<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.21.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>418</ContextCount>
  <ElementCount>407</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>102</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001001 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/DocumentandEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001002 - Statement - Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/BalanceSheets</Role>
      <ShortName>Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002003 - Statement - Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/BalanceSheetsParenthetical</Role>
      <ShortName>Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1003004 - Statement - Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StatementsofOperations</Role>
      <ShortName>Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1004005 - Statement - Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StatementsofComprehensiveIncome</Role>
      <ShortName>Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1005006 - Statement - Statements of Comprehensive Income (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StatementsofComprehensiveIncomeParenthetical</Role>
      <ShortName>Statements of Comprehensive Income (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1006007 - Statement - Statements of Changes in Stockholder's Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StatementsofChangesinStockholdersEquity</Role>
      <ShortName>Statements of Changes in Stockholder's Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>1007008 - Statement - Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StatementsofCashFlows</Role>
      <ShortName>Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2101101 - Disclosure - Nature of Operations and Items Impacting Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/NatureofOperationsandItemsImpactingBasisofPresentation</Role>
      <ShortName>Nature of Operations and Items Impacting Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2105102 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/SummaryofSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2110103 - Disclosure - Allowance For Credit Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/AllowanceForCreditLosses</Role>
      <ShortName>Allowance For Credit Losses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2115104 - Disclosure - Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/Investments</Role>
      <ShortName>Investments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2128105 - Disclosure - Fair Value Disclosures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/FairValueDisclosures</Role>
      <ShortName>Fair Value Disclosures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2134106 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2139107 - Disclosure - Stockholder's Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StockholdersEquity</Role>
      <ShortName>Stockholder's Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2141108 - Disclosure - Statutory Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StatutoryInformation</Role>
      <ShortName>Statutory Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2145109 - Disclosure - Reinsurance</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/Reinsurance</Role>
      <ShortName>Reinsurance</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2153110 - Disclosure - Reserves</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/Reserves</Role>
      <ShortName>Reserves</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2157111 - Disclosure - Accumulated Other Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/AccumulatedOtherComprehensiveIncome</Role>
      <ShortName>Accumulated Other Comprehensive Income</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2161112 - Disclosure - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/RelatedPartyTransactions</Role>
      <ShortName>Related Party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2163113 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2164114 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/SubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2165115 - Disclosure - Schedule I - Summary of Investments Other-Than-Investments in Related Parties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ScheduleISummaryofInvestmentsOtherThanInvestmentsinRelatedParties</Role>
      <ShortName>Schedule I - Summary of Investments Other-Than-Investments in Related Parties</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2167116 - Disclosure - Schedule III - Supplementary Insurance Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ScheduleIIISupplementaryInsuranceInformation</Role>
      <ShortName>Schedule III - Supplementary Insurance Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2169117 - Disclosure - Schedule IV - Reinsurance</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ScheduleIVReinsurance</Role>
      <ShortName>Schedule IV - Reinsurance</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2171118 - Disclosure - Schedule V - Valuation and Qualifying Accounts</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ScheduleVValuationandQualifyingAccounts</Role>
