MKTX


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

Table of contents



us-gaap:CommonStockValue
us-gaap:ConsolidatedEntities
us-gaap:StatementClassOfStock
us-gaap:CommonStockSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

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

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:AllocatedShareBasedCompensationExpense
us-gaap:TitleOfIndividual

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:GeneralAndAdministrativeExpense

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

us-gaap:IncomeTaxExpenseBenefit

us-gaap:InterestExpense
us-gaap:CreditFacility
us-gaap:InterestExpenseDebt
us-gaap:FinancialInstrument
us-gaap:Range, us-gaap:FinancialInstrument

us-gaap:MarketingAndAdvertisingExpense

us-gaap:NetIncomeLoss
us-gaap:StatementEquityComponents

us-gaap:NonoperatingIncomeExpense

us-gaap:OperatingExpenses

us-gaap:OperatingIncomeLoss

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:ProductOrService
us-gaap:ProductOrService, us-gaap:TimingOfTransferOfGoodOrService
us-gaap:StatementGeographical

us-gaap:Revenues

us-gaap:Assets
us-gaap:ConsolidatedEntities

us-gaap:Liabilities
us-gaap:ConsolidatedEntities

us-gaap:LiabilitiesAndStockholdersEquity
us-gaap:ConsolidatedEntities

us-gaap:StockholdersEquity
us-gaap:ConsolidatedEntities
us-gaap:StatementEquityComponents

us-gaap:CashAndCashEquivalentsAtCarryingValue
us-gaap:BalanceSheetLocation
us-gaap:ConsolidatedEntities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AmortizationOfIntangibleAssets

us-gaap:PropertyPlantAndEquipmentNet
us-gaap:ConsolidatedEntities
us-gaap:StatementGeographical

us-gaap:Goodwill
us-gaap:BusinessAcquisition

us-gaap:IntangibleAssetsNetExcludingGoodwill
us-gaap:ConsolidatedEntities

us-gaap:FiniteLivedIntangibleAssetsNet
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FairValueByAssetClass
us-gaap:IntangibleAssetsNetIncludingGoodwill

us-gaap:OperatingLeaseRightOfUseAsset
us-gaap:ConsolidatedEntities

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:OperatingLeaseLiability
us-gaap:ConsolidatedEntities

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:StockholdersEquity
us-gaap:ConsolidatedEntities
us-gaap:StatementEquityComponents

us-gaap:CommonStockValue
us-gaap:ConsolidatedEntities

us-gaap:AdditionalPaidInCapitalCommonStock
us-gaap:ConsolidatedEntities

us-gaap:RetainedEarningsAccumulatedDeficit
us-gaap:ConsolidatedEntities

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
us-gaap:ConsolidatedEntities

us-gaap:TreasuryStockValue
us-gaap:ConsolidatedEntities

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:IncreaseDecreaseInAccountsReceivable

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss
us-gaap:StatementEquityComponents

us-gaap:ShareBasedCompensation

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:PaymentsForRepurchaseOfCommonStock

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxAssetsNet

us-gaap:UnrecognizedTaxBenefits

mktx:AdjustmentsRelatedToTaxWithholdingExpenseBenefitForShareBasedCompensation
us-gaap:StatementEquityComponents

mktx:AmortizationOfOperatingLeaseRightOfUseAssets

mktx:ContractWithCustomerLiabilityForeignCurrencyTranslation
us-gaap:ProductOrService

mktx:ContractWithCustomerLiabilityPaymentsReceived
us-gaap:ProductOrService

mktx:ContractWithCustomerLiabilityRevenueRecognizedIncludingAdditions
us-gaap:ProductOrService
us-gaap:ProductOrService
mktx:DisclosedTrading
us-gaap:ProductOrService
mktx:DistributionFeesAndUnusedMinimumFees

mktx:DividendsTreasuryStockCash
us-gaap:StatementEquityComponents

mktx:IncreaseDecreaseInOperatingLeaseLiabilities
us-gaap:IncomeStatementLocation
mktx:OperatingLeaseCostForSubleased

mktx:PaymentsToAcquireBusinessesNetOfCashAndCashEquivalentsAcquired

mktx:TransactionCosts
us-gaap:ProductOrService
mktx:VariableTransactionFees
us-gaap:BalanceSheetLocation, us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationConsiderationTransferred1
us-gaap:BusinessAcquisition

us-gaap:CommunicationsAndInformationTechnology
us-gaap:StatementGeographical, us-gaap:ConcentrationRiskByBenchmark, us-gaap:ConcentrationRiskByType
us-gaap:ConcentrationRiskPercentage1

us-gaap:ContractWithCustomerLiabilityRevenueRecognized
us-gaap:ProductOrService

us-gaap:CurrentFederalTaxExpenseBenefit

us-gaap:CurrentForeignTaxExpenseBenefit

us-gaap:CurrentIncomeTaxExpenseBenefit

us-gaap:CurrentStateAndLocalTaxExpenseBenefit

us-gaap:DeferredFederalIncomeTaxExpenseBenefit

us-gaap:DeferredForeignIncomeTaxExpenseBenefit

us-gaap:DeferredIncomeTaxesAndTaxCredits

us-gaap:DeferredStateAndLocalIncomeTaxExpenseBenefit

us-gaap:DepreciationAmortizationAndAccretionNet

us-gaap:DepreciationAndAmortization

us-gaap:DividendsCommonStockCash
us-gaap:StatementEquityComponents

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations

us-gaap:EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInBrokerageReceivables

us-gaap:IncreaseDecreaseInContractWithCustomerLiability

us-gaap:IncreaseDecreaseInEmployeeRelatedLiabilities

us-gaap:IncreaseDecreaseInIncomeTaxes

us-gaap:IncreaseDecreaseInPayablesToBrokerDealers

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

us-gaap:IncreaseDecreaseInTradingSecurities
us-gaap:InvestmentType

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements
us-gaap:ConsolidatedEntities, us-gaap:StatementGeographical
us-gaap:InterestExpenseShortTermBorrowings

us-gaap:InvestmentIncomeNonoperating

us-gaap:LaborAndRelatedExpense

us-gaap:LeaseCost

us-gaap:OccupancyNet
us-gaap:ProductOrService
us-gaap:OperatingLeaseCost

us-gaap:OtherComprehensiveIncomeForeignCurrencyTranslationGainLossArisingDuringPeriodTax

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax

us-gaap:OtherNoncashIncomeExpense

us-gaap:PaymentsOfOrdinaryDividends

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt
us-gaap:BalanceSheetLocation, us-gaap:BusinessAcquisition
us-gaap:PaymentsToAcquireBusinessesGross
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisition, us-gaap:SubsequentEventType

us-gaap:PaymentsToDevelopSoftware
us-gaap:ProductOrService
us-gaap:PrincipalTransactionsRevenue
us-gaap:ProductOrService, us-gaap:FinancialInstrument

us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities

us-gaap:ProceedsFromSaleAndMaturityOfMarketableSecurities

us-gaap:ProceedsFromShortTermDebt

us-gaap:ProceedsFromStockOptionsExercised

us-gaap:ProfessionalFees

us-gaap:RepaymentsOfSubordinatedDebt

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
us-gaap:TitleOfIndividual, us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
us-gaap:TitleOfIndividual, us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised
us-gaap:StatementEquityComponents

us-gaap:StockRepurchasedAndRetiredDuringPeriodValue
us-gaap:StatementEquityComponents
us-gaap:IncomeStatementLocation
us-gaap:SubleaseIncome
us-gaap:ShareRepurchaseProgram
us-gaap:TreasuryStockValueAcquiredCostMethod

us-gaap:UnrecognizedTaxBenefitsPeriodIncreaseDecrease
us-gaap:ProductOrService
us-gaap:VariableLeaseCost

mktx:DeferredTaxAssetsOperatingLeaseLiabilities

mktx:DeferredTaxLiabilitiesDepreciationAndAmortization

mktx:DeferredTaxLiabilitiesOperatingLeaseRightOfUseAssets
us-gaap:ConsolidatedEntities
mktx:InvestmentsInSubsidiaries

mktx:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFiveAndThereafter

mktx:MarketableSecuritiesAccumulatedGrossUnrealizedGainBeforeTax

mktx:MarketableSecuritiesAccumulatedGrossUnrealizedLossBeforeTax

mktx:MarketableSecuritiesAfterOneThroughFiveYearsFairValue

mktx:MarketableSecuritiesAmortizedCost

mktx:MarketableSecuritiesWithinOneYearFairValue
us-gaap:CreditFacility
mktx:MaximumPermittedInvestmentsAndLoansInBrokerDealerSubsidiary

mktx:MoneyMarketFundsFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel

mktx:MutualFundInvestmentsAndDeferredCompensationObligationAtFairValue
us-gaap:BalanceSheetLocation
mktx:OtherDeposits
us-gaap:ConsolidatedEntities
mktx:ReceivableFromSubsidiaries

mktx:ReceivablesFromBrokersDealersClearingOrganizationsAndCustomers

mktx:SecuritiesFailedToDeliverBrokerDealers

mktx:SecuritiesFailedToDeliverCustomers

mktx:SecuritiesFailedToReceiveBrokerDealers

mktx:SecuritiesFailedToReceiveCustomers

mktx:TradingSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
us-gaap:InvestmentType

mktx:TradingSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
us-gaap:InvestmentType

srt:AlternativeExcessNetCapital
us-gaap:CounterpartyName

srt:AlternativeNetCapitalRequirement1
us-gaap:CounterpartyName

srt:PayablesToBrokerDealersAndClearingOrganizations

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
us-gaap:ConsolidatedEntities

us-gaap:AccountsReceivableNet
us-gaap:ConsolidatedEntities

us-gaap:AllowanceForDoubtfulAccountsReceivable

us-gaap:AssetsFairValueDisclosure
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency
us-gaap:ConsolidatedEntities, us-gaap:StatementGeographical, us-gaap:BalanceSheetLocation
us-gaap:BankOverdrafts
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisitionCostOfAcquiredEntityTransactionCosts

us-gaap:BusinessCombinationContingentConsiderationLiability
us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent
us-gaap:BalanceSheetLocation, us-gaap:BusinessAcquisition
us-gaap:Range, us-gaap:BusinessAcquisition
us-gaap:Range, us-gaap:BusinessAcquisition, us-gaap:SubsequentEventType
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles

us-gaap:CashAndSecuritiesSegregatedUnderFederalAndOtherRegulations
us-gaap:BalanceSheetLocation

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations
us-gaap:ConsolidatedEntities

us-gaap:ContractWithCustomerLiability
us-gaap:ProductOrService

us-gaap:ContractualObligation
us-gaap:InvestmentType
us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months

us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost

us-gaap:DeferredTaxAssetsTaxDeferredExpenseOther

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssets

us-gaap:DepositsPaidForSecuritiesBorrowedAtCarryingValue
us-gaap:BalanceSheetLocation
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeAssetNotionalAmount
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral
us-gaap:DerivativeInstrumentRisk, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral
us-gaap:DerivativeInstrumentRisk, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeFairValueOfDerivativeNet
us-gaap:DerivativeInstrumentRisk, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeNotionalAmount

us-gaap:EmployeeRelatedLiabilitiesCurrentAndNoncurrent
us-gaap:ConsolidatedEntities

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
us-gaap:AwardType
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass, us-gaap:FairValueByMeasurementFrequency
us-gaap:FinancialLiabilitiesFairValueDisclosure
us-gaap:FairValueByLiabilityClass, us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByLiabilityClass, us-gaap:FairValueByMeasurementFrequency

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo

us-gaap:FiniteLivedIntangibleAssetsGross
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:ConsolidatedEntities
us-gaap:IncomeTaxReceivable

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear

us-gaap:LiabilitiesFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:CreditFacility
us-gaap:LineOfCreditFacilityCurrentBorrowingCapacity
us-gaap:CreditFacility
us-gaap:LineOfCreditFacilityRemainingBorrowingCapacity

us-gaap:MarketableSecurities
us-gaap:ConsolidatedEntities

us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent

us-gaap:OtherPayablesToBrokerDealersAndClearingOrganizations

us-gaap:OtherReceivablesFromBrokerDealersAndClearingOrganizations

us-gaap:PrepaidExpenseAndOtherAssets
us-gaap:ConsolidatedEntities

us-gaap:ReceivablesFromBrokersDealersAndClearingOrganizations

us-gaap:RevenueRemainingPerformanceObligation

us-gaap:SecuritiesReserveDepositRequiredAndMade
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1

us-gaap:TaxesPayableCurrentAndNoncurrent
us-gaap:ConsolidatedEntities

us-gaap:TradingSecuritiesDebt
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType
us-gaap:InvestmentType

us-gaap:TradingSecuritiesDebtAmortizedCost
us-gaap:InvestmentType

us-gaap:UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued

Plots across concepts


IncomeStatement
Net Income Loss
Expenses
Other Nonoperating Income Expense
Balance Sheet
Operating Lease Right Of Use Asset
Assets
Operating Lease Right Of Use Asset
Current Assets
Cash And Cash Equivalents At Carrying Value
NonCurrent Assets
Deferred Income Tax Assets Net
PropertyPlantAndEquipmentNet
Property Plant And Equipment Net
Liabilities
Accounts Payable And Accrued Liabilities Current And Noncurrent
Stockholders Equity
Accumulated Other Comprehensive Income Loss Net Of Tax
CashFlow
Net Cash Provided By Used In Financing Activities
NetCashProvidedByUsedInOperatingActivities
Increase Decrease In Accounts Receivable
NetCashProvidedByUsedInInvestingActivities
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInFinancingActivities
Net Cash Provided By Used In Financing Activities
Shares
Weighted Average Number Of Shares Outstanding Basic
DividendsAndRepurchase
Payments For Repurchase Of Common Stock
NonoperatingIncomeExpense
Nonoperating Income Expense
LesseeOperatingLeaseLiabilityPaymentsDue
Lessee Operating Lease Liability Payments Remainder Of Fiscal Year
FiniteLivedIntangibleAssets
Finite Lived Intangible Assets Accumulated Amortization

