WLTW


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

Table of contents


us-gaap:StatementEquityComponents
us-gaap:SharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

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

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:CostsAndExpenses

us-gaap:DisposalGroupNotDiscontinuedOperationGainLossOnDisposal

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

us-gaap:IncomeTaxExpenseBenefit
us-gaap:TaxPeriod, us-gaap:UnusualRiskOrUncertaintyByNature

us-gaap:InterestExpense

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:OperatingIncomeLoss

us-gaap:OtherComprehensiveIncomeLossNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherNonoperatingIncomeExpense
us-gaap:ConsolidationItems

us-gaap:ProfitLoss

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:ProductOrService
us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementGeographical
us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementGeographical, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementGeographical
us-gaap:ConsolidationItems, us-gaap:StatementGeographical, us-gaap:StatementBusinessSegments
us-gaap:ProductOrService
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments

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

us-gaap:Assets

us-gaap:Liabilities

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents

us-gaap:AssetsCurrent
dei:LegalEntity, us-gaap:Range
us-gaap:Cash

us-gaap:CashAndCashEquivalentsAtCarryingValue
dei:LegalEntity, us-gaap:Range

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:AccountsReceivableNetCurrent

us-gaap:OtherAssetsCurrent

us-gaap:PrepaidExpenseAndOtherAssetsCurrent

us-gaap:NoncurrentAssets
us-gaap:StatementGeographical

us-gaap:AssetsNoncurrent

us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:AmortizationOfIntangibleAssets
us-gaap:ConsolidationItems
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:PropertyPlantAndEquipmentNet
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill

us-gaap:FiniteLivedIntangibleAssetsNet
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OtherAssetsNoncurrent

us-gaap:DividendsPayableCurrent

us-gaap:LiabilitiesCurrent

us-gaap:LongTermDebtCurrent
us-gaap:DebtInstrument
us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OtherLiabilitiesCurrent

us-gaap:TaxesPayableCurrent

us-gaap:LiabilitiesNoncurrent

us-gaap:LongTermDebt
us-gaap:DebtInstrument
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType

us-gaap:LongTermDebtNoncurrent

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanType

us-gaap:MinorityInterest

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:OperatingLeaseLiability

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:TreasuryStockValue

us-gaap:MinorityInterest

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:IncreaseDecreaseInAccountsReceivable

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss

us-gaap:ProfitLoss

us-gaap:ShareBasedCompensation

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:RepaymentsOfLongTermDebt

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:EffectiveIncomeTaxRateContinuingOperations
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxAssetsNet
us-gaap:BalanceSheetLocation

us-gaap:UnrecognizedTaxBenefits

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:LitigationReserveCurrent

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect

us-gaap:CommonStockDividendsPerShareDeclared
wltw:BalanceSheetDate
us-gaap:ContractWithCustomerLiabilityRevenueRecognized

us-gaap:ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod
us-gaap:IncomeTaxAuthorityName
us-gaap:DeferredForeignIncomeTaxExpenseBenefit
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanContributionsByEmployer
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanInterestCost
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanServiceCost

us-gaap:DefinedContributionPlanEmployerDiscretionaryContributionAmount

us-gaap:Depreciation

us-gaap:DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation
us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation
us-gaap:DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet

us-gaap:DividendsCommonStock
us-gaap:StatementEquityComponents

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements

us-gaap:FinanceLeaseInterestExpense

us-gaap:FinanceLeaseRightOfUseAssetAmortization

us-gaap:FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FinitelivedIntangibleAssetsAcquired1
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax

us-gaap:ForeignCurrencyTransactionGainLossRealized
us-gaap:BusinessAcquisition, us-gaap:RestructuringCostAndReserve, us-gaap:SubsequentEventType
us-gaap:GainLossOnContractTermination

us-gaap:GainLossOnSaleOfBusiness
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:IncomeStatementLocation
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:OtherComprehensiveIncomeLocation

us-gaap:GoodwillForeignCurrencyTranslationGainLoss
us-gaap:StatementBusinessSegments

us-gaap:GoodwillPurchaseAccountingAdjustments
us-gaap:StatementBusinessSegments

us-gaap:GoodwillWrittenOffRelatedToSaleOfBusinessUnit
us-gaap:StatementBusinessSegments

