDetails</Role>
      <ShortName>Schedule II - Parent Company Only - Notes to Schedule II Schedule of Borrowings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-K" isDefinitelyFs="true" isUsgaap="true" original="act-20231231.htm">act-20231231.htm</File>
    <File>act-20231231.xsd</File>
    <File>act-20231231_cal.xml</File>
    <File>act-20231231_def.xml</File>
    <File>act-20231231_lab.xml</File>
    <File>act-20231231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>act-20231231_g1.jpg</File>
    <File>act-20231231_g2.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="5">http://fasb.org/srt/2023</BaseTaxonomy>
    <BaseTaxonomy items="1797">http://fasb.org/us-gaap/2023</BaseTaxonomy>
    <BaseTaxonomy items="38">http://xbrl.sec.gov/dei/2023</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2023</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
