MCY


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

Table of contents



us-gaap:CommonStockValue
us-gaap:ConsolidatedEntities

us-gaap:CommonStockSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:BenefitsLossesAndExpenses

us-gaap:CostOfGoodsAndServicesSold

us-gaap:DeferredPolicyAcquisitionCostAmortizationExpense

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxesPaidNet

us-gaap:InterestExpense

us-gaap:InterestPaidNet

us-gaap:NetIncomeLoss
us-gaap:StatementEquityComponents

us-gaap:OtherIncome

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet
us-gaap:StatementBusinessSegments

us-gaap:PremiumsEarnedNet
us-gaap:ProductOrService
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments

us-gaap:RealizedInvestmentGainsLosses

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax

us-gaap:Revenues

us-gaap:Assets
us-gaap:ConsolidatedEntities

us-gaap:Liabilities
us-gaap:ConsolidatedEntities

us-gaap:LiabilitiesAndStockholdersEquity
us-gaap:ConsolidatedEntities

us-gaap:Cash
us-gaap:ConsolidatedEntities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
us-gaap:ConsolidatedEntities

us-gaap:ShortTermInvestments
us-gaap:ConsolidatedEntities
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument

us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AmortizationOfIntangibleAssets

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsNet

us-gaap:OperatingLeaseRightOfUseAsset

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

us-gaap:OtherAssets
us-gaap:ConsolidatedEntities

us-gaap:AccruedIncomeTaxesCurrent

us-gaap:LongTermDebt

us-gaap:DeferredIncomeTaxLiabilitiesNet
us-gaap:ConsolidatedEntities

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:OperatingLeaseLiability

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

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

us-gaap:CommonStockValue
us-gaap:ConsolidatedEntities

us-gaap:RetainedEarningsAccumulatedDeficit
us-gaap:ConsolidatedEntities
us-gaap:StatementEquityComponents
us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss
us-gaap:StatementEquityComponents

us-gaap:ShareBasedCompensation

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:PaymentsToAcquireProductiveAssets

us-gaap:NetCashProvidedByUsedInFinancingActivities
us-gaap:AssetsSoldUnderAgreementsToRepurchase, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentInterestRateStatedPercentage

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

us-gaap:DeferredTaxLiabilities

us-gaap:UnrecognizedTaxBenefits

mcy:PaymentstoAcquireEquitySecuritiesFVNI

mcy:PercentageOfUnadjustedFairValueObtained

mcy:PremiumReceivableAllowanceforCreditLossWriteoff

mcy:ProceedsFromEquitySecuritiesCallsOfEquitySecuritiesAvailableForSale

mcy:ProceedsfromSaleofEquitySecuritiesFVNI
us-gaap:StatementEquityComponents
mcy:StockOptionsExercisedDecreaseForTaxWithholdingObligation

us-gaap:AdvertisingExpense
us-gaap:StatementBusinessSegments
us-gaap:AssumedPremiumsEarned
us-gaap:StatementBusinessSegments
us-gaap:AssumedPremiumsWritten

us-gaap:CapitalizedContractCostAmortization

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect

us-gaap:CededPremiumsEarned
us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments
us-gaap:CededPremiumsWritten

us-gaap:CommonStockDividendsPerShareDeclared

us-gaap:DepreciationAmortizationAndAccretionNet
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation
us-gaap:DerivativeGainLossOnDerivativeNet
us-gaap:HedgingDesignation
us-gaap:StatementBusinessSegments
us-gaap:DirectPremiumsEarned

us-gaap:DirectPremiumsWritten
us-gaap:ProductOrService
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments
us-gaap:StatementEquityComponents
us-gaap:DividendsCommonStockCash
us-gaap:FinancialInstrument
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
us-gaap:FinancialInstrument
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3

us-gaap:FairValueOptionChangesInFairValueGainLoss1
us-gaap:InvestmentType

us-gaap:FinanceLeasePrincipalPayments

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInBrokerDealerRelatedReceivablesPayablesNet

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes

us-gaap:IncreaseDecreaseInDeferredPolicyAcquisitionCosts

us-gaap:IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities

us-gaap:IncreaseDecreaseInPremiumsReceivable

us-gaap:IncreaseDecreaseInReinsuranceRecoverable

us-gaap:IncreaseDecreaseInUnearnedPremiums

us-gaap:InterestAndDividendIncomeOperating

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1
us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1

us-gaap:LossFromCatastrophes

us-gaap:OtherCostAndExpenseOperating

us-gaap:OtherUnderwritingExpense
us-gaap:StatementBusinessSegments

us-gaap:PaymentsForLossesAndLossAdjustmentExpense

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsForProceedsFromShortTermInvestments

us-gaap:PaymentsOfOrdinaryDividends

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt

us-gaap:PremiumReceivableCreditLossExpenseReversal

us-gaap:PremiumsReceivableAllowanceForDoubtfulAccountsRecoveries
us-gaap:StatementBusinessSegments
us-gaap:PremiumsWrittenNet

us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt

us-gaap:ProceedsFromStockOptionsExercised

us-gaap:ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded

us-gaap:ReinsuranceRecoverableCreditLossExpenseReversal

us-gaap:ReinsuranceRetentionPolicyAmountRetained

us-gaap:ReinsuranceRetentionPolicyReinsuredRiskPercentage

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense

us-gaap:UnderwritingIncomeLoss
us-gaap:StatementBusinessSegments

us-gaap:UnrecognizedTaxBenefitsPeriodIncreaseDecrease

dei:EntityCommonStockSharesOutstanding

mcy:AmortizedCostOnFixedMaturityTradingInvestments

mcy:CostEquitySecurityTradingInvestments
us-gaap:ConsolidatedEntities

mcy:CostShortTermInvestments
us-gaap:ConsolidatedEntities

mcy:DeferredTaxLiabilitiesAcquisitionCosts

mcy:DeferredTaxLiabilitiesTaxAmortizationInExcessOfBookAmortization

mcy:DeferredTaxLiabilitiesUndistributedInsuranceSubsidiaries
us-gaap:ConsolidatedEntities
mcy:IncomeTaxPayableDueToAffiliate
us-gaap:ConsolidatedEntities
mcy:IncomeTaxReceivableDueFromAffiliate

mcy:LesseeOperatingLeaseNotYetCommencedAmount
us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent
mcy:LiabilityforCatastropheClaimsNetofReinsuranceBenefits

mcy:NotesPayablePrincipal

mcy:ReinsuranceRecoverablesNet

mcy:ReissuanceRecoverable
us-gaap:CumulativeEffectPeriodOfAdoption

mcy:SecurityDepositsByInsuranceCompanies

mcy:TradingSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue

mcy:TradingSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue

mcy:TradingSecuritiesDebtMaturitiesAfterTenYearsFairValue

mcy:TradingSecuritiesDebtMaturitiesWithinOneYearFairValue

mcy:TwoPrivateEquityFundsUsingNAV

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent

us-gaap:AccountsReceivableGross

us-gaap:AccruedInvestmentIncomeReceivable
us-gaap:ConsolidatedEntities
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:AlternativeInvestment
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:AssetsFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency

us-gaap:CapitalizedContractCostAccumulatedAmortization

us-gaap:CapitalizedContractCostNet

us-gaap:ContractWithCustomerRefundLiability
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentFaceAmount

us-gaap:DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredPolicyAcquisitionCosts

us-gaap:DeferredPolicyAcquisitionCostsAndValueOfBusinessAcquired

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsOther

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve

us-gaap:DeferredTaxLiabilitiesOther

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment

us-gaap:DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities
us-gaap:FinancialInstrument
us-gaap:DerivativeFairValueOfDerivativeAsset
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:DerivativeFairValueOfDerivativeLiability
us-gaap:HedgingDesignation
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument
us-gaap:DerivativeLiabilities
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument
us-gaap:FinancialInstrument
us-gaap:ConsolidatedEntities
us-gaap:DueFromAffiliates
us-gaap:ConsolidatedEntities
us-gaap:DueToAffiliateCurrentAndNoncurrent

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
us-gaap:PlanName

us-gaap:FinanceLeaseLiability

us-gaap:FinanceLeaseLiabilityPaymentsDue

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFive

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount

us-gaap:FinanceLeaseRightOfUseAsset
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FinancialLiabilitiesFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType
us-gaap:FairValueByMeasurementFrequency, us-gaap:OptionIndexedToIssuersEquityType

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo

us-gaap:IncomeTaxExaminationPenaltiesAndInterestAccrued

us-gaap:IncomeTaxesReceivable

us-gaap:IntangibleAssetsGrossExcludingGoodwill
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:Investments
us-gaap:ConsolidatedEntities
us-gaap:FinancialInstrument
us-gaap:InvestmentsFairValueDisclosure
us-gaap:ConsolidatedEntities
us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesFairValueDisclosure

us-gaap:LesseeFinanceLeaseDiscountRate

us-gaap:LesseeOperatingLeaseDiscountRate

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths
us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent
us-gaap:LiabilityForCatastropheClaimsCarryingAmount

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpensePropertyCasualtyLiability

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet
us-gaap:AssetsSoldUnderAgreementsToRepurchase, us-gaap:CreditFacility
us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive

us-gaap:NotesPayable
us-gaap:ConsolidatedEntities
us-gaap:FinancialInstrument, us-gaap:LongtermDebtType
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType
us-gaap:NotesPayableFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType
us-gaap:FinancialInstrument, us-gaap:LongtermDebtType

us-gaap:OtherLiabilities
us-gaap:ConsolidatedEntities

us-gaap:OtherReceivables

us-gaap:OtherShortTermInvestments

us-gaap:PremiumsAndOtherReceivablesNet

us-gaap:PremiumsReceivableAllowanceForDoubtfulAccounts
us-gaap:CumulativeEffectPeriodOfAdoption

us-gaap:PremiumsReceivableAtCarryingValue

us-gaap:PremiumsReceivableGross

us-gaap:RatioOfIndebtednessToNetCapital1
us-gaap:Range, us-gaap:AssetsSoldUnderAgreementsToRepurchase, us-gaap:CreditFacility

us-gaap:ReinsuranceReceivablesCaseBasis

us-gaap:ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments
us-gaap:ProductOrService

us-gaap:ReinsuranceRecoverablesAllowance
us-gaap:CumulativeEffectPeriodOfAdoption

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
us-gaap:AwardType
us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet
us-gaap:ProductOrService, us-gaap:ShortdurationInsuranceContractsAccidentYear
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo
us-gaap:ProductOrService, us-gaap:ShortdurationInsuranceContractsAccidentYear
us-gaap:ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet
us-gaap:ProductOrService, us-gaap:ShortdurationInsuranceContractsAccidentYear

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet
us-gaap:ProductOrService
us-gaap:ProductOrService
us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimAdjustmentExpenseAggregateReconcilingItems

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimAdjustmentExpenseOtherReconcilingItem

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense
us-gaap:ProductOrService, us-gaap:ShortdurationInsuranceContractsAccidentYear
us-gaap:ShortdurationInsuranceContractsNumberOfReportedClaims

us-gaap:StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithoutRegulatoryApproval

us-gaap:StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount
us-gaap:FinancialInstrument

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost
us-gaap:FinancialInstrument

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue
us-gaap:FinancialInstrument
us-gaap:ConsolidatedEntities
us-gaap:TaxesPayableCurrentAndNoncurrent
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FinancialInstrument
us-gaap:TradingSecurities

us-gaap:TradingSecuritiesDebt
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument

us-gaap:UnamortizedDebtIssuanceExpense

us-gaap:UnearnedPremiums

us-gaap:UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate

Plots across concepts


IncomeStatement
Net Income Loss
Expenses
Cost Of Goods And Services Sold
Balance Sheet
Intangible Assets Net Excluding Goodwill
Assets
Other Assets
Current Assets
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents
NonCurrent Assets
Intangible Assets Net Excluding Goodwill
PropertyPlantAndEquipmentNet
Property Plant And Equipment Net
Liabilities
Operating Lease Liability
Noncurrent Liabilities
Deferred Income Tax Liabilities Net
Stockholders Equity
Common Stock Value
Per Share
Common Stock Dividends Per Share Declared
CashFlow
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInOperatingActivities
Share Based Compensation
NetCashProvidedByUsedInInvestingActivities
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInFinancingActivities
Net Cash Provided By Used In Financing Activities
Shares
Common Stock Shares Outstanding
LesseeOperatingLeaseLiabilityPaymentsDue
Lessee Operating Lease Liability Undiscounted Excess Amount
FiniteLivedIntangibleAssets
Finite Lived Intangible Assets Net

