<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.10.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>1148</ContextCount>
  <ElementCount>380</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>196</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001000 - Statement - Condensed Consolidated Statements of Operations (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/CondensedConsolidatedStatementsOfOperationsUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Operations (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002000 - Statement - Condensed Consolidated Statements of Comprehensive Income (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/CondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Comprehensive Income (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1003000 - Statement - Condensed Consolidated Balance Sheets (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/CondensedConsolidatedBalanceSheetsUnaudited</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1003501 - Statement - Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1004000 - Statement - Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/CondensedConsolidatedStatementsOfChangesInStockholdersEquityUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1005000 - Statement - Condensed Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/CondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - Basis of Presentation and Accounting Policies Basis of Presentation and Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/BasisOfPresentationAndAccountingPoliciesBasisOfPresentationAndSignificantAccountingPolicies</Role>
      <ShortName>Basis of Presentation and Accounting Policies Basis of Presentation and Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - Derivatives</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/Derivatives</Role>
      <ShortName>Derivatives</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - Fair Value Measurements Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2103100 - Disclosure - Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/Investments</Role>
      <ShortName>Investments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2109100 - Disclosure - Reinsurance Level 1 (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehartford.com/role/ReinsuranceLevel1Notes</Role>
      <ShortName>Reinsurance Level 1 (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2111100 - Disclosure - Deferred Policy Acquisition Costs and Value of Business Acquired Level 1 (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehartford.com/role/DeferredPolicyAcquisitionCostsAndValueOfBusinessAcquiredLevel1Notes</Role>
      <ShortName>Deferred Policy Acquisition Costs and Value of Business Acquired Level 1 (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2114100 - Disclosure - Reserve for Future Policy Benefits and SA Liabilities Level 1 (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehartford.com/role/ReserveForFuturePolicyBenefitsAndSaLiabilitiesLevel1Notes</Role>
      <ShortName>Reserve for Future Policy Benefits and SA Liabilities Level 1 (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2115100 - Disclosure - Income Taxes Level 1 (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehartford.com/role/IncomeTaxesLevel1Notes</Role>
      <ShortName>Income Taxes Level 1 (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2116100 - Disclosure - Commitments and Contingencies Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/CommitmentsAndContingenciesCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2117100 - Disclosure - Transactions with Affiliates Level 1 (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehartford.com/role/TransactionsWithAffiliatesLevel1Notes</Role>
      <ShortName>Transactions with Affiliates Level 1 (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2118100 - Disclosure - Changes in and Reclassifications from Accumulated Other Comprehensive Income Changes in and Reclassifications from Accumulated Other Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ChangesInAndReclassificationsFromAccumulatedOtherComprehensiveIncomeChangesInAndReclassificationsFromAccumulatedOtherComprehensiveIncome</Role>
      <ShortName>Changes in and Reclassifications from Accumulated Other Comprehensive Income Changes in and Reclassifications from Accumulated Other Comprehensive Income</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2119100 - Disclosure - Other Intangible Assets Level 1 (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.thehartford.com/role/OtherIntangibleAssetsLevel1Notes</Role>
      <ShortName>Other Intangible Assets Level 1 (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2201201 - Disclosure - Basis of Presentation and Accounting Policies Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/BasisOfPresentationAndAccountingPoliciesSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Basis of Presentation and Accounting Policies Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/BasisOfPresentationAndAccountingPoliciesBasisOfPresentationAndSignificantAccountingPolicies</ParentRole>
      <Position>20</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2301301 - Disclosure - Derivatives (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DerivativesTables</Role>
      <ShortName>Derivatives (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/Derivatives</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2301301 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/FairValueMeasurementsFairValueMeasurements</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2301302 - Disclosure - Basis of Presentation and Accounting Policies Business Combination - Sale of HHI (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/BasisOfPresentationAndAccountingPoliciesBusinessCombinationSaleOfHhiTables</Role>
