THG


Line plots across dimensions of each concept
Line plots across concepts
Tables

Table of contents



us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:IncomeLossFromContinuingOperationsPerBasicShare

us-gaap:IncomeLossFromContinuingOperationsPerDilutedShare

us-gaap:AllocatedShareBasedCompensationExpense

us-gaap:BenefitsLossesAndExpenses

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:DeferredPolicyAcquisitionCostAmortizationExpense

us-gaap:GainLossOnInvestments

us-gaap:IncomeLossFromContinuingOperations
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:IncomeTaxExpenseBenefit
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:InterestExpenseDebt

us-gaap:NetIncomeLoss
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:NetInvestmentIncome
us-gaap:StatementBusinessSegments

us-gaap:OperatingIncomeLoss
us-gaap:StatementBusinessSegments

us-gaap:OtherComprehensiveIncomeLossNetOfTax

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:PremiumsEarnedNet

us-gaap:ProfitLoss

us-gaap:RealizedInvestmentGainsLosses
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:Revenues

us-gaap:Assets
us-gaap:ConsolidatedEntities
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:Liabilities
us-gaap:ConsolidatedEntities

us-gaap:LiabilitiesAndStockholdersEquity
us-gaap:ConsolidatedEntities

us-gaap:StockholdersEquity
us-gaap:ConsolidatedEntities
us-gaap:CumulativeEffectPeriodOfAdoption, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:CashAndCashEquivalentsAtCarryingValue
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures

us-gaap:Goodwill

us-gaap:EquitySecuritiesFvNi
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:ValuationTechnique
us-gaap:FairValueByMeasurementFrequency

us-gaap:OtherAssets
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:AccruedIncomeTaxesCurrent

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:StockholdersEquity
us-gaap:ConsolidatedEntities
us-gaap:CumulativeEffectPeriodOfAdoption, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapitalCommonStock
us-gaap:ConsolidatedEntities

us-gaap:RetainedEarningsAccumulatedDeficit
us-gaap:ConsolidatedEntities

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
us-gaap:ConsolidatedEntities

us-gaap:TreasuryStockValue
us-gaap:ConsolidatedEntities
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:ProfitLoss

us-gaap:ShareBasedCompensation

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:PaymentsOfDividends

us-gaap:PaymentsForRepurchaseOfCommonStock

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxAssetsNet

us-gaap:UnrecognizedTaxBenefits
us-gaap:ShareRepurchaseProgram
thg:AcceleratedShareRepurchasesFinalSettlementOfSharesReceived
us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType
us-gaap:ShareRepurchaseProgram
thg:AcceleratedShareRepurchasesInitialDeliveryOfSharesReceived

thg:AmortizationOfDefinedBenefitPlanCosts
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:MeasurementInputType, us-gaap:ValuationTechnique
thg:DebtSecuritiesAvailableForSaleMeasurementInput1
us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:MeasurementInputType, us-gaap:ValuationTechnique

thg:FeesCommissionsAndOtherIncome

thg:GainLossOnInvestmentsFromContinuingOperations

thg:ImpairmentsOnFixedMaturitiesCreditRelatedLosses

thg:ImpairmentsOnFixedMaturitiesIncludedInIntendToSell

thg:IncomeLossFromContinuingOperationsExcludingNonoperatingItemsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

thg:OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementTax

thg:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAociPensionAndOtherPostretirementBenefitPlansForNetActuarialGainLoss
us-gaap:StatementEquityComponents
thg:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAociPensionAndOtherPostretirementBenefitPlansForNetActuarialGainLossAndNetPriorServiceCostCreditNetOfTax

thg:OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostBeforeTax

thg:OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostNetOfTax

thg:OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostTax

thg:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesHavingCreditLossesRecognizedInTheConsolidatedStatementsOfIncome

thg:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesHavingNoCreditLossesRecognizedInTheConsolidatedStatementsOfIncome

thg:OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementTax

thg:OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementTax
us-gaap:StatementEquityComponents
thg:OtherComprehensiveIncomeLossPercentageOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncomeForPensionAndPostRetirementBenefitsAllocatedToLossAdjustmentExpenses
us-gaap:StatementEquityComponents
thg:OtherComprehensiveIncomeLossPercentageOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncomeForPensionAndPostRetirementBenefitsAllocatedToOtherOperatingExpenses
us-gaap:StatutoryAccountingPracticesByJurisdiction
thg:PaymentsOfExtraordinaryDividends

thg:PaymentsToAcquireEquitySecuritiesAndOtherInvestments

thg:PerShareEffectOfDilutiveSecuritiesOnIncomeFromContinuingOperations

thg:PerShareEffectOfDilutiveSecuritiesOnNetIncome

thg:ProceedsFromSaleOfEquitySecuritiesAndOtherInvestments
us-gaap:ShareRepurchaseProgram
thg:ShareRepurchaseProgramPercentageOfSharesRepurchased
us-gaap:StatementEquityComponents
us-gaap:AcceleratedShareRepurchaseProgramAdjustment

us-gaap:AllocatedShareBasedCompensationExpenseNetOfTax

us-gaap:CurrentIncomeTaxExpenseBenefit
us-gaap:InvestmentType
us-gaap:DebtSecuritiesAvailableForSaleRealizedGain
us-gaap:InvestmentType
us-gaap:DebtSecuritiesAvailableForSaleRealizedLoss

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets

us-gaap:DefinedBenefitPlanInterestCost

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost

us-gaap:DepreciationAndAmortization
us-gaap:StatementEquityComponents
us-gaap:DividendsCash

us-gaap:EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense

us-gaap:EquitySecuritiesFvNiGainLoss

us-gaap:EquitySecuritiesFvNiRealizedGainLoss

us-gaap:EquitySecuritiesFvNiUnrealizedGainLoss

us-gaap:FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss
us-gaap:InvestmentType

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
us-gaap:FairValueByAssetClass

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss
us-gaap:InvestmentType

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
us-gaap:InvestmentType

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
us-gaap:InvestmentType

us-gaap:FederalIncomeTaxExpenseBenefitContinuingOperations

us-gaap:GainLossOnRepurchaseOfDebtInstrument

us-gaap:ImpairmentOfInvestments
us-gaap:InvestmentType
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTax
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes

us-gaap:IncreaseDecreaseInDeferredPolicyAcquisitionCosts

us-gaap:IncreaseDecreaseInInsuranceLiabilities

us-gaap:IncreaseDecreaseInPremiumsReceivable

us-gaap:IncreaseDecreaseInReinsuranceRecoverable
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities
us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:InsuranceServicesRevenue
us-gaap:StatementBusinessSegments

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax

us-gaap:OtherComprehensiveIncomeLossBeforeTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax

us-gaap:OtherComprehensiveIncomeLossTax

us-gaap:OtherCostAndExpenseOperating
us-gaap:StatementBusinessSegments
us-gaap:OtherOperatingIncomeExpenseNet
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:OtherThanTemporaryImpairmentLossDebtSecuritiesAvailableForSaleRecognizedInEarnings

us-gaap:PaymentsForLossesAndLossAdjustmentExpense

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities
us-gaap:InvestmentType
us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt

us-gaap:ProceedsFromStockOptionsExercised
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense
us-gaap:StatementEquityComponents
us-gaap:TreasuryStockValueAcquiredCostMethod
us-gaap:StatementBusinessSegments
us-gaap:UnderwritingIncomeLoss

thg:AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses
us-gaap:InvestmentType

thg:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCostNetOfAllowanceForCreditLosses
us-gaap:InvestmentType
thg:AvailableForSaleSecuritiesDebtMaturitiesYearFiveAmortizedCostBasis
us-gaap:InvestmentType
thg:AvailableForSaleSecuritiesDebtMaturitiesYearFourAmortizedCostBasis
us-gaap:InvestmentType
thg:AvailableForSaleSecuritiesDebtMaturitiesYearThreeAmortizedCostBasis
us-gaap:InvestmentType
thg:AvailableForSaleSecuritiesDebtMaturitiesYearTwoAmortizedCostBasis

thg:AvailableForSaleSecuritiesDebtSecuritiesIncludingHeldForSaleFairValue

thg:DebtLongTermAndShortTermCombinedAmountGross

thg:DefinedBenefitPlanPensionPlansWithPlanAssetsInExcessOfAccumulatedBenefitObligations
us-gaap:StatutoryAccountingPracticesByJurisdiction
thg:ExtraordinaryDividendsPayableCurrentAndNoncurrent
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis
thg:FinancialInstrumentThatWereNotCarriedAtFairValuesIncludingHeldForSale
us-gaap:FairValueByMeasurementBasis

thg:PercentageOfInvestmentsNotIncludedInFairValueOfFinancialInstruments
us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType
thg:PercentageOfNumberOfSharesExpectedToBeReceivedUnderAgreement
us-gaap:StatementEquityComponents
thg:RealizedGainsInAccumulatedOtherComprehensiveIncomeToBeReleasedIntoIncomeFromContinuingOperationsInFuture
us-gaap:StatementGeographical
thg:ShortdurationInsuranceContractsPercentageOfGrossIncurredClaims
us-gaap:InvestmentType
thg:ValuationAllowanceOfOtherInvestments
us-gaap:ShareRepurchaseProgram
us-gaap:AcceleratedShareRepurchasesSettlementPaymentOrReceipt
us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
us-gaap:ConsolidatedEntities
us-gaap:AccountsPayableAndOtherAccruedLiabilities

us-gaap:AccruedInvestmentIncomeReceivable
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:AlternativeInvestment
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType
us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:AlternativeInvestmentMeasurementInput
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:ValuationTechnique
us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:ValuationTechnique
us-gaap:FairValueByMeasurementBasis
us-gaap:AssetsFairValueDisclosure

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperation
us-gaap:DisposalGroupClassification
us-gaap:ProductOrService
us-gaap:InvestmentType
us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
us-gaap:InvestmentType
us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis
us-gaap:ConsolidatedEntities
us-gaap:InvestmentType

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue

us-gaap:AvailableForSaleSecuritiesDebtSecurities
us-gaap:FinancialInstrument
us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis
us-gaap:CashAndCashEquivalentsFairValueDisclosure
us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument, us-gaap:ValuationTechnique

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations
us-gaap:ConsolidatedEntities
us-gaap:DebtInstrument
us-gaap:DebtInstrumentCarryingAmount

us-gaap:DebtInstrumentUnamortizedDiscount
us-gaap:DebtInstrument

us-gaap:DebtLongtermAndShorttermCombinedAmount
us-gaap:ConsolidatedEntities
us-gaap:InvestmentType
us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLoss

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
us-gaap:InvestmentSecondaryCategorization
us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
us-gaap:InvestmentSecondaryCategorization
us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
us-gaap:InvestmentSecondaryCategorization
us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPosition
us-gaap:InvestmentSecondaryCategorization
us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
us-gaap:InvestmentSecondaryCategorization
us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredPolicyAcquisitionCosts

us-gaap:DeferredTaxAssetsOther

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost

us-gaap:DeferredTaxLiabilitiesInvestments

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanBenefitObligation
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear
us-gaap:DefinedBenefitPlanByPlanAssetCategories
us-gaap:DefinedBenefitPlanFairValueOfPlanAssets
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByMeasurementBasis
us-gaap:RetirementPlanTaxStatus
us-gaap:RetirementPlanTaxStatus
us-gaap:DefinedBenefitPlanFundedStatusOfPlan
us-gaap:DefinedBenefitPlanByPlanAssetCategories
us-gaap:DefinedBenefitPlanWeightedAverageAssetAllocations
us-gaap:StatutoryAccountingPracticesByJurisdiction
us-gaap:DividendsPayableCurrentAndNoncurrent
us-gaap:AwardType
us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:ValuationTechnique
us-gaap:EquitySecuritiesFvNiMeasurementInput
us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:ValuationTechnique

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue

us-gaap:FederalHomeLoanBankStock
us-gaap:ConsolidatedEntities
us-gaap:InterestPayableCurrentAndNoncurrent
us-gaap:InvestmentType, us-gaap:StatementEquityComponents
us-gaap:InvestmentOwnedUnrecognizedUnrealizedAppreciationDepreciationNet
us-gaap:StatementEquityComponents

us-gaap:Investments
us-gaap:BalanceSheetLocation, us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument, us-gaap:ValuationTechnique
us-gaap:InvestmentsFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument, us-gaap:InvestmentType, us-gaap:ValuationTechnique
us-gaap:FairValueByMeasurementFrequency

us-gaap:LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation
us-gaap:ProductOrService

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense
us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent
us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments, us-gaap:Subsegments

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet
us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments, us-gaap:Subsegments
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis
us-gaap:LongTermDebtFairValue
us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument, us-gaap:ValuationTechnique

us-gaap:OtherInvestments
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency
us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType
us-gaap:InvestmentType
us-gaap:StatementGeographical, us-gaap:InvestmentType

us-gaap:PremiumsAndOtherReceivablesNet

us-gaap:PrepaidReinsurancePremiums

us-gaap:ReinsurancePayable

us-gaap:ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments
us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments, us-gaap:Subsegments

us-gaap:ReinsuranceRecoverables
us-gaap:ProductOrService
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionDueFromToRelatedParty
us-gaap:FairValueByLiabilityClass
us-gaap:SecuritiesHeldAsCollateralAtFairValue
us-gaap:FederalHomeLoanBankAdvancesBranchOfFHLBBank
us-gaap:InvestmentType
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
us-gaap:AwardType
us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1

us-gaap:SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

us-gaap:SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet
us-gaap:ShortdurationInsuranceContractsAccidentYear, us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented
us-gaap:Subsegments
us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense
us-gaap:StatementScenario, us-gaap:StatutoryAccountingPracticesByJurisdiction
us-gaap:StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPayments

us-gaap:StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance

us-gaap:StatutoryAccountingPracticesStatutoryCapitalAndSurplusRequired
us-gaap:ShareRepurchaseProgram
us-gaap:StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount
us-gaap:InvestmentType

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost
us-gaap:InvestmentType

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue
us-gaap:InvestmentType
us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersByAffiliationWithRegistrant
us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersDeferredPolicyAcquisitionCosts
us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersByAffiliationWithRegistrant
us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersReservesForUnpaidClaimsAndClaimsAdjustmentExpense
us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersByAffiliationWithRegistrant
us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersUnearnedPremiums

us-gaap:SupplementaryInsuranceInformationDeferredPolicyAcquisitionCosts
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:SupplementaryInsuranceInformationLiabilityForFuturePolicyBenefitsLossesClaimsAndLossExpenseReserves
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:SupplementaryInsuranceInformationOtherPolicyClaimsAndBenefitsPayable
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:SupplementaryInsuranceInformationUnearnedPremiums
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ConsolidatedEntities
us-gaap:TreasuryStockShares

us-gaap:UnearnedPremiums

us-gaap:UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued

us-gaap:ValuationAllowancesAndReservesBalance
us-gaap:ValuationAllowancesAndReservesType

Plots across concepts


IncomeStatement
Other Comprehensive Income Loss Net Of Tax
Expenses
Other Nonoperating Income Expense
Balance Sheet
Cash And Cash Equivalents At Carrying Value
Assets
Cash And Cash Equivalents At Carrying Value
Current Assets
Cash And Cash Equivalents At Carrying Value
NonCurrent Assets
Goodwill
Liabilities
Accounts Payable And Accrued Liabilities Current And Noncurrent
Stockholders Equity
Common Stock Value
CashFlow
Net Cash Provided By Used In Financing Activities
NetCashProvidedByUsedInOperatingActivities
Share Based Compensation
NetCashProvidedByUsedInInvestingActivities
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInFinancingActivities
Net Cash Provided By Used In Financing Activities
Shares
Weighted Average Number Of Shares Outstanding Basic