Tables

  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:CommonStockValue ████████████████▇▇▇▇▇▇▆▆▆▅▅▄▃▃▃▃▃▂▂▂▂▂▂▁▁▁▁98.87298.83798.9798.93498.89898.86398.82898.68398.64798.49598.02697.96797.58697.54697.52397.52396.56596.54495.52994.93794.00693.97190.98591.02890.99390.10588.70583.66681.78481.7181.59181.10980.85779.40979.3879.06379.01677.83376.63475.3775.08674.82274.188NANANA
us-gaap:CommonStockSharesOutstanding ▄▄55.37155.371NANANA55.35855.35855.35555.35555.3555.3455.3455.33255.33255.33255.33255.31155.31155.28955.27155.25455.25455.16455.16455.16455.14755.12155.02154.97954.97854.97554.9654.95954.92254.92254.91154.91154.8830.0548560.0548270.05482254.81854.803NANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding █▁55.37655.372NA55.35855.35855.358NA55.36655.36355.348NA55.34155.33555.335NA55.33455.32355.312NA55.32855.32255.208NA55.17855.17955.159NA55.01454.98954.986NA54.97354.94154.935NA54.92554.89554.908NA54.82654.83754.831NA54.81754.83354.805
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic █▁55.37155.361NA55.35855.35855.358NA55.35555.35355.341NA55.33755.33255.332NA55.32455.31155.297NA55.25955.25455.201NA55.16455.1655.139NA55.00254.97854.977NA54.95954.94154.922NA54.91154.89554.877NA54.82654.8254.809NA54.79554.78854.783
us-gaap:EarningsPerShareBasic ▆▆▇▆█▁▄▅▅▆▂▅▅▃▄▅▅▄▃▄▅▄▄▄▄▄▃▄▅▅▄▄▃▅▃▅▄▅▅▄▅▅▃▆▄▅1.971.933.012.154.12-2.510.571.251.52.46-1.481.061.09-0.770.360.840.930.49-0.470.490.880.420.420.280.170.47-0.380.571.731.320.280.72-0.171.21-0.321.21-0.11.341.45-0.071.041.06-0.431.770.331.12
us-gaap:EarningsPerShareDiluted ▆▆▇▆█▁▄▅▅▆▂▅▅▃▄▅▅▄▃▄▅▄▄▄▄▄▃▄▅▅▄▄▃▅▃▅▄▅▅▄▅▅▃▆▄▅1.971.933.012.154.12-2.510.571.251.52.45-1.481.061.09-0.770.360.840.930.49-0.470.490.880.420.420.280.170.47-0.380.571.731.320.280.72-0.171.21-0.321.21-0.11.341.45-0.071.041.06-0.431.770.321.12
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:BenefitsLossesAndExpenses ▆▆▆▆▃▇█▇▆▆▇▅▅▆▆▅▄▅▄▄▅▅▄▃▃▃▄▂▂▂▃▂▂▂▃▁▂▁▁▁▁▁▃▁▁▁883.374860.675864.474852.143720.377889.016959.528906.455877.892850.574931.066824.525812.145842.883847.767800.11784.095816.905788.868776.537793.668797.886762.238740.146721.66714.689749.972682.867670.583660.926698.386673.874667.526649.159720.373640.448666.558620.681638.761633.859630.934628.632705.736630.911638.301618.547
us-gaap:CostOfGoodsAndServicesSold ▆█▄▄▆▅▃▂▃▃▄▁▃▄▂3.23.72.82.83.23.02.72.52.72.72.92.22.62.82.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:DeferredPolicyAcquisitionCostAmortizationExpense ▆██▇▆▇▇▆▆▆▆▅▅▅▄▄▄▅▅▄▄▅▄▃▄▄▃▃▃▃▃▃▂▂▂▂▁▁▁▂▂▂▂▂▂▃150.984164.43164.184157.365149.706156.533154.114150.929148.629148.413147.365142.295141.52140.984138.622136.29137.839142.6140.845140.203139.9141.56137.363132.881135.14133.847132.244131.09133.06129.814128.511126.891126.393123.722120.726121.906117.726117.43116.072121.016122.829121.804125.257125.001126.325128.982
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments ▆▆▇▆█▁▄▅▅▆▂▅▅▃▄▅▅▄▃▄▅▄▄▄▄▄▃▄▆▅▄▅▃▅▃▅▃▅▅▃▅▅▃▆▄▅135.401132.421207.11146.631285.466-180.70528.46580.84101.595167.169-114.44870.373.2-59.6999.48758.24768.830.6-51.2731.62564.33526.03423.9312.2674.51129.859-28.16137.12136.436102.0311.26854.793-24.95990.994-39.16191.33-18.853101.994110.693-18.11875.61376.911-50.097135.83915.35881.29
us-gaap:IncomeTaxExpenseBenefit ▆▆▇▆█▁▄▅▅▆▂▅▅▃▃▅▅▄▂▄▅▄▄▄▄▄▃▄▇▆▄▅▃▆▂▆▃▆▆▃▅▅▂▇▄▅26.2225.42640.36627.77457.255-41.501-3.22311.55818.34531.302-32.56911.70813.066-17.092-10.29211.76217.1193.619-25.1884.69515.4622.7110.525-3.003-5.1283.694-7.2055.82441.47629.381-4.10815.223-15.69524.533-21.77925.129-13.58928.63831.224-14.33618.36218.685-26.4538.99-2.45920.111
us-gaap:IncomeTaxesPaidNet NANA15.20617.36220.0910.0-15.7421.2-0.0580.036-0.211-11.4750.703-0.00610.868NANA1.051NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:InterestExpense █████████████████▅▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▂▃▃▄▄▃▄▃4.2354.3434.2624.2624.2684.2564.2564.2574.2664.2564.2214.2574.2564.34.2684.24.2292.51.0781.0120.960.950.8960.7850.7690.750.7370.7070.6880.5050.3960.3380.2120.3140.3670.3880.3780.410.8991.2861.6691.6951.7031.6331.8511.619
us-gaap:InterestPaidNet ▁█▁█▁█▁█▁█▁0.0288.2750.0268.2750.0298.2690.0198.270.0298.2680.019NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLoss ▆▆▇▆█▁▄▅▅▆▂▅▅▃▄▅▅▄▃▄▅▄▄▄▄▄▃▄▅▅▄▄▃▅▃▅▄▅▅▄▅▅▃▅▄▅109.181106.995166.743118.857228.211-139.20431.68869.28283.25135.867-81.87958.57860.2-42.60719.77946.48551.63326.98-26.08226.9348.87323.323.40515.279.63926.165-20.95631.29694.9672.64915.37639.57-9.26466.461-17.38266.201-5.26473.35679.469-3.78257.25158.226-23.64796.84917.81761.179
us-gaap:OtherIncome ▃▅▂▄▂▄▃▄▃▃▃▄▄▃▃█▃▃▃▄▃▃▃▃▃▃▃▃▃▃▃▄▄▃▄▄▄▄▁▅▇▅▅▃▃▂2.1973.2041.4772.8941.3532.5621.8412.6032.352.32.1672.42.42.3252.275.42.1242.1051.8942.4061.8872.1232.0882.2812.2762.2662.0052.2752.092.3012.1992.6852.5212.3332.3842.5322.5442.7140.6633.5084.4433.273.0631.7612.181.293
us-gaap:PolicyholderBenefitsAndClaimsIncurredNet ▆▅▆▅▂▆█▇▆▆█▅▅▆▆▅▅▅▅▄▅▅▄▄▃▃▃▂▂▂▃▂▂▂▄▂▃▁▂▂▁▁▃▁▁▁657.228626.344629.716618.657495.3651.67738.103680.928656.577630.416724.939614.069605.5632.234654.3595.29588.595606.665589.638576.3595.086594.082564.189545.692521.214514.4533.951492.525483.043476.603516.166492.558486.906467.06546.352467.929497.251449.916472.876458.53451.338446.461514.969440.566439.609430.622
us-gaap:PremiumsEarnedNet ███▇▅███▇▇▇▆▆▅▅▅▅▅▅▅▄▄▄▄▃▃▃▃▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁926.82915.922921.86899.304811.898922.574925.384915.012888.776870.2868.233858.1834.0808.1806.796801.2797.7789.8794.517790.9779.3767.1760.094745.52731.546720.737709.368705.237697.889683.701680.892678.913675.787662.595655.777646.084637.247635.812641.613643.626642.331638.487640.796642.558642.717640.614
us-gaap:RealizedInvestmentGainsLosses ▆▆▇▆█▁▆▆▆▇▄▅▆▄▆▆▆▆▄▅▆▆▅▅▅▅▅▅▇▆▅▆▄▆▅▆▅▆▇▄▆▆▅▇▅▆58.80541.691114.18964.436158.426-251.3225.06733.32453.329111.074-85.12-3.9114.3-58.73517.31620.71821.15624.5-89.255-15.545.38125.057-8.2-26.286-39.348-9.961-21.6-20.08976.1946.712-4.26916.212-67.41544.05-12.27649.752-23.75952.66372.862-66.91923.76428.69-23.68186.439-27.71322.044
us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax ▅█▃▃▃▄▂▃▃▃▁▂▂▃▁▂5.06.34.34.54.54.73.84.24.24.23.74.04.04.33.63.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:Revenues ▇▇█▇▇▂▇▇▇▇▄▅▅▄▅▅▅▅▃▄▅▄▄▃▃▃▃▃▄▃▂▃▁▃▂▃▁▃▃▁▂▂▂▃▂▂1018.775993.0961071.583998.7741005.843708.311987.993987.295979.4871017.743816.618894.811885.391783.184857.254858.357852.847847.504737.598808.162858.003823.92786.168752.413726.171744.548721.811719.987807.019762.956709.654728.667642.567740.153681.212731.778647.705722.675749.454615.741706.547705.543655.639766.75653.659699.837
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:Assets ██▇▇▆▅▆▆▅▅▅▄▄▄▄▄▃▃▃▃▃▃▂▃▂▂▂▂▂▂▂▂▁▂▁▁▁▁▁▁▁▁▁6696.9486554.1546328.2466145.7885916.7375716.8985889.1575873.2425716.5185606.725433.7295313.0375204.4715132.7875101.3235025.5994938.9834863.9894788.7184801.2724722.0484692.0634628.6454646.5794586.4844618.0574600.2894609.0064562.44476.1194315.1814340.4564231.824272.1664189.6864210.914120.4334136.7794070.0064096.6174246.5154208.5754203.364NANANA
us-gaap:Liabilities ██▇▇▇▇▇▇▆▆▆▅▅▅▄▄▄▄▄▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁▂▂▂4518.3174449.7174295.6494244.9564099.9224093.4544089.6554070.6983948.5563887.4263816.0453578.8073494.6133448.5663339.9363249.4083175.7913118.023036.3162985.8152900.022884.6852807.762817.082738.7412748.0932724.8432684.3662638.7372614.3132492.6952500.3012397.9522396.822347.1892317.0772259.7022238.2192212.5232287.132400.9132387.6982408.549NANANA
us-gaap:LiabilitiesAndStockholdersEquity ██▇▇▆▅▆▆▅▅▅▄▄▄▄▄▃▃▃▃▃▃▂▃▂▂▂▂▂▂▂▂▁▂▁▁▁▁▁▁▁▁▁6696.9486554.1546328.2466145.7885916.7375716.8985889.1575873.2425716.5185606.725433.7295313.0375204.4715132.7875101.3235025.5994938.9834863.9894788.7184801.2724722.0484692.0634628.6454646.5794586.4844618.0574600.2894609.0064562.44476.1194315.1814340.4564231.824272.1664189.6864210.914120.4334136.7794070.0064096.6174246.5154208.5754203.364NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:Cash █▇▇▆▄▄▅▆▄▅▆▄▄▅▅▅▄▃▃▃▃▃▄▅▅▃▅▅▄▄▄▄▂▂▁▂▁▂▃▃▆▇▂▂▃▄378.615338.43348.479322.129262.153252.836294.398315.37240.32270.105314.291261.68243.751290.07291.413284.639261.425236.584220.318229.857233.281235.109264.221295.184274.782234.576289.907279.681258.473238.832266.508250.061180.331185.042158.183188.174160.487204.701211.393209.763305.057334.29181.388174.794219.466242.511
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents █▆▆▅▂▂▄▅▁▃▅378.615338.43348.479322.129262.153252.836294.398315.37240.32270.105314.291NANANA291.413NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ShortTermInvestments NANA375.609253.842335.634237.52494.135421.574362.197367.351253.299262.806270.584245.198302.711366.402280.045260.705375.68206.851181.304155.185185.277162.835153.548173.604372.542291.325229.412303.56315.776251.449165.52152.081294.653221.083179.326227.196236.444248.857138.671111.618143.371NANANA
 us-gaap:ShortTermInvestments us-gaap:ConsolidatedEntities srt:ParentCompanyNANA4.269NANANA29.356NANANA3.166NANANA21.231NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByFairValueHierarchyLevel,us-gaap:FairValueByMeasurementFrequency us-gaap:FairValueInputsLevel1,us-gaap:FairValueMeasurementsRecurring▆█▅▂▄▁▇▅▄▄▂403.461520.769370.68238.837322.176189.1464.055384.094322.57347.482236.515NANANA300.691NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByFairValueHierarchyLevel,us-gaap:FairValueByMeasurementFrequency us-gaap:FairValueInputsLevel2,us-gaap:FairValueMeasurementsRecurring▁▅▁▃▂█▅▆▇▃▃5.0127.3354.92915.00513.45848.4230.0837.4839.62719.86916.784NANANA2.02NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByFairValueHierarchyLevel,us-gaap:FairValueByMeasurementFrequency,us-gaap:FinancialInstrument us-gaap:FairValueInputsLevel1,us-gaap:FairValueMeasurementsRecurring,mcy:OtherShortTermInvestments█▇▁0.010.0090.005NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByFairValueHierarchyLevel,us-gaap:FairValueByMeasurementFrequency,us-gaap:FinancialInstrument us-gaap:FairValueInputsLevel1,us-gaap:FairValueMeasurementsRecurring,us-gaap:MoneyMarketFunds▆█▄▂▄▁▇▅▃▄▁403.451520.76348.676238.837322.176188.574461.233381.768289.769314.681205.043NANANA270.693NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByFairValueHierarchyLevel,us-gaap:FairValueByMeasurementFrequency,us-gaap:FinancialInstrument us-gaap:FairValueInputsLevel1,us-gaap:FairValueMeasurementsRecurring,us-gaap:ShortTermDebtNANA21.999NA0.00.5262.8222.32632.80132.80131.472NANANA29.998NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByFairValueHierarchyLevel,us-gaap:FairValueByMeasurementFrequency,us-gaap:FinancialInstrument us-gaap:FairValueInputsLevel2,us-gaap:FairValueMeasurementsRecurring,us-gaap:ShortTermDebt▁▅▁▃▂█▅▆▇▃▃5.0127.3354.92915.00513.45848.4230.0837.4839.62719.86916.784NANANA2.02NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByMeasurementFrequency us-gaap:FairValueMeasurementsRecurring▅█▄▁▃▁▇▅▄▄▁408.471548.104375.609253.842335.634237.52494.135421.574362.197367.351253.299NANANA302.711NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByMeasurementFrequency,us-gaap:FinancialInstrument us-gaap:FairValueMeasurementsRecurring,mcy:OtherShortTermInvestments█▇▁0.010.0090.005NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByMeasurementFrequency,us-gaap:FinancialInstrument us-gaap:FairValueMeasurementsRecurring,us-gaap:MoneyMarketFunds▆█▄▂▄▁▇▅▃▄▁403.451520.76348.676238.837322.176188.574461.233381.768289.769314.681205.043NANANA270.693NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ShortTermInvestments us-gaap:FairValueByMeasurementFrequency,us-gaap:FinancialInstrument us-gaap:FairValueMeasurementsRecurring,us-gaap:ShortTermDebt▁▃▃▂▂▆▄▅█▆▅5.0127.33526.92815.00513.45848.94632.90239.80672.42852.6748.256NANANA32.018NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:PropertyPlantAndEquipmentGross NANA464.946NANANA481.046NANANA512.292NANANA485.746NANANA475.339NANANA456.323NANANA436.288NANANA419.279NANANA401.354NANANA396.945NANANA388.871NANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:BuildingAndBuildingImprovementsNANA139.274NANANA140.567NANANA138.238NANANA136.827NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:FurnitureAndFixturesNANA46.45NANANA70.355NANANA123.021NANANA118.647NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:LandNANA18.152NANANA18.152NANANA18.144NANANA18.152NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:LeaseholdImprovementsNANA7.004NANANA7.547NANANA9.986NANANA9.632NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:SoftwareDevelopmentNANA254.066NANANA244.425NANANA222.903NANANA202.488NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment ▂▂▁▁▂▄▃██▇▇▇▆▆▆▅▅▄▄▄▃296.747292.321286.023280.032294.479318.274312.06372.876369.817364.015359.269354.967350.007345.263340.523335.477330.219324.551319.429314.29309.011NA299.192NANANA277.312NANANA262.563NANANA239.414NANANA219.185NANANA192.366NANANA
us-gaap:AmortizationOfIntangibleAssets ▁▁▁▁▁▁▆▆▆▆▇▇▇▇▇▆▆▆▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇█▇▇▇███0.30.30.30.20.20.21.31.31.31.31.41.41.41.41.41.31.31.31.51.51.51.51.51.51.51.51.51.51.51.51.51.51.51.51.61.51.51.51.61.61.6NANANANANA
us-gaap:PropertyPlantAndEquipmentNet ▆▆▆▅▅▄▄▄▃▃▂▂▂▁▁▁▂▂▃▃▃▃▃▃▃▃▃▃▃▃▃▂▂▃▃▄▄▅▅▆▆▇█181.969178.393178.923174.924172.015169.287168.986168.294162.65155.844153.023149.719148.214145.853145.223144.478155.264155.515155.91155.73157.164158.412157.131157.605157.455156.989158.976160.134157.428155.954156.716154.467154.884158.284161.94165.169168.696172.422177.76179.977185.075190.325196.505NANANA
us-gaap:Goodwill ▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁████████42.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.79642.8542.8542.8542.8542.8542.8542.8542.85NANANA
us-gaap:IntangibleAssetsNetExcludingGoodwill ▁▁▁▁▁▁▁▁▁▂▂▂▂▂▃▃▃▃▃▃▄▄▄▄▄▅▅▅▅▅▅▆▆▆▆▆▇▇▇▇███10.78911.05511.3229.93910.16410.410.63611.90313.1714.43715.53416.90118.25619.62220.72821.61122.94924.28725.62527.14428.66330.18231.70232.53834.03335.52835.62337.11838.61340.10841.60343.09844.59346.0947.58949.10550.65352.20153.74955.29856.8758.48660.124NANANA
us-gaap:FiniteLivedIntangibleAssetsNet ▅▇█▁9.3899.6559.9228.539NANANANANANANANANANANANANANANANANANANANANANA35.62337.11838.61340.10841.60343.09844.59346.0947.58949.10550.65352.20153.74955.29856.87NA60.124NANANA
us-gaap:OperatingLeaseRightOfUseAsset ▇▇▇▇█████▇▁36.89638.88940.55441.07543.20745.12644.90945.83444.43241.2750.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:EquitySecuritiesFvNi █▇▇▇▅▃▅▄▃▃▁▄▃870.556810.602803.851809.591739.163619.684724.751657.135645.407616.5529.631688.387614.336NA537.24NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:AccruedIncomeTaxesCurrent NA34.23810.4266.4016.8535.510.0NANANANANANANANANANANANANANANANANANANA0.07.79224.4764.96111.85626.3242.3954.7260.00.00.05.2920.06715.5715.863NA0.0NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:LongTermDebt NANA375.0NANANANANANANANANANANANANANANANANANANANANANANANANANANA120.0NANANA120.0NANANANANANANANANANANA
us-gaap:DeferredIncomeTaxLiabilitiesNet █▇▆▄▂▁▅▄▃▂▁▂▂▂▄▃▃▂▂52.61642.74741.13219.9969.1310.027.96421.06815.6546.1660.07.1468.8077.25122.93213.17312.7068.6469.962NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo NANA12.739NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree NANA8.095NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour NANA4.388NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive NANA2.832NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive NANA2.985NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest █▇▆▅▃▁▃▃▃▂▁▂▂▂▃▃▃▃▃▃▄▃▄▄▄▄▄▅▅▄▄▄▄▄▄▄▄▅▄▃▄▄▃2178.6312104.4372032.5971900.8321816.8151623.4441799.5021802.5441767.9621719.2941617.6841734.231709.8581684.2211761.3871776.1911763.1921745.9691752.4021815.4571822.0281807.3781820.8851829.4991847.7431869.9641875.4461924.641923.6631861.8061822.4861840.1551833.8681875.3461842.4971893.8331860.7311898.561857.4831809.4871845.6021820.8771794.815NANANA
us-gaap:CommonStockValue ████████████████▇▇▇▇▇▇▆▆▆▅▅▄▃▃▃▃▃▂▂▂▂▂▂▁▁▁▁98.87298.83798.9798.93498.89898.86398.82898.68398.64798.49598.02697.96797.58697.54697.52397.52396.56596.54495.52994.93794.00693.97190.98591.02890.99390.10588.70583.66681.78481.7181.59181.10980.85779.40979.3879.06379.01677.83376.63475.3775.08674.82274.188NANANA
us-gaap:RetainedEarningsAccumulatedDeficit █▇▆▅▃▁▃▃▃▂▁▂▂▂▃▃▃▃▃▃▄▃▄▄▄▄▄▅▅▄▄▄▄▄▄▅▄▅▄▄▄▄▄2079.7592005.61933.6271801.8981717.9171524.5811700.6741703.8611669.3151620.7991519.6581636.2631612.2721586.6751663.8641678.6681666.6271649.4251656.8731717.3731724.7111710.0961721.031731.8271750.6211775.0471782.9371837.9281840.4691779.3221740.4841758.9181753.0111795.9371763.1171814.1351781.431820.1891780.3111734.3041770.9811746.6241721.289NANANA
 us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue us-gaap:StatementEquityComponents us-gaap:CommonStock▆▆▇▇▆▆▆▇▇▁███▃0.0350.0350.0360.0360.0350.0350.0350.0360.0360.0160.0410.0410.040.023NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▇█▇█▇▅▅▇▅█▄▆▅▄▄▅▅▄▄▅▃▃▃▄▄▂▃▄▄▃▃▄▃▄▃▄▂▃▁▄▃▃▁▃▂▃142.722174.519162.364183.669162.43797.146106.085147.9790.936174.68758.239141.12105.72478.35164.94101.72100.52274.22377.922107.86656.00645.67941.53775.51861.73711.45247.03871.10878.94349.44640.08773.25938.2658.19834.73263.94914.69834.683-12.22777.69457.48235.576-7.64347.3819.16332.881
us-gaap:NetCashProvidedByUsedInInvestingActivities ▃▂▃▃▂▃▃▄▃▁▅▃▂▄▄▄▄▃▃▃▄▄▄▄▅▄▅▄▄▂▅▅▅▅▄▅▄▅▆▅▄█▆▄▅▆-67.52-149.368-100.391-88.817-118.245-103.833-92.292-38.184-86.125-184.629.08-88.944-117.46-45.112-23.583-45.053-40.621-76.34-83.887-77.819-23.577-41.437-38.218-21.05311.682-34.093-7.203-37.909-25.528-123.3950.161-9.929-10.8852.302-31.451-2.766-26.527-9.00144.162-15.269-53.977149.69947.005-59.956-10.18356.234
us-gaap:NetCashProvidedByUsedInFinancingActivities ▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▇▆▅▅▅▅▅▅▅▅▆▅█▆▇▅▅▅▅▅▅▅▁▅▅▅▅▅▅-35.017-35.2-35.623-34.876-34.875-34.875-34.765-34.736-34.596-34.273-34.708-34.247-34.583-34.582-34.583-33.453-35.0618.383-3.574-33.471-34.257-33.354-34.282-34.063-33.213-32.69-29.609-11.991-33.77446.273-23.8016.4-32.086-33.641-33.272-33.496-32.385-32.374-30.305-157.719-32.738-32.373-32.768-32.096-32.025-32.109
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▇█▇█▇▅▅▇▅█▄▆▅▄▄▅▅▄▄▅▃▃▃▄▄▂▃▄▄▃▃▄▃▄▃▄▂▃▁▄▃▃▁▃▂▃142.722174.519162.364183.669162.43797.146106.085147.9790.936174.68758.239141.12105.72478.35164.94101.72100.52274.22377.922107.86656.00645.67941.53775.51861.73711.45247.03871.10878.94349.44640.08773.25938.2658.19834.73263.94914.69834.683-12.22777.69457.48235.576-7.64347.3819.16332.881
us-gaap:NetIncomeLoss ▆▆▇▆█▁▄▅▅▆▂▅▅▃▄▅▅▄▃▄▅▄▄▄▄▄▃▄▅▅▄▄▃▅▃▅▄▅▅▄▅▅▃▅▄▅109.181106.995166.743118.857228.211-139.20431.68869.28283.25135.867-81.87958.57860.2-42.60719.77946.48551.63326.98-26.08226.9348.87323.323.40515.279.63926.165-20.95631.29694.9672.64915.37639.57-9.26466.461-17.38266.201-5.26473.35679.469-3.78257.25158.226-23.64796.84917.81761.179
us-gaap:ShareBasedCompensation ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄█▄▄▁▇▅▆▅▆▆▅▅▅▅▄▄▄▅▄▅▅▅▅▅▄▅▅▅0.0350.0350.0360.0360.0350.0350.0350.0360.0360.0160.0410.040.0410.0230.00.0040.0210.0353.614-0.0310.036-3.4772.2620.551.3531.0431.3711.6720.6710.3980.7580.316-0.1290.029-0.6820.397-0.180.0950.2930.2920.1980.1160.0080.4080.1870.209
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▃▂▃▃▂▃▃▄▃▁▅▃▂▄▄▄▄▃▃▃▄▄▄▄▅▄▅▄▄▂▅▅▅▅▄▅▄▅▆▅▄█▆▄▅▆-67.52-149.368-100.391-88.817-118.245-103.833-92.292-38.184-86.125-184.629.08-88.944-117.46-45.112-23.583-45.053-40.621-76.34-83.887-77.819-23.577-41.437-38.218-21.05311.682-34.093-7.203-37.909-25.528-123.3950.161-9.929-10.8852.302-31.451-2.766-26.527-9.00144.162-15.269-53.977149.69947.005-59.956-10.18356.234
us-gaap:PaymentsToAcquireProductiveAssets ▆▅▆▆▆▆▅▇█▅▄▄▄▃▃▂▄▁▂▂▂▂▂▃▃▃▃▅▃▄▃▂▂▂▁▂▁▂▃▁▁▃▄▄▅▄9.8737.92910.1899.9759.48410.3058.26410.9512.4448.437.317.5016.9426.2065.1683.7187.1323.4254.1053.9394.3394.5963.7285.0865.375.9285.1578.6765.7596.4455.6884.6223.864.5012.9724.433.6234.1525.4663.0293.6285.9566.7436.8367.8767.431
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▇▆▅▅▅▅▅▅▅▅▆▅█▆▇▅▅▅▅▅▅▅▁▅▅▅▅▅▅-35.017-35.2-35.623-34.876-34.875-34.875-34.765-34.736-34.596-34.273-34.708-34.247-34.583-34.582-34.583-33.453-35.0618.383-3.574-33.471-34.257-33.354-34.282-34.063-33.213-32.69-29.609-11.991-33.77446.273-23.8016.4-32.086-33.641-33.272-33.496-32.385-32.374-30.305-157.719-32.738-32.373-32.768-32.096-32.025-32.109
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 us-gaap:DebtInstrumentInterestRateStatedPercentage us-gaap:AssetsSoldUnderAgreementsToRepurchase,us-gaap:LongtermDebtType mcy:UnsecuredNotesOne,us-gaap:UnsecuredDebtNANA4.4e-06NANANA4.4e-08NANANA4.4e-08NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value9898989898989898989898979797979796969594949390919090888381818181807979797977767575747472
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.51.51.61.61.71.71.71.71.71.81.81.81.91.91.91.92.02.02.02.02.02.02.02.02.02.01.91.81.81.81.91.91.91.91.91.91.91.91.91.81.81.81.81.7

us-gaap:CommonStockValue us-gaap:ConsolidatedEntities

srt:ParentCompany


Common
Period End2020-12-312019-12-312018-12-312017-12-31
Value98989897
Percentage of CommonStockValue100.0100.0100.0100.0
Percentage of Assets1.61.71.81.9
Percentage of Assets srt:ParentCompany4.14.54.94.5

Common Stock Shares Outstanding

us-gaap:CommonStockSharesOutstanding

us-gaap:CommonStockSharesOutstanding


Common
Period End2021-06-302021-03-312020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value55555555555555555555555555555555555555555555555555545454545454545454540.0548560.0548270.054822545454
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value5555555555555555555555555555555555555555555454545454545454545454545454
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value5555555555555555555555555555555555555555555454545454545454545454545454
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.971.933.012.154.12-2.510.571.251.52.46-1.481.061.09-0.770.360.840.930.49-0.470.490.880.420.420.280.170.47-0.380.571.731.320.280.72-0.171.21-0.321.21-0.11.341.45-0.071.041.06-0.431.770.331.12
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareDiluted


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.971.933.012.154.12-2.510.571.251.52.45-1.481.061.09-0.770.360.840.930.49-0.470.490.880.420.420.280.170.47-0.380.571.731.320.280.72-0.171.21-0.321.21-0.11.341.45-0.071.041.06-0.431.770.321.12
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Benefits Losses And Expenses

us-gaap:BenefitsLossesAndExpenses

us-gaap:BenefitsLossesAndExpenses


Benefits
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value883860864852720889959906877850931824812842847800784816788776793797762740721714749682670660698673667649720640666620638633630628705630638618
Percentage of BenefitsLossesAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating2853.92666.42538.32651.32108.52577.22687.72493.32506.02487.12974.72160.82334.72675.02752.52582.02457.92618.32589.82556.82526.52686.52367.32395.42276.72268.42338.82097.02173.72185.52265.12183.92107.52082.32039.21916.92104.51971.31861.41784.21752.21791.21990.21752.91750.01723.6

Cost Of Goods And Services Sold

us-gaap:CostOfGoodsAndServicesSold

us-gaap:CostOfGoodsAndServicesSold


Cost
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value3.23.72.82.83.23.02.72.52.72.72.92.22.62.82.4
Percentage of CostOfGoodsAndServicesSold100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating10.311.58.28.79.48.77.66.97.77.99.35.87.58.97.8

Deferred Policy Acquisition Cost Amortization Expense

us-gaap:DeferredPolicyAcquisitionCostAmortizationExpense

us-gaap:DeferredPolicyAcquisitionCostAmortizationExpense


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value150164164157149156154150148148147142141140138136137142140140139141137132135133132131133129128126126123120121117117116121122121125125126128
Percentage of DeferredPolicyAcquisitionCostAmortizationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating487.8509.4482.1489.6438.2453.8431.7415.1424.3434.0470.8372.9406.8447.4450.1439.8432.1457.1462.4461.6445.3476.6426.6430.1426.3424.8412.4402.6431.3429.3416.8411.2399.0396.9341.7364.9371.7373.0338.2340.6341.1347.1353.2347.3346.3359.4

Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value135132207146285-180.7052880101167-114.4487073-59.6999.487586830-51.2731642623124.51129-28.161371361021154-24.95990-39.16191-18.853101110-18.1187576-50.0971351581
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating437.4410.2608.1456.2835.5-523.979.7222.4290.0488.8-365.6184.2210.4-189.530.8188.0215.798.1-168.3104.1204.887.774.339.714.294.8-87.8114.0442.3337.436.5177.6-78.8291.9-110.9273.4-59.5323.9322.6-51.0210.0219.1-141.3377.442.1226.5

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxExpenseBenefit


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2625402757-41.501-3.223111831-32.5691113-17.092-10.29211173.619-25.1884.695152.7110.525-3.003-5.1283.694-7.2055.8244129-4.10815-15.69524-21.77925-13.5892831-14.3361818-26.4538-2.45920
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating84.778.8118.586.4167.6-120.3-9.031.852.491.5-104.130.737.6-54.2-33.438.053.711.6-82.715.549.29.11.6-9.7-16.211.7-22.517.9134.497.2-13.349.3-49.678.7-61.675.2-42.991.091.0-40.451.053.2-74.6108.3-6.756.0

Income Taxes Paid Net

us-gaap:IncomeTaxesPaidNet

us-gaap:IncomeTaxesPaidNet


Income
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-31
Value1517200.0-15.7421.2-0.0580.036-0.211-11.4750.703-0.006101.051
Percentage of IncomeTaxesPaidNet100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating44.654.058.80.0-44.13.3-0.20.1-0.7-30.12.0-0.035.33.4

Interest Expense

us-gaap:InterestExpense

us-gaap:InterestExpense


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value4.2354.3434.2624.2624.2684.2564.2564.2574.2664.2564.2214.2574.2564.34.2684.24.2292.51.0781.0120.960.950.8960.7850.7690.750.7370.7070.6880.5050.3960.3380.2120.3140.3670.3880.3780.410.8991.2861.6691.6951.7031.6331.8511.619
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating13.713.512.513.312.512.311.911.712.212.413.511.212.213.613.913.613.38.03.53.33.13.22.82.52.42.42.32.22.21.71.31.10.71.01.01.21.21.32.63.64.64.84.84.55.14.5

Interest Paid Net

us-gaap:InterestPaidNet

us-gaap:InterestPaidNet


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.0288.2750.0268.2750.0298.2690.0198.270.0298.2680.019
Percentage of InterestPaidNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating0.125.60.125.70.124.00.122.70.124.20.1

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value109106166118228-139.204316983135-81.8795860-42.60719465126-26.08226482323159.63926-20.9563194721539-9.26466-17.38266-5.2647379-3.7825758-23.647961761
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating352.7331.5489.6369.8667.9-403.588.8190.6237.6397.3-261.6153.5173.1-135.264.2150.0161.986.5-85.688.7155.678.572.749.430.483.0-65.496.1307.8240.249.9128.2-29.2213.2-49.2198.1-16.6233.0231.6-10.6159.0165.9-66.7269.148.8170.5

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value109106166118228-139.204316983135-81.8795860
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating352.7331.5489.6369.8667.9-403.588.8190.6237.6397.3-261.6153.5173.0
Percentage of InterestAndDividendIncomeOperating us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.0

Other Income

us-gaap:OtherIncome

us-gaap:OtherIncome


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2.1973.2041.4772.8941.3532.5621.8412.6032.352.32.1672.42.42.3252.275.42.1242.1051.8942.4061.8872.1232.0882.2812.2762.2662.0052.2752.092.3012.1992.6852.5212.3332.3842.5322.5442.7140.6633.5084.4433.273.0631.7612.181.293
Percentage of OtherIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating7.19.94.39.04.07.45.27.26.76.76.96.36.97.47.417.46.76.76.27.96.07.16.57.47.27.26.37.06.87.67.18.78.07.56.77.68.08.61.99.912.39.38.64.96.03.6

Policyholder Benefits And Claims Incurred Net

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet


Policyholder
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value657626629618495651738680656630724614605632654595588606589576595594564545521514533492483476516492486467546467497449472458451446514440439430
Percentage of PolicyholderBenefitsAndClaimsIncurredNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating2123.31940.41849.01924.91449.71889.22067.51872.91874.21843.32316.11609.21740.62006.52124.41921.01845.11944.41935.81897.51894.32000.31752.21766.11644.41632.71665.11512.51565.81576.01674.11596.31537.21498.21546.61400.61570.01428.91378.01290.71253.41272.11452.21224.11205.21200.0

us-gaap:PolicyholderBenefitsAndClaimsIncurredNet us-gaap:StatementBusinessSegments

mcy:PropertyandCasualtyLines


Policyholder
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value653622626614492648735677653626721610601628650591584601585570589588557538514506
Percentage of PolicyholderBenefitsAndClaimsIncurredNet99.499.599.599.499.499.599.699.599.599.499.699.499.399.499.499.399.399.299.299.099.099.098.998.798.698.5
Percentage of InterestAndDividendIncomeOperating2111.61929.71839.01913.21440.31879.12059.61863.01864.91832.72306.41599.11729.11994.02112.71907.51831.31928.81920.61879.41876.21979.81732.41743.21621.91608.6
Percentage of InterestAndDividendIncomeOperating mcy:PropertyandCasualtyLines0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AllOtherSegments


Policyholder
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value3.63.43.43.83.23.52.83.63.33.63.03.94.03.93.64.24.44.94.65.55.76.16.47.17.17.6
Percentage of PolicyholderBenefitsAndClaimsIncurredNet0.50.50.50.60.60.50.40.50.50.60.40.60.70.60.60.70.70.80.81.01.01.01.11.31.41.5
Percentage of InterestAndDividendIncomeOperating11.610.510.011.89.410.17.89.99.410.59.610.211.512.411.713.613.815.715.118.118.120.519.923.022.424.1
Percentage of InterestAndDividendIncomeOperating us-gaap:AllOtherSegments0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Premiums Earned Net

us-gaap:PremiumsEarnedNet

us-gaap:PremiumsEarnedNet


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value926915921899811922925915888870868858834808806801797789794790779767760745731720709705697683680678675662655646637635641643642638640642642640
Percentage of PremiumsEarnedNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating2994.32837.52706.82798.12376.32674.52592.02516.82537.02544.42773.92248.72397.52564.62619.52585.52500.52531.42608.42604.12480.72582.82360.72412.82307.92287.62212.12165.72262.22260.82208.42200.22133.62125.41856.31933.82012.02019.31869.71811.71783.81819.31807.01785.31762.11785.1

us-gaap:PremiumsEarnedNet us-gaap:ProductOrService

us-gaap:OtherInsuranceProductLine


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value423831373434312929282929292829292929303030293131
Percentage of PremiumsEarnedNet4.54.23.44.14.33.73.43.33.33.33.43.53.53.53.63.73.73.73.83.83.93.94.14.2
Percentage of InterestAndDividendIncomeOperating135.7120.292.5116.1101.398.688.882.083.483.994.278.183.490.195.595.293.194.699.899.496.5100.797.2101.6
Percentage of InterestAndDividendIncomeOperating us-gaap:OtherInsuranceProductLine0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PropertyAndCasualtyCommercialInsuranceProductLine


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value646261575155545351494948464444434241414139383837
Percentage of PremiumsEarnedNet7.06.86.76.46.36.05.95.85.85.75.75.75.65.65.55.45.35.25.25.25.15.05.05.0
Percentage of InterestAndDividendIncomeOperating208.7193.9180.6179.8149.6160.0151.8147.2146.7145.0159.1127.6134.2142.5144.8140.7132.9132.4136.2135.7127.0130.3118.3119.7
Percentage of InterestAndDividendIncomeOperating us-gaap:PropertyAndCasualtyCommercialInsuranceProductLine0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PropertyAndCasualtyPersonalInsuranceProductLine


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value650653664653579693701698684672670659645627623619617613615614607599592581
Percentage of PremiumsEarnedNet70.271.472.172.671.475.275.876.377.077.377.276.977.477.677.377.477.477.777.577.677.978.178.078.0
Percentage of InterestAndDividendIncomeOperating2102.52025.21952.02031.71696.72011.61964.71920.51953.41966.72140.61728.61855.91989.82024.42000.11935.01965.72021.02021.71932.62016.81840.51881.4
Percentage of InterestAndDividendIncomeOperating us-gaap:PropertyAndCasualtyPersonalInsuranceProductLine0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PropertyInsuranceProductLine


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value169160164151146139138133123119118120112107109108108105107105102999895
Percentage of PremiumsEarnedNet18.317.617.816.818.015.114.914.613.913.713.714.013.513.313.513.513.613.413.513.313.113.012.912.9
Percentage of InterestAndDividendIncomeOperating547.3498.2481.5470.4428.8404.4386.8367.2353.7348.8379.9314.5324.0342.1354.9349.5339.5338.8351.3347.4324.7335.0304.7310.1
Percentage of InterestAndDividendIncomeOperating us-gaap:PropertyInsuranceProductLine0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PremiumsEarnedNet us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:OtherInsuranceProductLine, mcy:PropertyandCasualtyLines


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value343124302726242222212222212021212120201919181918
Percentage of PremiumsEarnedNet3.73.52.63.33.42.92.62.52.52.52.62.62.52.52.62.62.62.62.62.52.52.42.52.5
Percentage of InterestAndDividendIncomeOperating112.198.271.493.380.577.768.662.463.463.271.258.260.965.468.567.865.865.768.365.562.462.659.660.8
Percentage of InterestAndDividendIncomeOperating us-gaap:OtherInsuranceProductLine mcy:PropertyandCasualtyLines0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherInsuranceProductLine, us-gaap:AllOtherSegments


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value7.37.17.27.37.17.27.27.17.07.17.27.67.87.88.38.58.79.09.61010111212
Percentage of PremiumsEarnedNet0.80.80.80.80.90.80.80.80.80.80.80.90.91.01.01.11.11.11.21.31.41.51.61.7
Percentage of InterestAndDividendIncomeOperating23.622.021.122.720.820.920.219.520.020.823.019.922.424.826.927.427.328.831.533.934.138.037.640.8
Percentage of InterestAndDividendIncomeOperating us-gaap:OtherInsuranceProductLine us-gaap:AllOtherSegments0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PropertyAndCasualtyCommercialInsuranceProductLine, mcy:PropertyandCasualtyLines


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value646261575155545351494948464444434241414139383837
Percentage of PremiumsEarnedNet7.06.86.76.46.36.05.95.85.85.75.75.75.65.65.55.45.35.25.25.25.15.05.05.0
Percentage of InterestAndDividendIncomeOperating208.7193.9180.6179.8149.6160.0151.8147.2146.7145.0159.1127.6134.2142.5144.8140.7132.9132.4136.2135.7127.0130.3118.3119.7
Percentage of InterestAndDividendIncomeOperating us-gaap:PropertyAndCasualtyCommercialInsuranceProductLine mcy:PropertyandCasualtyLines0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PropertyAndCasualtyPersonalInsuranceProductLine, mcy:PropertyandCasualtyLines


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value650653664653579693701698684672670659645627623619617613615614607599592581
Percentage of PremiumsEarnedNet70.271.472.172.671.475.275.876.377.077.377.276.977.477.677.377.477.477.777.577.677.978.178.078.0
Percentage of InterestAndDividendIncomeOperating2102.52025.21952.02031.71696.72011.61964.71920.51953.41966.72140.61728.61855.91989.82024.42000.11935.01965.72021.02021.71932.62016.81840.51881.4
Percentage of InterestAndDividendIncomeOperating us-gaap:PropertyAndCasualtyPersonalInsuranceProductLine mcy:PropertyandCasualtyLines0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PropertyInsuranceProductLine, mcy:PropertyandCasualtyLines


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value169160164151146139138133123119118120112107109108108105107105102999895
Percentage of PremiumsEarnedNet18.317.617.816.818.015.114.914.613.913.713.714.013.513.313.513.513.613.413.513.313.113.012.912.9
Percentage of InterestAndDividendIncomeOperating547.3498.2481.5470.4428.8404.4386.8367.2353.7348.8379.9314.5324.0342.1354.9349.5339.5338.8351.3347.4324.7335.0304.7310.1
Percentage of InterestAndDividendIncomeOperating us-gaap:PropertyInsuranceProductLine mcy:PropertyandCasualtyLines0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PremiumsEarnedNet us-gaap:StatementBusinessSegments

mcy:PropertyandCasualtyLines


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value919908914892804915918907881863861850826800798792789780784780768755748732718707
Percentage of PremiumsEarnedNet99.299.299.299.299.199.299.299.299.299.299.299.199.199.099.098.998.998.998.898.798.698.598.498.398.298.1
Percentage of InterestAndDividendIncomeOperating2970.72815.52685.42775.42355.62653.72571.92497.22517.12523.72750.82228.82375.12539.82592.52558.12473.32502.62576.82570.22446.72544.82323.12372.02266.82244.7
Percentage of InterestAndDividendIncomeOperating mcy:PropertyandCasualtyLines0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AllOtherSegments


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value7.37.17.27.37.17.27.27.17.07.17.27.67.87.88.38.58.79.09.610101112121313
Percentage of PremiumsEarnedNet0.80.80.80.80.90.80.80.80.80.80.80.90.91.01.01.11.11.11.21.31.41.51.61.71.81.9
Percentage of InterestAndDividendIncomeOperating23.622.021.122.720.820.920.219.520.020.823.019.922.424.826.927.427.328.831.533.934.138.037.640.841.342.8
Percentage of InterestAndDividendIncomeOperating us-gaap:AllOtherSegments0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Realized Investment Gains Losses

us-gaap:RealizedInvestmentGainsLosses

us-gaap:RealizedInvestmentGainsLosses


Realized
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value584111464158-251.32253353111-85.12-3.9114-58.73517202124-89.255-15.54525-8.2-26.286-39.348-9.961-21.6-20.0897646-4.26916-67.41544-12.27649-23.7595272-66.9192328-23.68186-27.71322
Percentage of RealizedInvestmentGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating190.0129.2335.3200.5463.7-728.670.291.7152.2324.8-271.9-10.241.1-186.456.266.966.378.5-293.0-51.0144.584.4-25.5-85.1-124.1-31.6-67.4-61.7247.0154.5-13.852.5-212.8141.3-34.7148.9-75.0167.3212.3-188.466.081.7-66.8240.2-76.061.4

Revenue From Contract With Customer Including Assessed Tax

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value5.06.34.34.54.54.73.84.24.24.23.74.04.04.33.63.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating16.219.512.614.013.213.610.611.612.012.311.810.511.513.611.712.6

Revenues

us-gaap:Revenues

us-gaap:Revenues


Revenues
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1018993107199810057089879879791017816894885783857858852847737808858823786752726744721719807762709728642740681731647722749615706705655766653699
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating3291.43076.63146.43107.62944.02053.42767.42715.62796.02975.92609.02345.02545.32485.52783.32770.02673.42716.42421.52661.02731.32774.12441.72435.22291.02363.22250.92211.02615.92522.82301.72361.42028.72374.21928.32190.32045.02295.22184.01733.21962.12010.31848.92130.31792.11950.2

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value66966554632861455916571658895873571656065433531352045132510150254938486347884801472246924628464645864618460046094562447643154340423142724189421041204136407040964246420842034232
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:ConsolidatedEntities

srt:ParentCompany


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-31
Value2431220120172163
Percentage of Assets38.437.437.142.4
Percentage of Assets38.437.437.142.4
Percentage of Assets srt:ParentCompany100.0100.0100.0100.0

Liabilities

us-gaap:Liabilities

us-gaap:Liabilities


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value45184449429542444099409340894070394838873816357834943448333932493175311830362985290028842807281727382748272426842638261424922500239723962347231722592238221222872400238724082461
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets67.567.967.969.169.371.669.469.369.169.370.267.467.167.265.564.764.364.163.462.261.461.560.760.659.759.559.258.257.858.457.857.656.756.156.055.054.854.154.455.856.556.757.358.2

us-gaap:Liabilities us-gaap:ConsolidatedEntities

srt:ParentCompany


Liabilitiesus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-31
Value398402400402
Percentage of Liabilities9.39.810.512.0
Percentage of Assets6.36.87.47.9
Percentage of Assets srt:ParentCompany16.418.319.818.6

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value66966554632861455916571658895873571656065433531352045132510150254938486347884801472246924628464645864618460046094562447643154340423142724189421041204136407040964246420842034232
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilitiesAndStockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Liabilities
Period End2020-12-312019-12-312018-12-312017-12-31
Value2431220120172163
Percentage of LiabilitiesAndStockholdersEquity38.437.437.142.4
Percentage of Assets38.437.437.142.4
Percentage of Assets srt:ParentCompany100.0100.0100.0100.0

Cash

us-gaap:Cash

us-gaap:Cash


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value3783383483222622522943152402703142612432902912842612362202292332352642952742342892792582382662501801851581881602042112093053341811742192421853548
Percentage of Cash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.75.25.55.24.44.45.05.44.24.85.84.94.75.75.75.75.34.94.64.84.95.05.76.46.05.16.36.15.75.36.25.84.34.33.84.53.94.95.25.17.27.94.30.00.00.04.40.00.0

us-gaap:Cash us-gaap:ConsolidatedEntities

srt:ParentCompany


Cashus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value2439248.4751120
Percentage of Cash7.113.57.72.95.37.6
Percentage of Assets0.40.70.40.20.20.4
Percentage of Assets srt:ParentCompany1.01.81.20.40.00.0

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value378338348322262252294315240270314291
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.75.25.55.24.44.45.05.44.24.85.85.7

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents us-gaap:ConsolidatedEntities

srt:ParentCompany


Cash
Period End2020-12-312019-12-312018-12-312017-12-31
Value2439248.475
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents7.113.57.72.9
Percentage of Assets0.40.70.40.2
Percentage of Assets srt:ParentCompany1.01.81.20.4

Short Term Investments

us-gaap:ShortTermInvestments

us-gaap:ShortTermInvestments


Short
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value375253335237494421362367253262270245302366280260375206181155185162153173372291229303315251165152294221179227236248138111143156
Percentage of ShortTermInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.94.15.74.28.47.26.36.64.74.95.24.85.97.35.75.47.84.33.83.34.03.53.33.88.16.35.06.87.35.83.93.67.05.34.45.55.86.13.32.73.43.7

us-gaap:ShortTermInvestments us-gaap:ConsolidatedEntities

srt:ParentCompany


Short
Period End2020-12-312019-12-312018-12-312017-12-31
Value4.269293.16621
Percentage of ShortTermInvestments1.15.91.27.0
Percentage of Assets0.10.50.10.4
Percentage of Assets srt:ParentCompany0.21.30.21.0

us-gaap:ShortTermInvestments us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring


Short
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value403520370238322189464384322347236300
Percentage of ShortTermInvestments0.00.098.794.196.079.693.991.189.194.693.499.3
Percentage of Assets6.07.95.93.95.43.37.96.55.66.24.45.9
Percentage of Assets us-gaap:FairValueInputsLevel1 us-gaap:FairValueMeasurementsRecurring0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring


Short
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value5.01274.92915134830373919162.02
Percentage of ShortTermInvestments0.00.01.35.94.020.46.18.910.95.46.60.7
Percentage of Assets0.10.40.10.20.20.80.50.60.70.40.30.0
Percentage of Assets us-gaap:FairValueInputsLevel2 us-gaap:FairValueMeasurementsRecurring0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ShortTermInvestments us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring, mcy:OtherShortTermInvestments


Short
Period End2021-06-302021-03-312020-12-31
Value0.010.0090.005
Percentage of ShortTermInvestments0.00.00.0
Percentage of Assets0.00.00.0
Percentage of Assets us-gaap:FairValueInputsLevel1 us-gaap:FairValueMeasurementsRecurring mcy:OtherShortTermInvestments0.00.00.0

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring, us-gaap:MoneyMarketFunds


Short
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value403520348238322188461381289314205270
Percentage of ShortTermInvestments0.00.092.894.196.079.493.390.680.085.780.989.4
Percentage of Assets6.07.95.53.95.43.37.86.55.15.63.85.3
Percentage of Assets us-gaap:FairValueInputsLevel1 us-gaap:FairValueMeasurementsRecurring us-gaap:MoneyMarketFunds0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring, us-gaap:ShortTermDebt


Short
Period End2020-12-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value210.00.5262.8222.32632323129
Percentage of ShortTermInvestments5.90.00.20.60.69.18.912.49.9
Percentage of Assets0.30.00.00.00.00.60.60.60.6
Percentage of Assets us-gaap:FairValueInputsLevel1 us-gaap:FairValueMeasurementsRecurring us-gaap:ShortTermDebt0.00.00.00.00.00.00.00.00.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:ShortTermDebt


Short
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value5.01274.92915134830373919162.02
Percentage of ShortTermInvestments0.00.01.35.94.020.46.18.910.95.46.60.7
Percentage of Assets0.10.40.10.20.20.80.50.60.70.40.30.0
Percentage of Assets us-gaap:FairValueInputsLevel2 us-gaap:FairValueMeasurementsRecurring us-gaap:ShortTermDebt0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ShortTermInvestments us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


Short
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value408548375253335237494421362367253302
Percentage of ShortTermInvestments0.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.18.45.94.15.74.28.47.26.36.64.75.9
Percentage of Assets us-gaap:FairValueMeasurementsRecurring0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ShortTermInvestments us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument

us-gaap:FairValueMeasurementsRecurring, mcy:OtherShortTermInvestments


Short
Period End2021-06-302021-03-312020-12-31
Value0.010.0090.005
Percentage of ShortTermInvestments0.00.00.0
Percentage of Assets0.00.00.0
Percentage of Assets us-gaap:FairValueMeasurementsRecurring mcy:OtherShortTermInvestments0.00.00.0

us-gaap:FairValueMeasurementsRecurring, us-gaap:MoneyMarketFunds


Short
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value403520348238322188461381289314205270
Percentage of ShortTermInvestments0.00.092.894.196.079.493.390.680.085.780.989.4
Percentage of Assets6.07.95.53.95.43.37.86.55.15.63.85.3
Percentage of Assets us-gaap:FairValueMeasurementsRecurring us-gaap:MoneyMarketFunds0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueMeasurementsRecurring, us-gaap:ShortTermDebt


Short
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value5.012726151348323972524832
Percentage of ShortTermInvestments0.00.07.25.94.020.66.79.420.014.319.110.6
Percentage of Assets0.10.40.40.20.20.90.60.71.30.90.90.6
Percentage of Assets us-gaap:FairValueMeasurementsRecurring us-gaap:ShortTermDebt0.00.00.00.00.00.00.00.00.00.00.00.0

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:PropertyPlantAndEquipmentGross


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value464481512485475456436419401396388
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.38.29.49.59.99.99.59.79.69.89.3

us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType

us-gaap:BuildingAndBuildingImprovements


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value139140138136
Percentage of PropertyPlantAndEquipmentGross30.029.227.028.2
Percentage of Assets2.22.42.52.7
Percentage of Assets us-gaap:BuildingAndBuildingImprovements0.00.00.00.0

us-gaap:FurnitureAndFixtures


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value4670123118
Percentage of PropertyPlantAndEquipmentGross10.014.624.024.4
Percentage of Assets0.71.22.32.3
Percentage of Assets us-gaap:FurnitureAndFixtures0.00.00.00.0

us-gaap:Land


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value18181818
Percentage of PropertyPlantAndEquipmentGross3.93.83.53.7
Percentage of Assets0.30.30.30.4
Percentage of Assets us-gaap:Land0.00.00.00.0

us-gaap:LeaseholdImprovements


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value7.0047.5479.9869.632
Percentage of PropertyPlantAndEquipmentGross1.51.61.92.0
Percentage of Assets0.10.10.20.2
Percentage of Assets us-gaap:LeaseholdImprovements0.00.00.00.0

us-gaap:SoftwareDevelopment


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value254244222202
Percentage of PropertyPlantAndEquipmentGross54.650.843.541.7
Percentage of Assets4.04.24.14.0
Percentage of Assets us-gaap:SoftwareDevelopment0.00.00.00.0

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value296292286280294318312372369364359354350345340335330324319314309299277262239219192
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.44.54.54.65.05.65.36.36.56.56.66.76.76.76.76.76.76.76.76.56.56.56.06.15.75.44.6

Amortization Of Intangible Assets

us-gaap:AmortizationOfIntangibleAssets

us-gaap:AmortizationOfIntangibleAssets


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value300000.0300000.0300000.0200000.0200000.0200000.01300000.01300000.01300000.01300000.01400000.01400000.01400000.01400000.01400000.01300000.01300000.01300000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01500000.01600000.01500000.01500000.01500000.01600000.01600000.01600000.0
Percentage of AmortizationOfIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:PropertyPlantAndEquipmentNet


Property
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value181178178174172169168168162155153149148145145144155155155155157158157157157156158160157155156154154158161165168172177179185190196201
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.72.72.82.82.93.02.92.92.82.82.82.82.82.82.82.93.13.23.33.23.33.43.43.43.43.43.53.53.53.53.63.63.73.73.93.94.14.24.44.44.44.54.74.8

Goodwill

us-gaap:Goodwill

us-gaap:Goodwill


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value4242424242424242424242424242424242424242424242424242424242424242424242424242424242424242
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.60.70.70.70.70.70.70.70.70.80.80.80.80.80.80.90.90.90.90.90.90.90.90.90.90.90.90.90.91.01.01.01.01.01.01.01.01.01.11.01.01.01.01.0

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill


Intangible
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1011119.93910101011131415161819202122242527283031323435353738404143444647495052535556586066
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.20.20.20.20.20.20.20.20.30.30.30.40.40.40.40.50.50.50.60.60.60.70.70.70.80.80.80.80.91.01.01.11.11.11.21.21.31.31.31.31.41.41.6

us-gaap:IntangibleAssetsNetExcludingGoodwill us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships


Intangible
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value2.012.1152.2220.6790.7430.8190.8942.0013.1084.2145.1516.257.3378.4359.2739.8881012131415161818192122
Percentage of IntangibleAssetsNetExcludingGoodwill18.619.119.66.87.37.98.416.823.629.233.237.040.243.044.745.847.749.551.152.954.455.857.157.458.559.562.7
Percentage of Assets0.00.00.00.00.00.00.00.00.10.10.10.10.10.20.20.20.20.20.30.30.30.40.40.40.40.50.5
Percentage of Assets us-gaap:CustomerRelationships0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TradeNames


Intangible
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value7.3797.547.77.868.0218.1818.3428.5028.6628.8238.9839.1449.3049.4659.6259.7859.94610101010101011111111
Percentage of IntangibleAssetsNetExcludingGoodwill68.468.268.079.178.978.778.471.465.861.157.854.151.048.246.445.343.341.640.138.436.935.634.434.033.032.132.4
Percentage of Assets0.10.10.10.10.10.10.10.10.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.3
Percentage of Assets us-gaap:TradeNames0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet

us-gaap:FiniteLivedIntangibleAssetsNet


Finite
Period End2021-06-302021-03-312020-12-312020-09-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value9.3899.6559.9228.53935373840414344464749505253555660
Percentage of FiniteLivedIntangibleAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.20.10.80.80.80.91.01.01.11.11.11.21.21.31.31.31.31.4

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OperatingLeaseRightOfUseAsset


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value363840414345444544410.0
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets0.60.60.60.70.70.80.80.80.80.70.0

Equity Securities Fv Ni

us-gaap:EquitySecuritiesFvNi

us-gaap:EquitySecuritiesFvNi


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value870810803809739619724657645616529688614537
Percentage of EquitySecuritiesFvNi100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets13.012.412.713.212.510.812.311.211.311.09.713.011.810.5

us-gaap:EquitySecuritiesFvNi us-gaap:ConsolidatedEntities

srt:ParentCompany


Equity
Period End2020-12-312019-12-31
Value110114
Percentage of EquitySecuritiesFvNi13.815.8
Percentage of Assets1.71.9
Percentage of Assets srt:ParentCompany4.55.2

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

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value733700691705645537586561543513430429
Percentage of EquitySecuritiesFvNi84.386.486.187.187.386.780.985.484.283.481.479.9
Percentage of Assets11.010.710.911.510.99.410.09.69.59.27.98.4
Percentage of Assets us-gaap:FairValueInputsLevel1 us-gaap:FairValueMeasurementsRecurring0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value543232312832493433333134
Percentage of EquitySecuritiesFvNi6.24.04.13.93.95.26.95.25.25.55.96.5
Percentage of Assets0.80.50.50.50.50.60.80.60.60.60.60.7
Percentage of Assets us-gaap:FairValueInputsLevel2 us-gaap:FairValueMeasurementsRecurring0.00.00.00.00.00.00.00.00.00.00.00.0

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

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


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value733700691705645537586561543513430429
Percentage of EquitySecuritiesFvNi84.386.486.187.187.386.780.985.484.283.481.479.9
Percentage of Assets11.010.710.911.510.99.410.09.69.59.27.98.4
Percentage of Assets us-gaap:FairValueInputsLevel1 us-gaap:FairValueMeasurementsRecurring us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:NonredeemablePreferredStock


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value543232312832493433333134
Percentage of EquitySecuritiesFvNi6.24.04.13.93.95.26.95.25.25.55.96.5
Percentage of Assets0.80.50.50.50.50.60.80.60.60.60.60.7
Percentage of Assets us-gaap:FairValueInputsLevel2 us-gaap:FairValueMeasurementsRecurring us-gaap:NonredeemablePreferredStock0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value870810803809739619724657645616529537
Percentage of EquitySecuritiesFvNi100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets13.012.412.713.212.510.812.311.211.311.09.710.5
Percentage of Assets us-gaap:FairValueMeasurementsRecurring0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:EquitySecuritiesFvNi us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument

us-gaap:FairValueMeasurementsRecurring, mcy:PrivateEquityFundsNetAssetValue


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value827879726550876066676571
Percentage of EquitySecuritiesFvNi9.59.69.99.08.88.112.19.210.311.012.413.3
Percentage of Assets1.21.21.31.21.10.91.51.01.21.21.21.4
Percentage of Assets us-gaap:FairValueMeasurementsRecurring mcy:PrivateEquityFundsNetAssetValue0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueMeasurementsRecurring, us-gaap:CommonStock


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value733700691705645537586561543513430429
Percentage of EquitySecuritiesFvNi84.386.486.187.187.386.780.985.484.283.481.479.9
Percentage of Assets11.010.710.911.510.99.410.09.69.59.27.98.4
Percentage of Assets us-gaap:FairValueMeasurementsRecurring us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueMeasurementsRecurring, us-gaap:NonredeemablePreferredStock


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value543232312832493433333134
Percentage of EquitySecuritiesFvNi6.24.04.13.93.95.26.95.25.25.55.96.5
Percentage of Assets0.80.50.50.50.50.60.80.60.60.60.60.7
Percentage of Assets us-gaap:FairValueMeasurementsRecurring us-gaap:NonredeemablePreferredStock0.00.00.00.00.00.00.00.00.00.00.00.0

Other Assets

us-gaap:OtherAssets

us-gaap:OtherAssets


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value3433383838334439352945282934322631202533273016271822212431291474172511142214118.661119.5121621
Percentage of OtherAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.50.50.60.60.60.60.80.70.60.50.80.50.60.70.60.50.60.40.50.70.60.60.40.60.40.50.50.50.70.70.31.70.40.60.30.30.50.40.30.20.30.20.40.5

us-gaap:OtherAssets us-gaap:ConsolidatedEntities

srt:ParentCompany


Other
Period End2020-12-312019-12-312018-12-312017-12-31
Value0.2210.3120.4460.663
Percentage of OtherAssets0.60.71.02.0
Percentage of Assets0.00.00.00.0
Percentage of Assets srt:ParentCompany0.00.00.00.0

Accrued Income Taxes Current

us-gaap:AccruedIncomeTaxesCurrent

us-gaap:AccruedIncomeTaxesCurrent


Accrued
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value34106.4016.8535.510.00.07.792244.96111262.3954.7260.00.00.05.2920.06715150.0
Percentage of AccruedIncomeTaxesCurrent100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.00.0
Percentage of Assets0.50.20.10.10.10.00.00.20.50.10.30.60.10.10.00.00.00.10.00.40.40.0

Long Term Debt

us-gaap:LongTermDebt

us-gaap:LongTermDebt


Long
Period End2020-12-312013-12-312012-12-31
Value375120120
Percentage of LongTermDebt100.0100.0100.0
Percentage of Assets5.92.82.9

Deferred Income Tax Liabilities Net

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:DeferredIncomeTaxLiabilitiesNet


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value524241199.1310.02721156.1660.07.1468.8077.2512213128.6469.962
Percentage of DeferredIncomeTaxLiabilitiesNet100.0100.0100.0100.0100.00.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.80.70.60.30.20.00.50.40.30.10.00.10.20.10.40.30.30.20.2

us-gaap:DeferredIncomeTaxLiabilitiesNet us-gaap:ConsolidatedEntities

srt:ParentCompany


Deferred
Period End2020-12-312019-12-312018-12-312017-12-31
Value8.477.0591.6918.242
Percentage of DeferredIncomeTaxLiabilitiesNet20.625.20.035.9
Percentage of Assets0.10.10.00.2
Percentage of Assets srt:ParentCompany0.30.30.10.4

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo


Lessee
Period End2020-12-31
Value12
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0
Percentage of Assets0.2

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree


Lessee
Period End2020-12-31
Value8095000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0
Percentage of Assets0.1

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour


Lessee
Period End2020-12-31
Value4388000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0
Percentage of Assets0.1

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive


Lessee
Period End2020-12-31
Value2832000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive


Lessee
Period End2020-12-31
Value2985000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0
Percentage of Assets0.0

Operating Lease Liability

us-gaap:OperatingLeaseLiability

us-gaap:OperatingLeaseLiability


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value394243444648474847430.0
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets0.60.60.70.70.80.80.80.80.80.80.0

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue


Lessee
Period End2020-12-31
Value46
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0
Percentage of Assets0.7

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount


Lessee
Period End2020-12-31
Value2584000.0
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount100.0
Percentage of Assets0.0

Stockholders Equity Including Portion Attributable To Noncontrolling Interest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-31
Value217821042032190018161623179918021767171916171734170916841761177617631745175218151822180718201829184718691875192419231861182218401833187518421893186018981857180918451820179417701494
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets32.532.132.130.930.728.430.630.730.930.729.832.632.932.834.535.335.735.936.637.838.638.539.339.440.340.540.841.842.241.642.242.443.343.944.045.045.245.945.644.243.543.342.741.80.0

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:ConsolidatedEntities

srt:ParentCompany


Stockholders
Period End2020-12-312019-12-312018-12-312017-12-31
Value2032179916171761
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0
Percentage of Assets32.130.629.834.5
Percentage of Assets srt:ParentCompany83.681.780.281.4

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:CumulativeEffectPeriodOfAdoption, us-gaap:StatementEquityComponents

srt:CumulativeEffectPeriodOfAdoptionAdjustedBalance, us-gaap:RetainedEarnings


Stockholders
Period End2021-03-312020-12-312020-03-312019-12-312018-12-312017-12-31
Value200519331524169815191663
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest95.395.193.994.493.994.5
Percentage of Assets30.630.626.728.828.032.6
Percentage of Assets srt:CumulativeEffectPeriodOfAdoptionAdjustedBalance us-gaap:RetainedEarnings0.00.00.00.00.00.0

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents

us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value98989898989898989898989797979795908881797674727169
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest4.54.74.95.25.46.15.55.55.65.76.15.65.75.85.55.55.04.74.54.34.14.14.14.80.0
Percentage of Assets1.51.51.61.61.71.71.71.71.71.81.81.81.91.91.92.02.01.91.91.91.91.81.70.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value2079200519331801171715241700170316691620151916361612158616631656172117821740176317801721169814231712
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest95.595.395.194.894.693.994.594.594.494.393.994.494.394.294.594.594.595.195.595.795.895.995.995.30.0
Percentage of Assets31.130.630.629.329.026.728.929.029.228.928.030.831.030.932.634.637.238.840.342.143.741.040.10.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value9898989898989898989898979797979796969594949390919090888381818181807979797977767575747472
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.51.51.61.61.71.71.71.71.71.81.81.81.91.91.91.92.02.02.02.02.02.02.02.02.02.01.91.81.81.81.91.91.91.91.91.91.91.91.91.81.81.81.81.7

us-gaap:CommonStockValue us-gaap:ConsolidatedEntities

srt:ParentCompany


Common
Period End2020-12-312019-12-312018-12-312017-12-31
Value98989897
Percentage of CommonStockValue100.0100.0100.0100.0
Percentage of Assets1.61.71.81.9
Percentage of Assets srt:ParentCompany4.14.54.94.5

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value20792005193318011717152417001703166916201519163616121586166316781666164916561717172417101721173117501775178218371840177917401758175317951763181417811820178017341770174617211698
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets31.130.630.629.329.026.728.929.029.228.928.030.831.030.932.633.433.733.934.635.836.536.437.237.338.238.438.839.940.339.840.340.541.442.042.143.143.244.043.742.341.741.541.040.1

us-gaap:RetainedEarningsAccumulatedDeficit us-gaap:ConsolidatedEntities

srt:ParentCompany


Retained
Period End2020-12-312019-12-312018-12-312017-12-31
Value1933170015191663
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0
Percentage of Assets30.628.928.032.6
Percentage of Assets srt:ParentCompany79.577.275.376.9

Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue us-gaap:StatementEquityComponents

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue

us-gaap:CommonStock


Adjustments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value35000.035000.036000.036000.035000.035000.035000.036000.036000.016000.041000.041000.040000.023000.0
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value14217416218316297106147901745814110578641011007477107564541756111477178494073385834631434-12.227775735-7.643471932
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating461.1540.7476.7571.5475.4281.6297.1407.0259.6510.8186.1369.8303.9248.7210.8328.3315.1237.9255.8355.2178.3153.8129.0244.4194.836.3146.7218.4255.9163.5130.0237.4120.8186.798.3191.446.4110.2-35.6218.7159.6101.4-21.6131.652.591.6

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-67.52-149.368-100.391-88.817-118.245-103.833-92.292-38.184-86.125-184.629-88.944-117.46-45.112-23.583-45.053-40.621-76.34-83.887-77.819-23.577-41.437-38.218-21.05311-34.093-7.203-37.909-25.528-123.3950.161-9.929-10.8852.302-31.451-2.766-26.527-9.00144-15.269-53.97714947-59.956-10.18356
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating-218.1-462.7-294.8-276.3-346.1-301.0-258.5-105.0-245.8-539.892.9-233.1-337.7-143.2-76.6-145.4-127.3-244.7-275.4-256.2-75.1-139.5-118.7-68.136.9-108.2-22.5-116.4-82.7-408.00.5-32.2-34.47.4-89.0-8.3-83.8-28.6128.7-43.0-149.9426.5132.6-166.6-27.9156.7

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-35.017-35.2-35.623-34.876-34.875-34.875-34.765-34.736-34.596-34.273-34.708-34.247-34.583-34.582-34.583-33.453-35.0618-3.574-33.471-34.257-33.354-34.282-34.063-33.213-32.69-29.609-11.991-33.77446-23.8016.4-32.086-33.641-33.272-33.496-32.385-32.374-30.305-157.719-32.738-32.373-32.768-32.096-32.025-32.109
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating-113.1-109.0-104.6-108.5-102.1-101.1-97.4-95.5-98.8-100.2-110.9-89.7-99.4-109.7-112.3-108.0-109.958.9-11.7-110.2-109.1-112.3-106.5-110.2-104.8-103.8-92.3-36.8-109.5153.0-77.220.7-101.3-107.9-94.2-100.3-102.2-102.8-88.3-444.0-90.9-92.2-92.4-89.2-87.8-89.5