      <ShortName>Basis of Presentation and Accounting Policies Business Combination - Sale of HHI (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2303301 - Disclosure - Investments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsTables</Role>
      <ShortName>Investments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/Investments</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2309301 - Disclosure - Reinsurance Level 3 (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ReinsuranceLevel3Tables</Role>
      <ShortName>Reinsurance Level 3 (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/ReinsuranceLevel1Notes</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2311301 - Disclosure - Deferred Policy Acquisition Costs and Value of Business Acquired Level 3 (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DeferredPolicyAcquisitionCostsAndValueOfBusinessAcquiredLevel3Tables</Role>
      <ShortName>Deferred Policy Acquisition Costs and Value of Business Acquired Level 3 (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/DeferredPolicyAcquisitionCostsAndValueOfBusinessAcquiredLevel1Notes</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2314301 - Disclosure - Reserve for Future Policy Benefits and SA Liabilities Level 3 (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ReserveForFuturePolicyBenefitsAndSaLiabilitiesLevel3Tables</Role>
      <ShortName>Reserve for Future Policy Benefits and SA Liabilities Level 3 (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/ReserveForFuturePolicyBenefitsAndSaLiabilitiesLevel1Notes</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2315301 - Disclosure - Income Taxes Level 3 (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/IncomeTaxesLevel3Tables</Role>
      <ShortName>Income Taxes Level 3 (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/IncomeTaxesLevel1Notes</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2318301 - Disclosure - Changes in and Reclassifications from Accumulated Other Comprehensive Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ChangesInAndReclassificationsFromAccumulatedOtherComprehensiveIncomeTables</Role>
      <ShortName>Changes in and Reclassifications from Accumulated Other Comprehensive Income (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/ChangesInAndReclassificationsFromAccumulatedOtherComprehensiveIncomeChangesInAndReclassificationsFromAccumulatedOtherComprehensiveIncome</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2319301 - Disclosure - Other Intangible Assets Level 3 (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/OtherIntangibleAssetsLevel3Tables</Role>
      <ShortName>Other Intangible Assets Level 3 (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/OtherIntangibleAssetsLevel1Notes</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2401402 - Disclosure - Derivatives - Derivative Balance Sheet Classification (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DerivativesDerivativeBalanceSheetClassificationDetails</Role>
      <ShortName>Derivatives - Derivative Balance Sheet Classification (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2401402 - Disclosure - Fair Value Measurements - Fair Value by Hierarchy (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsFairValueByHierarchyDetails</Role>
      <ShortName>Fair Value Measurements - Fair Value by Hierarchy (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2401403 - Disclosure - Basis of Presentation and Accounting Policies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/BasisOfPresentationAndAccountingPoliciesDetails</Role>
      <ShortName>Basis of Presentation and Accounting Policies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehartford.com/role/BasisOfPresentationAndAccountingPoliciesBusinessCombinationSaleOfHhiTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2401403 - Disclosure - Derivatives - Offsetting Derivative Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DerivativesOffsettingDerivativeAssetsAndLiabilitiesDetails</Role>
      <ShortName>Derivatives - Offsetting Derivative Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2401403 - Disclosure - Fair Value Measurements - Significant Unobservable Inputs - Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsSignificantUnobservableInputsSecuritiesDetails</Role>
      <ShortName>Fair Value Measurements - Significant Unobservable Inputs - Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2401404 - Disclosure - Derivatives - Cash Flow Hedges (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DerivativesCashFlowHedgesDetails</Role>
      <ShortName>Derivatives - Cash Flow Hedges (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2401404 - Disclosure - Fair Value Measurements - Significant Unobservable Inputs Freestanding Derivatives (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsSignificantUnobservableInputsFreestandingDerivativesDetails</Role>
      <ShortName>Fair Value Measurements - Significant Unobservable Inputs Freestanding Derivatives (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2401405 - Disclosure - Derivatives - Fair Value Hedges - Non-qualifying Strategies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DerivativesFairValueHedgesNonQualifyingStrategiesDetails</Role>
      <ShortName>Derivatives - Fair Value Hedges - Non-qualifying Strategies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2401405 - Disclosure - Fair Value Measurements - Fair Value Recurring Basis, Unobservable Input (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsFairValueRecurringBasisUnobservableInputDetails</Role>