us-gaap:IncomeLossFromEquityMethodInvestments

us-gaap:IncreaseDecreaseInOtherOperatingAssets

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities

us-gaap:InterestAndOtherIncome
us-gaap:StatementBusinessSegments

us-gaap:LaborAndRelatedExpense

us-gaap:LeaseCost
us-gaap:CounterpartyName, us-gaap:LitigationStatus, us-gaap:LossContingenciesByNatureOfContingency
us-gaap:LitigationSettlementAmountAwardedToOtherParty
us-gaap:CounterpartyName, us-gaap:LitigationStatus, us-gaap:SubsequentEventType
us-gaap:LitigationStatus, us-gaap:LossContingenciesByNatureOfContingency
us-gaap:LitigationStatus, us-gaap:LossContingenciesByNatureOfContingency, us-gaap:SubsequentEventType
us-gaap:LitigationStatus, us-gaap:LossContingenciesByNatureOfContingency
us-gaap:LossContingencyAccrualProvision
us-gaap:LossContingenciesByNatureOfContingency

us-gaap:NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest
us-gaap:StatementEquityComponents

us-gaap:NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent

us-gaap:NoncontrollingInterestDecreaseFromDeconsolidation
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents
us-gaap:OciBeforeReclassificationsNetOfTaxAttributableToParent

us-gaap:OperatingLeaseCost
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation
us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax

us-gaap:OtherCostAndExpenseOperating

us-gaap:OtherNoncashIncomeExpense
us-gaap:ConsolidationItems
us-gaap:OtherOperatingIncomeExpenseNet

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsOfDebtIssuanceCosts

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation
us-gaap:BusinessAcquisition
us-gaap:PaymentsToAcquireBusinessesGross

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired

us-gaap:PaymentsToDevelopSoftware

us-gaap:PensionAndOtherPostretirementBenefitsExpenseReversalOfExpenseNoncash

us-gaap:ProceedsFromDivestitureOfBusinessesNetOfCashDivested

us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromIssuanceOfSeniorLongTermDebt

us-gaap:ProceedsFromPaymentsToMinorityShareholders

us-gaap:ProvisionForDoubtfulAccounts
us-gaap:StatementEquityComponents
us-gaap:ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent

us-gaap:ReclassificationFromAociCurrentPeriodTax

us-gaap:ShortTermLeaseCost
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesShareBasedCompensation

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation
us-gaap:StatementEquityComponents

us-gaap:SubleaseIncome

us-gaap:VariableLeaseCost

wltw:AdjustmentsToAdditionalPaidInCapitalForeignCurrencyTranslationGainLoss
us-gaap:StatementEquityComponents

wltw:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndNetSettlements
us-gaap:StatementEquityComponents

wltw:BusinessCombinationIntegrationRelatedCostsCredits
us-gaap:ConsolidationItems
wltw:BusinessCombinationIntegrationRelatedTransactionCosts

wltw:DefinedBenefitPlansPercentageOfObligationFromPlans

wltw:DepreciationNotIncludingIntegrationComponent
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
wltw:DerivativeInstrumentsDesignatedAsHedgingInstrumentsGainLossNet

wltw:DilutiveSecuritiesEffectOnBasicEarningsPerShare

wltw:FiniteLivedIntangibleAssetsDisposed
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

wltw:IncreaseDecreaseInFiduciaryAssets

wltw:IncreaseDecreaseInFiduciaryLiabilities

wltw:IncreaseDecreaseInProvisionForLiabilities
us-gaap:ProductOrService, us-gaap:Range
wltw:IndividualRevenueStreamsPercentageOfTotalRevenue

wltw:MiscellaneousOtherNonOperatingIncomeExpense

wltw:NoncontrollingInterestDecreaseFromSale
us-gaap:StatementEquityComponents

wltw:OperatingLeaseRightOfUseAssetAmortization

wltw:OtherComprehensiveIncomeLossNetOfTaxIncludingPortionAttributableToNonredeemableNoncontrollingInterest
us-gaap:StatementEquityComponents

wltw:PaymentsForDeferredContingentConsiderationFinancingActivities

wltw:PaymentsToAcquireFixedAssetsAndSoftwareForInternalUse

wltw:ReimbursableExpensesAndOther
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments

dei:EntityNumberOfEmployees

us-gaap:AccountsPayableOtherCurrent

us-gaap:AccountsReceivableNetNoncurrent

us-gaap:AccruedSalesCommissionCurrent

us-gaap:AllowanceForDoubtfulAccountsReceivable
us-gaap:FairValueByLiabilityClass, us-gaap:MeasurementInputType
us-gaap:AlternativeInvestmentMeasurementInput
us-gaap:Range, us-gaap:FairValueByLiabilityClass, us-gaap:MeasurementInputType
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:AssetsNet

us-gaap:BilledContractReceivables
us-gaap:LossContingenciesByNatureOfContingency
us-gaap:CapitalLeaseObligations

us-gaap:CapitalizedContractCostNet

us-gaap:CapitalizedContractCostNetCurrent

us-gaap:CapitalizedContractCostNetNoncurrent

us-gaap:ContractWithCustomerAssetNetCurrent

us-gaap:ContractWithCustomerAssetNetNoncurrent

us-gaap:ContractWithCustomerLiability
us-gaap:DebtInstrument
us-gaap:DebtInstrumentAnnualPrincipalPayment