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value14217416218316297106147901745814110578641011007477107564541756111477178494073385834631434-12.227775735-7.643471932
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating461.1540.7476.7571.5475.4281.6297.1407.0259.6510.8186.1369.8303.9248.7210.8328.3315.1237.9255.8355.2178.3153.8129.0244.4194.836.3146.7218.4255.9163.5130.0237.4120.8186.798.3191.446.4110.2-35.6218.7159.6101.4-21.6131.652.591.6

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value109106166118228-139.204316983135-81.8795860-42.60719465126-26.08226482323159.63926-20.9563194721539-9.26466-17.38266-5.2647379-3.7825758-23.647961761
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating352.7331.5489.6369.8667.9-403.588.8190.6237.6397.3-261.6153.5173.1-135.264.2150.0161.986.5-85.688.7155.678.572.749.430.483.0-65.496.1307.8240.249.9128.2-29.2213.2-49.2198.1-16.6233.0231.6-10.6159.0165.9-66.7269.148.8170.5

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value109106166118228-139.204316983135-81.8795860
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating352.7331.5489.6369.8667.9-403.588.8190.6237.6397.3-261.6153.5173.0
Percentage of InterestAndDividendIncomeOperating us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.0

Share Based Compensation

us-gaap:ShareBasedCompensation

us-gaap:ShareBasedCompensation


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value35000.035000.036000.036000.035000.035000.035000.036000.036000.016000.041000.040000.041000.023000.004000.021000.035000.03614000.0-31000.036000.0-3477000.02262000.0550000.01353000.01043000.01371000.01672000.0671000.0398000.0758000.0316000.0-129000.029000.0-682000.0397000.0-180000.095000.0293000.0292000.0198000.0116000.08000.0408000.0187000.0209000.0
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-67.52-149.368-100.391-88.817-118.245-103.833-92.292-38.184-86.125-184.629-88.944-117.46-45.112-23.583-45.053-40.621-76.34-83.887-77.819-23.577-41.437-38.218-21.05311-34.093-7.203-37.909-25.528-123.3950.161-9.929-10.8852.302-31.451-2.766-26.527-9.00144-15.269-53.97714947-59.956-10.18356
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating-218.1-462.7-294.8-276.3-346.1-301.0-258.5-105.0-245.8-539.892.9-233.1-337.7-143.2-76.6-145.4-127.3-244.7-275.4-256.2-75.1-139.5-118.7-68.136.9-108.2-22.5-116.4-82.7-408.00.5-32.2-34.47.4-89.0-8.3-83.8-28.6128.7-43.0-149.9426.5132.6-166.6-27.9156.7

Payments To Acquire Productive Assets

us-gaap:PaymentsToAcquireProductiveAssets

us-gaap:PaymentsToAcquireProductiveAssets


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value9.8737.929109.9759.484108.26410128.437.317.5016.9426.2065.1683.7187.1323.4254.1053.9394.3394.5963.7285.0865.375.9285.1578.6765.7596.4455.6884.6223.864.5012.9724.433.6234.1525.4663.0293.6285.9566.7436.8367.8767.431
Percentage of PaymentsToAcquireProductiveAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-35.017-35.2-35.623-34.876-34.875-34.875-34.765-34.736-34.596-34.273-34.708-34.247-34.583-34.582-34.583-33.453-35.0618-3.574-33.471-34.257-33.354-34.282-34.063-33.213-32.69-29.609-11.991-33.77446-23.8016.4-32.086-33.641-33.272-33.496-32.385-32.374-30.305-157.719-32.738-32.373-32.768-32.096-32.025-32.109
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of InterestAndDividendIncomeOperating-113.1-109.0-104.6-108.5-102.1-101.1-97.4-95.5-98.8-100.2-110.9-89.7-99.4-109.7-112.3-108.0-109.958.9-11.7-110.2-109.1-112.3-106.5-110.2-104.8-103.8-92.3-36.8-109.5153.0-77.220.7-101.3-107.9-94.2-100.3-102.2-102.8-88.3-444.0-90.9-92.2-92.4-89.2-87.8-89.5

Debt Instrument Interest Rate Stated Percentage

us-gaap:DebtInstrumentInterestRateStatedPercentage us-gaap:AssetsSoldUnderAgreementsToRepurchase, us-gaap:LongtermDebtType

us-gaap:DebtInstrumentInterestRateStatedPercentage

mcy:UnsecuredNotesOne, us-gaap:UnsecuredDebt


Debt
Period End2020-12-312019-12-312018-12-312017-03-08
Value4.40.0440.0440.044
Percentage of DebtInstrumentInterestRateStatedPercentage100.0100.0100.0100.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations mcy:UnsecuredNotesOne us-gaap:UnsecuredDebt0.00.00.00.0

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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value43.0143.0142.7744.7247.5248.1449.8549.1147.2246.0945.06
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

mcy:ExercisePriceRangeOne


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value43.0143.0135.4842.6442.4443.2943.67
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.083.095.389.389.987.6

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-312016-12-312016-09-302015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value41279.9622.7480.0141126136116105
Percentage of DeferredTaxLiabilities100.0100.0100.0100.00.0100.0100.0100.0100.0100.0

Unrecognized Tax Benefits

us-gaap:UnrecognizedTaxBenefits

us-gaap:UnrecognizedTaxBenefits


Unrecognized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value4.6346.051109.674121212105.9264.5673.8236.666
Percentage of UnrecognizedTaxBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:PaymentstoAcquireEquitySecuritiesFVNI

mcy:PaymentstoAcquireEquitySecuritiesFVNI


Paymentsto
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value239194229320319361321298297256248280248249205257
Percentage of PaymentstoAcquireEquitySecuritiesFVNI100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:PercentageOfUnadjustedFairValueObtained

mcy:PercentageOfUnadjustedFairValueObtained


Percentage
Period End2021-06-302021-03-312020-12-31
Value098.4-0.1
Percentage of PercentageOfUnadjustedFairValueObtained0.0100.0100.0

mcy:PremiumReceivableAllowanceforCreditLossWriteoff

mcy:PremiumReceivableAllowanceforCreditLossWriteoff


Premium
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value757000.01015000.01127000.0735000.0885000.0-1658000.01769000.01660000.0680000.0-1870000.0
Percentage of PremiumReceivableAllowanceforCreditLossWriteoff100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:ProceedsFromEquitySecuritiesCallsOfEquitySecuritiesAvailableForSale

mcy:ProceedsFromEquitySecuritiesCallsOfEquitySecuritiesAvailableForSale


Proceeds
Period End2020-09-30
Value880000.0
Percentage of ProceedsFromEquitySecuritiesCallsOfEquitySecuritiesAvailableForSale100.0

mcy:ProceedsfromSaleofEquitySecuritiesFVNI

mcy:ProceedsfromSaleofEquitySecuritiesFVNI


Proceedsfrom
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value225240324285295269282297280227313223196221199176
Percentage of ProceedsfromSaleofEquitySecuritiesFVNI100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:StockOptionsExercisedDecreaseForTaxWithholdingObligation us-gaap:StatementEquityComponents

mcy:StockOptionsExercisedDecreaseForTaxWithholdingObligation

us-gaap:CommonStock


Stock
Period End2021-06-302021-03-312020-06-302019-12-312019-09-302019-06-30
Value0-383000.0000-22000.0
Percentage of StockOptionsExercisedDecreaseForTaxWithholdingObligation0.0100.00.00.00.0100.0

us-gaap:AdvertisingExpense

us-gaap:AdvertisingExpense


Advertising
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value119.76.0109.2116.11210.0136.9118.8135.4126.0146.010.09.0154.9771012156.05.05.6196.3814.05.05.06.04.05.05.05.05.05.05.06.0
Percentage of AdvertisingExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssumedPremiumsEarned us-gaap:StatementBusinessSegments

us-gaap:AssumedPremiumsEarned

mcy:PropertyandCasualtyLines


Assumed
Period End2021-06-302021-03-312020-06-302020-03-31
Value3299000.03291000.02056000.02047000.0
Percentage of AssumedPremiumsEarned100.0100.0100.0100.0

us-gaap:AssumedPremiumsWritten us-gaap:StatementBusinessSegments

us-gaap:AssumedPremiumsWritten

mcy:PropertyandCasualtyLines


Assumed
Period End2021-06-302021-03-312020-06-302020-03-31
Value0.218120.2057.63
Percentage of AssumedPremiumsWritten100.0100.0100.0100.0

us-gaap:CapitalizedContractCostAmortization

us-gaap:CapitalizedContractCostAmortization


Capitalized
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value700000.0600000.0600000.0600000.0400000.0200000.0
Percentage of CapitalizedContractCostAmortization100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value40-10.04926599.317-41.562-20.97275-29.785-44.186
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CededPremiumsEarned

us-gaap:CededPremiumsEarned


Ceded
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value16161515121413131615149.01213
Percentage of CededPremiumsEarned100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CededPremiumsEarned us-gaap:StatementBusinessSegments

mcy:PropertyandCasualtyLines


Ceded
Period End2021-06-302021-03-312020-06-302020-03-31
Value-15.617-15.543-11.818-13.744
Percentage of CededPremiumsEarned-97.6-97.1-98.5-98.2

us-gaap:CededPremiumsWritten us-gaap:StatementBusinessSegments

us-gaap:CededPremiumsWritten

mcy:PropertyandCasualtyLines


Ceded
Period End2021-06-302021-03-312020-06-302020-03-31
Value-15.785-15.643-10.041-11.358
Percentage of CededPremiumsWritten100.0100.0100.0100.0

us-gaap:CommonStockDividendsPerShareDeclared

us-gaap:CommonStockDividendsPerShareDeclared


Common
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value0.63250.63250.630.630.630.62750.62750.62750.6250.6250.6250.62250.62250.6225620.00.620.620.61750.61750.61750.6150.6150.6150.61250.61250.61250.610.610.610.60.60.60.590.590.59
Percentage of CommonStockDividendsPerShareDeclared100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DepreciationAmortizationAndAccretionNet

us-gaap:DepreciationAmortizationAndAccretionNet


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1917171716161716161515151414131414136.6836.8446.5016.3576.5116.2176.6437.1077.9096.7516.6346.766.8726.7968.1028.8179.0719.2039.1849.5161010101011128.5198.562
Percentage of DepreciationAmortizationAndAccretionNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeGainLossOnDerivativeNet us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation

us-gaap:DerivativeGainLossOnDerivativeNet

us-gaap:EquityContract, us-gaap:Nondesignated, mcy:NetRealizedInvestmentGains


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.3230.464.5077.1448.9441.7121.4351.5592.4720.8732.6262.1412.8072.9220.4340.5571.0050.2960.5221.031.350.9440.8620.6951.0770.4470.7381.6270.5080.555
Percentage of DerivativeGainLossOnDerivativeNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeGainLossOnDerivativeNet us-gaap:HedgingDesignation

us-gaap:Nondesignated


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.3230.464.5077.1448.9441.7120.5691.1832.9872.639-1.8312.5342.4873.5240.8320.675-0.629-0.7234.145.2023.9312.107-4.866-3.7271.83.435-1.749-1.4632.2411.43
Percentage of DerivativeGainLossOnDerivativeNet100.0100.0100.0100.0100.0100.039.775.9120.8302.3-69.7118.488.6120.6191.7121.2-62.6-244.3793.1505.0291.2223.2-564.5-536.3167.1768.5-237.0-89.9441.1257.7

us-gaap:DirectPremiumsEarned us-gaap:StatementBusinessSegments

us-gaap:DirectPremiumsEarned

mcy:PropertyandCasualtyLines


Direct
Period End2021-06-302021-03-312020-06-302020-03-31
Value931921814927
Percentage of DirectPremiumsEarned100.0100.0100.0100.0

us-gaap:DirectPremiumsWritten

us-gaap:DirectPremiumsWritten


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-30
Value972953910957828957909997946922877917886869798835800814770817784800748785735
Percentage of DirectPremiumsWritten100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DirectPremiumsWritten us-gaap:ProductOrService

us-gaap:OtherInsuranceProductLine


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value524746433738383533312931323029303228292929282629
Percentage of DirectPremiumsWritten5.45.05.14.64.54.04.23.53.63.43.43.43.73.53.73.64.13.53.83.53.83.53.53.8

us-gaap:PropertyAndCasualtyCommercialInsuranceProductLine


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value666861625561515555544850494944454543404142403840
Percentage of DirectPremiumsWritten6.87.26.76.56.76.45.75.55.95.95.55.55.65.75.65.55.65.35.35.15.45.15.25.1

us-gaap:PropertyAndCasualtyPersonalInsuranceProductLine


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value646666636667555710673743697705668695666674607633600639595630595631582609
Percentage of DirectPremiumsWritten66.469.969.969.767.074.274.174.673.776.576.275.875.177.676.075.975.078.577.277.175.979.077.877.5

us-gaap:PropertyInsuranceProductLine


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value20717016718318014714516215913013014013811511712512210310511611699101106
Percentage of DirectPremiumsWritten21.417.918.319.221.815.416.016.316.814.214.915.315.613.314.715.115.312.713.714.214.812.413.513.6

us-gaap:DirectPremiumsWritten us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:OtherInsuranceProductLine, mcy:PropertyandCasualtyLines


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value434138353130302525242324252323222422222223201922
Percentage of DirectPremiumsWritten4.54.34.33.83.83.13.32.62.72.72.72.72.92.72.92.73.02.82.92.72.92.62.52.8

us-gaap:OtherInsuranceProductLine, us-gaap:AllOtherSegments


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value9.56.87.38.05.78.28.09.28.06.86.26.97.26.46.67.18.55.76.46.66.97.47.07.4
Percentage of DirectPremiumsWritten1.00.70.80.80.70.90.90.90.80.70.70.80.80.70.80.91.10.70.80.80.90.90.90.9

us-gaap:PropertyAndCasualtyCommercialInsuranceProductLine, mcy:PropertyandCasualtyLines


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value666861625561515555544850494944454543404142403840
Percentage of DirectPremiumsWritten6.87.26.76.56.76.45.75.55.95.95.55.55.65.75.65.55.65.35.35.15.45.15.25.1

us-gaap:PropertyAndCasualtyPersonalInsuranceProductLine, mcy:PropertyandCasualtyLines


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value646666636667555710673743697705668695666674607633600639595630595631582609
Percentage of DirectPremiumsWritten66.469.969.969.767.074.274.174.673.776.576.275.875.177.676.075.975.078.577.277.175.979.077.877.5

us-gaap:PropertyInsuranceProductLine, mcy:PropertyandCasualtyLines


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value20717016718318014714516215913013014013811511712512210310511611699101106
Percentage of DirectPremiumsWritten21.417.918.319.221.815.416.016.316.814.214.915.315.613.314.715.115.312.713.714.214.812.413.513.6

us-gaap:DirectPremiumsWritten us-gaap:StatementBusinessSegments

mcy:PropertyandCasualtyLines


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-30
Value963946903949823949901987938915871910879862792828792808764810777792741778727
Percentage of DirectPremiumsWritten99.099.399.299.299.399.199.199.199.299.399.399.299.299.399.299.198.999.399.299.299.199.199.199.198.9

us-gaap:AllOtherSegments


Direct
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-30
Value9.56.87.38.05.78.28.09.28.06.86.26.97.26.46.67.18.55.76.46.66.97.47.07.48.4
Percentage of DirectPremiumsWritten1.00.70.80.80.70.90.90.90.80.70.70.80.80.70.80.91.10.70.80.80.90.90.90.91.1

us-gaap:DividendsCommonStockCash us-gaap:StatementEquityComponents

us-gaap:DividendsCommonStockCash

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3535353434343434343434343434
Percentage of DividendsCommonStockCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 us-gaap:FinancialInstrument

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1

us-gaap:PrivateEquityFunds


Fair
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value00-1000.0-2000.0-7000.0111000.0-4000.00-31000.0-80000.0-254000.0-50000.0564000.0-19000.0-1440000.0-2049000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings10.00.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 us-gaap:FinancialInstrument

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3

us-gaap:PrivateEquityFunds


Fair
Period End2020-12-312020-09-302020-06-302020-03-312019-06-302019-03-31
Value000-1202000.000
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel30.00.00.0100.00.00.0

us-gaap:FairValueOptionChangesInFairValueGainLoss1

us-gaap:FairValueOptionChangesInFairValueGainLoss1


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value44268758166-240.99182450104-70.02-12.9078.793-58.53228172021-67.332-21.13237182.474-18.538-40.782-4.884-22.824-20.5284145-30.59321-78.72643-23.82944-24.7884954-64.3122020
Percentage of FairValueOptionChangesInFairValueGainLoss1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueOptionChangesInFairValueGainLoss1 us-gaap:InvestmentType

us-gaap:EquitySecurities


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value32346837111-186.373231.9281153-83.3949.2538.533-11.886237.765-5.081110-2.1438.6666.90711-16.938
Percentage of FairValueOptionChangesInFairValueGainLoss172.4130.278.464.167.177.3131.88.022.651.5119.1-71.797.020.382.944.1-25.152.8-15.310.123.337.3454.691.4

us-gaap:FinanceReceivables


Fair
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-30
Value-0.015-0.0130.039-0.0010.0330.0180.0470.031-0.002-0.008-0.041-0.1030.0
Percentage of FairValueOptionChangesInFairValueGainLoss1-0.0-0.00.1-0.0-0.00.10.10.00.0-0.10.1-0.60.0

us-gaap:FixedIncomeSecurities


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value12-8.057202150-50.013-6.1822384914-22.2570.224-46.2134.6989.7962510-77.497-19.5212811-8.695-1.602
Percentage of FairValueOptionChangesInFairValueGainLoss127.8-30.422.835.930.120.8-34.093.376.347.8-20.4172.42.579.016.755.6126.447.1115.192.477.862.4-351.58.6

us-gaap:Investments


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-30
Value44268758166-241.023182450104-70.063-12.9058.801-58.491172021-21.132
Percentage of FairValueOptionChangesInFairValueGainLoss1100.0100.0100.099.9100.0100.099.999.999.9100.0100.1100.0100.199.9100.6100.0100.0100.0

us-gaap:ShortTermInvestments


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value-0.0590.068-0.996-0.024.639-4.6370.397-0.3260.4910.734-0.9880.0990.044-0.3920.1270.15-0.2670.028-0.1270.532-0.410.061-0.0770.002
Percentage of FairValueOptionChangesInFairValueGainLoss1-0.10.3-1.1-0.02.81.92.2-1.41.00.71.4-0.80.50.70.50.9-1.30.10.2-2.5-1.10.3-3.1-0.0

us-gaap:FinanceLeasePrincipalPayments

us-gaap:FinanceLeasePrincipalPayments


Finance
Period End2021-06-302021-03-31
Value-5000.0393000.0
Percentage of FinanceLeasePrincipalPayments100.0100.0