      <ShortName>Schedule V - Valuation and Qualifying Accounts</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2206201 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/SummaryofSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/SummaryofSignificantAccountingPolicies</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2302301 - Disclosure - Nature of Operations and Items Impacting Basis of Presentation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/NatureofOperationsandItemsImpactingBasisofPresentationTables</Role>
      <ShortName>Nature of Operations and Items Impacting Basis of Presentation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/NatureofOperationsandItemsImpactingBasisofPresentation</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2307302 - Disclosure - Summary of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/SummaryofSignificantAccountingPoliciesTables</Role>
      <ShortName>Summary of Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/SummaryofSignificantAccountingPolicies</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2311303 - Disclosure - Allowance For Credit Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/AllowanceForCreditLossesTables</Role>
      <ShortName>Allowance For Credit Losses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/AllowanceForCreditLosses</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2316304 - Disclosure - Investments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsTables</Role>
      <ShortName>Investments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/Investments</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2329305 - Disclosure - Fair Value Disclosures (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/FairValueDisclosuresTables</Role>
      <ShortName>Fair Value Disclosures (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/FairValueDisclosures</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2335306 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/IncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/IncomeTaxes</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2342307 - Disclosure - Statutory Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StatutoryInformationTables</Role>
      <ShortName>Statutory Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/StatutoryInformation</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2346308 - Disclosure - Reinsurance (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReinsuranceTables</Role>
      <ShortName>Reinsurance (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/Reinsurance</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2354309 - Disclosure - Reserves (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReservesTables</Role>
      <ShortName>Reserves (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/Reserves</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2358310 - Disclosure - Accumulated Other Comprehensive Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/AccumulatedOtherComprehensiveIncomeTables</Role>
      <ShortName>Accumulated Other Comprehensive Income (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/AccumulatedOtherComprehensiveIncome</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2403401 - Disclosure - Nature of Operations and Items Impacting Basis of Presentation - Gain by Transaction Component (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/NatureofOperationsandItemsImpactingBasisofPresentationGainbyTransactionComponentDetails</Role>
      <ShortName>Nature of Operations and Items Impacting Basis of Presentation - Gain by Transaction Component (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2404402 - Disclosure - Nature of Operations and Items Impacting Basis of Presentation - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/NatureofOperationsandItemsImpactingBasisofPresentationNarrativeDetails</Role>
      <ShortName>Nature of Operations and Items Impacting Basis of Presentation - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/NatureofOperationsandItemsImpactingBasisofPresentationTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2408403 - Disclosure - Summary of Significant Accounting Policies - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2409404 - Disclosure - Summary of Significant Accounting Policies - Reserve Information For Major Product Lines (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/SummaryofSignificantAccountingPoliciesReserveInformationForMajorProductLinesDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Reserve Information For Major Product Lines (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2412405 - Disclosure - Allowance For Credit Losses - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/AllowanceForCreditLossesNarrativeDetails</Role>
      <ShortName>Allowance For Credit Losses - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2413406 - Disclosure - Allowance For Credit Losses - Impact of Adoption (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/AllowanceForCreditLossesImpactofAdoptionDetails</Role>
      <ShortName>Allowance For Credit Losses - Impact of Adoption (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2414407 - Disclosure - Allowance For Credit Losses - Changes in CECL Allowance for Reinsurance Recoverables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/AllowanceForCreditLossesChangesinCECLAllowanceforReinsuranceRecoverablesDetails</Role>
