WRB


Line plots across dimensions of each concept
Tables

Table of contents



us-gaap:CommonStockValue

us-gaap:CommonStockParOrStatedValuePerShare

us-gaap:CommonStockSharesIssued

us-gaap:CommonStockSharesOutstanding

us-gaap:CommonStockSharesAuthorized

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic
us-gaap:AwardType, us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:Revenues
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:NetInvestmentIncome
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:RealizedInvestmentGainsLosses

us-gaap:OtherIncome

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet

us-gaap:InterestExpense

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

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

us-gaap:NetIncomeLoss
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:Assets
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:Liabilities
us-gaap:ConsolidatedEntities

us-gaap:LiabilitiesAndStockholdersEquity
us-gaap:ConsolidatedEntities

us-gaap:StockholdersEquity
us-gaap:ConsolidatedEntities

us-gaap:CashAndCashEquivalentsAtCarryingValue
us-gaap:ConsolidatedEntities

us-gaap:PropertyPlantAndEquipmentNet
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures

us-gaap:Goodwill
us-gaap:BalanceSheetLocation
us-gaap:IntangibleAssetsNetExcludingGoodwill
us-gaap:DebtInstrument
us-gaap:LongTermDebt
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType

us-gaap:MinorityInterest

us-gaap:StockholdersEquity
us-gaap:ConsolidatedEntities

us-gaap:CommonStockValue

us-gaap:RetainedEarningsAccumulatedDeficit
us-gaap:ConsolidatedEntities

us-gaap:TreasuryStockValue
us-gaap:ConsolidatedEntities

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
us-gaap:ConsolidatedEntities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:ProfitLoss
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:PaymentsForRepurchaseOfCommonStock
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentInterestRateStatedPercentage
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod

us-gaap:ShareBasedCompensation

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
us-gaap:StatementEquityComponents
us-gaap:AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition

us-gaap:AllocatedShareBasedCompensationExpenseNetOfTax

us-gaap:AssumedPremiumsEarned

us-gaap:AssumedPremiumsWritten

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:CededPremiumsEarned

us-gaap:CededPremiumsWritten

us-gaap:CommonStockDividendsPerShareCashPaid

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded
us-gaap:FinancialInstrument

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal
us-gaap:FinancialInstrument

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold
us-gaap:FinancialInstrument

us-gaap:DepreciationAndAmortization

us-gaap:DirectPremiumsEarned

us-gaap:DirectPremiumsWritten
us-gaap:StatementEquityComponents
us-gaap:Dividends

us-gaap:EffectOfExchangeRateOnCashAndCashEquivalents

us-gaap:EquityMethodInvestmentRealizedGainLossOnDisposal
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySales

us-gaap:FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease

us-gaap:GainLossOnInvestments

us-gaap:GainLossOnSaleOfOtherInvestments

us-gaap:GainLossOnSalesOfLoansNet

us-gaap:IncomeLossFromEquityMethodInvestments
us-gaap:InvestmentType

us-gaap:IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions

us-gaap:IncomeTaxesPaidNet

us-gaap:IncreaseDecreaseInBrokerDealerRelatedReceivablesPayablesNet

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes

us-gaap:IncreaseDecreaseInDeferredPolicyAcquisitionCosts

us-gaap:IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities

us-gaap:IncreaseDecreaseInPremiumsReceivable

us-gaap:IncreaseDecreaseInReinsuranceRecoverable

us-gaap:IncreaseDecreaseInTradingSecurities

us-gaap:IncreaseDecreaseInUnearnedPremiums

us-gaap:IncreaseDecreaseInUnearnedPremiumsNet

us-gaap:InsuranceCommissionsAndFees

us-gaap:InterestPaid

us-gaap:InvestmentIncomeInterestAndDividend
us-gaap:InvestmentType

us-gaap:InvestmentIncomeInvestmentExpense

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1

us-gaap:MarketableSecuritiesGainLoss

us-gaap:MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest
us-gaap:StatementEquityComponents
us-gaap:NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance

us-gaap:OperatingCostsAndExpenses

us-gaap:OperatingLeaseCost

us-gaap:OperatingLeasePayments
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToNoncontrollingInterest

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax
us-gaap:FinancialInstrument
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax

us-gaap:OtherComprehensiveIncomeLossBeforeTax
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossTax

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherCostAndExpenseOperating

us-gaap:OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet

us-gaap:PaymentsForLossesAndLossAdjustmentExpense

us-gaap:PaymentsForProceedsFromLoansReceivable

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesEquity

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired

us-gaap:PaymentsToAcquireRealEstate

us-gaap:PremiumsWrittenNet

us-gaap:ProceedsFromDivestitureOfBusinessesNetOfCashDivested

us-gaap:ProceedsFromIssuanceOfDebt

us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesEquity

us-gaap:ProvisionForLoanLossesExpensed
us-gaap:FinancingReceivablePortfolioSegment
us-gaap:StatementEquityComponents
us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax

us-gaap:ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodValueTreasuryStockReissued

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense
us-gaap:StatementEquityComponents
us-gaap:TreasuryStockValueAcquiredCostMethod

us-gaap:UnrealizedGainLossOnInvestments

us-gaap:WeightedAverageNumberOfSharesRestrictedStock
us-gaap:StatementEquityComponents
wrb:AdjustmentstoAdditionalPaidinCapitalStockIssuedDuringPeriodValueStockOptionsExercisedValueRestrictedStockIssuedNetofTaxBenefitExpense

wrb:AvailableforSaleandHeldtoMaturityRealizedGainsDebtSecuritiesExcludingOtherthanTemporaryImpairmentsandAllowances

wrb:AvailableforSaleandHeldtoMaturityRealizedLossesDebtSecuritiesExcludingOtherthanTemporaryImpairmentsandAllowances

wrb:AvailableforsaleSecuritiesGrossRealizedGainLossEquitySecuritiesExcludingOtherthanTemporaryImpairments

wrb:ChangeinUnrealizedGainlossonInvestmentsIncludingPortionAttributabletoNoncontrollingInterest

wrb:ChangeinUnrealizedGainlossonInvestmentsIncludingPortionAttributabletoNoncontrollingInterestNetofTax

wrb:ChangeinUnrealizedGainlossonInvestmentstax

wrb:DebtSecuritiesAllowanceforCreditLossPeriodIncreaseDecrease

wrb:ExpensesFromWhollyOwnedInvestees
us-gaap:StatementBusinessSegments
wrb:FavorableReserveDevelopmentNetOfPremiumOffsets

wrb:IncomeBeforeIncomeTaxes
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

wrb:InvestmentsAllowanceforCreditLossPeriodIncreaseDecrease

wrb:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsUndiscountedBasisPriorYearsIncreaseDecrease

wrb:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredLossReserveDiscountAccretion

wrb:LiabilityforUnpaidClaimsandClaimsAdjustmentExpenseForeignExchangeTranslation

wrb:LiabilityforUnpaidClaimsandClaimsAdjustmentExpenseIncurredClaimsAdjustment

wrb:MarketableSecuritiesRealizedGainLossExcludingOtherthanTemporaryImpairmentsNetofTax

wrb:OperatingLeaseRightOfUseAssetAccumulatedDepreciation
us-gaap:StatementEquityComponents
wrb:OtherComprehensiveIncomeLossSecuritiesAvailableforSaleWithAllowanceforCreditLossUnrealizedHoldingGainLossArisingDuringPeriodafterTax
us-gaap:StatementEquityComponents
wrb:OtherComprehensiveIncomeUnrealizedGainsonOtherThanTemporarilyImpairedSecurities

wrb:OtherRevenues
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

wrb:PaymentForStockOptionsExercisedNet

wrb:PaymentstoAcquirePropertyPlantandEquipmentNet

wrb:ProceedsFromPaymentsToEquityMethodInvestments

wrb:REalEstateRealizedGainLossonDisposal

wrb:RealizedGainLossonInvestmentsIncludingEquityMethodInvestmentsExcludingOtherthanTemporaryImpairmentsandAllowances

wrb:RealizedGainLossonMarketableSecuritiesEquityMethodInvestmentsandOtherInvestmentsBeforeTax

wrb:RealizedGainLossonMarketableSecuritiesEquityMethodInvestmentsandOtherInvestmentsNetofTax

wrb:RealizedGainLossonMarketableSecuritiesEquityMethodInvestmentsandOtherInvestmentsTax

wrb:RevenuesFromWhollyOwnedInvestees
us-gaap:AwardType
wrb:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue
us-gaap:StatementBusinessSegments
wrb:UnfavorableReserveDevelopmentNetOfPremiumOffsets

us-gaap:AccruedInvestmentIncomeReceivable

us-gaap:AdditionalPaidInCapitalCommonStock
us-gaap:ConsolidatedEntities

us-gaap:AllowanceForLoanAndLeaseLossesRealEstate
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:AssetsFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis
us-gaap:ConsolidatedEntities
us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementBasis
us-gaap:AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax
us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementBasis
us-gaap:AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax
us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementBasis
us-gaap:AvailableForSaleEquitySecuritiesAmortizedCostBasis
us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementBasis
us-gaap:AvailableForSaleSecurities
us-gaap:FinancialInstrument
us-gaap:AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
us-gaap:FinancialInstrument, us-gaap:InvestmentSecondaryCategorization
us-gaap:InvestmentSecondaryCategorization
us-gaap:FinancialInstrument
us-gaap:AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
us-gaap:FinancialInstrument
us-gaap:AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue

us-gaap:AvailableForSaleSecuritiesEquitySecurities
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementFrequency
us-gaap:FinancialInstrument, us-gaap:InvestmentSecondaryCategorization
us-gaap:AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1
us-gaap:InvestmentSecondaryCategorization
us-gaap:FairValueByMeasurementBasis
us-gaap:CashAndCashEquivalentsFairValueDisclosure
us-gaap:DebtInstrument
us-gaap:DebtInstrumentFaceAmount
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLoss
us-gaap:FinancialInstrument
us-gaap:FinancialInstrument, wrb:CumulativeEffectPeriodOfAdoption
wrb:CumulativeEffectPeriodOfAdoption

us-gaap:DebtSecuritiesAvailableForSaleAndHeldToMaturity
us-gaap:ConsolidatedEntities

us-gaap:DebtSecuritiesHeldToMaturityAllowanceForCreditLoss
us-gaap:FinancialInstrument
wrb:CumulativeEffectPeriodOfAdoption

us-gaap:DeferredIncomeTaxAssetsNet
us-gaap:ConsolidatedEntities

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredIncomeTaxLiabilitiesNet
us-gaap:ConsolidatedEntities

us-gaap:DeferredPolicyAcquisitionCosts

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards

us-gaap:DeferredTaxAssetsOther

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets

us-gaap:DeferredTaxLiabilitiesInvestments

us-gaap:DeferredTaxLiabilitiesOther

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment

us-gaap:DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities

us-gaap:DepositContractsLiabilities
us-gaap:DerivativeInstrumentRisk, us-gaap:Position
us-gaap:DerivativeFairValueOfDerivativeNet
us-gaap:DerivativeInstrumentRisk, us-gaap:Position
us-gaap:DerivativeNotionalAmount

us-gaap:DevelopmentInProcess
us-gaap:ConsolidatedEntities
us-gaap:DueToAffiliateCurrentAndNoncurrent

us-gaap:EquityMethodInvestments
us-gaap:InvestmentType

us-gaap:EquitySecuritiesFvNi
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementBasis
us-gaap:EquitySecuritiesFvNiCost
us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FinancialInstrumentsSoldNotYetPurchasedAtFairValue
us-gaap:FairValueByMeasurementFrequency

us-gaap:FinancingReceivableAllowanceForCreditLosses
us-gaap:FinancingReceivablePortfolioSegment
us-gaap:FinancingReceivablePortfolioSegment, wrb:CumulativeEffectPeriodOfAdoption
wrb:CumulativeEffectPeriodOfAdoption

us-gaap:FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment

us-gaap:FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1

us-gaap:FinancingReceivableRecordedInvestmentNonaccrualStatus

us-gaap:HeldToMaturitySecurities
us-gaap:FinancialInstrument

us-gaap:HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
us-gaap:FinancialInstrument

us-gaap:HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment
us-gaap:FinancialInstrument

us-gaap:HeldToMaturitySecuritiesFairValue
us-gaap:FinancialInstrument

us-gaap:HeldToMaturitySecuritiesRestricted
us-gaap:FinancialInstrument
us-gaap:StatementBusinessSegments

us-gaap:IncomeTaxesReceivable
us-gaap:ConsolidatedEntities

us-gaap:Investments

us-gaap:JuniorSubordinatedNotes
us-gaap:ConsolidatedEntities

us-gaap:LiabilityForAsbestosAndEnvironmentalClaimsNet

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet
wrb:CumulativeEffectPeriodOfAdoption

us-gaap:LoansAndLeasesReceivableGrossCarryingAmount
us-gaap:ConsolidatedEntities
us-gaap:FinancingReceivablePortfolioSegment
us-gaap:FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable

us-gaap:LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest

us-gaap:LoansReceivableFairValueDisclosure
us-gaap:FairValueByMeasurementBasis
us-gaap:FinancingReceivablePortfolioSegment
us-gaap:FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable
us-gaap:FairValueByMeasurementBasis
us-gaap:LongTermDebtFairValue
us-gaap:DebtInstrument
us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo

us-gaap:MortgageLoansOnRealEstateCommercialAndConsumerNet

us-gaap:OperatingLeaseLiability

us-gaap:OtherAssets
us-gaap:ConsolidatedEntities

us-gaap:OtherLiabilities
us-gaap:ConsolidatedEntities

us-gaap:PreferredStockParOrStatedValuePerShare

us-gaap:PreferredStockSharesAuthorized

us-gaap:PreferredStockSharesIssued

us-gaap:PremiumsAndOtherReceivablesNet

us-gaap:PremiumsReceivableAllowanceForDoubtfulAccounts
wrb:CumulativeEffectPeriodOfAdoption

us-gaap:PrepaidReinsurancePremiums

us-gaap:RealEstateInvestmentPropertyAccumulatedDepreciation

us-gaap:RealEstateInvestmentPropertyNet

us-gaap:RealEstateInvestments

us-gaap:ReceivablesFromBrokersDealersAndClearingOrganizations

us-gaap:ReinsurancePayable

us-gaap:ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments

us-gaap:ReinsuranceRecoverables
us-gaap:CededCreditRisk

us-gaap:ReinsuranceRecoverablesAllowance
wrb:CumulativeEffectPeriodOfAdoption

us-gaap:ReinsuranceRecoverablesGross

us-gaap:ReinsuranceRecoverablesOnPaidAndUnpaidLosses
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments
us-gaap:ConsolidatedEntities
us-gaap:SeniorNotes
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber

us-gaap:ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet
us-gaap:ProductOrService
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented

us-gaap:StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
us-gaap:AdjustmentsForNewAccountingPronouncements, us-gaap:FinancialInstrument, us-gaap:StatementEquityComponents, wrb:CumulativeEffectPeriodOfAdoption
us-gaap:AdjustmentsForNewAccountingPronouncements, us-gaap:FinancialInstrument, wrb:CumulativeEffectPeriodOfAdoption
us-gaap:AdjustmentsForNewAccountingPronouncements, us-gaap:StatementEquityComponents, wrb:CumulativeEffectPeriodOfAdoption
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents, wrb:CumulativeEffectPeriodOfAdoption

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersDeferredPolicyAcquisitionCosts

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersReservesForUnpaidClaimsAndClaimsAdjustmentExpense

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersUnearnedPremiums

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

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

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

us-gaap:TaxCreditCarryforwardValuationAllowance

us-gaap:TradingLiabilities
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:TradingLiabilitiesFairValueDisclosure
us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByMeasurementFrequency

us-gaap:TradingSecurities
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByMeasurementFrequency

us-gaap:TreasuryStockShares

us-gaap:UnearnedPremiums
us-gaap:ValuationAllowancesAndReservesType
us-gaap:ValuationAllowancesAndReservesBalance

us-gaap:WorkersCompensationDiscountAmount
us-gaap:StatementBusinessSegments
us-gaap:ConsolidatedEntities
wrb:AccumulatedUndistributedNetIncomeOfSubsidiaries
us-gaap:FinancialInstrument, us-gaap:InvestmentSecondaryCategorization
wrb:AvailableForSaleEquitySecuritiesContinuousUnrealizedLossPositionAggregateLoss
us-gaap:InvestmentSecondaryCategorization

wrb:AvailableForSaleSecuritiesDebtSecuritiesFairValue
us-gaap:FinancialInstrument

wrb:AvailableForSaleSecuritiesDebtSecuritiesGrossUnrealizedGain
us-gaap:FinancialInstrument

wrb:AvailableForSaleSecuritiesDebtSecuritiesGrossUnrealizedLosses
us-gaap:FinancialInstrument

wrb:BuildingandLeaseObligations

wrb:DebtSecuritiesAllowanceforCreditLoss
us-gaap:AdjustmentsForNewAccountingPronouncements, wrb:CumulativeEffectPeriodOfAdoption

wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityAmortizedCost
us-gaap:ExternalCreditRatingByGrouping, us-gaap:FinancialInstrument
wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityContinuousUnrealizedLossPosition12MonthsorLonger
us-gaap:ExternalCreditRatingByGrouping, us-gaap:FinancialInstrument
wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss
us-gaap:FinancialInstrument
us-gaap:ExternalCreditRatingByGrouping, us-gaap:FinancialInstrument
wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityContinuousUnrealizedLossPositionLessthan12Months
us-gaap:ExternalCreditRatingByGrouping, us-gaap:FinancialInstrument
wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss
us-gaap:FinancialInstrument

wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityFairValue

wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityGrossUnrealizedGains

wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityGrossUnrealizedLosses
us-gaap:ExternalCreditRatingByGrouping, us-gaap:FinancialInstrument
wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityUnrealizedLossPosition
us-gaap:ExternalCreditRatingByGrouping, us-gaap:FinancialInstrument
wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityUnrealizedLossPositionAccumulatedLoss
us-gaap:FinancialInstrument
us-gaap:ExternalCreditRatingByGrouping, us-gaap:FinancialInstrument
wrb:DebtSecuritiesAvailableforsaleandHeldtomaturityUnrealizedLossPositionNumberofPositions
us-gaap:DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensation
wrb:DeferredCompensationArrangementwithIndividualUnitAwardsEarnedInPeriodValue
us-gaap:DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensation
wrb:DeferredCompensationArrangementwithIndividualUnitAwardsGrantedUnitsOutstanding
us-gaap:DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensation
wrb:DeferredCompensationArrangementwithIndividualUnitAwardsGrantedValue
us-gaap:FairValueByMeasurementBasis
wrb:DueFromBrokersFairValueDisclosure

wrb:DueToBroker

wrb:DueToBrokerFairValue
us-gaap:FairValueByMeasurementBasis

wrb:IncreaseDecreaseInEarnedUnbilledAuditPremiums

wrb:LiabilityforClaimsandClaimsAdjustmentExpenseNetOfReinsurance
us-gaap:StatementBusinessSegments
us-gaap:FairValueByMeasurementBasis
wrb:MarketableSecuritiesFairValueDisclosure

wrb:SeniorNotesAndOtherDebt
us-gaap:AwardType
wrb:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsUnearnedCompensationExpense

wrb:TaxCutsandJobsActIncompleteAccountingDeferredTaxLiabilitiesProvisionalUndistributedForeignEarnings
us-gaap:FairValueByMeasurementBasis
wrb:TradingAccountsReceivableFromBrokersFairValueDisclosure

wrb:WorkersCompensationDiscountAfterEffectsOfCededReinsuranceAmount

Tables

  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:CommonStockValue █████▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁70707070704747474747474747474747474747474747474747474747474747474747474747474747NA47NANA
us-gaap:CommonStockParOrStatedValuePerShare ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄0.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.2NA0.20.20.20.20.20.20.2200.00.2200.0200.0200.00.20.20.20.20.20.20.2NA0.2NANA
us-gaap:CommonStockSharesIssued █████▆▆▆▆▆▆▆▆▆▆▆▁▆▆▆1791831831831831211221211211211211211221211221220123127127NA126127127127132135135136028136135956137167138274137137140141141145148NA156NANA
us-gaap:CommonStockSharesOutstanding █████▆▆▆▆▆▆▆▆▆▆▆▁▆▆▆1791831831831831211221211211211211211221211221220123127127NA126127127127132135135136028136135956137167138274137137140141141145148NA156NANA
us-gaap:CommonStockSharesAuthorized ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄500500500500500500500500500500500500500500500500500500500500NA500500500500500500500500000500500000500000500000500500500500500500500NA500NANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding 190NA193193192NA128128128NA128128128NA128128128NA128129132NA133133135NA140141141NA141143143NA144147147NA154157NANANANA
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic 190NA190190190NA126126126NA125125121NA122122122NA123123125NA127127129NA135135136NA136138137NA138141141NA147151NANANANA
us-gaap:EarningsPerShareBasic ▁▃▄▅▅▅▆▇▆▆▆▄▅▆█▄▅▄▆▅▅▄▇▆▆▅▅▄▄▆▄▄▅▄▃▃▄▄▄▄▄▄▃▃-0.020.620.871.140.951.041.281.421.321.221.290.871.011.261.80.890.970.891.240.990.940.871.481.411.310.971.010.850.861.220.740.790.980.860.560.590.830.880.640.730.770.83999999999999990.610.61
us-gaap:EarningsPerShareDiluted ▁▄▄▆▅▅▆▇▆▆▆▄▅▆█▄▅▄▆▅▅▄▇▇▆▅▅▄▄▆▄▄▅▄▃▃▄▄▄▄▄▄▃▃-0.020.620.851.120.941.031.261.41.31.211.260.850.961.21.720.850.930.851.180.950.890.831.421.351.250.930.970.820.831.170.710.760.940.820.530.560.790.850.610.70.740.810.590.59
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:Revenues ▆█▇█▇▇▇▇▇▇█▇▇██▇▆▆▇▆▆▆▇▆▅▅▅▄▄▅▃▃▃▃▂▂▂▂▁▁▁▁▁▁18101976196520231937195119371910189119342031184818701971201918551807181118601789174417841840179617061696163415701506160814201415137813701279127012341231117611631153117611361155
 us-gaap:Revenues us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:InsuranceDomesticSegment▇█▇█▆██▇▇█▆▆▆▇▇▆▆▃▃▃▂▂▂▁▁1616163016051621154016251654158915871646153915411543159915711527150713131298127712251239124511711150NA107910611008NANA994NANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:ReinsuranceandMonolineExcessSegment244NANANA205NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetInvestmentIncome ▇▃▅█▅▅█▅▇▄▄▃▄▅▄▂▃▂▃▂▂▁▇▃▆174137161188158159186153174149142135148159145129130127133127124114179138168NA125143135NA116161157NA114149146133138128143141141132
 us-gaap:NetInvestmentIncome us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:InsuranceDomesticSegment▆▃▃▆▃▅█▅▇▅▄▃▄▆▅▃▄▂▂▂▁▁▆▃▅12397991321001221461141351151051021111321171001058993938281125103118NA9410797NANA120NANANANANANANANANANANANA
 us-gaap:NetInvestmentIncome us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:ReinsuranceandMonolineExcessSegment37NANANA39NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RealizedInvestmentGainsLosses -177NA17368NA2269485918340527717567-8532719207210952NANANA19NANANA47NANANA29335115204NA
us-gaap:OtherIncome █▁▁█▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁2002000000000000000000000NA000NA100NA0000000000
us-gaap:PolicyholderBenefitsAndClaimsIncurredNet █▇▆▆▅▆▆▅▄▅▇▄▅▅▅▄▃▃▄▃▃▃▃▂▁1107107210411028988102010179739639761081964979993965964922922926906900913887867822NA798805744NA736731679NA683674607591597570549543585597
us-gaap:InterestExpense ▅▃▇███▇▇▆▅▅▅▅▅▆▄▂▂▂▃▄▄▂▁▁36333840404039393736363636363734323131333434323030NA303131NA323228NA28282828262626252120
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest ▁▄▅▇▆▄▅▆▅▅▆▄▅▆█▄▅▄▆▅▅▄▇▇▆-6146202273229162209229210201226160184231331158174156228178168162278263247NA198158160NANA148NANANANANANANANANANANANA
 us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:StatementEquityComponents us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:AccumulatedOtherComprehensiveIncome50NA20-1NA0-3-9-50-43-39-44-5-41-13-260-3-12-17-21-19-6NA-41-19-17NANANANANANANANANANANANANANANA
us-gaap:IncomeTaxExpenseBenefit ▆▇▇▇▇▇▇▇▇▇▇▇▇▁█▇▇▇▇▇▇▇██▇-2263756472644484345635159-30211049544676555051898377NA604343NA323952NA20274448273541512727
 us-gaap:IncomeTaxExpenseBenefit us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:StatementEquityComponents us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss▇▆▆▆▆▆▆▆▆▄▄▄█▁█▇▆▅▆▆▆▅▅▅▆10-2000100-2-17-15-1315-411440-801-4-7-8-7-2NA-157-6NANANANANANANANANANANANANANANA
 us-gaap:IncomeTaxExpenseBenefit us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:StatementEquityComponents us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:AccumulatedOtherComprehensiveIncome█▅▅▅▅▆▅▅▅▁▂▂▂▅▂▄▅▆▅▅▄▄▄▄▅10-2000100-2-17-15-13-15-1-14-4020-1-4-6-7-6-2NA-146-5NANANANANANANANANANANANANANANA
us-gaap:NetIncomeLoss ▁▅▆█▇▅▆▇▆▆▆▅▅▆█▄▅▅▆▅▅▅▇▇▆▅▅▅▅▆▄▄▅▅▄▄▅▅▄▅▅▅▄▄-41191652161801321611801661541621091231522201081191091521231181101881791691301361151161651001081351177783116126931101181349797
 us-gaap:NetIncomeLoss us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:InsuranceDomesticSegment▄▆▆█▄▆█▅█▅▂▂▃▄▄▂▄▃▃▂▁▂▅▂▄140162162179145165178156181153123124134144144123139129130120114124154121138NA11810699NANA103NANANANANANANANANANANANA
 us-gaap:NetIncomeLoss us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:ReinsuranceandMonolineExcessSegment29NANANA35NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:Assets ████▇▇▇▆▆▆▆▆▆▆▅▅▅▄▄▄▄▄▅▄▃▃▃▃▃▃▃▃▂▂▂▂▁▁▁▁26089266432621826487255852489524855246212458724299243362399323547233642334523025222302173021738216892184721716220972116720704205512052320211201202015519932194621913318487183301819517983175281781217416NA17328NANA
 us-gaap:Assets us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:InsuranceDomesticSegment▇██▇▆▇▇▇▇▇▇▆▇▇▇▆▆▃▃▃▃▃▃▂▁▂▁▁19485200031977819444185911963419511192191932219263191361868718932191371897218475182321635116298161051601116065160741556515177152471509714849NA14661NANANANANANANANANANANANANANA
 us-gaap:Assets us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:ReinsuranceandMonolineExcessSegment▁█44054709NANANA4371NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:Liabilities ████▇▇▇▇▇▆▆▆▆▆▆▅▅▄▄▅▅▄▅▄▄▄▃▃▃▃▃▃▂▂▂▂▁▁▁▁20552205252011920467197821941619376191551909518848188651866718328182831838318086174421709717121171531723417092173541651216293161821612815945157101582015599152451499814471144611427514184138181397813728NA13726NANA
us-gaap:LiabilitiesAndStockholdersEquity ████▇▇▇▆▆▆▆▆▆▆▅▅▅▄▄▄▄▄▅▄▃▃▃▃▃▃▃▃▂▂▂▂▁▁▁▁26089266432621826487255852489524855246212458724299243362399323547233642334523025222302173021738216892184721716220972116720704205512052320211201202015519932194621913318487183301819517983175281781217416NA17328NANA
us-gaap:StockholdersEquity ▆███▇▆▆▆▆▆▆▆▅▅▅▅▄▄▄▃▄▄▄▄▃▃▃▃▃▃▃▃▂▂▂▂▁▁▁▁5493607460565976575954375437542654515411543052865179504749254902475146004583450245784589470846194375433643674238437843064324420741264008386239123791370238273682NA3596NANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:CashAndCashEquivalentsAtCarryingValue ▅▆▄▇▅▄▄▅▅▅▄▄▂▄▄▅▄▄▄▃▂▃█▄▃▄▅▃▅▅▇▅▆▅▄▄▂▃▅▄▁▂▃▄965102381212589378178199119569507737886087958739488377638797566146741342842643839966658945905118910121082911866794630642922781441515736771
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:PropertyPlantAndEquipmentNet ███▇▇█████▇█▅▅▅▅▅▅▄▄▄▄▄▄▅▅▄▃▂▂▂▂▂▂▂▁▁▁▁▁422422416398406416424427424422399424356349348346346348336332327332333335337339336291271267258264268262263254256254251245NA246NANA
 us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures us-gaap:ConsolidatedEntities srt:ParentCompanyNA7623NANANA6786NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:Goodwill ▇▇▇███▇████▅▅▅▅▆▆▆▆▆▆▆▂▂▃▃▃▃▃▁▁▁▁▁▁▁▁▁▃▃169169169173173173171178178178173144144144134154153153153150150150103103110110113112107878787909090909090107107NA107NANA
 us-gaap:IntangibleAssetsNetExcludingGoodwill us-gaap:BalanceSheetLocation us-gaap:OtherAssetsNA99NANANA104NANANA107NANANA82NANANA94NANANA96NANANA72NANANA31NANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
 us-gaap:LongTermDebt us-gaap:DebtInstrument wrb:SubsidiaryDebtNA108NANANA123NANANA12NANANA5NANANA81NANANA154NANANA77NANANA57NANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SeniorNotesDueAugust152019,us-gaap:SeniorNotesNA0NANANA140NANANA140NANANA140NANANA149NANANA149NANANA149NANANA149NANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SeniorNotesDueFebruary152037,us-gaap:SeniorNotesNA248NANANA248NANANA247NANANA247NANANA247NANANA247NANANA247NANANA247NANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SeniorNotesDueJanuary12022,us-gaap:SeniorNotesNA76NANANA76NANANA76NANANA76NANANA76NANANA76NANANA76NANANA75NANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SeniorNotesDueMaarch152022,us-gaap:SeniorNotesNA349NANANA348NANANA348NANANA347NANANA347NANANA346NANANA346NANANA346NANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SeniorNotesDueSeptember132020,us-gaap:SeniorNotesNA299NANANA299NANANA299NANANA298NANANA298NANANA298NANANA297NANANA297NANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SeniorNotesDueSeptember152019,us-gaap:SeniorNotesNA0NANANA299NANANA299NANANA299NANANA299NANANA298NANANA298NANANA298NANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SeniorNotesdueAugust12044,us-gaap:SeniorNotesNA345NANANA345NANANA345NANANA344NANANA344NANANA344NANANA0NANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SubordinatedDebenturedueApril302053,us-gaap:SubordinatedDebtNA341NANANA341NANANA340NANANA340NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SubordinatedDebenturedueJune12056,us-gaap:SubordinatedDebtNA281NANANA281NANANA281NANANA281NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SubordinatedDebenturedueMarch12056,us-gaap:SubordinatedDebtNA106NANANA106NANANA106NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SubordinatedDebtDueDecember302059,us-gaap:SubordinatedDebtNA290NANANA0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SubordinatedDebtDueMarch302058,us-gaap:SubordinatedDebtNA178NANANA178NANANA0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LongtermDebtType us-gaap:SubordinatedDebtNA1198NANANA907NANANA728NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LongtermDebtType wrb:SeniorNotesandOtherDebtNA1427NANANA1882NANANA1769NANANA1760NANANA1844NANANA2115NANANA1692NANANA1871NANANANANANANANANANANANANANA
us-gaap:MinorityInterest █████▇▇▇▇▇▇▇▇▆▇▇▇▆▆▆▆▆▆▆▆▆▅▅▆▅▂▂▁▁▁▁▁▁▁▁4443434342414139403940393833363636323334343434343433282732299987777666NA5NANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:StockholdersEquity ▆███▇▆▆▆▆▆▆▆▅▅▅▅▄▄▄▃▄▄▄▄▃▃▃▃▃▃▃▃▂▂▂▂▁▁▁▁5493607460565976575954375437542654515411543052865179504749254902475146004583450245784589470846194375433643674238437843064324420741264008386239123791370238273682NA3596NANA
us-gaap:CommonStockValue █████▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁70707070704747474747474747474747474747474747474747474747474747474747474747474747NA47NANA
us-gaap:RetainedEarningsAccumulatedDeficit █████▇▇▇▇▆▆▆▆▆▅▅▅▅▅▄▄▄▄▄▄▃▃▃▃▂▂▂▂▂▂▂▂▁▁▁7877793279717826772175587505742373226956688067356703659565196375628261786083594558365732576255875421526551485024492248174800471146154546443943724301419440773994NA3785NANA
us-gaap:TreasuryStockValue █▇▇▇▇▇▇▇▇▇▇▇▇▇▇▆▆▆▆▆▆▅▅▅▅▄▃▃▃▃▃▃▃▃▃▂▂▂▁▁2927272627082717272027202698270827152709269026862688268826582599260025632564257924552364235623232322213220061999196919691968191118671880188717711745175016271541NA1325NANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▁▃▃▃▂▂▂▂▃▅▆▆▅▅▅▅▅▄▅▅▆▆▇▇▆▆▆▆▇██▇▇▇▇▇▆▇▇▆-589-257-322-260-364-510-474-395-258681531336955-9578-662886152183273333258189217210428465508416393354335340263276396256NA163NANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:ConsolidatedEntities srt:ParentCompanyNA-257NANANA-510NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:NetCashProvidedByUsedInOperatingActivities ▄▇█▇▃▆▅▄▁▅▆▄▃▃█▅▄▆▆▆▂▄▇▃▄15234839232478277223139-201892971497512139419114026028727161160320111143NANANA115NANANA73NANANA556020412957150174NA
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▄▄▆▆▄▃▅▅▇▄▆▄▆▃▃▅▃▅█▆▁▄▇▅30-232-2542041-187-310-84-131100-20945-2697-372-323-105-341-1062715-589-17792-133NANANA143NANANA-278NANANA-75-184-133365-10-262-495NA
us-gaap:NetCashProvidedByUsedInFinancingActivities ▄▆▁▅▅▅▅▅▆▄▄▅▅▄▅▇▅▅▅▂▄▄█▅▄-22186-575-220-99-22-43157-107-108-15-2-191-9725427-7-28-409-109-222370-13-203NANANA-198NANANA366NANANA12-15460-149-116-106317NA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:NetCashProvidedByUsedInOperatingActivities ▄▇█▇▃▆▅▄▁▅▆▄▃▃█▅▄▆▆▆▂▄▇▃▄15234839232478277223139-201892971497512139419114026028727161160320111143NANANA115NANANA73NANANA556020412957150174NA
us-gaap:NetIncomeLoss ▁▅▆█▇▅▆▇▆▆▆▅▅▆█▄▅▅▆▅▅▅▇▇▆▅▅▅▅▆▄▄▅▅▄▄▅▅▄▅▅▅▄▄-41191652161801321611801661541621091231522201081191091521231181101881791691301361151161651001081351177783116126931101181349797
 us-gaap:NetIncomeLoss us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:InsuranceDomesticSegment▄▆▆█▄▆█▅█▅▂▂▃▄▄▂▄▃▃▂▁▂▅▂▄140162162179145165178156181153123124134144144123139129130120114124154121138NA11810699NANA103NANANANANANANANANANANANA
 us-gaap:NetIncomeLoss us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wrb:ReinsuranceandMonolineExcessSegment29NANANA35NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ProfitLoss ▁▅▆█▇▅▆▇▆▆▆▅▅▆█▄▅▅▆▅▅▅▇▇▆-3119165217181136164180167156162109124153220108120109152123118110188180169NA138115116NA101108135NA7783116126931101181349797
 us-gaap:ProfitLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:StatementEquityComponents us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss█▃▄▄▄▅▄▄▃▁▁▂▁▄▂▃▄▅▄▄▃▃▃▃▄39-920-140-2-7-32-28-25-28-3-26-8-140-2-8-13-16-14-4NA-28-14-13NANANANANANANANANANANANANANANA
 us-gaap:ProfitLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:StatementEquityComponents us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:AccumulatedOtherComprehensiveIncome█▃▄▄▄▅▄▄▃▁▁▂▁▄▂▃▄▅▄▄▃▃▃▃▄39-920-140-2-7-32-28-25-28-3-26-8-140-2-8-11-13-12-3NA-26-12-11NANANANANANANANANANANANANANANA
 us-gaap:ProfitLoss us-gaap:StatementEquityComponents us-gaap:NoncontrollingInterest▁▁▁▁▁█▆▁▃▃▁▁▃▁▁▁▁▁▁▁▁▁▁▁▁0000032011001000000000000NANANA0NANANANANANANA0000000NA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▄▄▆▆▄▃▅▅▇▄▆▄▆▃▃▅▃▅█▆▁▄▇▅30-232-2542041-187-310-84-131100-20945-2697-372-323-105-341-1062715-589-17792-133NANANA143NANANA-278NANANA-75-184-133365-10-262-495NA
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment NA58-973145151441-15771212168122316157118129NANANA13NANANA15NANANA111216910135NA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:NetCashProvidedByUsedInFinancingActivities ▄▆▁▅▅▅▅▅▆▄▄▅▅▄▅▇▅▅▅▂▄▄█▅▄-22186-575-220-99-22-43157-107-108-15-2-191-9725427-7-28-409-109-222370-13-203NANANA-198NANANA366NANANA12-15460-149-116-106317NA
us-gaap:PaymentsForRepurchaseOfCommonStock █▂▁▁▁▂▁▁▁▂▂▁▁▂▃▁▂▁▁▅▄▁▂▁█2021800017006192800326203705126912394192NANANA0NANANA0NANANA2315187135951150NA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
 us-gaap:DebtInstrumentInterestRateStatedPercentage us-gaap:DebtInstrument,us-gaap:LongtermDebtType wrb:SubordinatedDebtDueDecember302059,us-gaap:SubordinatedDebtNA0.051NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

Common Stock Value

us-gaap:CommonStockValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value7070707070474747474747474747474747474747474747474747474747474747474747474747474747
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.30.30.30.30.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.30.30.30.30.30.30.30.3