Tables

  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding ▁█36.536.9NA38.038.338.3NA40.241.241.2NA43.143.143.1NA42.942.842.9NA43.043.443.5NA44.945.045.1NA44.944.944.8NA44.644.845.3NA45.245.445.5NA45.34.54e-0546.0NA45.74.55e-0548.2
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic ▁█35.936.4NA37.738.038.3NA39.640.740.6NA42.542.542.5NA42.442.542.5NA42.743.042.9NA44.044.244.2NA44.144.143.9NA43.844.044.6NA44.644.944.9NA45.34.54e-0545.3NA44.94.49e-0547.5
 us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities us-gaap:StockCompensationPlanNA0.2NA0.80.90.4NA0.2NA0.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:EarningsPerShareBasic ▇▆█▆▆▁▆▆▅▆▆▅▅▄▄▃▅▄▂▅▃▅▅▅▆▄▅▄▅▄▄▄▄▄▁▄▃▄▄▂▂▃▄▄▃▄3.582.554.493.153.03-1.042.83.01.823.012.922.362.341.591.210.261.851.06-0.322.070.051.821.791.782.731.242.041.251.881.241.61.41.211.49-1.240.910.461.111.1-0.21-0.70.651.291.160.050.88
us-gaap:EarningsPerShareDiluted ▇▆█▆▆▁▆▆▅▆▆▅▅▄▄▃▅▄▂▅▃▅▅▅▆▄▅▄▅▄▄▄▄▄▁▄▃▄▄▂▂▃▄▄▃▄3.522.514.433.133.01-1.042.762.961.792.972.882.332.311.571.20.261.831.05-0.322.060.051.81.761.742.681.222.01.221.841.221.571.371.191.46-1.240.890.461.091.09-0.21-0.70.641.271.150.050.87
us-gaap:IncomeLossFromContinuingOperationsPerBasicShare ▇▆█▆▆▁▆▆▅▆▃▅▅▄▄▃▅▄▂▅▃▅▅▅▆▄▅▄▅▄▄▄▄▄▁▄▃▄▄▂▂▃▄▄▃▄3.6000000000000003e-062.5499999999999997e-064.52e-063.1699999999999997e-063.03e-06-1.01e-062.81e-062.81e-062.09e-063.02e-065.0000000000000004e-082.4500000000000003e-062.33e-061.59e-061.5800000000000001e-062.9e-071.85e-061.06e-06-2.9e-072.0699999999999997e-064e-081.8200000000000002e-061.8000000000000001e-061.75e-062.74e-061.24e-062.05e-061.25e-061.87e-061.25e-061.48e-061.4e-061.21e-061.49e-06-1.24e-069.200000000000001e-072.2e-071.13e-061.03e-06-2.1e-07-7.1e-076.2e-071.2700000000000001e-061.1399999999999999e-065.0000000000000004e-088.900000000000001e-07
us-gaap:IncomeLossFromContinuingOperationsPerDilutedShare ▇▆█▆▆▁▆▆▅▆▃▅▅▄▄▃▅▄▂▅▃▅▅▅▆▄▅▄▅▄▄▄▄▄▁▄▃▄▄▂▂▃▄▄▃▄3.55e-062.52e-064.4699999999999996e-063.14e-063.01e-06-1.01e-062.77e-062.77e-062.06e-062.98e-065.0000000000000004e-082.4100000000000002e-062.3e-061.57e-061.56e-062.8e-071.83e-061.0500000000000001e-06-2.9e-072.06e-064e-081.79e-061.76e-061.72e-062.69e-061.22e-062.01e-061.22e-061.8400000000000002e-061.22e-061.4499999999999999e-061.37e-061.19e-061.47e-06-1.24e-069.000000000000001e-072.2e-071.1100000000000002e-061.02e-06-2.1e-07-7.1e-076.1e-071.25e-061.12e-065.0000000000000004e-088.8e-07
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:AllocatedShareBasedCompensationExpense ███▇▆▇▇▆▆▆▆▆▆▄▁▆▆▄▅▄▄▄▄▃▆▅▆▅▅▅▅▄▃▅▄▅▃▆▄▅▄▅▃▄▄5.45.65.74.94.55.04.74.14.44.24.34.04.63.00.84.24.13.23.53.02.72.82.91.94.23.34.03.83.83.53.53.22.13.63.03.52.24.12.73.52.63.42.53.12.7NA
us-gaap:BenefitsLossesAndExpenses ▆▆▅▆▅▆▆▅▅▅▆▅▇▇▇█▆▇█▆▇▆▆▆▆▇▆▇▆▆▆▆▆▅█▆▆▅▅▆▄▂▂▁▂▁1133.51169.21090.01101.21081.21110.11124.51084.41088.81070.91101.71043.91242.91250.31209.61316.31155.11201.91287.81117.11229.11119.51105.31123.11144.51221.71162.21190.31165.31171.81140.81115.71116.71091.41290.41104.51116.11051.01072.71126.7913.6796.3757.7730.9765.2687.3
us-gaap:ComprehensiveIncomeNetOfTax ▆▂▆▅█▂▅▅▆▆▆▄▄▁▄▄▅▄▁▄▄▆▄▄▄▄▄▃▅▅▄▄▂▄▂▅▄▅▄▃▃▄▃▅▄▄191.3-92.1184.7147.8368.1-122.0108.9164.2178.4241.2197.978.750.6-160.345.118.296.171.6-177.786.080.0175.727.542.333.875.482.21.9121.6105.159.959.4-80.063.5-93.2101.358.8104.468.2-0.75.737.6-8.1129.360.780.8
us-gaap:DeferredPolicyAcquisitionCostAmortizationExpense ▆▅▅▅▅▅▅▅▅▅▅▅███▇▇▇▇▆▆▆▆▆▇▇▇▆▆▆▆▆▅▆▆▅▅▅▆▆▂▂▂▂▁▁244.2240.3239.1237.7237.3236.9233.9232.8230.5229.5227.1224.4288.9288.0280.5275.1264.6266.4263.8257.9254.4259.1251.6259.0262.0260.6266.7260.0259.6253.7251.9243.9232.7242.5241.1235.8233.1228.1250.8241.1181.3180.8178.2173.4163.0154.4
us-gaap:GainLossOnInvestments ▇▇█▇█▁▇▆▆▇▄▇▆▅▆▆▆▆▆▆▆▆▆▆▆▆▇▆▇▆▆▆▆▆▇▆▆▆▆▆▆▆▆▆▆▆30.838.364.738.464.3-162.434.514.611.948.4-54.523.24.0-23.42.513.45.91.93.64.2-0.71.5-10.58.012.69.418.64.922.24.410.71.013.78.118.95.0-3.43.13.28.213.43.312.95.70.210.9
us-gaap:IncomeLossFromContinuingOperations ▇▆█▇▆▂▆▆▅▇▃▆▆▅▅▃▅▄▂▆▃▅▅▅▇▄▆▄▅▄▅▅▄▅▁▄▃▄▄▂▂▄▅▄▃▄129.692.8165.9119.5115.3-38.7110.2111.285.0122.62.1104.099.267.867.112.378.445.2-12.288.31.978.177.877.2120.954.990.155.082.554.764.961.353.166.4-55.340.99.850.746.1-9.7-32.427.957.451.42.242.2
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest ▇▆█▇▇▂▆▆▆▇▄▆▆▅▆▄▆▅▃▆▃▆▆▆▇▅▆▅▅▅▅▆▅▅▁▅▄▅▅▃▂▄▅▅▄159.9114.1207.0148.6143.1-53.9133.4130.3109.8148.61.1122.7119.980.6122.68.9111.059.0-32.8124.1-7.1108.199.4110.4152.684.3116.370.185.968.786.390.663.787.5-119.748.315.169.560.7-25.0-57.639.464.767.42.9NA
us-gaap:IncomeTaxExpenseBenefit ▆▆▇▆▆▃▆▆▆▆▄▆▆▅█▄▆▅▃▇▄▆▆▇▆▆▇▆▆▅▆▆▅▆▁▅▄▆▅▄▃▅▆▆▄▅30.321.341.129.127.8-15.223.219.124.826.0-1.018.720.712.855.5-3.432.613.8-20.635.8-9.030.021.633.231.722.132.820.325.217.423.324.812.822.5-51.112.31.320.117.1-9.0-27.39.618.221.70.917.1
us-gaap:InterestExpenseDebt ▁▁▁▂▂▂▂▂▂▂▃▃▃▄▄▄▄▄▄▄▇▆▆▆▆▇▇▇▇▇▇▇█▆▆▆▇▇▇█▃▂▃▄▄▂8.58.58.59.89.49.49.49.49.39.411.211.211.612.412.212.112.212.012.112.515.614.714.614.714.915.916.316.316.316.316.616.617.414.715.214.615.916.216.417.410.810.411.511.811.79.3
us-gaap:NetIncomeLoss ▇▆█▇▆▁▆▇▅▇▇▆▆▅▄▃▅▄▂▆▃▅▅▅▇▅▆▅▅▄▅▅▄▅▁▄▃▄▄▂▂▄▅▄▃▄128.592.7164.6118.9115.2-40.0109.8118.974.0122.4123.6100.499.367.751.511.178.445.2-13.588.42.078.277.678.3120.754.989.954.982.654.670.161.353.466.2-55.040.420.849.749.3-9.7-31.829.358.452.32.341.8
us-gaap:NetInvestmentIncome ▆▆▄▄▁▄▅▄▄▄▄▃▇█▇▆▅▅▆▄▄▄▄▄▅▄▄▄▄▄▄▃▄▄▄▄▄▄▄▄▂▂▂▂▂▂75.676.870.2000000000000367.657.769.672.768.869.670.269.466.478.782.978.176.672.371.174.267.869.168.370.068.370.770.168.867.567.067.068.165.767.967.370.169.268.568.869.067.861.060.463.061.361.861.1
us-gaap:OperatingIncomeLoss █▆█▇▆▇▇▇▇▇▆▇▇▇█▄▇▆▃▇▆▇▇▇▇▇█▆▇▆▇▇▆▇▁▆▅▆▆▄▃▅137.385.1150.3128.488.9117.1110.5126.3107.0109.893.1112.8129.8116.6135.213.1118.969.1-22.1129.894.7120.4124.0122.5119.4100.2132.686.4102.285.0102.9107.281.1102.2-104.562.931.085.777.5-8.2-47.349.8NANANANA
us-gaap:OtherComprehensiveIncomeLossNetOfTax ▅▂▅▅█▃▄▅▆▆▅▄▄▁▄▄▅▅▂▄▅▆▄▄▃▅▄▄▅▅▄▄▂▄▄▅▅▅▅▄▅62.8-184.820.128.9252.9-82.0-0.945.3104.4118.874.3-21.7-48.7-228.0-6.47.117.726.4-164.2-2.478.097.5-50.1-36.0-86.920.5-7.7-53.039.050.5-10.2-1.9-133.4-2.7-38.260.938.054.718.99.037.5NANANANANA
us-gaap:OtherNonoperatingIncomeExpense NANA0.0-1.6-0.1NA-2.0-1.4NANANA-1.9-2.0NA-2.9-5.5-1.6NA0.22.50.2NA0.30.2-0.4NA0.10.4-0.4NANANANANANANANANANANANANANANANANA
us-gaap:PolicyholderBenefitsAndClaimsIncurredNet ▆▆▅▅▅▆▆▅▅▅▅▅▇▇▆█▆▆▇▅▆▅▅▅▆▆▅▆▆▆▅▅▅▅█▅▆▅▅▆▄▂▂▁▂▁745.1781.3695.3709.7712.0728.2742.9705.3717.7699.6706.1676.4783.6785.8759.2878.0725.0766.5843.4692.0729.7699.6675.4690.7744.9773.1695.9755.6725.5750.5689.7695.9692.1683.4872.5708.4732.1661.4687.4734.9617.5511.0471.7454.6498.4431.6
us-gaap:PremiumsEarnedNet ▇▇▇▆▆▆▇▆▆▆▆▆███▇▇▇▇▇▇▇▆▇▇▇▇▇▇▇▆▆▆▆▆▆▅▅▅▅▂▂▂▂▁▁1179.81161.81154.01135.41096.61141.41144.31124.11111.01095.11082.01071.71272.91263.61244.01226.91181.21181.31170.41160.91145.51151.31137.91150.11205.81211.01188.61184.01174.71163.01140.71124.71090.81094.31082.51071.01050.01035.61047.81018.6770.5761.7748.7728.0697.8666.5
us-gaap:ProfitLoss ▇▆█▆▆▁▆▆▅▇▇▆▆▅▄128.592.7164.6118.9115.2-40.0109.8118.974.0122.4123.6100.499.367.751.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RealizedInvestmentGainsLosses ▃▁▃▄▂▃▃▂▂▂▁▂▂▂▃▆▄▃▃▃▃█▄▅▆▅█▃█▃▅▃▆▄▇▄▁▃▂▄▅▃▇▄▃▅4.8-1.65.88.20.83.13.90.60.8-0.4-2.6-0.2-0.40.33.914.77.73.35.54.34.322.47.512.214.512.123.75.222.34.413.03.114.88.621.07.2-1.85.0-0.59.714.24.719.37.13.613.6
us-gaap:Revenues ▇▇▇▇▆▅▇▆▆▆▅▆████▇▇▇▇▆▆▆▇▇▇▇▇▇▇▆▆▆▆▆▆▅▅▅▅▂▂▂▂▁▁1293.41283.31297.01249.81224.31056.21257.91214.71198.61219.51102.81166.61362.81330.91332.21325.21266.11260.91255.01241.21222.01227.61204.71233.51297.11298.71285.11265.61273.01243.91229.01201.81182.61180.31184.01157.71127.21121.81135.91108.0853.9833.8833.3804.0768.3746.6
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:Assets ▆▆▆▆▅▅▅▅▅▄▅█████▇▇▇▇▇▆▆▆▇▆▆▆▆▆▆▆▆▆▆▆▆▅▅▅▁▁▁13728.113448.013443.713393.812838.612277.412490.512627.212159.911983.412399.715624.315403.615334.215469.615389.314792.714490.814220.414363.714163.614027.713790.914041.014144.713925.613759.713960.213964.813643.013378.713463.313306.413442.113484.913330.113118.712913.412624.412684.58981.38514.98569.9NANANA
us-gaap:Liabilities ▆▆▅▅▅▅▅▅▄▄▅█████▇▇▇▇▆▆▆▆▇▆▆▆▆▆▆▆▆▆▆▆▆▆▅▅▁▁▁10574.110401.210241.510238.89766.99540.89574.39540.49218.89056.49445.012641.912463.812421.112471.912417.311820.211577.311362.911318.011153.911070.710946.511163.511236.211025.710915.711188.311169.710961.910784.210919.110810.710818.110889.510630.710501.210334.410114.610229.66496.36026.26109.4NANANA
us-gaap:LiabilitiesAndStockholdersEquity ▆▆▆▆▅▅▅▅▅▄▅█████▇▇▇▇▇▆▆▆▇▆▆▆▆▆▆▆▆▆▆▆▆▅▅▅▁▁▁13728.113448.013443.713393.812838.612277.412490.512627.212159.911983.412399.715624.315403.615334.215469.615389.314792.714490.814220.414363.714163.614027.713790.914041.014144.713925.613759.713960.213964.813643.013378.713463.313306.413442.113484.913330.113118.712913.412624.412684.58981.38514.98569.9NANANA
us-gaap:StockholdersEquity █▇██▇▄▆▇▆▆▆▆▆▆▆▆▆▆▅▇▇▆▅▅▆▆▅▅▅▄▃▃▃▄▃▄▃▃▃▂▂▂▂▂▁▁3154.03046.83202.23155.03071.72736.62916.23086.82941.12927.02954.72982.42939.82913.12997.72972.02972.52913.52857.53045.73009.72957.02844.42877.52908.52899.92844.02771.92795.12681.12594.52544.22495.72624.02595.42699.42617.52579.02509.82454.92485.02488.72460.52478.82351.62302.2
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:CashAndCashEquivalentsAtCarryingValue ▁▁▁▂▂▁▂▁▂▁█▁▂▂▃▂▃▂▂▃▃▃▃▃▅▃▃▄▅▄▄▅▅▅▅▄▄▅▆▇▆▂▂▂▂▂106.4112.1120.6231.5182.6143.9215.7157.6179.8168.51020.7117.9244.9258.0376.4227.2317.8257.0282.6315.9361.6406.7338.8385.1583.7403.9373.3509.6606.2476.3486.2602.2690.4691.0564.8462.0520.8628.3820.4922.7721.6218.8290.4271.6260.9209.2
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures us-gaap:ConsolidatedEntities srt:ParentCompanyNANA3718.3NANANA3352.2NANANA2800.1NANANA3455.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:Goodwill ▁▁▁▁▁▁▁▁▁▁▁▁▅▅▅▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃█▁▁▁178.8178.8178.8178.8178.8178.8178.8178.8178.8178.8178.8178.8192.1192.6192.6185.3185.2184.9184.8185.1185.2185.7186.0184.0184.2184.3184.6184.8185.2185.0184.9184.8184.4184.4184.9184.8184.6184.4185.5200.6178.8178.8179.2NANANA
us-gaap:EquitySecuritiesFvNi ▇█▆▃▁▁▆▅▄▃▂▆618.6641.0598.5490.5458.9447.0575.7570.8531.3504.7464.4574.8NANA576.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 us-gaap:AccruedIncomeTaxesCurrent us-gaap:ConsolidatedEntities srt:ParentCompanyNANA2.7NANANA3.5NANANA46.9NANANA3.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:DeferredIncomeTaxLiabilitiesNet ▅▁█▅▃83.264.097.384.674.9NA51.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:StockholdersEquity █▇██▇▄▆▇▆▆▆▆▆▆▆▆▆▆▅▇▇▆▅▅▆▆▅▅▅▄▃▃▃▄▃▄▃▃▃▂▂▂▂▂▁▁3154.03046.83202.23155.03071.72736.62916.23086.82941.12927.02954.72982.42939.82913.12997.72972.02972.52913.52857.53045.73009.72957.02844.42877.52908.52899.92844.02771.92795.12681.12594.52544.22495.72624.02595.42699.42617.52579.02509.82454.92485.02488.72460.52478.82351.62302.2
us-gaap:AdditionalPaidInCapitalCommonStock █▇▆█▇▆▃▃▃▁█▇▇▆▆▆▅1873.41864.01857.41871.51866.61861.61837.31837.01833.11821.71871.81868.91864.21858.31857.01856.41852.0NA1846.7NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RetainedEarningsAccumulatedDeficit ██▇▇▆▆▆▆▆▆▅▆▅▅▄▄▄▄▄▄▄▄▄▃▃▃▃▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁2837.92734.92668.02529.22435.12344.92410.92423.12328.12278.72182.32277.62200.42124.11975.01946.51956.61899.41875.61910.41841.51860.41803.51749.81690.11588.41558.71489.21451.71387.41349.11295.21282.41252.81211.61282.11255.41248.81237.11200.71222.91267.41246.8NANANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▆▆██▇▄▅▅▅▃▂▁▁▂▅▅▅▄▄▆▆▅▄▅▅▆▆▆▇▆▆▆▆▇▇█▇▇▆▆▆▅▅250.5187.7372.5352.4323.570.6152.6153.5108.23.8-116.5-190.8-169.1-120.4107.6114.0106.989.262.8227.0229.4151.453.9104.0140.0226.9206.4214.1267.1228.1177.6187.8189.7323.1325.8364.0303.1265.1210.4191.5182.5145.0136.7NANANA
us-gaap:TreasuryStockValue ██▇▇▆▆▆▅▅▄▃▃▃▃▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁1808.41740.41696.31598.71554.11541.11485.21327.41328.91177.8983.5973.9956.3949.5942.5945.5943.6922.9928.2931.2897.0885.1847.1810.4752.5744.1752.4759.4748.8756.4762.9769.0770.1737.8729.7732.3723.8715.6723.1723.1703.5704.3720.1NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▄▄▄█▅▁▅▇▃▁▂▇▄▁▄▇▅▂▄█167.2141.8161.0320.8189.236.6179.0273.3113.437.284.9286.9148.131.4172.4282.4195.654.2177.6326.1NANA84.0251.718.584.2156.6240.7104.562.9202.0148.650.8-17.5203.6145.346.612.7-64.6183.678.524.298.677.527.5-120.0
us-gaap:NetCashProvidedByUsedInInvestingActivities ▃▃▂▁▃▃▅▁▄▁█▂▃▂▃▁▃▃▂▁-82.0-78.6-128.5-323.6-56.8-99.9193.3-289.863.9-279.3736.8-231.3-89.8-144.4-7.1-353.3-98.1-47.8-176.4-328.0NANA-59.7-354.9206.936.2-253.5-324.337.1-60.0-264.1-227.849.783.5-34.3-202.5-114.9-211.1-48.4100.5168.2-37.5-45.4-90.041.3-4.7
us-gaap:NetCashProvidedByUsedInFinancingActivities ▆▇▆█▆▇▄▇▆▁▇▇▇▇▇▇▇▇▇▇-90.9-71.7-143.451.7-93.7-8.5-314.2-5.7-168.8-610.6-47.5-47.5-68.4-7.6-19.6-25.6-34.4-32.1-33.3-41.7NANA-65.5-92.0-47.7-89.5-35.8-2.9-18.5-14.5-56.0-14.7-101.766.9-74.8-17.6-27.2-13.8-13.5-54.7256.0-60.5-33.324.2-17.117.6
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect ▅▅▄▅▅▄▅▅▅▁█-5.7-8.5-110.948.938.7-71.858.1-22.28.5-852.7772.7NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:DeferredIncomeTaxExpenseBenefit ▅▆▅▅▆▂▅▅▅▆▄▅▅▄█▄▇▄▃▇▄▅▆▆▇▄▆▆▇▆▆▇▆▆▁▇▆▄▃▆▅2.012.44.9-0.89.3-36.5-1.31.3-1.213.8-20.12.53.4-7.444.2-10.727.7-20.1-24.827.8-15.5-3.412.521.426.0-7.112.221.426.88.220.622.413.318.5-58.329.212.2-18.9-22.69.1-1.0NANANANANA
us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet ▇▆▆▂▆▅▅▁▆█▆▃▅▇▆▃▇▅▄▁▆▇▆▂▅▇▅▁▅▆▄▅▆▄▄█▄▅▂▄█▄▅▅▅▅34.219.023.9-34.022.012.81.3-52.420.845.015.1-29.69.238.919.8-29.935.82.0-8.4-49.819.537.117.1-41.52.537.37.0-50.113.017.6-8.78.820.8-2.1-12.051.6-5.113.9-41.4-8.745.0-11.56.55.97.213.6
us-gaap:NetCashProvidedByUsedInOperatingActivities ▄▄▄█▅▁▅▇▃▁▂▇▄▁▄▇▅▂▄█167.2141.8161.0320.8189.236.6179.0273.3113.437.284.9286.9148.131.4172.4282.4195.654.2177.6326.1NANA84.0251.718.584.2156.6240.7104.562.9202.0148.650.8-17.5203.6145.346.612.7-64.6183.678.524.298.677.527.5-120.0
us-gaap:NetIncomeLoss ▇▆█▇▆▁▆▇▅▇▇▆▆▅▄▃▅▄▂▆▃▅▅▅▇▅▆▅▅▄▅▅▄▅▁▄▃▄▄▂▂▄▅▄▃▄128.592.7164.6118.9115.2-40.0109.8118.974.0122.4123.6100.499.367.751.511.178.445.2-13.588.42.078.277.678.3120.754.989.954.982.654.670.161.353.466.2-55.040.420.849.749.3-9.7-31.829.358.452.32.341.8
us-gaap:ProfitLoss ▇▆█▆▆▁▆▆▅▇▇▆▆▅▄128.592.7164.6118.9115.2-40.0109.8118.974.0122.4123.6100.499.367.751.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ShareBasedCompensation ███▇▆▇▇▆▆▆▂▆▆▄▁▆▆▄▅▄▄▄▄▃▆▅▆▅▅▅▅▄▃▅▄▅▃▆▃▃▅▅▄▄▄▄5.45.65.74.94.55.04.74.14.44.21.34.54.63.00.84.24.13.23.53.02.72.82.91.94.23.34.03.83.83.53.53.22.13.63.03.52.24.12.32.43.73.62.72.73.12.8
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▃▃▂▁▃▃▅▁▄▁█▂▃▂▃▁▃▃▂▁-82.0-78.6-128.5-323.6-56.8-99.9193.3-289.863.9-279.3736.8-231.3-89.8-144.4-7.1-353.3-98.1-47.8-176.4-328.0NANA-59.7-354.9206.936.2-253.5-324.337.1-60.0-264.1-227.849.783.5-34.3-202.5-114.9-211.1-48.4100.5168.2-37.5-45.4-90.041.3-4.7
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▁▂▃▄▄▃▃▃▂▃▁▄▄▃▆▂▄▄▃▃▂▅▄▅▄▃▂▁▄▃▅▅▄▅█▄▃▃▅▄▂▂▄▂▂▂1.32.32.84.34.63.23.13.72.63.90.74.64.33.57.92.14.34.33.53.72.16.45.06.44.33.82.71.14.33.15.96.35.05.710.14.53.53.26.75.32.42.14.32.32.12.2
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▆▇▆█▆▇▄▇▆▁▇▇▇▇▇▇▇▇▇▇-90.9-71.7-143.451.7-93.7-8.5-314.2-5.7-168.8-610.6-47.5-47.5-68.4-7.6-19.6-25.6-34.4-32.1-33.3-41.7NANA-65.5-92.0-47.7-89.5-35.8-2.9-18.5-14.5-56.0-14.7-101.766.9-74.8-17.6-27.2-13.8-13.5-54.7256.0-60.5-33.324.2-17.117.6
us-gaap:ProceedsFromIssuanceOfLongTermDebt NANA0.0NANANANANANANANANANANANANANANANANANANANANANANANANANANA-0.90.00.0169.50.00.00.07.411.09.5301.93.01.97.60.0198.0
us-gaap:RepaymentsOfLongTermDebt NANA0.0174.9NANA0.00.0NANA0.0NANANANANANANA14.10.0NANA0.027.88.378.20.00.6NANA43.10.050.546.372.30.00.00.80.029.66.750.538.10.0NANA
us-gaap:PaymentsOfDividends ▁▁▁▁▁▁▅▁▁█▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁25.125.525.524.524.724.8120.923.824.5217.025.423.023.022.923.021.221.221.421.219.619.819.819.918.018.118.218.116.316.316.316.214.514.514.814.813.313.513.513.412.512.512.511.311.612.012.3
us-gaap:PaymentsForRepurchaseOfCommonStock ▃▂▄▂▁▂▆▁▅█▁▂▁▁▁▁▂▁▁▂▂▂▂▃▁▁▁▁▁▁▁▁▂▂▁▁73.345.3118.545.014.434.9163.60.0150.0250.013.518.911.713.60.09.223.44.60.437.719.148.442.061.815.08.50.013.70.46.30.05.947.125.20.010.0NANA1.7NANANA4.10.0NANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value3636383838404141434343424242434343444545444444444445454545454.54e-0546454.55e-0548
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value3536373838394040424242424242424342444444444443434444444444454.54e-0545444.49e-0547
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

us-gaap:StockCompensationPlan


Antidilutive
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-03-31
Value200000.0800000.0900000.0400000.0200000.0200000.0
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value3.582.554.493.153.03-1.042.83.01.823.012.922.362.341.591.210.261.851.06-0.322.070.051.821.791.782.731.242.041.251.881.241.61.41.211.49-1.240.910.461.111.1-0.21-0.70.651.291.160.050.88
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareDiluted


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value3.522.514.433.133.01-1.042.762.961.792.972.882.332.311.571.20.261.831.05-0.322.060.051.81.761.742.681.222.01.221.841.221.571.371.191.46-1.240.890.461.091.09-0.21-0.70.641.271.150.050.87
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Income Loss From Continuing Operations Per Basic Share

us-gaap:IncomeLossFromContinuingOperationsPerBasicShare

us-gaap:IncomeLossFromContinuingOperationsPerBasicShare


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value3.62.554.523.173.03-1.012.812.812.093.020.052.452.331.591.580.291.851.06-0.292.070.041.821.81.752.741.242.051.251.871.251.481.41.211.49-1.240.920.221.131.03-0.21-0.710.621.271.140.050.89
Percentage of IncomeLossFromContinuingOperationsPerBasicShare100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Income Loss From Continuing Operations Per Diluted Share

us-gaap:IncomeLossFromContinuingOperationsPerDilutedShare

us-gaap:IncomeLossFromContinuingOperationsPerDilutedShare


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value3.552.524.473.143.01-1.012.772.772.062.980.052.412.31.571.560.281.831.05-0.292.060.041.791.761.722.691.222.011.221.841.221.451.371.191.47-1.240.90.221.111.02-0.21-0.710.611.251.120.050.88
Percentage of IncomeLossFromContinuingOperationsPerDilutedShare100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Allocated Share Based Compensation Expense

us-gaap:AllocatedShareBasedCompensationExpense

us-gaap:AllocatedShareBasedCompensationExpense


Allocated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value5.45.65.74.94.55.04.74.14.44.24.34.04.63.00.84.24.13.23.53.02.72.82.91.94.23.34.03.83.83.53.53.22.13.63.03.52.24.12.73.52.63.42.53.12.7
Percentage of AllocatedShareBasedCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues0.40.40.40.40.40.50.40.30.40.30.40.30.30.20.10.30.30.30.30.20.20.20.20.20.30.30.30.30.30.30.30.30.20.30.30.30.20.40.20.30.30.40.30.40.4

Benefits Losses And Expenses

us-gaap:BenefitsLossesAndExpenses

us-gaap:BenefitsLossesAndExpenses


Benefits
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1133116910901101108111101124108410881070110110431242125012091316115512011287111712291119110511231144122111621190116511711140111511161091129011041116105110721126913796757730765687
Percentage of BenefitsLossesAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues87.691.184.088.188.3105.189.489.390.887.899.989.591.293.990.899.391.295.3102.690.0100.691.291.791.088.294.190.494.191.594.292.892.894.492.5109.095.499.093.794.4101.7107.095.590.990.999.692.1