      <ShortName>Allowance For Credit Losses - Changes in CECL Allowance for Reinsurance Recoverables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2417408 - Disclosure - Investments - Schedule of Amortized Cost, Gross Unrealized Gains and Losses, Fair Value, and Other-Than-Temporary-Impairment of Fixed Maturity and Equity Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsScheduleofAmortizedCostGrossUnrealizedGainsandLossesFairValueandOtherThanTemporaryImpairmentofFixedMaturityandEquitySecuritiesDetails</Role>
      <ShortName>Investments - Schedule of Amortized Cost, Gross Unrealized Gains and Losses, Fair Value, and Other-Than-Temporary-Impairment of Fixed Maturity and Equity Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2418409 - Disclosure - Investments - Schedule of Amortized Cost, Gross Unrealized Gains and Losses, Fair Value, and Other-Than-Temporary-Impairment of Fixed Maturity and Equity Securities - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsScheduleofAmortizedCostGrossUnrealizedGainsandLossesFairValueandOtherThanTemporaryImpairmentofFixedMaturityandEquitySecuritiesNarrativeDetails</Role>
      <ShortName>Investments - Schedule of Amortized Cost, Gross Unrealized Gains and Losses, Fair Value, and Other-Than-Temporary-Impairment of Fixed Maturity and Equity Securities - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2419410 - Disclosure - Investments - Schedule of Cost or Amortized Cost and Fair Value of Fixed Maturity Securities By Contractual Maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsScheduleofCostorAmortizedCostandFairValueofFixedMaturitySecuritiesByContractualMaturityDetails</Role>
      <ShortName>Investments - Schedule of Cost or Amortized Cost and Fair Value of Fixed Maturity Securities By Contractual Maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2420411 - Disclosure - Investments - Schedule of Major Categories of Net Investment Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsScheduleofMajorCategoriesofNetInvestmentIncomeDetails</Role>
      <ShortName>Investments - Schedule of Major Categories of Net Investment Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>2421412 - Disclosure - Investments - Proceeds From Sales of Available-For-Sale Securities and the Gross Realized Gains and Gross Realized Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsProceedsFromSalesofAvailableForSaleSecuritiesandtheGrossRealizedGainsandGrossRealizedLossesDetails</Role>
      <ShortName>Investments - Proceeds From Sales of Available-For-Sale Securities and the Gross Realized Gains and Gross Realized Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>2422413 - Disclosure - Investments - Schedule of Net Realized Gains (Losses), Including Other-Than-Temporary Impairments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsScheduleofNetRealizedGainsLossesIncludingOtherThanTemporaryImpairmentsDetails</Role>
      <ShortName>Investments - Schedule of Net Realized Gains (Losses), Including Other-Than-Temporary Impairments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>2423414 - Disclosure - Investments - Schedule of Net Unrealized Losses on Equity Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsScheduleofNetUnrealizedLossesonEquitySecuritiesDetails</Role>
      <ShortName>Investments - Schedule of Net Unrealized Losses on Equity Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>2424415 - Disclosure - Investments - Schedule of Gross Unrealized Losses on Fixed Maturity Securities and Equity Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsScheduleofGrossUnrealizedLossesonFixedMaturitySecuritiesandEquitySecuritiesDetails</Role>
      <ShortName>Investments - Schedule of Gross Unrealized Losses on Fixed Maturity Securities and Equity Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>2425416 - Disclosure - Investments - Schedule of Cost or Amortized Cost and Fair Value of Available-For-Sale Fixed Maturity Securities in an Unrealized Loss Position (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsScheduleofCostorAmortizedCostandFairValueofAvailableForSaleFixedMaturitySecuritiesinanUnrealizedLossPositionDetails</Role>
      <ShortName>Investments - Schedule of Cost or Amortized Cost and Fair Value of Available-For-Sale Fixed Maturity Securities in an Unrealized Loss Position (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>2426417 - Disclosure - Investments - Summary of Loan-To-Value and Average Debt-Service Coverage Ratios (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsSummaryofLoanToValueandAverageDebtServiceCoverageRatiosDetails</Role>
      <ShortName>Investments - Summary of Loan-To-Value and Average Debt-Service Coverage Ratios (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>2427418 - Disclosure - Investments - Variable Interest Entities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/InvestmentsVariableInterestEntitiesDetails</Role>
      <ShortName>Investments - Variable Interest Entities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>2430419 - Disclosure - Fair Value Disclosures - Schedule of the Company's Fair Value Hierarchy for Recurring Basis Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/FairValueDisclosuresScheduleoftheCompanysFairValueHierarchyforRecurringBasisAssetsandLiabilitiesDetails</Role>