Common Stock Par Or Stated Value Per Share

us-gaap:CommonStockParOrStatedValuePerShare



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value0.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.2200.00.2200.0200.0200.00.20.20.20.20.20.20.20.2
Percentage of CommonStockParOrStatedValuePerShare100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Issued

us-gaap:CommonStockSharesIssued



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value1791831831831831211221211211211211211221211221220123127127126127127127132135135136028136135956137167138274137137140141141145148156
Percentage of CommonStockSharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Outstanding

us-gaap:CommonStockSharesOutstanding



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value1791831831831831211221211211211211211221211221220123127127126127127127132135135136028136135956137167138274137137140141141145148156161
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Authorized

us-gaap:CommonStockSharesAuthorized



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value500500500500500500500500500500500500500500500500500500500500500500500500500500500500000500500000500000500000500500500500500500500500
Percentage of CommonStockSharesAuthorized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value190193193192128128128128128128128128128128129132133133135140141141141143143144147147154157
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value190190190190126126126125125121122122122123123125127127129135135136136138137138141141147151
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType, us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:RestrictedStockUnitsRSU, us-gaap:TrustForBenefitOfEmployees



Period End2019-12-312018-12-312017-03-31
Value744
Percentage of WeightedAverageNumberOfSharesOutstandingBasic0.00.04.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-0.020.620.871.140.951.041.281.421.321.221.290.871.011.261.80.890.970.891.240.990.940.871.481.411.310.971.010.850.861.220.740.790.980.860.560.590.830.880.640.730.770.83999999999999990.610.61
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-0.020.620.851.120.941.031.261.41.31.211.260.850.961.21.720.850.930.851.180.950.890.831.421.351.250.930.970.820.831.170.710.760.940.820.530.560.790.850.610.70.740.810.590.59
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenues

us-gaap:Revenues



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value18101976196520231937195119371910189119342031184818701971201918551807181118601789174417841840179617061696163415701506160814201415137813701279127012341231117611631153117611361155
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value12613211212212210595
Percentage of Revenues7.06.75.66.36.35.55.1
Percentage of Revenues7.06.75.66.36.35.55.1
Percentage of Revenues srt:ConsolidationEliminations100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, wrb:InsuranceDomesticSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value1616163016051621154016251654158915871646153915411543159915711527150713131298127712251239124511711150107910611008994
Percentage of Revenues89.382.581.780.179.583.385.483.283.985.175.883.482.581.177.882.383.472.569.871.470.369.567.765.267.466.067.667.070.2
Percentage of Revenues89.382.581.780.179.583.385.483.283.985.175.883.482.581.177.882.383.472.569.871.470.369.567.765.267.466.067.667.070.2
Percentage of Revenues us-gaap:OperatingSegments wrb:InsuranceDomesticSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wrb:InsuranceInternationalSegment



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value168185179170176176183166168184187179200211201210217225213201200193183165
Percentage of Revenues9.39.48.88.89.19.29.78.29.19.89.39.611.111.311.312.012.212.311.911.812.312.312.211.7
Percentage of Revenues9.39.48.88.89.19.29.78.29.19.89.39.611.111.311.312.012.212.311.911.812.312.312.211.7
Percentage of Revenues us-gaap:OperatingSegments wrb:InsuranceInternationalSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wrb:ReinsuranceInternational



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value696562595155564950494850
Percentage of Revenues3.83.33.13.02.62.93.02.42.72.62.42.7
Percentage of Revenues3.83.33.13.02.62.93.02.42.72.62.42.7
Percentage of Revenues us-gaap:OperatingSegments wrb:ReinsuranceInternational100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wrb:ReinsuranceandMonolineExcessSegment



Period End2020-03-312019-03-31
Value244205
Percentage of Revenues13.510.6
Percentage of Revenues13.510.6
Percentage of Revenues us-gaap:OperatingSegments wrb:ReinsuranceandMonolineExcessSegment100.0100.0

Premiums Earned Net

Net Investment Income

us-gaap:NetInvestmentIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value174137161188158159186153174149142135148159145129130127133127124114179138168125143135116161157114149146133138128143141141132
Percentage of NetInvestmentIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues9.76.98.29.38.28.29.68.09.27.77.07.38.08.17.27.07.27.07.27.17.16.49.77.79.97.79.19.08.211.411.48.911.711.810.811.711.012.412.012.411.4

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value13181118151714
Percentage of NetInvestmentIncome7.811.36.111.88.611.38.0
Percentage of Revenues0.80.90.61.00.80.90.7
Percentage of Revenues srt:ConsolidationEliminations10.713.810.215.213.016.514.6

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, wrb:InsuranceDomesticSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value123979913210012214611413511510510211113211710010589939382811251031189410797120
Percentage of NetInvestmentIncome70.670.961.670.363.276.578.674.377.877.574.375.975.283.180.677.680.970.470.173.066.571.570.274.370.074.974.871.974.8
Percentage of Revenues6.84.95.16.55.26.37.66.07.26.05.25.66.06.75.85.45.85.05.05.24.74.66.85.76.95.86.86.58.5
Percentage of Revenues us-gaap:OperatingSegments wrb:InsuranceDomesticSegment7.66.06.28.26.57.58.87.28.67.06.96.77.38.37.56.67.06.87.27.36.76.610.18.810.38.710.19.712.1

us-gaap:OperatingSegments, wrb:ReinsuranceandMonolineExcessSegment



Period End2020-03-312019-03-31
Value3739
Percentage of NetInvestmentIncome21.625.0
Percentage of Revenues2.12.0
Percentage of Revenues us-gaap:OperatingSegments wrb:ReinsuranceandMonolineExcessSegment15.419.3

Realized Investment Gains Losses

us-gaap:RealizedInvestmentGainsLosses



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-177173682269485918340527717567-8532719207210952194729335115204
Percentage of RealizedInvestmentGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-9.80.13.63.51.23.62.63.19.12.22.83.98.70.30.4-0.52.91.51.11.23.96.13.11.33.42.42.80.41.00.51.70.4

Other Income

us-gaap:OtherIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value20020000000000000000000000001000000000000
Percentage of OtherIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues0.10.00.00.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.00.00.00.00.00.00.00.00.00.00.00.0

Policyholder Benefits And Claims Incurred Net

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value1107107210411028988102010179739639761081964979993965964922922926906900913887867822798805744736731679683674607591597570549543585597
Percentage of PolicyholderBenefitsAndClaimsIncurredNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues61.254.353.050.851.052.352.551.050.950.553.252.252.450.447.852.051.051.049.850.651.651.248.248.348.248.951.349.451.951.649.353.453.149.248.050.849.047.746.251.651.7

Deferred Policy Acquisition Cost Amortization Expense

Interest Expense

us-gaap:InterestExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value3633384040403939373636363636373432313133343432303030313132322828282828262626252120
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues2.01.72.02.02.12.12.12.12.01.91.82.02.01.91.81.91.81.81.71.82.01.91.81.71.81.92.02.12.32.32.12.22.22.32.32.32.22.32.21.91.7

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

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-6146202273229162209229210201226160184231331158174156228178168162278263247198158160148
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-0.47.410.313.511.88.310.812.011.210.411.18.79.911.816.48.59.78.612.310.09.79.115.114.714.512.110.110.610.5

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value5020-10-3-9-50-43-39-44-5-41-13-260-3-12-17-21-19-6-41-19-17
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest-774.01.40.1-0.80.3-1.7-4.5-24.9-19.1-24.6-24.1-2.4-12.4-8.3-1.24.10.4-1.7-7.6-10.8-7.7-7.4-2.4-20.7-12.1-10.8
Percentage of Revenues2.80.10.0-0.10.0-0.2-0.5-2.6-2.1-2.1-2.4-0.3-2.0-0.7-0.10.40.0-0.2-0.7-1.0-1.2-1.1-0.4-2.5-1.2-1.1
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-2263756472644484345635159-3021104954467655505189837760434332395220274448273541512727
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-0.21.41.92.82.51.42.32.52.32.33.12.83.2-15.35.52.73.02.64.13.12.92.94.94.64.63.72.82.92.32.83.81.62.13.64.02.33.13.64.42.52.4

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value10-2000100-2-17-15-1315-411440-801-4-7-8-7-2-157-6
Percentage of IncomeTaxExpenseBenefit-357.3-9.11.60.1-0.84.40.3-1.6-4.6-38.9-23.9-26.926.013.713.09.31.4-17.8-0.42.0-8.9-14.0-9.6-9.5-3.1-25.617.9-15.8
Percentage of Revenues0.6-0.10.00.0-0.00.10.0-0.0-0.1-0.9-0.7-0.70.8-2.10.70.20.0-0.5-0.00.1-0.3-0.4-0.5-0.4-0.1-0.90.5-0.5
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value10-2000100-2-17-15-13-15-1-14-4020-1-4-6-7-6-2-146-5
Percentage of IncomeTaxExpenseBenefit-357.3-9.11.60.1-0.84.40.3-1.6-4.6-38.9-23.9-26.9-26.00.6-13.0-9.3-1.44.90.4-2.0-8.9-11.9-8.4-8.2-2.7-24.015.7-13.6
Percentage of Revenues0.6-0.10.00.0-0.00.10.0-0.0-0.1-0.9-0.7-0.7-0.8-0.1-0.7-0.2-0.00.10.0-0.1-0.3-0.3-0.4-0.4-0.1-0.90.4-0.4
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Income Loss

us-gaap:NetIncomeLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-41191652161801321611801661541621091231522201081191091521231181101881791691301361151161651001081351177783116126931101181349797
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-0.26.08.410.79.36.88.49.48.88.08.05.96.67.810.95.96.66.18.26.96.86.210.210.09.97.78.47.47.710.37.17.79.88.66.06.59.410.38.09.510.311.48.68.4

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-33-37-62-55-45-47-65
Percentage of NetIncomeLoss764.0-22.5-28.8-30.5-28.3-26.6-39.2
Percentage of Revenues-1.9-1.9-3.1-2.8-2.4-2.5-3.4
Percentage of Revenues srt:ConsolidationEliminations-26.6-28.1-55.6-44.9-37.4-45.6-68.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, wrb:InsuranceDomesticSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value14016216217914516517815618115312312413414414412313912913012011412415412113811810699103
Percentage of NetIncomeLoss-3171.5136.098.782.780.8125.1110.386.7109.299.376.0114.2108.694.365.4113.6116.5117.785.598.097.1112.882.167.781.486.391.885.295.0
Percentage of Revenues7.78.28.38.97.58.59.28.29.67.96.16.77.27.37.16.77.77.17.06.76.67.08.46.88.17.26.86.67.3
Percentage of Revenues us-gaap:OperatingSegments wrb:InsuranceDomesticSegment8.710.010.211.19.510.210.89.811.49.38.08.18.79.09.28.19.29.810.09.49.410.112.410.412.011.010.09.910.4

us-gaap:OperatingSegments, wrb:ReinsuranceandMonolineExcessSegment



Period End2020-03-312019-03-31
Value2935
Percentage of NetIncomeLoss-660.619.7
Percentage of Revenues1.61.8
Percentage of Revenues us-gaap:OperatingSegments wrb:ReinsuranceandMonolineExcessSegment12.017.3

Assets

us-gaap:Assets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value2608926643262182648725585248952485524621245872429924336239932354723364233452302522230217302173821689218472171622097211672070420551205232021120120201551993219462191331848718330181951798317528178121741617328
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value88418335
Percentage of Assets33.233.5
Percentage of Assets33.233.5
Percentage of Assets srt:ParentCompany100.0100.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value219819131824246924812310
Percentage of Assets8.47.27.09.39.79.3
Percentage of Assets8.47.27.09.39.79.3
Percentage of Assets srt:ConsolidationEliminations100.0100.0100.0100.0100.0100.0

wrb:CorporateReconcilingItemsAndEliminations



Period End2019-12-312018-12-312017-12-312016-12-31
Value1930231018661702
Percentage of Assets7.29.37.77.3
Percentage of Assets7.29.37.77.3
Percentage of Assets wrb:CorporateReconcilingItemsAndEliminations100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, wrb:InsuranceDomesticSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value1948520003197781944418591196341951119219193221926319136186871893219137189721847518232163511629816105160111606516074155651517715247150971484914661
Percentage of Assets74.775.175.473.472.778.978.578.178.679.378.677.980.481.981.380.282.075.275.074.373.374.072.773.573.374.273.673.572.7
Percentage of Assets74.775.175.473.472.778.978.578.178.679.378.677.980.481.981.380.282.075.275.074.373.374.072.773.573.374.273.673.572.7
Percentage of Assets us-gaap:OperatingSegments wrb:InsuranceDomesticSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wrb:ReinsuranceandMonolineExcessSegment



Period End2020-03-312019-12-312018-12-31
Value440547094371
Percentage of Assets16.917.717.6
Percentage of Assets16.917.717.6
Percentage of Assets us-gaap:OperatingSegments wrb:ReinsuranceandMonolineExcessSegment100.0100.0100.0

Liabilities

us-gaap:Liabilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value2055220525201192046719782194161937619155190951884818865186671832818283183831808617442170971712117153172341709217354165121629316182161281594515710158201559915245149981447114461142751418413818139781372813726
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets78.877.076.777.377.378.078.077.877.777.677.577.877.878.378.778.578.578.778.879.178.978.778.578.078.778.778.678.978.178.578.378.378.478.378.978.578.978.878.578.879.2

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value27662897
Percentage of Liabilities13.514.9
Percentage of Assets10.411.6
Percentage of Assets srt:ParentCompany31.334.8

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value2608926643262182648725585248952485524621245872429924336239932354723364233452302522230217302173821689218472171622097211672070420551205232021120120201551993219462191331848718330181951798317528178121741617328
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value88418335
Percentage of LiabilitiesAndStockholdersEquity33.233.5
Percentage of Assets33.233.5
Percentage of Assets srt:ParentCompany100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value54936074605659765759543754375426545154115430528651795047492549024751460045834502457845894708461943754336436742384378430643244207412640083862391237913702382736823596
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets21.122.823.122.622.521.821.922.022.222.322.322.022.021.621.121.321.421.221.120.821.021.121.321.821.121.121.321.021.821.421.721.621.621.721.121.521.121.121.521.120.8

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value60745437
Percentage of StockholdersEquity100.0100.0
Percentage of Assets22.821.8
Percentage of Assets srt:ParentCompany68.765.2

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302008-12-312007-12-31
Value9651023812125893781781991195695077378860879587394883776387975661467413428426438399666589459051189101210829118667946306429227814415157367711134951
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.73.83.14.73.73.33.33.73.93.93.23.32.63.43.74.13.83.54.03.52.83.16.14.03.14.14.73.34.74.56.05.25.74.94.74.43.53.75.24.50.03.00.00.00.00.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-312017-12-312011-12-30
Value3898345124
Percentage of CashAndCashEquivalentsAtCarryingValue38.110.34.70.0
Percentage of Assets1.50.30.20.0
Percentage of Assets srt:ParentCompany4.41.00.00.0

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value422422416398406416424427424422399424356349348346346348336332327332333335337339336291271267258264268262263254256254251245246
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.61.61.61.51.61.71.71.71.71.71.61.81.51.51.51.51.61.61.51.51.51.51.51.61.61.71.61.41.31.31.31.41.41.41.41.41.41.51.41.41.4

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value1213
Percentage of PropertyPlantAndEquipmentNet2.93.2
Percentage of Assets0.00.1
Percentage of Assets srt:ParentCompany0.10.2

Investments In Affiliates Subsidiaries Associates And Joint Ventures

us-gaap:ConsolidatedEntities

us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures

srt:ParentCompany



Period End2019-12-312018-12-31
Value76236786
Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures100.0100.0
Percentage of Assets28.627.3
Percentage of Assets srt:ParentCompany86.281.4

Goodwill

us-gaap:Goodwill



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value169169169173173173171178178178173144144144134154153153153150150150103103110110113112107878787909090909090107107107
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.60.60.70.70.70.70.70.70.70.70.60.60.60.60.70.70.70.70.70.70.70.50.50.50.50.60.60.50.40.40.50.50.50.50.50.50.50.60.60.6

Intangible Assets Net Excluding Goodwill

us-gaap:BalanceSheetLocation

us-gaap:IntangibleAssetsNetExcludingGoodwill

us-gaap:OtherAssets



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value991041078294967231
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.40.40.40.40.40.40.2
Percentage of Assets us-gaap:OtherAssets0.00.00.00.00.00.00.00.0