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2.798-2.42313-9.899399.64-14.2718.2049.81822-25.0426.0820.78524-23.43810-0.5169.584-8.4143.994-1.038-5.128-17.577119.48-38.25815217.826-13.626-8.382174.01117-5.3560.210.3266.017-11.952-3.05410-5.411-35.1519.334115.119
Percentage of IncreaseDecreaseInAccountsPayableAndAccruedLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInBrokerDealerRelatedReceivablesPayablesNet

us-gaap:IncreaseDecreaseInBrokerDealerRelatedReceivablesPayablesNet


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value11-43.43611-14.14211-8.8646.307-1.32113-15.9019.612-1.3847.274-19.53722-7.2-9.5939-12.686-19.661.4060.982-5.271-0.12620-13.638-14.916-10.708150.678-45.6268-34.89910-3.239-2.0283.623-0.2754.01519-17.8593.264-6.575-4.05311-11.507
Percentage of IncreaseDecreaseInBrokerDealerRelatedReceivablesPayablesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value24-25.427-25.161-10.413-37.16341-12.519-10.359-18.329-31.33832-23.182-12.3641721-4.475-11.106-2.56824-4.623-15.239-2.632-0.53511176.1028.28924-30.165-10.6433.307-15.18732-24.09410-24.72635-21.683-23.22223-27.269-18.27729-26.28914-28.866
Percentage of IncreaseDecreaseInDeferredIncomeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredPolicyAcquisitionCosts

us-gaap:IncreaseDecreaseInDeferredPolicyAcquisitionCosts


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value7.086-3.257-4.4688.7228.0971.477-4.528107.4444.592-1.3487.2047.0664.058-3.7682.849-0.456-1.3-5.9312.7640.4281.803-3.4835.940.2041.899-4.2362.221-2.1016.852-1.8186.685-1.2454.934-0.4037.1983.7233.962-3.2033.0811.039-0.0664.7312.528-3.0471.075
Percentage of IncreaseDecreaseInDeferredPolicyAcquisitionCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve

us-gaap:IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value49494976-32.835-23.316671-3.688-41.82493018201384510264533352815178.055-4.597289.883
Percentage of IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value19131.64110-5.6968.276-7.93-38.585117.9615-2.534-6.7497.1030.183-1.4472617-3.74-0.825-12.68913-3.8780.951-7.2758.706-3.599-0.687-7.91310-5.636-2.801-11.369.48-2.669-1.417-7.1245.029-8.5464.279-11.19115.204-1.124-8.0378.188
Percentage of IncreaseDecreaseInOtherOperatingLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInPremiumsReceivable

us-gaap:IncreaseDecreaseInPremiumsReceivable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-0.30726-32.02118-20.58320-24.965371224-2.965301835-11.80816-9.26419-15.43414-5.6629-5.4428-3.45322-5.67911-8.13526-6.74316-12.24222-0.93287.52821-9.3851121-15.341-18.1261017-14.795
Percentage of IncreaseDecreaseInPremiumsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInReinsuranceRecoverable

us-gaap:IncreaseDecreaseInReinsuranceRecoverable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-1.6075.8247.114-8.675-20.169-8.397-24.674-23.12312-106.5881675.582-4.839-3.67345-1.129-0.727-0.692
Percentage of IncreaseDecreaseInReinsuranceRecoverable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInUnearnedPremiums

us-gaap:IncreaseDecreaseInUnearnedPremiums


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value3034-26.676425.23629-28.418684137-4.595504048-18.04626-1.20820-27.714221.56629-14.01360.98718-12.82119-0.0639-13.79329-10.26127-0.847381622-22.78118-5.87419-23.56712-11.59611
Percentage of IncreaseDecreaseInUnearnedPremiums100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestAndDividendIncomeOperating

us-gaap:InterestAndDividendIncomeOperating


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value30323432343435363534313834313030313130303129323031313232303030303131353331313435363535353635
Percentage of InterestAndDividendIncomeOperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value399242429373299264501448427274471432385254451414409275442415388261
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value205334150173209403142157212344135154194345117134168303100127170303
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1 us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent

us-gaap:Catastrophe


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.04.00.01.02.02.01.00.0-3.06.0
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears10.01.20.00.61.00.50.70.0-1.41.7

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value657626629618495651738680656630724614605632654595588606589576595594
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LossFromCatastrophes

us-gaap:LossFromCatastrophes


Loss
Period End2020-09-302019-09-30
Value293.0
Percentage of LossFromCatastrophes100.0100.0

us-gaap:OtherCostAndExpenseOperating

us-gaap:OtherCostAndExpenseOperating


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value70656671717663706867546360655064536557595761596064658358535453545458525051524853555863637057
Percentage of OtherCostAndExpenseOperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherUnderwritingExpense

us-gaap:OtherUnderwritingExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value222230230229220233217221217215201206202206189200191207198199197202197193199199
Percentage of OtherUnderwritingExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherUnderwritingExpense us-gaap:StatementBusinessSegments

mcy:PropertyandCasualtyLines


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value218227226225217229213217213212198202198202185196187203194194193197192188194193
Percentage of OtherUnderwritingExpense98.298.898.498.498.598.498.398.498.498.498.498.498.198.298.098.197.998.198.097.797.997.697.797.497.697.2

us-gaap:AllOtherSegments


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value3.92.83.73.73.43.73.73.53.53.43.23.33.83.83.73.94.04.03.94.54.24.94.55.14.85.6
Percentage of OtherUnderwritingExpense1.81.21.61.61.51.61.71.61.61.61.61.61.91.82.01.92.11.92.02.32.12.42.32.62.42.8

us-gaap:PaymentsForLossesAndLossAdjustmentExpense

us-gaap:PaymentsForLossesAndLossAdjustmentExpense


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value604576580546508668644606639618606587580600569549577579543542559565
Percentage of PaymentsForLossesAndLossAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsForProceedsFromOtherInvestingActivities


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-430000.0-543000.0-1499000.0-6523000.0-7765000.0-4790000.0-1275000.0-1392000.0-2159000.0-1421000.0-2041000.0-1937000.0-3083000.0-3044000.0-1934000.03000.0556000.0-559000.0-419000.0-843000.0-1396000.0-947000.0-182000.0-910000.0-239000.0-1142000.0-576000.0-1339000.0-717000.0-840000.0-194000.0-134000.0-686000.0-727000.0-351000.0-294000.0-606000.0-1004000.0-2877000.0-2713000.0-2403000.0-4033000.0-3286000.0-417000.0-3638000.0473000.0
Percentage of PaymentsForProceedsFromOtherInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromShortTermInvestments

us-gaap:PaymentsForProceedsFromShortTermInvestments


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312015-12-31
Value-144.033145121-81.56195-254.8117260-4.917113-6.097-7.86125-57.11-61.836-115.29416722
Percentage of PaymentsForProceedsFromShortTermInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsOfOrdinaryDividends

us-gaap:PaymentsOfOrdinaryDividends


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value3535163434349.80434
Percentage of PaymentsOfOrdinaryDividends100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value34423019123611533410690147146158153179213206871622783342511043861582871443741496115317720619422120920412513112911481126577716676112
Percentage of PaymentsToAcquireAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PremiumReceivableCreditLossExpenseReversal

us-gaap:PremiumReceivableCreditLossExpenseReversal


Premium
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value390000.02141000.0-846000.0-559000.0-719000.0-8169000.0-1741000.0-1506000.0-331000.0
Percentage of PremiumReceivableCreditLossExpenseReversal100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PremiumsReceivableAllowanceForDoubtfulAccountsRecoveries

us-gaap:PremiumsReceivableAllowanceForDoubtfulAccountsRecoveries


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value147000.0156000.0281000.0176000.0166000.0189000.0160000.0268000.0227000.0170000.0
Percentage of PremiumsReceivableAllowanceForDoubtfulAccountsRecoveries100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PremiumsWrittenNet us-gaap:StatementBusinessSegments

us-gaap:PremiumsWrittenNet

mcy:PropertyandCasualtyLines


Premiums
Period End2021-06-302021-03-312020-06-302020-03-31
Value947943813946
Percentage of PremiumsWrittenNet100.0100.0100.0100.0

us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities

us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value122103966942415811958809088926213917799159225133108180103142538711696575911168828120013811673124143688253817773
Percentage of ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value444140208323801.9133815402958601321422216558221494914153163349527355551079.568612220352145539658711558
Percentage of ProceedsFromSaleOfAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromStockOptionsExercised

us-gaap:ProceedsFromStockOptionsExercised


Proceeds
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0215000.000110000.00138000.0453000.018000.0340000.0000991000.001171000.0926000.0706000.00000828000.01283000.04447000.01682000.034000.084000.064000.058000.01324000.00394000.001026000.01072000.01141000.0169000.0143000.0498000.042000.0216000.0286000.0189000.0
Percentage of ProceedsFromStockOptionsExercised0.0100.00.00.0100.00.0100.0100.0100.0100.00.00.00.0100.00.0100.0100.0100.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded

us-gaap:ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded


Reinsurance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4.01.05.07.0151.0-20.01.0-6.0-58.0244142.01.0
Percentage of ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReinsuranceRecoverableCreditLossExpenseReversal

us-gaap:ReinsuranceRecoverableCreditLossExpenseReversal


Reinsurance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-06-30
Value0-91000.033000.0-30000.0-60000.0-11000.00
Percentage of ReinsuranceRecoverableCreditLossExpenseReversal0.0100.0100.0100.0100.0100.00.0

us-gaap:ReinsuranceRetentionPolicyAmountRetained

us-gaap:ReinsuranceRetentionPolicyAmountRetained


Reinsurance
Period End2021-06-302021-03-312020-12-31
Value0.0400.0
Percentage of ReinsuranceRetentionPolicyAmountRetained0.0100.00.0

us-gaap:ReinsuranceRetentionPolicyReinsuredRiskPercentage

us-gaap:ReinsuranceRetentionPolicyReinsuredRiskPercentage


Reinsurance
Period End2021-06-302021-03-31
Value071.0
Percentage of ReinsuranceRetentionPolicyReinsuredRiskPercentage0.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate


Share
Period End2021-06-302021-03-31
Value05.4
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate0.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate


Share
Period End2021-06-302021-03-31
Value033.18
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate0.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate


Share
Period End2021-06-302021-03-31
Value02.62
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate0.0100.0

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised

us-gaap:CommonStock


Stock
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0215000.000110000.00138000.0453000.018000.0340000.000
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised0.0100.00.00.0100.00.0100.0100.0100.0100.00.00.0

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense


Supplemental
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value671627632620482636738681647629702607584589618591578602573569572554
Percentage of SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense

us-gaap:SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense


Supplemental
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-14.202-1.207-2.532-1.9571215-0.529-0.4359.3961.362226.482142364.1104.1167.12239
Percentage of SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UnderwritingIncomeLoss

us-gaap:UnderwritingIncomeLoss


Underwriting
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value475961519537-29.9121523-58.63726-30.5-36.65.317-24.76.715-13.4-29.8-1.26.1106.8
Percentage of UnderwritingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UnderwritingIncomeLoss us-gaap:StatementBusinessSegments

mcy:PropertyandCasualtyLines


Underwriting
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value475861519537-30.6121523-59.63726-30.6-37.64.917-24.85.615-14.2-30.1-2.45.79.56.5
Percentage of UnderwritingIncomeLoss100.498.599.8100.499.5100.0102.3100.098.799.6101.798.9100.0100.3102.792.598.3100.483.698.0106.0101.0200.093.488.895.6

us-gaap:AllOtherSegments


Underwriting
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-0.20.90.1-0.20.50.00.70.00.20.11.00.40.00.11.00.40.30.11.10.30.80.31.20.41.20.3
Percentage of UnderwritingIncomeLoss-0.41.50.2-0.40.50.0-2.30.01.30.4-1.71.10.0-0.3-2.77.51.7-0.416.42.0-6.0-1.0-100.06.611.24.4

us-gaap:UnrecognizedTaxBenefitsPeriodIncreaseDecrease

us-gaap:UnrecognizedTaxBenefitsPeriodIncreaseDecrease


Unrecognized
Period End2020-12-31
Value-2817000.0
Percentage of UnrecognizedTaxBenefitsPeriodIncreaseDecrease100.0

dei:EntityCommonStockSharesOutstanding

dei:EntityCommonStockSharesOutstanding


Entity
Period End2020-07-29
Value55
Percentage of EntityCommonStockSharesOutstanding100.0

mcy:AmortizedCostOnFixedMaturityTradingInvestments

mcy:AmortizedCostOnFixedMaturityTradingInvestments


Amortized
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value35953434338833443207322929733013305330112969295129252905282327762897288427952876282328552804280228042772252325092597255925232481241323862270231823562364234523812496249426172673
Percentage of AmortizedCostOnFixedMaturityTradingInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:CostEquitySecurityTradingInvestments

mcy:CostEquitySecurityTradingInvestments


Cost
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value694667695769737729648604594577544619554498474479395388331359349326313307307362223444379312223267492484475458459385388368381341336308
Percentage of CostEquitySecurityTradingInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:CostEquitySecurityTradingInvestments us-gaap:ConsolidatedEntities

srt:ParentCompany


Cost
Period End2020-12-312019-12-312018-12-312017-12-31
Value7581110113
Percentage of CostEquitySecurityTradingInvestments10.812.620.323.9

mcy:CostShortTermInvestments

mcy:CostShortTermInvestments


Cost
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value409548376253335242494421362367254263270245302366280260375206181155185162153174315291229303315251165152294221179227236251139111143156
Percentage of CostShortTermInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:CostShortTermInvestments us-gaap:ConsolidatedEntities

srt:ParentCompany


Cost
Period End2020-12-312019-12-312018-12-312017-12-31
Value4.269293.16621
Percentage of CostShortTermInvestments1.15.91.27.0

mcy:DeferredTaxLiabilitiesAcquisitionCosts

mcy:DeferredTaxLiabilitiesAcquisitionCosts


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value5148454170706968656059
Percentage of DeferredTaxLiabilitiesAcquisitionCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:DeferredTaxLiabilitiesTaxAmortizationInExcessOfBookAmortization

mcy:DeferredTaxLiabilitiesTaxAmortizationInExcessOfBookAmortization


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value4666000.03264000.02729000.02280000.03030000.02514000.01982000.01447000.0914000.0442000.024000.0
Percentage of DeferredTaxLiabilitiesTaxAmortizationInExcessOfBookAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:DeferredTaxLiabilitiesUndistributedInsuranceSubsidiaries

mcy:DeferredTaxLiabilitiesUndistributedInsuranceSubsidiaries


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value3382000.02855000.03017000.03907000.03985000.04022000.04486000.04024000.04499000.03962000.04447000.0
Percentage of DeferredTaxLiabilitiesUndistributedInsuranceSubsidiaries100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:IncomeTaxPayableDueToAffiliate us-gaap:ConsolidatedEntities

mcy:IncomeTaxPayableDueToAffiliate

srt:ParentCompany


Income
Period End2020-12-312019-12-312018-12-312017-12-31
Value2.7244.1060.5817
Percentage of IncomeTaxPayableDueToAffiliate100.0100.0100.0100.0

mcy:IncomeTaxReceivableDueFromAffiliate us-gaap:ConsolidatedEntities

mcy:IncomeTaxReceivableDueFromAffiliate

srt:ParentCompany


Income
Period End2020-12-312019-12-312018-12-312017-12-31
Value5.8629.192196.338
Percentage of IncomeTaxReceivableDueFromAffiliate100.0100.0100.0100.0

mcy:LesseeOperatingLeaseNotYetCommencedAmount

mcy:LesseeOperatingLeaseNotYetCommencedAmount


Lessee
Period End2020-12-31
Value5000000.0
Percentage of LesseeOperatingLeaseNotYetCommencedAmount100.0

mcy:LiabilityforCatastropheClaimsNetofReinsuranceBenefits us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent

mcy:LiabilityforCatastropheClaimsNetofReinsuranceBenefits

us-gaap:Catastrophe


Liabilityfor
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312019-03-312018-12-312017-12-31
Value603564142.0535.06779
Percentage of LiabilityforCatastropheClaimsNetofReinsuranceBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:NotesPayablePrincipal

mcy:NotesPayablePrincipal


Notes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value375375375375375375375375375375375375375375375375375375320
Percentage of NotesPayablePrincipal100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:ReinsuranceRecoverablesNet

mcy:ReinsuranceRecoverablesNet


Reinsurance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value52544841507078
Percentage of ReinsuranceRecoverablesNet100.0100.0100.0100.0100.0100.0100.0

mcy:ReissuanceRecoverable

mcy:ReissuanceRecoverable


Reissuance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value525454544969761031071271805046526410111213131414141413127.9216.8057.7485.729
Percentage of ReissuanceRecoverable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:ReissuanceRecoverable us-gaap:CumulativeEffectPeriodOfAdoption

srt:CumulativeEffectPeriodOfAdoptionAdjustedBalance


Reissuance
Period End2020-12-312019-12-312018-12-312017-12-31
Value547518064
Percentage of ReissuanceRecoverable100.099.8100.0100.0

mcy:SecurityDepositsByInsuranceCompanies

mcy:SecurityDepositsByInsuranceCompanies


Security
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value1516151719211817161814
Percentage of SecurityDepositsByInsuranceCompanies100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mcy:TradingSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue

mcy:TradingSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue


Trading
Period End2020-12-31
Value540
Percentage of TradingSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue100.0

mcy:TradingSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue

mcy:TradingSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue


Trading
Period End2020-12-31
Value693
Percentage of TradingSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue100.0

mcy:TradingSecuritiesDebtMaturitiesAfterTenYearsFairValue

mcy:TradingSecuritiesDebtMaturitiesAfterTenYearsFairValue


Trading
Period End2020-12-31
Value2069
Percentage of TradingSecuritiesDebtMaturitiesAfterTenYearsFairValue100.0

mcy:TradingSecuritiesDebtMaturitiesWithinOneYearFairValue

mcy:TradingSecuritiesDebtMaturitiesWithinOneYearFairValue


Trading
Period End2020-12-31
Value246
Percentage of TradingSecuritiesDebtMaturitiesWithinOneYearFairValue100.0

mcy:TwoPrivateEquityFundsUsingNAV

mcy:TwoPrivateEquityFundsUsingNAV


Two
Period End2021-06-302021-03-312020-12-312020-09-30
Value81767871
Percentage of TwoPrivateEquityFundsUsingNAV100.0100.0100.0100.0

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value19519119418019015014315614713711513813313210813012112411211911511612213912811813014112011212713311611396100100999410510898106114
Percentage of AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccountsReceivableGross

us-gaap:AccountsReceivableGross


Accounts
Period End2020-12-312019-12-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1200000.01200000.01200000.01100000.01100000.01100000.01200000.0
Percentage of AccountsReceivableGross100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccruedInvestmentIncomeReceivable

us-gaap:AccruedInvestmentIncomeReceivable


Accrued
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value4044424342434041424345484542394244414141424042414340383839363635333331333233323335353637
Percentage of AccruedInvestmentIncomeReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccruedInvestmentIncomeReceivable us-gaap:ConsolidatedEntities

srt:ParentCompany


Accrued
Period End2020-12-312019-12-312018-12-312017-12-31
Value0.020.090.1610.178
Percentage of AccruedInvestmentIncomeReceivable0.00.20.40.5

us-gaap:AlternativeInvestment us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:AlternativeInvestment

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value5698000.05712000.05725000.05736000.05697000.05698000.05665000.05653000.05635000.05588000.05557000.05565000.0
Percentage of AlternativeInvestment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AlternativeInvestment us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value5698000.05712000.05725000.05736000.05697000.05698000.05665000.05653000.05635000.05588000.05557000.05565000.0
Percentage of AlternativeInvestment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:AssetsFairValueDisclosure

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value1151123410769689917501073968890885692836768743
Percentage of AssetsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value38123639357935133351336231563193321231123013300129982921
Percentage of AssetsFairValueDisclosure331.1294.7332.6362.8338.0448.1294.1329.7360.9351.7435.2358.8390.1393.1

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value50464951473445544407416243174223417040663773390938393738
Percentage of AssetsFairValueDisclosure438.3401.1439.9470.3444.6554.7402.4436.1468.5459.4544.9467.3499.5502.9

us-gaap:CapitalizedContractCostAccumulatedAmortization

us-gaap:CapitalizedContractCostAccumulatedAmortization


Capitalized
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value3400000.02700000.02100000.01500000.01000000.0500000.0300000.0
Percentage of CapitalizedContractCostAccumulatedAmortization100.0100.0100.0100.0100.0100.0100.0

us-gaap:CapitalizedContractCostNet

us-gaap:CapitalizedContractCostNet


Capitalized
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value5200000.05000000.04800000.05200000.05700000.05500000.04400000.0
Percentage of CapitalizedContractCostNet100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerRefundLiability

us-gaap:ContractWithCustomerRefundLiability


Contract
Period End2020-12-312019-12-312018-12-312018-09-302018-06-302017-12-31
Value900000.0700000.0700000.0700000.0700000.0700000.0
Percentage of ContractWithCustomerRefundLiability100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrumentFaceAmount us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType

us-gaap:DebtInstrumentFaceAmount

us-gaap:FairValueInputsLevel2, us-gaap:Borrowings, us-gaap:UnsecuredDebt


Debt
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-31
Value375375375375375375375375375375375375375375180
Percentage of DebtInstrumentFaceAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet

us-gaap:DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2268000.02368000.02468000.02568000.02667000.02767000.02867000.02966000.03066000.03166000.03266000.03365000.03465000.03565000.03665000.03764000.03864000.03956000.00
Percentage of DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredIncomeTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value13811060861090.01190.00.00.05.3335.306122.3180.00.00.0120.445171.0029.9150.0
Percentage of DeferredIncomeTaxLiabilities100.0100.0100.0100.0100.00.0100.00.00.00.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.00.0

us-gaap:DeferredPolicyAcquisitionCosts

us-gaap:DeferredPolicyAcquisitionCosts


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value250243246251242234233237227219215216209202198201199199200206203203201205199199197201199201194196189190185186179175171174171170170175
Percentage of DeferredPolicyAcquisitionCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredPolicyAcquisitionCostsAndValueOfBusinessAcquired

us-gaap:DeferredPolicyAcquisitionCostsAndValueOfBusinessAcquired


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value246233215198200201197194185171170175200
Percentage of DeferredPolicyAcquisitionCostsAndValueOfBusinessAcquired100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsGross


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value97827363154142135141136123131
Percentage of DeferredTaxAssetsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsOther

us-gaap:DeferredTaxAssetsOther


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value6401000.03348000.03257000.03174000.08828000.09596000.07448000.05653000.04860000.03568000.04337000.0
Percentage of DeferredTaxAssetsOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value293000.0314000.0356000.0387000.0726000.0857000.0942000.01714000.01723000.04638000.05389000.0
Percentage of DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value15129.2456.4519.8649.5181112151515
Percentage of DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value148.0997.0196.19211111312101114
Percentage of DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value6158524777757168666160
Percentage of DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesOther

us-gaap:DeferredTaxLiabilitiesOther


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value9335000.06481000.04719000.05417000.06211000.08769000.09087000.09184000.07711000.05003000.05475000.0
Percentage of DeferredTaxLiabilitiesOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value128.1054.5945.68610109.4149.667101516
Percentage of DeferredTaxLiabilitiesPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities

us-gaap:DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value56410.02715234733483118
Percentage of DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeAsset us-gaap:FinancialInstrument

us-gaap:DerivativeFairValueOfDerivativeAsset

us-gaap:Investments


Derivative
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value47294312376837323547
Percentage of DerivativeFairValueOfDerivativeAsset100.0100.0100.0100.0100.0

us-gaap:NotesReceivable


Derivative
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value5.7255.6655.5575.5650.0
Percentage of DerivativeFairValueOfDerivativeAsset0.10.10.10.10.0

us-gaap:DerivativeFairValueOfDerivativeLiability us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation

us-gaap:DerivativeFairValueOfDerivativeLiability

us-gaap:OtherLiabilities, us-gaap:EquityContract, us-gaap:Nondesignated


Derivative
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302011-12-31
Value0.1670.0811.3561.9773.1540.0770.2370.4050.7160.0030.5890.780.5050.1230.1460.1040.2850.020.1220.3090.2620.260.266-0.0510.8880.1940.3480.6350.4260.140.00.3310.6280.175-0.1710.6430.655
Percentage of DerivativeFairValueOfDerivativeLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeLiability us-gaap:HedgingDesignation

us-gaap:Nondesignated


Derivative
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value0.1670.0811.3561.9773.1540.0771.4042.1273.0284.8541.552.1731.3061.3231.7351.8290.7853.4077.90910116.325-1.6152.34.2191.6350.6350.4260.140.00.3310.6280.278-0.4311.0420.9511.3251.1443.0894.679
Percentage of DerivativeFairValueOfDerivativeLiability100.0100.0100.0100.0100.0100.0592.4525.2422.9161800.0263.2278.6258.61075.61188.41758.73925.02792.62559.53839.34532.72377.83166.7259.02174.7469.8100.0100.0100.00.0100.0100.0158.9252.0162.10.0202.30.00.00.0

us-gaap:DerivativeLiabilities us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument

us-gaap:DerivativeLiabilities

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring, us-gaap:EquityContract


Derivative
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value167000.081000.01356000.01977000.03154000.077000.0237000.0405000.0716000.03000.0123000.0
Percentage of DerivativeLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeLiabilities us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument

us-gaap:FairValueMeasurementsRecurring, us-gaap:EquityContract


Derivative
Period End2021-06-302021-03-31
Value167000.081000.0
Percentage of DerivativeLiabilities100.0100.0

us-gaap:DerivativeLiabilities us-gaap:FinancialInstrument

us-gaap:EquityContract


Derivative
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1356000.01977000.03154000.077000.0237000.0405000.0716000.03000.0123000.0
Percentage of DerivativeLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DueFromAffiliates us-gaap:ConsolidatedEntities

us-gaap:DueFromAffiliates

srt:ParentCompany


Due
Period End2020-12-312019-12-312018-12-312017-12-31
Value250000.0244000.01172000.0231000.0
Percentage of DueFromAffiliates100.0100.0100.0100.0

us-gaap:DueToAffiliateCurrentAndNoncurrent us-gaap:ConsolidatedEntities

us-gaap:DueToAffiliateCurrentAndNoncurrent

srt:ParentCompany


Due
Period End2020-12-312019-12-312018-12-312017-12-31
Value30000.022000.03082000.0507000.0
Percentage of DueToAffiliateCurrentAndNoncurrent100.0100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions


Employee
Period End2021-06-302021-03-312020-09-30
Value100000.0100000.0200000.0
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions us-gaap:PlanName

mcy:TwoThousandFifteenPlan


Employee
Period End2020-12-31
Value200000.0
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions0.0

us-gaap:FinanceLeaseLiability

us-gaap:FinanceLeaseLiability


Finance
Period End2020-12-31
Value2836000.0
Percentage of FinanceLeaseLiability100.0

us-gaap:FinanceLeaseLiabilityPaymentsDue

us-gaap:FinanceLeaseLiabilityPaymentsDue


Finance
Period End2020-12-31
Value2886000.0
Percentage of FinanceLeaseLiabilityPaymentsDue100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths


Finance
Period End2020-12-31
Value622000.0
Percentage of FinanceLeaseLiabilityPaymentsDueNextTwelveMonths100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFive

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFive


Finance
Period End2020-12-31
Value398000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearFive100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour


Finance
Period End2020-12-31
Value622000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearFour100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree


Finance
Period End2020-12-31
Value622000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearThree100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo


Finance
Period End2020-12-31
Value622000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearTwo100.0

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount


Finance
Period End2020-12-31
Value50000.0
Percentage of FinanceLeaseLiabilityUndiscountedExcessAmount100.0

us-gaap:FinanceLeaseRightOfUseAsset

us-gaap:FinanceLeaseRightOfUseAsset


Finance
Period End2020-12-31
Value3107000.0
Percentage of FinanceLeaseRightOfUseAsset100.0

us-gaap:FinancialLiabilitiesFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FinancialLiabilitiesFairValueDisclosure

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring


Financial
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value0.1670.0811.3561.9773.1540.0770.2370.4050.7160.0030.5890.780.123
Percentage of FinancialLiabilitiesFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialLiabilitiesFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:Borrowings, us-gaap:UnsecuredDebt


Financial
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value406409406394394384372362361364385
Percentage of FinancialLiabilitiesFairValueDisclosure29951.620690.412883.6512050.6166299.294913.852044.412089133.361310.446761.0313482.1

us-gaap:FinancialLiabilitiesFairValueDisclosure us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


Financial
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value0.1670.0811.3561.9773.1540.0771.4042.1273.0284.8541.552.1731.323
Percentage of FinancialLiabilitiesFairValueDisclosure100.0100.0100.0100.0100.0100.0592.4525.2422.9161800.0263.2278.61075.6

us-gaap:FinancialLiabilitiesFairValueDisclosure us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType

us-gaap:FairValueMeasurementsRecurring, us-gaap:Borrowings, us-gaap:UnsecuredDebt


Financial
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value406409406394394384372362361364385
Percentage of FinancialLiabilitiesFairValueDisclosure29951.620690.412883.6512050.6166299.294913.852044.412089133.361310.446761.0313482.1

us-gaap:FinancialLiabilitiesFairValueDisclosure us-gaap:FairValueByMeasurementFrequency, us-gaap:OptionIndexedToIssuersEquityType

us-gaap:FairValueMeasurementsRecurring, us-gaap:CallOption


Financial
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value0.1670.0811.3561.9773.1540.0770.2370.4050.7160.0030.5890.780.123
Percentage of FinancialLiabilitiesFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value656464646463636261595857555453515049474644434140383737363533323029272624232119181613
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value52525252525252515048474645444342414039383635343331302928262524232220191817151413129.767
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization81.181.381.481.681.882.082.282.181.981.881.781.781.881.881.981.982.082.082.182.182.182.182.182.182.182.178.377.076.776.576.276.075.675.374.974.674.273.973.473.072.571.8

us-gaap:TechnologyEquipment


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value4.34.34.34.34.34.34.34.34.34.34.34.1934.0853.9783.873.7623.6553.5473.443.3323.2253.1183.012.9022.7952.6882.582.4722.3652.2572.151.7251.7251.8271.721.6121.5051.3981.29
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization6.66.66.76.76.76.76.86.97.07.27.37.37.37.37.37.27.27.27.27.27.27.27.27.27.27.26.96.86.76.76.75.65.96.66.66.56.56.56.5

us-gaap:TradeNames


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value8.0217.867.77.547.3797.2197.0586.8986.7386.5776.4176.2566.0965.9355.7755.6155.4545.2945.1334.9734.8134.6524.4914.3314.1714.013.853.693.5293.3693.2083.0482.8882.7272.5672.4062.2462.0851.9251.7651.6041.283
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization12.312.111.911.711.511.311.111.111.011.010.910.910.910.910.810.810.810.810.710.710.710.710.710.710.710.710.310.110.010.010.010.09.99.99.89.89.79.79.69.69.59.4

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive


Finite
Period End2020-12-312020-09-30
Value5275000.05133000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths


Finite
Period End2021-06-302021-03-312020-12-31
Value1043000.01043000.01067000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear


Finite
Period End2021-06-302021-03-312020-09-30
Value534000.0800000.0226000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive


Finite
Period End2020-12-312020-09-30
Value807000.0686000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearFive100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour


Finite
Period End2021-06-302021-03-312020-12-312020-09-30
Value807000.0807000.0851000.0714000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearFour100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree


Finite
Period End2021-06-302021-03-312020-12-312020-09-30
Value851000.0851000.0879000.0878000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearThree100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo


Finite
Period End2021-06-302021-03-312020-12-312020-09-30
Value879000.0879000.01043000.0902000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo100.0100.0100.0100.0

us-gaap:IncomeTaxExaminationPenaltiesAndInterestAccrued

us-gaap:IncomeTaxExaminationPenaltiesAndInterestAccrued


Income
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value3100000.02800000.02900000.02417000.03521000.02915000.02803000.02065000.0945000.0834000.0728000.0
Percentage of IncomeTaxExaminationPenaltiesAndInterestAccrued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeTaxesReceivable

us-gaap:IncomeTaxesReceivable


Income
Period End2021-06-302020-06-302020-03-312019-12-31
Value623000.0007642000.0
Percentage of IncomeTaxesReceivable100.00.00.0100.0

us-gaap:IntangibleAssetsGrossExcludingGoodwill

us-gaap:IntangibleAssetsGrossExcludingGoodwill


Intangible
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value757575747474747474747474747473737373737373737372727271
Percentage of IntangibleAssetsGrossExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IntangibleAssetsGrossExcludingGoodwill us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships


Intangible
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value545454535353535353535353535352525252525252525251515151
Percentage of IntangibleAssetsGrossExcludingGoodwill72.272.272.271.671.671.671.671.671.671.671.571.571.571.571.571.371.371.371.371.371.371.371.371.071.071.072.4

us-gaap:Investments

us-gaap:Investments


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value50404946472945484402415743124218416540613768390438343724373237273659360035473554348734333380334833593443340334073389331631583126317632043180316031133119306230373117302531553146
Percentage of Investments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Investments us-gaap:ConsolidatedEntities

srt:ParentCompany


Investmentsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-31
Value2400215219722138
Percentage of Investments50.849.952.457.3

us-gaap:InvestmentsFairValueDisclosure us-gaap:FinancialInstrument

us-gaap:InvestmentsFairValueDisclosure

us-gaap:FinanceReceivables


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value5.6985.7125.7255.7365.6975.6985.6655.6535.6355.5885.5575.5145.5165.565
Percentage of InvestmentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Investments


Investments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302011-12-31
Value50404946472945484402415743124218416540613768390438343724373237273659360035473554348734333380334833593443340334073389331631583126317632043180316031133062
Percentage of InvestmentsFairValueDisclosure88466.286593.282607.379302.677271.572956.876119.374617.973913.172677.667808.070802.869509.70.067075.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesFairValueDisclosure us-gaap:ConsolidatedEntities

us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesFairValueDisclosure

srt:ParentCompany


Investments
Period End2020-12-312019-12-312018-12-312017-12-31
Value2285200818501976
Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesFairValueDisclosure100.0100.0100.0100.0

us-gaap:LesseeFinanceLeaseDiscountRate

us-gaap:LesseeFinanceLeaseDiscountRate


Lessee
Period End2020-12-31
Value0.82
Percentage of LesseeFinanceLeaseDiscountRate100.0

us-gaap:LesseeOperatingLeaseDiscountRate

us-gaap:LesseeOperatingLeaseDiscountRate


Lessee
Period End2020-12-312019-12-31
Value2.823.02
Percentage of LesseeOperatingLeaseDiscountRate100.0100.0

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths


Lessee
Period End2020-12-31
Value15
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths100.0

us-gaap:LiabilityForCatastropheClaimsCarryingAmount us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent

us-gaap:LiabilityForCatastropheClaimsCarryingAmount

us-gaap:Catastrophe


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-03-312018-12-312018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value64396948184.05711289119.01685940302723198.01911
Percentage of LiabilityForCatastropheClaimsCarryingAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpense


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312013-12-312012-12-31
Value20912041199119411865189719211855178317871829158015491530151013721326131612901244121011741146109110381036
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpensePropertyCasualtyLiability

us-gaap:LiabilityForClaimsAndClaimsAdjustmentExpensePropertyCasualtyLiability


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2091204119911941186518971921185517831787182915801549153015101372132613161290124412101174114611311113110510911062105310441038101010071009103697897895498597898099010341053
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpensePropertyCasualtyLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet

us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value20381986193618871815182818451751167616591648153015031478144613611315130412771230119611601132107710251023977102710451127
Percentage of LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity us-gaap:AssetsSoldUnderAgreementsToRepurchase, us-gaap:CreditFacility

us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity

mcy:UnsecuredNotesTwo, us-gaap:RevolvingCreditFacility


Line
Period End2021-03-312017-03-29
Value7550
Percentage of LineOfCreditFacilityMaximumBorrowingCapacity100.0100.0

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive


Long
Period End2020-12-31
Value375
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive100.0

us-gaap:NotesPayable

us-gaap:NotesPayable


Notes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value372372372372372372372372371371371371371371371371371371320290290290290290290290290290270270190180140140140140140140140138263265267271
Percentage of NotesPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:NotesPayable us-gaap:ConsolidatedEntities

srt:ParentCompany


Notes
Period End2020-12-312019-12-312018-12-312017-12-31
Value372372371371
Percentage of NotesPayable100.0100.0100.0100.0

us-gaap:NotesPayable us-gaap:FinancialInstrument, us-gaap:LongtermDebtType

us-gaap:Borrowings, us-gaap:UnsecuredDebt


Notes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value372372372372372372372372371371371371371371371371371371180
Percentage of NotesPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.056.2

us-gaap:NotesPayableFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType

us-gaap:NotesPayableFairValueDisclosure

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:Borrowings, us-gaap:UnsecuredDebt


Notes
Period End2021-06-302021-03-312020-12-31
Value423422415
Percentage of NotesPayableFairValueDisclosure100.0100.0100.0

us-gaap:NotesPayableFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType

us-gaap:FairValueInputsLevel2, us-gaap:Borrowings, us-gaap:UnsecuredDebt


Notes
Period End2020-12-312019-12-312018-12-312017-12-31
Value415394362385
Percentage of NotesPayableFairValueDisclosure100.00.00.00.0

us-gaap:NotesPayableFairValueDisclosure us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, us-gaap:LongtermDebtType

us-gaap:FairValueMeasurementsRecurring, us-gaap:Borrowings, us-gaap:UnsecuredDebt


Notes
Period End2021-06-302021-03-312020-12-31
Value423422415
Percentage of NotesPayableFairValueDisclosure100.0100.0100.0

us-gaap:NotesPayableFairValueDisclosure us-gaap:FinancialInstrument, us-gaap:LongtermDebtType

us-gaap:Borrowings, us-gaap:UnsecuredDebt


Notes
Period End2020-12-312019-12-312018-12-31
Value415394362
Percentage of NotesPayableFairValueDisclosure100.00.00.0

us-gaap:OtherLiabilities

us-gaap:OtherLiabilities


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value294285236246219234221233267267263240240256224242250202229226203224199192179208207163163187170182193168153160157163149182184180167177
Percentage of OtherLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherLiabilities us-gaap:ConsolidatedEntities

srt:ParentCompany


Other
Period End2020-12-312019-12-312018-12-312017-12-31
Value4.864.95.364.916
Percentage of OtherLiabilities2.12.22.02.2

us-gaap:OtherReceivables

us-gaap:OtherReceivables


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value106.67510108.4217.8316.4645.5545.2526.336.1326.0776.1526.9786.6581818232422232121212121212221212318171617121111111011101013
Percentage of OtherReceivables100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherShortTermInvestments

us-gaap:OtherShortTermInvestments


Other
Period End2021-06-302021-03-312020-12-31
Value408548375
Percentage of OtherShortTermInvestments100.0100.0100.0

us-gaap:PremiumsAndOtherReceivablesNet

us-gaap:PremiumsAndOtherReceivablesNet


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value666666642674653674651676640630606612579558520546532543524538525527501504478479449456445450425426407418394391361355332342333342327327
Percentage of PremiumsAndOtherReceivablesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PremiumsReceivableAllowanceForDoubtfulAccounts

us-gaap:PremiumsReceivableAllowanceForDoubtfulAccounts


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value6000000.07000000.010000000.010000000.010000000.010000000.01445000.01313000.01199000.01321000.01458000.01258000.0
Percentage of PremiumsReceivableAllowanceForDoubtfulAccounts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PremiumsReceivableAllowanceForDoubtfulAccounts us-gaap:CumulativeEffectPeriodOfAdoption

srt:CumulativeEffectPeriodOfAdoptionAdjustedBalance


Premiums
Period End2021-03-312020-12-312020-03-312019-12-312018-12-312017-12-31
Value7000000.010000000.010000000.03300000.01458000.01258000.0
Percentage of PremiumsReceivableAllowanceForDoubtfulAccounts100.0100.0100.0228.4100.0100.0

us-gaap:PremiumsReceivableAtCarryingValue

us-gaap:PremiumsReceivableAtCarryingValue


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value615616589621602623604629592579555558527509474485469478459474460465436442413417390395384392366372356368345346317309288298287296280276
Percentage of PremiumsReceivableAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PremiumsReceivableGross

us-gaap:PremiumsReceivableGross


Premiums
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value621623599631612633606
Percentage of PremiumsReceivableGross100.0100.0100.0100.0100.0100.0100.0

us-gaap:RatioOfIndebtednessToNetCapital1

us-gaap:RatioOfIndebtednessToNetCapital1


Ratio
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value14.715.116.50.1710.1880.1720.1750.1790.1780.18
Percentage of RatioOfIndebtednessToNetCapital1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RatioOfIndebtednessToNetCapital1 us-gaap:Range, us-gaap:AssetsSoldUnderAgreementsToRepurchase, us-gaap:CreditFacility

srt:Maximum, mcy:UnsecuredNotesTwo, us-gaap:RevolvingCreditFacility


Ratio
Period End2020-12-312019-12-312018-12-312017-03-29
Value15.60.1720.1880.25
Percentage of RatioOfIndebtednessToNetCapital10.00.00.00.0

us-gaap:ReinsuranceReceivablesCaseBasis

us-gaap:ReinsuranceReceivablesCaseBasis


Reinsurance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value525448415070781031261142215347525613
Percentage of ReinsuranceReceivablesCaseBasis100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments

us-gaap:ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments


Reinsurance
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value54761806413
Percentage of ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments100.0100.0100.0100.0100.0

us-gaap:ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments us-gaap:ProductOrService

mcy:PropertyInsuranceProductLineAutomobile


Reinsurance
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1822411012
Percentage of ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments33.429.022.815.695.8

mcy:PropertyInsuranceProductLineHomeowners


Reinsurance
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value3552138530.199
Percentage of ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments64.768.776.483.31.5

us-gaap:OtherShortdurationInsuranceProductLine


Reinsurance
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1.0591.7231.4470.6740.36
Percentage of ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments1.92.30.81.12.7

us-gaap:ReinsuranceRecoverablesAllowance

us-gaap:ReinsuranceRecoverablesAllowance


Reinsurance
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-06-302019-03-312018-12-31
Value91000.058000.088000.0148000.00000
Percentage of ReinsuranceRecoverablesAllowance100.0100.0100.0100.00.00.00.00.0

us-gaap:ReinsuranceRecoverablesAllowance us-gaap:CumulativeEffectPeriodOfAdoption

srt:CumulativeEffectPeriodOfAdoptionAdjustedBalance


Reinsurance
Period End2020-12-312020-03-312019-12-31
Value91000.0148000.0159000.0
Percentage of ReinsuranceRecoverablesAllowance100.0100.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value43.0143.0141.7844.7248.7349.5851.8650.3748.5948.45
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

mcy:ExercisePriceRangeOne


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value43.0143.0135.4842.6441.443.0943.86
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice100.0100.084.995.385.086.984.6

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue


Share
Period End2020-12-31
Value621000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue100.0

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1


Sharebased
Period End2020-12-31
Value299000.0
Percentage of SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1100.0

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue

us-gaap:EmployeeStockOption


Sharebased
Period End2020-12-31
Value8.09
Percentage of SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue100.0

us-gaap:ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1469514567141281386013862
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value24152190200218521667
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet16.415.014.213.412.0

us-gaap:ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet us-gaap:ProductOrService, us-gaap:ShortdurationInsuranceContractsAccidentYear