      <ShortName>Fair Value Disclosures - Schedule of the Company's Fair Value Hierarchy for Recurring Basis Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>2431420 - Disclosure - Fair Value Disclosures - Summary of the Change in Balance Sheet Carrying Value Associated with Level 3 Financial Assets Carried at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/FairValueDisclosuresSummaryoftheChangeinBalanceSheetCarryingValueAssociatedwithLevel3FinancialAssetsCarriedatFairValueDetails</Role>
      <ShortName>Fair Value Disclosures - Summary of the Change in Balance Sheet Carrying Value Associated with Level 3 Financial Assets Carried at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>2432421 - Disclosure - Fair Value Disclosures - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/FairValueDisclosuresNarrativeDetails</Role>
      <ShortName>Fair Value Disclosures - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>2433422 - Disclosure - Fair Value Disclosures - Schedule of Carrying Value, Fair Value Amount and Hierarchy Level of the Financial Instruments That Are Not Recognized or Are Not Carried at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/FairValueDisclosuresScheduleofCarryingValueFairValueAmountandHierarchyLeveloftheFinancialInstrumentsThatAreNotRecognizedorAreNotCarriedatFairValueDetails</Role>
      <ShortName>Fair Value Disclosures - Schedule of Carrying Value, Fair Value Amount and Hierarchy Level of the Financial Instruments That Are Not Recognized or Are Not Carried at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>2436423 - Disclosure - Income Taxes Income Taxes - Schedule of Company's Current and Deferred Federal Tax Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/IncomeTaxesIncomeTaxesScheduleofCompanysCurrentandDeferredFederalTaxExpenseDetails</Role>
      <ShortName>Income Taxes Income Taxes - Schedule of Company's Current and Deferred Federal Tax Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>2437424 - Disclosure - Income Taxes - Schedule of Reconciliation of the Federal Income Tax Rate to the Company's Effective Income Tax Rate (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/IncomeTaxesScheduleofReconciliationoftheFederalIncomeTaxRatetotheCompanysEffectiveIncomeTaxRateDetails</Role>
      <ShortName>Income Taxes - Schedule of Reconciliation of the Federal Income Tax Rate to the Company's Effective Income Tax Rate (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>2438425 - Disclosure - Income Taxes - Schedule of Significant Deferred Tax Assets and Deferred Tax Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/IncomeTaxesScheduleofSignificantDeferredTaxAssetsandDeferredTaxLiabilitiesDetails</Role>
      <ShortName>Income Taxes - Schedule of Significant Deferred Tax Assets and Deferred Tax Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>2440426 - Disclosure - Stockholder's Equity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StockholdersEquityDetails</Role>
      <ShortName>Stockholder's Equity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/StockholdersEquity</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>2443427 - Disclosure - Statutory Information - Schedule of Statutory Net Income and Capital and Surplus (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StatutoryInformationScheduleofStatutoryNetIncomeandCapitalandSurplusDetails</Role>
      <ShortName>Statutory Information - Schedule of Statutory Net Income and Capital and Surplus (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>2444428 - Disclosure - Statutory Information - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/StatutoryInformationNarrativeDetails</Role>
      <ShortName>Statutory Information - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>2447429 - Disclosure - Reinsurance - Schedule of Reinsurance Recoverables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReinsuranceScheduleofReinsuranceRecoverablesDetails</Role>
      <ShortName>Reinsurance - Schedule of Reinsurance Recoverables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>2448430 - Disclosure - Reinsurance - Schedule of Reinsurance Recoverables by A.M. Best Rating (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReinsuranceScheduleofReinsuranceRecoverablesbyAMBestRatingDetails</Role>
      <ShortName>Reinsurance - Schedule of Reinsurance Recoverables by A.M. Best Rating (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>2449431 - Disclosure - Reinsurance - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReinsuranceNarrativeDetails</Role>
      <ShortName>Reinsurance - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>2450432 - Disclosure - Reinsurance Reinsurance - Schedule of Reinsurance Recoverable by Reinsurer (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReinsuranceReinsuranceScheduleofReinsuranceRecoverablebyReinsurerDetails</Role>
      <ShortName>Reinsurance Reinsurance - Schedule of Reinsurance Recoverable by Reinsurer (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>2451433 - Disclosure - Reinsurance Reinsurance - Reinsurance Recoverables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReinsuranceReinsuranceReinsuranceRecoverablesDetails</Role>