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value191-92.1184147368-122.01081641782411977850-160.345189671-177.7868017527423375821.91211055959-80.063-93.21015810468-0.75.737-8.11296080
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues14.8-7.214.211.830.1-11.68.713.514.919.817.96.73.7-12.03.41.47.65.7-14.26.96.514.32.33.42.65.86.40.29.68.44.94.9-6.85.4-7.98.85.29.36.0-0.10.74.5-1.016.17.910.8

Deferred Policy Acquisition Cost Amortization Expense

us-gaap:DeferredPolicyAcquisitionCostAmortizationExpense

us-gaap:DeferredPolicyAcquisitionCostAmortizationExpense


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value244240239237237236233232230229227224288288280275264266263257254259251259262260266260259253251243232242241235233228250241181180178173163154
Percentage of DeferredPolicyAcquisitionCostAmortizationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues18.918.718.419.019.422.418.619.219.218.820.619.221.221.621.120.820.921.121.020.820.821.120.921.020.220.120.820.520.420.420.520.319.720.520.420.420.720.322.121.821.221.721.421.621.220.7

Gain Loss On Investments

us-gaap:GainLossOnInvestments

us-gaap:GainLossOnInvestments


Gain
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value3038643864-162.434141148-54.5234.0-23.42.5135.91.93.64.2-0.71.5-10.58.0129.4184.9224.4101.0138.1185.0-3.43.13.28.2133.3125.70.210
Percentage of GainLossOnInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues2.43.05.03.15.3-15.42.71.21.04.0-4.92.00.3-1.80.21.00.50.20.30.3-0.10.1-0.90.61.00.71.40.41.70.40.90.11.20.71.60.4-0.30.30.30.71.60.41.50.70.01.5

Income Loss From Continuing Operations

us-gaap:IncomeLossFromContinuingOperations

us-gaap:IncomeLossFromContinuingOperations


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value12992165119115-38.7110111851222.1104996767127845-12.2881.9787777120549055825464615366-55.3409.85046-9.7-32.42757512.242
Percentage of IncomeLossFromContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues10.07.212.89.69.4-3.78.89.27.110.10.28.97.35.15.00.96.23.6-1.07.10.26.46.56.39.34.27.04.36.54.45.35.14.55.6-4.73.50.94.54.1-0.9-3.83.36.96.40.35.7

us-gaap:IncomeLossFromContinuingOperations us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-0.7-0.7-1.2-1.1-1.2-1.2-2.2-2.3-2.2-2.3-1.9-2.0-1.7-2.0-2.1-2.0
Percentage of IncomeLossFromContinuingOperations-0.5-0.8-0.7-0.9-1.03.1-2.0-2.1-2.6-1.9-90.5-1.9-1.7-2.9-3.1-16.3
Percentage of Revenues-0.1-0.1-0.1-0.1-0.1-0.1-0.2-0.2-0.2-0.2-0.2-0.2-0.1-0.2-0.2-0.2
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302014-03-312013-12-312013-09-302013-03-312012-12-312012-09-30
Value4.60.67.27.74.3-13.26.73.13.73.6-3.61.94.12.17.0118.4104.610146.5
Percentage of IncomeLossFromContinuingOperations3.50.64.36.43.734.16.12.84.42.9-171.41.84.13.110.489.415.416.87.516.3-25.715.9
Percentage of Revenues0.40.00.60.60.4-1.20.50.30.30.3-0.30.20.30.20.50.80.70.90.40.91.20.6
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value159114207148143-53.91331301091481.1122119801228.911159-32.8124-7.1108991101528411670856886906387-119.748156960-25.0-57.63964672.9
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues12.48.916.011.911.7-5.110.610.79.212.20.110.58.86.19.20.78.84.7-2.610.0-0.68.88.39.011.86.59.05.56.75.57.07.55.47.4-10.14.21.36.25.3-2.3-6.74.77.88.40.4

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-09-302014-06-30
Value4.6-1.66.06.72.2-19.13.1-0.20.4-0.3-5.7-0.60.1-0.73.7135.43.93.83.3-0.51.9-10.41.7129.34.322
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest2.9-1.42.94.51.535.42.3-0.20.4-0.2-518.2-0.50.1-0.93.0156.24.96.6-11.62.77.01.8-10.51.58.211.06.126.0
Percentage of Revenues0.4-0.10.50.50.2-1.80.2-0.00.0-0.0-0.5-0.10.0-0.10.31.00.40.30.30.3-0.00.2-0.90.11.00.70.31.8
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxExpenseBenefit


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value3021412927-15.223192426-1.018201255-3.43213-20.635-9.030213331223220251723241222-51.1121.32017-9.0-27.39.618210.917
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues2.31.73.22.32.3-1.41.81.62.12.1-0.11.61.51.04.2-0.32.61.1-1.62.9-0.72.41.82.72.41.72.61.62.01.41.92.11.11.9-4.31.10.11.81.5-0.8-3.21.22.22.70.12.3

us-gaap:IncomeTaxExpenseBenefit us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value-0.2-0.1-0.4-0.3-0.3-0.3-0.7-0.5-0.6-0.6-0.4-0.5-0.5-0.5-1.1-1.2-1.1-1.2-0.8-1.0-0.8-0.9-1.0-1.0-1.3-0.9-5.0-0.9-0.9-0.91.01.0-2.2-1.00.80.8
Percentage of IncomeTaxExpenseBenefit-0.7-0.5-1.0-1.0-1.12.0-3.0-2.6-2.4-2.340.0-2.7-2.4-3.9-2.035.3-3.4-8.73.9-2.88.9-3.0-4.6-3.0-4.1-4.1-15.2-4.4-3.6-5.24.34.0-17.2-4.4-1.66.5
Percentage of Revenues-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.0-0.1-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.4-0.1-0.1-0.10.10.1-0.2-0.10.10.1
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value0.0-2.2-1.2-1.0-2.1-5.9-3.6-3.3-3.3-3.9-2.1-2.5-3.3-2.6-2.22.5-1.3-1.8-5.4-3.9-4.3-4.2-7.5-2.91.20.52.3-2.42.6-4.10.4-2.8-0.2-2.51.9-2.9
Percentage of IncomeTaxExpenseBenefit0.0-10.3-2.9-3.4-7.638.8-15.5-17.3-13.3-15.0210.0-13.4-15.9-20.3-4.0-73.5-4.0-13.026.2-10.947.8-14.0-34.7-8.73.82.37.0-11.810.3-23.61.7-11.3-1.6-11.1-3.7-23.6
Percentage of Revenues0.0-0.2-0.1-0.1-0.2-0.6-0.3-0.3-0.3-0.3-0.2-0.2-0.2-0.2-0.20.2-0.1-0.1-0.4-0.3-0.4-0.3-0.6-0.20.10.00.2-0.20.2-0.30.0-0.2-0.0-0.20.2-0.3
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Interest Expense Debt

us-gaap:InterestExpenseDebt

us-gaap:InterestExpenseDebt


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value8.58.58.59.89.49.49.49.49.39.411111112121212121212151414141415161616161616171415141516161710101111119.3
Percentage of InterestExpenseDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues0.70.70.70.80.80.90.70.80.80.81.01.00.90.90.90.91.01.01.01.01.31.21.21.21.11.21.31.31.31.31.41.41.51.21.31.31.41.41.41.61.31.21.41.51.51.2

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value12892164118115-40.010911874122123100996751117845-13.5882.0787778120548954825470615366-55.040204949-9.7-31.82958522.341
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues9.97.212.79.59.4-3.88.79.86.210.011.28.67.35.13.90.86.23.6-1.17.10.26.46.46.39.34.27.04.36.54.45.75.14.55.6-4.63.51.84.44.3-0.9-3.73.57.06.50.35.6

us-gaap:NetIncomeLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value3.9-0.16.26.73.1-14.83.60.81.51.3-62.80.21.6-0.13.59.14.33.47.55.72.14.5-5.22.97.97.17.25.1186.6126.510.08.9158.1
Percentage of NetIncomeLoss3.0-0.13.85.62.737.03.30.72.01.1-50.80.21.6-0.16.882.05.57.5-55.66.4105.05.8-6.73.76.512.98.09.321.912.118.110.618.713.4-28.520.0
Percentage of Revenues0.3-0.00.50.50.3-1.40.30.10.10.1-5.70.00.1-0.00.30.70.30.30.60.50.20.4-0.40.20.60.50.60.41.40.51.00.50.80.81.30.7
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-312012-09-30
Value4.60.67.47.84.3-13.66.53.13.73.6-21.32.23.41.95.9116.75.79.17.23.86.1-3.54.6118.8166.7198.4104.614146.5
Percentage of NetIncomeLoss3.60.64.56.63.734.05.92.65.02.9-17.22.23.42.811.5102.78.512.6-67.48.1190.07.8-4.55.99.416.018.512.223.815.415.57.526.4-25.816.1
Percentage of Revenues0.40.00.60.60.4-1.30.50.30.30.3-1.90.20.20.10.40.90.50.50.70.60.30.5-0.30.40.90.71.30.51.50.70.90.41.21.20.6
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value12892164118115-40.010911874122123100996751117845-13.5882.0787778120548954825470615366-55.040204949-9.7-31.82958522.341
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues9.97.212.79.59.4-3.88.79.86.210.011.28.67.35.13.90.86.23.6-1.17.10.26.46.46.39.34.27.04.36.54.45.75.14.55.6-4.63.51.84.44.3-0.9-3.73.57.06.50.35.6
Percentage of Revenues us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Investment Income

us-gaap:NetInvestmentIncome

us-gaap:NetInvestmentIncome


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value75767067576972686970696678827876727174676968706870706867676768656767706968686967616063616161
Percentage of NetInvestmentIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues5.86.05.45.44.76.65.85.75.85.86.35.75.86.25.95.85.75.65.95.55.75.65.85.55.55.45.45.35.35.45.55.55.75.75.96.06.16.16.16.17.17.27.67.68.08.2

us-gaap:NetInvestmentIncome us-gaap:StatementBusinessSegments

thg:CommercialLinesSegment


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value515146443746474444444745444542424140
Percentage of NetInvestmentIncome67.567.466.465.765.766.765.164.163.863.167.967.856.954.653.955.057.156.7
Percentage of Revenues3.94.03.63.63.14.43.83.63.73.64.33.93.33.43.23.23.33.2
Percentage of Revenues thg:CommercialLinesSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

thg:PersonalLinesSegment


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value212220191620211919191918181817171717
Percentage of NetInvestmentIncome28.828.829.128.828.629.229.028.528.328.127.427.423.022.222.823.224.124.1
Percentage of Revenues1.71.71.61.61.31.91.71.61.61.61.71.61.31.41.31.31.41.4
Percentage of Revenues thg:PersonalLinesSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AllOtherSegments


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value2.82.93.23.73.32.94.35.15.56.23.33.22.7
Percentage of NetInvestmentIncome3.73.84.65.55.74.25.97.47.98.84.84.83.4
Percentage of Revenues0.20.20.20.30.30.30.30.40.50.50.30.30.2
Percentage of Revenues us-gaap:AllOtherSegments0.00.00.00.00.00.00.00.00.00.00.00.00.0

Operating Income Loss

us-gaap:OperatingIncomeLoss

us-gaap:OperatingIncomeLoss


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value1378515012888117110126107109931121291161351311869-22.112994120124122119100132861028510210781102-104.562318577-8.2-47.349
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues10.66.611.610.37.311.18.810.48.99.08.49.79.58.810.11.09.45.5-1.810.57.79.810.39.99.27.710.36.88.06.88.48.96.98.7-8.85.42.87.66.8-0.7-5.56.0

us-gaap:OperatingIncomeLoss us-gaap:StatementBusinessSegments

thg:CommercialLinesSegment


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1042.2103625554737472805765826169284337
Percentage of OperatingIncomeLoss76.02.668.748.562.246.666.158.768.073.061.757.763.252.751.6213.736.354.1
Percentage of Revenues8.10.28.05.04.55.25.86.16.16.65.25.66.04.65.22.13.43.0
Percentage of Revenues thg:CommercialLinesSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

thg:PersonalLinesSegment


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value32815064326436503126364827344259479.9
Percentage of OperatingIncomeLoss23.596.133.850.036.755.432.839.729.624.439.242.721.029.531.1455.040.314.3
Percentage of Revenues2.56.43.95.12.76.12.94.12.62.23.34.12.02.63.24.53.80.8
Percentage of Revenues thg:PersonalLinesSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AllOtherSegments


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value0.71.1-3.71.91.0-2.41.32.02.52.8-0.8-0.5-1.7
Percentage of OperatingIncomeLoss0.51.3-2.51.51.1-2.01.21.62.32.6-0.9-0.4-1.3
Percentage of Revenues0.10.1-0.30.20.1-0.20.10.20.20.2-0.1-0.0-0.1
Percentage of Revenues us-gaap:AllOtherSegments0.00.00.00.00.00.00.00.00.00.00.00.00.0

Other Comprehensive Income Loss Net Of Tax

us-gaap:OtherComprehensiveIncomeLossNetOfTax

us-gaap:OtherComprehensiveIncomeLossNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value62-184.82028252-82.0-0.94510411874-21.7-48.7-228.0-6.47.11726-164.2-2.47897-50.1-36.0-86.920-7.7-53.03950-10.2-1.9-133.4-2.7-38.2603854189.037
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues4.9-14.41.52.320.7-7.8-0.13.78.79.76.7-1.9-3.6-17.1-0.50.51.42.1-13.1-0.26.47.9-4.2-2.9-6.71.6-0.6-4.23.14.1-0.8-0.2-11.3-0.2-3.25.33.44.91.70.84.4

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherNonoperatingIncomeExpense


Other
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302018-09-302018-06-302017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302015-12-312015-09-302015-06-302014-12-312014-09-302014-06-30
Value0-1600000.0-100000.0-2000000.0-1400000.0-1900000.0-2000000.0-2900000.0-5500000.0-1600000.0200000.02500000.0200000.0300000.0200000.0-400000.0100000.0400000.0-400000.0
Percentage of OtherNonoperatingIncomeExpense0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues0.0-0.1-0.0-0.2-0.1-0.2-0.1-0.2-0.4-0.10.00.20.00.00.0-0.00.00.0-0.0

Policyholder Benefits And Claims Incurred Net

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet


Policyholder
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value745781695709712728742705717699706676783785759878725766843692729699675690744773695755725750689695692683872708732661687734617511471454498431
Percentage of PolicyholderBenefitsAndClaimsIncurredNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues57.660.953.656.858.268.959.158.159.957.464.058.057.559.057.066.357.360.867.255.859.757.056.156.057.459.554.259.757.060.356.157.958.557.973.761.264.959.060.566.372.361.356.656.564.957.8

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Policyholder
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value0.90.81.61.41.51.52.92.82.82.92.32.52.2
Percentage of PolicyholderBenefitsAndClaimsIncurredNet0.10.10.20.20.20.20.40.40.40.40.30.40.3
Percentage of Revenues0.10.10.10.10.10.10.20.20.20.20.20.20.2
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.0

Premiums Earned Net

us-gaap:PremiumsEarnedNet

us-gaap:PremiumsEarnedNet


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1179116111541135109611411144112411111095108210711272126312441226118111811170116011451151113711501205121111881184117411631140112410901094108210711050103510471018770761748728697666
Percentage of PremiumsEarnedNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues91.290.589.090.889.6108.191.092.592.789.898.191.993.494.993.492.693.393.793.393.593.793.894.593.293.093.292.593.692.393.592.893.692.292.791.492.593.292.392.291.990.291.489.890.590.889.3

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value12892164118115-40.010911874122123100996751
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues9.97.212.79.59.4-3.88.79.86.210.011.28.67.35.13.9

Realized Investment Gains Losses

us-gaap:RealizedInvestmentGainsLosses

us-gaap:RealizedInvestmentGainsLosses


Realized
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value4.8-1.65.88.20.83.13.90.60.8-0.4-2.6-0.2-0.40.33.9147.73.35.54.34.3227.5121412235.2224.4133.1148.6217.2-1.85.0-0.59.7144.7197.13.613
Percentage of RealizedInvestmentGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues0.4-0.10.40.70.10.30.30.00.1-0.0-0.2-0.0-0.00.00.31.10.60.30.40.30.41.80.61.01.10.91.80.41.80.41.10.31.30.71.80.6-0.20.4-0.00.91.70.62.30.90.51.8

us-gaap:RealizedInvestmentGainsLosses us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Realized
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value4.8-1.64.55.00.83.13.90.60.8-0.3-4.8-0.21.8-0.24.3157.24.15.73.44.5227.65.91412234.6224.3133.9158.7175.9
Percentage of RealizedInvestmentGainsLosses100.0100.077.661.0100.0100.0100.0100.0100.075.0184.6100.0-450.0-66.7110.3103.493.5124.2103.679.1104.7101.8101.348.499.399.2100.888.5100.497.7104.6125.8102.0101.285.281.9
Percentage of Revenues0.4-0.10.30.40.10.30.30.00.1-0.0-0.4-0.00.1-0.00.31.10.60.30.50.30.41.90.60.51.10.91.90.41.80.31.10.31.30.71.50.5
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Revenues

us-gaap:Revenues

us-gaap:Revenues


Revenues
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1293128312971249122410561257121411981219110211661362133013321325126612601255124112221227120412331297129812851265127312431229120111821180118411571127112111351108853833833804768746
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value137281344813443133931283812277124901262712159119831239915624154031533415469153891479214490142201436314163140271379014041141441392513759139601396413643133781346313306134421348413330131181291312624126848981851485698042
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:ConsolidatedEntities

srt:ParentCompany


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-31
Value4144372240623804
Percentage of Assets30.829.832.824.6
Percentage of Assets30.829.832.824.6
Percentage of Assets srt:ParentCompany100.0100.0100.0100.0

us-gaap:Assets us-gaap:PropertyPlantAndEquipmentByType

thg:PropertyAndCasualty


Assetsus-gaap:
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value133331328412733121791238712238
Percentage of Assets99.299.299.299.299.298.7
Percentage of Assets99.299.299.299.299.298.7
Percentage of Assets thg:PropertyAndCasualty100.0100.0100.0100.0100.0100.0

thg:PropertyAndCasualtyInsurance


Assetsus-gaap:
Period End2021-06-302021-03-312020-12-31
Value136181334813333
Percentage of Assets99.299.399.2
Percentage of Assets99.299.399.2
Percentage of Assets thg:PropertyAndCasualtyInsurance100.0100.0100.0

Liabilities

us-gaap:Liabilities

us-gaap:Liabilities


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value10574104011024110238976695409574954092189056944512641124631242112471124171182011577113621131811153110701094611163112361102510915111881116910961107841091910810108181088910630105011033410114102296496602661095684
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets77.077.376.276.476.177.776.775.675.875.676.280.980.981.080.680.779.979.979.978.878.878.979.479.579.479.279.380.180.080.380.681.181.280.580.879.780.080.080.180.672.370.871.370.7

us-gaap:Liabilities us-gaap:ConsolidatedEntities

srt:ParentCompany


Liabilitiesus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-31
Value9428061107806
Percentage of Liabilities9.28.411.76.5
Percentage of Assets7.06.58.95.2
Percentage of Assets srt:ParentCompany22.721.727.321.2

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value137281344813443133931283812277124901262712159119831239915624154031533415469153891479214490142201436314163140271379014041141441392513759139601396413643133781346313306134421348413330131181291312624126848981851485698042
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilitiesAndStockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Liabilities
Period End2020-12-312019-12-312018-12-312017-12-31
Value4144372240623804
Percentage of LiabilitiesAndStockholdersEquity30.829.832.824.6
Percentage of Assets30.829.832.824.6
Percentage of Assets srt:ParentCompany100.0100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value315430463202315530712736291630862941292729542982293929132997297229722913285730453009295728442877290828992844277127952681259425442495262425952699261725792509245424852488246024782351230223581887
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets23.022.723.823.623.922.323.324.424.224.423.819.119.119.019.419.320.120.120.121.221.221.120.620.520.620.820.719.920.019.719.418.918.819.519.220.320.020.019.919.427.729.228.70.00.00.029.30.0

us-gaap:StockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Stockholders
Period End2020-12-312019-12-312018-12-312017-12-31
Value3202291629542997
Percentage of StockholdersEquity100.0100.0100.0100.0
Percentage of Assets23.823.323.819.4
Percentage of Assets srt:ParentCompany77.378.372.778.8

us-gaap:StockholdersEquity us-gaap:CumulativeEffectPeriodOfAdoption, us-gaap:StatementEquityComponents

srt:CumulativeEffectPeriodOfAdoptionAdjustedBalance, us-gaap:RetainedEarnings


Stockholders
Period End2021-03-312020-12-312020-06-302020-03-312019-12-312019-06-302019-03-312018-12-312017-12-31
Value273426682435234424102328227821802079
Percentage of StockholdersEquity89.883.379.385.782.679.277.973.869.4
Percentage of Assets20.319.819.019.119.319.119.017.613.4
Percentage of Assets srt:CumulativeEffectPeriodOfAdoptionAdjustedBalance us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value-54.2-54.9-55.6-59.9-61.0-62.2-63.4-81.8-84.1-86.3-88.6-95.2-97.1-98.0-79.5-95.5-97.8-100.2-102.5-73.8-75.3-77.0-78.6-78.9-80.6-80.7-84.3-71.1-72.7-74.3-76.1-88.7-90.6-94.7-96.6-82.2-83.8-85.3-86.8-76.6-78.3-79.9-81.6-74.2-75.7-77.3-78.9-108.7-25.9
Percentage of StockholdersEquity-1.7-1.8-1.7-1.9-2.0-2.3-2.2-2.6-2.9-2.9-3.0-3.2-3.3-3.4-2.7-3.2-3.3-3.4-3.6-2.4-2.5-2.6-2.8-2.7-2.8-2.8-3.0-2.6-2.6-2.8-2.9-3.5-3.6-3.6-3.7-3.0-3.2-3.3-3.5-3.1-3.2-3.2-3.3-3.0-3.2-3.4-3.3-5.80.0
Percentage of Assets-0.4-0.4-0.4-0.4-0.5-0.5-0.5-0.6-0.7-0.7-0.7-0.6-0.6-0.6-0.5-0.6-0.7-0.7-0.7-0.5-0.5-0.5-0.6-0.6-0.6-0.6-0.6-0.5-0.5-0.5-0.6-0.7-0.7-0.7-0.7-0.6-0.6-0.7-0.7-0.6-0.9-0.9-1.00.00.00.0-1.00.00.0
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value30424242841238413221623519290-27.2-74.0-48.80.3205228224205186321323246149197233327300293342308259284294431426449397352308277260224218277201145107-276.15.5
Percentage of StockholdersEquity9.78.013.413.112.54.97.47.66.53.1-0.9-2.5-1.70.06.97.77.67.06.510.610.78.35.36.98.011.310.610.612.311.510.011.211.816.416.416.615.213.712.311.310.59.08.911.28.66.34.6-14.60.0
Percentage of Assets2.21.83.23.13.01.11.71.91.60.8-0.2-0.5-0.30.01.31.51.51.41.32.22.31.81.11.41.62.42.22.12.52.31.92.12.23.23.23.43.02.72.42.22.92.62.50.00.00.01.30.00.0
Percentage of Assets us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value250187372352323701521531083.8-116.5-190.8-169.1-120.41071141068962227229151531041402262142672281771871893233253643032652101911821451362031266728-384.8
Percentage of StockholdersEquity7.96.211.611.210.52.65.25.03.70.1-3.9-6.4-5.8-4.13.63.83.63.12.27.57.65.11.93.64.87.87.79.68.56.87.47.612.312.613.511.610.38.47.87.35.85.68.25.42.91.2-20.4
Percentage of Assets1.81.42.82.62.50.61.21.20.90.0-0.9-1.2-1.1-0.80.70.70.70.60.41.61.61.10.40.71.01.61.51.91.71.31.41.42.42.42.72.32.11.71.52.01.71.60.00.00.00.40.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value1873186418571871186618611837183718331821187118681864185818571856185218471846183818351829183318331830182818301827182418211830182917931785178717851782178017841785178217801796179817961799180818031822
Percentage of StockholdersEquity59.461.258.059.360.868.063.059.562.362.263.362.763.463.861.962.562.363.464.660.461.061.964.563.762.963.064.465.965.367.970.571.971.868.068.966.168.169.071.172.771.771.573.072.676.478.176.795.60.0
Percentage of Assets13.613.913.814.014.515.214.714.515.115.215.112.012.112.112.012.112.512.713.012.813.013.013.313.112.913.113.313.113.113.413.713.613.513.313.313.413.613.814.114.119.820.921.00.00.00.022.50.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value28372734266825292435234424102423232822782182227722002124197519461956189918751910184118601803174916901588155814891451138713491295128212521211128212551248123712001222126712461201116311731141949946
Percentage of StockholdersEquity90.089.883.380.279.385.782.778.579.277.973.976.474.872.965.965.565.865.265.662.761.262.963.460.858.154.854.853.751.951.752.050.951.447.746.747.548.048.449.348.949.250.950.748.549.551.048.450.30.0
Percentage of Assets20.720.319.818.919.019.119.319.219.119.017.614.614.313.912.812.613.213.113.213.313.013.313.112.511.911.411.310.710.410.210.19.69.69.39.09.69.69.79.89.513.614.914.50.00.00.014.20.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashAndCashEquivalentsAtCarryingValue


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value1061121202311821432151571791681020117244258376227317257282315361406338385583403373509606476486602690691564462520628820922721218290271260209316397210
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.80.80.91.71.41.21.71.21.51.48.20.81.61.72.41.52.11.82.02.22.62.92.52.74.12.92.73.74.33.53.64.55.25.14.23.54.04.96.57.38.02.63.40.00.00.03.90.00.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:ConsolidatedEntities

srt:ParentCompany


Cash
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value151282732108.6
Percentage of CashAndCashEquivalentsAtCarryingValue12.95.781.18.73.62.5
Percentage of Assets0.10.16.70.20.10.1
Percentage of Assets srt:ParentCompany0.40.320.40.90.00.0

Investments In Affiliates Subsidiaries Associates And Joint Ventures

us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures us-gaap:ConsolidatedEntities

us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures

srt:ParentCompany


Investments
Period End2020-12-312019-12-312018-12-312017-12-31
Value3718335228003455
Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures100.0100.0100.0100.0
Percentage of Assets27.726.822.622.3
Percentage of Assets srt:ParentCompany89.790.168.990.8

Goodwill

us-gaap:Goodwill

us-gaap:Goodwill


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value178178178178178178178178178178178178192192192185185184184185185185186184184184184184185185184184184184184184184184185200178178179171
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.31.31.31.31.41.51.41.41.51.51.41.11.21.31.21.21.31.31.31.31.31.31.31.31.31.31.31.31.31.41.41.41.41.41.41.41.41.41.51.62.02.12.12.1

Equity Securities Fv Ni

us-gaap:EquitySecuritiesFvNi

us-gaap:EquitySecuritiesFvNi


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value618641598490458447575570531504464574576
Percentage of EquitySecuritiesFvNi100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.54.84.53.73.63.64.64.54.44.23.73.73.7

us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel3


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1.21.21.12.52.32.12.12.12.11.11.11.11.1
Percentage of EquitySecuritiesFvNi0.20.20.20.50.50.50.40.40.40.20.20.20.2
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:FairValueInputsLevel30.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueMeasuredAtNetAssetValuePerShare


Equity
Period End2020-12-312019-12-312018-12-312017-12-31
Value52512329
Percentage of EquitySecuritiesFvNi8.89.05.15.2
Percentage of Assets0.40.40.20.2
Percentage of Assets us-gaap:FairValueMeasuredAtNetAssetValuePerShare0.00.00.00.0

us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value613635593488456444573568529503463573567
Percentage of EquitySecuritiesFvNi99.199.199.199.599.599.599.699.699.699.899.899.898.4
Percentage of Assets4.54.74.43.63.63.64.64.54.44.23.73.73.7
Percentage of Assets us-gaap:FairValueInputsLevel1 us-gaap:FairValueMeasurementsRecurring0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value5.65.65.52.52.32.12.12.12.11.11.11.11.1
Percentage of EquitySecuritiesFvNi0.90.90.90.50.50.50.40.40.40.20.20.20.2
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:FairValueInputsLevel3 us-gaap:FairValueMeasurementsRecurring0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:ValuationTechnique

us-gaap:FairValueInputsLevel3, us-gaap:EquitySecurities, thg:InternalModelPricingApproachValuationTechnique


Equity
Period End2021-06-302021-03-312020-12-312019-12-31
Value4.44.44.41.0
Percentage of EquitySecuritiesFvNi0.70.70.70.2
Percentage of Assets0.00.00.00.0
Percentage of Assets us-gaap:FairValueInputsLevel3 us-gaap:EquitySecurities thg:InternalModelPricingApproachValuationTechnique0.00.00.00.0

us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value618641598490458447575570531504464575568
Percentage of EquitySecuritiesFvNi100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.098.6
Percentage of Assets4.54.84.53.73.63.64.64.54.44.23.73.73.7
Percentage of Assets us-gaap:FairValueMeasurementsRecurring0.00.00.00.00.00.00.00.00.00.00.00.00.0

Other Assets

us-gaap:OtherAssets

us-gaap:OtherAssets


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value484461445419447417402384431417371330539524504486509485479476525512493469514504486497542534526544535524511531513496515527428383398351
Percentage of OtherAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.53.43.33.13.53.43.23.03.53.53.02.13.53.43.33.23.43.43.43.33.73.73.63.33.63.63.53.63.93.93.94.04.03.93.84.03.93.84.14.24.84.54.64.4

us-gaap:OtherAssets us-gaap:ConsolidatedEntities

srt:ParentCompany


Other
Period End2020-12-312019-12-312018-12-312017-12-31
Value2.93.2342.6
Percentage of OtherAssets0.70.89.30.5
Percentage of Assets0.00.00.30.0
Percentage of Assets srt:ParentCompany0.10.10.90.1

Accrued Income Taxes Current

us-gaap:AccruedIncomeTaxesCurrent us-gaap:ConsolidatedEntities

us-gaap:AccruedIncomeTaxesCurrent

srt:ParentCompany


Accrued
Period End2020-12-312019-12-312018-12-312017-12-31
Value2.73.5463.2
Percentage of AccruedIncomeTaxesCurrent100.0100.0100.0100.0
Percentage of Assets0.00.00.40.0
Percentage of Assets srt:ParentCompany0.10.11.20.1

Deferred Income Tax Liabilities Net

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:DeferredIncomeTaxLiabilitiesNet


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-31
Value836497847451
Percentage of DeferredIncomeTaxLiabilitiesNet100.0100.0100.0100.0100.0100.0
Percentage of Assets0.60.50.70.60.60.4

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value315430463202315530712736291630862941292729542982293929132997297229722913285730453009295728442877290828992844277127952681259425442495262425952699261725792509245424852488246024782351230223581887
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets23.022.723.823.623.922.323.324.424.224.423.819.119.119.019.419.320.120.120.121.221.221.120.620.520.620.820.719.920.019.719.418.918.819.519.220.320.020.019.919.427.729.228.70.00.00.029.30.0

us-gaap:StockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Stockholders
Period End2020-12-312019-12-312018-12-312017-12-31
Value3202291629542997
Percentage of StockholdersEquity100.0100.0100.0100.0
Percentage of Assets23.823.323.819.4
Percentage of Assets srt:ParentCompany77.378.372.778.8

us-gaap:StockholdersEquity us-gaap:CumulativeEffectPeriodOfAdoption, us-gaap:StatementEquityComponents

srt:CumulativeEffectPeriodOfAdoptionAdjustedBalance, us-gaap:RetainedEarnings


Stockholders
Period End2021-03-312020-12-312020-06-302020-03-312019-12-312019-06-302019-03-312018-12-312017-12-31
Value273426682435234424102328227821802079
Percentage of StockholdersEquity89.883.379.385.782.679.277.973.869.4
Percentage of Assets20.319.819.019.119.319.119.017.613.4
Percentage of Assets srt:CumulativeEffectPeriodOfAdoptionAdjustedBalance us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value-54.2-54.9-55.6-59.9-61.0-62.2-63.4-81.8-84.1-86.3-88.6-95.2-97.1-98.0-79.5-95.5-97.8-100.2-102.5-73.8-75.3-77.0-78.6-78.9-80.6-80.7-84.3-71.1-72.7-74.3-76.1-88.7-90.6-94.7-96.6-82.2-83.8-85.3-86.8-76.6-78.3-79.9-81.6-74.2-75.7-77.3-78.9-108.7-25.9
Percentage of StockholdersEquity-1.7-1.8-1.7-1.9-2.0-2.3-2.2-2.6-2.9-2.9-3.0-3.2-3.3-3.4-2.7-3.2-3.3-3.4-3.6-2.4-2.5-2.6-2.8-2.7-2.8-2.8-3.0-2.6-2.6-2.8-2.9-3.5-3.6-3.6-3.7-3.0-3.2-3.3-3.5-3.1-3.2-3.2-3.3-3.0-3.2-3.4-3.3-5.80.0
Percentage of Assets-0.4-0.4-0.4-0.4-0.5-0.5-0.5-0.6-0.7-0.7-0.7-0.6-0.6-0.6-0.5-0.6-0.7-0.7-0.7-0.5-0.5-0.5-0.6-0.6-0.6-0.6-0.6-0.5-0.5-0.5-0.6-0.7-0.7-0.7-0.7-0.6-0.6-0.7-0.7-0.6-0.9-0.9-1.00.00.00.0-1.00.00.0
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value30424242841238413221623519290-27.2-74.0-48.80.3205228224205186321323246149197233327300293342308259284294431426449397352308277260224218277201145107-276.15.5
Percentage of StockholdersEquity9.78.013.413.112.54.97.47.66.53.1-0.9-2.5-1.70.06.97.77.67.06.510.610.78.35.36.98.011.310.610.612.311.510.011.211.816.416.416.615.213.712.311.310.59.08.911.28.66.34.6-14.60.0
Percentage of Assets2.21.83.23.13.01.11.71.91.60.8-0.2-0.5-0.30.01.31.51.51.41.32.22.31.81.11.41.62.42.22.12.52.31.92.12.23.23.23.43.02.72.42.22.92.62.50.00.00.01.30.00.0
Percentage of Assets us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value250187372352323701521531083.8-116.5-190.8-169.1-120.41071141068962227229151531041402262142672281771871893233253643032652101911821451362031266728-384.8
Percentage of StockholdersEquity7.96.211.611.210.52.65.25.03.70.1-3.9-6.4-5.8-4.13.63.83.63.12.27.57.65.11.93.64.87.87.79.68.56.87.47.612.312.613.511.610.38.47.87.35.85.68.25.42.91.2-20.4
Percentage of Assets1.81.42.82.62.50.61.21.20.90.0-0.9-1.2-1.1-0.80.70.70.70.60.41.61.61.10.40.71.01.61.51.91.71.31.41.42.42.42.72.32.11.71.52.01.71.60.00.00.00.40.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value1873186418571871186618611837183718331821187118681864185818571856185218471846183818351829183318331830182818301827182418211830182917931785178717851782178017841785178217801796179817961799180818031822
Percentage of StockholdersEquity59.461.258.059.360.868.063.059.562.362.263.362.763.463.861.962.562.363.464.660.461.061.964.563.762.963.064.465.965.367.970.571.971.868.068.966.168.169.071.172.771.771.573.072.676.478.176.795.60.0
Percentage of Assets13.613.913.814.014.515.214.714.515.115.215.112.012.112.112.012.112.512.713.012.813.013.013.313.112.913.113.313.113.113.413.713.613.513.313.313.413.613.814.114.119.820.921.00.00.00.022.50.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value28372734266825292435234424102423232822782182227722002124197519461956189918751910184118601803174916901588155814891451138713491295128212521211128212551248123712001222126712461201116311731141949946
Percentage of StockholdersEquity90.089.883.380.279.385.782.778.579.277.973.976.474.872.965.965.565.865.265.662.761.262.963.460.858.154.854.853.751.951.752.050.951.447.746.747.548.048.449.348.949.250.950.748.549.551.048.450.30.0
Percentage of Assets20.720.319.818.919.019.119.319.219.119.017.614.614.313.912.812.613.213.113.213.313.013.313.112.511.911.411.310.710.410.210.19.69.69.39.09.69.69.79.89.513.614.914.50.00.00.014.20.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Additional Paid In Capital Common Stock

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:AdditionalPaidInCapitalCommonStock


Additional
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-31
Value187318641857187118661861183718371833182118711868186418581857185618521846
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets13.613.913.814.014.515.214.714.515.115.215.112.012.112.112.012.112.513.0

us-gaap:AdditionalPaidInCapitalCommonStock us-gaap:ConsolidatedEntities

srt:ParentCompany


Additional
Period End2020-12-312019-12-312018-12-312017-12-31
Value1857183718711857
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0
Percentage of Assets13.814.715.112.0
Percentage of Assets srt:ParentCompany44.849.446.148.8

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value28372734266825292435234424102423232822782182227722002124197519461956189918751910184118601803174916901588155814891451138713491295128212521211128212551248123712001222126712461141
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets20.720.319.818.919.019.119.319.219.119.017.614.614.313.912.812.613.213.113.213.313.013.313.112.511.911.411.310.710.410.210.19.69.69.39.09.69.69.79.89.513.614.914.514.2

us-gaap:RetainedEarningsAccumulatedDeficit us-gaap:ConsolidatedEntities

srt:ParentCompany


Retained
Period End2020-12-312019-12-312018-12-312017-12-31
Value2668241021821975
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0
Percentage of Assets19.819.317.612.8
Percentage of Assets srt:ParentCompany64.464.853.751.9

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value250187372352323701521531083.8-116.5-190.8-169.1-120.410711410689622272291515310414022620621426722817718718932332536430326521019118214513628
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.81.42.82.62.50.61.21.20.90.0-0.9-1.2-1.1-0.80.70.70.70.60.41.61.61.10.40.71.01.61.51.51.91.71.31.41.42.42.42.72.32.11.71.52.01.71.60.4

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:ConsolidatedEntities

srt:ParentCompany


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-31
Value372152-116.5107
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0
Percentage of Assets2.81.2-0.90.7
Percentage of Assets srt:ParentCompany9.04.1-2.92.8

Treasury Stock Value

us-gaap:TreasuryStockValue

us-gaap:TreasuryStockValue


Treasury
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1808174016961598155415411485132713281177983973956949942945943922928931897885847810752744752759748756762769770737729732723715723723703704720620
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets13.212.912.611.912.112.611.910.510.99.87.96.26.26.26.16.16.46.46.56.56.36.36.15.85.35.35.55.45.45.55.75.75.85.55.45.55.55.55.75.77.88.38.47.7

us-gaap:TreasuryStockValue us-gaap:ConsolidatedEntities

srt:ParentCompany


Treasury
Period End2020-12-312019-12-312018-12-312017-12-31
Value16961485983942
Percentage of TreasuryStockValue100.0100.0100.0100.0
Percentage of Assets12.611.97.96.1
Percentage of Assets srt:ParentCompany40.939.924.224.8

us-gaap:TreasuryStockValue us-gaap:StatementEquityComponents

us-gaap:TreasuryStock


Treasury
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value180817401696159815541541-1485.2132713281177983973956949942-928.2
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0-100.0100.0100.0100.0100.0100.0100.0100.0100.0-100.0
Percentage of Assets13.212.912.611.912.112.6-11.910.510.99.87.96.26.26.26.1-6.5
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value16714116132018936179273113378428614831172282195541773268425118841562401046220214850-17.52031454612-64.61837824987727-120.0
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues12.911.012.425.715.53.514.222.59.53.17.724.610.92.412.921.315.44.314.226.37.020.41.46.512.219.08.25.116.412.44.3-1.517.212.64.11.1-5.716.69.22.911.89.63.6-16.1

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-82.0-78.6-128.5-323.6-56.8-99.9193-289.863-279.3736-231.3-89.8-144.4-7.1-353.3-98.1-47.8-176.4-328.0-59.7-354.920636-253.5-324.337-60.0-264.1-227.84983-34.3-202.5-114.9-211.1-48.4100168-37.5-45.4-90.041-4.7
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-6.3-6.1-9.9-25.9-4.6-9.515.4-23.95.3-22.966.8-19.8-6.6-10.8-0.5-26.7-7.7-3.8-14.1-26.4-5.0-28.816.02.8-19.7-25.62.9-4.8-21.5-19.04.27.1-2.9-17.5-10.2-18.8-4.39.119.7-4.5-5.4-11.25.4-0.6

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-90.9-71.7-143.451-93.7-8.5-314.2-5.7-168.8-610.6-47.5-47.5-68.4-7.6-19.6-25.6-34.4-32.1-33.3-41.7-65.5-92.0-47.7-89.5-35.8-2.9-18.5-14.5-56.0-14.7-101.766-74.8-17.6-27.2-13.8-13.5-54.7256-60.5-33.324-17.117
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-7.0-5.6-11.14.1-7.7-0.8-25.0-0.5-14.1-50.1-4.3-4.1-5.0-0.6-1.5-1.9-2.7-2.5-2.7-3.4-5.4-7.5-3.7-6.9-2.8-0.2-1.5-1.2-4.6-1.2-8.65.7-6.3-1.5-2.4-1.2-1.2-4.930.0-7.3-4.03.0-2.22.4

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-5.7-8.5-110.94838-71.858-22.28.5-852.7772
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-0.4-0.7-8.63.93.2-6.84.6-1.80.7-69.970.1

Deferred Income Tax Expense Benefit

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:DeferredIncomeTaxExpenseBenefit


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value2.0124.9-0.89.3-36.5-1.31.3-1.213-20.12.53.4-7.444-10.727-20.1-24.827-15.5-3.4122126-7.11221268.220221318-58.32912-18.9-22.69.1-1.0
Percentage of DeferredIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Increase Decrease In Other Operating Capital Net

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value341923-34.022121.3-52.4204515-29.69.23819-29.9352.0-8.4-49.8193717-41.52.5377.0-50.11317-8.78.820-2.1-12.051-5.113-41.4-8.745-11.56.55.97.213
Percentage of IncreaseDecreaseInOtherOperatingCapitalNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value16714116132018936179273113378428614831172282195541773268425118841562401046220214850-17.52031454612-64.61837824987727-120.0
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues12.911.012.425.715.53.514.222.59.53.17.724.610.92.412.921.315.44.314.226.37.020.41.46.512.219.08.25.116.412.44.3-1.517.212.64.11.1-5.716.69.22.911.89.63.6-16.1

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value12892164118115-40.010911874122123100996751117845-13.5882.0787778120548954825470615366-55.040204949-9.7-31.82958522.341
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues9.97.212.79.59.4-3.88.79.86.210.011.28.67.35.13.90.86.23.6-1.17.10.26.46.46.39.34.27.04.36.54.45.75.14.55.6-4.63.51.84.44.3-0.9-3.73.57.06.50.35.6

us-gaap:NetIncomeLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value3.9-0.16.26.73.1-14.83.60.81.51.3-62.80.21.6-0.13.59.14.33.47.55.72.14.5-5.22.97.97.17.25.1186.6126.510.08.9158.1
Percentage of NetIncomeLoss3.0-0.13.85.62.737.03.30.72.01.1-50.80.21.6-0.16.882.05.57.5-55.66.4105.05.8-6.73.76.512.98.09.321.912.118.110.618.713.4-28.520.0
Percentage of Revenues0.3-0.00.50.50.3-1.40.30.10.10.1-5.70.00.1-0.00.30.70.30.30.60.50.20.4-0.40.20.60.50.60.41.40.51.00.50.80.81.30.7
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-312012-09-30
Value4.60.67.47.84.3-13.66.53.13.73.6-21.32.23.41.95.9116.75.79.17.23.86.1-3.54.6118.8166.7198.4104.614146.5
Percentage of NetIncomeLoss3.60.64.56.63.734.05.92.65.02.9-17.22.23.42.811.5102.78.512.6-67.48.1190.07.8-4.55.99.416.018.512.223.815.415.57.526.4-25.816.1
Percentage of Revenues0.40.00.60.60.4-1.30.50.30.30.3-1.90.20.20.10.40.90.50.50.70.60.30.5-0.30.40.90.71.30.51.50.70.90.41.21.20.6
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value12892164118115-40.010911874122123100996751117845-13.5882.0787778120548954825470615366-55.040204949-9.7-31.82958522.341
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues9.97.212.79.59.4-3.88.79.86.210.011.28.67.35.13.90.86.23.6-1.17.10.26.46.46.39.34.27.04.36.54.45.75.14.55.6-4.63.51.84.44.3-0.9-3.73.57.06.50.35.6
Percentage of Revenues us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value12892164118115-40.010911874122123100996751
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues9.97.212.79.59.4-3.88.79.86.210.011.28.67.35.13.9

Share Based Compensation

us-gaap:ShareBasedCompensation

us-gaap:ShareBasedCompensation


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value5.45.65.74.94.55.04.74.14.44.21.34.54.63.00.84.24.13.23.53.02.72.82.91.94.23.34.03.83.83.53.53.22.13.63.03.52.24.12.32.43.73.62.72.73.12.8
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-82.0-78.6-128.5-323.6-56.8-99.9193-289.863-279.3736-231.3-89.8-144.4-7.1-353.3-98.1-47.8-176.4-328.0-59.7-354.920636-253.5-324.337-60.0-264.1-227.84983-34.3-202.5-114.9-211.1-48.4100168-37.5-45.4-90.041-4.7
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-6.3-6.1-9.9-25.9-4.6-9.515.4-23.95.3-22.966.8-19.8-6.6-10.8-0.5-26.7-7.7-3.8-14.1-26.4-5.0-28.816.02.8-19.7-25.62.9-4.8-21.5-19.04.27.1-2.9-17.5-10.2-18.8-4.39.119.7-4.5-5.4-11.25.4-0.6