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractAccidentYear2019


Shortduration
Period End2020-12-312019-12-31
Value14941134
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet10.27.8

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractAccidentYear2020


Shortduration
Period End2020-12-31
Value825
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet5.6

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractsAccidentYear2017


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-31
Value1648156113991076
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet11.210.79.97.8

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractsAccidentYear2018


Shortduration
Period End2020-12-312019-12-312018-12-31
Value158814171082
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet10.89.77.7

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2011


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value140114901460142213911378134712771152926
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet9.510.210.310.310.00.00.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2012


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value14401614147614471409137213041194955
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet9.811.110.510.410.20.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2013


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value1466165615601432141313401217974
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet10.011.411.010.310.20.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2014


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value149615611554146613581231967
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet10.210.711.010.69.80.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2015


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value163414171399139513361040
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet11.19.79.910.19.60.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2016


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value16991134108210761094
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet11.67.87.77.87.9

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractAccidentYear2019


Shortduration
Period End2020-12-312019-12-31
Value324240
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet2.21.6

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractAccidentYear2020


Shortduration
Period End2020-12-31
Value271
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.8

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractsAccidentYear2017


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-31
Value283278269217
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.91.91.91.6

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractsAccidentYear2018


Shortduration
Period End2020-12-312019-12-312018-12-31
Value286271213
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet2.01.91.5

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2011


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value169203186190168167166162153111
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.21.41.31.41.20.00.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2012


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value192234202185190188182175128
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.31.61.41.31.40.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2013


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value186253230198183180174133
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.31.71.61.41.30.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2014


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value207278245224194186139
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.41.91.71.61.40.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2015


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value235271269234213163
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.61.91.91.71.50.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2016


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value256240213217173
Percentage of ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet1.71.61.51.61.3

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.30.0030.0030.0010.001
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.30.0040.00200
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearEight100.0133.366.70.00.0

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value2.60.0260.0250.0230.022
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1.20.0120.01100.01
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFive46.246.244.00.045.5

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value5.20.0520.050.050.049
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value2.30.0260.02600.03
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearFour44.250.052.00.061.2

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.10.0090.00100.001
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine100.0100.0100.00.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.10.0050.00100.001
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearNine100.055.6100.00.0100.0

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value62.60.6360.6470.6580.66
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value67.90.6760.67300.661
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearOne108.5106.3104.00.0100.2

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.50.0050.0060.0040.004
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.70.0040.00300.002
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSeven140.080.050.00.050.0

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1.00.0090.0080.0070.007
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.40.0050.00700.007
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearSix40.055.687.50.0100.0

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value8.70.0860.0870.0850.085
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value4.10.0440.04700.046
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearThree47.151.254.00.054.1

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value17.60.1740.1730.1710.171
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value21.90.2240.2300.243
Percentage of ShortdurationInsuranceContractsHistoricalClaimsDurationYearTwo124.4128.7132.90.0142.1

us-gaap:ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet us-gaap:ProductOrService, us-gaap:ShortdurationInsuranceContractsAccidentYear

us-gaap:ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractAccidentYear2019


Shortduration
Period End2020-12-31
Value165
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet100.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractAccidentYear2020


Shortduration
Period End2020-12-31
Value407
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet247.1

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractsAccidentYear2017


Shortduration
Period End2020-12-31
Value22
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet13.7

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractsAccidentYear2018


Shortduration
Period End2020-12-31
Value60
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet36.8

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2011


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.0593.4692.8181.7564.069
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet0.00.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2012


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.1169.1326.6264.0114.531
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet0.10.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2013


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.81622191210
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet0.50.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2014


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.71858504032
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet0.40.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2015


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value4.57713913310290
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet2.80.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2016


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value8.206438390347303
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet5.00.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractAccidentYear2019


Shortduration
Period End2020-12-31
Value17
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet10.6

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractAccidentYear2020


Shortduration
Period End2020-12-31
Value77
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet46.9

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractsAccidentYear2017


Shortduration
Period End2020-12-31
Value2.702
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet1.6

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractsAccidentYear2018


Shortduration
Period End2020-12-31
Value9.704
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet5.9

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2011


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.1673.2590.780.4280.325
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet0.10.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2012


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.121.9781.3410.5240.585
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet0.10.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2013


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.1422.0923.1311.330.775
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet0.10.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2014


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value0.5924.316.5254.3682.993
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet0.40.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2015


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value2.9515129.9959.431
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet1.80.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2016


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1.82164594736
Percentage of ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet1.10.00.00.00.0

us-gaap:ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1613816007154231500214879
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value26472372215319871780
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet16.414.814.013.212.0

us-gaap:ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet us-gaap:ProductOrService, us-gaap:ShortdurationInsuranceContractsAccidentYear

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractAccidentYear2019


Shortduration
Period End2020-12-312019-12-31
Value19111916
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet11.812.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractAccidentYear2020


Shortduration
Period End2020-12-31
Value1514
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet9.4

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractsAccidentYear2017


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-31
Value1733174117271703
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet10.710.911.211.4

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractsAccidentYear2018


Shortduration
Period End2020-12-312019-12-312018-12-31
Value178517731781
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet11.111.111.6

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2011


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value1401150114681436139813931388138013671343
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet8.79.49.59.69.40.00.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2012


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value144016451498146414261414140914081424
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet8.910.39.79.89.60.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2013


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value14681731163414861458144714311448
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet9.110.810.69.99.80.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2014


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value1501174117131610147314541467
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet9.310.911.110.79.90.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2015


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value164917731727166915881551
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet10.211.111.211.110.70.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2016


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value17321916178117031672
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet10.712.011.611.411.2

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractAccidentYear2019


Shortduration
Period End2020-12-312019-12-31
Value366359
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet2.32.2

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractAccidentYear2020


Shortduration
Period End2020-12-31
Value420
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet2.6

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractsAccidentYear2017


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-31
Value289288295309
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet1.81.81.92.1

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractsAccidentYear2018


Shortduration
Period End2020-12-312019-12-312018-12-31
Value310308311
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet1.91.92.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2011


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value170208188191169169169170170167
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet1.11.31.21.31.10.00.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2012


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value193238204187192191190188196
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet1.21.51.31.21.30.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2013


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value187259236202186188188191
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet1.21.61.51.31.30.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2014


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value208288259233203202199
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet1.31.81.71.61.40.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2015


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value239308295259234234
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet1.51.91.91.71.60.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2016


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value260359311309250
Percentage of ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet1.62.22.02.11.7

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value18201745155513591196
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet100.0100.0100.0100.0100.0

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet us-gaap:ProductOrService

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value14421439129411411016
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet79.382.583.283.985.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value233182154137116
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet12.810.59.910.19.7

mcy:PropertyInsuranceProductLineWAICAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1316171212
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet0.80.91.10.91.0

us-gaap:OtherShortdurationInsuranceProductLine


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value130106906951
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNet7.26.15.85.14.3

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented us-gaap:ProductOrService

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented

mcy:PropertyInsuranceProductLineAutomobile


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value-531000.0557000.0-505000.0-169000.0-212000.0
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented100.0100.0100.0100.0100.0

mcy:PropertyInsuranceProductLineHomeowners


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1457000.0576000.02416000.02141000.02661000.0
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndAllocatedClaimAdjustmentExpenseNetNotSeparatelyPresented-274.4103.4-478.4-1266.9-1255.2

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimAdjustmentExpenseAggregateReconcilingItems

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimAdjustmentExpenseAggregateReconcilingItems


Shortduration
Period End2020-12-31
Value116
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimAdjustmentExpenseAggregateReconcilingItems100.0

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimAdjustmentExpenseOtherReconcilingItem

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimAdjustmentExpenseOtherReconcilingItem


Shortduration
Period End2020-12-31
Value676000.0
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimAdjustmentExpenseOtherReconcilingItem100.0

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense

us-gaap:ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense


Shortduration
Period End2020-12-31
Value116
Percentage of ShortdurationInsuranceContractsLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseAccumulatedUnallocatedClaimAdjustmentExpense100.0

us-gaap:ShortdurationInsuranceContractsNumberOfReportedClaims us-gaap:ProductOrService, us-gaap:ShortdurationInsuranceContractsAccidentYear

us-gaap:ShortdurationInsuranceContractsNumberOfReportedClaims

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractAccidentYear2019


Shortduration
Period End2020-12-31
Value147000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims100.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractAccidentYear2020


Shortduration
Period End2020-12-31
Value85000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims57.8

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractsAccidentYear2017


Shortduration
Period End2020-12-31
Value149000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims101.4

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortDurationInsuranceContractsAccidentYear2018


Shortduration
Period End2020-12-31
Value146000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims99.3

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2011


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value181000.0180000.0185000.0180650.0181000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims123.10.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2012


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value181000.0170000.0180000.0184560.0181000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims123.10.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2013


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value185000.0154000.0170000.0180410.0185000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims125.90.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2014


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value180000.0149000.0154000.0170000.0180000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims122.40.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2015


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value170000.0146000.0148000.0153780.0169000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims115.60.00.00.00.0

mcy:PropertyInsuranceProductLineAutomobile, us-gaap:ShortdurationInsuranceContractsAccidentYear2016


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value155000.0140000.0139000.0140220.0145000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims105.40.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractAccidentYear2019


Shortduration
Period End2020-12-31
Value30000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims20.4

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractAccidentYear2020


Shortduration
Period End2020-12-31
Value26000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims17.7

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractsAccidentYear2017


Shortduration
Period End2020-12-31
Value30000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims20.4

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortDurationInsuranceContractsAccidentYear2018


Shortduration
Period End2020-12-31
Value25000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims17.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2011


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value23000.025000.023000.024621.023000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims15.60.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2012


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value25000.024000.025000.023436.025000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims17.00.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2013


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value23000.024000.024000.024826.023000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims15.60.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2014


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value25000.030000.024000.023955.025000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims17.00.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2015


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value24000.025000.030000.024254.024000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims16.30.00.00.00.0

mcy:PropertyInsuranceProductLineHomeowners, us-gaap:ShortdurationInsuranceContractsAccidentYear2016


Shortduration
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value24000.028000.023000.028182.023000.0
Percentage of ShortdurationInsuranceContractsNumberOfReportedClaims16.30.00.00.00.0

us-gaap:StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithoutRegulatoryApproval

us-gaap:StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithoutRegulatoryApproval


Statutory
Period End2020-12-31
Value222
Percentage of StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithoutRegulatoryApproval100.0

us-gaap:StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance

us-gaap:StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance


Statutory
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value176815391471158914411451143815281440149713221517
Percentage of StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount


Summary
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value47294312376837323547338034033158318030623155
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount us-gaap:FinancialInstrument

mcy:PrivateEquityFundsNetAssetValue


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value7987651.481
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount1.72.01.70.0

us-gaap:CollateralizedDebtObligations


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value256199165105
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount5.44.64.42.8

us-gaap:CommonStock


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value691586430429
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount14.613.611.411.5

us-gaap:CorporateDebtSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value241235105137
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount5.15.52.83.7

us-gaap:EquitySecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value803724529537
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount17.016.814.114.4

us-gaap:FixedIncomeSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value3549309329852892
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount75.171.779.277.5

us-gaap:MortgageBackedSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value93633027
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount2.01.50.80.7

us-gaap:MunicipalBonds


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value2791255426202556
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount59.059.269.568.5

us-gaap:NonredeemablePreferredStock


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value32493134
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount0.71.20.80.9

us-gaap:OtherDebtSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value153183753
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount3.20.41.01.4

us-gaap:ShortTermInvestments


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value375494253302
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount7.911.56.78.1

us-gaap:USGovernmentAgenciesDebtSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value13222513
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount0.30.50.70.4

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost


Summary
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value44604115376836003502330332643062304129703097
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost us-gaap:FinancialInstrument

mcy:PrivateEquityFundsNetAssetValue


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value10099691.481
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost2.22.41.80.0

us-gaap:CollateralizedDebtObligations


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value256200169104
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost5.84.94.52.9

us-gaap:CommonStock


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value563498438368
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost12.612.111.610.2

us-gaap:CorporateDebtSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value240233107136
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost5.45.72.93.8

us-gaap:EquitySecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value695648544474
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost15.615.814.413.2

us-gaap:FixedIncomeSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value3388297329692823
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost76.072.278.878.4

us-gaap:MortgageBackedSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value91623026
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost2.11.50.80.7

us-gaap:MunicipalBonds


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value2632243525992490
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost59.059.269.069.2

us-gaap:NonredeemablePreferredStock


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value31493434
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost0.71.20.91.0

us-gaap:OtherDebtSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value153183752
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost3.40.41.01.5

us-gaap:ShortTermInvestments


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value376494254302
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost8.412.06.88.4

us-gaap:USGovernmentAgenciesDebtSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value13222513
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost0.30.50.70.4

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue


Summary
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value47294312376837323547338034033158318030623155
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue us-gaap:FinancialInstrument

mcy:PrivateEquityFundsNetAssetValue


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value7987651.481
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue1.72.01.70.0

us-gaap:CollateralizedDebtObligations


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value256199165105
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue5.44.64.42.8

us-gaap:CommonStock


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value691586430429
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue14.613.611.411.5

us-gaap:CorporateDebtSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value241235105137
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue5.15.52.83.7

us-gaap:EquitySecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value803724529537
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue17.016.814.114.4

us-gaap:FixedIncomeSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value3549309329852892
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue75.171.779.277.5

us-gaap:MortgageBackedSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value93633027
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue2.01.50.80.7

us-gaap:MunicipalBonds


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value2791255426202556
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue59.059.269.568.5

us-gaap:NonredeemablePreferredStock


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value32493134
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue0.71.20.80.9

us-gaap:OtherDebtSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value153183753
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue3.20.41.01.4

us-gaap:ShortTermInvestments


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value375494253302
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue7.911.56.78.1

us-gaap:USGovernmentAgenciesDebtSecurities


Summary
Period End2020-12-312019-12-312018-12-312017-12-31
Value13222513
Percentage of SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue0.30.50.70.4

us-gaap:TaxesPayableCurrentAndNoncurrent us-gaap:ConsolidatedEntities

us-gaap:TaxesPayableCurrentAndNoncurrent

srt:ParentCompany


Taxes
Period End2020-12-312019-12-312018-12-312017-12-31
Value1014170.0
Percentage of TaxesPayableCurrentAndNoncurrent100.0100.0100.00.0

us-gaap:TradingSecurities us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FinancialInstrument

us-gaap:TradingSecurities

us-gaap:FairValueInputsLevel2, us-gaap:CommercialMortgageBackedSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value2517171212181821172224252519
Percentage of TradingSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TradingSecuritiesDebt

us-gaap:TradingSecuritiesDebt


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value37613587354934853327329930933139315730772985295229492929289228412952291428142972293929422880288628902888261826192704263325602538248225132408246824872485244524662556251926522704
Percentage of TradingSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TradingSecuritiesDebt us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value141313242323222323232513
Percentage of TradingSecuritiesDebt0.40.40.40.70.70.70.70.70.80.80.80.5

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value374735733535346133033275307031163133305329602879
Percentage of TradingSecuritiesDebt99.699.699.699.399.399.399.399.399.299.299.299.5

us-gaap:TradingSecuritiesDebt us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring, us-gaap:USGovernmentAgenciesDebtSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value141313242323222323232513
Percentage of TradingSecuritiesDebt0.40.40.40.70.70.70.70.70.80.80.80.5

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, mcy:MunicipalSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value284528252791277327272720255426502713269526202556
Percentage of TradingSecuritiesDebt75.778.878.679.682.082.482.684.485.987.687.888.4

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, mcy:OtherAssetBackedSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value2471711531083417182843393753
Percentage of TradingSecuritiesDebt6.64.84.33.11.10.50.60.91.41.31.31.8

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:CollateralizedLoanObligations


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value278267256257199184199173172172165105
Percentage of TradingSecuritiesDebt7.47.57.27.46.05.66.45.55.55.65.63.6

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:CorporateDebtSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value283226241251262269235221181118105137
Percentage of TradingSecuritiesDebt7.56.36.87.27.98.27.67.15.83.83.54.8

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:MortgageBackedSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value928293707883634222283027
Percentage of TradingSecuritiesDebt2.52.32.62.02.42.52.01.40.70.91.00.9

us-gaap:TradingSecuritiesDebt us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value376135873549348533273299309331393157307729852892
Percentage of TradingSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TradingSecuritiesDebt us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument

us-gaap:FairValueMeasurementsRecurring, mcy:MunicipalSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value284528252791277327272720255426502713269526202556
Percentage of TradingSecuritiesDebt75.778.878.679.682.082.482.684.485.987.687.888.4

us-gaap:FairValueMeasurementsRecurring, mcy:OtherAssetBackedSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value2471711531083417182843393753
Percentage of TradingSecuritiesDebt6.64.84.33.11.10.50.60.91.41.31.31.8

us-gaap:FairValueMeasurementsRecurring, us-gaap:CollateralizedLoanObligations


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value278267256257199184199173172172165105
Percentage of TradingSecuritiesDebt7.47.57.27.46.05.66.45.55.55.65.63.6

us-gaap:FairValueMeasurementsRecurring, us-gaap:CorporateDebtSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value283226241251262269235221181118105137
Percentage of TradingSecuritiesDebt7.56.36.87.27.98.27.67.15.83.83.54.8

us-gaap:FairValueMeasurementsRecurring, us-gaap:MortgageBackedSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value928293707883634222283027
Percentage of TradingSecuritiesDebt2.52.32.62.02.42.52.01.40.70.91.00.9

us-gaap:FairValueMeasurementsRecurring, us-gaap:USGovernmentAgenciesDebtSecurities


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value141313242323222323232513
Percentage of TradingSecuritiesDebt0.40.40.40.70.70.70.70.70.80.80.80.5

us-gaap:UnamortizedDebtIssuanceExpense

us-gaap:UnamortizedDebtIssuanceExpense


Unamortized
Period End2021-06-302021-03-312020-09-30
Value200000.0200000.0100000.0
Percentage of UnamortizedDebtIssuanceExpense100.0100.0100.0

us-gaap:UnearnedPremiums

us-gaap:UnearnedPremiums


Unearned
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value147114401405143213901384135513831314127312361240119011501101111910931094107411021080107810491063102610259991012993993953967938948920921882865843866847853833844
Percentage of UnearnedPremiums100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate

us-gaap:UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate


Unrecognized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value6.27.211101110118.43.53.63.0
Percentage of UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Line plots across dimensions of each concept


us-gaap:PolicyholderBenefitsAndClaimsIncurredNet
us-gaap:StatementBusinessSegments
(None,)
Policyholder Benefits And Claims Incurred Netus-gaap: Statement Business Segments
us-gaap:PremiumsEarnedNet
us-gaap:StatementBusinessSegments
(None,)
Premiums Earned Netus-gaap: Statement Business Segments
us-gaap:PremiumsEarnedNet
us-gaap:ProductOrService
(None,)
Premiums Earned Netus-gaap: Product Or Service
us-gaap:ShortTermInvestments
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
(None, 'us-gaap:FairValueMeasurementsRecurring')
Short Term Investmentsus-gaap: Fair Value By Fair Value Hierarchy Level, us-gaap: Fair Value By Measurement Frequency
us-gaap:ShortTermInvestments
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument
('us-gaap:FairValueInputsLevel1', 'us-gaap:FairValueMeasurementsRecurring', None)
Short Term Investmentsus-gaap: Fair Value By Fair Value Hierarchy Level, us-gaap: Fair Value By Measurement Frequency, us-gaap: Financial Instrument
us-gaap:ShortTermInvestments
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument
('us-gaap:FairValueMeasurementsRecurring', None)
Short Term Investmentsus-gaap: Fair Value By Measurement Frequency, us-gaap: Financial Instrument
us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType
(None,)
Property Plant And Equipment Grossus-gaap: Property Plant And Equipment By Type
us-gaap:IntangibleAssetsNetExcludingGoodwill
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
(None,)
Intangible Assets Net Excluding Goodwillus-gaap: Finite Lived Intangible Assets By Major Class
us-gaap:EquitySecuritiesFvNi
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
(None, 'us-gaap:FairValueMeasurementsRecurring')
Equity Securities Fv Nius-gaap: Fair Value By Fair Value Hierarchy Level, us-gaap: Fair Value By Measurement Frequency
us-gaap:EquitySecuritiesFvNi
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument
('us-gaap:FairValueMeasurementsRecurring', None)
Equity Securities Fv Nius-gaap: Fair Value By Measurement Frequency, us-gaap: Financial Instrument
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
us-gaap:StatementEquityComponents
(None,)
Stockholders Equity Including Portion Attributable To Noncontrolling Interestus-gaap: Statement Equity Components