Deferred Tax Assets Liabilities Net

Taxes Payable Current

Accrued Income Taxes Current

Long Term Debt

us-gaap:DebtInstrument

us-gaap:LongTermDebt

wrb:SubsidiaryDebt



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value108123125811547757
Percentage of LongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.50.10.00.40.70.40.3
Percentage of Assets wrb:SubsidiaryDebt0.00.00.00.00.00.00.00.0

us-gaap:DebtInstrument, us-gaap:LongtermDebtType

wrb:SeniorNotesDueAugust152019, us-gaap:SeniorNotes



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value0140140140149149149149
Percentage of LongTermDebt0.0113.41122.02526.1182.996.8193.3257.9
Percentage of Assets0.00.60.60.60.70.70.70.7
Percentage of Assets wrb:SeniorNotesDueAugust152019 us-gaap:SeniorNotes0.00.00.00.00.00.00.00.0

wrb:SeniorNotesDueFebruary152037, us-gaap:SeniorNotes



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value248248247247247247247247
Percentage of LongTermDebt228.0200.01980.64461.4303.0160.5320.7428.0
Percentage of Assets0.91.01.01.11.11.11.21.2
Percentage of Assets wrb:SeniorNotesDueFebruary152037 us-gaap:SeniorNotes0.00.00.00.00.00.00.00.0

wrb:SeniorNotesDueJanuary12022, us-gaap:SeniorNotes



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value7676767676767675
Percentage of LongTermDebt70.261.5608.91371.193.149.398.5131.4
Percentage of Assets0.30.30.30.30.40.40.40.4
Percentage of Assets wrb:SeniorNotesDueJanuary12022 us-gaap:SeniorNotes0.00.00.00.00.00.00.00.0

wrb:SeniorNotesDueMaarch152022, us-gaap:SeniorNotes



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value349348348347347346346346
Percentage of LongTermDebt320.8281.22782.56262.8425.0225.0449.1598.9
Percentage of Assets1.31.41.41.51.61.61.71.7
Percentage of Assets wrb:SeniorNotesDueMaarch152022 us-gaap:SeniorNotes0.00.00.00.00.00.00.00.0

wrb:SeniorNotesDueSeptember132020, us-gaap:SeniorNotes



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value299299299298298298297297
Percentage of LongTermDebt275.5241.52389.65379.0365.0193.3385.8514.6
Percentage of Assets1.11.21.21.31.41.41.41.5
Percentage of Assets wrb:SeniorNotesDueSeptember132020 us-gaap:SeniorNotes0.00.00.00.00.00.00.00.0

wrb:SeniorNotesDueSeptember152019, us-gaap:SeniorNotes



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value0299299299299298298298
Percentage of LongTermDebt0.0241.82393.45389.1365.8193.7386.9516.1
Percentage of Assets0.01.21.21.31.41.41.51.5
Percentage of Assets wrb:SeniorNotesDueSeptember152019 us-gaap:SeniorNotes0.00.00.00.00.00.00.00.0

wrb:SeniorNotesdueAugust12044, us-gaap:SeniorNotes



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value3453453453443443440
Percentage of LongTermDebt317.5278.52757.36210.2421.7223.40.0
Percentage of Assets1.31.41.41.51.61.60.0
Percentage of Assets wrb:SeniorNotesdueAugust12044 us-gaap:SeniorNotes0.00.00.00.00.00.00.0

wrb:SubordinatedDebenturedueApril302053, us-gaap:SubordinatedDebt



Period End2019-12-312018-12-312017-12-312016-12-31
Value341341340340
Percentage of LongTermDebt313.7275.12723.26132.1
Percentage of Assets1.31.41.41.5
Percentage of Assets wrb:SubordinatedDebenturedueApril302053 us-gaap:SubordinatedDebt0.00.00.00.0

wrb:SubordinatedDebenturedueJune12056, us-gaap:SubordinatedDebt



Period End2019-12-312018-12-312017-12-312016-12-31
Value281281281281
Percentage of LongTermDebt259.0227.12247.75061.2
Percentage of Assets1.11.11.21.2
Percentage of Assets wrb:SubordinatedDebenturedueJune12056 us-gaap:SubordinatedDebt0.00.00.00.0

wrb:SubordinatedDebenturedueMarch12056, us-gaap:SubordinatedDebt



Period End2019-12-312018-12-312017-12-31
Value106106106
Percentage of LongTermDebt97.785.6847.4
Percentage of Assets0.40.40.4
Percentage of Assets wrb:SubordinatedDebenturedueMarch12056 us-gaap:SubordinatedDebt0.00.00.0

wrb:SubordinatedDebtDueDecember302059, us-gaap:SubordinatedDebt



Period End2019-12-312018-12-31
Value2900
Percentage of LongTermDebt267.00.0
Percentage of Assets1.10.0
Percentage of Assets wrb:SubordinatedDebtDueDecember302059 us-gaap:SubordinatedDebt0.00.0

wrb:SubordinatedDebtDueMarch302058, us-gaap:SubordinatedDebt



Period End2019-12-312018-12-312017-12-31
Value1781780
Percentage of LongTermDebt164.4144.10.0
Percentage of Assets0.70.70.0
Percentage of Assets wrb:SubordinatedDebtDueMarch302058 us-gaap:SubordinatedDebt0.00.00.0

us-gaap:LongtermDebtType

us-gaap:SubordinatedDebt



Period End2019-12-312018-12-312017-12-31
Value1198907728
Percentage of LongTermDebt1101.7731.95818.3
Percentage of Assets4.53.63.0
Percentage of Assets us-gaap:SubordinatedDebt0.00.00.0

wrb:SeniorNotesandOtherDebt



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value14271882176917601844211516921871
Percentage of LongTermDebt1312.01517.914134.331699.62256.41371.72193.03238.2
Percentage of Assets5.47.67.37.58.59.78.29.3
Percentage of Assets wrb:SeniorNotesandOtherDebt0.00.00.00.00.00.00.00.0

Minority Interest

us-gaap:MinorityInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value44434343424141394039403938333636363233343434343434332827322999877776665
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.20.20.20.20.20.20.20.20.20.20.20.20.10.20.20.20.20.20.20.20.20.20.20.20.20.10.10.20.10.00.00.00.00.00.00.00.00.00.00.0

Stockholders Equity

us-gaap:StockholdersEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value54936074605659765759543754375426545154115430528651795047492549024751460045834502457845894708461943754336436742384378430643244207412640083862391237913702382736823596
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets21.122.823.122.622.521.821.922.022.222.322.322.022.021.621.121.321.421.221.120.821.021.121.321.821.121.121.321.021.821.421.721.621.621.721.121.521.121.121.521.120.8

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value60745437
Percentage of StockholdersEquity100.0100.0
Percentage of Assets22.821.8
Percentage of Assets srt:ParentCompany68.765.2

Common Stock Value

us-gaap:CommonStockValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value7070707070474747474747474747474747474747474747474747474747474747474747474747474747
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.30.30.30.30.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.30.30.30.30.30.30.30.3

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value78777932797178267721755875057423732269566880673567036595651963756282617860835945583657325762558754215265514850244922481748004711461545464439437243014194407739943785
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.229.830.429.530.230.430.230.129.828.628.328.128.528.227.927.728.328.428.027.426.726.426.126.426.225.625.124.924.523.924.124.224.124.624.224.023.923.922.922.921.8

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value79327558
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0
Percentage of Assets29.830.4
Percentage of Assets srt:ParentCompany89.790.7

Treasury Stock Value

us-gaap:TreasuryStockValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value29272726270827172720272026982708271527092690268626882688265825992600256325642579245523642356232323222132200619991969196919681911186718801887177117451750162715411325
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets11.210.210.310.310.610.910.911.011.011.111.111.211.411.511.411.311.711.811.811.911.210.910.711.011.210.49.89.99.89.89.99.89.810.210.39.79.710.09.18.97.7

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value27262720
Percentage of TreasuryStockValue100.0100.0
Percentage of Assets10.210.9
Percentage of Assets srt:ParentCompany30.832.6

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value-589-257-322-260-364-510-474-395-258681531336955-9578-662886152183273333258189217210428465508416393354335340263276396256163
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-2.3-1.0-1.2-1.0-1.4-2.1-1.9-1.6-1.10.30.60.60.30.2-0.00.20.0-0.30.10.40.70.81.21.61.30.91.11.02.12.32.52.12.11.91.81.91.51.62.21.50.9

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value-257-510
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0
Percentage of Assets-1.0-2.1
Percentage of Assets srt:ParentCompany-2.9-6.1

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value15234839232478277223139-20189297149751213941911402602872716116032011114311573556020412957150174
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues8.417.620.016.04.014.211.57.3-1.19.814.68.14.06.219.510.37.814.415.415.23.59.017.46.28.47.65.44.54.917.311.15.012.815.4

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value30-232-2542041-187-310-84-131100-20945-2697-372-323-105-341-1062715-589-17792-133143-278-75-184-133365-10-262-495
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues1.7-11.8-13.01.02.2-9.6-16.0-4.4-7.05.2-10.32.5-14.40.4-18.4-17.4-5.8-18.9-5.715.20.3-33.0-9.65.2-7.99.5-20.2-6.1-15.0-11.431.4-0.9-22.3-43.6

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-22186-575-220-99-22-43157-107-108-15-2-191-9725427-7-28-409-109-222370-13-203-19836612-15460-149-116-106317
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-12.34.4-29.3-1.1-0.1-5.1-1.2-2.38.3-5.6-5.4-0.9-0.1-9.7-4.813.71.5-0.4-1.5-22.9-6.3-12.520.1-0.8-11.9-13.226.61.0-12.55.2-12.8-10.1-9.027.9

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value15234839232478277223139-20189297149751213941911402602872716116032011114311573556020412957150174
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues8.417.620.016.04.014.211.57.3-1.19.814.68.14.06.219.510.37.814.415.415.23.59.017.46.28.47.65.44.54.917.311.15.012.815.4

Net Income Loss

us-gaap:NetIncomeLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-41191652161801321611801661541621091231522201081191091521231181101881791691301361151161651001081351177783116126931101181349797
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-0.26.08.410.79.36.88.49.48.88.08.05.96.67.810.95.96.66.18.26.96.86.210.210.09.97.78.47.47.710.37.17.79.88.66.06.59.410.38.09.510.311.48.68.4

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-33-37-62-55-45-47-65
Percentage of NetIncomeLoss764.0-22.5-28.8-30.5-28.3-26.6-39.2
Percentage of Revenues-1.9-1.9-3.1-2.8-2.4-2.5-3.4
Percentage of Revenues srt:ConsolidationEliminations-26.6-28.1-55.6-44.9-37.4-45.6-68.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, wrb:InsuranceDomesticSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value14016216217914516517815618115312312413414414412313912913012011412415412113811810699103
Percentage of NetIncomeLoss-3171.5136.098.782.780.8125.1110.386.7109.299.376.0114.2108.694.365.4113.6116.5117.785.598.097.1112.882.167.781.486.391.885.295.0
Percentage of Revenues7.78.28.38.97.58.59.28.29.67.96.16.77.27.37.16.77.77.17.06.76.67.08.46.88.17.26.86.67.3
Percentage of Revenues us-gaap:OperatingSegments wrb:InsuranceDomesticSegment8.710.010.211.19.510.210.89.811.49.38.08.18.79.09.28.19.29.810.09.49.410.112.410.412.011.010.09.910.4

us-gaap:OperatingSegments, wrb:ReinsuranceandMonolineExcessSegment



Period End2020-03-312019-03-31
Value2935
Percentage of NetIncomeLoss-660.619.7
Percentage of Revenues1.61.8
Percentage of Revenues us-gaap:OperatingSegments wrb:ReinsuranceandMonolineExcessSegment12.017.3

Profit Loss

us-gaap:ProfitLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-31191652171811361641801671561621091241532201081201091521231181101881801691381151161011081357783116126931101181349797
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value39-920-140-2-7-32-28-25-28-3-26-8-140-2-8-13-16-14-4-28-14-13
Percentage of ProfitLoss-1121.7-7.71.40.1-0.83.20.3-1.7-4.5-20.9-17.3-23.5-23.1-2.3-12.1-7.8-1.23.80.4-1.6-7.0-12.1-8.5-8.1-2.7-20.7-12.3-11.3

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value39-920-140-2-7-32-28-25-28-3-26-8-140-2-8-11-13-12-3-26-12-11
Percentage of ProfitLoss-1121.7-7.71.40.1-0.83.20.3-1.7-4.5-20.9-17.3-23.5-23.1-2.3-12.1-7.8-1.23.80.4-1.6-7.0-10.3-7.4-7.0-2.3-19.3-10.7-9.7

us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value000003201100100000000000000000000
Percentage of ProfitLoss-25.30.4-0.00.30.52.91.50.40.71.10.50.51.00.60.0-0.10.60.10.10.00.10.20.10.10.0-0.00.00.00.10.00.1-0.10.1

us-gaap:RetainedEarnings



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-41191652161801321611801661541621091231522201081191091521231181101881791691161351161269311011813497
Percentage of ProfitLoss125.399.6100.099.799.597.198.599.699.398.999.599.599.099.4100.0100.199.499.999.9100.099.999.899.999.9100.0100.0100.1100.0100.099.9100.099.9100.199.9

Increase Decrease In Other Operating Capital Net

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value30-232-2542041-187-310-84-131100-20945-2697-372-323-105-341-1062715-589-17792-133143-278-75-184-133365-10-262-495
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues1.7-11.8-13.01.02.2-9.6-16.0-4.4-7.05.2-10.32.5-14.40.4-18.4-17.4-5.8-18.9-5.715.20.3-33.0-9.65.2-7.99.5-20.2-6.1-15.0-11.431.4-0.9-22.3-43.6

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value58-973145151441-157712121681223161571181291315111216910135
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-22186-575-220-99-22-43157-107-108-15-2-191-9725427-7-28-409-109-222370-13-203-19836612-15460-149-116-106317
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-12.34.4-29.3-1.1-0.1-5.1-1.2-2.38.3-5.6-5.4-0.9-0.1-9.7-4.813.71.5-0.4-1.5-22.9-6.3-12.520.1-0.8-11.9-13.226.61.0-12.55.2-12.8-10.1-9.027.9

Proceeds From Issuance Of Long Term Debt

Repayments Of Long Term Debt

Payments For Repurchase Of Common Stock

us-gaap:PaymentsForRepurchaseOfCommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value2021800017006192800326203705126912394192002315187135951150
Percentage of PaymentsForRepurchaseOfCommonStock100.0100.00.00.00.0100.00.00.0100.0100.0100.00.00.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.00.0

Repayments Of Long Term Debt

Debt Instrument Interest Rate Stated Percentage

us-gaap:DebtInstrument, us-gaap:LongtermDebtType

us-gaap:DebtInstrumentInterestRateStatedPercentage

wrb:SubordinatedDebtDueDecember302059, us-gaap:SubordinatedDebt



Period End2019-12-31
Value0.051
Percentage of DebtInstrumentInterestRateStatedPercentage100.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.0
Percentage of LongTermDebtAndCapitalLeaseObligations wrb:SubordinatedDebtDueDecember302059 us-gaap:SubordinatedDebt0.0

Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number

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

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod

us-gaap:RestrictedStockUnitsRSU



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value00000000085500099900099600011531000
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Share Based Compensation

us-gaap:ShareBasedCompensation



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value1110111214881098911101099889686776476776556
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Liabilities

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value39200036937031447100045122904470004316367-104447-69-31-1433014766546117190
Percentage of DeferredTaxAssetsNet100.00.00.00.0100.0100.0100.0100.0100.00.00.00.0100.0100.0100.00.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Valuation Allowance

us-gaap:DeferredTaxAssetsValuationAllowance



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value3335165410002
Percentage of DeferredTaxAssetsValuationAllowance100.0100.0100.0100.0100.0100.00.00.00.0100.0

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value184193194179185
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0

Cash And Cash Equivalents Period Increase Decrease

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value96510238121258937817819911956950
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value11121571478898991010978796878664
Percentage of AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AllocatedShareBasedCompensationExpenseNetOfTax



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-03-31
Value12111015899910119798788665
Percentage of AllocatedShareBasedCompensationExpenseNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssumedPremiumsEarned



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value228224209198188208177180188207202193208265216225218213217211203218216224225226217214186
Percentage of AssumedPremiumsEarned100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssumedPremiumsWritten



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value266213239206216192181162192180194160215193224230246204221207204219225191240251212231226181200191150193158159
Percentage of AssumedPremiumsWritten100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-58-445320119-91-456
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0

us-gaap:CededPremiumsEarned



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value366354330325318325310304296304313291251312277275259268261264256268261256243249236222202
Percentage of CededPremiumsEarned100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CededPremiumsWritten



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value385372343346336327303323314301302322289269261296291265251267276249253282279243276254218239198180187186134152
Percentage of CededPremiumsWritten100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStockDividendsPerShareCashPaid



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.110.860.110.610.10.429999999999999940.430.430.09
Percentage of CommonStockDividendsPerShareCashPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ComprehensiveIncomeNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-36118410332032696824353771821721372211531581941494578620128254239144-10279192131173721601036234175146106314218
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value000003201-100-1000000001000-1000000000000000
Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-360184103321327100854354711831731382191531581951594578620128255239145-10379192132173721601036234175147106314218
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded



Period End2020-03-31
Value18
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded100.0

us-gaap:FinancialInstrument

us-gaap:CorporateDebtSecurities



Period End2020-03-31
Value6
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded34.0

us-gaap:ForeignGovernmentDebtSecurities



Period End2020-03-31
Value12
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded66.0

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal



Period End2020-03-31
Value16
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal100.0

us-gaap:FinancialInstrument

us-gaap:CorporateDebtSecurities



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal0.0

us-gaap:ForeignGovernmentDebtSecurities



Period End2020-03-31
Value16
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal100.0

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold



Period End2020-03-31
Value3
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold100.0

us-gaap:FinancialInstrument

us-gaap:CorporateDebtSecurities



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold0.0

us-gaap:ForeignGovernmentDebtSecurities



Period End2020-03-31
Value3
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold100.0

us-gaap:DepreciationAndAmortization



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value2571-92327542027293433261816221630192323192512252520222218212120228
Percentage of DepreciationAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DirectPremiumsEarned



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value18291846179717731723173617351705167416881692166616131667164716091568159915751545152415521505144913811351130112401163
Percentage of DirectPremiumsEarned100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DirectPremiumsWritten



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value1964182018531883182916541746178517871598167917271721158516431708170915591601160316471485155315801565141514051400126712491201111410941076962953
Percentage of DirectPremiumsWritten100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:Dividends

us-gaap:RetainedEarnings



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value201572011118797979177717771576771514141414131401314121211991010999
Percentage of Dividends100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectOfExchangeRateOnCashAndCashEquivalents



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-209-8-10717-560-57010-150-1011-27-287-16-15-138-1-208-6-19-5-4-3-31
Percentage of EffectOfExchangeRateOnCashAndCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquityMethodInvestmentRealizedGainLossOnDisposal



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value30-2000000001240167-3-4007023-1050-1450101902101000
Percentage of EquityMethodInvestmentRealizedGainLossOnDisposal100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1

us-gaap:AssetBackedSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.0-28000.00.02000.00.00.0-4000.02000.01000.00.01000.01000.00.01000.01000.01000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.0100.00.0100.00.00.0100.0100.0100.00.0100.0100.00.0100.0100.0100.0

us-gaap:CommonStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0100000000000000000000000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.00.01342.90.09550.00.00.04525.0-13200.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:DebtSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.0-28000.00.02000.00.00.0-4000.02000.01000.00.01000.01000.00.01000.01000.0178000.04000.00.00.015000.0-2000.06000.031000.012000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.0100.00.0100.00.00.0100.0100.0100.00.0100.0100.00.0100.0100.017800.00.00.00.00.00.00.00.00.0

us-gaap:EquitySecurities, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0100000000000000000000000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.00.01382.10.09550.00.00.04500.0-13200.0-1100.00.00.00.00.01700.01700.01600.00.00.00.00.00.00.00.00.0

us-gaap:PreferredStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.0-22000.0-11000.0-9000.00.0150000.0-51000.01000.00.0-11000.019000.00.00.0-12000.017000.017000.016000.00.0-51000.010000.0-48000.0-25000.0-31000.09000.030000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.00.039.30.00.00.00.0-25.00.0-1100.00.00.00.00.01700.01700.01600.00.00.00.00.00.00.00.00.0

us-gaap:TradingAssetsExcludingDebtAndEquitySecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0-9000000000000000000030-1
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.032642.90.07900.00.00.0-275.0-2000.00.00.0-7800.00.00.0-1500.0-11500.0-4600.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value1-90000000000000000000300
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.034125.00.017550.00.00.04325.0-15100.0-1000.00.0-7700.0100.00.0300.0-9700.014800.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss

us-gaap:AssetBackedSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.015000.00.046000.00.00.042000.04000.02000.016000.06000.010000.03000.05000.07000.01000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.0100.00.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value010000000000000010-10000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.012046.70.00.00.00.00.0-850.02168.83950.0490.021266.7-1940.0-371.4-35500.00.00.00.00.00.00.00.00.0

us-gaap:DebtSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value00000000000000000000-2-100
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.0100.00.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.00.00.00.00.0

us-gaap:EquitySecurities, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0-1100000000000000010-10000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.00.012046.70.00.00.00.00.00.0-850.02168.83950.0490.021266.7-1940.0-371.4-35500.00.00.00.00.00.00.00.00.0

us-gaap:TradingAssetsExcludingDebtAndEquitySecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.00.00.00.00.00.00.00.00.0-78000.017000.061000.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.00.00.00.00.00.00.00.00.0-487.5283.3610.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value-1100000000000000010-1-2-100
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss0.012146.70.0100.00.00.0100.0100.0-750.01781.24333.31200.021366.7-1840.0-271.4-35400.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases

us-gaap:AssetBackedSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.00.00.00.0-10000.010000.00.00.00.00.00.00.00.00.00.00.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases0.00.00.00.0100.0100.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value00000000000000000000001100
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases0.00.00.00.00.0-0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:DebtSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.00.00.00.0-10000.010000.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0154000.00.042000.042000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases0.00.00.00.0100.0100.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:EquitySecurities, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value00200000060000000000001400
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases0.00.00.00.00.0-0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PreferredStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value002000006000000000000300
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TradingAssetsExcludingDebtAndEquitySecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value00140700300000000000720220
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases0.00.00.00.0-76410.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value021407003600000000007201720
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases0.00.00.00.0-76310.0100.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales

us-gaap:AssetBackedSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.012000.00.0122000.0-8000.010000.0100000.015000.0-91000.015000.043000.0-15000.00.00.00.00.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales0.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0

us-gaap:CommonStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value1010000000000000000000000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales0.00.012900.00.00.0-2837.50.00.00.0-0.00.00.0-0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:DebtSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value000000000000000000000904
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales0.0100.00.0100.0100.0100.0100.0100.0-5.5100.030.2-100.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:EquitySecurities, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value1010006000000000000000300
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales0.00.012900.00.00.0-2837.569980.00.00.0-0.00.00.0-0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PreferredStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0000006000000000000000300
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales0.00.00.00.00.0-0.069980.00.00.0-0.00.00.0-0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TradingAssetsExcludingDebtAndEquitySecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value017317000000000000007100490
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales0.0143008.30.014250.8-0.00.011.00.0-0.053.30.0-0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value01831707000000000000710018104
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales0.0156008.30.014350.8-2737.570080.0111.0100.0-5.5153.330.2-100.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements

us-gaap:AssetBackedSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.00.00.00.00.00.00.00.00.00.00.00.0-5000.0-9000.0-17000.0-4000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements0.00.00.00.00.00.00.00.00.00.00.00.0100.0100.0100.0100.0