      <ShortName>Fair Value Measurements - Fair Value Recurring Basis, Unobservable Input (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2401406 - Disclosure - Derivatives - Credit Risk Assumed through Credit Derivatives (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DerivativesCreditRiskAssumedThroughCreditDerivativesDetails</Role>
      <ShortName>Derivatives - Credit Risk Assumed through Credit Derivatives (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2401406 - Disclosure - Fair Value Measurements - Changes in Unrealized Gains (Losses) Included in Net Income for Financial Instruments  Classified at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsChangesInUnrealizedGainsLossesIncludedInNetIncomeForFinancialInstrumentsClassifiedAtFairValueDetails</Role>
      <ShortName>Fair Value Measurements - Changes in Unrealized Gains (Losses) Included in Net Income for Financial Instruments  Classified at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2401407 - Disclosure - Derivatives - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DerivativesAdditionalInformationDetails</Role>
      <ShortName>Derivatives - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2401407 - Disclosure - Fair Value Measurements - Fair Value Option (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsFairValueOptionDetails</Role>
      <ShortName>Fair Value Measurements - Fair Value Option (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2401408 - Disclosure - Fair Value Measurements - Financial Instruments Not Carried At Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsFinancialInstrumentsNotCarriedAtFairValueDetails</Role>
      <ShortName>Fair Value Measurements - Financial Instruments Not Carried At Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2401409 - Disclosure - Fair Value Measurements - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/FairValueMeasurementsAdditionalInformationDetails</Role>
      <ShortName>Fair Value Measurements - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2403402 - Disclosure - Investments - Net Realized Capital Gains (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsNetRealizedCapitalGainsDetails</Role>
      <ShortName>Investments - Net Realized Capital Gains (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2403403 - Disclosure - Investments - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsAdditionalInformationDetails</Role>
      <ShortName>Investments - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2403404 - Disclosure - Investments - Other Than Temporary Impairment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsOtherThanTemporaryImpairmentDetails</Role>
      <ShortName>Investments - Other Than Temporary Impairment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>2403405 - Disclosure - Investments - Available-for-Sale Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsAvailableForSaleSecuritiesDetails</Role>
      <ShortName>Investments - Available-for-Sale Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>2403406 - Disclosure - Investments - Unrealized Losses on AFS Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsUnrealizedLossesOnAfsSecuritiesDetails</Role>
      <ShortName>Investments - Unrealized Losses on AFS Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>2403407 - Disclosure - Investments - Mortgage Loans- Valuation Allowance Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsMortgageLoansValuationAllowanceActivityDetails</Role>
      <ShortName>Investments - Mortgage Loans- Valuation Allowance Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>2403408 - Disclosure - Investments - Commercial Mortgage Loans Credit Quality (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsCommercialMortgageLoansCreditQualityDetails</Role>
      <ShortName>Investments - Commercial Mortgage Loans Credit Quality (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>2403409 - Disclosure - Investments - Mortgage Loans by Region and Property Type (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsMortgageLoansByRegionAndPropertyTypeDetails</Role>
      <ShortName>Investments - Mortgage Loans by Region and Property Type (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>2403410 - Disclosure - Investments - Securities Lending and Repurchase Agreements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/InvestmentsSecuritiesLendingAndRepurchaseAgreementsDetails</Role>
      <ShortName>Investments - Securities Lending and Repurchase Agreements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>2409402 - Disclosure - Reinsurance Level 4 Reinsurance Recoverables (details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ReinsuranceLevel4ReinsuranceRecoverablesDetails</Role>
      <ShortName>Reinsurance Level 4 Reinsurance Recoverables (details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>2409403 - Disclosure - Reinsurance Level 4 Reinsurance Revenues (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ReinsuranceLevel4ReinsuranceRevenuesDetails</Role>
      <ShortName>Reinsurance Level 4 Reinsurance Revenues (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>2411402 - Disclosure - Deferred Policy Acquisition Costs and Value of Business Acquired Level 4 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/DeferredPolicyAcquisitionCostsAndValueOfBusinessAcquiredLevel4Details</Role>
      <ShortName>Deferred Policy Acquisition Costs and Value of Business Acquired Level 4 (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>2414402 - Disclosure - Reserve for Future Policy Benefits and SA Liabilities Level 4 Changes in Reserve for Future Policy Benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ReserveForFuturePolicyBenefitsAndSaLiabilitiesLevel4ChangesInReserveForFuturePolicyBenefitsDetails</Role>