      <ShortName>Reinsurance Reinsurance - Reinsurance Recoverables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>2452434 - Disclosure - Reinsurance - Schedule of Effect of Reinsurance on Premiums Earned and Benefits Incurred (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReinsuranceScheduleofEffectofReinsuranceonPremiumsEarnedandBenefitsIncurredDetails</Role>
      <ShortName>Reinsurance - Schedule of Effect of Reinsurance on Premiums Earned and Benefits Incurred (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>2455435 - Disclosure - Reserves - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReservesNarrativeDetails</Role>
      <ShortName>Reserves - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>2456436 - Disclosure - Reserves - Schedule of Most Significant Claims and Benefits Payable (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ReservesScheduleofMostSignificantClaimsandBenefitsPayableDetails</Role>
      <ShortName>Reserves - Schedule of Most Significant Claims and Benefits Payable (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>2459437 - Disclosure - Accumulated Other Comprehensive Income - Schedule of Components of Accumulated Other Comprehensive Income, Net of Tax (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/AccumulatedOtherComprehensiveIncomeScheduleofComponentsofAccumulatedOtherComprehensiveIncomeNetofTaxDetails</Role>
      <ShortName>Accumulated Other Comprehensive Income - Schedule of Components of Accumulated Other Comprehensive Income, Net of Tax (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>2460438 - Disclosure - Accumulated Other Comprehensive Income - Summary of the Reclassifications Out of Accumulated Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/AccumulatedOtherComprehensiveIncomeSummaryoftheReclassificationsOutofAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Accumulated Other Comprehensive Income - Summary of the Reclassifications Out of Accumulated Other Comprehensive Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>2462439 - Disclosure - Related Party Transactions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/RelatedPartyTransactionsDetails</Role>
      <ShortName>Related Party Transactions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/RelatedPartyTransactions</ParentRole>
      <Position>76</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>2466440 - Disclosure - Schedule I - Summary of Investments Other-Than-Investments in Related Parties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ScheduleISummaryofInvestmentsOtherThanInvestmentsinRelatedPartiesDetails</Role>
      <ShortName>Schedule I - Summary of Investments Other-Than-Investments in Related Parties (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/ScheduleISummaryofInvestmentsOtherThanInvestmentsinRelatedParties</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>2468441 - Disclosure - Schedule III-Supplementary Insurance Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ScheduleIIISupplementaryInsuranceInformationDetails</Role>
      <ShortName>Schedule III-Supplementary Insurance Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>2470442 - Disclosure - Schedule IV - Reinsurance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ScheduleIVReinsuranceDetails</Role>
      <ShortName>Schedule IV - Reinsurance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/ScheduleIVReinsurance</ParentRole>
      <Position>79</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>2472443 - Disclosure - Schedule V - Valuation and Qualifying Accounts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://talcottresolution.com/role/ScheduleVValuationandQualifyingAccountsDetails</Role>
      <ShortName>Schedule V - Valuation and Qualifying Accounts (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://talcottresolution.com/role/ScheduleVValuationandQualifyingAccounts</ParentRole>
      <Position>80</Position>
    </Report>
    <Report instance="tl-20210415.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9999.htm</HtmlFileName>
      <LongName>Uncategorized Items - tl-20210415.htm</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/role/uncategorizedFacts</Role>
      <ShortName>Uncategorized Items - tl-20210415.htm</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>81</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="S-1" original="tl-20210415.htm">tl-20210415.htm</File>
    <File>a224347consentex9923b1next.htm</File>
    <File>a224347opinionex9951nextgen.htm</File>
    <File>ex9921ususls-11nextgen.htm</File>
    <File>ex9924usicpoas11nextgen.htm</File>
    <File>tl-20210415.xsd</File>
    <File>tl-20210415_cal.xml</File>
    <File>tl-20210415_def.xml</File>
    <File>tl-20210415_lab.xml</File>
    <File>tl-20210415_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>tl-20210415_g1.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy>http://fasb.org/us-gaap/2020-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/srt/2020-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2020-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/country/2020-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/stpr/2018-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