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.32.32.84.34.63.23.13.72.63.90.74.64.33.57.92.14.34.33.53.72.16.45.06.44.33.82.71.14.33.15.96.35.05.7104.53.53.26.75.32.42.14.32.32.12.2
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-90.9-71.7-143.451-93.7-8.5-314.2-5.7-168.8-610.6-47.5-47.5-68.4-7.6-19.6-25.6-34.4-32.1-33.3-41.7-65.5-92.0-47.7-89.5-35.8-2.9-18.5-14.5-56.0-14.7-101.766-74.8-17.6-27.2-13.8-13.5-54.7256-60.5-33.324-17.117
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-7.0-5.6-11.14.1-7.7-0.8-25.0-0.5-14.1-50.1-4.3-4.1-5.0-0.6-1.5-1.9-2.7-2.5-2.7-3.4-5.4-7.5-3.7-6.9-2.8-0.2-1.5-1.2-4.6-1.2-8.65.7-6.3-1.5-2.4-1.2-1.2-4.930.0-7.3-4.03.0-2.22.4

Proceeds From Issuance Of Long Term Debt

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:ProceedsFromIssuanceOfLongTermDebt


Proceeds
Period End2020-12-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.0-0.90.00.01690.00.00.07.4119.53013.01.97.60.0198
Percentage of ProceedsFromIssuanceOfLongTermDebt0.0100.00.00.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt


Repayments
Period End2020-12-312020-09-302019-12-312019-09-302018-12-312016-12-312016-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value0.01740.00.00.0140.00.0278.3780.00.6430.05046720.00.00.80.0296.750380.0
Percentage of RepaymentsOfLongTermDebt0.0100.00.00.00.0100.00.00.0100.0100.0100.00.0100.0100.00.0100.0100.0100.00.00.0100.00.0100.0100.0100.0100.00.0

Payments Of Dividends

us-gaap:PaymentsOfDividends

us-gaap:PaymentsOfDividends


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2525252424241202324217252323222321212121191919191818181816161616141414141313131312121211111212
Percentage of PaymentsOfDividends100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Payments For Repurchase Of Common Stock

us-gaap:PaymentsForRepurchaseOfCommonStock

us-gaap:PaymentsForRepurchaseOfCommonStock


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-312010-12-312010-09-302010-03-302009-12-08
Value73451184514341630.0150250131811130.09.2234.60.43719484261158.50.0130.46.30.05.947250.010.01.74.10.0105105
Percentage of PaymentsForRepurchaseOfCommonStock100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0

Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value97.8797.0393.6493.5393.4793.6787.8889.388.7287.9385.7584.9384.483.7375.5377.7275.6875.168.6368.0167.3660.6356.5752.2552.6352.4246.6146.1746.145.6141.1840.9140.7439.5238.2838.0638.0738.0638.5738.638.6238.6139.2239.16
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value9751255243255211202
Percentage of DeferredTaxLiabilities100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsNet


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1731551642087673116377165082355130138123131146145200239263288238267206271265260215173174177228
Percentage of DeferredTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Unrecognized Tax Benefits

us-gaap:UnrecognizedTaxBenefits

us-gaap:UnrecognizedTaxBenefits


Unrecognized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value900000.01300000.03000000.03000000.02700000.03000000.01300000.01400000.0800000.0800000.0800000.0800000.0800000.0
Percentage of UnrecognizedTaxBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:AcceleratedShareRepurchasesFinalSettlementOfSharesReceived us-gaap:ShareRepurchaseProgram

thg:AcceleratedShareRepurchasesFinalSettlementOfSharesReceived

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreements


Accelerated
Period End2021-01-29
Value45000.0
Percentage of AcceleratedShareRepurchasesFinalSettlementOfSharesReceived100.0

thg:AcceleratedShareRepurchasesFinalSettlementOfSharesReceived us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreements, us-gaap:SubsequentEvent


Accelerated
Period End2021-01-29
Value45000.0
Percentage of AcceleratedShareRepurchasesFinalSettlementOfSharesReceived100.0

thg:AcceleratedShareRepurchasesInitialDeliveryOfSharesReceived us-gaap:ShareRepurchaseProgram

thg:AcceleratedShareRepurchasesInitialDeliveryOfSharesReceived

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreement


Accelerated
Period End2020-10-29
Value800000.0
Percentage of AcceleratedShareRepurchasesInitialDeliveryOfSharesReceived100.0

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreements


Accelerated
Period End2020-10-29
Value800000.0
Percentage of AcceleratedShareRepurchasesInitialDeliveryOfSharesReceived100.0

thg:AmortizationOfDefinedBenefitPlanCosts

thg:AmortizationOfDefinedBenefitPlanCosts


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value0.90.81.51.51.51.52.92.82.92.82.42.52.32.53.53.53.53.52.42.5
Percentage of AmortizationOfDefinedBenefitPlanCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:DebtSecuritiesAvailableForSaleMeasurementInput1 us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:MeasurementInputType, us-gaap:ValuationTechnique

thg:DebtSecuritiesAvailableForSaleMeasurementInput1

us-gaap:FairValueInputsLevel3, us-gaap:CommercialMortgageBackedSecurities, thg:MeasurementInputDiscountRateForAboveMarketCoupon, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value00.00500.0050000.0050
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.0100.00.0100.00.00.00.0100.00.0

us-gaap:FairValueInputsLevel3, us-gaap:CorporateDebtSecurities, thg:MeasurementInputDiscountForCreditStress, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2020-09-30
Value-0.01
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.0

us-gaap:FairValueInputsLevel3, us-gaap:CorporateDebtSecurities, thg:MeasurementInputDiscountForSmallIssueSize, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value00.0250000.025
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.0500.00.00.00.0500.0

us-gaap:FairValueInputsLevel3, us-gaap:CorporateDebtSecurities, thg:MeasurementInputDiscountRateForAboveMarketCoupon, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value00.0030000.003
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.060.00.00.00.060.0

thg:DebtSecuritiesAvailableForSaleMeasurementInput1 us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:MeasurementInputType, us-gaap:ValuationTechnique

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:CommercialMortgageBackedSecurities, thg:MeasurementInputDiscountForCreditStress, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2020-12-312020-09-302020-06-302020-03-31
Value-0.01-0.008-0.0030.023
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.00.00.0460.0

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:CommercialMortgageBackedSecurities, thg:MeasurementInputDiscountForSmallIssueSize, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value00.0270000.0270000.0270
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.0540.00.00.00.0540.00.00.00.0540.00.0

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:CommercialMortgageBackedSecurities, thg:MeasurementInputDiscountRateForAboveMarketCoupon, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value00.0050000.0050000.0050
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.0100.00.00.00.0100.00.00.00.0100.00.0

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:CommercialMortgageBackedSecurities, thg:MeasurementInputDiscountRateForLeaseStructure, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value00.0030000.0030000.0030
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.060.00.00.00.060.00.00.00.060.00.0

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:CorporateDebtSecurities, thg:MeasurementInputDiscountForCreditStress, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2020-09-30
Value-0.01
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.0

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:CorporateDebtSecurities, thg:MeasurementInputDiscountForSmallIssueSize, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value00.0250000.025
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.0500.00.00.00.0500.0

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:CorporateDebtSecurities, thg:MeasurementInputDiscountRateForAboveMarketCoupon, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value00.0030000.003
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.060.00.00.00.060.0

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:MunicipalBonds, thg:MeasurementInputDiscountForCreditStress, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-03-312018-12-31
Value00.002-0.0040-0.0210.0270.0130
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.040.00.00.00.0540.0260.00.0

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:MunicipalBonds, thg:MeasurementInputDiscountForSmallIssueSize, us-gaap:ValuationTechniqueDiscountedCashFlow


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-0.0010.05-0.00100.0070.044000.010.0330.002
Percentage of DebtSecuritiesAvailableForSaleMeasurementInput10.01000.00.00.00.0880.00.00.00.0660.00.0

thg:FeesCommissionsAndOtherIncome

thg:FeesCommissionsAndOtherIncome


Fees
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value6.97.27.69.16.36.86.67.05.96.05.95.57.55.95.95.66.7
Percentage of FeesCommissionsAndOtherIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:GainLossOnInvestmentsFromContinuingOperations

thg:GainLossOnInvestmentsFromContinuingOperations


Gain
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value3137653763-161.634141248-54.5233.7-22.90.613
Percentage of GainLossOnInvestmentsFromContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:ImpairmentsOnFixedMaturitiesCreditRelatedLosses

thg:ImpairmentsOnFixedMaturitiesCreditRelatedLosses


Impairments
Period End2020-12-312020-03-31
Value-1500000.06200000.0
Percentage of ImpairmentsOnFixedMaturitiesCreditRelatedLosses100.0100.0

thg:ImpairmentsOnFixedMaturitiesIncludedInIntendToSell

thg:ImpairmentsOnFixedMaturitiesIncludedInIntendToSell


Impairments
Period End2020-12-312020-03-31
Value0.016
Percentage of ImpairmentsOnFixedMaturitiesIncludedInIntendToSell0.0100.0

thg:IncomeLossFromContinuingOperationsExcludingNonoperatingItemsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

thg:IncomeLossFromContinuingOperationsExcludingNonoperatingItemsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30
Value128761411187910710111697100811011181041231.010657-34.211779105108107104841167085
Percentage of IncomeLossFromContinuingOperationsExcludingNonoperatingItemsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementBeforeTax


Other
Period End2021-06-302020-12-312020-09-302020-06-302020-03-31
Value0.20.00.20.116
Percentage of OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementBeforeTax100.00.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementNetOfTax


Other
Period End2021-06-302020-12-312020-09-302020-06-302020-03-31
Value0.20.00.10.112
Percentage of OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementNetOfTax100.00.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementTax

thg:OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementTax


Other
Period End2020-12-312020-09-302020-06-302020-03-31
Value0100000.003400000.0
Percentage of OtherComprehensiveIncomeLossAdditionalImpairmentLossesRecognizedInConsolidatedIncomeStatementTax0.0100.00.0100.0

thg:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAociPensionAndOtherPostretirementBenefitPlansForNetActuarialGainLoss

thg:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAociPensionAndOtherPostretirementBenefitPlansForNetActuarialGainLoss


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value700000.0700000.01100000.01200000.01200000.02300000.02200000.02300000.0
Percentage of OtherComprehensiveIncomeLossAmortizationAdjustmentFromAociPensionAndOtherPostretirementBenefitPlansForNetActuarialGainLoss100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAociPensionAndOtherPostretirementBenefitPlansForNetActuarialGainLossAndNetPriorServiceCostCreditNetOfTax us-gaap:StatementEquityComponents

thg:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAociPensionAndOtherPostretirementBenefitPlansForNetActuarialGainLossAndNetPriorServiceCostCreditNetOfTax

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312015-03-312014-03-31
Value700000.0700000.01200000.01100000.01200000.01200000.02200000.02300000.02200000.02300000.07200000.01900000.0900000.0-2300000.02400000.02300000.02400000.02300000.01700000.01800000.0
Percentage of OtherComprehensiveIncomeLossAmortizationAdjustmentFromAociPensionAndOtherPostretirementBenefitPlansForNetActuarialGainLossAndNetPriorServiceCostCreditNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostBeforeTax

thg:OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostBeforeTax


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value900000.0800000.01400000.01500000.01500000.02800000.02800000.02900000.0
Percentage of OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostNetOfTax

thg:OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostNetOfTax


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value700000.0700000.01100000.01200000.01200000.02300000.02200000.02300000.0
Percentage of OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostTax

thg:OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostTax


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value200000.0100000.0300000.0300000.0300000.0500000.0600000.0600000.0
Percentage of OtherComprehensiveIncomeLossAmortizationOfNetActuarialGainsLossesRecognizedAsNetPeriodicBenefitCostTax100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesHavingCreditLossesRecognizedInTheConsolidatedStatementsOfIncome

thg:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesHavingCreditLossesRecognizedInTheConsolidatedStatementsOfIncome


Other
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value200000.03600000.0300000.010000000.0-12400000.0200000.0700000.0500000.0
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesHavingCreditLossesRecognizedInTheConsolidatedStatementsOfIncome100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesHavingNoCreditLossesRecognizedInTheConsolidatedStatementsOfIncome

thg:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesHavingNoCreditLossesRecognizedInTheConsolidatedStatementsOfIncome


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value61-185.51227241-70.8-19.5999999999999742101
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesHavingNoCreditLossesRecognizedInTheConsolidatedStatementsOfIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementBeforeTax


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value4000000.02200000.01400000.0-6400000.03300000.0-800000.0-400000.0
Percentage of OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementBeforeTax100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementNetOfTax


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value3200000.01600000.01100000.0-5000000.02600000.0-600000.0-300000.0
Percentage of OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementNetOfTax100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementTax

thg:OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementTax


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value-200000.0-600000.0-300000.01400000.0100000.0200000.0100000.0
Percentage of OtherComprehensiveIncomeLossCreditRecoveriesLossesRecognizedInConsolidatedIncomeStatementTax100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementBeforeTax


Other
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-30
Value2342309-15.558133
Percentage of OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementBeforeTax100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementNetOfTax


Other
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-30
Value1833244-12.246105
Percentage of OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementNetOfTax100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementTax


Other
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-30
Value4.98.765-3.31227
Percentage of OtherComprehensiveIncomeLossNetUnrealizedGainArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementTax100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementBeforeTax


Other
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value0.36.23.014-22.1-0.60.10.2
Percentage of OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementNetOfTax


Other
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value0.25.12.111-17.4-0.60.10.2
Percentage of OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementTax

thg:OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementTax


Other
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value100000.01100000.0900000.02900000.0-4700000.000
Percentage of OtherComprehensiveIncomeLossNetUnrealizedGainLossesArisingDuringPeriodHavingCreditLossesInConsolidatedIncomeStatementTax100.0100.0100.0100.0100.00.00.0

thg:OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementBeforeTax

thg:OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementBeforeTax


Other
Period End2021-06-302021-03-312020-06-302020-03-31
Value-84.3234-309.7100
Percentage of OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementBeforeTax100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementNetOfTax

thg:OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementNetOfTax


Other
Period End2021-06-302021-03-312020-06-302020-03-31
Value-66.5184-244.779
Percentage of OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementNetOfTax100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementTax

thg:OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementTax


Other
Period End2021-06-302021-03-312020-06-302020-03-31
Value17-49.265-20.9
Percentage of OtherComprehensiveIncomeLossNetUnrealizedLossesArisingDuringPeriodHavingNoCreditLossesInConsolidatedIncomeStatementTax100.0100.0100.0100.0

thg:OtherComprehensiveIncomeLossPercentageOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncomeForPensionAndPostRetirementBenefitsAllocatedToLossAdjustmentExpenses us-gaap:StatementEquityComponents

thg:OtherComprehensiveIncomeLossPercentageOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncomeForPensionAndPostRetirementBenefitsAllocatedToLossAdjustmentExpenses

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-03-312014-09-302014-03-312013-12-312013-09-30
Value40.040.0040.00.40.400.40.40.400.40.40.400.40.40.400.40.40.40.400.4
Percentage of OtherComprehensiveIncomeLossPercentageOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncomeForPensionAndPostRetirementBenefitsAllocatedToLossAdjustmentExpenses100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.00.0100.0

thg:OtherComprehensiveIncomeLossPercentageOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncomeForPensionAndPostRetirementBenefitsAllocatedToOtherOperatingExpenses us-gaap:StatementEquityComponents

thg:OtherComprehensiveIncomeLossPercentageOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncomeForPensionAndPostRetirementBenefitsAllocatedToOtherOperatingExpenses

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-03-312014-09-302014-03-312013-12-312013-09-30
Value60.060.0060.00.60.600.60.60.600.60.60.600.60.60.600.60.60.60.600.6
Percentage of OtherComprehensiveIncomeLossPercentageOfAmountsReclassifiedFromAccumulatedOtherComprehensiveIncomeForPensionAndPostRetirementBenefitsAllocatedToOtherOperatingExpenses100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.00.0100.0

thg:PaymentsOfExtraordinaryDividends us-gaap:StatutoryAccountingPracticesByJurisdiction

thg:PaymentsOfExtraordinaryDividends

stpr:MI


Payments
Period End2020-12-31
Value82
Percentage of PaymentsOfExtraordinaryDividends100.0

thg:PaymentsToAcquireEquitySecuritiesAndOtherInvestments

thg:PaymentsToAcquireEquitySecuritiesAndOtherInvestments


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value30539521281091687253375035533982
Percentage of PaymentsToAcquireEquitySecuritiesAndOtherInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:PerShareEffectOfDilutiveSecuritiesOnIncomeFromContinuingOperations

thg:PerShareEffectOfDilutiveSecuritiesOnIncomeFromContinuingOperations


Per
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302018-12-312018-09-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-03-312011-03-312010-12-312010-09-30
Value0.050.030.060.030.020.050.040.0300.040.020.010.020.01-0.080.01-0.010.03-0.250.030.050.02-0.20.030.030.03110000.00.030.020.02-0.02-0.01-0.02-0.02
Percentage of PerShareEffectOfDilutiveSecuritiesOnIncomeFromContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:PerShareEffectOfDilutiveSecuritiesOnNetIncome

thg:PerShareEffectOfDilutiveSecuritiesOnNetIncome


Per
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302018-12-312018-09-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312010-12-312010-09-30
Value0.060.040.040.020.020.050.040.030.2-0.030.0200.020.01-0.090.010.010.02-0.260.040.050.02-0.220.030.040.02110000.00.030.020.03-0.02-0.01
Percentage of PerShareEffectOfDilutiveSecuritiesOnNetIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:ProceedsFromSaleOfEquitySecuritiesAndOtherInvestments

thg:ProceedsFromSaleOfEquitySecuritiesAndOtherInvestments


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value9866191763731841620288126292126
Percentage of ProceedsFromSaleOfEquitySecuritiesAndOtherInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:ShareRepurchaseProgramPercentageOfSharesRepurchased us-gaap:ShareRepurchaseProgram

thg:ShareRepurchaseProgramPercentageOfSharesRepurchased

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreement


Share
Period End2020-10-29
Value80.0
Percentage of ShareRepurchaseProgramPercentageOfSharesRepurchased100.0

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreements


Share
Period End2020-10-29
Value80.0
Percentage of ShareRepurchaseProgramPercentageOfSharesRepurchased100.0

us-gaap:AcceleratedShareRepurchaseProgramAdjustment us-gaap:StatementEquityComponents

us-gaap:AcceleratedShareRepurchaseProgramAdjustment

us-gaap:AdditionalPaidInCapital


Accelerated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value9.46.6-29.84.95.024-14.73.911-50.1
Percentage of AcceleratedShareRepurchaseProgramAdjustment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AllocatedShareBasedCompensationExpenseNetOfTax

us-gaap:AllocatedShareBasedCompensationExpenseNetOfTax


Allocated
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value4.34.43.93.63.93.33.53.33.23.62.42.72.72.11.91.81.81.22.82.12.52.42.32.11.42.32.31.42.72.31.72.22.01.8
Percentage of AllocatedShareBasedCompensationExpenseNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CurrentIncomeTaxExpenseBenefit

us-gaap:CurrentIncomeTaxExpenseBenefit


Current
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value288.9362918212522201219161720117.34.9334.28.06.5339.1115.72920-1.1-1.69.22.72.4-0.54.07.2-16.9-10.93940-18.4-26.4
Percentage of CurrentIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleRealizedGain us-gaap:InvestmentType

us-gaap:DebtSecuritiesAvailableForSaleRealizedGain

thg:FixedMaturitiesExcludingHeldForSale


Debt
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value3.42.32.72.71.61.61.00.10.81.00.21.72.4
Percentage of DebtSecuritiesAvailableForSaleRealizedGain100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:FixedMaturitiesIncludingHeldForSale


Debt
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1.02.93.42.32.72.71.61.61.00.51.01.70.64.03.0
Percentage of DebtSecuritiesAvailableForSaleRealizedGain0.00.0100.0100.0100.0100.0100.0100.0100.0500.0125.0170.0300.0235.3125.0

us-gaap:DebtSecuritiesAvailableForSaleRealizedLoss us-gaap:InvestmentType

us-gaap:DebtSecuritiesAvailableForSaleRealizedLoss

thg:FixedMaturitiesExcludingHeldForSale


Debt
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.22.30.40.72.41.11.53.11.52.11.76.10.3
Percentage of DebtSecuritiesAvailableForSaleRealizedLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:FixedMaturitiesIncludingHeldForSale


Debt
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.27.20.22.30.40.72.41.11.53.71.62.52.36.30.5
Percentage of DebtSecuritiesAvailableForSaleRealizedLoss0.00.0100.0100.0100.0100.0100.0100.0100.0119.4106.7119.0135.3103.3166.7

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-800000.0-800000.0-1400000.0-1500000.0-1400000.0-1500000.0-2800000.0-2800000.0-2900000.0-2800000.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value4.64.65.55.65.55.65.95.85.95.8
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanInterestCost

us-gaap:DefinedBenefitPlanInterestCost


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value3.73.74.64.54.64.65.45.35.35.3
Percentage of DefinedBenefitPlanInterestCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-0.1-0.10.50.40.50.52.32.32.32.3
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DepreciationAndAmortization

us-gaap:DepreciationAndAmortization


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value4.39999999999999953.84.34.44.45.14.84.85.16.93.66.97.26.97.17.67.87.66.18.47.88.47.46.08.78.18.28.47.89.19.68.09.08.49.68.48.59.1144.73.44.24.74.23.74.1
Percentage of DepreciationAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCash us-gaap:StatementEquityComponents

us-gaap:DividendsCash

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2525252425251222324242182323222321212121191919191818181816161616141414141313131312121211111212
Percentage of DividendsCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense

us-gaap:EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense


Employee
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value1100000.01200000.01200000.01000000.0900000.01100000.01100000.0800000.0900000.0900000.0900000.0800000.01000000.0600000.0300000.01500000.01400000.01100000.01200000.01100000.0900000.01000000.01000000.0700000.01400000.01200000.01400000.01300000.01400000.01200000.01200000.01100000.0700000.01300000.01100000.01200000.0800000.01400000.01000000.01200000.0900000.01200000.0900000.01100000.0900000.0
Percentage of EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquitySecuritiesFvNiGainLoss

us-gaap:EquitySecuritiesFvNiGainLoss


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2639573061-136.231151148-50.1236.0-22.9
Percentage of EquitySecuritiesFvNiGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquitySecuritiesFvNiRealizedGainLoss

us-gaap:EquitySecuritiesFvNiRealizedGainLoss


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-100000.0600000.0100000.0-3500000.0-15800000.0-600000.01800000.0-200000.0100000.01100000.0-2900000.0-200000.0-1300000.0500000.0
Percentage of EquitySecuritiesFvNiRealizedGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquitySecuritiesFvNiUnrealizedGainLoss

us-gaap:EquitySecuritiesFvNiUnrealizedGainLoss


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2638573377-135.629151147-47.2237.3-23.4
Percentage of EquitySecuritiesFvNiUnrealizedGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss

us-gaap:FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value0-400000.0700000.0300000.0200000.0-300000.0
Percentage of FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss0.0100.0100.0100.0100.0100.0

us-gaap:FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss us-gaap:InvestmentType

us-gaap:CommercialMortgageBackedSecurities


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value0-400000.0600000.0300000.0200000.0-400000.0
Percentage of FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss0.0100.085.7100.0100.0133.3

us-gaap:DebtSecurities


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value0-400000.0700000.0300000.0200000.0-300000.0
Percentage of FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss0.0100.0100.0100.0100.0100.0

us-gaap:MunicipalBonds


Fair
Period End2020-12-312020-09-302020-06-302020-03-31
Value100000.00100000.0100000.0
Percentage of FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss14.30.050.0-33.3