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3

us-gaap:CommonStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value0.00.0-1000.01000.01000.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel30.00.0100.0100.0100.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:EquitySecurities, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value0.00.0-1000.01000.01000.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel30.00.0100.0100.0100.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings

us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302015-12-312015-09-302015-06-302015-03-312014-12-31
Value0-900000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings0.0100.00.00.00.00.0100.0

us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySales

us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302015-12-312015-09-302015-06-302015-03-312014-12-31
Value0500000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySales0.0100.00.00.00.00.0100.0

us-gaap:FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-30
Value-200-1000000000000000000000000-7060000
Percentage of FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease100.00.0100.0100.00.00.00.00.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:GainLossOnInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-177-22173681422694859183405277175675327191922244721222933511520433
Percentage of GainLossOnInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnSaleOfOtherInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-18-10100010014131137-10-2-30700000000
Percentage of GainLossOnSaleOfOtherInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0100.0100.0100.0100.0

us-gaap:GainLossOnSalesOfLoansNet



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value0000002000
Percentage of GainLossOnSalesOfLoansNet0.00.00.0100.0100.0100.0100.00.00.00.0

us-gaap:IncomeLossFromEquityMethodInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312010-12-312010-09-302010-06-302009-12-312009-09-302009-06-30
Value40-81946111541534017503526382518161122216-3592253104-1914-25-37
Percentage of IncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentType

us-gaap:RealEstateFunds



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value6142101114352614301941710
Percentage of IncomeLossFromEquityMethodInvestments16.7-23.222.15.691.874.734.767.564.682.760.454.917.044.742.0

wrb:EnergyFunds



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value4-7-3-3-301-10-12-83
Percentage of IncomeLossFromEquityMethodInvestments10.996.3-17.0-7.9-29.81.64.1-2.40.2-25.2-24.312.2

wrb:FinancialServicesFunds



Period End2020-03-312019-12-312019-03-312018-12-31
Value15-712
Percentage of IncomeLossFromEquityMethodInvestments37.592.813.418.6

wrb:OtherFunds



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value113-30474325181463224186576
Percentage of IncomeLossFromEquityMethodInvestments28.4-41.6-161.1102.338.023.861.334.935.334.564.769.467.616.523.138.938.3

wrb:TransportationFunds



Period End2020-03-312019-12-312019-03-312018-12-31
Value2184
Percentage of IncomeLossFromEquityMethodInvestments6.5-24.475.427.0

us-gaap:IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value40-8194611154112401716826382518161122216-186625581027134-8-19-33-26
Percentage of IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeTaxesPaidNet



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value04482062111037143112815424948514472337
Percentage of IncomeTaxesPaidNet0.0100.0100.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInBrokerDealerRelatedReceivablesPayablesNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value3451-35-412214111-584464-1262281-5117-6966-25-20235-4023-51-43-16-74560-671257-56
Percentage of IncreaseDecreaseInBrokerDealerRelatedReceivablesPayablesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value12-231933-36-256089-501-2793-5079-8038-4633-31-4-44-19-362-70-22130-44-525-391610
Percentage of IncreaseDecreaseInDeferredIncomeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredPolicyAcquisitionCosts



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value26-106517-15-346-25-6-36-2511733-1051221-112724231122-51613-198
Percentage of IncreaseDecreaseInDeferredPolicyAcquisitionCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value200168922311191081063120153209110-1012200131108-76077132152-654104
Percentage of IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-204-18946-1545537102-24398-13159-1771114472-181842372-24385640-190-148-36-97924251-12810087
Percentage of IncreaseDecreaseInOtherOperatingLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInPremiumsReceivable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value97-17-1667156-63-457874-44-4710059-31-829579-38-336271-21-71979976978819-473335-34-36
Percentage of IncreaseDecreaseInPremiumsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInReinsuranceRecoverable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value4349392205037-23100247732-6780547426-301144646-13-49493416102-3382-41027
Percentage of IncreaseDecreaseInReinsuranceRecoverable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInTradingSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-265774680204-25220338-752-14120-42129-113-26266-70-8
Percentage of IncreaseDecreaseInTradingSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInUnearnedPremiums



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value163-3582118135-92554116-117-1826113-119-7105171-552456117-674798198174115152-69191636-11419
Percentage of IncreaseDecreaseInUnearnedPremiums100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInUnearnedPremiumsNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-15456-73-96-11699-20-43-97112104-76110-21-82-13644-39-50-10346-64-72-162-94-59-144-43
Percentage of IncreaseDecreaseInUnearnedPremiumsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InsuranceCommissionsAndFees



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value2521232225263029303433333329323640313535363526262826272626272322252221222021192225
Percentage of InsuranceCommissionsAndFees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestPaid



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value54681462641061106110611260756556115611481148534544
Percentage of InterestPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentIncomeInterestAndDividend



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value177139162189159161187154176151144137150160147132132130135130127116180142171127145137117162158114150146119130
Percentage of InvestmentIncomeInterestAndDividend100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentType

us-gaap:EquityMethodInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value40-8194611154112401715826382518161122216-35922535221035
Percentage of InvestmentIncomeInterestAndDividend22.9-5.811.724.77.19.521.98.222.911.510.56.517.724.217.113.912.68.716.916.84.8-3.132.715.731.44.315.57.921.9

us-gaap:EquitySecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value11111110000000110111111213323
Percentage of InvestmentIncomeInterestAndDividend0.91.00.90.70.80.60.50.40.40.30.40.40.40.50.71.00.70.90.80.90.91.10.81.51.12.52.51.62.4

us-gaap:RealEstate



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value66754353655542012242213333333
Percentage of InvestmentIncomeInterestAndDividend3.44.84.92.72.72.03.02.13.73.43.53.93.01.60.40.92.11.63.21.62.20.91.72.21.82.42.12.32.1

wrb:ArbitrageTradingAccount



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value1887107785245656335208906511430
Percentage of InvestmentIncomeInterestAndDividend0.66.05.23.86.64.34.15.42.91.93.14.04.23.64.42.52.44.21.9-0.17.18.50.04.93.29.23.42.70.0

wrb:FixedMaturitySecuritiesCashCashEquivalentsandLoansReceivable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value128130125128132134131129123125118116112112114108108110104105108107117107106104111117119
Percentage of InvestmentIncomeInterestAndDividend72.293.977.468.182.783.570.584.070.082.882.585.274.670.177.481.782.384.777.280.785.192.564.975.862.481.676.485.473.7

us-gaap:InvestmentIncomeInvestmentExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value221111001111111322222113211211101001
Percentage of InvestmentIncomeInvestmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value8421721925229536628120511139931221797439132220259
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value864765707633567593578716810565564659773470742632555
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1107107210411028988102010179739639761081964979993965964922
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MarketableSecuritiesGainLoss



Period End2020-03-312019-03-31
Value-17768
Percentage of MarketableSecuritiesGainLoss100.0100.0

us-gaap:MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-143173682269481834052175625662719721095243331924
Percentage of MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value5020-10-3-9-50-43-39-44-5-41-13-260-3-12-20-24-22-6-43-21-20
Percentage of MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments-34.9196.90.3-2.52.7-5.5-19.80.0-23.5-97.8-84.70.0-23.4-207.5-8.40.01.3-11.2-67.10.0-34.1-20.6-13.1-100.1-66.3-100.5

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value00000320110010000000000001000000000000000
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance

us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-03-31
Value00000-100030030000012
Percentage of NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingCostsAndExpenses



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value181718291762174917071788172816811680173318051687168617391688169716321654163216111575162115621533145914351412134612861267119111821160107310551054101799299010101029
Percentage of OperatingCostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingLeaseCost



Period End2020-03-312019-09-302019-06-302019-03-31
Value11101011
Percentage of OperatingLeaseCost100.0100.0100.0100.0

us-gaap:OperatingLeasePayments



Period End2020-03-312019-09-302019-06-302019-03-31
Value10111111
Percentage of OperatingLeasePayments100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToNoncontrollingInterest

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value1000.0-2000.0123000.030000.0-47000.0-132000.060000.037000.0-11000.00.033000.0-33000.019000.0-125000.057000.0-5000.014000.0-68000.094000.0-10000.022000.086000.0-82000.0-19000.0-18000.0-9000.035000.0-40000.0
Percentage of OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value1000.0-2000.0123000.030000.0-47000.0-132000.060000.037000.0-11000.00.033000.0-33000.019000.0-125000.057000.0-5000.014000.0-68000.094000.0-10000.022000.086000.0-82000.0-19000.0-18000.0-9000.035000.0-40000.0
Percentage of OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-332-25-28147169-4-96-40-160-9180-72156114-57-7-15124-90-2576112-59-30312
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:DebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-326-37-121461740-100-36-159
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax98.1144.042.699.7103.10.4103.891.099.3

us-gaap:EquityMethodInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-719-160-5-43-3-1
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax2.3-74.958.80.2-3.199.9-3.89.00.7

us-gaap:OtherDebtSecurities



Period End2020-03-312019-03-31
Value0-6
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax0.1-4.1

wrb:DebtSecuritiesPreviouslyImpaired



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value100000000
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax-0.50.1-1.30.1-0.03.00.00.0-0.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value-332-28147169-96-40-160-868-9-72156
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value-258-24118125-94-32-125-843-8-47105
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value-73-32843-1-8-350240-2451
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-2985-27118127-3-95-29-118-45196919115-2011378-503-9724-4536277-10-18220
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-39673-63103146-39-79-133-105-5248894269-405776-98-58-63-23-78-46877333-206-25
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax132.91365.5235.787.8115.51106.183.5454.889.2115.0243.2129.2213.759.6192.950.897.4194.3-1486.065.6-94.4174.4-1493.4139.594.8-329.1112.7-122.1

us-gaap:AccumulatedTranslationAdjustment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-9868-36-1419-3615-10412-6282022-46-19-55-2-48-6233-47-33-4924-444-23-46
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax32.91265.5135.7-12.215.51006.1-16.5354.8-10.815.0143.229.2113.7-40.492.9-49.2-2.694.3-1586.0-34.4-194.474.4-1593.439.5-5.2-429.112.7-222.1

us-gaap:OtherComprehensiveIncomeLossBeforeTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-43142-65132189-40-81-144-148-126208813133-91100112-105-70-118-23-121-71104109-12-323-31
Percentage of OtherComprehensiveIncomeLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax

us-gaap:AccumulatedTranslationAdjustment



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value-98-36-141915-10412282022-19-55
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-302012-03-31
Value-9868-36-1419-3615-10412-6282022-46-19-55-2-48-6233-47-33-4924-444-23-46-1715
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedTranslationAdjustment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-31
Value-9868-36-1419-3615-10412-6282022-46-19-55-2-48-6233-47-33-4924-4-4615
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-302012-03-31
Value-35764-61104145-35-79-136-112-8520631365-674974-94-58-65-31-90-6075697-218-362338
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-258-3-241181250-94-32-125-78-843-8112-4710576-464-9916-58-124872-38-1977
Percentage of OtherComprehensiveIncomeLossNetOfTax72.5-5.840.3113.986.4-2.1119.823.7111.391.9-40.068.3-63.5171.571.0213.6102.749.3-7.7151.0-51.765.021.464.2104.9-535.390.2-21.1

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-35764-61104145-35-79-136-112-8520631365-674974-94-58-65-31-90-6075697-218-36
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedTranslationAdjustment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-9868-36-1419-3615-10412-6282022-46-19-55-2-48-6233-47-33-4924-444-23-46
Percentage of OtherComprehensiveIncomeLossNetOfTax27.5105.859.7-13.913.6102.1-19.876.3-11.38.1140.031.7163.5-71.529.0-113.6-2.750.7107.7-51.0151.737.281.933.1-5.8610.310.6126.0

us-gaap:NoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-31
Value1000.0-2000.0123000.030000.0-47000.040000.0-60000.0-37000.011000.038000.0-33000.033000.0-19000.07000.0-57000.05000.0-14000.068000.0-94000.010000.0-22000.0-86000.082000.019000.018000.040000.023000.0
Percentage of OtherComprehensiveIncomeLossNetOfTax-0.0-0.0-0.20.0-0.0-0.10.10.0-0.0-0.0-0.20.1-0.10.00.10.0-0.0-0.10.2-0.00.10.1-0.10.00.0-0.10.1

us-gaap:OtherComprehensiveIncomeLossTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-73-21-32843-5-1-8-35-41024019724-51-37-1221252-88411-29-3919105-5
Percentage of OtherComprehensiveIncomeLossTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-258-3-241181250-94-32-125-78-843-8112-4710576-464-9916-58-124872-38-19777955533992-6-931257643-16220105
Percentage of OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-260-3-251181250-94-32-125-78-842-8113-4610376784-9916-58-1348720
Percentage of OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax100.699.3101.1100.0100.0100.599.999.9100.0100.0100.398.2100.9100.698.398.8100.1-168.4101.4100.0100.199.8101.699.799.5-0.5

us-gaap:OtherCostAndExpenseOperating



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value578601581591588601577593610615600616603625606581582591573573551563544534515504494481451448431405402384388369370367364353365
Percentage of OtherCostAndExpenseOperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-30
Value0000500000000001812000
Percentage of OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet0.00.00.00.0100.00.00.00.00.00.00.00.00.00.00.0100.0100.00.00.00.0

us-gaap:PaymentsForLossesAndLossAdjustmentExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value948983926885863960860922921964876877871910874853815
Percentage of PaymentsForLossesAndLossAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromLoansReceivable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-20-300-1-118-25-21-7-3-7-28-6-123-1326-21-41-21-312282295393-4-1-16-3-205
Percentage of PaymentsForProceedsFromLoansReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromOtherInvestingActivities



Period End2020-03-312019-03-31
Value-86000.00.0
Percentage of PaymentsForProceedsFromOtherInvestingActivities100.00.0

us-gaap:PaymentsOfDividendsCommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value2017811118015818601794771501530151414141413140131412009181101809
Percentage of PaymentsOfDividendsCommonStock100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.00.0100.0

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value259814991219110415281490112419772085141033651397176712602041120610321067121910731094119310649021131896
Percentage of PaymentsToAcquireAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value3510624635-1042441016007501251-829082-19291935682470922010463
Percentage of PaymentsToAcquireAvailableForSaleSecuritiesEquity100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired



Period End2019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312011-01-31
Value00006000071012-13540700080-1503801123
Percentage of PaymentsToAcquireBusinessesNetOfCashAcquired0.00.00.00.0100.00.00.0100.00.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:PaymentsToAcquireRealEstate



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value24-29586452593582336774961489193605371664044-39189283510558
Percentage of PaymentsToAcquireRealEstate100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PremiumsWrittenNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value1845166017491743170915191624162416651478157115641646151016071642166314991571154315751455152514891525142313411376127511901203112610571083918986961983828969908
Percentage of PremiumsWrittenNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromDivestitureOfBusinessesNetOfCashDivested



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-03-31
Value0.00.00.00.00.0171000.00.0
Percentage of ProceedsFromDivestitureOfBusinessesNetOfCashDivested0.00.00.00.00.0100.00.0

us-gaap:ProceedsFromIssuanceOfDebt



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302013-09-30
Value4000-119181000-2278110-130426-22
Percentage of ProceedsFromIssuanceOfDebt100.00.00.00.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value10556557878036867186511207976961972088809977364552711192879655718673667546667
Percentage of ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value00-15-40-13-2-10-2-20-1-20-431-31-100017100000000
Percentage of ProceedsFromPaymentsForOtherFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value157475121346973683687692004953101113497191365357334381622-283274668633184328463
Percentage of ProceedsFromSaleOfAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value5391137481651311525847375119108121-701393-210663832635814613644
Percentage of ProceedsFromSaleOfAvailableForSaleSecuritiesEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProvisionForLoanLossesExpensed



Period End2020-03-31
Value2
Percentage of ProvisionForLoanLossesExpensed100.0

us-gaap:FinancingReceivablePortfolioSegment

us-gaap:CommercialPortfolioSegment



Period End2020-03-31
Value1
Percentage of ProvisionForLoanLossesExpensed60.8

us-gaap:CommercialRealEstatePortfolioSegment



Period End2020-03-31
Value838000.0
Percentage of ProvisionForLoanLossesExpensed39.2

us-gaap:StatementEquityComponents

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-399-201-402-7197-28-25-2876-26-8-1150-2-883-16-14-4-28-14-13
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value-399-201-402-7197-28-25-2876-26-8-1150-2-872-13-12-3-26-12-11
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.086.587.486.286.993.687.286.2

us-gaap:ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value2352521722391732431861612381762471423520021316712612712313111815612889100186142110114109851348011488135
Percentage of ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value811976767371195168656619342031184818701971201918551807181118601789174417841840179617061696163415701506160814201415137813701279127012341231117611631153117611361155
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability



Period End2020-03-312019-09-302019-06-302019-03-31
Value12324
Percentage of RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised

us-gaap:TreasuryStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-30
Value1820106024
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueTreasuryStockReissued

us-gaap:TreasuryStock



Period End2019-12-312019-09-302019-06-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value10001200002400131002010002302028281591012
Percentage of StockIssuedDuringPeriodValueTreasuryStockReissued100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1097105010271008971100910019599569641072967958987960961916
Percentage of SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value417377-208712-367212-71131612
Percentage of SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:TreasuryStockValueAcquiredCostMethod

us-gaap:TreasuryStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value2021800017006192800326203705126918334192062315187135951150
Percentage of TreasuryStockValueAcquiredCostMethod100.0100.00.00.00.0100.00.00.0100.0100.0100.00.00.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:UnrealizedGainLossOnInvestments