Tables

  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:CommonStockValue ███▁▁▁▁▁▁0.1230.1230.1230.1220.1220.1220.1220.1220.122NA0.122NANANANANANANANANANANANANANANANANA0.1190.1190.119NANANANANANANANANANANANANANA
 us-gaap:CommonStockSharesOutstanding us-gaap:StatementClassOfStock mktx:VotingCommonStockNANA38.005NANANA37.936NANANA37.64NANANA37.621NANANA37.544NANANA37.409NANANA39.46NANANA39.224NANANA38.902NANANA37.725NANANANANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding ▁█38.10438.155NA38.1638.15338.075NA37.99537.9137.832NA37.82837.86237.886NA38.01938.07738.112NA37.79237.74837.671NA37.64337.64237.626NA37.80537.94238.096NA37.96537.81937.673NA0.0375410.0374438.695NA39.82839.4939.301NA38.74439.514
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic █▁37.50837.47NA37.38637.3437.303NA37.06637.04937.043NA36.95136.9536.954NA36.86536.85336.85NA36.88936.87636.775NA36.68136.69936.706NA36.85637.01537.121NA36.91936.86836.774NA0.03650.03612836.934NA37.12636.76236.507NA32.94533.733
 us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities mktx:StockOptionsAndRestrictedStock▁█0.028570.061089NA0.0007530.0191010.062964NA0.0056460.2320430.346327NA0.028760.0199840.077732NA0.0107290.0508170.05991NA0.006480.0913080.238224NA0.1301120.1313290.249846NANANANANANANANANANANANANANANANANANANA
us-gaap:EarningsPerShareBasic ▆█▇▇█▇▅▅▅▅▅▄▄▅▃▄▄▄▃▃▃▃▃▂▃▃▂▂▂▂▂▂▂▂▂▂▂▂▁▂▁▁▁▁▁1.792.151.95000000000000021.812.252.011.36000000000000031.461.31.421.23999999999999981.041.11.30.90999999999999970.931.031.150.89999999999999990.840.90.790.67000000000000020.620.660.670.58999999999999990.470.490.470.63000000000000010.490.520.420.56999999999999980.370.350.370.310000000000000050.360.320.30.250.240.19
us-gaap:EarningsPerShareDiluted ▇█▇▇█▇▅▅▅▅▅▄▄▅▃▃▄▄▃▃▃▃▃▂▃▃▂▂▂▂▂▂▂▂▂▂▂▂▁▂▁▁▁▁▁1.772.111.90999999999999931.782.21.961.32000000000000031.421.271.391.21000000000000041.021.071.270.88000000000000030.91.01.110.87999999999999990.820.880.770.64999999999999990.60.640.650.57000000000000010.460.480.460.60999999999999990.480.510.410.540.360.340.350.28999999999999990.340.30.270.23000000000000010.220.18
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:AllocatedShareBasedCompensationExpense ▁█6.1347.424NA6.4515.7916.677NA7.9445.9295.196NA3.953.653.951NA3.5213.5243.943NA3.6993.4433.494NA3.2523.053.042NA2.5292.3352.316NA2.2412.181.9972.2012.1562.0661.9621.8621.8980.8092.29NANANA
us-gaap:ComprehensiveIncomeNetOfTax ▆▇▇▇█▇▅▅▅▅▄▄▄▅▃▃▄▄▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▁▂▁▁▁▁▁▁▁68.42678.52578.8871.32884.32370.46652.80752.65647.46454.09945.4738.08439.25647.87433.39735.25839.31542.12131.08229.82231.35626.91324.23122.60423.90324.60721.67917.35418.04817.27122.98117.84719.26114.93620.18913.08212.42513.16211.35313.44512.24310.432NANANA
us-gaap:GeneralAndAdministrativeExpense ▅▅▄▅▅▅█▆▆▅▅▄▄▄▆▅▄▄▆▆▇▆▅▅▅▄▄▄▃▃▄▃▃▄▃▃▃▃▅▂▂▁▃▂▂3.283.2322.8443.4673.2533.1335.013.7623.83.1243.4262.7442.7082.4753.6053.3642.9012.7093.8463.7314.1623.893.5233.5443.2622.6792.5372.5752.3442.1982.4921.9262.0732.6132.4022.0682.0182.1073.3931.7421.811.0012.1521.8341.85
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest ▆█▇▇█▇▄▅▄▅▄▃▄▄▃▃▃▄▃▃▃▃▂▂▂▂▂▂▂▂▁▁▂▁▁▁86.053101.80190.28987.965104.40391.70261.95767.33862.90965.2256.06647.79753.2161.01349.37147.21749.57355.60750.32746.35450.55144.3736.98635.35337.05938.50233.48928.26829.07127.70824.79926.38831.42224.67122.19121.5NANANANANANANANANA
us-gaap:IncomeTaxExpenseBenefit ▇█▇██▆▅▅▆▅▄▄▅▅▆▅▅▅▇▆▇▆▅▅▅▅▅▄▄▄▄▃▅▄▁▃▄▄▃▄▃▃▃▂▂18.76521.34417.35820.18920.54916.88611.68413.33614.80412.69810.2359.20312.72313.07315.89813.08711.5513.14417.16215.43617.42515.40712.49512.63812.82113.90911.85310.76410.8810.2339.3298.12912.1688.9871.0647.7278.5719.2557.3238.8527.9686.8865.4984.9134.687
us-gaap:InterestExpense ▂▂▁█0.1710.1910.0961.046NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:InterestExpenseDebt us-gaap:CreditFacility us-gaap:RevolvingCreditFacilityNANANA0.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:InterestExpenseDebt us-gaap:FinancialInstrument us-gaap:CollateralizedDebtObligationsNANANA0.1NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:InterestExpenseDebt us-gaap:Range,us-gaap:FinancialInstrument srt:Maximum,us-gaap:CollateralizedDebtObligations▁█0.00.1NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:MarketingAndAdvertisingExpense ▇▂▅▂▄▆▇▅█▅█▆█▄▆▄▆▄▇▄▄▄▄▂▄▂▃▃▄▂▂▂▃▂▂▂▃▃▃▂▂▂▂▁▁3.1281.2042.3071.1481.812.6753.0872.5063.6672.2993.5342.983.5352.0653.0052.0892.7821.8863.1922.141.8241.7781.8881.3041.7641.1921.4291.3311.81.2091.1311.1951.4320.9851.2241.0671.7321.4471.381.281.2480.9741.0090.6790.759
us-gaap:NetIncomeLoss ▆█▇▇█▇▅▅▅▅▅▄▄▅▃▃▄▄▃▃▃▃▃▂▃▃▂▂▂▂▂▂▂▂▂▂▁▂▁▂▁▁▁▁▁67.28880.45772.93167.77683.85474.81650.27354.00248.10552.52245.83138.59440.48747.9433.47334.1338.02342.46333.16530.91833.12628.96324.49122.71524.23824.59321.63617.50418.19117.47523.13318.21319.34315.32620.46513.48212.62913.49311.54313.44411.93710.788.9478.6117.169
us-gaap:NonoperatingIncomeExpense ▂▁▁▄▅▅▆▇███▇▆▆▅▅▅▅-1.124-1.673-1.4080.1580.2680.6131.1061.3732.0322.0312.1011.3851.1760.840.5340.5820.5880.449NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OperatingExpenses ██▆▆▇▆▅▅▅▄▄▃▃▃▃▃▂▃▂▂▂▂▁▁▁▁▁▁▁89.15791.9979.64976.19980.6677.88968.92365.63264.61361.30258.47955.03154.9354.54150.19449.48447.74148.28444.10943.91746.08844.20339.65838.83938.43238.26936.67835.97735.893NANANANANANANANANANANANANANANANA
us-gaap:OperatingIncomeLoss ▆█▆▆█▆▃▃▃▃▂▁▂▃▁▁▁▂87.177103.47491.69787.807104.13591.08960.85165.96560.87763.18953.96546.41252.03460.17348.83746.63548.98555.158NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax ▅▂█▇▄▁▆▃▃▅▃▃▃▄▄▅▅▃▂▃▂▂▄▄▄▄▄▄▄▄▄▃▄▄▄▃▄▄▄▄1.138-1.9325.9514.423-0.351-3.8592.526-1.416-1.11.118-0.476-0.582-1.2880.2680.1751.1021.325-0.365-1.944-1.052-1.804-2.237-0.092-0.105-0.266-0.0490.093-0.111-0.147-0.234-0.196-0.384-0.0730.116-0.112-0.356-0.148-0.132-0.125-0.185NANANANANA
us-gaap:OtherNonoperatingIncomeExpense ▃▁▁█▄▄▄▃▅▆▆▅▅▅▄▄▅▅-1.06-1.589-1.4310.86-0.446-0.656-0.661-0.838-0.0640.0420.175-0.25-0.207-0.328-0.534-0.382-0.252-0.298NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax ▇█▇▇█▇▅▅▅▅▄▄▄▄▄▄▄▄▃▃▄▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁176.334195.464171.346164.006184.795168.978129.774131.597125.49124.491112.444101.443106.964114.71498.5695.58496.314103.89192.24790.27196.63988.57376.64474.19275.49176.77170.16764.24564.96463.39860.44261.13365.55955.55750.38748.25748.82550.73545.13546.56445.79143.60938.60537.41335.326
us-gaap:Revenues ▇█▇▇█▇▅▅▅▅▄▄▄▄▄▄▄▄▄▃▄▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁176.334195.464171.346164.006184.795168.978129.774131.597125.49124.491112.444101.443106.964114.71499.56596.70197.314103.89194.43690.27196.63988.57376.64474.19275.49176.77170.16764.24564.96463.39860.44261.13365.55955.55750.38748.25748.82550.73545.13546.56445.79143.60938.60537.41335.326
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:Assets ██▇▆▅▅▅▄▄▄▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁1537.9231545.8691331.4291245.5041039.217975.603954.93855.026812.009774.809695.539646.131617.598589.273581.232562.347547.041530.714528.042502.151477.115451.842439.041416.322398.946378.694379.884362.909356.719346.373351.578332.688305.378282.881279.841304.928289.728274.51349.458339.2321.267NA299.521NANA
us-gaap:Liabilities ▇█▆▅▃▃▃▃▃▃▂▂▁▁▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁516.063557.636376.368347.965185.733177.72184.839160.403150.101143.66387.66167.51360.2252.10966.46451.43945.81348.35960.02950.45140.96441.42648.32842.85139.08934.02445.67636.60633.7428.11241.21646.06834.81430.3837.12432.99427.99325.59337.01933.36728.41NA34.73NANA
us-gaap:LiabilitiesAndStockholdersEquity ██▇▆▅▅▅▄▄▄▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁1537.9231545.8691331.4291245.5041039.217975.603954.93855.026812.009774.809695.539646.131617.598589.273581.232562.347547.041530.714528.042502.151477.115451.842439.041416.322398.946378.694379.884362.909356.719346.373351.578332.688305.378282.881279.841304.928289.728274.51349.458339.2321.267NA299.521NANA
us-gaap:StockholdersEquity ██▇▇▆▆▆▅▅▄▄▄▄▄▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▂▂▁1021.86988.233955.061897.539853.484797.883770.091694.623661.908631.146607.878578.618557.378537.164514.768510.908501.228482.355468.013451.7436.151410.416390.713373.471359.857344.67334.208326.303322.979318.261310.362286.62270.564252.501242.717271.934261.735248.917312.439305.833292.857NA234.476NANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:CashAndCashEquivalentsAtCarryingValue ▇▇█▅▇▆▄▅▅▄▄▃▂▂▂▂▁▂▂▂▂▂▃▂▂▂▂▂▁▁▁▁▂▁▁▂▁▁▂▂▂▁▁▁▁413.612390.915460.858310.368404.148363.811270.124320.527286.179260.953246.322210.085170.686156.169167.014138.992128.143137.655168.243161.444153.275137.995199.728160.376169.263161.048168.924155.1133.154130.045132.691119.009135.468125.919128.908150.101129.595119.809169.62157.622135.768116.567124.994108.745113.526
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents ▅▆█▁545.243552.682608.05437.301NANA274.253NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:PropertyPlantAndEquipmentGross NANA248.759NANANA206.981NANANA183.639NANANA140.012NANANA106.283NANANA100.878NANANA88.674NANANA76.818NANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType mktx:ComputerHardwareAndRelatedSoftwareNANA52.696NANANA48.379NANANA42.705NANANA35.945NANANA20.152NANANA26.328NANANA24.095NANANA22.051NANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:FurnitureAndFixturesNANA7.078NANANA5.0NANANA5.385NANANA2.347NANANA2.001NANANA1.955NANANA1.921NANANA1.777NANANA1.479NANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:LeaseholdImprovementsNANA29.064NANANA27.966NANANA32.527NANANA11.016NANANA8.351NANANA8.457NANANA8.128NANANA8.129NANANA4.709NANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:OfficeEquipmentNANA8.782NANANA5.725NANANA5.909NANANA4.575NANANA4.228NANANA3.414NANANA2.785NANANA2.38NANANA2.125NANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:SoftwareAndSoftwareDevelopmentCostsNANA151.139NANANA119.911NANANA97.113NANANA86.129NANANA71.551NANANA60.724NANANA50.327NANANA41.062NANANA30.482NANANANANANANANANANA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment NANA163.555NANANA135.186NANANA120.629NANANA101.464NANANA75.179NANANA69.981NANANA56.489NANANA44.115NANANA37.087NANANA30.47NANANA31.264NANA
us-gaap:AmortizationOfIntangibleAssets █▇▅▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▂▂▂▂▂▂▂▂▂▂▁▂▂▁▂▁▂▂3.42.71.90.70.60.70.50.10.10.10.10.10.10.10.10.10.10.10.10.10.10.40.60.60.50.60.60.60.50.60.70.30.80.40.30.40.30.40.4NANANANANANA
us-gaap:PropertyPlantAndEquipmentNet ██▇▇▇▆▆▆▅▅▅▅▄▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▂▂▁▁▁▁▁▁▁▁93.10888.65585.20482.07478.46174.92671.79566.53164.20661.04763.0154.3250.08839.62338.54835.32134.64333.88831.10430.77331.49532.09430.89731.02731.2931.1932.18532.834.39633.39332.70327.61726.44318.74318.00918.46614.9614.87514.4614.07613.409NA12.545NANA
us-gaap:Goodwill █▁▁▁▁▁▁154.789147.388147.388147.388147.394147.394146.861NANANA59.713NANANANANANANANANANANANANANANANANANANANANANANA31.831.831.831.831.8NANANA31.8NANA
us-gaap:IntangibleAssetsNetExcludingGoodwill █▅▅▁▁▁▁119.98990.94595.35458.87359.55260.28560.986NANANA2.962NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:FiniteLivedIntangibleAssetsNet █▆▇▄▄▄▅▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▂▂▁▁▁▁▁119.98990.94595.35458.87359.55260.28560.9862.6752.7712.8662.9623.0593.1553.253.3463.4433.5393.6353.7313.8263.9224.0184.4314.9995.5686.1386.7077.2767.8468.4158.9849.64611.30712.0431.351.6952.052.4052.76NANANA4.228NANA
 us-gaap:IntangibleAssetsNetIncludingGoodwill us-gaap:FairValueByAssetClass us-gaap:IndefinitelivedIntangibleAssets█▇▇▇▇▇▇▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁154.8147.4147.4147.4147.4147.4146.86159.759.759.759.759.759.759.759.759.759.759.759.759.759.759.759.759.759.759.759.759.759.7NA59.7NANANANANANANANANANANANANANA
us-gaap:OperatingLeaseRightOfUseAsset ▁▂▃▄▅▆█▂▄▅73.90675.22375.92476.69277.93379.65181.39975.3976.72278.19NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo █▄▅▁10.62610.45110.51610.328NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree ██▂▁11.1611.12210.2710.083NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour ██▄▁11.15211.12710.93710.75NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive NANA10.937NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive NANA79.003NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:StockholdersEquity ██▇▇▆▆▆▅▅▄▄▄▄▄▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▂▂▁1021.86988.233955.061897.539853.484797.883770.091694.623661.908631.146607.878578.618557.378537.164514.768510.908501.228482.355468.013451.7436.151410.416390.713373.471359.857344.67334.208326.303322.979318.261310.362286.62270.564252.501242.717271.934261.735248.917312.439305.833292.857NA234.476NANA
us-gaap:CommonStockValue ███▁▁▁▁▁▁0.1230.1230.1230.1220.1220.1220.1220.1220.122NA0.122NANANANANANANANANANANANANANANANANA0.1190.1190.119NANANANANANANANANANANANANANA
us-gaap:AdditionalPaidInCapitalCommonStock ▅▅▇▆▇▇███▇█▇▇▆▇████▇▇▆▆▆▅▅▄▄▄▃▃▃▃▂▂▂▁▁█▇▇313.683309.988329.742327.646327.97328.055342.541343.543341.446335.425341.86336.079331.056327.669331.081342.113343.085339.191342.311337.261333.279324.95321.215317.617313.586309.316307.059302.32298.661295.617295.557289.911286.816283.161283.609277.744275.061270.59340.716335.084332.121NA340.615NANA
us-gaap:RetainedEarningsAccumulatedDeficit ██▇▇▇▆▆▅▅▅▅▄▄▄▄▄▄▃▃▃▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁896.977854.747799.369749.211704.219643.129591.086560.164525.43496.562463.252433.227410.419385.725353.583332.506310.777285.15255.14231.743210.606187.228168.011150.975135.721118.943101.81386.15874.6562.47151.04232.79419.4674.977-5.64426.63217.2568.708-0.584-8.68-18.692NA-34.605NANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▆▅▆▃▁▁▃▂▃▃▂▂▃▃▃▃▃▂▂▃▄▅▆▆▆▆▆▆▇▇▇▇▇▇▇▇█████-5.444-6.582-4.65-10.599-14.151-14.62-10.27-12.804-11.458-10.817-12.394-12.033-11.523-10.292-10.226-10.15-11.278-12.57-12.228-10.145-9.049-7.279-5.229-4.969-4.859-4.523-4.537-4.58-4.43-4.287-4.083-3.931-3.565-3.483-3.093-2.817-2.417-2.213-1.882-1.692-1.693NA-1.651NANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:ConsolidatedEntities srt:ParentCompanyNANA-4.65NANANA-10.27NANANA-12.394NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:TreasuryStockValue ▇▇▇▇▇▇▆████▇▇▇▇▆▆▅▅▄▄▄▄▄▄▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁183.479170.043169.523168.841164.676158.803153.388196.402193.632190.146184.962178.776172.695166.059159.791153.682141.477129.537117.33107.27998.80594.60493.40590.27284.71179.18670.24757.71546.02135.65932.27332.27332.27332.27332.27329.74328.28328.28325.93318.99818.998NA70.0NANA
us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue ▁█6.1347.424NA6.4515.7916.677NA7.9445.9295.1964.2993.953.653.9513.4323.5213.5253.9433.8753.6993.4433.4943.2433.2512.9833.0422.592.5282.3352.3162.462.2412.1811.9972.2012.1562.0661.9621.8621.898NANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:NetCashProvidedByUsedInOperatingActivities ▅▂█▁▅▅▄▄▄▃▄▄▄▃▃▄96.726-23.159227.62-48.353104.853120.36989.14167.69269.73339.36970.10567.99454.37931.43946.45252.465NANA65.77352.64328.714-57.38343.85835.74330.56110.034NANANA10.14723.5537.0819.9710.27928.31227.37512.52113.37418.68727.38218.3431.06622.56319.026NA
us-gaap:NetCashProvidedByUsedInInvestingActivities ▄▄▄█▄▆▁▅▄▅▄▅▄▄▅▄-31.014-12.332-34.25290.188-11.62624.557-106.761-4.554-21.29810.562-13.312-7.572-16.683-12.72914.254-13.57NANA-29.281-25.887-4.3516.3395.562-32.58-9.887-1.048NANANA-0.449-8.547-48.195-6.835-5.5441.231-1.214-0.87915.8920.215-2.7772.648-8.662-0.019-0.984NA
us-gaap:NetCashProvidedByUsedInFinancingActivities ▁█▇▆▆▄▆▇█▆███▇▆▇-73.915-18.85-27.741-33.376-34.173-49.822-32.041-27.527-22.305-36.227-20.242-20.551-22.435-29.445-32.733-28.88NANA-27.915-17.792-8.902-10.685-10.11-12.12-11.583-17.241NANANA-11.916-1.691-3.997-3.459-7.927-50.595-5.115-1.747-78.718-6.678-2.437-1.648-0.436-5.938-22.766NA
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect ▂▁█▃▅▆▁▄▃▃▄▄▃▂-7.439-55.368170.74912.56858.73691.744-47.38934.32925.20814.64736.23739.39914.517-10.845NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:DeferredIncomeTaxExpenseBenefit ▄▄▄▆▅▅▅▂▃▅▂▂▃▅█▂▃▄▂▂▆█▂▂▃▄▂▂▃▅▃▂▃▅▁▃▃▅▄▇█▆▇▆1.0090.5911.4563.8762.0042.7632.58-1.542-0.3742.01-1.401-1.276-0.5612.076.26-1.086-0.4481.825-0.994-1.4463.2585.905-1.174-1.673-0.1071.719-1.949-0.9710.3872.1590.332-1.593-0.5022.764-2.601-0.661-0.0042.6231.6334.7195.7474.034.7853.749NA
us-gaap:IncreaseDecreaseInAccountsReceivable ▃▅▃▁▄█▂▄▃▅▃▃▃▆▂▅▃▄▃▃▅▅▂▄▄▅▃▃▄▄▃▃▄▄▃▃▄▃▄▃▄▄▃▄-0.4467.88-2.217-17.2255.81731.64-12.5176.596-4.5713.453-4.4430.21-5.60514.955-10.1827.866-1.4446.113-6.01-6.23810.33112.346-8.8472.3980.90812.289-3.148-4.4431.8454.919-3.056-2.6576.2911.136-2.260.1680.262-2.7775.433-2.4584.3724.318-1.4253.313NA
us-gaap:NetCashProvidedByUsedInOperatingActivities ▅▂█▁▅▅▄▄▄▃▄▄▄▃▃▄96.726-23.159227.62-48.353104.853120.36989.14167.69269.73339.36970.10567.99454.37931.43946.45252.465NANA65.77352.64328.714-57.38343.85835.74330.56110.034NANANA10.14723.5537.0819.9710.27928.31227.37512.52113.37418.68727.38218.3431.06622.56319.026NA
us-gaap:NetIncomeLoss ▆█▇▇█▇▅▅▅▅▅▄▄▅▃▃▄▄▃▃▃▃▃▂▃▃▂▂▂▂▂▂▂▂▂▂▁▂▁▂▁▁▁▁▁67.28880.45772.93167.77683.85474.81650.27354.00248.10552.52245.83138.59440.48747.9433.47334.1338.02342.46333.16530.91833.12628.96324.49122.71524.23824.59321.63617.50418.19117.47523.13318.21319.34315.32620.46513.48212.62913.49311.54313.44411.93710.788.9478.6117.169
us-gaap:ShareBasedCompensation ▆▇▇▇▆▇▆█▆▅▄▄▄▄▄▄▄▄▄▄▄▄▃▃▃▃▃▃▂▂▃▂▂▂▂▂▂▂▂▂▁▂▃▂6.1347.4246.6946.4515.7916.6776.2257.9445.9295.1964.2993.953.653.9513.4323.5213.5253.9433.8753.6993.4433.4943.2433.2512.9833.0422.592.5292.3352.3162.462.2412.181.9972.2012.1562.0661.9621.8621.8980.8092.292.3412.128NA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:NetCashProvidedByUsedInInvestingActivities ▄▄▄█▄▆▁▅▄▅▄▅▄▄▅▄-31.014-12.332-34.25290.188-11.62624.557-106.761-4.554-21.29810.562-13.312-7.572-16.683-12.72914.254-13.57NANA-29.281-25.887-4.3516.3395.562-32.58-9.887-1.048NANANA-0.449-8.547-48.195-6.835-5.5441.231-1.214-0.87915.8920.215-2.7772.648-8.662-0.019-0.984NA
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▄▃▂▃▃▃▃▂▄▁▇▅█▂▃▂▂▃▂▁▂▂▁▂▂▁▁▁▂▂▄▂▄▁▁▃▁▁▁▁▁▁▁▁5.5524.2571.9883.7584.9734.2913.6092.5695.4650.64912.0677.78613.7572.2784.8411.4681.6284.1491.6310.851.2522.6521.0651.3851.5280.8170.6250.2482.1321.6225.981.9416.6220.7940.1983.9110.4370.6070.6431.0011.0180.4980.5210.86NA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
us-gaap:NetCashProvidedByUsedInFinancingActivities ▁█▇▆▆▄▆▇█▆███▇▆▇-73.915-18.85-27.741-33.376-34.173-49.822-32.041-27.527-22.305-36.227-20.242-20.551-22.435-29.445-32.733-28.88NANA-27.915-17.792-8.902-10.685-10.11-12.12-11.583-17.241NANANA-11.916-1.691-3.997-3.459-7.927-50.595-5.115-1.747-78.718-6.678-2.437-1.648-0.436-5.938-22.766NA
us-gaap:PaymentsForRepurchaseOfCommonStock █▁▁▃▄▄▄▂▃▄▄▄▄▄▄▇▇▇▆▅▃▁▂▄▄▆█▇▆▃13.4360.520.6824.1655.8735.4155.8162.773.4865.1846.1866.0816.6366.2686.10912.20511.9412.20710.0518.4744.2011.1993.1335.5615.5258.93912.53211.69410.3623.386NANANANA2.531.46NANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302018-12-312014-06-302014-03-312013-12-31
Value123000.0123000.0123000.0122000.0122000.0122000.0122000.0122000.0122000.0122000.0119000.0119000.0119000.0
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStockValue us-gaap:ConsolidatedEntities

srt:ParentCompany


Common
Period End2020-12-312019-12-312018-12-31
Value123000.0122000.0122000.0
Percentage of CommonStockValue100.0100.0100.0
Percentage of Assets0.00.00.0
Percentage of Assets srt:ParentCompany0.00.00.0

Common Stock Shares Outstanding

us-gaap:CommonStockSharesOutstanding us-gaap:StatementClassOfStock

us-gaap:CommonStockSharesOutstanding

mktx:VotingCommonStock


Common
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value38373737373739393837
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value38383838383737373737373838383737373737373737383737370.0375410.03744383939393839
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value37373737373737373636363636363636363636363637373636360.03650.036128363736363233
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

mktx:StockOptionsAndRestrictedStock


Antidilutive
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value28570.061089.0753.019101.062964.05646.0232040.0346330.028760.019984.077732.010729.050817.059910.06480.091308.0238220.0130110.0131330.0249850.0
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value1.792.151.951.812.252.011.361.461.31.421.241.041.11.30.910.931.031.150.90.840.90.790.670.620.660.670.590.470.490.470.630.490.520.420.570.370.350.370.310.360.320.30.250.240.19
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareDiluted


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value1.772.111.911.782.21.961.321.421.271.391.211.021.071.270.880.91.01.110.880.820.880.770.650.60.640.650.570.460.480.460.610.480.510.410.540.360.340.350.290.340.30.270.230.220.18
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Allocated Share Based Compensation Expense

us-gaap:AllocatedShareBasedCompensationExpense

us-gaap:AllocatedShareBasedCompensationExpense


Allocated
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value6.1347.4246.4515.7916.6777.9445.9295.1963.953.653.9513.5213.5243.9433.6993.4433.4943.2523.053.0422.5292.3352.3162.2412.181.9972.2012.1562.0661.9621.8621.8980.8092.29
Percentage of AllocatedShareBasedCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.53.83.93.14.06.04.74.23.93.43.43.73.73.84.13.63.94.44.04.03.93.63.73.73.33.60.04.54.23.90.04.11.85.3

us-gaap:AllocatedShareBasedCompensationExpense us-gaap:TitleOfIndividual

mktx:EmployeeCompensationPlan


Allocated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value5.927.1036.3666.1335.5126.3995.9477.7065.6454.9164.0133.6543.3933.6923.1753.283.2923.6993.6393.3873.2993.2763.0222.9582.92.8062.3662.2312.1832.0892.1912.0582.0741.8461.9661.9681.967
Percentage of AllocatedShareBasedCompensationExpense96.595.70.095.195.295.80.097.095.294.60.092.593.093.40.093.293.493.80.091.695.893.80.091.095.192.20.088.293.590.20.091.895.192.489.391.395.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.43.60.03.73.03.80.05.94.53.90.03.63.23.20.03.43.43.60.03.83.43.70.04.03.83.70.03.53.43.30.03.43.23.30.04.14.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:EmployeeCompensationPlan0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mktx:NonEmployeeDirectorCompensationPlan


Allocated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value0.2140.321240.3180.2790.278240.2380.2840.28150.2960.2570.259130.2410.2320.244130.3120.1440.218110.2940.150.2369.0930.2980.1520.2278.4380.1830.1060.151
Percentage of AllocatedShareBasedCompensationExpense3.54.30.04.94.84.20.03.04.85.40.07.57.06.60.06.86.66.20.08.44.26.20.09.04.97.80.011.86.59.80.08.24.97.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.00.20.20.20.00.20.20.20.00.30.20.20.00.30.20.20.00.30.10.20.00.40.20.30.00.50.20.40.00.30.20.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:NonEmployeeDirectorCompensationPlan0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value687878718470525247544538394733353942312931262422232421171817221719142013121311131210
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.840.20.043.545.641.70.040.037.843.50.037.536.741.70.036.940.840.50.033.032.430.40.030.531.732.10.027.027.827.20.029.229.426.90.027.125.425.90.028.926.723.9

General And Administrative Expense

us-gaap:GeneralAndAdministrativeExpense

us-gaap:GeneralAndAdministrativeExpense


General
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value3.283.2322.8443.4673.2533.1335.013.7623.83.1243.4262.7442.7082.4753.6053.3642.9012.7093.8463.7314.1623.893.5233.5443.2622.6792.5372.5752.3442.1982.4921.9262.0732.6132.4022.0682.0182.1073.3931.7421.811.0012.1521.8341.85
Percentage of GeneralAndAdministrativeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.91.70.02.11.81.90.02.93.02.50.02.72.52.20.03.53.02.60.04.14.34.40.04.84.33.50.04.03.63.50.03.23.24.70.04.34.14.20.03.74.02.30.04.95.2

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

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value86101908710491616762655647536149474955504650443635373833282927242631242221
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax48.852.10.053.656.554.30.051.250.152.40.047.149.753.20.049.451.553.50.051.352.350.10.047.749.150.20.044.044.743.70.043.247.944.40.044.6

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxExpenseBenefit


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value18211720201611131412109.2031213151311131715171512121213111010109.3298.129128.9871.0647.7278.5719.2557.3238.8527.9686.8865.4984.9134.687
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.610.90.012.311.110.00.010.111.810.20.09.111.911.40.013.712.012.70.017.118.017.40.017.017.018.10.016.816.716.10.013.318.616.20.016.017.618.20.019.017.415.80.013.113.3

Interest Expense

us-gaap:InterestExpense

us-gaap:InterestExpense


Interest
Period End2021-06-302021-03-312020-12-312020-09-30
Value171000.0191000.096000.01046000.0
Percentage of InterestExpense100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.00.6

Interest Expense Debt

us-gaap:InterestExpenseDebt us-gaap:CreditFacility

us-gaap:InterestExpenseDebt

us-gaap:RevolvingCreditFacility


Interest
Period End2020-09-30
Value800000.0
Percentage of InterestExpenseDebt100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RevolvingCreditFacility0.0

us-gaap:InterestExpenseDebt us-gaap:FinancialInstrument

us-gaap:CollateralizedDebtObligations


Interest
Period End2020-09-30
Value100000.0
Percentage of InterestExpenseDebt12.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CollateralizedDebtObligations0.0

us-gaap:InterestExpenseDebt us-gaap:Range, us-gaap:FinancialInstrument

srt:Maximum, us-gaap:CollateralizedDebtObligations


Interest
Period End2021-06-302021-03-31
Value0100000.0
Percentage of InterestExpenseDebt0.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:Maximum us-gaap:CollateralizedDebtObligations0.00.0

Marketing And Advertising Expense

us-gaap:MarketingAndAdvertisingExpense

us-gaap:MarketingAndAdvertisingExpense


Marketing
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value3.1281.2042.3071.1481.812.6753.0872.5063.6672.2993.5342.983.5352.0653.0052.0892.7821.8863.1922.141.8241.7781.8881.3041.7641.1921.4291.3311.81.2091.1311.1951.4320.9851.2241.0671.7321.4471.381.281.2480.9741.0090.6790.759
Percentage of MarketingAndAdvertisingExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.80.60.00.71.01.60.01.92.91.80.02.93.31.80.02.22.91.80.02.41.92.00.01.82.31.60.02.12.81.90.02.02.21.80.02.23.52.90.02.72.72.20.01.82.1

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value6780726783745054485245384047333438423330332824222424211718172318191520131213111311108.9478.6117.169
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.241.20.041.345.444.30.041.038.342.20.038.037.941.80.035.739.540.90.034.334.332.70.030.632.132.00.027.228.027.60.029.829.527.60.027.925.926.60.028.926.124.70.023.020.3

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value6780678374544852453840473334384233303328242224242117181723181915201312131113
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.241.241.345.444.341.038.342.20.038.037.941.80.035.739.540.90.034.334.332.70.030.632.132.00.027.228.027.60.029.829.527.60.027.925.926.60.028.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Nonoperating Income Expense

us-gaap:NonoperatingIncomeExpense

us-gaap:NonoperatingIncomeExpense


Nonoperating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-1124000.0-1673000.0-1408000.0158000.0268000.0613000.01106000.01373000.02032000.02031000.02101000.01385000.01176000.0840000.0534000.0582000.0588000.0449000.0
Percentage of NonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.6-0.90.00.10.10.40.01.01.61.60.01.41.10.70.00.60.60.4

Operating Expenses

us-gaap:OperatingExpenses

us-gaap:OperatingExpenses


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30
Value8991797680776865646158555454504947484443464439383838363535
Percentage of OperatingExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax50.647.10.046.543.646.10.049.951.549.20.054.251.447.50.051.849.646.50.048.747.749.90.052.350.949.80.056.055.3

Operating Income Loss

us-gaap:OperatingIncomeLoss

us-gaap:OperatingIncomeLoss


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value87103918710491606560635346526048464855
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax49.452.90.053.556.453.90.050.148.550.80.045.848.652.50.048.850.953.1

Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value1138000.0-1932000.05951000.04423000.0-351000.0-3859000.02526000.0-1416000.0-1100000.01118000.0-476000.0-582000.0-1288000.0268000.0175000.01102000.01325000.0-365000.0-1944000.0-1052000.0-1804000.0-2237000.0-92000.0-105000.0-266000.0-49000.093000.0-111000.0-147000.0-234000.0-196000.0-384000.0-73000.0116000.0-112000.0-356000.0-148000.0-132000.0-125000.0-185000.0
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.6-1.00.02.7-0.2-2.30.0-1.1-0.90.90.0-0.6-1.20.20.01.21.4-0.40.0-1.2-1.9-2.50.0-0.1-0.4-0.10.0-0.2-0.2-0.40.0-0.6-0.10.20.0-0.7-0.3-0.30.0-0.4

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value1138000.0-1932000.04423000.0-351000.0-3859000.0-1416000.0-1100000.01118000.0-476000.0-582000.0-1288000.0268000.0175000.01101000.01325000.0-365000.0-1944000.0-1052000.0-1804000.0-2237000.0-92000.0-104000.0-267000.0-49000.093000.0-111000.0-147000.0-234000.0-196000.0-384000.0-73000.0116000.0-112000.0
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.099.9100.0100.0100.0100.0100.0100.0100.099.0100.4100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.6-1.02.7-0.2-2.3-1.1-0.90.90.0-0.6-1.20.20.01.21.4-0.40.0-1.2-1.9-2.50.0-0.1-0.4-0.10.0-0.2-0.2-0.40.0-0.6-0.10.20.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherNonoperatingIncomeExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-1060000.0-1589000.0-1431000.0860000.0-446000.0-656000.0-661000.0-838000.0-64000.042000.0175000.0-250000.0-207000.0-328000.0-534000.0-382000.0-252000.0-298000.0
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.6-0.80.00.5-0.2-0.40.0-0.6-0.10.00.0-0.2-0.2-0.30.0-0.4-0.3-0.3

Revenue From Contract With Customer Excluding Assessed Tax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value176195171164184168129131125124112101106114989596103929096887674757670646463606165555048485045464543383735
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductOrService

mktx:CommissionRevenue


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value1561751551501721551171191141121019096102878687
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax88.790.090.991.893.192.390.291.190.990.690.289.289.989.689.390.390.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax88.790.090.991.893.192.390.291.190.990.690.289.289.989.689.390.390.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:CommissionRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:InformationServices


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value9.8449.1628.7718.5018.4278.6428.5157.6937.1567.3667.0577.1746.937.0666.7936.3316.497
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.64.75.15.24.65.16.65.85.75.96.37.16.56.26.96.66.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.64.75.15.24.65.16.65.85.75.96.37.16.56.26.96.66.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:InformationServices100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:OtherRevenues


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value0.2110.2030.1980.230.2220.2290.2330.2510.2540.2650.2760.2810.3010.30.3250.3050.313
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.20.20.20.20.20.30.30.30.30.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.20.20.20.20.20.30.30.30.30.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:OtherRevenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:PostTradeServices


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value9.848106.5644.6894.0544.1533.9233.7843.9564.13.6753.4753.624.5763.4672.6782.489
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.65.23.82.92.22.53.02.93.23.33.33.43.44.03.52.82.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.65.23.82.92.22.53.02.93.23.33.33.43.44.03.52.82.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:PostTradeServices100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductOrService, us-gaap:TimingOfTransferOfGoodOrService

mktx:InformationServices, us-gaap:TransferredAtPointInTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value0.3320.1170.1980.2740.6080.8360.3680.490.1060.1470.2340.1450.1010.2240.150.0640.21
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.10.20.30.50.30.40.10.10.20.10.10.20.20.10.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.10.20.30.50.30.40.10.10.20.10.10.20.20.10.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:InformationServices us-gaap:TransferredAtPointInTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:InformationServices, us-gaap:TransferredOverTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value9.5129.0458.5738.2277.8197.8068.1477.2037.057.2196.8237.0296.8296.8426.6436.2676.287
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.44.65.05.04.24.66.35.55.65.86.16.96.46.06.76.66.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.44.65.05.04.24.66.35.55.65.86.16.96.46.06.76.66.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:InformationServices us-gaap:TransferredOverTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:PostTradeServices, us-gaap:TransferredAtPointInTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value-0.2320.2410.0610.1320.1060.0030.0650.0090.0070.0130.0320.0120.00.2891.0950.3120.019
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.10.10.00.10.10.00.10.00.00.00.00.00.00.31.10.30.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.10.10.00.10.10.00.10.00.00.00.00.00.00.31.10.30.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:PostTradeServices us-gaap:TransferredAtPointInTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0

mktx:PostTradeServices, us-gaap:TransferredOverTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value9.848106.5034.5573.9484.153.8583.7753.9494.0873.6433.4633.624.2872.3722.3662.47
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.65.13.82.82.12.53.02.93.13.33.23.43.43.72.42.52.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.65.13.82.82.12.53.02.93.13.33.23.43.43.72.42.52.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:PostTradeServices us-gaap:TransferredOverTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:StatementGeographical

country:GB


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value20222221212020161516171414141514121412109.839.2109.6339.1979.7019.658
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.512.013.316.716.316.516.314.615.715.115.515.014.914.815.215.913.814.514.313.413.212.213.113.714.314.915.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.512.013.316.716.316.516.314.615.715.115.515.014.914.815.215.913.814.514.313.413.212.213.113.714.314.915.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:GB100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value1381571411071091041039585909683808187777782756664656660545553
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax84.285.483.882.883.283.083.285.083.984.484.184.784.784.884.583.785.985.085.186.286.487.386.685.985.484.784.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax84.285.483.882.883.283.083.285.083.984.484.184.784.784.884.583.785.985.085.186.286.487.386.685.985.484.784.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:US100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:OtherGeographicArea


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value5.3164.9824.9490.6390.6540.6430.6090.4910.4510.4970.5120.3060.3750.3920.3770.3210.2670.4680.4950.330.2640.3540.2530.2620.1990.2180.164
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.22.72.90.50.50.50.50.40.40.50.40.30.40.40.40.30.30.50.60.40.40.50.30.40.30.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.22.72.90.50.50.50.50.40.40.50.40.30.40.40.40.30.30.50.60.40.40.50.30.40.30.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax mktx:OtherGeographicArea100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:Americas


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value143160158142
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax81.281.986.084.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax81.281.986.084.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:Americas100.0100.0100.0100.0

srt:Asia


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value4.7785.8013.8643.922
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.73.02.12.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.73.02.12.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:Asia100.0100.0100.0100.0

srt:Europe


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value28292222
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.115.112.013.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.115.112.013.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:Europe100.0100.0100.0100.0

Revenues

us-gaap:Revenues

us-gaap:Revenues


Revenues
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value176195171164184168129131125124112101106114999697103949096887674757670646463606165555048485045464543383735
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0101.0101.2101.0100.0102.4100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value15371545133112451039975954855812774695646617589581562547530528502477451439416398378379362356346351332305282279304289274349339321299
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:ConsolidatedEntities

srt:ParentCompany


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-31
Value1057869636
Percentage of Assets79.591.191.5
Percentage of Assets79.591.191.5
Percentage of Assets srt:ParentCompany100.0100.0100.0

Liabilities

us-gaap:Liabilities

us-gaap:Liabilities


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value5165573763471851771841601501438767605266514548605040414842393445363328414634303732272537332834
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets33.636.128.327.917.918.219.418.818.518.512.610.49.88.811.49.18.49.111.410.08.69.211.010.39.89.012.010.19.58.111.713.811.410.713.310.89.79.310.69.88.811.6

us-gaap:Liabilities us-gaap:ConsolidatedEntities

srt:ParentCompany


Liabilitiesus-gaap:
Period End2020-12-312019-12-312018-12-31
Value1029928
Percentage of Liabilities27.353.932.9
Percentage of Assets7.710.44.2
Percentage of Assets srt:ParentCompany9.711.54.5

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value15371545133112451039975954855812774695646617589581562547530528502477451439416398378379362356346351332305282279304289274349339321299
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilitiesAndStockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Liabilities
Period End2020-12-312019-12-312018-12-31
Value1057869636
Percentage of LiabilitiesAndStockholdersEquity79.591.191.5
Percentage of Assets79.591.191.5
Percentage of Assets srt:ParentCompany100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value1021988955897853797770694661631607578557537514510501482468451436410390373359344334326322318310286270252242271261248312305292234216194
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets66.463.971.772.182.181.880.681.281.581.587.489.690.291.288.690.991.690.988.690.091.490.889.089.790.291.088.089.990.591.988.386.288.689.386.789.290.390.789.490.291.278.30.00.0

us-gaap:StockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Stockholders
Period End2020-12-312019-12-312018-12-31
Value955770607
Percentage of StockholdersEquity100.0100.0100.0
Percentage of Assets71.780.687.4
Percentage of Assets srt:ParentCompany90.388.595.5

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value-5.444-6.582-4.65-10.599-14.151-14.62-10.27-12.804-11.458-10.817-12.394-12.033-11.523-10.292-10.226-10.15-11.278-12.57-12.228-10.145-9.049-7.279-5.229-4.969-4.859-4.523-4.537-4.58-4.43-4.287-4.083-3.931-3.565-3.483-3.093-2.817-2.417-2.213-1.882-1.692-1.693-1.651-1.391-1.32
Percentage of StockholdersEquity-0.5-0.7-0.5-1.2-1.7-1.8-1.3-1.8-1.7-1.7-2.0-2.1-2.1-1.9-2.0-2.0-2.3-2.6-2.6-2.2-2.1-1.8-1.3-1.3-1.4-1.3-1.4-1.4-1.4-1.3-1.3-1.4-1.3-1.4-1.3-1.0-0.9-0.9-0.6-0.6-0.6-0.7-0.6-0.7
Percentage of Assets-0.4-0.4-0.3-0.9-1.4-1.5-1.1-1.5-1.4-1.4-1.8-1.9-1.9-1.7-1.8-1.8-2.1-2.4-2.3-2.0-1.9-1.6-1.2-1.2-1.2-1.2-1.2-1.3-1.2-1.2-1.2-1.2-1.2-1.2-1.1-0.9-0.8-0.8-0.5-0.5-0.5-0.60.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value313309329327327328342343341335341336331327331342343339342337333324321317313309307302298295295289286283283277275270340335332340313305
Percentage of StockholdersEquity30.731.434.536.538.441.144.549.551.653.156.258.159.461.064.367.068.470.373.174.776.479.282.285.087.189.791.992.792.592.995.2101.1106.0112.1116.8102.1105.1108.7109.1109.6113.4145.3145.0157.1
Percentage of Assets20.420.124.826.331.633.635.940.242.043.349.252.053.655.657.060.862.763.964.867.269.971.973.276.378.681.780.883.383.785.384.187.193.9100.1101.391.194.998.697.598.8103.4113.70.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312012-03-312011-12-312011-06-302010-12-312009-12-312008-12-31
Value0.1230.1230.1230.1220.1220.1220.1220.1220.1220.1220.1220.1210.1210.1210.1210.1210.1210.1210.120.120.120.1210.1210.120.120.120.120.120.1190.1190.1190.1180.1150.1130.110.1080.1040.102
Percentage of StockholdersEquity0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.1
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value8968547997497046435915605254964634334103853533323102852552312101871681501351181018674625132194.977-5.64426178.708-0.584-8.68-18.692-34.605-55.403-68.855
Percentage of StockholdersEquity87.886.583.783.582.580.676.880.679.478.776.274.973.671.868.765.162.059.154.551.348.345.643.040.437.734.530.526.423.119.616.411.47.22.0-2.39.86.63.5-0.2-2.8-6.4-14.8-25.6-35.4
Percentage of Assets58.355.360.060.267.865.961.965.564.764.166.667.066.565.560.859.156.853.748.346.244.141.438.336.334.031.426.823.720.918.014.59.96.41.8-2.08.76.03.2-0.2-2.6-5.8-11.60.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value-183.479-170.043-169.523-168.841-164.676-158.803-153.388-196.402-193.632-190.146-184.962-178.776-172.695-166.059-159.791-153.682-141.477-129.537-117.33-107.279-98.805-94.604-93.405-90.272-84.711-79.186-70.247-57.715-46.021-35.659-32.273-32.273-32.273-32.273-32.273-29.743-28.283-28.283-25.933-18.998-18.998-70.0-40.0-40.0
Percentage of StockholdersEquity-18.0-17.2-17.7-18.8-19.3-19.9-19.9-28.3-29.3-30.1-30.4-30.9-31.0-30.9-31.0-30.1-28.2-26.9-25.1-23.8-22.7-23.1-23.9-24.2-23.5-23.0-21.0-17.7-14.2-11.2-10.4-11.3-11.9-12.8-13.3-10.9-10.8-11.4-8.3-6.2-6.5-29.9-18.5-20.6
Percentage of Assets-11.9-11.0-12.7-13.6-15.8-16.3-16.1-23.0-23.8-24.5-26.6-27.7-28.0-28.2-27.5-27.3-25.9-24.4-22.2-21.4-20.7-20.9-21.3-21.7-21.2-20.9-18.5-15.9-12.9-10.3-9.2-9.7-10.6-11.4-11.5-9.8-9.8-10.3-7.4-5.6-5.9-23.40.00.0
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashAndCashEquivalentsAtCarryingValue


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value413390460310404363270320286260246210170156167138128137168161153137199160169161168155133130132119135125128150129119169157135116124108113103107
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets26.925.334.624.938.937.328.337.535.233.735.432.527.626.528.724.723.425.931.932.232.130.545.538.542.442.544.542.737.337.537.735.844.444.546.149.244.743.648.546.542.30.041.70.00.00.00.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:BalanceSheetLocation

us-gaap:CashAndCashEquivalents


Cash
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value413390460310270
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0
Percentage of Assets26.925.334.624.928.3
Percentage of Assets us-gaap:CashAndCashEquivalents0.00.00.00.00.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:ConsolidatedEntities

srt:ParentCompany


Cash
Period End2020-12-312019-12-312018-12-31
Value554895
Percentage of CashAndCashEquivalentsAtCarryingValue12.117.938.9
Percentage of Assets4.25.113.8
Percentage of Assets srt:ParentCompany5.35.515.1

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Cash
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value545552608437274
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0
Percentage of Assets35.535.845.735.128.7

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:PropertyPlantAndEquipmentGross


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value2482061831401061008876
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets18.721.726.424.120.123.023.321.8

us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType

mktx:ComputerHardwareAndRelatedSoftware


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value5248423520262422
Percentage of PropertyPlantAndEquipmentGross21.223.423.325.719.026.127.228.7
Percentage of Assets4.05.16.16.23.86.06.36.3
Percentage of Assets mktx:ComputerHardwareAndRelatedSoftware0.00.00.00.00.00.00.00.0

us-gaap:FurnitureAndFixtures


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value7.0785.05.3852.3472.0011.9551.9211.7771.479
Percentage of PropertyPlantAndEquipmentGross2.82.42.91.71.91.92.22.30.0
Percentage of Assets0.50.50.80.40.40.40.50.50.5
Percentage of Assets us-gaap:FurnitureAndFixtures0.00.00.00.00.00.00.00.00.0

us-gaap:LeaseholdImprovements


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value292732118.3518.4578.1288.1294.709
Percentage of PropertyPlantAndEquipmentGross11.713.517.77.97.98.49.210.60.0
Percentage of Assets2.22.94.71.91.61.92.12.31.7
Percentage of Assets us-gaap:LeaseholdImprovements0.00.00.00.00.00.00.00.00.0

us-gaap:OfficeEquipment


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value8.7825.7255.9094.5754.2283.4142.7852.382.125
Percentage of PropertyPlantAndEquipmentGross3.52.83.23.34.03.43.13.10.0
Percentage of Assets0.70.60.80.80.80.80.70.70.8
Percentage of Assets us-gaap:OfficeEquipment0.00.00.00.00.00.00.00.00.0

us-gaap:SoftwareAndSoftwareDevelopmentCosts


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value15111997867160504130
Percentage of PropertyPlantAndEquipmentGross60.857.952.961.567.360.256.853.50.0
Percentage of Assets11.412.614.014.813.613.813.211.710.9
Percentage of Assets us-gaap:SoftwareAndSoftwareDevelopmentCosts0.00.00.00.00.00.00.00.00.0

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value16313512010175695644373031
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets12.314.217.317.514.215.914.912.513.38.710.4

Amortization Of Intangible Assets

us-gaap:AmortizationOfIntangibleAssets

us-gaap:AmortizationOfIntangibleAssets


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value3400000.02700000.01900000.0700000.0600000.0700000.0500000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0400000.0600000.0600000.0500000.0600000.0600000.0600000.0500000.0600000.0700000.0300000.0800000.0400000.0300000.0400000.0300000.0400000.0400000.0
Percentage of AmortizationOfIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:PropertyPlantAndEquipmentNet


Property
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value938885827874716664616354503938353433313031323031313132323433322726181818141414141312
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.15.76.46.67.67.77.57.87.97.99.18.48.16.76.66.36.36.45.96.16.67.17.07.57.88.28.59.09.69.69.38.38.76.66.46.15.25.44.14.14.24.2

us-gaap:PropertyPlantAndEquipmentNet us-gaap:ConsolidatedEntities

srt:ParentCompany


Property
Period End2020-12-312019-12-312018-12-31
Value232525
Percentage of PropertyPlantAndEquipmentNet27.635.240.9
Percentage of Assets1.82.63.7
Percentage of Assets srt:ParentCompany2.22.94.0

us-gaap:PropertyPlantAndEquipmentNet us-gaap:StatementGeographical

country:GB


Property
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value1614129.417.3557.057.5087.7878.5649.09710109.78.9317.8547.7138.0778.1768.8768.919.149.4188.9029.0578.305
Percentage of PropertyPlantAndEquipmentNet20.318.516.513.111.111.012.312.415.818.226.327.327.525.823.224.826.226.027.728.829.530.128.528.125.4
Percentage of Assets1.31.41.31.00.90.91.01.11.31.51.81.81.71.61.51.51.61.72.02.02.22.42.42.42.4
Percentage of Assets country:GB0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

country:US


Property
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value65636262595753554540292725252623222323212121222324
Percentage of PropertyPlantAndEquipmentNet79.681.583.586.988.989.087.787.684.281.873.672.672.574.276.875.173.774.072.371.170.569.871.471.874.6
Percentage of Assets5.26.26.46.56.97.06.97.97.16.65.04.84.64.74.94.44.54.95.15.05.35.55.96.16.9
Percentage of Assets country:US0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mktx:OtherGeographicArea


Property
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value0.0170.0190.0220.0290.030.0350.0210.0230.0220.0230.0250.0260.0190.0180.020.0210.0220.0230.0220.0190.0190.0240.0230.0290.017
Percentage of PropertyPlantAndEquipmentNet0.00.00.00.00.00.10.00.00.00.00.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets mktx:OtherGeographicArea0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

srt:Americas


Property
Period End2021-06-302021-03-312020-12-312019-12-31
Value74706862
Percentage of PropertyPlantAndEquipmentNet79.579.980.686.9
Percentage of Assets4.84.65.26.5
Percentage of Assets srt:Americas0.00.00.00.0

srt:Asia


Property
Period End2021-06-302021-03-312020-12-312019-12-31
Value0.0070.0050.0060.009
Percentage of PropertyPlantAndEquipmentNet0.00.00.00.0
Percentage of Assets0.00.00.00.0
Percentage of Assets srt:Asia0.00.00.00.0

srt:Europe


Property
Period End2021-06-302021-03-312020-12-312019-12-31
Value1917169.41
Percentage of PropertyPlantAndEquipmentNet20.520.119.413.1
Percentage of Assets1.21.21.21.0
Percentage of Assets srt:Europe0.00.00.00.0

Goodwill

us-gaap:Goodwill

us-gaap:Goodwill


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value15414714714714714714659313131313131
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets10.19.511.111.814.215.115.48.611.410.411.011.69.110.6

us-gaap:Goodwill us-gaap:BusinessAcquisition

mktx:LiquidityEdgeLLC


Goodwillus-gaap:
Period End2020-09-302020-06-302020-03-312019-11-01
Value87878787
Percentage of Goodwill59.559.559.50.0
Percentage of Assets7.08.49.00.0
Percentage of Assets mktx:LiquidityEdgeLLC0.00.00.00.0

mktx:MuniBrokersLimitedLiabilityCompany


Goodwillus-gaap:
Period End2021-04-09
Value7.4
Percentage of Goodwill0.0
Percentage of Assets0.0
Percentage of Assets mktx:MuniBrokersLimitedLiabilityCompany0.0

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill


Intangible
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value1199095585960602.962
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.85.97.24.75.76.26.40.4

us-gaap:IntangibleAssetsNetExcludingGoodwill us-gaap:ConsolidatedEntities

srt:ParentCompany


Intangible
Period End2020-12-312019-12-31
Value0.0270.03
Percentage of IntangibleAssetsNetExcludingGoodwill0.00.0
Percentage of Assets0.00.0
Percentage of Assets srt:ParentCompany0.00.0

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet

us-gaap:FiniteLivedIntangibleAssetsNet


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value1199095585960602.6752.7712.8662.9623.0593.1553.253.3463.4433.5393.6353.7313.8263.9224.0184.4314.9995.5686.1386.7077.2767.8468.4158.9849.64611121.351.6952.052.4052.764.228
Percentage of FiniteLivedIntangibleAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.85.97.24.75.76.26.40.30.30.40.40.50.50.60.60.60.60.70.70.80.80.91.01.21.41.61.82.02.22.42.62.93.74.30.50.60.70.90.81.4

us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass

mktx:TechnologyAndOtherIntangibles


Finite
Period End2021-06-302021-03-312020-12-31
Value4.5780.0270.027
Percentage of FiniteLivedIntangibleAssetsNet3.80.00.0
Percentage of Assets0.30.00.0
Percentage of Assets mktx:TechnologyAndOtherIntangibles0.00.00.0

mktx:TradenamesAndPatents


Finite
Period End2020-12-312019-12-31
Value0.0270.105
Percentage of FiniteLivedIntangibleAssetsNet0.00.2
Percentage of Assets0.00.0
Percentage of Assets mktx:TradenamesAndPatents0.00.0

us-gaap:CustomerRelationships


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value1159095585960602.6752.7712.8662.9623.0593.1553.253.3463.4433.5393.6353.7313.8263.9224.0184.1154.214.3064.4024.4994.5944.694.7864.8825.0596.2346.4861.1661.2581.3491.441.5311.946
Percentage of FiniteLivedIntangibleAssetsNet96.2100.0100.0100.0100.099.999.8100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.092.984.277.371.767.163.159.856.954.352.455.153.986.474.265.859.955.546.0
Percentage of Assets7.55.97.24.75.76.26.40.30.30.40.40.50.50.60.60.60.60.70.70.80.80.90.91.01.11.21.21.31.31.41.41.52.02.30.40.40.50.50.40.6
Percentage of Assets us-gaap:CustomerRelationships0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TradeNames


Finite
Period End2020-09-302020-06-302020-03-312019-12-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value0.0280.0290.0820.1050.0170.0420.0670.0920.1170.1420.1670.1920.2170.2420.2670.2920.020.0450.0710.0970.1230.227
Percentage of FiniteLivedIntangibleAssetsNet0.00.00.10.20.40.81.21.51.72.02.12.32.42.52.42.41.52.73.54.04.55.4
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.10.10.10.10.10.00.00.00.00.00.1
Percentage of Assets us-gaap:TradeNames0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Intangible Assets Net Including Goodwill

us-gaap:IntangibleAssetsNetIncludingGoodwill us-gaap:FairValueByAssetClass

us-gaap:IntangibleAssetsNetIncludingGoodwill

us-gaap:IndefinitelivedIntangibleAssets


Intangible
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value1541471471471471471465959595959595959595959595959595959595959595959
Percentage of IntangibleAssetsNetIncludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets10.19.511.111.814.215.115.47.07.47.78.69.29.710.110.310.610.911.211.311.912.513.213.614.315.015.815.716.516.717.0
Percentage of Assets us-gaap:IndefinitelivedIntangibleAssets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OperatingLeaseRightOfUseAsset


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value73757576777981757678
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.84.95.76.27.58.28.58.89.410.1

us-gaap:OperatingLeaseRightOfUseAsset us-gaap:ConsolidatedEntities

srt:ParentCompany


Operating
Period End2020-12-312019-12-31
Value6468
Percentage of OperatingLeaseRightOfUseAsset84.984.2
Percentage of Assets4.87.2
Percentage of Assets srt:ParentCompany6.17.9

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo


Lessee
Period End2021-06-302021-03-312020-12-312020-09-30
Value10101010
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0100.0100.0100.0
Percentage of Assets0.70.70.80.8

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree


Lessee
Period End2021-06-302021-03-312020-12-312020-09-30
Value11111010
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0100.0100.0100.0
Percentage of Assets0.70.70.80.8

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour


Lessee
Period End2021-06-302021-03-312020-12-312020-09-30
Value11111010
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0100.0100.0100.0
Percentage of Assets0.70.70.80.9

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive


Lessee
Period End2020-12-31
Value10
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0
Percentage of Assets0.8

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive


Lessee
Period End2020-12-31
Value79
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0
Percentage of Assets5.9

Operating Lease Liability

us-gaap:OperatingLeaseLiability

us-gaap:OperatingLeaseLiability


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value91929393949697928990
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.96.07.07.59.19.910.310.811.011.7

us-gaap:OperatingLeaseLiability us-gaap:ConsolidatedEntities

srt:ParentCompany


Operating
Period End2020-12-312019-12-31
Value7983
Percentage of OperatingLeaseLiability85.385.6
Percentage of Assets6.08.8
Percentage of Assets srt:ParentCompany7.59.6

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue


Lessee
Period End2021-06-302021-03-312020-12-312020-09-30
Value128131133135
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0100.0100.0100.0
Percentage of Assets8.48.510.010.8

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount


Lessee
Period End2021-06-302021-03-312020-12-312020-09-30
Value37384041
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount100.0100.0100.0100.0
Percentage of Assets2.42.53.03.3

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value1021988955897853797770694661631607578557537514510501482468451436410390373359344334326322318310286270252242271261248312305292234216194
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets66.463.971.772.182.181.880.681.281.581.587.489.690.291.288.690.991.690.988.690.091.490.889.089.790.291.088.089.990.591.988.386.288.689.386.789.290.390.789.490.291.278.30.00.0

us-gaap:StockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Stockholders
Period End2020-12-312019-12-312018-12-31
Value955770607
Percentage of StockholdersEquity100.0100.0100.0
Percentage of Assets71.780.687.4
Percentage of Assets srt:ParentCompany90.388.595.5

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value-5.444-6.582-4.65-10.599-14.151-14.62-10.27-12.804-11.458-10.817-12.394-12.033-11.523-10.292-10.226-10.15-11.278-12.57-12.228-10.145-9.049-7.279-5.229-4.969-4.859-4.523-4.537-4.58-4.43-4.287-4.083-3.931-3.565-3.483-3.093-2.817-2.417-2.213-1.882-1.692-1.693-1.651-1.391-1.32
Percentage of StockholdersEquity-0.5-0.7-0.5-1.2-1.7-1.8-1.3-1.8-1.7-1.7-2.0-2.1-2.1-1.9-2.0-2.0-2.3-2.6-2.6-2.2-2.1-1.8-1.3-1.3-1.4-1.3-1.4-1.4-1.4-1.3-1.3-1.4-1.3-1.4-1.3-1.0-0.9-0.9-0.6-0.6-0.6-0.7-0.6-0.7
Percentage of Assets-0.4-0.4-0.3-0.9-1.4-1.5-1.1-1.5-1.4-1.4-1.8-1.9-1.9-1.7-1.8-1.8-2.1-2.4-2.3-2.0-1.9-1.6-1.2-1.2-1.2-1.2-1.2-1.3-1.2-1.2-1.2-1.2-1.2-1.2-1.1-0.9-0.8-0.8-0.5-0.5-0.5-0.60.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value313309329327327328342343341335341336331327331342343339342337333324321317313309307302298295295289286283283277275270340335332340313305
Percentage of StockholdersEquity30.731.434.536.538.441.144.549.551.653.156.258.159.461.064.367.068.470.373.174.776.479.282.285.087.189.791.992.792.592.995.2101.1106.0112.1116.8102.1105.1108.7109.1109.6113.4145.3145.0157.1
Percentage of Assets20.420.124.826.331.633.635.940.242.043.349.252.053.655.657.060.862.763.964.867.269.971.973.276.378.681.780.883.383.785.384.187.193.9100.1101.391.194.998.697.598.8103.4113.70.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312012-03-312011-12-312011-06-302010-12-312009-12-312008-12-31
Value0.1230.1230.1230.1220.1220.1220.1220.1220.1220.1220.1220.1210.1210.1210.1210.1210.1210.1210.120.120.120.1210.1210.120.120.120.120.120.1190.1190.1190.1180.1150.1130.110.1080.1040.102
Percentage of StockholdersEquity0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.1
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value8968547997497046435915605254964634334103853533323102852552312101871681501351181018674625132194.977-5.64426178.708-0.584-8.68-18.692-34.605-55.403-68.855
Percentage of StockholdersEquity87.886.583.783.582.580.676.880.679.478.776.274.973.671.868.765.162.059.154.551.348.345.643.040.437.734.530.526.423.119.616.411.47.22.0-2.39.86.63.5-0.2-2.8-6.4-14.8-25.6-35.4
Percentage of Assets58.355.360.060.267.865.961.965.564.764.166.667.066.565.560.859.156.853.748.346.244.141.438.336.334.031.426.823.720.918.014.59.96.41.8-2.08.76.03.2-0.2-2.6-5.8-11.60.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value-183.479-170.043-169.523-168.841-164.676-158.803-153.388-196.402-193.632-190.146-184.962-178.776-172.695-166.059-159.791-153.682-141.477-129.537-117.33-107.279-98.805-94.604-93.405-90.272-84.711-79.186-70.247-57.715-46.021-35.659-32.273-32.273-32.273-32.273-32.273-29.743-28.283-28.283-25.933-18.998-18.998-70.0-40.0-40.0
Percentage of StockholdersEquity-18.0-17.2-17.7-18.8-19.3-19.9-19.9-28.3-29.3-30.1-30.4-30.9-31.0-30.9-31.0-30.1-28.2-26.9-25.1-23.8-22.7-23.1-23.9-24.2-23.5-23.0-21.0-17.7-14.2-11.2-10.4-11.3-11.9-12.8-13.3-10.9-10.8-11.4-8.3-6.2-6.5-29.9-18.5-20.6
Percentage of Assets-11.9-11.0-12.7-13.6-15.8-16.3-16.1-23.0-23.8-24.5-26.6-27.7-28.0-28.2-27.5-27.3-25.9-24.4-22.2-21.4-20.7-20.9-21.3-21.7-21.2-20.9-18.5-15.9-12.9-10.3-9.2-9.7-10.6-11.4-11.5-9.8-9.8-10.3-7.4-5.6-5.9-23.40.00.0
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302018-12-312014-06-302014-03-312013-12-31
Value123000.0123000.0123000.0122000.0122000.0122000.0122000.0122000.0122000.0122000.0119000.0119000.0119000.0
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStockValue us-gaap:ConsolidatedEntities

srt:ParentCompany


Common
Period End2020-12-312019-12-312018-12-31
Value123000.0122000.0122000.0
Percentage of CommonStockValue100.0100.0100.0
Percentage of Assets0.00.00.0
Percentage of Assets srt:ParentCompany0.00.00.0

Additional Paid In Capital Common Stock

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:AdditionalPaidInCapitalCommonStock


Additional
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value313309329327327328342343341335341336331327331342343339342337333324321317313309307302298295295289286283283277275270340335332340
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets20.420.124.826.331.633.635.940.242.043.349.252.053.655.657.060.862.763.964.867.269.971.973.276.378.681.780.883.383.785.384.187.193.9100.1101.391.194.998.697.598.8103.4113.7

us-gaap:AdditionalPaidInCapitalCommonStock us-gaap:ConsolidatedEntities

srt:ParentCompany


Additional
Period End2020-12-312019-12-312018-12-31
Value329342341
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0
Percentage of Assets24.835.949.2
Percentage of Assets srt:ParentCompany31.239.453.7

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value8968547997497046435915605254964634334103853533323102852552312101871681501351181018674625132194.977-5.64426178.708-0.584-8.68-18.692-34.605
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets58.355.360.060.267.865.961.965.564.764.166.667.066.565.560.859.156.853.748.346.244.141.438.336.334.031.426.823.720.918.014.59.96.41.8-2.08.76.03.2-0.2-2.6-5.8-11.6

us-gaap:RetainedEarningsAccumulatedDeficit us-gaap:ConsolidatedEntities

srt:ParentCompany


Retained
Period End2020-12-312019-12-312018-12-31
Value799591463
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0
Percentage of Assets60.061.966.6
Percentage of Assets srt:ParentCompany75.668.072.8

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value-5444000.0-6582000.0-4650000.0-10599000.0-14151000.0-14620000.0-10270000.0-12804000.0-11458000.0-10817000.0-12394000.0-12033000.0-11523000.0-10292000.0-10226000.0-10150000.0-11278000.0-12570000.0-12228000.0-10145000.0-9049000.0-7279000.0-5229000.0-4969000.0-4859000.0-4523000.0-4537000.0-4580000.0-4430000.0-4287000.0-4083000.0-3931000.0-3565000.0-3483000.0-3093000.0-2817000.0-2417000.0-2213000.0-1882000.0-1692000.0-1693000.0-1651000.0
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.4-0.4-0.3-0.9-1.4-1.5-1.1-1.5-1.4-1.4-1.8-1.9-1.9-1.7-1.8-1.8-2.1-2.4-2.3-2.0-1.9-1.6-1.2-1.2-1.2-1.2-1.2-1.3-1.2-1.2-1.2-1.2-1.2-1.2-1.1-0.9-0.8-0.8-0.5-0.5-0.5-0.6