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value0100000.03500000.0200000.0200000.0-100000.0100000.000100000.000300000.0000-100000.0100000.0100000.000-1100000.000-400000.00-100000.0300000.0200000.01700000.0-100000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.0100.0100.0100.0100.0100.0100.00.00.0100.00.00.0100.00.00.00.0100.0100.0100.00.00.0100.00.00.0100.00.0100.0100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 us-gaap:FairValueByAssetClass

thg:EquitySecuritiesAndOther


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-30
Value0100000.03500000.0200000.0200000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.0100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value0-400000.0600000.0300000.0200000.0-300000.0-200000.0300000.0900000.0400000.0600000.0-200000.0-200000.0-700000.0-1400000.0200000.0100000.0200000.0-1100000.0-200000.01500000.01500000.0-1200000.0200000.0-2200000.0-700000.0-400000.0700000.0-700000.0-800000.0-6100000.0-2800000.0-1500000.0-1000000.0-500000.0800000.04300000.0700000.0100000.02100000.01000000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss us-gaap:InvestmentType

us-gaap:CommercialMortgageBackedSecurities


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-09-302017-06-302016-12-312016-09-302016-06-30
Value0-400000.0600000.0300000.0200000.0-400000.0-200000.0200000.0300000.0200000.0200000.0-200000.0-100000.0-200000.00100000.0-800000.0-100000.0200000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.0100.0100.0100.0100.0133.3100.066.733.350.033.3100.050.028.60.0100.072.750.013.3

us-gaap:DebtSecurities


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value0-400000.0600000.0300000.0200000.0-300000.0-200000.0300000.0900000.0400000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MunicipalBonds


Fair
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value000100000.00100000.0600000.0200000.0400000.00-100000.0-500000.0-800000.0200000.0200000.0200000.0-900000.0-100000.0600000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.00.00.0-33.3-0.033.366.750.066.7-0.050.071.457.1100.0200.0100.081.850.040.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value0.81.10.40.30.71.40.70.68.21.50.60.60.91.70.60.64.01.10.91.61.41.51.80.92.51.4381.10.92.28.31.41.06.01.80.91.66.33.013
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales us-gaap:InvestmentType

us-gaap:CommercialMortgageBackedSecurities


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.10.20.10.20.20.50.10.20.10.50.10.10.10.50.10.20.10.40.40.40.3
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales12.518.225.066.728.635.714.333.31.233.316.716.711.129.416.733.32.536.444.425.021.4

us-gaap:CorporateDebtSecurities


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.00.10.00.00.00.10.10.00.00.1-0.10.10.00.10.00.13.00.30.10.00.1
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales0.09.10.00.00.07.114.30.00.06.7-16.716.70.05.90.016.775.027.311.10.07.1

us-gaap:DebtSecurities


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.81.10.40.30.71.40.70.68.21.5
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MunicipalBonds


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.70.80.30.10.50.80.50.48.10.90.60.40.81.10.50.30.90.40.40.80.9
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales87.572.775.033.371.457.171.466.798.860.0100.066.788.964.783.350.022.536.444.450.064.3

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3


Fair
Period End2020-12-312020-09-302020-06-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-12-312015-09-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value0.00.03.50.00.50.00.00.02.30.00.00.01.20.04.6-32.10.02.6370.00.02.22.40.20.03.17.79.39.3
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel30.00.0100.00.0100.00.00.00.0100.00.00.00.0100.00.0100.0100.00.0100.0100.00.00.0100.0100.0100.00.0100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 us-gaap:InvestmentType

us-gaap:DebtSecurities


Fair
Period End2020-12-312020-09-302020-06-30
Value0.00.03.5
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel30.00.0100.0

us-gaap:MunicipalBonds


Fair
Period End2020-12-312020-09-302020-06-302018-12-312018-09-302017-12-312017-09-302016-12-312016-09-30
Value0.00.03.50.00.50.01.90.01.2
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel30.00.0100.00.0100.00.082.60.0100.0

us-gaap:FederalIncomeTaxExpenseBenefitContinuingOperations

us-gaap:FederalIncomeTaxExpenseBenefitContinuingOperations


Federal
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value302129-2.61519242618111415321225-18.92224231314149.9244.413-0.6-8.112168.29.6
Percentage of FederalIncomeTaxExpenseBenefitContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnRepurchaseOfDebtInstrument

us-gaap:GainLossOnRepurchaseOfDebtInstrument


Gain
Period End2020-12-312020-09-302016-12-312016-09-302016-06-302015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value0-6100000.0-2200000.00-86100000.00-5600000.0-1800000.0-16700000.00-8600000.0
Percentage of GainLossOnRepurchaseOfDebtInstrument0.0100.0100.00.0100.00.0100.0100.0100.00.0100.0

us-gaap:ImpairmentOfInvestments

us-gaap:ImpairmentOfInvestments


Impairment
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value0.2-1.60.8-1.4282.60.80.02.00.71.90.91.01.52.0
Percentage of ImpairmentOfInvestments100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ImpairmentOfInvestments us-gaap:InvestmentType

us-gaap:FixedMaturities


Impairment
Period End2021-06-302020-09-302020-06-302020-03-312019-09-302019-06-302018-09-30
Value0.2-1.71.4222.10.70.7
Percentage of ImpairmentOfInvestments100.0-212.5-100.077.9262.50.0100.0

us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTax us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTax

thg:Life


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-302018-03-31
Value-1.1-0.1-1.7-0.6-0.1-1.3-1.8-0.8-0.9-0.80.1-0.1
Percentage of IncomeLossFromDiscontinuedOperationsNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTax us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

thg:Life, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Income
Period End2020-09-302020-06-302020-03-31
Value0.10.0-0.4
Percentage of IncomeLossFromDiscontinuedOperationsNetOfTax-16.7-0.030.8

us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare

thg:Life


Income
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-0.02-0.05-0.02-0.01-0.03-0.05-0.02-0.02-0.02
Percentage of IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare

thg:Life


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-30
Value-0.03-0.01-0.03-0.010-0.03-0.05-0.02-0.02-0.020.01
Percentage of IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value24-143.6765251-112.766257.2-88.054126.7-69.1532033-107.438642.8-98.94.1552.6-62.96845-25.3-76.5398.6-10.0-101.411122-17.7-28.2-14.57453-64.5194229-177.1
Percentage of IncreaseDecreaseInAccountsPayableAndAccruedLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-1.9-12.6-4.91.1-9.9361.4-1.31.2-13.829-9.8-3.47.4-42.910-27.72023-28.1152.9-12.8-21.5-25.97.1-12.2-21.5-26.7-8.2-20.8-22.3-13.4-18.457-29.0-11.81823-9.30.7-5.6-3.9-0.5-2.2-45.4
Percentage of IncreaseDecreaseInDeferredIncomeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredPolicyAcquisitionCosts

us-gaap:IncreaseDecreaseInDeferredPolicyAcquisitionCosts


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1313-4.920-3.9-1.7-7.7177.0-2.7-8.813103.9-13.215218.4-20.0148.94.6-28.50.2137.6-14.7-0.32014-15.912155.2-11.85.3279.4-1.1-20.08.9-5.4-0.8162219
Percentage of IncreaseDecreaseInDeferredPolicyAcquisitionCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInInsuranceLiabilities

us-gaap:IncreaseDecreaseInInsuranceLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value15627025238997562204132991112241211273253214723715180137195-202.8-5.4107222-158.862191160-80.665105-24.3176111192138-160.19713125128614643
Percentage of IncreaseDecreaseInInsuranceLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInPremiumsReceivable

us-gaap:IncreaseDecreaseInPremiumsReceivable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value26215.351215.5-39.070434.3-60.333106-6.2-66.92280-6.8-56.53689-41.0-62.1158513372410517-48.540116-0.3-34.2-3.8140-49.3-28.3-31.35.7-15.5-37.0739968
Percentage of IncreaseDecreaseInPremiumsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInReinsuranceRecoverable

us-gaap:IncreaseDecreaseInReinsuranceRecoverable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value498.53227-6.66.48032382815935-33.18676264-36.7109-67.144-47.1105-96.0-68.210585-166.4-19.42445-64.9-38.6-25.7-19.636102.616733299.814231132-28.7
Percentage of IncreaseDecreaseInReinsuranceRecoverable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

thg:NonVestedStockGrants


Incremental
Period End2021-06-302021-03-312020-09-302020-06-302019-09-30
Value200000.0200000.0200000.0200000.0300000.0
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.0100.0100.0100.0100.0

us-gaap:EmployeeStockOption


Incremental
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value400000.0300000.00100000.0100000.00300000.0300000.0300000.00300000.0300000.0300000.0100000.0300000.0200000.0200000.0-100000.0200000.0300000.0
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements200.0150.00.050.050.00.0100.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:InsuranceServicesRevenue

us-gaap:InsuranceServicesRevenue


Insurance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1262124512311212116012171223119911861171115711431129111410911072
Percentage of InsuranceServicesRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InsuranceServicesRevenue us-gaap:StatementBusinessSegments

thg:CommercialLinesSegment


Insurance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value758748733713698724729710705698693687681676660648
Percentage of InsuranceServicesRevenue60.060.159.658.860.259.559.659.259.459.759.960.160.360.760.560.4

thg:PersonalLinesSegment


Insurance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value500493493493456488488483474465459452444434428421
Percentage of InsuranceServicesRevenue39.639.640.040.739.340.139.940.340.039.739.739.639.339.039.239.3

us-gaap:AllOtherSegments


Insurance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value3.94.24.65.55.44.65.66.36.77.44.03.83.5
Percentage of InsuranceServicesRevenue0.30.30.40.50.50.40.50.50.60.60.30.30.3

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value353178484394294174426392321175383343317187442360324167367336280157
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value30443516624030448425726531945926753406537283331347452278298346443
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value745781695709712728742705717699706449783785759878725766843692729699
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value80-232.52338321-102.8-19.05813215260-28.9-58.2-299.5-28.89.23534-198.14.8124156-67.7-48.7-140.74517-68.66079-28.6-8.9-203.916-20.7862968277.039
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value62-185.51527251-83.2-19.34310111646-25.2-49.1-205.1-23.13.71919-135.4-2.07796-48.0-35.1-94.7267.2-48.73448-24.7-9.3-138.25.5-23.3514440311637
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value62-185.51527251-83.2-19.44310111627-25.2-49.1-123.5-23.13.71919-135.4-2.07796-48.0-35.1-94.7267.2-48.73448-25.2-9.5-137.45.4-23.3514443
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.5100.0100.0100.059.2100.0100.060.2100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0102.0102.299.498.2100.0100.0100.2107.3

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value17-47.07.21070-19.60.315313513-3.7-9.194-5.75.515-15.1165-6.8-47.6-59.5-101.71346-18.6-10.419-26.6-30.21120.6-66.511-2.6-34.815243.79.7-2.3
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeTax

us-gaap:OtherComprehensiveIncomeLossBeforeTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value80-231.72839323-101.34.46113615596-24.5-57.7-303.0-7.2143245-239.04.4126157-71.0-50.0-128.335-4.2-75.36881-7.12.7-197.74.2-44.01001884
Percentage of OtherComprehensiveIncomeLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value4.8-1.64.64.90.93.13.90.60.8-0.30.20.0-0.24.3157.24.1-67.23.44.522-71.95.91412244.6224.3133.9158.8185.93.2
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value4.80.66.06.33.34.37.43.74.03.6-1.02.63.32.36.3127.95.8-78.57.37.019-69.37.31210197.0198.4126.01411158.04.3
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value0-2200000.0-1400000.0-1400000.0-2400000.0-1200000.0-3500000.0-3100000.0-3200000.0-3900000.0-1500000.0-2400000.0-3300000.02500000.0-2000000.03000000.0-700000.01700000.04700000.03900000.02500000.0-3100000.01200000.01400000.0-1900000.0-1400000.0-4200000.02400000.0-2600000.04100000.0-1200000.02100000.0-200000.02300000.0-2600000.02100000.01100000.0
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossTax

us-gaap:OtherComprehensiveIncomeLossTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value18-46.98.41070-19.35.316323621-2.8-9.075-0.87.314-19.0155-6.8-48.0-60.1-101.31441-15.2-3.522-29.2-31.11024.6-64.36.9-95.239-19.330
Percentage of OtherComprehensiveIncomeLossTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherCostAndExpenseOperating

us-gaap:OtherCostAndExpenseOperating


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value13513914713712213513813613113212913115816415715115315716615414314616415816017218315816315118215917415016114513514511513310491138919292
Percentage of OtherCostAndExpenseOperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherOperatingIncomeExpenseNet us-gaap:StatementBusinessSegments

us-gaap:OtherOperatingIncomeExpenseNet

thg:CommercialLinesSegment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-0.4-0.30.7-0.8-3.9-2.20.4-0.4-0.7-0.8-0.1-0.7-0.5-0.20.2-0.2-0.4-0.2
Percentage of OtherOperatingIncomeExpenseNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:PersonalLinesSegment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.90.82.01.7-1.30.51.41.81.11.42.21.21.21.31.71.11.01.2
Percentage of OtherOperatingIncomeExpenseNet-225.0-266.7285.7-212.533.3-22.7350.0-450.0-157.1-175.0-2200.0-171.4-240.0-650.0850.0-550.0-250.0-600.0

us-gaap:AllOtherSegments


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-1.8-1.5-6.6-1.5-1.9-2.0-2.7-2.7-2.7-3.1
Percentage of OtherOperatingIncomeExpenseNet450.0500.0-942.9187.548.790.9-675.0675.0385.7387.5

us-gaap:OtherThanTemporaryImpairmentLossDebtSecuritiesAvailableForSaleRecognizedInEarnings us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:OtherThanTemporaryImpairmentLossDebtSecuritiesAvailableForSaleRecognizedInEarnings

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Other
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.2-1.5-1.7-1.4220.80.80.40.90.40.70.60.31.3
Percentage of OtherThanTemporaryImpairmentLossDebtSecuritiesAvailableForSaleRecognizedInEarnings100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForLossesAndLossAdjustmentExpense

us-gaap:PaymentsForLossesAndLossAdjustmentExpense


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value657613650635598659683657641634650396724724725691671619646635627601
Percentage of PaymentsForLossesAndLossAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value440617406632413376306590208483152451404418348628380288577672397373415707293375610516249333607487379223569446491663565575242304419462263256
Percentage of PaymentsToAcquireAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value-800000.0-6700000.0-900000.0-600000.0-1200000.0-5800000.0-1100000.0-1100000.0-1400000.0-4200000.000-1000000.0-2200000.0-1100000.0-200000.0-100000.0-2700000.0-4300000.0-500000.0-6300000.0-3000000.0-7500000.0-1400000.0-400000.0-1900000.0-1100000.0-200000.0-800000.0-1500000.0-1300000.0-500000.0-2300000.0-1000000.0-200000.0100000.0-100000.0-200000.0100000.000-600000.0400000.0-200000.0-100000.0
Percentage of ProceedsFromPaymentsForOtherFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities

us-gaap:ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value291528356317327316486360297193223233342295405
Percentage of ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt us-gaap:InvestmentType

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt

thg:FixedMaturitiesExcludingHeldForSale


Proceeds
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value37916623186162607183845712947
Percentage of ProceedsFromSaleOfAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:FixedMaturitiesIncludingHeldForSale


Proceeds
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value34217379166231861626017510516412717292
Percentage of ProceedsFromSaleOfAvailableForSaleSecuritiesDebt0.00.0100.0100.0100.0100.0100.0100.0100.5246.1125.5195.5223.8132.5197.0

us-gaap:ProceedsFromStockOptionsExercised

us-gaap:ProceedsFromStockOptionsExercised


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value8.35.81.50.31.53.02.01.95.55.02.11.64.86.33.98.91.78.61.43.54.86.52.35.02.17.24.31.62.93.83.36.6104.50.70.60.21.10.00.00.03.92.76.42.10.8
Percentage of ProceedsFromStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue

thg:PerformanceBasedAndMarketBasedRestrictedStockUnits


Share
Period End2020-12-312020-09-302019-12-312018-12-312018-09-302018-06-302018-03-31
Value0007.880081.91
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue0.00.00.0100.00.00.0100.0

thg:TimeBasedRestrictedStockUnits


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312012-09-302011-09-30
Value0.19116.82-0.2603.76112.241.233.094.5797.142.841.312.4287.470.32-0.35
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue0.00.00.00.00.00.00.00.00.00.036.00.00.0106.80.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue

thg:PerformanceBasedAndMarketBasedRestrictedStockUnits


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0114.66000105.1-0.420-0.59117.6800.950.83116.82
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue0.0100.00.00.00.0100.0100.00.0100.0100.00.0100.0100.0100.0

thg:TimeBasedRestrictedStockUnits


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312012-09-302011-09-30
Value0.28115.0400-0.88118.6-0.110.160.04117.51-0.010.460.61110.60-3.25
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue0.0100.30.00.00.0112.826.20.0-6.899.90.048.473.594.70.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue

thg:PerformanceBasedAndMarketBasedRestrictedStockUnits


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0122.27000.6680.26-4.8201.6582.7400070.24
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue0.0100.00.00.0100.0100.0100.00.0100.0100.00.00.00.0100.0

thg:TimeBasedRestrictedStockUnits


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312012-09-302011-09-30
Value0.13110.681.930.636.5485.440.40.30.6283.250.070.062.3270.240.36-0.06
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue0.090.50.00.0990.9106.5-8.30.037.6100.60.00.00.0100.00.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice


Share
Period End2020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value00.5306.145.8195.3900.61088.48
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice0.0100.00.0100.0100.0100.00.0100.00.0100.0

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value1.4780.96-0.82-1.18-1.5479.40.8-2.39-3.1975.98-1.53-0.81.4370.315.83-2.21-0.2159.710.190.23-2.5651.13-1.191.370.543.790.340.33-0.2538.910.90.962.5830.26-3.86-1.16-1.7532.24-0.310
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value0115.3500-0.2118.5424.310095.0500.30.1110.5800-0.3391.18-0.570082.7400.060.0370.250.030.010.0357.9900.020.0242.490.030036.8100
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice0.0100.00.00.0100.0100.0100.00.00.0100.00.0100.0100.0100.00.00.0100.0100.0100.00.00.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.00.00.0100.00.00.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation

us-gaap:TreasuryStock


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value5.36.21.00.41.43.31.21.54.05.73.91.34.96.63.07.32.79.93.43.57.2105.33.96.6167.03.18.0126.17.014172.61.51.87.51.70.40.8154.810.04.27.3
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense


Supplemental
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value772789701721723730750705725712707422799803773898742773714700726718
Percentage of SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense


Supplemental
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-27.6-8.2-6.5-12.2-13.9-2.0-8.10.3-20.6-13.2-1.827-16.2-17.9-13.8-20.1-17.1-7.4-174.1-8.83.7-18.7
Percentage of SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TreasuryStockValueAcquiredCostMethod us-gaap:StatementEquityComponents

us-gaap:TreasuryStockValueAcquiredCostMethod

us-gaap:TreasuryStock


Treasury
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-312010-12-31
Value7350984514591590.0155200131811130.09.2234.60.43719484261158.50.0130.46.30.05.947250.010.01.70.0
Percentage of TreasuryStockValueAcquiredCostMethod100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.00.0

us-gaap:UnderwritingIncomeLoss us-gaap:StatementBusinessSegments

us-gaap:UnderwritingIncomeLoss

thg:CommercialLinesSegment


Underwriting
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value53-49.355182110253029361020371627-13.92.3-2.7
Percentage of UnderwritingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:PersonalLinesSegment


Underwriting
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value9.558284317441328105.715288.014224029-8.4
Percentage of UnderwritingIncomeLoss17.7-119.550.8229.981.7424.054.294.737.515.5147.1138.521.289.682.5-292.81282.6311.1

us-gaap:AllOtherSegments


Underwriting
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value-0.3-0.3-0.3-0.3-0.4-3.3-0.3-0.4-0.3-0.3-1.1-1.0-1.1
Percentage of UnderwritingIncomeLoss-0.60.6-0.5-1.6-1.9-31.7-1.2-1.3-1.0-0.8-10.6-4.8-2.9

thg:AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses

thg:AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value7198708969456984662764876452
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses100.0100.0100.0100.0100.0100.0100.0

thg:AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses us-gaap:InvestmentType

thg:FixedMaturitiesIncludingHeldForSale


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value719870896945698466276487
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses100.0100.0100.0100.0100.0100.0

us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivables


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value756771726566
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses1.10.91.01.01.01.0

us-gaap:CommercialMortgageBackedSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value739722705695659661
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses10.310.210.210.09.910.2

us-gaap:CorporateDebtSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value396539083769380737713742
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses55.155.154.354.556.957.7

us-gaap:ForeignGovernmentDebtSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value2.22.22.24.24.24.2
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses0.00.00.00.10.10.1

us-gaap:MunicipalBonds


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value1053104610421033918833
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses14.614.815.014.813.912.9

us-gaap:ResidentialMortgageBackedSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value9809819781017922913
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses13.613.814.114.613.914.1

us-gaap:USTreasuryAndGovernment


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value381360376353286265
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasisNetOfAllowanceForCreditLosses5.35.15.45.14.34.1

thg:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCostNetOfAllowanceForCreditLosses


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value2491246123062279
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCostNetOfAllowanceForCreditLosses100.0100.0100.0100.0

thg:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCostNetOfAllowanceForCreditLosses


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value1907182017741844
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCostNetOfAllowanceForCreditLosses100.0100.0100.0100.0

thg:AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCostNetOfAllowanceForCreditLosses


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value735762775727
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCostNetOfAllowanceForCreditLosses100.0100.0100.0100.0

thg:AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostNetOfAllowanceForCreditLosses


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value5403531751905198
Percentage of AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostNetOfAllowanceForCreditLosses100.0100.0100.0100.0

thg:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCostNetOfAllowanceForCreditLosses