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value-15446942-131-54-94000
Percentage of UnrealizedGainLossOnInvestments100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:WeightedAverageNumberOfSharesRestrictedStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value7007004004
Percentage of WeightedAverageNumberOfSharesRestrictedStock100.00.00.0100.00.00.0100.00.00.0100.0

us-gaap:StatementEquityComponents

wrb:AdjustmentstoAdditionalPaidinCapitalStockIssuedDuringPeriodValueStockOptionsExercisedValueRestrictedStockIssuedNetofTaxBenefitExpense

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value41282021150025000300-72301-10230
Percentage of AdjustmentstoAdditionalPaidinCapitalStockIssuedDuringPeriodValueStockOptionsExercisedValueRestrictedStockIssuedNetofTaxBenefitExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:AvailableforSaleandHeldtoMaturityRealizedGainsDebtSecuritiesExcludingOtherthanTemporaryImpairmentsandAllowances



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value413235327136875533102315134211312199105
Percentage of AvailableforSaleandHeldtoMaturityRealizedGainsDebtSecuritiesExcludingOtherthanTemporaryImpairmentsandAllowances100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:AvailableforSaleandHeldtoMaturityRealizedLossesDebtSecuritiesExcludingOtherthanTemporaryImpairmentsandAllowances



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value41433324310030112120102010551
Percentage of AvailableforSaleandHeldtoMaturityRealizedLossesDebtSecuritiesExcludingOtherthanTemporaryImpairmentsandAllowances100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:AvailableforsaleSecuritiesGrossRealizedGainLossEquitySecuritiesExcludingOtherthanTemporaryImpairments



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value000231491191224434324218400009-1923625181518
Percentage of AvailableforsaleSecuritiesGrossRealizedGainLossEquitySecuritiesExcludingOtherthanTemporaryImpairments0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:ChangeinUnrealizedGainlossonInvestmentsIncludingPortionAttributabletoNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-1000.02000.0-123000.0-30000.047000.0132000.0-60000.0-37000.011000.00.0-5000.05000.0-19000.07000.0-57000.05000.0-14000.068000.0-94000.010000.0-22000.0-86000.082000.019000.018000.09000.0-35000.040000.05000.0
Percentage of ChangeinUnrealizedGainlossonInvestmentsIncludingPortionAttributabletoNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:ChangeinUnrealizedGainlossonInvestmentsIncludingPortionAttributabletoNoncontrollingInterestNetofTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-258-3-241181250-94-32-125-78-843-8112-4710576-464-9916-58-124872-38-197739
Percentage of ChangeinUnrealizedGainlossonInvestmentsIncludingPortionAttributabletoNoncontrollingInterestNetofTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:ChangeinUnrealizedGainlossonInvestmentstax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-73-21-32843-5-2-8-35-41024060-245137-10-12-528-32-122839-16-103020
Percentage of ChangeinUnrealizedGainlossonInvestmentstax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:DebtSecuritiesAllowanceforCreditLossPeriodIncreaseDecrease



Period End2020-03-312019-03-31
Value-310
Percentage of DebtSecuritiesAllowanceforCreditLossPeriodIncreaseDecrease100.00.0

wrb:ExpensesFromWhollyOwnedInvestees



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value94122101889012693756910486686684781169510810098891099710191103818966545164555347604948564946
Percentage of ExpensesFromWhollyOwnedInvestees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementBusinessSegments

wrb:FavorableReserveDevelopmentNetOfPremiumOffsets

wrb:InsuranceDomesticSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value721798810166122326
Percentage of FavorableReserveDevelopmentNetOfPremiumOffsets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:IncomeBeforeIncomeTaxes



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value-620227322920922921022616018433115817415622817816816227826324719815816013314818797110160175121145160185125125
Percentage of IncomeBeforeIncomeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-41-47-78-68-54-59-81
Percentage of IncomeBeforeIncomeTaxes645.6-23.5-28.6-29.9-26.2-26.1-38.4

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, wrb:InsuranceDomesticSegment



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value175202225184226198229198171186199217215183205190191175166188228176202172152141144
Percentage of IncomeBeforeIncomeTaxes-2720.399.782.580.4108.486.4108.50.075.8115.6108.50.065.0115.8117.9121.883.798.798.9116.182.067.181.786.996.088.297.4

us-gaap:OperatingSegments, wrb:ReinsuranceandMonolineExcessSegment



Period End2020-03-312019-03-31
Value3644
Percentage of IncomeBeforeIncomeTaxes-564.519.5

wrb:InvestmentsAllowanceforCreditLossPeriodIncreaseDecrease



Period End2020-03-312019-03-31
Value-330
Percentage of InvestmentsAllowanceforCreditLossPeriodIncreaseDecrease100.00.0

wrb:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsUndiscountedBasisPriorYearsIncreaseDecrease



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value47312-3540-662-15-194104
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsUndiscountedBasisPriorYearsIncreaseDecrease100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredLossReserveDiscountAccretion



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-9-9-8-10-10-9-11-10-10-9-10-3612-12-13-12-11
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredLossReserveDiscountAccretion100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:LiabilityforUnpaidClaimsandClaimsAdjustmentExpenseForeignExchangeTranslation



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-7726-47-20-16-28-742-3201323-3913-4020
Percentage of LiabilityforUnpaidClaimsandClaimsAdjustmentExpenseForeignExchangeTranslation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:LiabilityforUnpaidClaimsandClaimsAdjustmentExpenseIncurredClaimsAdjustment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0-11-5-10-6-1-5-33-21-286895
Percentage of LiabilityforUnpaidClaimsandClaimsAdjustmentExpenseIncurredClaimsAdjustment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:MarketableSecuritiesRealizedGainLossExcludingOtherthanTemporaryImpairmentsNetofTax



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-13915854175538119263411444-53517121346703428211215
Percentage of MarketableSecuritiesRealizedGainLossExcludingOtherthanTemporaryImpairmentsNetofTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:OperatingLeaseRightOfUseAssetAccumulatedDepreciation



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value6053463
Percentage of OperatingLeaseRightOfUseAssetAccumulatedDepreciation100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

wrb:OtherComprehensiveIncomeLossSecuritiesAvailableforSaleWithAllowanceforCreditLossUnrealizedHoldingGainLossArisingDuringPeriodafterTax

us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges



Period End2020-03-312019-03-31
Value10
Percentage of OtherComprehensiveIncomeLossSecuritiesAvailableforSaleWithAllowanceforCreditLossUnrealizedHoldingGainLossArisingDuringPeriodafterTax100.0100.0

us-gaap:StatementEquityComponents

wrb:OtherComprehensiveIncomeUnrealizedGainsonOtherThanTemporarilyImpairedSecurities

us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value0000000000000010-12500000000
Percentage of OtherComprehensiveIncomeUnrealizedGainsonOtherThanTemporarilyImpairedSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:OtherRevenues



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value-551211271881851721481761491943071441511922881671491391961691481672002401741791441381171071211091041058985
Percentage of OtherRevenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value1131141001041068781
Percentage of OtherRevenues-203.689.753.655.971.849.854.8

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, wrb:InsuranceDomesticSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value8911131315191818860221820222726232324252426262826272627
Percentage of OtherRevenues-15.27.69.17.37.19.113.110.612.744.60.016.012.110.87.916.517.916.911.714.417.214.713.211.216.514.519.119.325.2

wrb:PaymentForStockOptionsExercisedNet



Period End2020-03-312019-03-31
Value30
Percentage of PaymentForStockOptionsExercisedNet100.00.0

wrb:PaymentstoAcquirePropertyPlantandEquipmentNet



Period End2020-03-312019-03-31
Value143
Percentage of PaymentstoAcquirePropertyPlantandEquipmentNet100.0100.0

wrb:ProceedsFromPaymentsToEquityMethodInvestments



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value9919010-131-383321560-11
Percentage of ProceedsFromPaymentsToEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:REalEstateRealizedGainLossonDisposal



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-30
Value0032407103005000085000
Percentage of REalEstateRealizedGainLossonDisposal100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0100.00.00.00.0

wrb:RealizedGainLossonInvestmentsIncludingEquityMethodInvestmentsExcludingOtherthanTemporaryImpairmentsandAllowances



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-143-221736819226948591834052771756251266271920721095243331924
Percentage of RealizedGainLossonInvestmentsIncludingEquityMethodInvestmentsExcludingOtherthanTemporaryImpairmentsandAllowances100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:RealizedGainLossonMarketableSecuritiesEquityMethodInvestmentsandOtherInvestmentsBeforeTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-177-2217368142269485918340527717567-853271920721095243331924
Percentage of RealizedGainLossonMarketableSecuritiesEquityMethodInvestmentsandOtherInvestmentsBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:RealizedGainLossonMarketableSecuritiesEquityMethodInvestmentsandOtherInvestmentsNetofTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-139-1815854111755383811926345011444-53517121346703428211215
Percentage of RealizedGainLossonMarketableSecuritiesEquityMethodInvestmentsandOtherInvestmentsNetofTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:RealizedGainLossonMarketableSecuritiesEquityMethodInvestmentsandOtherInvestmentsTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-06-30
Value-37-40151424141020641418276122-218967253818151168
Percentage of RealizedGainLossonMarketableSecuritiesEquityMethodInvestmentsandOtherInvestmentsTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:RevenuesFromWhollyOwnedInvestees



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value93123101899113095767010189696584801231011151071059211110110492109839168554965565347615251575149
Percentage of RevenuesFromWhollyOwnedInvestees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType

wrb:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue

us-gaap:RestrictedStockUnitsRSU



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-03-31
Value05900560058005600530049001
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementBusinessSegments

wrb:UnfavorableReserveDevelopmentNetOfPremiumOffsets

wrb:ReinsuranceandMonolineExcessSegment



Period End2020-03-312019-03-31
Value32
Percentage of UnfavorableReserveDevelopmentNetOfPremiumOffsets100.0100.0

us-gaap:AccruedInvestmentIncomeReceivable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value140138144140150144148141143136139136135127133127130123128129139120138123130118128126126127131135132133133139135138142134130
Percentage of AccruedInvestmentIncomeReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AdditionalPaidInCapitalCommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value1063105610451058105310631058106010571048104010571047103710271021101310059891003998991982974970967961956949945936944938941927923925935933926926
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value10561039
Percentage of AdditionalPaidInCapitalCommonStock100.097.8

us-gaap:AllowanceForLoanAndLeaseLossesRealEstate



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value222333333333332222222222211655131019182020
Percentage of AllowanceForLoanAndLeaseLossesRealEstate100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:AssetsFairValueDisclosure

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value618538614555494442633726745814685768660654347455274286259437321360306357384351490509514
Percentage of AssetsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value1397614429144631400913897137861385013587137351383114197139001402513404139301318212888125771252312826132891282913087125731246011919119271208311969
Percentage of AssetsFairValueDisclosure2260.52678.02353.62523.12808.33112.62186.21871.51841.71698.72069.71809.52123.12048.84005.02895.14691.24392.24820.12930.14128.43557.24274.83513.93242.03388.02433.62372.92327.6

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value1515153916291219232013121212111211111213873542444349515662
Percentage of AssetsFairValueDisclosure2.52.92.57.13.36.82.02.73.22.52.01.71.91.93.42.74.24.24.93.227.110.014.012.411.414.110.411.012.1

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-31
Value146101498315093146041440814259144971433314504146661489614681146981407114290136501317412875127961322512320
Percentage of AssetsFairValueDisclosure2363.02780.92456.22630.12911.63219.42288.31974.31944.91801.22171.71911.12225.02150.74108.42997.84795.44496.44925.03667.13502.1

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value13739138971376613400134551359613561131061319413242134791310713061128691301912311122181201211886119171202612122117801148211467111901112311100108511111511038110591085810639105781073310737
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value7181317
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis5.29.7

us-gaap:FinancialInstrument

srt:IndustrialProperty



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value217522602298217821122295
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis15.816.316.716.315.716.9

us-gaap:AssetBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value312328022758271926582462
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis22.720.220.020.319.818.1

us-gaap:CommercialMortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value284304356303351345
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis2.12.22.62.32.62.5

us-gaap:CorporateDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value400940384022394939474188
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis29.229.129.229.529.330.8

us-gaap:Corporation



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value254255243238252272
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis1.91.81.81.81.92.0

us-gaap:DebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value228323432371232223922396
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis16.616.917.217.317.817.6

us-gaap:DomesticCorporateDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value148214471397143114751502
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis10.810.410.210.711.011.1

us-gaap:ForeignGovernmentDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value809924841818820822
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis5.96.76.16.16.16.0

us-gaap:MortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value145316021680154615781609
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis10.611.512.211.511.711.8

us-gaap:OtherAggregatedInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value24519274260
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis0.20.00.10.20.30.4

us-gaap:PublicUtilityBonds



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value327325306312317330
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis2.42.32.22.32.42.4

us-gaap:ResidentialMortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value116912981323124212261264
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis8.59.39.69.39.19.3

us-gaap:RevenueSubjectToRefund



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value311364280298337408
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis2.32.62.02.22.53.0

us-gaap:SovereignDebtLocalGovernmentUnspecified



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value412432426427406403
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis3.03.13.13.23.03.0

us-gaap:SovereignDebtStateGovernmentUnspecified



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value365359340320334335
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis2.72.62.52.42.52.5

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value362737543662360737223815
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis26.427.026.626.927.728.1

us-gaap:USTreasuryAndGovernment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value715775800760728697
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis5.25.65.85.75.45.1

wrb:SpecialRevenue



Period End2019-12-312018-12-31
Value23432396
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis16.917.6

us-gaap:FairValueByMeasurementBasis

us-gaap:AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value5216520318811776101232285375
Percentage of AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value61614874
Percentage of AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax12.910.37.34.36.05.7

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:PreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value4514818818011072
Percentage of AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax87.189.792.795.794.094.3

us-gaap:FairValueByMeasurementBasis

us-gaap:AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value712937262526101094
Percentage of AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value602633211919
Percentage of AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax85.087.989.579.874.974.5

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:PreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1033566
Percentage of AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax15.012.110.520.225.125.5

us-gaap:FairValueByMeasurementBasis

us-gaap:AvailableForSaleEquitySecuritiesAmortizedCostBasis

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value375345277254249228234250219206
Percentage of AvailableForSaleEquitySecuritiesAmortizedCostBasis100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value200175166153148113
Percentage of AvailableForSaleEquitySecuritiesAmortizedCostBasis53.451.060.060.259.449.6

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:PreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value174169111101101115
Percentage of AvailableForSaleEquitySecuritiesAmortizedCostBasis46.649.040.039.840.650.4

us-gaap:FairValueByMeasurementBasis

us-gaap:AvailableForSaleSecurities

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value356480443416341279325472496576614612611669158286141150177153174170222257322283338434376
Percentage of AvailableForSaleSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value356480443416341279325472496576614612611669158286141150177153174170222257322283338434376
Percentage of AvailableForSaleSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue

us-gaap:AssetBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value262915291399158218482030
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue100.0100.0100.0100.0100.0100.0

us-gaap:CorporateDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value194142835646815162685
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue73.828.025.529.682.0132.2

us-gaap:DebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value614133412902305753387861
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue233.6218.4207.4193.1288.8387.2

us-gaap:ForeignGovernmentDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value139271237214263326
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue5.317.817.013.614.316.1

us-gaap:MortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value6964814203577701046
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue26.531.530.122.641.751.5

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value7154923653347281446
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue27.232.226.121.239.471.2

us-gaap:USTreasuryAndGovernment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value2013612198210326
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue0.89.08.76.211.416.1

us-gaap:FinancialInstrument, us-gaap:InvestmentSecondaryCategorization

us-gaap:AssetBackedSecurities, wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-31
Value011014
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue0.00.10.70.8

us-gaap:CorporateDebtSecurities, wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-31
Value55326583
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue2.12.44.24.5

us-gaap:ForeignGovernmentDebt, wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-31
Value4678114140
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue1.85.67.27.6

us-gaap:MortgageBackedSecurities, wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-31
Value14077
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue0.50.00.50.4

us-gaap:InvestmentSecondaryCategorization

wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-30
Value11711219824526715612565221068914017619611429698479136170
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue4.58.012.513.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue

us-gaap:AssetBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value2014755778101012501687
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue100.0100.0100.0100.0100.0100.0

us-gaap:CorporateDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value18863071991392231730
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue93.740.725.613.817.8102.5

us-gaap:DebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value527919771532138418694895
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue262.1261.8196.9137.0149.5290.1

us-gaap:ForeignGovernmentDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value114164133140192246
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue5.721.817.113.915.414.6

us-gaap:MortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value6093011592336334
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue30.339.920.52.32.919.8

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value6403652066470701
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue31.848.426.56.45.641.6

us-gaap:USTreasuryAndGovernment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value138355697195
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue0.711.17.20.67.811.6

us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue

us-gaap:AssetBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value614774621572598342
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue100.0100.0100.0100.0100.0100.0

us-gaap:CorporateDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value541211573281293954
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue8.815.725.357.4216.2278.5

us-gaap:DebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value86213631370167234682965
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue140.3176.1220.4292.3579.8865.1

us-gaap:ForeignGovernmentDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value24107103737080
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue4.013.816.712.911.823.3

us-gaap:MortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value86180261334734712
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue14.123.342.058.5122.7207.8

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value74127159270658744
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue12.216.425.747.3110.0217.3

us-gaap:USTreasuryAndGovernment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value7536592113130
Percentage of AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue1.26.910.616.219.038.2

us-gaap:AvailableForSaleSecuritiesEquitySecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value356480443416341279325472496576614612611669158286141150177153174170222257322283338434399376425561489443438511510561461357401
Percentage of AvailableForSaleSecuritiesEquitySecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:CommonStock, us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value137157139131127891572793113424104384034292713030293350526568102162159237329280
Percentage of AvailableForSaleSecuritiesEquitySecurities38.732.831.431.537.232.148.559.162.859.566.871.666.164.217.345.621.219.519.032.729.938.431.040.050.456.370.075.874.6

us-gaap:CommonStock, us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value00000000000087000000000000000
Percentage of AvailableForSaleSecuritiesEquitySecurities0.00.00.00.00.00.00.00.00.00.00.00.01.41.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock, us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value8988889899998888778981011011111
Percentage of AvailableForSaleSecuritiesEquitySecurities2.51.92.02.22.63.12.81.91.81.61.51.51.41.35.12.95.35.24.75.95.16.35.00.30.40.40.40.30.4

us-gaap:PreferredStock, us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value20230728927220117615417316421319016118621911914410010913290109901381491541189610093
Percentage of AvailableForSaleSecuritiesEquitySecurities57.063.965.265.459.063.447.536.733.237.031.026.430.532.875.350.370.972.974.359.062.953.262.358.348.041.928.523.124.8

us-gaap:PreferredStock, us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value66633331010103333333333333333330
Percentage of AvailableForSaleSecuritiesEquitySecurities1.81.41.50.91.21.41.22.32.21.90.60.60.60.52.31.32.62.42.02.42.12.21.71.51.21.31.10.90.2

us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementFrequency

us-gaap:CommonStock, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-31
Value146166148140136981662883203524194474214453513837374276160
Percentage of AvailableForSaleSecuritiesEquitySecurities41.234.733.433.739.835.251.361.064.661.168.373.068.966.622.448.526.524.723.744.656.7

us-gaap:PreferredStock, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-31
Value20931329527620518015818417522419416519022312314710411313594122
Percentage of AvailableForSaleSecuritiesEquitySecurities58.865.366.666.360.264.848.739.035.438.931.727.031.133.477.651.573.575.376.355.443.3