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:ConsolidatedEntities

srt:ParentCompany


Accumulated
Period End2020-12-312019-12-312018-12-31
Value-4650000.0-10270000.0-12394000.0
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0
Percentage of Assets-0.3-1.1-1.8
Percentage of Assets srt:ParentCompany-0.4-1.2-1.9

Treasury Stock Value

us-gaap:TreasuryStockValue

us-gaap:TreasuryStockValue


Treasury
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value18317016916816415815319619319018417817216615915314112911710798949390847970574635323232323229282825181870
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets11.911.012.713.615.816.316.123.023.824.526.627.728.028.227.527.325.924.422.221.420.720.921.321.721.220.918.515.912.910.39.29.710.611.411.59.89.810.37.45.65.923.4

us-gaap:TreasuryStockValue us-gaap:ConsolidatedEntities

srt:ParentCompany


Treasury
Period End2020-12-312019-12-312018-12-31
Value169153184
Percentage of TreasuryStockValue100.0100.0100.0
Percentage of Assets12.716.126.6
Percentage of Assets srt:ParentCompany16.017.629.0

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

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value6.1347.4246.4515.7916.6777.9445.9295.1964.2993.953.653.9513.4323.5213.5253.9433.8753.6993.4433.4943.2433.2512.9833.0422.592.5282.3352.3162.462.2412.1811.9972.2012.1562.0661.9621.8621.898
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value6.1347.4246.4515.7916.6777.9445.9295.1964.2993.953.653.9513.4323.5213.5253.9433.8753.6993.4433.4943.2433.2512.9833.0422.592.5282.3352.3162.462.2412.1811.9972.2012.1562.0661.9621.8621.898
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value96-23.159227-48.35310412089676939706754314652655228-57.383433530101023371910282712131827181.0662219
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax54.9-11.8132.8-29.556.771.268.751.455.631.662.367.050.827.447.154.971.358.329.7-64.857.248.240.513.116.039.060.730.518.556.256.725.626.441.458.840.12.458.450.9

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-31.014-12.332-34.25290-11.62624-106.761-4.554-21.29810-13.312-7.572-16.683-12.72914-13.57-29.281-25.887-4.3516.3395.562-32.58-9.887-1.048-0.449-8.547-48.195-6.835-5.5441.231-1.214-0.879150.215-2.7772.648-8.662-0.019-0.984
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-17.6-6.3-20.055.0-6.314.5-82.3-3.5-17.08.5-11.8-7.5-15.6-11.114.5-14.2-31.7-28.7-4.57.27.3-43.9-13.1-1.4-0.7-14.1-78.8-10.4-10.02.4-2.5-1.831.30.5-6.05.8-19.9-0.0-2.6

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-73915000.0-18850000.0-27741000.0-33376000.0-34173000.0-49822000.0-32041000.0-27527000.0-22305000.0-36227000.0-20242000.0-20551000.0-22435000.0-29445000.0-32733000.0-28880000.0-27915000.0-17792000.0-8902000.0-10685000.0-10110000.0-12120000.0-11583000.0-17241000.0-11916000.0-1691000.0-3997000.0-3459000.0-7927000.0-50595000.0-5115000.0-1747000.0-78718000.0-6678000.0-2437000.0-1648000.0-436000.0-5938000.0-22766000.0
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-41.9-9.6-16.2-20.4-18.5-29.5-24.7-20.9-17.8-29.1-18.0-20.3-21.0-25.7-33.2-30.2-30.3-19.7-9.2-12.1-13.2-16.3-15.3-22.5-18.8-2.8-6.5-5.3-14.3-100.4-10.6-3.6-155.2-14.8-5.2-3.6-1.0-15.4-60.9

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

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-7.439-55.368170125891-47.389342514363914-10.845
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-4.2-28.399.77.731.854.3-36.526.120.111.832.238.813.6-9.5

Deferred Income Tax Expense Benefit

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:DeferredIncomeTaxExpenseBenefit


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value1.0090.5911.4563.8762.0042.7632.58-1.542-0.3742.01-1.401-1.276-0.5612.076.26-1.086-0.4481.825-0.994-1.4463.2585.905-1.174-1.673-0.1071.719-1.949-0.9710.3872.1590.332-1.593-0.5022.764-2.601-0.661-0.0042.6231.6334.7195.7474.034.7853.749
Percentage of DeferredIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Increase Decrease In Accounts Receivable

us-gaap:IncreaseDecreaseInAccountsReceivable

us-gaap:IncreaseDecreaseInAccountsReceivable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-0.4467.88-2.217-17.2255.81731-12.5176.596-4.5713-4.4430.21-5.60514-10.1827.866-1.4446.113-6.01-6.2381012-8.8472.3980.90812-3.148-4.4431.8454.919-3.056-2.6576.2911.136-2.260.1680.262-2.7775.433-2.4584.3724.318-1.4253.313
Percentage of IncreaseDecreaseInAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value96-23.159227-48.35310412089676939706754314652655228-57.383433530101023371910282712131827181.0662219
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax54.9-11.8132.8-29.556.771.268.751.455.631.662.367.050.827.447.154.971.358.329.7-64.857.248.240.513.116.039.060.730.518.556.256.725.626.441.458.840.12.458.450.9

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value6780726783745054485245384047333438423330332824222424211718172318191520131213111311108.9478.6117.169
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.241.242.641.345.444.338.741.038.342.240.838.037.941.834.035.739.540.936.034.334.332.732.030.632.132.030.827.228.027.638.329.829.527.640.627.925.926.625.628.926.124.723.223.020.3

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value6780678374544852453840473334384233303328242224242117181723181915201312131113
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.241.241.345.444.341.038.342.240.838.037.941.834.035.739.540.936.034.334.332.732.030.632.132.030.827.228.027.638.329.829.527.640.627.925.926.625.628.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Share Based Compensation

us-gaap:ShareBasedCompensation

us-gaap:ShareBasedCompensation


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value6.1347.4246.6946.4515.7916.6776.2257.9445.9295.1964.2993.953.653.9513.4323.5213.5253.9433.8753.6993.4433.4943.2433.2512.9833.0422.592.5292.3352.3162.462.2412.181.9972.2012.1562.0661.9621.8621.8980.8092.292.3412.128
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-31.014-12.332-34.25290-11.62624-106.761-4.554-21.29810-13.312-7.572-16.683-12.72914-13.57-29.281-25.887-4.3516.3395.562-32.58-9.887-1.048-0.449-8.547-48.195-6.835-5.5441.231-1.214-0.879150.215-2.7772.648-8.662-0.019-0.984
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-17.6-6.3-20.055.0-6.314.5-82.3-3.5-17.08.5-11.8-7.5-15.6-11.114.5-14.2-31.7-28.7-4.57.27.3-43.9-13.1-1.4-0.7-14.1-78.8-10.4-10.02.4-2.5-1.831.30.5-6.05.8-19.9-0.0-2.6

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value5.5524.2571.9883.7584.9734.2913.6092.5695.4650.649127.786132.2784.8411.4681.6284.1491.6310.851.2522.6521.0651.3851.5280.8170.6250.2482.1321.6225.981.9416.6220.7940.1983.9110.4370.6070.6431.0011.0180.4980.5210.86
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-73915000.0-18850000.0-27741000.0-33376000.0-34173000.0-49822000.0-32041000.0-27527000.0-22305000.0-36227000.0-20242000.0-20551000.0-22435000.0-29445000.0-32733000.0-28880000.0-27915000.0-17792000.0-8902000.0-10685000.0-10110000.0-12120000.0-11583000.0-17241000.0-11916000.0-1691000.0-3997000.0-3459000.0-7927000.0-50595000.0-5115000.0-1747000.0-78718000.0-6678000.0-2437000.0-1648000.0-436000.0-5938000.0-22766000.0
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-41.9-9.6-16.2-20.4-18.5-29.5-24.7-20.9-17.8-29.1-18.0-20.3-21.0-25.7-33.2-30.2-30.3-19.7-9.2-12.1-13.2-16.3-15.3-22.5-18.8-2.8-6.5-5.3-14.3-100.4-10.6-3.6-155.2-14.8-5.2-3.6-1.0-15.4-60.9

Payments For Repurchase Of Common Stock

us-gaap:PaymentsForRepurchaseOfCommonStock

us-gaap:PaymentsForRepurchaseOfCommonStock


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312012-12-312012-09-30
Value130.520.6824.1655.8735.4155.8162.773.4865.1846.1866.0816.6366.2686.109121112108.4744.2011.1993.1335.5615.5258.9391211103.3862.531.46
Percentage of PaymentsForRepurchaseOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Effective Income Tax Rate Continuing Operations

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:EffectiveIncomeTaxRateContinuingOperations


Effective
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value21.821.0-0.323.00.1970.184-20.69619.80.2350.195
Percentage of EffectiveIncomeTaxRateContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice


Share
Period 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
Value223.6175.16132.9367.636.823.8313.8115.0113.629.429.099.19.17
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-31
Value110.981
Percentage of DeferredTaxLiabilities100.0100.0

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsNet


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312014-09-302013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value24268.5366.5491415135.25213146.7025.8225.6848.0899.5891419
Percentage of DeferredTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Unrecognized Tax Benefits

us-gaap:UnrecognizedTaxBenefits

us-gaap:UnrecognizedTaxBenefits


Unrecognized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value166.8314.7182.650.0290.2650.2650.2650.0493.6473.3292.9242.685
Percentage of UnrecognizedTaxBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:AdjustmentsRelatedToTaxWithholdingExpenseBenefitForShareBasedCompensation

mktx:AdjustmentsRelatedToTaxWithholdingExpenseBenefitForShareBasedCompensation


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value6.86276.7846.535216.210.2581115-0.0570.3767.621
Percentage of AdjustmentsRelatedToTaxWithholdingExpenseBenefitForShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:AdjustmentsRelatedToTaxWithholdingExpenseBenefitForShareBasedCompensation us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value6.86276.7846.535216.210.2581115-0.0570.3767.621
Percentage of AdjustmentsRelatedToTaxWithholdingExpenseBenefitForShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:AmortizationOfOperatingLeaseRightOfUseAssets

mktx:AmortizationOfOperatingLeaseRightOfUseAssets


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1704000.01664000.01696000.01821000.01680000.01645000.01491000.01469000.01544000.01291000.0
Percentage of AmortizationOfOperatingLeaseRightOfUseAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:ContractWithCustomerLiabilityForeignCurrencyTranslation

mktx:ContractWithCustomerLiabilityForeignCurrencyTranslation


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value-5000.0-10000.0-87000.0-56000.05000.088000.0-59000.027000.023000.0-20000.019000.012000.0
Percentage of ContractWithCustomerLiabilityForeignCurrencyTranslation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:ContractWithCustomerLiabilityForeignCurrencyTranslation us-gaap:ProductOrService

mktx:PostTradeServices


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value-5000.0-10000.0-87000.0-56000.05000.088000.0-59000.027000.023000.0-20000.019000.012000.0
Percentage of ContractWithCustomerLiabilityForeignCurrencyTranslation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:ContractWithCustomerLiabilityPaymentsReceived

mktx:ContractWithCustomerLiabilityPaymentsReceived


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value6.4317.0246.1327.2485.5926.1175.4884.775.1325.6663.6554.845
Percentage of ContractWithCustomerLiabilityPaymentsReceived100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:ContractWithCustomerLiabilityPaymentsReceived us-gaap:ProductOrService

mktx:InformationServices


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value2.6432.4172.1263.1532.2112.1031.4092.02.0731.9571.3851.972
Percentage of ContractWithCustomerLiabilityPaymentsReceived41.134.434.743.539.534.425.741.940.434.537.940.7

mktx:PostTradeServices


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value3.7884.6074.0064.0953.3814.0144.0792.773.0593.7092.272.873
Percentage of ContractWithCustomerLiabilityPaymentsReceived58.965.665.356.560.565.674.358.159.665.562.159.3

mktx:ContractWithCustomerLiabilityRevenueRecognizedIncludingAdditions

mktx:ContractWithCustomerLiabilityRevenueRecognizedIncludingAdditions


Contract
Period End2021-06-302021-03-31
Value6.5666.457
Percentage of ContractWithCustomerLiabilityRevenueRecognizedIncludingAdditions100.0100.0

mktx:ContractWithCustomerLiabilityRevenueRecognizedIncludingAdditions us-gaap:ProductOrService

mktx:InformationServices


Contract
Period End2021-06-302021-03-31
Value2.5132.454
Percentage of ContractWithCustomerLiabilityRevenueRecognizedIncludingAdditions38.338.0

mktx:PostTradeServices


Contract
Period End2021-06-302021-03-31
Value4.0534.003
Percentage of ContractWithCustomerLiabilityRevenueRecognizedIncludingAdditions61.762.0

mktx:DisclosedTrading us-gaap:ProductOrService

mktx:DisclosedTrading

mktx:CommissionRevenue


Disclosed
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value8498838095846469676655495666545459
Percentage of DisclosedTrading100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:DistributionFeesAndUnusedMinimumFees us-gaap:ProductOrService

mktx:DistributionFeesAndUnusedMinimumFees

mktx:CommissionRevenue


Distribution
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value2927272726262523232324242422222016
Percentage of DistributionFeesAndUnusedMinimumFees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:DividendsTreasuryStockCash

mktx:DividendsTreasuryStockCash


Dividends
Period End2020-09-30
Value22
Percentage of DividendsTreasuryStockCash100.0

mktx:DividendsTreasuryStockCash us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Dividends
Period End2020-09-30
Value22
Percentage of DividendsTreasuryStockCash100.0

mktx:IncreaseDecreaseInOperatingLeaseLiabilities

mktx:IncreaseDecreaseInOperatingLeaseLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-1887000.0-1845000.0-1119000.0-1597000.0-1556000.0-1516000.0-1629000.02222000.0-1101000.0-321000.0
Percentage of IncreaseDecreaseInOperatingLeaseLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:OperatingLeaseCostForSubleased us-gaap:IncomeStatementLocation

mktx:OperatingLeaseCostForSubleased

us-gaap:OtherNonoperatingIncomeExpense


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value544000.0497000.0624000.0609000.0635000.0536000.0559000.0707000.0583000.0
Percentage of OperatingLeaseCostForSubleased100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:PaymentsToAcquireBusinessesNetOfCashAndCashEquivalentsAcquired

mktx:PaymentsToAcquireBusinessesNetOfCashAndCashEquivalentsAcquired


Payments
Period End2020-09-30
Value-0.006
Percentage of PaymentsToAcquireBusinessesNetOfCashAndCashEquivalentsAcquired100.0

mktx:TransactionCosts

mktx:TransactionCosts


Transaction
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value4.3724.6944.9974.8385.7135.513.3452.7822.612.5772.2571.762.0121.7251.4771.4761.5171.3271.3061.0351.9531.766
Percentage of TransactionCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:VariableTransactionFees us-gaap:ProductOrService

mktx:VariableTransactionFees

mktx:CommissionRevenue


Variable
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value1271481271231461299195908976657179656570
Percentage of VariableTransactionFees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationConsiderationTransferred1 us-gaap:BalanceSheetLocation, us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationConsiderationTransferred1

mktx:AccountsPayableAccruedExpensesAndOtherLiabilities, mktx:MuniBrokersLimitedLiabilityCompany


Business
Period End2021-04-09
Value39
Percentage of BusinessCombinationConsiderationTransferred1100.0

us-gaap:BusinessCombinationConsiderationTransferred1 us-gaap:BusinessAcquisition

mktx:LiquidityEdgeLLC


Business
Period End2020-09-302020-06-302020-03-312019-11-01
Value0.00.0153152
Percentage of BusinessCombinationConsiderationTransferred10.00.00.00.0

us-gaap:CommunicationsAndInformationTechnology

us-gaap:CommunicationsAndInformationTechnology


Communications
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value10108.9228.4178.5928.1617.1557.3816.4745.7826.4155.8795.7935.7795.6065.0354.8224.5854.4494.2454.2774.3043.723.8913.9674.3384.3854.3594.4494.4924.3374.5094.0993.1913.5343.2623.0152.9552.9162.7722.7242.52.6692.5432.353
Percentage of CommunicationsAndInformationTechnology100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConcentrationRiskPercentage1 us-gaap:StatementGeographical, us-gaap:ConcentrationRiskByBenchmark, us-gaap:ConcentrationRiskByType

us-gaap:ConcentrationRiskPercentage1

country:GB, us-gaap:SalesRevenueNet, us-gaap:GeographicConcentrationRisk


Concentration
Period End2021-03-312020-03-312019-03-312018-03-31
Value10.00.10.10.1
Percentage of ConcentrationRiskPercentage1100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiabilityRevenueRecognized

us-gaap:ContractWithCustomerLiabilityRevenueRecognized


Contract
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value6.285.4695.5785.7794.8224.8444.9514.6114.643
Percentage of ContractWithCustomerLiabilityRevenueRecognized100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiabilityRevenueRecognized us-gaap:ProductOrService

mktx:InformationServices


Contract
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value2.2492.0011.8431.8231.8191.8191.7991.8251.776
Percentage of ContractWithCustomerLiabilityRevenueRecognized35.836.633.031.537.737.636.339.638.3

mktx:PostTradeServices


Contract
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value4.0313.4683.7353.9563.0033.0253.1522.7862.867
Percentage of ContractWithCustomerLiabilityRevenueRecognized64.263.467.068.562.362.463.760.461.7

us-gaap:CurrentFederalTaxExpenseBenefit

us-gaap:CurrentFederalTaxExpenseBenefit


Current
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value5.852126.9964.566107.7662.8289.6289.9486.5248.4986.3588.7927.977.369119.038.3151413107.07810119.7747.3169.4039.288.0234.9946.0676.7429.0893.5085.3286.642-2.5543.5653.5790.026
Percentage of CurrentFederalTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CurrentForeignTaxExpenseBenefit

us-gaap:CurrentForeignTaxExpenseBenefit


Current
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value5.6214.8194.7793.5713.7413.4473.8053.3853.2732.7712.8262.5022.4151.1143.01.1911.4981.5461.5671.7141.751.1351.1571.2341.4340.520.9360.2270.561-0.2670.4120.3120.418-0.1280.5280.908-0.031-0.090.1510.5360.713-0.206
Percentage of CurrentForeignTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CurrentIncomeTaxExpenseBenefit

us-gaap:CurrentIncomeTaxExpenseBenefit


Current
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value1720151618149.104141510111013119.6381411111816149.5021314129.3141211105.9137.728.877114.4596.238.442-2.8834.6453.551.6152.3870.04
Percentage of CurrentIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CurrentStateAndLocalTaxExpenseBenefit

us-gaap:CurrentStateAndLocalTaxExpenseBenefit


Current
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value6.2833.4114.1278.1763.9172.912.4711.8651.9571.3930.3121.6192.0771.919-0.7311.6511.471.4582.0321.8951.8711.2891.9462.0361.721.4782.1491.5831.5871.1861.2411.8231.8191.0790.3740.892-0.2981.17-0.181.0531.6740.246
Percentage of CurrentStateAndLocalTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredFederalIncomeTaxExpenseBenefit

us-gaap:DeferredFederalIncomeTaxExpenseBenefit


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value1.2750.6021.122.9741.4751.9052.384-1.231-0.1761.602-1.095-0.663-0.5050.8466.041-0.93-0.4791.539-1.011-0.9182.8364.977-1.166-1.2460.0643.84-0.396-0.3541.0023.3311.622-0.380.9893.747-3.796-0.2719.4733.5454.7076.4594.9054.46
Percentage of DeferredFederalIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredForeignIncomeTaxExpenseBenefit

us-gaap:DeferredForeignIncomeTaxExpenseBenefit


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value-568000.0-112000.062000.0355000.0263000.0506000.0-203000.0-97000.0-167000.0159000.0-141000.0-477000.045000.01094000.0-506000.02000.0103000.0120000.0-160000.0-374000.016000.0215000.0453000.0-218000.0-177000.0131000.0-257000.0101000.0-367000.0478000.0-126000.0-289000.0-331000.0102000.0-8000.0-52000.0-139000.0193000.0-3000.0-91000.0-492000.0602000.0
Percentage of DeferredForeignIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxesAndTaxCredits

us-gaap:DeferredIncomeTaxesAndTaxCredits


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-30
Value1.0090.5911.4443.9142.0072.7342.609-1.558-0.3912.022-1.42-1.286-0.6132.0616.264-1.073-0.4281.827-1.194-1.694-2.0242.331-0.834-1.673-0.1074.595-0.635-0.3260.7094.321.609-0.7480.889
Percentage of DeferredIncomeTaxesAndTaxCredits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredStateAndLocalIncomeTaxExpenseBenefit

us-gaap:DeferredStateAndLocalIncomeTaxExpenseBenefit


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value302000.0101000.0274000.0547000.0266000.0352000.0399000.0-214000.0-31000.0249000.0-165000.0-136000.0-101000.0130000.0725000.0-158000.0-72000.0166000.0177000.0-154000.0406000.0713000.0-121000.0-209000.06000.0624000.018000.0-73000.074000.0511000.0113000.0-79000.0184000.0679000.0-1362000.0-392000.02120000.0872000.0-931000.0869000.01168000.01784000.0
Percentage of DeferredStateAndLocalIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DepreciationAmortizationAndAccretionNet

us-gaap:DepreciationAmortizationAndAccretionNet


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value1311109.0328.3058.0677.736.76.3456.0825.8486.1735.795.2695.2084.5834.794.6934.2924.3254.544.6814.6854.6424.6034.6124.4254.4824.3514.1213.7463.5593.1772.5692.337
Percentage of DepreciationAmortizationAndAccretionNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DepreciationAndAmortization

us-gaap:DepreciationAndAmortization


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value1311109.0328.3058.0677.736.76.3456.0825.8486.1735.795.2695.2084.5834.794.6934.2924.3254.544.6814.6854.6424.6034.6124.4254.4824.3514.1213.9723.464.5042.5692.3372.0811.9611.8541.7931.7991.6271.5621.5521.561.622
Percentage of DepreciationAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStockCash

us-gaap:DividendsCommonStockCash


Dividends
Period End2021-06-302021-03-312020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value2525222219191915151515121212129.7689.7819.7489.7467.4557.4617.467.4635.9815.9966.0126.0464.8854.8874.8534.705524.1064.0814.2013.4473.432
Percentage of DividendsCommonStockCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStockCash us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value2525222219191915151515121212129.7689.7819.7489.7467.4557.4617.467.4635.9815.9966.0126.0464.8854.8874.8534.705524.1064.0814.2013.4473.432
Percentage of DividendsCommonStockCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations


Effect
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value764000.0-1027000.05122000.04109000.0-318000.0-3360000.02272000.0-1282000.0-922000.0943000.0-314000.0-472000.0-744000.0-110000.0
Percentage of EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense

us-gaap:EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense


Employee
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value5.64.05.95.76.33.50.43.01.70.11.83.85.35.8
Percentage of EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-4.0782.5990.222.326-12.481150.491-1.1232.887-3.7649.76-0.9455.2520.3071.303-2.476-1.5151.074-0.302-0.062-2.0154.723-1.253-0.0050.40.8490.576-5.576-0.6934.743-5.9084.05-1.9214.96-1.1630.207-2.1092.351-0.3190.6920.41-0.605-0.240.515
Percentage of IncreaseDecreaseInAccountsPayableAndAccruedLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInBrokerageReceivables

us-gaap:IncreaseDecreaseInBrokerageReceivables


Increase
Period End2021-06-302021-03-312020-12-31
Value-59.057270-121.152
Percentage of IncreaseDecreaseInBrokerageReceivables100.0100.0100.0

us-gaap:IncreaseDecreaseInContractWithCustomerLiability

us-gaap:IncreaseDecreaseInContractWithCustomerLiability


Increase
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1024000.0118000.0451000.0-232000.0-79000.0265000.0735000.0-975000.0190000.041000.0894000.0
Percentage of IncreaseDecreaseInContractWithCustomerLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInEmployeeRelatedLiabilities

us-gaap:IncreaseDecreaseInEmployeeRelatedLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value11-34.103111117-25.436128.4139.97-22.3547.5857.8568.001-20.8915.4757.9479.208-20.9116.2378.3349.302-18.3866.4586.7297.149-16.356.9265.9986.013-17.6284.6557.2316.903-14.9694.4814.9324.686-13.6083.7533.7415.959-11.8194.245.043
Percentage of IncreaseDecreaseInEmployeeRelatedLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInIncomeTaxes

us-gaap:IncreaseDecreaseInIncomeTaxes


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value-7.9154.8146.0916.2591.8891.953.4660.382-5.9282.2673.720.409-5.4684.3049.047-0.209-10.4347.3664.0641.013-7.8826.0260.368-2.645-2.3743.712.475-2.681-0.8913.4620.689
Percentage of IncreaseDecreaseInIncomeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInPayablesToBrokerDealers

us-gaap:IncreaseDecreaseInPayablesToBrokerDealers


Increase
Period End2021-06-302021-03-312020-12-31
Value-29.965174-4.794
Percentage of IncreaseDecreaseInPayablesToBrokerDealers100.0100.0100.0

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value7706000.0-3082000.02498000.05603000.02415000.0-8539000.08479000.0-3986000.05395000.0-5264000.03888000.0-2427000.03182000.0-852000.02536000.0-4904000.07261000.02146000.0-26000.0-1423000.0574000.03000000.02315000.0-5560000.05366000.0541000.0-2099000.0-2928000.02996000.0-1313000.0157000.0-517000.02282000.0-76000.0-494000.0-5159000.06906000.0-1665000.0-2445000.02141000.03480000.0898000.0393000.0-461000.0
Percentage of IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInTradingSecurities

us-gaap:IncreaseDecreaseInTradingSecurities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value11-5.495-5.3160.638-6.88-56.394-4.4169.225-2.839-6.0155.815-9.9596.342-3.054
Percentage of IncreaseDecreaseInTradingSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInTradingSecurities us-gaap:InvestmentType

mktx:MutualFundsHeldInRabbiTrust


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.3471.6130.8520.461.070.2890.3480.0270.1971.546-0.3840.1140.0421.1610.1090.110.1011.519-0.0010.0440.0311.253
Percentage of IncreaseDecreaseInTradingSecurities3.1-29.4-16.072.1-15.6-0.5-7.90.3-6.9-25.7-6.6-1.10.7-38.00.00.00.00.00.00.00.00.0

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements


Incremental
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value596000.0685000.0-1000.0774000.0813000.0772000.013000.0929000.0861000.0789000.0-10000.0877000.0912000.0932000.0-39000.01154000.01224000.01262000.03000.0903000.0872000.0896000.06000.0962000.0943000.0920000.09000.0949000.0927000.0975000.036000.01046000.0951000.0899000.01298600.01041.01312.01761.02601600.0439.02329.02422.0
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestExpenseShortTermBorrowings us-gaap:ConsolidatedEntities, us-gaap:StatementGeographical

us-gaap:InterestExpenseShortTermBorrowings

srt:Subsidiaries, country:GB


Interest
Period End2021-03-31
Value200000.0
Percentage of InterestExpenseShortTermBorrowings100.0

us-gaap:InvestmentIncomeNonoperating

us-gaap:InvestmentIncomeNonoperating


Investment
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value107000.0107000.0119000.0344000.0714000.01269000.01767000.02211000.02096000.01989000.01926000.01635000.01383000.01168000.01068000.0964000.0840000.0747000.0
Percentage of InvestmentIncomeNonoperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LaborAndRelatedExpense

us-gaap:LaborAndRelatedExpense


Labor
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value404836374141333232322726262824252527222325242121202119181818161715161414151513131516131414
Percentage of LaborAndRelatedExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LeaseCost

us-gaap:LeaseCost


Lease
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value3.3483.3243.1973.4393.3643.4652.8772.6112.6872.869
Percentage of LeaseCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OccupancyNet

us-gaap:OccupancyNet


Occupancy
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value3.33.3173.223.4453.2863.4743.092.8022.7982.9493.8443.5283.4673.3371.5041.7951.4221.4041.0751.221.2251.1611.2151.2461.2320.9921.0631.1271.1021.0892.0011.2051.2870.9320.7640.7320.7570.7590.7260.7210.7080.7660.6460.7060.707
Percentage of OccupancyNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingLeaseCost us-gaap:ProductOrService

us-gaap:OperatingLeaseCost

us-gaap:Occupancy


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value3.3463.3233.2173.4323.3573.4492.8722.6022.6562.745
Percentage of OperatingLeaseCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeForeignCurrencyTranslationGainLossArisingDuringPeriodTax

us-gaap:OtherComprehensiveIncomeForeignCurrencyTranslationGainLossArisingDuringPeriodTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value-133000.0-413000.0-560000.01654000.0121000.02441000.0-2499000.01012000.0721000.0-452000.0544000.0240000.01328000.0-823000.0-221000.0-953000.0-1106000.0-527000.0959000.0346000.02089000.02012000.0-29000.0-69000.0-166000.05000.059000.0-96000.0-91000.0-146000.0-95000.0-242000.0-46000.073000.0-27000.0-179000.0
Percentage of OtherComprehensiveIncomeForeignCurrencyTranslationGainLossArisingDuringPeriodTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax


Other
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value-871000.0820000.0-491000.070000.0459000.0459000.0115000.072000.057000.0-334000.0-251000.027000.0-33000.023000.0-139000.0-44000.034000.0187000.0-168000.0-6000.0-69000.063000.0-50000.0-39000.04000.030000.044000.018000.0-9000.0-506000.0-164000.0-44000.0
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value-871000.0820000.0-491000.070000.0459000.0459000.0115000.072000.057000.0-334000.0-251000.027000.0-33000.023000.0-139000.0-44000.034000.0187000.0-168000.0-6000.0-69000.063000.0-50000.0-39000.04000.030000.044000.0
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value-2000.0-871000.0820000.0-491000.08000.070000.0459000.0459000.0115000.072000.057000.0-334000.0-251000.026000.0-33000.023000.0-139000.0-44000.034000.0187000.0-168000.0-6000.0-69000.063000.0-46000.0-27000.04000.052000.044000.018000.0-9000.0-506000.0-164000.0-44000.0-56000.0-199000.0-65000.0186000.0392000.0-110000.0
Percentage of OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value-155000.00-276000.0259000.0-155000.03000.022000.0144000.0143000.043000.023000.018000.0-107000.0-49000.016000.0-20000.014000.0-85000.0-27000.021000.0115000.0-104000.0-4000.0-43000.039000.0-25000.0-16000.02000.032000.028000.011000.0-5000.0-19000.0-70000.0-40000.0
Percentage of OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherNoncashIncomeExpense

us-gaap:OtherNoncashIncomeExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value102000.074000.01277000.01472000.0-163000.0-2036000.01672000.0-1182000.0-291000.0587000.0-333000.0-991000.0-1200000.0186000.0-663000.0-550000.0-347000.0-393000.0-292000.0-232000.0-317000.0-329000.0-411000.0-437000.0-772000.0-429000.0-243000.0-630000.0-294000.0-558000.0-381000.0-267000.0677000.0267000.0-447000.0
Percentage of OtherNoncashIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsOfOrdinaryDividends

us-gaap:PaymentsOfOrdinaryDividends


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value2425222222231818181915151515121212129.5819.6019.5869.7277.3337.3397.3457.5175.8795.8985.9326.2324.8094.774.8535.405514.1064.0814.2013.4473.4323.4163.3882.5912.658
Percentage of PaymentsOfOrdinaryDividends100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value6.86277.8566.7846.535217.5496.210.258110.103-0.0570.3767.621144.7950.4697.642-0.7560.3440.3555.230.0460.2070.0954.1480.0120.040.0414.9270.00.00.05.0010.00.0145.8180.00.095-0.0974.417
Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.00.00.0100.0100.00.0100.0100.0100.0

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt


Payments
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.00.0238.995112174537610110157
Percentage of PaymentsToAcquireAvailableForSaleSecuritiesDebt0.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireBusinessesGross us-gaap:BalanceSheetLocation, us-gaap:BusinessAcquisition

us-gaap:PaymentsToAcquireBusinessesGross

mktx:AccountsPayableAccruedExpensesAndOtherLiabilities, mktx:MuniBrokersLimitedLiabilityCompany


Payments
Period End2021-04-09
Value17
Percentage of PaymentsToAcquireBusinessesGross100.0

us-gaap:PaymentsToAcquireBusinessesGross us-gaap:BusinessAcquisition

mktx:MuniBrokersLLC


Payments
Period End2020-09-30
Value45
Percentage of PaymentsToAcquireBusinessesGross0.0

mktx:MuniBrokersLimitedLiabilityCompany


Payments
Period End2021-04-09
Value17
Percentage of PaymentsToAcquireBusinessesGross100.0

mktx:RegulatoryServicesGMBHOfDeutscheBorseGroup


Payments
Period End2020-11-30
Value22
Percentage of PaymentsToAcquireBusinessesGross0.0

us-gaap:PaymentsToAcquireBusinessesGross us-gaap:BusinessAcquisition, us-gaap:SubsequentEventType

mktx:MuniBrokersLimitedLiabilityCompany, us-gaap:SubsequentEvent


Payments
Period End2021-04-09
Value17
Percentage of PaymentsToAcquireBusinessesGross99.4

us-gaap:PaymentsToDevelopSoftware

us-gaap:PaymentsToDevelopSoftware


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value8.3848.0759.4948.1216.2256.7788.5456.5534.1263.1842.5342.6352.9463.593.3773.4273.4953.1723.062.9163.1073.0353.0722.7012.1622.6542.7482.4412.42.5712.5392.1221.9181.3661.3341.3151.261.2981.1671.1080.9480.8420.5730.51
Percentage of PaymentsToDevelopSoftware100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PrincipalTransactionsRevenue us-gaap:ProductOrService

us-gaap:PrincipalTransactionsRevenue

mktx:CommissionRevenue


Principal
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value3946424047402526232320161513111111
Percentage of PrincipalTransactionsRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PrincipalTransactionsRevenue us-gaap:ProductOrService, us-gaap:FinancialInstrument

mktx:CommissionRevenue, us-gaap:USTreasurySecurities


Principal
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value2.6373.262.5212.2643.0244.563
Percentage of PrincipalTransactionsRevenue6.67.06.05.66.411.3

us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities

us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities


Proceeds
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value0.010223451425636777103101514144544614128.012109.724.813104.0388.1261.663.751.8255.5052.4152.772.854.043.4617.9626.574105.5424.3319.88526
Percentage of ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleAndMaturityOfMarketableSecurities

us-gaap:ProceedsFromSaleAndMaturityOfMarketableSecurities


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value135.59.4000000000000310733111236275100101123117674953605621181613109.74.810
Percentage of ProceedsFromSaleAndMaturityOfMarketableSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromShortTermDebt

us-gaap:ProceedsFromShortTermDebt


Proceeds
Period End2021-06-302021-03-312020-12-31
Value1.04669100
Percentage of ProceedsFromShortTermDebt100.0100.0100.0

us-gaap:ProceedsFromStockOptionsExercised

us-gaap:ProceedsFromStockOptionsExercised


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value4421000.0244000.03259000.09000.0659000.080000.0322000.0363000.0350000.0172000.01586000.01016000.0113000.0258000.0332000.0302000.0838000.0500000.0127000.034000.01307000.0831000.0294000.0540000.0298000.0692000.01121000.0545000.0426000.0419000.01223000.0436000.0750000.0630000.02528000.0569000.05074000.0354000.01944000.0-1380000.01635000.04608000.0
Percentage of ProceedsFromStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProfessionalFees

us-gaap:ProfessionalFees


Professional
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value109.64108.2698.0655.6756.3897.0186.2965.8315.3535.6855.4265.0575.4555.5474.0864.2794.7264.3424.2453.8623.543.213.0113.2823.4633.5143.4263.9724.9424.544.7264.6014.0183.2022.8373.0242.3542.2472.6652.8722.1342.2411.99
Percentage of ProfessionalFees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RepaymentsOfSubordinatedDebt

us-gaap:RepaymentsOfSubordinatedDebt


Repayments
Period End2021-06-302021-03-312020-12-31
Value3435100
Percentage of RepaymentsOfSubordinatedDebt100.0100.0100.0

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability


Right
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value330000.0878000.022000.017000.014000.0674000.07042000.0
Percentage of RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue us-gaap:TitleOfIndividual, us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue

mktx:EmployeeCompensationPlan, us-gaap:PerformanceShares


Share
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-30
Value0523.000360.90
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue0.0100.00.00.0100.00.0

mktx:EmployeeCompensationPlan, us-gaap:RestrictedStock


Share
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-30
Value1.24526.51.989.29367.229.45
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue0.0100.70.00.0101.80.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue us-gaap:TitleOfIndividual, us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue

mktx:EmployeeCompensationPlan, us-gaap:PerformanceShares


Share
Period End2021-06-302021-03-312019-09-30
Value0138.510
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue0.0100.00.0

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value4421000.0244000.09000.0659000.080000.0363000.0350000.0172000.01586000.01016000.0113000.0258000.0332000.0302000.0838000.0500000.0127000.034000.01307000.0831000.0294000.0540000.0298000.0692000.01121000.0545000.0426000.0419000.01223000.0436000.0750000.0630000.02528000.0569000.05102000.0326000.01943000.0-1474000.0
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value4421000.0244000.09000.0659000.080000.0363000.0350000.0172000.01585000.01016000.0113000.0258000.0332000.0302000.0838000.0499000.0127000.034000.01307000.0831000.0293000.0540000.0298000.0692000.01121000.0544000.0426000.0419000.01223000.0436000.0750000.0629000.02528000.0569000.05099000.0326000.01941000.0-1474000.0
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.099.9100.0100.0100.0100.0100.0100.099.8100.0100.0100.0100.099.7100.0100.0100.0100.099.8100.0100.0100.0100.0100.099.8100.0100.099.9100.099.9100.0

us-gaap:StockRepurchasedAndRetiredDuringPeriodValue

us-gaap:StockRepurchasedAndRetiredDuringPeriodValue


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312012-12-312012-09-302012-06-302012-03-31
Value130.524.1655.8735.4152.773.4865.1846.1866.0816.6366.2686.109121112108.4744.2011.1993.1335.5615.5258.9391211103.3862.531.460.02771
Percentage of StockRepurchasedAndRetiredDuringPeriodValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockRepurchasedAndRetiredDuringPeriodValue us-gaap:StatementEquityComponents

us-gaap:TreasuryStock


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312012-12-312012-09-302012-06-302012-03-31
Value130.524.1655.8735.4152.773.4865.1846.1866.0816.6366.2686.109121112108.4744.2011.1993.1335.5615.5258.9391211103.3862.531.460.018
Percentage of StockRepurchasedAndRetiredDuringPeriodValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.025.6

us-gaap:SubleaseIncome us-gaap:IncomeStatementLocation

us-gaap:SubleaseIncome

us-gaap:OtherNonoperatingIncomeExpense


Sublease
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value544000.0502000.0644000.0605000.0635000.0536000.0559000.0707000.0583000.0
Percentage of SubleaseIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TreasuryStockValueAcquiredCostMethod us-gaap:ShareRepurchaseProgram

us-gaap:TreasuryStockValueAcquiredCostMethod

mktx:ShareRepurchaseProgram


Treasury
Period End2021-06-302021-03-31
Value130.5
Percentage of TreasuryStockValueAcquiredCostMethod100.0100.0

us-gaap:UnrecognizedTaxBenefitsPeriodIncreaseDecrease

us-gaap:UnrecognizedTaxBenefitsPeriodIncreaseDecrease


Unrecognized
Period End2020-09-30
Value4800000.0
Percentage of UnrecognizedTaxBenefitsPeriodIncreaseDecrease100.0

us-gaap:VariableLeaseCost us-gaap:ProductOrService

us-gaap:VariableLeaseCost

us-gaap:Occupancy


Variable
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value2000.06000.003000.07000.016000.05000.09000.031000.0124000.0
Percentage of VariableLeaseCost100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

mktx:DeferredTaxAssetsOperatingLeaseLiabilities

mktx:DeferredTaxAssetsOperatingLeaseLiabilities


Deferred
Period End2020-12-312019-12-31
Value1920
Percentage of DeferredTaxAssetsOperatingLeaseLiabilities100.0100.0

mktx:DeferredTaxLiabilitiesDepreciationAndAmortization

mktx:DeferredTaxLiabilitiesDepreciationAndAmortization


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value9729000.04085000.01847000.01369000.01456000.01953000.02461000.01905000.02025000.01905000.0
Percentage of DeferredTaxLiabilitiesDepreciationAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:DeferredTaxLiabilitiesOperatingLeaseRightOfUseAssets

mktx:DeferredTaxLiabilitiesOperatingLeaseRightOfUseAssets


Deferred
Period End2020-12-312019-12-31
Value1516
Percentage of DeferredTaxLiabilitiesOperatingLeaseRightOfUseAssets100.0100.0

mktx:InvestmentsInSubsidiaries us-gaap:ConsolidatedEntities

mktx:InvestmentsInSubsidiaries

srt:ParentCompany


Investments
Period End2020-12-312019-12-312018-12-31
Value853570356
Percentage of InvestmentsInSubsidiaries100.0100.0100.0

mktx:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFiveAndThereafter

mktx:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFiveAndThereafter


Lessee
Period End2021-06-302021-03-312020-09-30
Value797989
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFiveAndThereafter100.0100.0100.0

mktx:MarketableSecuritiesAccumulatedGrossUnrealizedGainBeforeTax

mktx:MarketableSecuritiesAccumulatedGrossUnrealizedGainBeforeTax


Marketable
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value908000.0415000.01350000.0233000.01311000.0393000.02346000.02044000.01949000.0952000.0260000.024000.029000.028000.0477000.0414000.0309000.0198000.0175000.0
Percentage of MarketableSecuritiesAccumulatedGrossUnrealizedGainBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:MarketableSecuritiesAccumulatedGrossUnrealizedLossBeforeTax

mktx:MarketableSecuritiesAccumulatedGrossUnrealizedLossBeforeTax


Marketable
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value-231000.0176000.01657000.019000.033000.0116000.0389000.01285000.01142000.01454000.01631000.0789000.0317000.0400000.0370000.0450000.0
Percentage of MarketableSecuritiesAccumulatedGrossUnrealizedLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:MarketableSecuritiesAfterOneThroughFiveYearsFairValue

mktx:MarketableSecuritiesAfterOneThroughFiveYearsFairValue


Marketable
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value247.1179.8219.912545710911910493105959610910810498877671788047
Percentage of MarketableSecuritiesAfterOneThroughFiveYearsFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:MarketableSecuritiesAmortizedCost

mktx:MarketableSecuritiesAmortizedCost


Marketable
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value34232630130136228233230221241237251245239237237218194
Percentage of MarketableSecuritiesAmortizedCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:MarketableSecuritiesWithinOneYearFairValue

mktx:MarketableSecuritiesWithinOneYearFairValue


Marketable
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value10171821777712011612712913414015313513013313813111799686637
Percentage of MarketableSecuritiesWithinOneYearFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:MaximumPermittedInvestmentsAndLoansInBrokerDealerSubsidiary us-gaap:CreditFacility

mktx:MaximumPermittedInvestmentsAndLoansInBrokerDealerSubsidiary

us-gaap:LetterOfCredit


Maximum
Period End2020-12-31
Value500000.0
Percentage of MaximumPermittedInvestmentsAndLoansInBrokerDealerSubsidiary100.0

mktx:MoneyMarketFundsFairValueDisclosure

mktx:MoneyMarketFundsFairValueDisclosure


Money
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value1911202415315299163108155112112101618825112658373631615146516280809090738999831251069611196
Percentage of MoneyMarketFundsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:MoneyMarketFundsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel1