us-gaap:DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible
us-gaap:Range

us-gaap:DeferredCompensationLiabilityClassifiedNoncurrent

us-gaap:DeferredCompensationLiabilityCurrent

us-gaap:DeferredCompensationPlanAssets

us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredIncomeTaxLiabilities
us-gaap:BalanceSheetLocation

us-gaap:DeferredTaxAssetsCapitalLossCarryforwards

us-gaap:DeferredTaxAssetsDerivativeInstruments

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards
us-gaap:IncomeTaxAuthority
us-gaap:StatementGeographical, us-gaap:IncomeTaxAuthority
us-gaap:IncomeTaxAuthority
us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration
us-gaap:StatementGeographical, us-gaap:IncomeTaxAuthority
us-gaap:IncomeTaxAuthority, us-gaap:TaxPeriod
us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration
us-gaap:StatementGeographical, us-gaap:IncomeTaxAuthority, us-gaap:TaxPeriod

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost

us-gaap:DeferredTaxLiabilitiesDerivatives

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets

us-gaap:DeferredTaxLiabilitiesPrepaidExpenses

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment

us-gaap:DeferredTaxLiabilitiesTaxDeferredIncome
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmountsRecognizedInBalanceSheet
us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanBenefitObligation
us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanTaxStatus, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanFundedStatusOfPlan
us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsPlanAssets
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation
dei:LegalEntity, us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
dei:LegalEntity, us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanUltimateHealthCareCostTrendRate1
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation
us-gaap:DerivativeAssets
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation
us-gaap:DerivativeLiabilities
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency

us-gaap:DerivativeLiabilitiesCurrent

us-gaap:DerivativeLiabilitiesNoncurrent
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation
us-gaap:DerivativeNotionalAmount
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:DisposalGroupClassification, us-gaap:EquityMethodInvestmentNonconsolidatedInvestee, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:DisposalGroupIncludingDiscontinuedOperationConsideration
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:StatementScenario, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:AwardType
us-gaap:EmployeeRelatedLiabilitiesCurrentAndNoncurrent
us-gaap:AwardType
us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
us-gaap:Range
us-gaap:EquityMethodInvestmentOwnershipPercentage
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueLiabilitiesMeasuredOnRecurringBasisObligations
us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue

us-gaap:FinanceLeaseLiability

us-gaap:FinanceLeaseLiabilityNoncurrent

us-gaap:FinanceLeaseLiabilityPaymentsDue

us-gaap:FinanceLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount

us-gaap:FinanceLeaseRightOfUseAsset

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo

us-gaap:FiniteLivedIntangibleAssetsGross
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FundsHeldForClients

us-gaap:GoodwillGross
us-gaap:StatementBusinessSegments

us-gaap:GoodwillImpairedAccumulatedImpairmentLoss

us-gaap:IncomeTaxesReceivable

us-gaap:InsuranceSettlementsReceivableCurrent
us-gaap:LitigationStatus, us-gaap:LossContingenciesByNatureOfContingency

us-gaap:InsuranceSettlementsReceivableNoncurrent

us-gaap:InterestPayableCurrent

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:LiabilityForUncertainTaxPositionsNoncurrent

us-gaap:LitigationReserveNoncurrent

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
us-gaap:DebtInstrument
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
us-gaap:DebtInstrument, us-gaap:LongtermDebtType

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
us-gaap:DebtInstrument
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
us-gaap:DebtInstrument
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
us-gaap:DebtInstrument
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType

us-gaap:LongTermInvestmentsAndReceivablesNet
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:MarketableSecurities
us-gaap:FairValueByMeasurementFrequency
us-gaap:Ownership, us-gaap:BusinessAcquisition
us-gaap:MinorityInterestOwnershipPercentageByNoncontrollingOwners
us-gaap:Ownership, us-gaap:BusinessAcquisition
us-gaap:MinorityInterestOwnershipPercentageByParent
us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency
us-gaap:NotesAndLoansReceivableGrossNoncurrent
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:StatementScenario, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:LossContingenciesByNatureOfContingency
us-gaap:OperatingLeasesFutureMinimumPaymentsDue
us-gaap:IncomeTaxAuthority
us-gaap:OperatingLossCarryforwardsValuationAllowance
us-gaap:IncomeTaxAuthority, us-gaap:IncomeTaxAuthorityName, us-gaap:TaxCreditCarryforward