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value137157139131127891572793113424104384034292713030293350526568102162159237329280
Percentage of AvailableForSaleSecuritiesEquitySecurities38.732.831.431.537.232.148.559.162.859.566.871.666.164.217.345.621.219.519.032.729.938.431.040.050.456.370.075.874.6

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value20230728927220117615417316421319016119522711914410010913290109901381491541189610093
Percentage of AvailableForSaleSecuritiesEquitySecurities57.063.965.265.459.063.447.536.733.237.031.026.431.933.975.350.370.972.974.359.062.953.262.358.348.041.928.523.124.8

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value1515151212121219192013121212111111111212121414444552
Percentage of AvailableForSaleSecuritiesEquitySecurities4.33.23.53.13.74.54.04.24.03.52.22.12.01.97.44.17.87.66.88.37.28.56.71.81.51.81.51.20.5

us-gaap:FairValueByMeasurementBasis

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value356480443416341279325472496576
Percentage of AvailableForSaleSecuritiesEquitySecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value356480443416341279325472496576
Percentage of AvailableForSaleSecuritiesEquitySecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument

us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value14616614814013698
Percentage of AvailableForSaleSecuritiesEquitySecurities41.234.733.433.739.835.2

us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:PreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value209313295276205180
Percentage of AvailableForSaleSecuritiesEquitySecurities58.865.366.666.360.264.8

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value14616614814013698
Percentage of AvailableForSaleSecuritiesEquitySecurities41.234.733.433.739.835.2

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:PreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value209313295276205180
Percentage of AvailableForSaleSecuritiesEquitySecurities58.865.366.666.360.264.8

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-31
Value356480443416341279325472496576614612611669158286141150177170283
Percentage of AvailableForSaleSecuritiesEquitySecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument, us-gaap:InvestmentSecondaryCategorization

us-gaap:AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1

us-gaap:AssetBackedSecurities, wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-31
Value4.06.07.08.0
Percentage of AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1100.0100.0100.0100.0

us-gaap:CorporateDebtSecurities, wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-31
Value15.012.011.015.0
Percentage of AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1375.0200.0157.1187.5

us-gaap:ForeignGovernmentDebt, wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-31
Value17.021.012.016.0
Percentage of AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1425.0350.0171.4200.0

us-gaap:MortgageBackedSecurities, wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-31
Value13.04.04.04.0
Percentage of AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1325.066.757.150.0

us-gaap:InvestmentSecondaryCategorization

wrb:NoninvestmentGradeInvestmentsatLossLessthan5Million



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-30
Value49.043.034.043.045.033.027.021.015.031.031.033.039.028.020.014.018.022.020.026.031.0
Percentage of AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions11225.0716.7485.7537.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByMeasurementBasis

us-gaap:CashAndCashEquivalentsFairValueDisclosure

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value965102381212589378178199119569507737886087958739488377638797566146741342842643839966658905
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value965102381212589378178199119569507737886087958739488377638797566146741342842643839966658905
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument

us-gaap:DebtInstrumentFaceAmount

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Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value10812312581153775734
Percentage of DebtInstrumentFaceAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0

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Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value0140140140150150150
Percentage of DebtInstrumentFaceAmount0.0113.41123.72532.4183.597.7194.4

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Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value0300300300300300300
Percentage of DebtInstrumentFaceAmount0.0242.02396.75401.5367.0195.4388.7

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Period End2019-12-31
Value300
Percentage of DebtInstrumentFaceAmount275.7

us-gaap:LongtermDebtType

us-gaap:SubordinatedDebt



Period End2019-12-312018-12-312017-12-312016-12-31
Value1235935350350
Percentage of DebtInstrumentFaceAmount1135.1754.12796.26301.8

wrb:SeniorNotesandOtherDebt



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value1435189117791772185821301703
Percentage of DebtInstrumentFaceAmount1319.21525.214218.031917.72273.01387.22207.6

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLoss



Period End2020-03-312019-12-31
Value670
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss100.00.0

us-gaap:FinancialInstrument

srt:IndustrialProperty



Period End2020-03-31
Value3
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss5.2

us-gaap:AssetBackedSecurities



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:CommercialMortgageBackedSecurities



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:CorporateDebtSecurities



Period End2020-03-312019-12-31
Value60
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss9.60.0

us-gaap:Corporation



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:DebtSecurities



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:DomesticCorporateDebtSecurities



Period End2020-03-31
Value2
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss4.3

us-gaap:ForeignGovernmentDebtSecurities



Period End2020-03-312019-12-31
Value600
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss90.40.0

us-gaap:MortgageBackedSecurities



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:OtherAggregatedInvestments



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:PublicUtilityBonds



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:ResidentialMortgageBackedSecurities



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:RevenueSubjectToRefund



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:SovereignDebtLocalGovernmentUnspecified



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:SovereignDebtStateGovernmentUnspecified



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:USTreasuryAndGovernment



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:FinancialInstrument, wrb:CumulativeEffectPeriodOfAdoption

us-gaap:CorporateDebtSecurities, wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-31
Value0.0
Percentage of DebtSecuritiesAvailableForSaleAllowanceForCreditLoss0.0

us-gaap:ForeignGovernmentDebtSecurities, wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-31
Value35
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wrb:CumulativeEffectPeriodOfAdoption

wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-31
Value35
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us-gaap:DebtSecuritiesAvailableForSaleAndHeldToMaturity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value136661418014086137321364013606
Percentage of DebtSecuritiesAvailableForSaleAndHeldToMaturity100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value7231307
Percentage of DebtSecuritiesAvailableForSaleAndHeldToMaturity5.19.6

us-gaap:DebtSecuritiesHeldToMaturityAllowanceForCreditLoss



Period End2020-03-312019-12-31
Value107000.00.0
Percentage of DebtSecuritiesHeldToMaturityAllowanceForCreditLoss100.00.0

us-gaap:FinancialInstrument

us-gaap:ResidentialMortgageBackedSecurities



Period End2020-03-31
Value0.0
Percentage of DebtSecuritiesHeldToMaturityAllowanceForCreditLoss0.0

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-31
Value107000.0
Percentage of DebtSecuritiesHeldToMaturityAllowanceForCreditLoss100.0

wrb:CumulativeEffectPeriodOfAdoption

wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-31
Value69000.0
Percentage of DebtSecuritiesHeldToMaturityAllowanceForCreditLoss0.0

us-gaap:DeferredIncomeTaxAssetsNet



Period End2020-03-312019-12-312018-12-312017-12-31
Value830350
Percentage of DeferredIncomeTaxAssetsNet100.00.0100.00.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value066
Percentage of DeferredIncomeTaxAssetsNet0.0188.8

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Period End2019-12-312018-12-312017-12-312016-12-312015-12-312015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value410334400606458204841724594110082
Percentage of DeferredIncomeTaxLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0

us-gaap:DeferredIncomeTaxLiabilitiesNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value01715384300098
Percentage of DeferredIncomeTaxLiabilitiesNet0.0100.0100.0100.0100.00.00.00.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value220
Percentage of DeferredIncomeTaxLiabilitiesNet129.00.0

us-gaap:DeferredPolicyAcquisitionCosts



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value542517527520515497513514513507534539544537564563547513524521507488492483475452452433425404400386377448450440429405412409391
Percentage of DeferredPolicyAcquisitionCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsGross



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value425404330477455448431447433393
Percentage of DeferredTaxAssetsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards



Period End2019-12-312018-12-312017-12-31
Value373733
Percentage of DeferredTaxAssetsOperatingLossCarryforwards100.0100.0100.0

us-gaap:DeferredTaxAssetsOther



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value6358491048910192838226
Percentage of DeferredTaxAssetsOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value60565972626052494339
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value89826264549626869
Percentage of DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves



Period End2019-12-312018-12-312018-01-012017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value1361304770861007787119119152
Percentage of DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value120112110187176165149132118106
Percentage of DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value10399100173162152136120
Percentage of DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value1213122120221112
Percentage of DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesInvestments



Period End2019-12-312018-12-312017-12-312016-12-312015-12-31
Value7351418579
Percentage of DeferredTaxLiabilitiesInvestments100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesOther



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value50536353160135114999320
Percentage of DeferredTaxLiabilitiesOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment



Period End2019-12-312018-12-312017-12-312016-12-312015-12-31
Value4739313433
Percentage of DeferredTaxLiabilitiesPropertyPlantAndEquipment100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value9335151238115175148274
Percentage of DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DepositContractsLiabilities



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value41454751546872758095
Percentage of DepositContractsLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentRisk, us-gaap:Position

us-gaap:DerivativeFairValueOfDerivativeNet

us-gaap:Option, us-gaap:Long



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value917000.09000.0380000.0313000.01000.037000.089000.0200000.01000000.01000000.01000000.01000000.0600000.01000000.0
Percentage of DerivativeFairValueOfDerivativeNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Option, us-gaap:Short



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value00000000081102
Percentage of DerivativeFairValueOfDerivativeNet59.4622.294.593.047100.0156.8312.4150.020.0800.0100.0100.066.7200.0

us-gaap:DerivativeInstrumentRisk, us-gaap:Position

us-gaap:DerivativeNotionalAmount

us-gaap:Option, us-gaap:Long



Period End2020-03-312019-12-312019-09-30
Value231512
Percentage of DerivativeNotionalAmount100.0100.0100.0

us-gaap:Option, us-gaap:Short



Period End2020-03-312019-12-312019-09-30
Value291712
Percentage of DerivativeNotionalAmount126.8110.3101.6

us-gaap:DevelopmentInProcess



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value4477547927577066771159111510931017939869789727666779747710646611561534507482456431368324323
Percentage of DevelopmentInProcess100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:DueToAffiliateCurrentAndNoncurrent

srt:ParentCompany



Period End2019-12-312018-12-31
Value107116
Percentage of DueToAffiliateCurrentAndNoncurrent100.0100.0

us-gaap:EquityMethodInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value117812131227140113591332125112081161115511191190123811981231120511791170114011231214121110209849561067873858793809747728679680610606548451409421418
Percentage of EquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentType

us-gaap:RealEstateFunds



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value328412437654651642632622624606614611654641
Percentage of EquityMethodInvestments27.834.035.646.747.948.250.551.553.852.554.951.452.853.6

wrb:EnergyFunds



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value1521561737573757976808291
Percentage of EquityMethodInvestments12.912.914.15.45.45.66.46.37.07.27.6

wrb:FinancialServicesFunds



Period End2020-03-312019-12-312019-09-302018-12-31
Value318280282195
Percentage of EquityMethodInvestments27.023.123.014.7

wrb:OtherFunds



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value229216187671634615539509455465419419413391
Percentage of EquityMethodInvestments19.517.915.347.946.746.243.142.139.240.337.535.333.432.6

wrb:TransportationFunds



Period End2020-03-312019-12-312019-09-302018-12-31
Value150147146136
Percentage of EquityMethodInvestments12.812.111.910.3

us-gaap:EquitySecuritiesFvNi



Period End2019-12-312018-12-31
Value480279
Percentage of EquitySecuritiesFvNi100.0100.0

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:CommonStock, us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value15789
Percentage of EquitySecuritiesFvNi32.832.1

us-gaap:CommonStock, us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value98
Percentage of EquitySecuritiesFvNi1.93.1

us-gaap:PreferredStock, us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value307176
Percentage of EquitySecuritiesFvNi63.963.4

us-gaap:PreferredStock, us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value63
Percentage of EquitySecuritiesFvNi1.41.4

us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementFrequency

us-gaap:CommonStock, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value16698
Percentage of EquitySecuritiesFvNi34.735.2

us-gaap:PreferredStock, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value313180
Percentage of EquitySecuritiesFvNi65.364.8

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value15789
Percentage of EquitySecuritiesFvNi32.832.1

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value307176
Percentage of EquitySecuritiesFvNi63.963.4

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value1512
Percentage of EquitySecuritiesFvNi3.24.5

us-gaap:FairValueByMeasurementBasis

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2019-12-312018-12-31
Value480279
Percentage of EquitySecuritiesFvNi100.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2019-12-312018-12-31
Value480279
Percentage of EquitySecuritiesFvNi100.0100.0

us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument

us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:CommonStock



Period End2019-12-312018-12-31
Value16698
Percentage of EquitySecuritiesFvNi34.735.2

us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:PreferredStock



Period End2019-12-312018-12-31
Value313180
Percentage of EquitySecuritiesFvNi65.364.8

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:CommonStock



Period End2019-12-312018-12-31
Value16698
Percentage of EquitySecuritiesFvNi34.735.2

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:PreferredStock



Period End2019-12-312018-12-31
Value313180
Percentage of EquitySecuritiesFvNi65.364.8

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-31
Value480279
Percentage of EquitySecuritiesFvNi100.0100.0

us-gaap:FairValueByMeasurementBasis

us-gaap:EquitySecuritiesFvNiCost

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2019-12-312018-12-31
Value345228
Percentage of EquitySecuritiesFvNiCost100.0100.0

us-gaap:FairValueByMeasurementBasis, us-gaap:FinancialInstrument

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:CommonStock



Period End2019-12-312018-12-31
Value175113
Percentage of EquitySecuritiesFvNiCost51.049.6

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:PreferredStock



Period End2019-12-312018-12-31
Value169115
Percentage of EquitySecuritiesFvNiCost49.050.4

us-gaap:FairValueByMeasurementBasis

us-gaap:FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value11981198908907907907907907897728728727727727727727446340340340340340339339339339339339243
Percentage of FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value10921274955969945840913929929769728786750687779764462355343338354332326325301288302327252
Percentage of FairValueLiabilitiesMeasuredOnRecurringBasisSubordinatedDebtObligations91.1106.3105.2106.8104.292.6100.7102.4103.6105.6100.0108.1103.194.5107.1105.1103.5104.6100.899.6104.297.896.095.888.784.989.096.3103.6

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue

us-gaap:AssetBackedSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312013-12-31
Value000000000000000002042
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue0.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-312011-12-31
Value89888898999988887789810110111111
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue0.00.00.035936.035152.08682.88993.18836.65586.55447.75394.85225.44917.94783.64387.04368.63793.93934.20.00.00.052.10.00.00.02.90.00.00.00.0

us-gaap:DebtSecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-312011-12-31
Value00000000000000000001202437384246505967
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue0.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0177.40.00.00.0100.70.00.00.0100.40.00.00.00.0

us-gaap:EquitySecurities, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-312011-12-31
Value151515121212121919201312121211111111121212141444455213
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue0.00.00.051680.050932.012667.712750.519573.312238.711751.77610.97342.26963.76784.76373.06313.85641.65755.30.00.00.070.10.00.00.011.70.00.00.00.0

us-gaap:PreferredStock, us-gaap:FairValueInputsLevel3



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-312011-12-31
Value6663333101010333333333333333333012
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue0.00.00.015744.015780.03984.83757.410736.66652.16304.12216.12116.82045.82001.11985.91945.21847.71821.10.00.00.018.00.00.00.08.80.00.00.00.0

us-gaap:TradingAssetsExcludingDebtAndEquitySecurities, us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-312011-12-31
Value00263170030000000000172042010000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue0.00.0104824.014352.017482.80.00.02357.10.00.00.034.10.00.08.066.088.40.00.00.03.50.00.00.04.20.00.00.00.0

us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-312011-12-31
Value1515391629121923201312121211121111121387354244434951566282
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue0.00.0156604.065384.030250.512850.519673.314695.711851.77710.97442.27097.86884.76473.06421.85807.66021.10.00.00.0174.40.00.00.0116.20.00.00.00.0

us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue

us-gaap:FairValueInputsLevel3



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-312013-09-302013-06-302012-12-312011-12-31
Value001400000000000000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue0.00.0100.00.0100.00.00.00.00.00.00.0100.00.00.00.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FinancialInstrumentsSoldNotYetPurchasedAtFairValue

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value3637645135106162114
Percentage of FinancialInstrumentsSoldNotYetPurchasedAtFairValue100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value00001006
Percentage of FinancialInstrumentsSoldNotYetPurchasedAtFairValue0.00.00.00.24.20.00.15.7

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value0.0793000.00.00.00.00.00.020000.0
Percentage of FinancialInstrumentsSoldNotYetPurchasedAtFairValue0.02.10.00.00.00.00.00.0

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value3638645137106162
Percentage of FinancialInstrumentsSoldNotYetPurchasedAtFairValue100.0102.1100.0100.2104.2100.0100.1

us-gaap:FinancingReceivableAllowanceForCreditLosses



Period End2020-03-312019-12-31
Value32
Percentage of FinancingReceivableAllowanceForCreditLosses100.0100.0

us-gaap:FinancingReceivablePortfolioSegment

us-gaap:CommercialPortfolioSegment



Period End2020-03-312019-12-31
Value20
Percentage of FinancingReceivableAllowanceForCreditLosses63.530.0

us-gaap:CommercialRealEstatePortfolioSegment



Period End2020-03-312019-12-31
Value11
Percentage of FinancingReceivableAllowanceForCreditLosses36.570.0

us-gaap:FinancingReceivablePortfolioSegment, wrb:CumulativeEffectPeriodOfAdoption

us-gaap:CommercialPortfolioSegment, wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-31
Value548000.0
Percentage of FinancingReceivableAllowanceForCreditLosses25.5

us-gaap:CommercialRealEstatePortfolioSegment, wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-31
Value-905000.0
Percentage of FinancingReceivableAllowanceForCreditLosses-42.2

wrb:CumulativeEffectPeriodOfAdoption

wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-31
Value-357000.0
Percentage of FinancingReceivableAllowanceForCreditLosses-16.6

us-gaap:FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value11122222222222222222222222
Percentage of FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value00011111111111000000000003
Percentage of FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.00.00.00.0100.0

us-gaap:FinancingReceivableRecordedInvestmentNonaccrualStatus



Period End2020-03-312019-12-312019-09-302019-06-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312011-09-302010-12-31
Value00001111444559116359121444
Percentage of FinancingReceivableRecordedInvestmentNonaccrualStatus100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:HeldToMaturitySecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value787878787878787979797979888888889696101101101101101101101101101101102102103116115115114116115
Percentage of HeldToMaturitySecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:ResidentialMortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value78891010
Percentage of HeldToMaturitySecurities10.010.611.311.912.813.7

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value707069696867
Percentage of HeldToMaturitySecurities90.089.488.788.187.286.3

us-gaap:HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-31
Value1213141413121212131516161514-19-21-19-18-18-17-20
Percentage of HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:ResidentialMortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value001111
Percentage of HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain6.67.16.97.68.49.8

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value111313131211
Percentage of HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain93.492.993.192.491.690.2

us-gaap:HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value787878787878787979797979888888889696101101101101101101101101101101102102103116115115114116115
Percentage of HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:ResidentialMortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value78891010
Percentage of HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment10.010.611.311.912.813.7