Money
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value1911202415315299163108155112112101618825112658373631615146516280809090738999831251069611196
Percentage of MoneyMarketFundsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:MutualFundInvestmentsAndDeferredCompensationObligationAtFairValue

mktx:MutualFundInvestmentsAndDeferredCompensationObligationAtFairValue


Mutual
Period End2020-12-312019-12-312019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value8900000.06200000.05800000.05600000.04100000.04500000.04400000.04300000.03200000.03100000.02900000.02800000.01300000.01300000.01300000.01300000.0
Percentage of MutualFundInvestmentsAndDeferredCompensationObligationAtFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:OtherDeposits us-gaap:BalanceSheetLocation

mktx:OtherDeposits

us-gaap:PrepaidExpensesAndOtherCurrentAssets


Other
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value90000.090000.090000.070000.04129000.0
Percentage of OtherDeposits100.0100.0100.0100.0100.0

mktx:ReceivableFromSubsidiaries us-gaap:ConsolidatedEntities

mktx:ReceivableFromSubsidiaries

srt:ParentCompany


Receivable
Period End2020-12-312019-12-31
Value415.997
Percentage of ReceivableFromSubsidiaries100.0100.0

mktx:ReceivablesFromBrokersDealersClearingOrganizationsAndCustomers

mktx:ReceivablesFromBrokersDealersClearingOrganizationsAndCustomers


Receivables
Period End2021-06-302021-03-312020-12-312020-09-30
Value475564279380
Percentage of ReceivablesFromBrokersDealersClearingOrganizationsAndCustomers100.0100.0100.0100.0

mktx:SecuritiesFailedToDeliverBrokerDealers

mktx:SecuritiesFailedToDeliverBrokerDealers


Securities
Period End2021-06-302021-03-312020-12-312020-09-30
Value13115593111
Percentage of SecuritiesFailedToDeliverBrokerDealers100.0100.0100.0100.0

mktx:SecuritiesFailedToDeliverCustomers

mktx:SecuritiesFailedToDeliverCustomers


Securities
Period End2021-06-302021-03-312020-12-312020-09-30
Value25928887184
Percentage of SecuritiesFailedToDeliverCustomers100.0100.0100.0100.0

mktx:SecuritiesFailedToReceiveBrokerDealers

mktx:SecuritiesFailedToReceiveBrokerDealers


Securities
Period End2021-06-302021-03-312020-12-312020-09-30
Value2021567084
Percentage of SecuritiesFailedToReceiveBrokerDealers100.0100.0100.0100.0

mktx:SecuritiesFailedToReceiveCustomers

mktx:SecuritiesFailedToReceiveCustomers


Securities
Period End2021-06-302021-03-312020-12-312020-09-30
Value721446046
Percentage of SecuritiesFailedToReceiveCustomers100.0100.0100.0100.0

mktx:TradingSecuritiesAccumulatedGrossUnrealizedGainBeforeTax

mktx:TradingSecuritiesAccumulatedGrossUnrealizedGainBeforeTax


Trading
Period End2021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value415000.0233000.0144000.020000.01625000.01312000.01268000.0714000.0233000.010000.017000.017000.0468000.0396000.0298000.0185000.0162000.0349000.0409000.0242000.0
Percentage of TradingSecuritiesAccumulatedGrossUnrealizedGainBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:TradingSecuritiesAccumulatedGrossUnrealizedGainBeforeTax us-gaap:InvestmentType

mktx:MutualFundsHeldInRabbiTrust


Trading
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value907000.0330000.01209000.0126000.054000.05000.01044000.0695000.0670000.0365000.0438000.0329000.0220000.0117000.0115000.0161000.0117000.086000.0
Percentage of TradingSecuritiesAccumulatedGrossUnrealizedGainBeforeTax0.079.50.054.137.525.064.253.052.851.193.683.173.863.271.046.128.635.5

us-gaap:CorporateDebtSecurities


Trading
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value85000.0141000.0107000.090000.015000.014000.030000.07000.02000.08000.010000.017000.017000.030000.067000.078000.068000.047000.0188000.0292000.0156000.0
Percentage of TradingSecuritiesAccumulatedGrossUnrealizedGainBeforeTax20.50.045.962.575.00.92.30.60.33.4100.0100.0100.06.416.926.236.829.053.971.464.5

us-gaap:USTreasurySecurities


Trading
Period End2021-06-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value1000.0567000.0587000.0591000.0347000.0225000.0
Percentage of TradingSecuritiesAccumulatedGrossUnrealizedGainBeforeTax0.034.944.746.648.696.6

mktx:TradingSecuritiesAccumulatedGrossUnrealizedLossBeforeTax

mktx:TradingSecuritiesAccumulatedGrossUnrealizedLossBeforeTax


Trading
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-231000.0159000.01354000.014000.09000.049000.0163000.0668000.0383000.0600000.0703000.0306000.0122000.0170000.0191000.0234000.012000.015000.019000.0
Percentage of TradingSecuritiesAccumulatedGrossUnrealizedLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mktx:TradingSecuritiesAccumulatedGrossUnrealizedLossBeforeTax us-gaap:InvestmentType

mktx:MutualFundsHeldInRabbiTrust


Trading
Period End2020-09-302020-06-302020-03-312018-12-312018-09-302018-06-302018-03-31
Value-231000.0158000.01178000.0247000.0-137000.0-23000.019000.0
Percentage of TradingSecuritiesAccumulatedGrossUnrealizedLossBeforeTax100.099.487.037.0-35.8-3.82.7

srt:AlternativeExcessNetCapital

srt:AlternativeExcessNetCapital


Alternative
Period End2021-03-312020-12-312020-09-30
Value493435305
Percentage of AlternativeExcessNetCapital100.0100.0100.0

srt:AlternativeExcessNetCapital us-gaap:CounterpartyName

mktx:USBrokerDealerSubsidiaries


Alternative
Period End2021-06-30
Value343
Percentage of AlternativeExcessNetCapital0.0

mktx:USSubsidiaries


Alternative
Period End2021-06-30
Value551
Percentage of AlternativeExcessNetCapital0.0

srt:AlternativeNetCapitalRequirement1

srt:AlternativeNetCapitalRequirement1


Alternative
Period End2021-03-312020-12-312020-09-30
Value312123
Percentage of AlternativeNetCapitalRequirement1100.0100.0100.0

srt:AlternativeNetCapitalRequirement1 us-gaap:CounterpartyName

mktx:USBrokerDealerSubsidiaries


Alternative
Period End2021-06-30
Value3.6
Percentage of AlternativeNetCapitalRequirement10.0

mktx:USSubsidiaries


Alternative
Period End2021-06-30
Value22
Percentage of AlternativeNetCapitalRequirement10.0

srt:PayablesToBrokerDealersAndClearingOrganizations

srt:PayablesToBrokerDealersAndClearingOrganizations


Payables
Period End2021-06-302021-03-312020-12-312020-09-30
Value278308133138
Percentage of PayablesToBrokerDealersAndClearingOrganizations100.0100.0100.0100.0

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302012-12-31
Value658044252234191617132919201414121416151515161213131211111819142012
Percentage of AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Accounts
Period End2020-12-312019-12-312018-12-31
Value9.3419.25420
Percentage of AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent21.148.070.1

us-gaap:AccountsReceivableNet

us-gaap:AccountsReceivableNet


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value878779819993627266705762616752635556505662524049464633364039343641353133333336313425
Percentage of AccountsReceivableNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccountsReceivableNet us-gaap:ConsolidatedEntities

srt:ParentCompany


Accounts
Period End2020-12-312019-12-312018-12-31
Value0.1780.0630.059
Percentage of AccountsReceivableNet0.20.10.1

us-gaap:AllowanceForDoubtfulAccountsReceivable

us-gaap:AllowanceForDoubtfulAccountsReceivable


Allowance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-31
Value57000.0107000.0163000.0166000.0200000.083000.057000.0146000.076000.0114000.080000.091000.074000.096000.0178000.071000.084000.057000.082000.0194000.0178000.0119000.0109000.039000.099000.062000.03000.083000.014000.0170000.0133000.076000.0131000.074000.075000.0322000.0406000.0402000.01086000.0191000.077000.0427000.0900000.0
Percentage of AllowanceForDoubtfulAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetsFairValueDisclosure

us-gaap:AssetsFairValueDisclosure


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value56344853286281327399339379351350351305327263246244252208188178146146113114127137145154157131104116134179164156189168
Percentage of AssetsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

mktx:CashSegregatedUnderFederalRegulations, us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-30
Value50505050
Percentage of AssetsFairValueDisclosure88.5146.1103.993.1

mktx:ReceivablesFromBrokerDealersClearingOrganizationsAndCustomers, us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-30
Value811119776
Percentage of AssetsFairValueDisclosure143.9325.5201.5142.9

mktx:ReceivablesFromBrokerDealersClearingOrganizationsAndCustomers, us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-30
Value394453182304
Percentage of AssetsFairValueDisclosure696.61322.3379.7565.5

us-gaap:AccountsReceivable, us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-03-31
Value87
Percentage of AssetsFairValueDisclosure255.1

us-gaap:AccountsReceivable, us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302020-12-312019-12-31
Value877962
Percentage of AssetsFairValueDisclosure153.9165.218.9

us-gaap:CashAndCashEquivalents, us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value413390460310270
Percentage of AssetsFairValueDisclosure730.71140.2956.9577.382.5

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

mktx:CashSegregatedUnderFederalRegulations, us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-30
Value50505050
Percentage of AssetsFairValueDisclosure88.5146.1103.993.1

mktx:CashSegregatedUnderFederalRegulations, us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-30
Value50505050
Percentage of AssetsFairValueDisclosure88.5146.1103.993.1

mktx:ReceivablesFromBrokerDealersClearingOrganizationsAndCustomers, us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-30
Value475564279380
Percentage of AssetsFairValueDisclosure840.41647.8581.2708.4

mktx:ReceivablesFromBrokerDealersClearingOrganizationsAndCustomers, us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-30
Value475564279380
Percentage of AssetsFairValueDisclosure840.41647.8581.2708.4

us-gaap:AccountsReceivable, us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312019-12-31
Value87877962
Percentage of AssetsFairValueDisclosure153.9255.1165.218.9

us-gaap:AccountsReceivable, us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312019-12-31
Value87877962
Percentage of AssetsFairValueDisclosure153.9255.1165.218.9

us-gaap:CashAndCashEquivalents, us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value413390460310270
Percentage of AssetsFairValueDisclosure730.71140.2956.9577.382.5

us-gaap:CashAndCashEquivalents, us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value413390460310270
Percentage of AssetsFairValueDisclosure730.71140.2956.9577.382.5

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementFrequency

mktx:CashSegregatedUnderFederalRegulations, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-30
Value50505050
Percentage of AssetsFairValueDisclosure88.5146.1103.993.1

mktx:ReceivablesFromBrokerDealersClearingOrganizationsAndCustomers, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-30
Value475564279380
Percentage of AssetsFairValueDisclosure840.41647.8581.2708.4

us-gaap:AccountsReceivable, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312019-12-31
Value87877962
Percentage of AssetsFairValueDisclosure153.9255.1165.218.9

us-gaap:CashAndCashEquivalents, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value413390460310270
Percentage of AssetsFairValueDisclosure730.71140.2956.9577.382.5

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel1


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value1911202415315299163108155112112101618825112658373631615146516280809090738999831251069611196
Percentage of AssetsFairValueDisclosure33.933.043.345.453.754.430.541.031.941.032.032.229.020.027.19.64.510.923.218.019.618.042.134.840.745.548.958.555.159.057.455.885.985.662.069.964.561.758.757.2

us-gaap:FairValueInputsLevel2


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value37222729132128227235230223239237249244238237235217194170151146859567626457656367581416515458597872
Percentage of AssetsFairValueDisclosure66.167.056.754.646.345.669.559.068.159.068.067.871.080.072.990.495.589.176.882.080.482.057.965.259.354.551.141.544.941.042.644.214.114.438.030.135.538.341.342.8

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

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value545640607437270
Percentage of AssetsFairValueDisclosure963.11866.81262.3813.282.5

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value48145326230462
Percentage of AssetsFairValueDisclosure850.51322.3544.9565.518.9

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value10261093870741332
Percentage of AssetsFairValueDisclosure1813.63189.11807.31378.7101.4

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value10261093870741332
Percentage of AssetsFairValueDisclosure1813.63189.11807.31378.7101.4

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsNonrecurring


Assets
Period End2021-06-302021-03-312020-12-312020-09-302019-12-31
Value10261093870741332
Percentage of AssetsFairValueDisclosure1813.63189.11807.31378.7101.4

us-gaap:BankOverdrafts us-gaap:ConsolidatedEntities, us-gaap:StatementGeographical, us-gaap:BalanceSheetLocation

us-gaap:BankOverdrafts

srt:Subsidiaries, country:GB, mktx:AccountsPayableAccruedExpensesAndOtherLiabilities


Bank
Period End2021-03-31
Value34
Percentage of BankOverdrafts100.0

srt:Subsidiaries, mktx:USAndUK, mktx:AccountsPayableAccruedExpensesAndOtherLiabilities


Bank
Period End2021-06-30
Value1.0
Percentage of BankOverdrafts0.0

us-gaap:BusinessAcquisitionCostOfAcquiredEntityTransactionCosts us-gaap:BusinessAcquisition

us-gaap:BusinessAcquisitionCostOfAcquiredEntityTransactionCosts

mktx:MuniBrokersLLC


Business
Period End2020-09-30
Value20
Percentage of BusinessAcquisitionCostOfAcquiredEntityTransactionCosts100.0

us-gaap:BusinessCombinationContingentConsiderationLiability

us-gaap:BusinessCombinationContingentConsiderationLiability


Business
Period End2021-06-302020-12-31
Value3615
Percentage of BusinessCombinationContingentConsiderationLiability100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiability us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel3


Business
Period End2021-06-302020-12-31
Value3615
Percentage of BusinessCombinationContingentConsiderationLiability100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent


Business
Period End2021-06-30
Value22
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent100.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent us-gaap:BalanceSheetLocation, us-gaap:BusinessAcquisition

mktx:AccountsPayableAccruedExpensesAndOtherLiabilities, mktx:MuniBrokersLimitedLiabilityCompany


Business
Period End2021-04-09
Value22
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent0.0

mktx:AccountsPayableAccruedExpensesAndOtherLiabilities, mktx:RegulatoryServicesGMBHOfDeutscheBorseGroup


Business
Period End2020-11-30
Value14
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent0.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent us-gaap:Range, us-gaap:BusinessAcquisition

srt:Maximum, mktx:MuniBrokersLLC


Business
Period End2020-09-30
Value25
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent0.0

srt:Maximum, mktx:MuniBrokersLimitedLiabilityCompany


Business
Period End2021-04-09
Value25
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent0.0

srt:Maximum, mktx:RegulatoryServicesGMBHOfDeutscheBorseGroup


Business
Period End2020-11-30
Value24
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent0.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent us-gaap:Range, us-gaap:BusinessAcquisition, us-gaap:SubsequentEventType

srt:Maximum, mktx:MuniBrokersLimitedLiabilityCompany, us-gaap:SubsequentEvent


Business
Period End2021-04-09
Value25
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent0.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles

mktx:MuniBrokersLimitedLiabilityCompany


Business
Period End2021-04-09
Value32
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles100.0

mktx:RegulatoryServicesGMBHOfDeutscheBorseGroup


Business
Period End2020-11-30
Value37
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles0.0

us-gaap:CashAndSecuritiesSegregatedUnderFederalAndOtherRegulations

us-gaap:CashAndSecuritiesSegregatedUnderFederalAndOtherRegulations


Cash
Period End2021-06-302021-03-312020-12-312020-09-30
Value50505050
Percentage of CashAndSecuritiesSegregatedUnderFederalAndOtherRegulations100.0100.0100.0100.0

us-gaap:CashAndSecuritiesSegregatedUnderFederalAndOtherRegulations us-gaap:BalanceSheetLocation

mktx:CashSegregatedUnderFederalAndOtherRegulations


Cash
Period End2021-06-302021-03-312020-12-312020-09-30
Value50505050
Percentage of CashAndSecuritiesSegregatedUnderFederalAndOtherRegulations100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-31
Value545552608437424365274321287262247211170157168169200
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations us-gaap:ConsolidatedEntities

srt:ParentCompany


Cash
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value5548956253
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations9.217.638.737.331.7

us-gaap:ContractWithCustomerLiability

us-gaap:ContractWithCustomerLiability


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value4695000.04825000.04248000.05092000.04068000.03950000.03499000.03731000.03810000.03545000.02810000.03785000.03595000.02660000.0
Percentage of ContractWithCustomerLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiability us-gaap:ProductOrService

mktx:InformationServices


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value3296000.03166000.03203000.03512000.02608000.02398000.02138000.02552000.02371000.02117000.01959000.02399000.02203000.01763000.0
Percentage of ContractWithCustomerLiability70.265.675.469.064.160.761.168.462.259.769.763.461.366.3

mktx:PostTradeServices


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value1399000.01659000.01045000.01580000.01460000.01552000.01361000.01179000.01439000.01428000.0851000.01386000.01392000.0897000.0
Percentage of ContractWithCustomerLiability29.834.424.631.035.939.338.931.637.840.330.336.638.733.7

us-gaap:ContractualObligation

us-gaap:ContractualObligation


Contractual
Period End2021-06-302021-03-312020-12-312020-09-30
Value1200000.01700000.02100000.02600000.0
Percentage of ContractualObligation100.0100.0100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months us-gaap:InvestmentType

us-gaap:DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months

us-gaap:CorporateDebtSecurities


Debt
Period End2020-12-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1.36911512721142780177
Percentage of DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredIncomeTaxAssetsNet


Deferred
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-31
Value52000.033000.058000.0501000.03163000.01595000.01417000.03424000.02256000.01453000.0830000.01737000.08457000.07370000.06829000.08562000.07399000.06057000.05197000.09229000.08238000.06061000.06972000.0
Percentage of DeferredIncomeTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsGross

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
Value24268.5361121222121151322
Percentage of DeferredTaxAssetsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost


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
Value3.6824.9264.9674.534119.1157.2666.0225.2965.3126.945
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseOther

us-gaap:DeferredTaxAssetsTaxDeferredExpenseOther


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
Value1968000.0892000.02966000.01143000.01468000.03745000.03482000.03206000.02839000.03280000.01958000.0
Percentage of DeferredTaxAssetsTaxDeferredExpenseOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value7828000.05306000.03776000.03479000.04923000.04344000.04495000.04163000.02752000.01980000.01210000.0
Percentage of DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssets

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssets


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
Value2852000.01120000.0898000.0967000.01037000.01310000.01854000.02331000.0524000.01085000.01627000.0
Percentage of DeferredTaxLiabilitiesGoodwillAndIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DepositsPaidForSecuritiesBorrowedAtCarryingValue

us-gaap:DepositsPaidForSecuritiesBorrowedAtCarryingValue


Deposits
Period End2021-06-302021-03-312020-12-312020-09-30
Value811119776
Percentage of DepositsPaidForSecuritiesBorrowedAtCarryingValue100.0100.0100.0100.0

us-gaap:DepositsPaidForSecuritiesBorrowedAtCarryingValue us-gaap:BalanceSheetLocation

mktx:ReceivablesFromBrokerDealersClearingOrganizationsAndCustomers


Deposits
Period End2021-06-302021-03-312020-12-312020-09-30
Value811119776
Percentage of DepositsPaidForSecuritiesBorrowedAtCarryingValue100.0100.0100.0100.0

us-gaap:DerivativeAssetNotionalAmount us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeAssetNotionalAmount

us-gaap:ForeignExchangeContract


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value1821971571591771641581341261221079989878588796967595251454238333130353329282715
Percentage of DerivativeAssetNotionalAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral

us-gaap:ForeignExchangeContract


Derivative
Period End2021-06-30
Value1595000.0
Percentage of DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral100.0

us-gaap:DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral us-gaap:DerivativeInstrumentRisk, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:ForeignExchangeContract, us-gaap:FairValueInputsLevel2


Derivative
Period End2021-06-30
Value1595000.0
Percentage of DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral100.0

us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral

us-gaap:ForeignExchangeContract


Derivative
Period End2020-12-31
Value805000.0
Percentage of DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral100.0

us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral us-gaap:DerivativeInstrumentRisk, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:ForeignExchangeContract, us-gaap:FairValueInputsLevel2


Derivative
Period End2020-12-31
Value805000.0
Percentage of DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral100.0

us-gaap:DerivativeFairValueOfDerivativeNet us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeFairValueOfDerivativeNet

us-gaap:ForeignExchangeContract


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-31
Value1595000.0-1349000.0-805000.0-1932000.01396000.0-7379000.0-2772000.0231000.0-978000.01096000.0-1021000.01469000.0-262000.0288000.0-702000.0591000.0-2346000.0-1093000.0-266000.0318000.05518000.0-1130000.0354000.0186000.0-107000.051000.0103000.0177000.0-472000.0
Percentage of DerivativeFairValueOfDerivativeNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeNet us-gaap:DerivativeInstrumentRisk, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:ForeignExchangeContract, us-gaap:FairValueInputsLevel2


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-31
Value-1349000.0-805000.0-1932000.01396000.0-7379000.0-2772000.0231000.0-978000.01096000.0-1021000.01469000.0-262000.0288000.0-702000.0591000.0-2346000.0-1093000.0-266000.0318000.05518000.0-1130000.0354000.0186000.0-107000.051000.0103000.0177000.0-472000.0
Percentage of DerivativeFairValueOfDerivativeNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeNotionalAmount us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeNotionalAmount

us-gaap:ForeignExchangeContract


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-31
Value183196157157179156155134106
Percentage of DerivativeNotionalAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeRelatedLiabilitiesCurrentAndNoncurrent

us-gaap:EmployeeRelatedLiabilitiesCurrentAndNoncurrent


Employee
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value392862503921473526163931231536312313342820102922168.962518126.1832319125.7511915105.81719151117
Percentage of EmployeeRelatedLiabilitiesCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeRelatedLiabilitiesCurrentAndNoncurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Employee
Period End2020-12-312019-12-312018-12-31
Value106.5435.667
Percentage of EmployeeRelatedLiabilitiesCurrentAndNoncurrent16.413.814.5

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized


Employee
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value46505.9387.88.64.34.11.50.41.81.82.3
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized us-gaap:AwardType

mktx:RestrictedStockAndPerformanceShares


Employee
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value27312318181611119.7
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized457.6397.4270.9432.6456.11100.02850.0622.2538.9

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

us-gaap:FinancialLiabilitiesFairValueDisclosure

us-gaap:FairValueInputsLevel2, mktx:PayablesToBrokerDealersClearingOrganizationsAndCustomers, us-gaap:FairValueMeasurementsNonrecurring


Financial
Period End2021-06-302021-03-312020-12-312020-09-30
Value278308133138
Percentage of FinancialLiabilitiesFairValueDisclosure100.0100.0100.0100.0

us-gaap:FinancialLiabilitiesFairValueDisclosure us-gaap:FairValueByLiabilityClass, us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

mktx:PayablesToBrokerDealersClearingOrganizationsAndCustomers, us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Financial
Period End2021-06-302021-03-312020-12-312020-09-30
Value278308133138
Percentage of FinancialLiabilitiesFairValueDisclosure100.0100.0100.0100.0

mktx:PayablesToBrokerDealersClearingOrganizationsAndCustomers, us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Financial
Period End2021-06-302021-03-312020-12-312020-09-30
Value278308133138
Percentage of FinancialLiabilitiesFairValueDisclosure100.0100.0100.0100.0

us-gaap:FinancialLiabilitiesFairValueDisclosure us-gaap:FairValueByLiabilityClass, us-gaap:FairValueByMeasurementFrequency

mktx:PayablesToBrokerDealersClearingOrganizationsAndCustomers, us-gaap:FairValueMeasurementsNonrecurring


Financial
Period End2021-06-302021-03-312020-12-312020-09-30
Value278308133138
Percentage of FinancialLiabilitiesFairValueDisclosure100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value2016131211109.9869.4729.3839.2939.1929.19.0078.9258.8218.7238.628.5158.4178.3328.2428.1637.7577.1956.6366.0515.4944.9364.3813.8053.2342.5669.2188.4828.047.6957.346.9856.635.162
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization us-gaap:FiniteLivedIntangibleAssetsByMajorClass

mktx:TechnologyAndOtherIntangibles


Finite
Period End2021-06-302021-03-312020-12-31
Value6.8526.5236.523
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization34.339.447.0

mktx:TradenamesAndPatents


Finite
Period End2020-12-312019-12-312018-12-31
Value0.3730.3850.37
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization2.73.94.0

us-gaap:CustomerRelationships


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value13107.3695.4814.7934.1153.4512.9522.8632.7732.6722.582.4872.4052.3012.2032.11.9951.8971.8121.7221.6431.5531.4641.3781.2671.1831.0981.0170.9140.8160.6332.7512.4992.3642.2722.1812.091.9991.584
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization65.760.653.045.742.438.634.631.230.529.829.128.427.626.926.125.324.423.422.521.720.920.120.020.320.820.921.522.223.224.025.224.729.829.529.429.529.729.930.230.7

us-gaap:NoncompeteAgreements


Finite
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value0.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.3590.3270.2960.2640.2320.2010.1690.1370.1060.0741.3021.2711.2141.1521.0881.0250.9620.71
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization2.73.23.43.63.84.04.04.14.14.24.24.34.34.44.44.54.54.64.64.74.64.54.54.44.24.13.93.63.32.914.115.015.115.014.814.714.513.8

us-gaap:TechnologyBasedIntangibleAssets


Finite
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value5.775.775.775.775.775.775.775.775.775.775.775.775.775.775.775.775.775.775.775.775.4925.0764.6594.2423.8263.4092.9922.159
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization41.548.151.054.157.860.961.562.162.863.464.164.665.466.166.967.868.669.370.070.770.870.570.270.169.669.168.366.8

us-gaap:TradeNames


Finite
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value0.3720.3710.4080.3850.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.3530.3280.3030.2780.2530.2280.2030.1780.1530.1280.6230.5980.570.5450.5190.4930.4670.363
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization3.13.33.83.93.93.94.04.04.14.14.14.24.24.34.34.44.44.54.54.64.64.64.64.64.64.64.74.75.06.87.17.17.17.17.17.07.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths


Finite
Period End2021-06-302021-03-312020-12-312020-09-30
Value166.95.75.7
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear


Finite
Period End2021-06-302021-03-312020-09-30
Value135.73.2
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive


Finite
Period End2020-12-31
Value5700000.0
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearFive100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour


Finite
Period End2021-06-302021-03-312020-12-312020-09-30
Value125.76.76.7
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearFour100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree


Finite
Period End2021-06-302021-03-312020-12-312020-09-30
Value146.77.97.9
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearThree100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo


Finite
Period End2021-06-302021-03-312020-12-312020-09-30
Value177.96.96.9
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsGross

us-gaap:FiniteLivedIntangibleAssetsGross


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value139107109707070701212121212121212121212121212121212121212121212121220209.399.399.399.399.399.39
Percentage of FiniteLivedIntangibleAssetsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsGross us-gaap:FiniteLivedIntangibleAssetsByMajorClass

mktx:TechnologyAndOtherIntangibles


Finite
Period End2021-06-302021-03-312020-12-31
Value116.556.55
Percentage of FiniteLivedIntangibleAssetsGross8.26.16.0

mktx:TradenamesAndPatents


Finite
Period End2020-12-312019-12-312018-12-31
Value0.40.490.37
Percentage of FiniteLivedIntangibleAssetsGross0.40.73.0

us-gaap:CustomerRelationships


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value128100102646464645.6275.6345.6395.6345.6395.6425.6555.6475.6455.6395.635.6285.6385.6445.6615.6685.6745.6845.6695.6825.6925.7075.75.6985.6928.9858.9853.533.533.533.533.533.53
Percentage of FiniteLivedIntangibleAssetsGross91.893.994.090.890.890.690.646.346.446.446.446.446.446.446.446.446.446.346.346.446.446.546.546.546.646.546.646.646.746.646.646.643.843.837.637.637.637.637.637.6

us-gaap:NoncompeteAgreements


Finite
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value0.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.380.381.641.641.261.261.261.261.261.26
Percentage of FiniteLivedIntangibleAssetsGross0.30.50.50.50.53.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.18.08.013.413.413.413.413.413.4

us-gaap:TradeNames


Finite
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value0.40.40.490.490.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.370.890.890.590.590.590.590.590.59
Percentage of FiniteLivedIntangibleAssetsGross0.60.60.70.73.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.04.34.36.36.36.36.36.36.3

us-gaap:IncomeTaxReceivable us-gaap:ConsolidatedEntities

us-gaap:IncomeTaxReceivable

srt:ParentCompany


Income
Period End2020-12-312019-12-31
Value9028000.03219000.0
Percentage of IncomeTaxReceivable100.0100.0

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths


Lessee
Period End2021-06-302021-03-312020-12-312020-09-30
Value10101211
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths100.0100.0100.0100.0

us-gaap:LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear

us-gaap:LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear


Lessee
Period End2021-06-302021-03-312020-09-30
Value5956000.09177000.02417000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear100.0100.0100.0

us-gaap:LiabilitiesFairValueDisclosure

us-gaap:LiabilitiesFairValueDisclosure


Liabilities
Period End2020-12-31
Value15
Percentage of LiabilitiesFairValueDisclosure100.0

us-gaap:LiabilitiesFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel2


Liabilities
Period End2020-12-31
Value0.805
Percentage of LiabilitiesFairValueDisclosure5.1

us-gaap:FairValueInputsLevel3


Liabilities
Period End2020-12-31
Value15
Percentage of LiabilitiesFairValueDisclosure94.9

us-gaap:LineOfCreditFacilityCurrentBorrowingCapacity us-gaap:CreditFacility

us-gaap:LineOfCreditFacilityCurrentBorrowingCapacity

us-gaap:LetterOfCredit


Line
Period End2020-12-312020-08-192015-10-31
Value0.450.1100
Percentage of LineOfCreditFacilityCurrentBorrowingCapacity100.0100.0100.0

us-gaap:RevolvingCreditFacility


Line
Period End2020-11-302020-11-132020-09-302020-08-31
Value500500450100
Percentage of LineOfCreditFacilityCurrentBorrowingCapacity0.00.00.00.0

us-gaap:LineOfCreditFacilityRemainingBorrowingCapacity us-gaap:CreditFacility

us-gaap:LineOfCreditFacilityRemainingBorrowingCapacity

us-gaap:RevolvingCreditFacility


Line
Period End2021-06-302021-03-312020-12-312020-09-30
Value499499499449
Percentage of LineOfCreditFacilityRemainingBorrowingCapacity100.0100.0100.0100.0

us-gaap:MarketableSecurities

us-gaap:MarketableSecurities


Marketable
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value3524283113113523023523122224023624924423923723721819484
Percentage of MarketableSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MarketableSecurities us-gaap:ConsolidatedEntities

srt:ParentCompany


Marketable
Period End2020-12-312019-12-312018-12-31
Value4.811141149
Percentage of MarketableSecurities17.161.362.2

us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent

us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-03-31
Value5.95.95.95.90.0590.0590.0590.06
Percentage of OperatingLeaseWeightedAverageDiscountRatePercent100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherPayablesToBrokerDealersAndClearingOrganizations

us-gaap:OtherPayablesToBrokerDealersAndClearingOrganizations


Other
Period End2021-06-302021-03-312020-12-312020-09-30
Value3440000.06988000.01625000.07097000.0
Percentage of OtherPayablesToBrokerDealersAndClearingOrganizations100.0100.0100.0100.0

us-gaap:OtherReceivablesFromBrokerDealersAndClearingOrganizations

us-gaap:OtherReceivablesFromBrokerDealersAndClearingOrganizations


Other
Period End2021-06-302021-03-312020-12-312020-09-30
Value3391000.09435000.01893000.08204000.0
Percentage of OtherReceivablesFromBrokerDealersAndClearingOrganizations100.0100.0100.0100.0

us-gaap:PrepaidExpenseAndOtherAssets

us-gaap:PrepaidExpenseAndOtherAssets


Prepaid
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value332529264120301822172218211718162113111113129.887.173127.2076.6858.8129.3331010118.9318.0968.584136.8288.46510127.923
Percentage of PrepaidExpenseAndOtherAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PrepaidExpenseAndOtherAssets us-gaap:ConsolidatedEntities

srt:ParentCompany


Prepaid
Period End2020-12-312019-12-312018-12-31
Value4.5913.5064.439
Percentage of PrepaidExpenseAndOtherAssets15.811.419.8

us-gaap:ReceivablesFromBrokersDealersAndClearingOrganizations

us-gaap:ReceivablesFromBrokersDealersAndClearingOrganizations


Receivables
Period End2021-06-302021-03-312020-12-312020-09-30
Value475564279380
Percentage of ReceivablesFromBrokersDealersAndClearingOrganizations100.0100.0100.0100.0

us-gaap:RevenueRemainingPerformanceObligation

us-gaap:RevenueRemainingPerformanceObligation


Revenue
Period End2021-06-302021-03-312020-12-312020-09-30
Value21212127
Percentage of RevenueRemainingPerformanceObligation100.0100.0100.0100.0

us-gaap:SecuritiesReserveDepositRequiredAndMade

us-gaap:SecuritiesReserveDepositRequiredAndMade


Securities
Period End2021-06-302021-03-312020-12-312020-09-30
Value50505050
Percentage of SecuritiesReserveDepositRequiredAndMade100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue

us-gaap:RestrictedStock


Share
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
Value224.63154.27112.4788.7771.556.2441.8331.8621.8815.6911.239.64
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice


Share
Period End2020-12-31
Value137.78
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue


Share
Period End2020-12-31
Value134
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue100.0

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1


Sharebased
Period End2020-12-31
Value43
Percentage of SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1100.0

us-gaap:TaxesPayableCurrentAndNoncurrent

us-gaap:TaxesPayableCurrentAndNoncurrent


Taxes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-31
Value4148423424201613121816121218134.5074.686157.5823.6343.0104.4634.417.0599.5835.943.6683.975
Percentage of TaxesPayableCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TaxesPayableCurrentAndNoncurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Taxes
Period End2020-12-312018-12-31
Value3.4572.612
Percentage of TaxesPayableCurrentAndNoncurrent8.115.9

us-gaap:TradingSecuritiesDebt

us-gaap:TradingSecuritiesDebt


Trading
Period End2021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value24312934929486899394
Percentage of TradingSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TradingSecuritiesDebt us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:InvestmentType

us-gaap:FairValueInputsLevel2, mktx:MutualFundsHeldInRabbiTrust


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
Value10108.8898.0377.5766.5076.2175.8685.8435.6464.13.167
Percentage of TradingSecuritiesDebt0.043.20.025.725.918.76.76.26.86.34.43.4

us-gaap:FairValueInputsLevel2, us-gaap:CorporateDebtSecurities


Trading
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1319232128313353567191
Percentage of TradingSecuritiesDebt56.80.074.374.181.333.635.561.463.277.296.6

us-gaap:FairValueInputsLevel2, us-gaap:USTreasurySecurities


Trading
Period End2021-06-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value245555272717
Percentage of TradingSecuritiesDebt0.059.758.331.830.518.4

us-gaap:TradingSecuritiesDebt us-gaap:InvestmentType

mktx:MutualFundsHeldInRabbiTrust


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
Value10108.8898.0377.5766.5076.2175.8685.8435.6464.13.167
Percentage of TradingSecuritiesDebt0.043.20.025.725.918.76.76.26.86.34.43.4

us-gaap:CorporateDebtSecurities


Trading
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1319232128313353567191
Percentage of TradingSecuritiesDebt56.80.074.374.181.333.635.561.463.277.296.6

us-gaap:USTreasurySecurities


Trading
Period End2021-06-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value245555272717
Percentage of TradingSecuritiesDebt0.059.758.331.830.518.4

us-gaap:TradingSecuritiesDebtAmortizedCost

us-gaap:TradingSecuritiesDebtAmortizedCost


Trading
Period End2021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value23302936919385889394
Percentage of TradingSecuritiesDebtAmortizedCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TradingSecuritiesDebtAmortizedCost us-gaap:InvestmentType

mktx:MutualFundsHeldInRabbiTrust


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
Value9.941107.687.687.687.685.1735.1735.1735.2814.3472.729
Percentage of TradingSecuritiesDebtAmortizedCost0.042.60.024.926.321.25.75.56.15.94.62.9

us-gaap:CorporateDebtSecurities


Trading
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1319232128313353567291
Percentage of TradingSecuritiesDebtAmortizedCost57.40.075.173.778.834.236.062.363.777.297.1

us-gaap:USTreasurySecurities


Trading
Period End2021-06-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value245454262616
Percentage of TradingSecuritiesDebtAmortizedCost0.060.158.531.630.318.1

us-gaap:UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued

us-gaap:UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued


Unrecognized
Period End2020-12-312019-12-312018-12-31
Value4900000.01200000.0600000.0
Percentage of UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued100.0100.0100.0

Line plots across dimensions of each concept


us-gaap:AllocatedShareBasedCompensationExpense
us-gaap:TitleOfIndividual
(None,)
Allocated Share Based Compensation Expenseus-gaap: Title Of Individual
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:ProductOrService
(None,)
Revenue From Contract With Customer Excluding Assessed Taxus-gaap: Product Or Service
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:StatementGeographical
(None,)
Revenue From Contract With Customer Excluding Assessed Taxus-gaap: Statement Geographical
us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents
(None,)
Stockholders Equityus-gaap: Statement Equity Components
us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType
(None,)
Property Plant And Equipment Grossus-gaap: Property Plant And Equipment By Type
us-gaap:PropertyPlantAndEquipmentNet
us-gaap:StatementGeographical
(None,)
Property Plant And Equipment Netus-gaap: Statement Geographical
us-gaap:FiniteLivedIntangibleAssetsNet
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
(None,)
Finite Lived Intangible Assets Netus-gaap: Finite Lived Intangible Assets By Major Class
us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents
(None,)
Stockholders Equityus-gaap: Statement Equity Components