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value268273334346
Percentage of AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCostNetOfAllowanceForCreditLosses100.0100.0100.0100.0

thg:AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCostNetOfAllowanceForCreditLosses

thg:AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCostNetOfAllowanceForCreditLosses


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value1795177117551786
Percentage of AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCostNetOfAllowanceForCreditLosses100.0100.0100.0100.0

thg:AvailableForSaleSecuritiesDebtMaturitiesYearFiveAmortizedCostBasis us-gaap:InvestmentType

thg:AvailableForSaleSecuritiesDebtMaturitiesYearFiveAmortizedCostBasis

us-gaap:Mortgages


Available
Period End2020-12-31
Value77
Percentage of AvailableForSaleSecuritiesDebtMaturitiesYearFiveAmortizedCostBasis100.0

thg:AvailableForSaleSecuritiesDebtMaturitiesYearFourAmortizedCostBasis us-gaap:InvestmentType

thg:AvailableForSaleSecuritiesDebtMaturitiesYearFourAmortizedCostBasis

us-gaap:Mortgages


Available
Period End2020-12-31
Value16
Percentage of AvailableForSaleSecuritiesDebtMaturitiesYearFourAmortizedCostBasis100.0

thg:AvailableForSaleSecuritiesDebtMaturitiesYearThreeAmortizedCostBasis us-gaap:InvestmentType

thg:AvailableForSaleSecuritiesDebtMaturitiesYearThreeAmortizedCostBasis

us-gaap:Mortgages


Available
Period End2020-12-31
Value27
Percentage of AvailableForSaleSecuritiesDebtMaturitiesYearThreeAmortizedCostBasis100.0

thg:AvailableForSaleSecuritiesDebtMaturitiesYearTwoAmortizedCostBasis us-gaap:InvestmentType

thg:AvailableForSaleSecuritiesDebtMaturitiesYearTwoAmortizedCostBasis

us-gaap:Mortgages


Available
Period End2020-12-31
Value57
Percentage of AvailableForSaleSecuritiesDebtMaturitiesYearTwoAmortizedCostBasis100.0

thg:AvailableForSaleSecuritiesDebtSecuritiesIncludingHeldForSaleFairValue

thg:AvailableForSaleSecuritiesDebtSecuritiesIncludingHeldForSaleFairValue


Available
Period End2020-09-30
Value7473
Percentage of AvailableForSaleSecuritiesDebtSecuritiesIncludingHeldForSaleFairValue100.0

thg:DebtLongTermAndShortTermCombinedAmountGross

thg:DebtLongTermAndShortTermCombinedAmountGross


Debt
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-31
Value786786661716662677787
Percentage of DebtLongTermAndShortTermCombinedAmountGross100.0100.0100.0100.0100.0100.0100.0

thg:DefinedBenefitPlanPensionPlansWithPlanAssetsInExcessOfAccumulatedBenefitObligations

thg:DefinedBenefitPlanPensionPlansWithPlanAssetsInExcessOfAccumulatedBenefitObligations


Defined
Period End2020-12-31
Value27
Percentage of DefinedBenefitPlanPensionPlansWithPlanAssetsInExcessOfAccumulatedBenefitObligations100.0

thg:ExtraordinaryDividendsPayableCurrentAndNoncurrent us-gaap:StatutoryAccountingPracticesByJurisdiction

thg:ExtraordinaryDividendsPayableCurrentAndNoncurrent

stpr:MI


Extraordinary
Period End2020-12-31
Value82
Percentage of ExtraordinaryDividendsPayableCurrentAndNoncurrent100.0

thg:FinancialInstrumentThatWereNotCarriedAtFairValuesIncludingHeldForSale us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis

thg:FinancialInstrumentThatWereNotCarriedAtFairValuesIncludingHeldForSale

us-gaap:FairValueInputsLevel1, us-gaap:EstimateOfFairValueFairValueDisclosure


Financial
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1061121202311821432151571791711024251376
Percentage of FinancialInstrumentThatWereNotCarriedAtFairValuesIncludingHeldForSale100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueInputsLevel2, us-gaap:EstimateOfFairValueFairValueDisclosure


Financial
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value2.82.72.72.62.64.12.12.62.11.88.78.78.4
Percentage of FinancialInstrumentThatWereNotCarriedAtFairValuesIncludingHeldForSale2.62.42.21.11.42.81.01.61.21.10.83.52.2

us-gaap:FairValueInputsLevel3, us-gaap:EstimateOfFairValueFairValueDisclosure


Financial
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value481487502489479469461470443423410395368
Percentage of FinancialInstrumentThatWereNotCarriedAtFairValuesIncludingHeldForSale452.8434.6416.3211.5262.8326.3214.0298.7246.5247.540.1157.298.0

thg:FinancialInstrumentThatWereNotCarriedAtFairValuesIncludingHeldForSale us-gaap:FairValueByMeasurementBasis

us-gaap:EstimateOfFairValueFairValueDisclosure


Financial
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value5916026257236656176796316255971442655753
Percentage of FinancialInstrumentThatWereNotCarriedAtFairValuesIncludingHeldForSale555.5537.0518.6312.7364.2429.2315.0400.4347.7348.5140.9260.6200.2

thg:PercentageOfInvestmentsNotIncludedInFairValueOfFinancialInstruments

thg:PercentageOfInvestmentsNotIncludedInFairValueOfFinancialInstruments


Percentage
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-03-312016-12-31
Value2.02.02.02.00.020.020.020.020.020.020.020.020.020.020.020.010.010.01
Percentage of PercentageOfInvestmentsNotIncludedInFairValueOfFinancialInstruments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:PercentageOfNumberOfSharesExpectedToBeReceivedUnderAgreement us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType

thg:PercentageOfNumberOfSharesExpectedToBeReceivedUnderAgreement

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreement, us-gaap:SubsequentEvent


Percentage
Period End2020-10-27
Value80.0
Percentage of PercentageOfNumberOfSharesExpectedToBeReceivedUnderAgreement100.0

thg:RealizedGainsInAccumulatedOtherComprehensiveIncomeToBeReleasedIntoIncomeFromContinuingOperationsInFuture us-gaap:StatementEquityComponents

thg:RealizedGainsInAccumulatedOtherComprehensiveIncomeToBeReleasedIntoIncomeFromContinuingOperationsInFuture

us-gaap:AccumulatedOtherComprehensiveIncome


Realized
Period End2020-12-31
Value11
Percentage of RealizedGainsInAccumulatedOtherComprehensiveIncomeToBeReleasedIntoIncomeFromContinuingOperationsInFuture100.0

thg:ShortdurationInsuranceContractsPercentageOfGrossIncurredClaims us-gaap:StatementGeographical

thg:ShortdurationInsuranceContractsPercentageOfGrossIncurredClaims

country:US


Shortduration
Period End2020-12-312017-12-31
Value4.00.05
Percentage of ShortdurationInsuranceContractsPercentageOfGrossIncurredClaims100.0100.0

thg:ValuationAllowanceOfOtherInvestments us-gaap:InvestmentType

thg:ValuationAllowanceOfOtherInvestments

us-gaap:Mortgages


Valuation
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value7900000.01300000.01100000.0900000.0700000.0
Percentage of ValuationAllowanceOfOtherInvestments100.0100.0100.0100.0100.0

us-gaap:AcceleratedShareRepurchasesSettlementPaymentOrReceipt us-gaap:ShareRepurchaseProgram

us-gaap:AcceleratedShareRepurchasesSettlementPaymentOrReceipt

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreement


Accelerated
Period End2020-12-31
Value100
Percentage of AcceleratedShareRepurchasesSettlementPaymentOrReceipt100.0

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreements


Accelerated
Period End2020-10-29
Value100
Percentage of AcceleratedShareRepurchasesSettlementPaymentOrReceipt0.0

us-gaap:AcceleratedShareRepurchasesSettlementPaymentOrReceipt us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType

thg:OctoberTwoThousandTwentyAcceleratedShareRepurchaseAgreement, us-gaap:SubsequentEvent


Accelerated
Period End2020-10-27
Value100
Percentage of AcceleratedShareRepurchasesSettlementPaymentOrReceipt0.0

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value588601687704613512627649563556909538643662716676671599728662594594724689653637695636569576637638632660775618580613642672519479541603
Percentage of AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccountsPayableAndOtherAccruedLiabilities us-gaap:ConsolidatedEntities

us-gaap:AccountsPayableAndOtherAccruedLiabilities

srt:ParentCompany


Accounts
Period End2020-12-312019-12-312018-12-312017-12-31
Value23162757.9
Percentage of AccountsPayableAndOtherAccruedLiabilities100.0100.0100.0100.0

us-gaap:AccruedInvestmentIncomeReceivable

us-gaap:AccruedInvestmentIncomeReceivable


Accrued
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value50485150515153535354535362636264606261626062626662686670707068706768697471717110653535352
Percentage of AccruedInvestmentIncomeReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AlternativeInvestment us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:AlternativeInvestment

us-gaap:FairValueInputsLevel3


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value4.04.04.03.53.53.53.53.53.53.53.53.63.6
Percentage of AlternativeInvestment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AlternativeInvestment us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis

us-gaap:FairValueInputsLevel2, us-gaap:EstimateOfFairValueFairValueDisclosure


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value2.82.72.72.62.64.12.12.62.11.88.78.78.8
Percentage of AlternativeInvestment70.067.567.574.374.3117.160.074.360.051.4248.6241.70.0

us-gaap:FairValueInputsLevel3, us-gaap:EstimateOfFairValueFairValueDisclosure


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value481487502489479469461470443423410395385368
Percentage of AlternativeInvestment12045.012180.012552.513991.413711.413417.113188.613451.412662.912111.411720.010972.20.010247.2

us-gaap:AlternativeInvestment us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType

us-gaap:FairValueMeasuredAtNetAssetValuePerShare, srt:PartnershipInterest


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value161172172174179182183176177176171165158149
Percentage of AlternativeInvestment4027.54322.54320.04980.05114.35202.95245.75042.95082.95051.44900.04608.30.04150.0

us-gaap:AlternativeInvestment us-gaap:FairValueByMeasurementBasis

us-gaap:EstimateOfFairValueFairValueDisclosure


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value484489504492482473463473445425418403394368
Percentage of AlternativeInvestment12115.012247.512620.014065.713785.713534.313248.613525.712722.912162.911968.611213.90.010247.2

us-gaap:AlternativeInvestmentMeasurementInput us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:AlternativeInvestmentMeasurementInput

us-gaap:FairValueInputsLevel3


Alternative
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0.1620.180.180.180.180.180.180.18
Percentage of AlternativeInvestmentMeasurementInput100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AlternativeInvestmentMeasurementInput us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:ValuationTechnique

us-gaap:FairValueInputsLevel3, us-gaap:ValuationTechniqueDiscountedCashFlow


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value0.1620.1620.1620.180.180.180.18
Percentage of AlternativeInvestmentMeasurementInput0.00.0100.00.00.00.0100.0

us-gaap:AlternativeInvestmentMeasurementInput us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel

srt:WeightedAverage, us-gaap:FairValueInputsLevel3


Alternative
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0.1620.180.180.180.180.180.180.18
Percentage of AlternativeInvestmentMeasurementInput100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AlternativeInvestmentMeasurementInput us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:ValuationTechnique

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:ValuationTechniqueDiscountedCashFlow


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value0.1620.1620.1620.180.180.180.18
Percentage of AlternativeInvestmentMeasurementInput0.00.0100.00.00.00.0100.0

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByMeasurementBasis

us-gaap:AssetsFairValueDisclosure

us-gaap:CarryingReportedAmountFairValueDisclosure


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value8900876088208832836478658108830479207837826373579208923093719261899987518696877685098387826483298270859185998508841382008060793777768021
Percentage of AssetsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-31
Value89308790885588658385787581298328793678418268735892109224937792709006875486958792851683948266833386048060
Percentage of AssetsFairValueDisclosure100.3100.3100.4100.4100.3100.1100.3100.3100.2100.1100.1100.0100.099.9100.1100.1100.1100.0100.0100.2100.1100.1100.0100.0100.1100.0

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperation

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperation


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1099911010910598102106106103574247102898877788079848085838187110112114115116114120118120130129122126121127128130133130
Percentage of AssetsOfDisposalGroupIncludingDiscontinuedOperation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperation us-gaap:DisposalGroupClassification

us-gaap:DiscontinuedOperationsDisposedOfBySale


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value109991101091059810210610610310310288
Percentage of AssetsOfDisposalGroupIncludingDiscontinuedOperation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0181.02.4100.0

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperation us-gaap:ProductOrService

us-gaap:AccidentAndHealthInsuranceSegment


Assets
Period End2020-12-312019-12-312018-12-31
Value908281
Percentage of AssetsOfDisposalGroupIncludingDiscontinuedOperation81.980.2142.2

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax us-gaap:InvestmentType

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax

thg:FixedMaturitiesIncludingHeldForSale


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value3803395124904552012422602071084953145
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivables


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value2.62.02.62.82.10.41.1
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax0.70.60.50.60.50.20.5

us-gaap:CommercialMortgageBackedSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value41365453472025
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax11.010.810.710.910.410.110.6

us-gaap:CorporateDebtSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value25622734131629381161
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax67.467.066.764.464.340.466.6

us-gaap:ForeignGovernmentDebtSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value0.40.40.50.50.50.30.4
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax0.10.10.10.10.10.10.2

us-gaap:MunicipalBonds


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value45386159503527342820161329
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax11.911.312.012.011.117.511.413.213.919.133.325.420.5

us-gaap:ResidentialMortgageBackedSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value22233338424317
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax5.86.86.57.89.321.67.1

us-gaap:USTreasuryAndGovernment


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value1211172020209.12.4
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax3.23.33.44.14.410.13.84.8

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax us-gaap:InvestmentType

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax

thg:FixedMaturitiesIncludingHeldForSale


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value22583.32.54.3647.67.0104213420054
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommercialMortgageBackedSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value1.53.00.20.10.32.10.1
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax6.65.26.14.07.03.31.3

us-gaap:CorporateDebtSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value8.2200.41.73.7603.9
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax36.336.012.168.086.093.651.3

us-gaap:MunicipalBonds


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value2.0110.10.10.31.41.20.40.53.49.8155.8
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax8.820.13.04.07.02.215.85.74.98.17.37.810.7

us-gaap:ResidentialMortgageBackedSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-03-312019-12-31
Value4.2100.60.30.11.1
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax18.617.918.212.00.214.5

us-gaap:USTreasuryAndGovernment


Available
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312018-12-31
Value6.7122.00.31.37.2
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax29.620.860.612.017.15.3

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis


Available
Period End2021-06-302021-03-312020-12-312020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value7198708969456493645266926402649262456204784778197688775273727232723571006842686369346943667170567145700667856815
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis us-gaap:ConsolidatedEntities

srt:ParentCompany


Available
Period End2020-12-312019-12-312018-12-312017-12-31
Value369321380281
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis5.35.06.13.7

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis us-gaap:InvestmentType

thg:FixedMaturitiesIncludingHeldForSale


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value7198708969456986663164936452669264026492627080467688
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.4129.7100.0

us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivables


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value75677172656662
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis1.10.91.00.00.01.01.0

us-gaap:CommercialMortgageBackedSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value739722705695659661666
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis10.310.210.20.00.010.210.3

us-gaap:CorporateDebtSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value3965390837703808377537493653
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis55.155.154.30.00.057.756.6

us-gaap:ForeignGovernmentDebtSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value2.22.22.24.24.24.215
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis0.00.00.00.00.00.10.2

us-gaap:MunicipalBonds


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value105310461042103391883380784880684887988810351053
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis14.614.815.00.00.012.812.512.712.613.114.114.313.213.7

us-gaap:ResidentialMortgageBackedSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value9809819781017922913905
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis13.613.814.10.00.014.114.0

us-gaap:USTreasuryAndGovernment


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value381360376353286265342414
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis5.35.15.40.00.04.15.36.6

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value2639257525482506
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value2040194519131976
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value748752809758
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value5700555056095592
Percentage of AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value272277339351
Percentage of AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue


Available
Period End2021-06-302021-03-312020-12-312020-09-30
Value1855181918441880
Percentage of AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecurities

us-gaap:AvailableForSaleSecuritiesDebtSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312010-09-30
Value7555737074547473707966256687694665986559616160927729775877797890750973407331740071427062698370846835734173787227705870076970667564416723695267946534647062846227469747974797
Percentage of AvailableForSaleSecuritiesDebtSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent

us-gaap:USGovernmentSponsoredEnterprisesDebtSecurities


Available
Period End2020-12-312019-12-312018-12-312017-12-31
Value459432396396
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

thg:MortgageParticipations


Available
Period End2020-12-312019-12-312018-12-312017-12-31
Value459396356356
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent100.091.889.989.9

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis

us-gaap:CashAndCashEquivalentsFairValueDisclosure

us-gaap:FairValueInputsLevel1, us-gaap:EstimateOfFairValueFairValueDisclosure


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value1061121202311821432151571791681020251244258376227317257282338583403373509606486
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:FairValueByMeasurementBasis

us-gaap:CarryingReportedAmountFairValueDisclosure


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value1061121202311821432151571791681020251244258376227317257282315361406338385373
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.00.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value1061121202311821432151571791681020251244258376227317257282315361406338385583403373509606486
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument, us-gaap:ValuationTechnique

us-gaap:CarryingReportedAmountFairValueDisclosure, thg:AmortizedCostOrCost, us-gaap:CostApproachValuationTechnique


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1061121202311821432151571791681020251244258376
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure, thg:AmortizedCostOrCost, us-gaap:CostApproachValuationTechnique


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1061121202311821432151571791681020251244258376
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-31
Value1061121202311821432151571791681020117138135297147189
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations us-gaap:ConsolidatedEntities

srt:ParentCompany


Cash
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value15128273210
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations12.95.781.111.06.9

us-gaap:DebtInstrumentCarryingAmount us-gaap:DebtInstrument

us-gaap:DebtInstrumentCarryingAmount

thg:SeniorDebenturesUnsecuredMaturingOctoberFifteenthTwoThousandTwentyFive


Debt
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302018-12-312017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-31
Value61616262626262627474747474748181818181120120121
Percentage of DebtInstrumentCarryingAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

thg:SeniorDebenturesUnsecuredMaturingOctoberFifteenthTwoThousandTwentyFiveAndSeniorDebenturesUnsecuredMaturingMarchFirstTwoThousandTwenty


Debt
Period End2020-12-312019-12-31
Value6162
Percentage of DebtInstrumentCarryingAmount0.0100.0

thg:SeniorDebenturesUnsecuredMaturingOnOctoberFifteenthTwoThousandTwentyFive


Debt
Period End2020-12-312019-12-312018-12-312017-12-31
Value61626262
Percentage of DebtInstrumentCarryingAmount0.0100.0100.0100.0

thg:SubordinatedDebenturesMaturingFebruaryThirdTwoThousandTwentySeven


Debt
Period End2020-12-312020-06-302020-03-312019-12-312019-09-302018-12-312017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value5050505050505959595959595959595959
Percentage of DebtInstrumentCarryingAmount0.081.180.080.080.080.095.495.480.080.080.080.080.080.073.673.673.5

us-gaap:DebtInstrumentUnamortizedDiscount

us-gaap:DebtInstrumentUnamortizedDiscount


Debt
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-312017-12-312016-12-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value6.16.59.19.29.39.49.810101.51.51.61.71.92.1
Percentage of DebtInstrumentUnamortizedDiscount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrumentUnamortizedDiscount us-gaap:DebtInstrument

thg:SubordinatedDebenturesUnsecuredMaturingMarchThirtyTwoThousandFiftyThree


Debt
Period End2020-09-19
Value6.1
Percentage of DebtInstrumentUnamortizedDiscount0.0

us-gaap:DebtLongtermAndShorttermCombinedAmount

us-gaap:DebtLongtermAndShorttermCombinedAmount


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-31
Value781781780780652707653667777
Percentage of DebtLongtermAndShorttermCombinedAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtLongtermAndShorttermCombinedAmount us-gaap:ConsolidatedEntities

srt:ParentCompany


Debt
Period End2020-12-312019-12-31
Value905778
Percentage of DebtLongtermAndShorttermCombinedAmount116.0119.1

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLoss us-gaap:InvestmentType

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLoss

thg:FixedMaturitiesIncludingHeldForSale


Debt
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-31
Value100000.0100000.01600000.03800000.06200000.00
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss100.0100.0100.0100.0100.00.0

thg:MortgageLoans


Debt
Period End2020-09-302020-06-302019-12-31
Value7800000.06100000.01300000.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss487.5160.50.0

us-gaap:CorporateDebtSecurities


Debt
Period End2021-06-302020-12-312020-09-302020-06-302020-03-31
Value100000.0100000.01600000.03800000.06200000.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss100.0100.0100.0100.0100.0

us-gaap:Mortgages


Debt
Period End2021-06-302021-03-312020-12-312019-12-31
Value7900000.07900000.07900000.01300000.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss7900.00.07900.00.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.51.60.71.60.52.0651524972031
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger us-gaap:InvestmentSecondaryCategorization

thg:InvestmentGrade


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0.51.60.71.60.52.056143450195517581266783
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger100.0100.0100.0100.0100.0100.086.394.190.696.30.00.00.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

thg:InvestmentGrade, us-gaap:CommercialMortgageBackedSecurities


Debt
Period End2021-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1.00.925532261759961
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger62.51.416.410.811.20.00.00.0

thg:InvestmentGrade, us-gaap:CorporateDebtSecurities


Debt
Period End2020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1.44.724176993781633395
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger87.57.215.735.648.90.00.00.0

thg:InvestmentGrade, us-gaap:MunicipalBonds


Debt
Period End2021-06-302021-03-312020-12-312020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0.50.50.70.65.61538192248161101
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger100.031.2100.030.08.510.27.89.50.00.00.0

thg:InvestmentGrade, us-gaap:ResidentialMortgageBackedSecurities


Debt
Period End2021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0.10.20.51.43458128352323241159
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger6.212.5100.070.052.438.325.717.40.00.00.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1078161834532719514883682663344
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months us-gaap:InvestmentSecondaryCategorization

thg:InvestmentGrade


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1036155334128710413443412251327199230521086
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months96.196.098.787.653.790.392.784.738.961.60.00.00.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

thg:BelowInvestmentGrade, us-gaap:CorporateDebtSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value42644.64090144274020171858748
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months3.94.01.312.446.39.77.315.361.138.40.00.00.0

thg:InvestmentGrade, us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivables


Debt
Period End2021-03-312020-06-302020-03-312019-09-302018-12-312018-09-302017-12-31
Value4.61.4210.5426934
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months0.30.71.40.20.00.00.0

thg:InvestmentGrade, us-gaap:CommercialMortgageBackedSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value7284333130111401.80.40.3293476139
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months6.75.29.69.715.57.511.00.71.20.70.00.00.0

thg:InvestmentGrade, us-gaap:CorporateDebtSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value298515538641114586793.51512771589386
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months27.731.815.526.321.377.023.430.010.334.40.00.00.0

thg:InvestmentGrade, us-gaap:MunicipalBonds


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1763721928176272296.49.7110251183
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months16.323.05.68.68.74.219.711.018.921.80.00.00.0

thg:InvestmentGrade, us-gaap:ResidentialMortgageBackedSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-03-312018-12-312018-09-302017-12-31
Value3044059488143.369762.1201419196
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months28.225.027.326.97.20.218.828.94.70.00.00.0

thg:InvestmentGrade, us-gaap:USTreasuryAndGovernment


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302018-12-312018-09-302017-12-31
Value185171140520.573372.966243146
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months17.210.640.716.10.319.813.98.60.00.00.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value22583.32.54.3646.15.00.61.2
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss us-gaap:InvestmentSecondaryCategorization

thg:InvestmentGrade


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value21563.31.61.2533.91.80.10.938708.4
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss95.697.6100.064.027.982.863.936.016.775.00.00.00.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

thg:BelowInvestmentGrade, us-gaap:CorporateDebtSecurities


Debt
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1.01.40.93.1112.23.20.50.38.12.51.5
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss4.42.436.072.117.236.164.083.325.00.00.00.0

thg:InvestmentGrade, us-gaap:CommercialMortgageBackedSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-312018-09-302017-12-31
Value1.53.00.20.10.32.10.13.4100.9
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss6.65.26.14.07.03.31.60.00.00.0

thg:InvestmentGrade, us-gaap:CorporateDebtSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value7.2190.40.80.6490.70.90.10.930363.0
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss31.933.612.132.014.076.411.518.016.775.00.00.00.0

thg:InvestmentGrade, us-gaap:MunicipalBonds


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-312018-09-302017-12-31
Value2.0110.10.10.31.41.10.20.85.81.7
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss8.820.13.04.07.02.218.04.00.00.00.0

thg:InvestmentGrade, us-gaap:ResidentialMortgageBackedSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-03-312019-12-312019-09-302018-12-312018-09-302017-12-31
Value4.2100.60.30.10.70.42.6101.4
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss18.617.918.212.00.211.58.00.00.00.0

thg:InvestmentGrade, us-gaap:USTreasuryAndGovernment


Debt
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312019-09-302018-12-312018-09-302017-12-31
Value6.7122.00.31.30.31.16.91.1
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss29.620.860.612.021.36.00.00.00.0

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPosition

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPosition


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1079161934632919514904344185312076
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPosition100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPosition us-gaap:InvestmentSecondaryCategorization

thg:InvestmentGrade


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1037155534128810513463983684641983375043181869
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPosition96.196.098.787.653.890.391.788.187.395.50.00.00.0

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPosition us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

thg:BelowInvestmentGrade, us-gaap:CorporateDebtSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value42644.640901443649679223913087
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPosition3.94.01.312.446.29.78.311.912.74.50.00.00.0

thg:InvestmentGrade, us-gaap:AssetBackedSecuritiesSecuritizedLoansAndReceivables


Debt
Period End2021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value4.61.4211.73.88.231607537
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPosition0.30.71.40.40.91.51.50.00.00.0

thg:InvestmentGrade, us-gaap:CommercialMortgageBackedSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value7285333130111412654227468575201
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPosition6.75.39.69.615.57.59.66.410.210.90.00.00.0

thg:InvestmentGrade, us-gaap:CorporateDebtSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value298515538741114591103180100820592223782
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPosition27.731.815.426.621.276.921.024.833.948.60.00.00.0

thg:InvestmentGrade, us-gaap:MunicipalBonds


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value17637320281763784445202358413285
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPosition16.423.15.88.68.74.218.010.78.59.70.00.00.0

thg:InvestmentGrade, us-gaap:ResidentialMortgageBackedSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value3044059488144.7103135128354524660355
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPosition28.225.027.326.87.50.323.832.324.117.10.00.00.0

thg:InvestmentGrade, us-gaap:USTreasuryAndGovernment


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value185171140520.5825447158276367208
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPosition17.210.640.616.00.318.913.09.07.60.00.00.0

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value22583.32.54.3647.67.01042
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss us-gaap:InvestmentSecondaryCategorization

thg:InvestmentGrade


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value21563.31.61.2534.53.05.03511615030
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss95.697.6100.064.027.982.859.242.948.583.80.00.00.0

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss us-gaap:InvestmentSecondaryCategorization, us-gaap:InvestmentType

thg:BelowInvestmentGrade, us-gaap:CorporateDebtSecurities


Debt
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1.01.40.93.1113.14.05.36.8188.87.9
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss4.42.436.072.117.240.857.151.516.20.00.00.0

thg:InvestmentGrade, us-gaap:CommercialMortgageBackedSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-06-302019-03-312018-12-312018-09-302017-12-31
Value1.53.00.20.10.32.10.10.22.49.8152.5
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss6.65.26.14.07.03.31.31.95.70.00.00.0

thg:InvestmentGrade, us-gaap:CorporateDebtSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value7.2190.40.80.6490.81.32.520737713
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss31.933.612.132.014.076.410.518.624.349.00.00.00.0

thg:InvestmentGrade, us-gaap:MunicipalBonds


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value2.0110.10.10.31.41.20.40.53.49.8155.8
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss8.820.13.04.07.02.215.85.74.98.10.00.00.0

thg:InvestmentGrade, us-gaap:ResidentialMortgageBackedSecurities


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value4.2100.60.30.11.10.91.56.114254.9
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss18.617.918.212.00.214.512.914.614.50.00.00.0

thg:InvestmentGrade, us-gaap:USTreasuryAndGovernment


Debt
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value6.7122.00.31.30.40.32.57.2143.2
Percentage of DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss29.620.860.612.017.15.72.96.00.00.00.0

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredIncomeTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value271207113179262217289
Percentage of DeferredIncomeTaxLiabilities100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredPolicyAcquisitionCosts

us-gaap:DeferredPolicyAcquisitionCosts


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value504491477482461465467474456449450456564554550562547525517537522509508527522533525540540520506521509494489501495468498509348339345286
Percentage of DeferredPolicyAcquisitionCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsOther

us-gaap:DeferredTaxAssetsOther


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value168.3162954531074606361
Percentage of DeferredTaxAssetsOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value6.07.6142344394538564538
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value150139129115183179175185190178170
Percentage of DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value2421181828262730312928
Percentage of DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value100989590141134129123115123120
Percentage of DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesInvestments

us-gaap:DeferredTaxLiabilitiesInvestments


Deferred
Period End2020-12-312019-12-312017-12-312016-12-312014-12-312013-12-312012-12-31
Value146874827448.443
Percentage of DeferredTaxLiabilitiesInvestments100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value-67400000.0-77300000.0-109700000.0-118500000.0-150400000.0-119400000.0-126900000.0-118700000.0
Percentage of DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value2.884.04.50.03880.04250.0475
Percentage of DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate100.0100.0100.0100.0100.0100.0

us-gaap:QualifiedPlan


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value3.03.754.50.03880.04250.0488
Percentage of DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate104.293.8100.0100.0100.0102.7

us-gaap:DefinedBenefitPlanBenefitObligation us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanBenefitObligation

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-312019-12-312018-12-31
Value333133
Percentage of DefinedBenefitPlanBenefitObligation100.0100.0100.0

us-gaap:QualifiedPlan


Defined
Period End2020-12-312019-12-312018-12-31
Value483472469
Percentage of DefinedBenefitPlanBenefitObligation1464.51490.51389.1

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-31
Value11
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter100.0

us-gaap:QualifiedPlan


Defined
Period End2020-12-31
Value152
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter1373.0

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-31
Value2.9
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths100.0

us-gaap:QualifiedPlan


Defined
Period End2020-12-31
Value39
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths1358.6

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-31
Value2.5
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive100.0

us-gaap:QualifiedPlan


Defined
Period End2020-12-31
Value34
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive1368.0

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-31
Value2.6
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour100.0

us-gaap:QualifiedPlan


Defined
Period End2020-12-31
Value35
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour1376.9

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-31
Value2.7
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree100.0

us-gaap:QualifiedPlan


Defined
Period End2020-12-31
Value37
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree1388.9

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-31
Value2.9
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo100.0

us-gaap:QualifiedPlan


Defined
Period End2020-12-31
Value38
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo1313.8

us-gaap:DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-31
Value2.9
Percentage of DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear100.0

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets us-gaap:DefinedBenefitPlanByPlanAssetCategories

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets

us-gaap:DefinedBenefitPlanDebtSecurity


Defined
Period End2020-12-312019-12-312018-12-31
Value192225
Percentage of DefinedBenefitPlanFairValueOfPlanAssets100.0100.0100.0

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis

us-gaap:DefinedBenefitPlanDebtSecurity, us-gaap:FairValueInputsLevel1, us-gaap:EstimateOfFairValueFairValueDisclosure


Defined
Period End2020-12-312019-12-31
Value1010
Percentage of DefinedBenefitPlanFairValueOfPlanAssets54.546.7

us-gaap:DefinedBenefitPlanDebtSecurity, us-gaap:FairValueInputsLevel3, us-gaap:EstimateOfFairValueFairValueDisclosure


Defined
Period End2020-12-312019-12-31
Value1922
Percentage of DefinedBenefitPlanFairValueOfPlanAssets100.0100.0

us-gaap:MoneyMarketFunds, us-gaap:FairValueInputsLevel1, us-gaap:EstimateOfFairValueFairValueDisclosure


Defined
Period End2020-12-312019-12-31
Value117.8
Percentage of DefinedBenefitPlanFairValueOfPlanAssets59.234.1

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByMeasurementBasis

us-gaap:DefinedBenefitPlanDebtSecurity, us-gaap:EstimateOfFairValueFairValueDisclosure


Defined
Period End2020-12-312019-12-31
Value2933
Percentage of DefinedBenefitPlanFairValueOfPlanAssets154.5146.7

us-gaap:MoneyMarketFunds, us-gaap:EstimateOfFairValueFairValueDisclosure


Defined
Period End2020-12-312019-12-31
Value117.8
Percentage of DefinedBenefitPlanFairValueOfPlanAssets59.234.1

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis

us-gaap:FairValueInputsLevel1, us-gaap:EstimateOfFairValueFairValueDisclosure


Defined
Period End2020-12-312019-12-31
Value2118
Percentage of DefinedBenefitPlanFairValueOfPlanAssets113.680.8

us-gaap:FairValueInputsLevel3, us-gaap:EstimateOfFairValueFairValueDisclosure


Defined
Period End2020-12-312019-12-31
Value1922
Percentage of DefinedBenefitPlanFairValueOfPlanAssets100.0100.0

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets us-gaap:FairValueByMeasurementBasis

us-gaap:EstimateOfFairValueFairValueDisclosure


Defined
Period End2020-12-312019-12-31
Value4041
Percentage of DefinedBenefitPlanFairValueOfPlanAssets213.6180.8

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets us-gaap:RetirementPlanTaxStatus

us-gaap:QualifiedPlan


Defined
Period End2020-12-312019-12-312018-12-31
Value510487450
Percentage of DefinedBenefitPlanFairValueOfPlanAssets2673.82129.31746.9

us-gaap:DefinedBenefitPlanFundedStatusOfPlan us-gaap:RetirementPlanTaxStatus

us-gaap:DefinedBenefitPlanFundedStatusOfPlan

us-gaap:NonqualifiedPlan


Defined
Period End2020-12-312019-12-31
Value-33.0-31.7
Percentage of DefinedBenefitPlanFundedStatusOfPlan100.0100.0

us-gaap:QualifiedPlan


Defined
Period End2020-12-312019-12-31
Value2715
Percentage of DefinedBenefitPlanFundedStatusOfPlan-83.0-47.6

us-gaap:DefinedBenefitPlanWeightedAverageAssetAllocations us-gaap:DefinedBenefitPlanByPlanAssetCategories

us-gaap:DefinedBenefitPlanWeightedAverageAssetAllocations

us-gaap:DefinedBenefitPlanDebtSecurity


Defined
Period End2020-12-312019-12-31
Value87.088.0
Percentage of DefinedBenefitPlanWeightedAverageAssetAllocations100.0100.0

us-gaap:MoneyMarketFunds


Defined
Period End2020-12-312019-12-31
Value3.02.0
Percentage of DefinedBenefitPlanWeightedAverageAssetAllocations3.42.3

us-gaap:DividendsPayableCurrentAndNoncurrent us-gaap:StatutoryAccountingPracticesByJurisdiction

us-gaap:DividendsPayableCurrentAndNoncurrent

stpr:NH


Dividends
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value2451401402960.00.00.00.00.0
Percentage of DividendsPayableCurrentAndNoncurrent100.0100.0100.0100.00.00.00.00.00.0

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized us-gaap:AwardType

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized

thg:UnvestedRestrictedStockUnitsAndPerformanceAndMarketBasedRestrictedStockUnits


Employee
Period End2020-12-312019-12-31
Value2522
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized100.0100.0

us-gaap:EmployeeStockOption


Employee
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value2.62.73.73.45.03.74.8
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized10.411.80.00.00.00.00.0

us-gaap:EquitySecuritiesFvNiMeasurementInput us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:ValuationTechnique

us-gaap:EquitySecuritiesFvNiMeasurementInput

us-gaap:FairValueInputsLevel3, us-gaap:EquitySecurities, thg:InternalModelPricingApproachValuationTechnique


Equity
Period End2021-06-302021-03-312020-12-312019-12-31
Value5.65.65.61.27
Percentage of EquitySecuritiesFvNiMeasurementInput100.0100.0100.0100.0

us-gaap:EquitySecuritiesFvNiMeasurementInput us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType, us-gaap:ValuationTechnique

srt:WeightedAverage, us-gaap:FairValueInputsLevel3, us-gaap:EquitySecurities, thg:InternalModelPricingApproachValuationTechnique


Equity
Period End2021-06-302021-03-312020-12-312019-12-31
Value5.65.65.61.27
Percentage of EquitySecuritiesFvNiMeasurementInput100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312013-03-202012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value27282925252931313238394143444648515455576060605860636167677010410510310510510210399969810374726771717862
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FederalHomeLoanBankStock

us-gaap:FederalHomeLoanBankStock


Federal
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312013-09-302013-06-302013-03-312012-12-312012-03-312011-03-31
Value2600000.02100000.08700000.08500000.09800000.08900000.09300000.09300000.09300000.09300000.09300000.09700000.09700000.09400000.0
Percentage of FederalHomeLoanBankStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestPayableCurrentAndNoncurrent us-gaap:ConsolidatedEntities

us-gaap:InterestPayableCurrentAndNoncurrent

srt:ParentCompany


Interest
Period End2020-12-312019-12-312018-12-312017-12-31
Value107.87.88.1
Percentage of InterestPayableCurrentAndNoncurrent100.0100.0100.0100.0

us-gaap:InvestmentOwnedUnrecognizedUnrealizedAppreciationDepreciationNet us-gaap:InvestmentType, us-gaap:StatementEquityComponents

us-gaap:InvestmentOwnedUnrecognizedUnrealizedAppreciationDepreciationNet

us-gaap:DebtSecurities, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Investment
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value428216-27.2110127
Percentage of InvestmentOwnedUnrecognizedUnrealizedAppreciationDepreciationNet100.0100.0100.0100.0100.0

us-gaap:InvestmentOwnedUnrecognizedUnrealizedAppreciationDepreciationNet us-gaap:StatementEquityComponents

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Investment
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value428216-27.2205186149300259426308218107
Percentage of InvestmentOwnedUnrecognizedUnrealizedAppreciationDepreciationNet100.0100.0100.0186.6146.30.00.00.00.00.00.00.0

us-gaap:Investments

us-gaap:Investments


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value89558804884687278301782779968239782277447287730090209021904190738719853084498496817980097953797077098212825080237827774475937354710673667478744471317017672166684906501449654717
Percentage of Investments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentsFairValueDisclosure us-gaap:BalanceSheetLocation, us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument, us-gaap:ValuationTechnique

us-gaap:InvestmentsFairValueDisclosure

us-gaap:OtherInvestments, us-gaap:CarryingReportedAmountFairValueDisclosure, thg:AmortizedCostOrCost, us-gaap:CostApproachValuationTechnique


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value455459470459461463443449428421414403393380512
Percentage of InvestmentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherInvestments, us-gaap:CarryingReportedAmountFairValueDisclosure, thg:FairValueThroughNetIncome, us-gaap:ValuationTechniqueDiscountedCashFlow


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value165176176177182185187180181180175285122
Percentage of InvestmentsFairValueDisclosure36.338.537.638.739.540.042.240.142.342.842.270.923.9

us-gaap:OtherInvestments, us-gaap:EstimateOfFairValueFairValueDisclosure, thg:AmortizedCostOrCost, us-gaap:CostApproachValuationTechnique


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value484489504492482473463473445425418403394374518
Percentage of InvestmentsFairValueDisclosure106.5106.6107.3107.1104.6102.2104.6105.4103.8101.0101.1100.1100.498.5101.1

us-gaap:OtherInvestments, us-gaap:EstimateOfFairValueFairValueDisclosure, thg:FairValueThroughNetIncome, us-gaap:ValuationTechniqueDiscountedCashFlow


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value165176176177182185187180181180175285122
Percentage of InvestmentsFairValueDisclosure36.338.537.638.739.540.042.240.142.342.842.270.923.9

us-gaap:InvestmentsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasuredAtNetAssetValuePerShare


Investments
Period End2020-12-312019-12-312018-12-312017-12-31
Value467446370373
Percentage of InvestmentsFairValueDisclosure99.3100.689.472.8

us-gaap:InvestmentsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-31
Value791790748649618596731730691662623726809824844800840850829824799780812765740784847741723652595659632556432467324
Percentage of InvestmentsFairValueDisclosure173.9172.0159.2141.2134.0128.6165.0162.6161.1157.3150.6180.2206.0216.8164.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-31
Value7360719672787292689764506503675864106366599059047559757275827718733171457126722069506854678269026688718771777087692769436845654963266659689667736233
Percentage of InvestmentsFairValueDisclosure1617.61565.51547.71585.91494.61391.61467.11504.11494.61510.31445.61464.91923.61991.21478.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-31
Value272829252529313132383939434446485154555760606058606361676770104105103105102103102
Percentage of InvestmentsFairValueDisclosure6.06.16.35.65.56.37.07.17.59.29.69.811.011.69.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:InvestmentsFairValueDisclosure us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument, us-gaap:InvestmentType, us-gaap:ValuationTechnique

us-gaap:CarryingReportedAmountFairValueDisclosure, thg:FairValueThroughAccumulatedOtherComprehensiveIncome, us-gaap:DebtSecurities, us-gaap:ValuationTechniqueDiscountedCashFlow


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value7555737074547473707966256687694665986559616178997779
Percentage of InvestmentsFairValueDisclosure1660.61603.31585.01625.31533.91429.31508.51546.01538.61556.21486.81959.71517.1

us-gaap:CarryingReportedAmountFairValueDisclosure, thg:FairValueThroughNetIncome, us-gaap:EquitySecurities, us-gaap:ValuationTechniqueDiscountedCashFlow


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value618641598490458447575570531504464575
Percentage of InvestmentsFairValueDisclosure136.0139.4127.3106.799.496.4129.9127.0123.9119.7112.1142.6

us-gaap:EstimateOfFairValueFairValueDisclosure, thg:FairValueThroughAccumulatedOtherComprehensiveIncome, us-gaap:DebtSecurities, us-gaap:ValuationTechniqueDiscountedCashFlow


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value7555737074547473707966256687694665986559616178997779
Percentage of InvestmentsFairValueDisclosure1660.61603.31585.01625.31533.91429.31508.51546.01538.61556.21486.81959.71517.1

us-gaap:EstimateOfFairValueFairValueDisclosure, thg:FairValueThroughNetIncome, us-gaap:EquitySecurities, us-gaap:ValuationTechniqueDiscountedCashFlow


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value618641598490458447575570531504464575
Percentage of InvestmentsFairValueDisclosure136.0139.4127.3106.799.496.4129.9127.0123.9119.7112.1142.6

us-gaap:InvestmentsFairValueDisclosure us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-31
Value8178801580567967754170757266752071337067665366718412844184748567822280508012810378107695765577277490803580867896771876657544731470637321743173456660
Percentage of InvestmentsFairValueDisclosure1797.51743.61713.11732.71634.11526.51639.11673.81663.31676.81605.71654.92140.62219.61652.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation

us-gaap:LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value12112012011811811611611711811822366011511511589898986878888888990113114115115116121121122123126126128127129128126129129134
Percentage of LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation us-gaap:ProductOrService

us-gaap:AccidentAndHealthInsuranceSegment


Liabilities
Period End2020-12-312019-12-312018-12-31
Value898481
Percentage of LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation74.372.2366.7

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-312012-12-312011-12-31
Value63436223602459455837572456545550547853815304518875067519774576357162710369496802677867226574660665916483639164356448203020741931
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent

us-gaap:AsbestosIssue


Liability
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value575557596157
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense1.01.01.10.80.90.9

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense us-gaap:StatementBusinessSegments

thg:CommercialAndOtherLines


Liability
Period End2020-12-312019-12-312018-12-31
Value411638153596
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense68.367.567.8

thg:PersonalLinesSegment


Liability
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value19071839170716191554
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense31.732.532.220.922.4

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense us-gaap:StatementBusinessSegments, us-gaap:Subsegments

thg:CommercialAndOtherLines, thg:CommercialAutomobileLine


Liability
Period End2020-12-312019-12-312018-12-31
Value504467433
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense8.48.38.2

thg:CommercialAndOtherLines, thg:CommercialMultiplePerilLine


Liability
Period End2020-12-312019-12-312018-12-31
Value142912981206
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense23.723.022.7

thg:CommercialAndOtherLines, thg:GeneralLiabilityAndUmbrellaOccurrence


Liability
Period End2020-12-312019-12-312018-12-31
Value612575534
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense10.210.210.1

thg:CommercialAndOtherLines, thg:GeneralLiabilityClaimsMade


Liability
Period End2020-12-312019-12-312018-12-31
Value323268245
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense5.44.74.6

thg:CommercialAndOtherLines, thg:OtherLines


Liability
Period End2020-12-312019-12-312018-12-31
Value451409400
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense7.57.27.6

thg:CommercialAndOtherLines, thg:WorkersCompensationLine


Liability
Period End2020-12-312019-12-312018-12-31
Value795795775
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense13.214.114.6

thg:PersonalLinesSegment, thg:Homeowners


Liability
Period End2020-12-312019-12-312018-12-31
Value210172158
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense3.53.03.0

thg:PersonalLinesSegment, thg:OtherPersonalLines


Liability
Period End2020-12-312019-12-312018-12-31
Value474035
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense0.80.70.7

thg:PersonalLinesSegment, thg:PersonalAutomobileLines


Liability