      <ShortName>Reserve for Future Policy Benefits and SA Liabilities Level 4 Changes in Reserve for Future Policy Benefits (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>2414403 - Disclosure - Reserve for Future Policy Benefits and SA Liabilities Level 4 Account Value by Type (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ReserveForFuturePolicyBenefitsAndSaLiabilitiesLevel4AccountValueByTypeDetails</Role>
      <ShortName>Reserve for Future Policy Benefits and SA Liabilities Level 4 Account Value by Type (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>2414404 - Disclosure - Reserve for Future Policy Benefits and SA Liabilities Level 4 Separate Accounts by Major Category of Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ReserveForFuturePolicyBenefitsAndSaLiabilitiesLevel4SeparateAccountsByMajorCategoryOfInvestmentsDetails</Role>
      <ShortName>Reserve for Future Policy Benefits and SA Liabilities Level 4 Separate Accounts by Major Category of Investments (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>2415402 - Disclosure - Income Taxes Income Taxes - Effective Income Tax Rate Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/IncomeTaxesIncomeTaxesEffectiveIncomeTaxRateReconciliationDetails</Role>
      <ShortName>Income Taxes Income Taxes - Effective Income Tax Rate Reconciliation (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>2415403 - Disclosure - Income Taxes Income Taxes - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/IncomeTaxesIncomeTaxesAdditionalInformationDetails</Role>
      <ShortName>Income Taxes Income Taxes - Additional Information (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>2415404 - Disclosure - Income Taxes Income Taxes - Net Operating Loss Carrryover (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/IncomeTaxesIncomeTaxesNetOperatingLossCarrryoverDetails</Role>
      <ShortName>Income Taxes Income Taxes - Net Operating Loss Carrryover (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>2415405 - Disclosure - Income Taxes Income Taxes - AMT Credit and Foreign Tax Credit Carryover (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/IncomeTaxesIncomeTaxesAmtCreditAndForeignTaxCreditCarryoverDetails</Role>
      <ShortName>Income Taxes Income Taxes - AMT Credit and Foreign Tax Credit Carryover (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>2416401 - Disclosure - Commitments and Contingencies Commitments and Contingencies - Derivative and Commitments(Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/CommitmentsAndContingenciesCommitmentsAndContingenciesDerivativeAndCommitmentsdetails</Role>
      <ShortName>Commitments and Contingencies Commitments and Contingencies - Derivative and Commitments(Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>2417401 - Disclosure - Transactions with Affiliates Level 4 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/TransactionsWithAffiliatesLevel4Details</Role>
      <ShortName>Transactions with Affiliates Level 4 (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>2417402 - Disclosure - Transactions with Affiliates Level 4 Reinsurance Disclosures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/TransactionsWithAffiliatesLevel4ReinsuranceDisclosuresDetails</Role>
      <ShortName>Transactions with Affiliates Level 4 Reinsurance Disclosures (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>2418402 - Disclosure - Changes in and Reclassifications from Accumulated Other Comprehensive Income AOCI Rollforward</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ChangesInAndReclassificationsFromAccumulatedOtherComprehensiveIncomeAociRollforward</Role>
      <ShortName>Changes in and Reclassifications from Accumulated Other Comprehensive Income AOCI Rollforward</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>2418403 - Disclosure - Changes in and Reclassifications from Accumulated Other Comprehensive Income Reclassifications from AOCI (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/ChangesInAndReclassificationsFromAccumulatedOtherComprehensiveIncomeReclassificationsFromAociDetails</Role>
      <ShortName>Changes in and Reclassifications from Accumulated Other Comprehensive Income Reclassifications from AOCI (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>2419402 - Disclosure - Other Intangible Assets Level 4 - Other Intangible Assets Gross/Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/OtherIntangibleAssetsLevel4OtherIntangibleAssetsGrossNet</Role>
      <ShortName>Other Intangible Assets Level 4 - Other Intangible Assets Gross/Net</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>2419403 - Disclosure - Other Intangible Assets Level 4 - Expected Pre-tax Amortization Expense</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehartford.com/role/OtherIntangibleAssetsLevel4ExpectedPreTaxAmortizationExpense</Role>
      <ShortName>Other Intangible Assets Level 4 - Expected Pre-tax Amortization Expense</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="hig-20180630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9999.htm</HtmlFileName>
      <LongName>Uncategorized Items - hig-20180630.xml</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/role/uncategorizedFacts</Role>
      <ShortName>Uncategorized Items - hig-20180630.xml</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>hig-20180630.xml</File>
    <File>hig-20180630.xsd</File>
    <File>hig-20180630_cal.xml</File>
    <File>hig-20180630_def.xml</File>
    <File>hig-20180630_lab.xml</File>
    <File>hig-20180630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://xbrl.sec.gov/invest/2013-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2014-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/us-gaap/2017-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