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value707069696867
Percentage of HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment90.089.488.788.187.286.3

us-gaap:HeldToMaturitySecuritiesFairValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value919293929291919192959696103102107109116114119119122121121120119116118118125127127138134133132128122
Percentage of HeldToMaturitySecuritiesFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:ResidentialMortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value899101112
Percentage of HeldToMaturitySecuritiesFairValue9.510.110.611.312.213.1

us-gaap:USStatesAndPoliticalSubdivisions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value828383828179
Percentage of HeldToMaturitySecuritiesFairValue90.589.989.488.787.886.9

us-gaap:HeldToMaturitySecuritiesRestricted



Period End2019-12-312018-12-312017-12-312016-12-312015-12-31
Value121913329951022963
Percentage of HeldToMaturitySecuritiesRestricted100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

naics:ZZ523991



Period End2019-12-31
Value1639
Percentage of HeldToMaturitySecuritiesRestricted134.5

us-gaap:StatementBusinessSegments

us-gaap:InsuranceRelatedAssessments



Period End2019-12-312018-12-312017-12-312016-12-312015-12-31
Value380328308178182
Percentage of HeldToMaturitySecuritiesRestricted31.224.631.017.418.9

wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value36
Percentage of HeldToMaturitySecuritiesRestricted3.0

us-gaap:IncomeTaxesReceivable



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-06-302009-12-31
Value1300145567240500921502360
Percentage of IncomeTaxesReceivable100.0100.00.0100.0100.0100.0100.00.0100.00.00.0100.0100.0100.00.0100.0100.00.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value189
Percentage of IncomeTaxesReceivable140.71289.9

us-gaap:Investments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value1803918473185931824617961177231784117602176541745017561173651736716649168321611015587153511519715583160561559115605152481507214548145041455814604144671428714222137801343913293133601324212995131471285613050
Percentage of Investments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:JuniorSubordinatedNotes



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value11981198908907907907907907897728728727727727727727446340340340340340339339339339339339243
Percentage of JuniorSubordinatedNotes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value1198907
Percentage of JuniorSubordinatedNotes100.0100.0

us-gaap:LiabilityForAsbestosAndEnvironmentalClaimsNet



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value24283031333636343436
Percentage of LiabilityForAsbestosAndEnvironmentalClaimsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value12732125831239612320120931196611872117361178411670116541132411224111971109710897107881066910661106221047410369103141025610214100801006199219809975195629488939493379261919591729016913591099071
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value107851069710582105141037310248102061007710100100561004898239722959095469442937292448970868384118172799981478122
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:CumulativeEffectPeriodOfAdoption

wrb:CumulativeEffectPeriodOfAdoptionAdjustedBalance



Period End2019-12-312018-12-31
Value1070310248
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet100.1100.0

wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-312018-12-31
Value50
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet0.10.0

us-gaap:LoansAndLeasesReceivableGrossCarryingAmount



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value87919294959496987579749610323113142149273286259280322343655373343401
Percentage of LoansAndLeasesReceivableGrossCarryingAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value5551
Percentage of LoansAndLeasesReceivableGrossCarryingAmount60.854.4

us-gaap:FinancingReceivablePortfolioSegment

us-gaap:CommercialPortfolioSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-31
Value34333332333233351213141314
Percentage of LoansAndLeasesReceivableGrossCarryingAmount39.236.236.334.735.134.335.035.816.717.119.913.761.4

us-gaap:CommercialRealEstatePortfolioSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-31
Value52585861626262626366598292
Percentage of LoansAndLeasesReceivableGrossCarryingAmount60.863.863.765.364.965.765.064.283.382.980.186.3394.6

us-gaap:FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable

us-gaap:CommercialPortfolioSegment



Period End2019-12-312018-12-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value333213141417202772838477788386766165
Percentage of LoansAndLeasesReceivableGrossCarryingAmount36.234.317.113.961.415.514.418.426.629.132.627.524.424.413.120.417.816.3

us-gaap:CommercialRealEstatePortfolioSegment



Period End2019-12-312018-12-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value586266899296122121200203174203243259569297282336
Percentage of LoansAndLeasesReceivableGrossCarryingAmount63.865.782.986.1394.684.585.681.673.470.967.472.575.675.686.979.682.283.7

us-gaap:LoansReceivable



Period End2019-12-312018-12-312017-12-312016-12-312015-12-31
Value919479106273
Percentage of LoansAndLeasesReceivableGrossCarryingAmount100.0100.0100.0456.0100.0

us-gaap:LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value014531433113133021
Percentage of LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LoansReceivableFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value9194959697979810078827697105108116145151275289262283325346659376346406
Percentage of LoansReceivableFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value879192949594969875797496103106113142149273286259280322343655373343411359401
Percentage of LoansReceivableFairValueDisclosure95.697.097.097.797.797.797.797.797.097.196.998.598.698.697.998.398.399.099.098.998.999.099.099.599.299.10.00.098.9

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value9194959697979810078827697105108116145151275289262283325346659376346417363406
Percentage of LoansReceivableFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0

us-gaap:FinancingReceivablePortfolioSegment

us-gaap:CommercialPortfolioSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-31
Value34343534353435361415161415
Percentage of LoansReceivableFairValueDisclosure37.536.736.835.535.835.135.736.518.218.421.215.014.7

us-gaap:CommercialRealEstatePortfolioSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-31
Value56596062626363636466608292
Percentage of LoansReceivableFairValueDisclosure62.563.363.264.564.264.964.363.581.881.678.885.085.3

us-gaap:FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable

us-gaap:CommercialPortfolioSegment



Period End2019-12-312018-12-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value343415151519222774848477808587776267
Percentage of LoansReceivableFairValueDisclosure36.735.118.415.214.716.515.218.126.929.332.327.224.624.613.320.618.116.6

us-gaap:CommercialRealEstatePortfolioSegment



Period End2019-12-312018-12-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value596366899297123124201204177206245261571298284339
Percentage of LoansReceivableFairValueDisclosure63.364.981.684.885.383.584.881.973.170.767.772.875.475.486.779.481.983.4

us-gaap:FairValueByMeasurementBasis

us-gaap:LongTermDebtFairValue

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value14321427143418731875188217901792178217691759175917591760176218081814184418381843211221152122169716921692169616951871
Percentage of LongTermDebtFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value14541582159720191985196818761918192119451946195219271914199720112018202920472025238823442341193918971861188718892190
Percentage of LongTermDebtFairValue101.5110.8111.4107.8105.9104.6104.8107.0107.8110.0110.6111.0109.5108.8113.3111.2111.2110.0111.3109.8113.1110.8110.4114.3112.1110.0111.3111.4117.0

us-gaap:DebtInstrument

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo

wrb:SubsidiaryDebt



Period End2019-12-312017-12-31
Value24
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo100.0100.0

us-gaap:MortgageLoansOnRealEstateCommercialAndConsumerNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value879192949594969875797496103106113142149273286259280322343655373343411359456401371325357263283311348353357373381
Percentage of MortgageLoansOnRealEstateCommercialAndConsumerNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingLeaseLiability



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value224230226209215
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0

us-gaap:OtherAssets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value764762708734695501478477483434423433501402408530517442434430414369529327295335343376320242154153195192190192216198171164154
Percentage of OtherAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value1312
Percentage of OtherAssets1.72.5

us-gaap:OtherLiabilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value10051244126712581046100510089358529819231051775916968828754837820776673859938728679848832758844981912881801866924835808836795754779
Percentage of OtherLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:ParentCompany



Period End2019-12-312018-12-31
Value118115
Percentage of OtherLiabilities9.511.5

us-gaap:PreferredStockParOrStatedValuePerShare



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1100.00.1100.0100.0100.00.10.10.10.10.10.10.10.1
Percentage of PreferredStockParOrStatedValuePerShare100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PreferredStockSharesAuthorized



Period End2019-12-312018-12-312018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value5555555555555555555555000550005000500055555555
Percentage of PreferredStockSharesAuthorized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PreferredStockSharesIssued



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312010-09-302010-06-302009-12-31
Value505550000000000000000000000000000000
Percentage of PreferredStockSharesIssued100.00.0100.0100.0100.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PremiumsAndOtherReceivablesNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value20751997200920341964180718721902184517731818186717661701174218431749166917201766170616511681174816511557158515821504144014091347130712061195124111791087106911121047
Percentage of PremiumsAndOtherReceivablesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PremiumsReceivableAllowanceForDoubtfulAccounts



Period End2020-03-312019-12-31
Value2119
Percentage of PremiumsReceivableAllowanceForDoubtfulAccounts100.0100.0

wrb:CumulativeEffectPeriodOfAdoption

wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-31
Value1
Percentage of PremiumsReceivableAllowanceForDoubtfulAccounts6.4

us-gaap:PrepaidReinsurancePremiums



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value576567547538516498497503490472473482451413429450429394400415410395418431404367381382345316311305274258275275265215226235211
Percentage of PrepaidReinsurancePremiums100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RealEstateInvestmentPropertyAccumulatedDepreciation



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-31
Value665953554544403629252018161413121097541001917151311102
Percentage of RealEstateInvestmentPropertyAccumulatedDepreciation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RealEstateInvestmentPropertyNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-31
Value2084210521022067201919571917188318331469139113171237118411081024986936873820761731703530752715647589264282279
Percentage of RealEstateInvestmentPropertyNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RealEstateInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-31
Value2084210521022067201919571917188318331469139113171237118411081024986936873820761731703530752715647589588606433360355342346320
Percentage of RealEstateInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:ReceivablesFromBrokersDealersAndClearingOrganizations



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value132423209402322347191119261892971642948418534937338340141037105774304123144446
Percentage of ReceivablesFromBrokersDealersAndClearingOrganizations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:ReinsurancePayable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value368360336294262256231252248246228221218213261246256224230225218237255272236276285337298316303299268241254264227215211220208
Percentage of ReinsurancePayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value194618141805171916651659168416051500150215501455
Percentage of ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReinsuranceRecoverables



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value213320792040194119321859184118681783173916461640174316921602155815321559153315191503145214641508153315251477144114501309127012421215118711301173107010761062972
Percentage of ReinsuranceRecoverables100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CededCreditRisk

wrb:AlleghanyGroup



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value1691501521501389796
Percentage of ReinsuranceRecoverables7.97.88.68.69.06.56.3

wrb:ArchCapitalGroup



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value27212121232325
Percentage of ReinsuranceRecoverables1.31.11.21.21.51.61.7

wrb:AxisCapital



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value93858272696365
Percentage of ReinsuranceRecoverables4.44.44.64.24.64.24.3

wrb:BerkshireHathaway



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value82875649474853
Percentage of ReinsuranceRecoverables3.94.53.22.83.13.23.5

wrb:ChubbLtd.



Period End2019-12-312018-12-312017-12-312016-12-312015-12-31
Value1524303545
Percentage of ReinsuranceRecoverables0.71.31.72.03.0

wrb:CreditRiskReinsurersSubtotalExcludingResidualMarketPools



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value181415831371117710299971064
Percentage of ReinsuranceRecoverables85.082.076.967.567.266.469.4

wrb:EverestReMember



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value55625053474129
Percentage of ReinsuranceRecoverables2.63.22.83.13.12.81.9

wrb:HannoverReGroup



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value95776452484335
Percentage of ReinsuranceRecoverables4.54.03.63.03.22.92.3

wrb:KoreanRe



Period End2019-12-312018-12-31
Value6452
Percentage of ReinsuranceRecoverables3.02.7

wrb:LibertyMutual



Period End2019-12-312018-12-312017-12-31
Value493222
Percentage of ReinsuranceRecoverables2.31.71.3

wrb:LloydsOfLondon



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value20121515211892109117
Percentage of ReinsuranceRecoverables9.411.18.66.86.07.37.6

wrb:MunichRe



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value243164156130121141193
Percentage of ReinsuranceRecoverables11.48.58.87.57.99.412.6

wrb:OtherReinsurers



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value308289293246213212230
Percentage of ReinsuranceRecoverables14.515.016.414.113.914.115.1

wrb:PartnerRe



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value1271038774657067
Percentage of ReinsuranceRecoverables6.05.44.94.34.34.74.4

wrb:QatarReGRP



Period End2019-12-312018-12-31
Value2227
Percentage of ReinsuranceRecoverables1.11.4

wrb:RenaissanceRe



Period End2019-12-312018-12-312017-12-31
Value793927
Percentage of ReinsuranceRecoverables3.72.11.5

wrb:ResidualMarketPools



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value319348411566503505468
Percentage of ReinsuranceRecoverables15.018.023.132.532.833.630.6

wrb:SwissRe



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value179150129120115101104
Percentage of ReinsuranceRecoverables8.47.87.36.97.56.76.8

us-gaap:ReinsuranceRecoverablesAllowance



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-312011-12-31
Value601110111111111111111122111223
Percentage of ReinsuranceRecoverablesAllowance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wrb:CumulativeEffectPeriodOfAdoption

wrb:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2019-12-31
Value5
Percentage of ReinsuranceRecoverablesAllowance858.8

us-gaap:ReinsuranceRecoverablesGross



Period End2019-12-312018-12-312017-12-312017-03-312016-12-312016-03-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value18851717161315021606141514241399139713391165
Percentage of ReinsuranceRecoverablesGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReinsuranceRecoverablesOnPaidAndUnpaidLosses



Period End2020-03-312019-12-312018-12-312017-12-312016-12-31
Value21781885171716131606
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses100.0100.0100.0100.0100.0

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:OtherInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value46342732
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses2.52.01.72.0

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value89
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses4.8

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value113
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses6.0

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value241567
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses1.30.90.40.5

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value38
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses2.0

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value518451392362
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses27.526.324.322.5

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value509344305278
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses27.020.118.917.3

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value243293275210
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses12.917.117.113.1

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value300
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses16.0

us-gaap:StatementBusinessSegments

wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value1643155114781532
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses87.290.391.695.3

wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value241
Percentage of ReinsuranceRecoverablesOnPaidAndUnpaidLosses12.8

us-gaap:ConsolidatedEntities

us-gaap:SeniorNotes

srt:ParentCompany



Period End2019-12-312018-12-31
Value13181758
Percentage of SeniorNotes100.0100.0

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber

us-gaap:RestrictedStockUnitsRSU



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value43347748624158533044443
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount



Period End2019-12-312018-12-31
Value529563
Percentage of ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount100.0100.0

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.0
Percentage of ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount0.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value107
Percentage of ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount20.4

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value-410
Percentage of ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount-77.5

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value10
Percentage of ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount2.1

us-gaap:StatementBusinessSegments

wrb:InsuranceSegment



Period End2019-12-312018-12-31
Value10434
Percentage of ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount2.177.1

wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value518
Percentage of ShortdurationInsuranceContractsDiscountedLiabilitiesAggregateDiscount97.9

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.009
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight100.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.05
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight555.6

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0030.0040.0040.005
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight33.30.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.031
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight344.4

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0340.030.0350.042
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight377.80.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0260.0160.0290.017
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight288.90.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0040.0030.0010.005
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight44.40.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.017
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight188.9

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.036
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive100.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.114
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive316.7

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0680.0680.0630.065
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive188.90.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.023
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive63.9

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.140.1380.1390.134
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive388.90.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0990.0940.0960.092
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive275.00.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0010.0010.00.006
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive2.80.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.06
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive166.7

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.059
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour100.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.131
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour222.0

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.1080.1070.1040.106
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour183.10.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.031
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour52.5

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.1660.1680.1680.164
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour281.40.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.1520.1660.1690.178
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour257.60.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0180.0160.0170.022
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour30.50.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.093
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour157.6

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.008
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine100.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.039
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine487.5

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0020.0020.0010.002
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine25.00.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.033
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine412.5

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0290.0280.0290.034
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine362.50.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0380.0430.0270.01
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine475.00.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.00.00.0010.004
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine0.00.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.015
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine187.5

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.349
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne100.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.068
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne19.5

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.3930.3970.4030.401
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne112.60.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.045
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne12.9

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0780.080.0790.079
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne22.30.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0870.0870.090.085
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne24.90.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.5880.5960.6020.585
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne168.50.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.231
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne66.2

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.026
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven100.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.062
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven238.5

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0140.010.0090.009
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven53.80.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.027
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven103.8

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0540.0590.0570.063
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven207.70.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0350.0350.0320.018
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven134.60.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0040.0040.0030.009
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven15.40.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.027
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven103.8

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.024
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix100.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.089
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix370.8

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.030.0350.0350.033
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix125.00.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.031
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix129.2

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0860.0820.0860.084
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix358.30.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0890.0910.0640.052
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix370.80.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0050.0030.0060.01
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix20.80.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.037
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix154.2

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.0
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen0.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.029
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen0.0

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.00.00.0040.0
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen0.00.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.061
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen0.0

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0150.0180.0260.031
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen0.00.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0060.0250.0230.009
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen0.00.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.00.0140.00.004
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen0.00.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.01
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTen0.0

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.146
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree100.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.142
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree97.3

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.1550.1560.1540.155
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree106.20.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.028
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree19.2

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.1840.1840.1830.181
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree126.00.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.2130.2230.2230.232
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree145.90.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.0570.0580.0590.06
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree39.00.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.158
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree108.2

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.318
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo100.0

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.123
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo38.7

wrb:CommercialAutomobileInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.2160.2160.2170.216
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo67.90.00.00.0

wrb:MonolineExcessProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value0.039
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo12.3

wrb:OtherLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.1440.1440.1410.14
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo45.30.00.00.0

wrb:ProfessionalLiabilityInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.2160.2270.2390.261
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo67.90.00.00.0

wrb:ShorttailInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value0.3090.2980.2910.285
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo97.20.00.00.0

wrb:WorkersCompensationInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-31
Value0.287
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo90.3

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet



Period End2019-12-312018-12-312017-12-312016-12-31
Value11227108111064710229
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet100.0100.0100.0100.0

us-gaap:ProductOrService

us-gaap:PropertyInsuranceProductLine



Period End2019-12-312018-12-312017-12-312016-12-31
Value186189230139
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.71.82.21.4

wrb:CasualtyInsuranceProductLine



Period End2019-12-312018-12-312017-12-312016-12-31
Value1556151216321285
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet13.914.015.312.6

wrb:CommercialAutomobileInsuranceProductLine



Period End2019-12-312018-12-312017-12-312016-12-31
Value697633569559
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet6.25.95.35.5

wrb:MonolineExcessProductLine



Period End2019-12-31
Value1280
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet11.4

wrb:OtherLiabilityInsuranceProductLine



Period End2019-12-312018-12-312017-12-312016-12-31
Value3998369634693290
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet35.634.232.632.2

wrb:ProfessionalLiabilityInsuranceProductLine



Period End2019-12-312018-12-312017-12-312016-12-31
Value1034904847737
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet9.28.48.07.2

wrb:ShorttailInsuranceProductLine



Period End2019-12-312018-12-312017-12-312016-12-31
Value510531565608
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet4.54.95.35.9

wrb:WorkersCompensationInsuranceProductLine



Period End2019-12-31
Value1870
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet16.7

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:OtherInsuranceProductLine, wrb:InsuranceSegment



Period End2019-12-312018-12-312017-12-312016-12-31
Value92111164158
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet0.81.01.51.5

us-gaap:PropertyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment



Period End2019-12-31
Value186
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.7

wrb:CasualtyInsuranceProductLine, wrb:ReinsuranceandMonolineExcessSegment