us-gaap:OtherAccruedLiabilitiesNoncurrent

us-gaap:OtherAssetsMiscellaneousNoncurrent

us-gaap:OtherDeferredCompensationArrangementsLiabilityCurrent

us-gaap:OtherEmployeeRelatedLiabilitiesCurrent

us-gaap:OtherInvestments
us-gaap:DebtInstrument
us-gaap:OtherLongTermDebtCurrent
us-gaap:DebtInstrument
us-gaap:OtherLongTermDebtNoncurrent

us-gaap:OtherSundryLiabilitiesCurrent

us-gaap:OtherSundryLiabilitiesNoncurrent
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities
us-gaap:RetirementPlanType
us-gaap:DebtInstrument
us-gaap:PledgedAssetsNotSeparatelyReportedOtherFinancialInstruments

us-gaap:RestrictedCashCurrent
us-gaap:BalanceSheetLocation, us-gaap:DebtInstrument

us-gaap:RevenueRemainingPerformanceObligation
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
us-gaap:PlanName
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
us-gaap:AwardType
us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
us-gaap:Range
us-gaap:SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleAmountOfUnrecordedBenefit

us-gaap:UnbilledReceivablesCurrent

us-gaap:UndistributedEarningsOfForeignSubsidiaries

us-gaap:UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued
us-gaap:ValuationAllowancesAndReservesType
us-gaap:ValuationAllowancesAndReservesBalance

wltw:AccruedDiscretionaryAndIncentiveCompensation

wltw:AccruedExpensesNotCurrentlyDeductible

wltw:AcquiredRenewalCommissionReceivableCurrent

wltw:AcquiredRenewalCommissionReceivableNoncurrent

wltw:AcquiredRenewalCommissionsReceivableNonCurrent

wltw:BusinessCombinationContingentConsiderationLiabilityAndDeferredConsiderationCurrent

wltw:BusinessCombinationContingentConsiderationLiabilityAndDeferredConsiderationNoncurrent

wltw:BusinessCombinationDeferredAndContingentConsideration
dei:LegalEntity
wltw:CapitalContributionObligation
us-gaap:DebtInstrument
wltw:DebtInstrumentCommitmentFeePercentage

wltw:DeferredCompensationPlanAssetsCurrent

wltw:DeferredContractCostsNoncurrent

wltw:DeferredRevenueAndAccruedLiabilitiesCurrent

wltw:DeferredTaxAssetsOperatingLeaseLiabilities

wltw:DeferredTaxLiabilitiesOperatingLeaseRightOfUseAssets

wltw:DefinedBenefitPlanExpectedFutureBenefitPayments
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
wltw:DefinedBenefitPlanFairValueOfPlanAssetsLiabilities
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
wltw:DefinedBenefitPlanFairValueOfPlanAssetsLiabilitiesNet
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

wltw:DefinedBenefitPlanFairValueOfPlanAssetsLiabilitiesReconciliation
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

wltw:DefinedBenefitPlanNetAssetsHeldInInvestments

wltw:DerivativesAndInvestmentsCurrent

wltw:FiduciaryLiabilitiesCurrent

wltw:FinanceLeaseRightOfUseAssetAccumulatedDepreciation

wltw:FinanceLeaseRightOfUseAssetGross

wltw:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFour

wltw:LeaseLiability

wltw:LeaseLiabilityCurrent

wltw:LeaseLiabilityNoncurrent

wltw:LeaseLiabilityPaymentsDue

wltw:LeaseLiabilityPaymentsDueAfterYearFive

wltw:LeaseLiabilityPaymentsDueNextTwelveMonths

wltw:LeaseLiabilityPaymentsDueYearFive

wltw:LeaseLiabilityPaymentsDueYearFour

wltw:LeaseLiabilityPaymentsDueYearThree

wltw:LeaseLiabilityPaymentsDueYearTwo

wltw:LeaseLiabilityUndiscountedExcessAmount

wltw:LeaseRightOfUseAsset
us-gaap:BusinessAcquisition
wltw:NumberOfSharesReceivableUponAcquisition

wltw:PayrollRelatedLiabilitiesCurrent

wltw:PercentageOfLeaseDenominatedInMajorCurrencies

wltw:PrepaidBonusesCurrent

wltw:PrepaidExpenseAndAccruedRevenueReceivableCurrent

wltw:PrepaidExpenseAndAccruedRevenueReceivableNoncurrent

wltw:ProvisionForLiabilitiesNonCurrent
us-gaap:ReasonablyPossibleSignificantChangeInUnrecognizedTaxBenefitsByItem, us-gaap:UnusualRiskOrUncertaintyByNature
wltw:UnrecognizedIncomeTaxExpenseRemainderOfYear

wltw:UnrecognizedTaxBenefitsIncludingInterest

Plots across concepts


IncomeStatement
Other Comprehensive Income Loss Net Of Tax
Expenses
Interest Expense
Balance Sheet
Operating Lease Right Of Use Asset
Assets
Operating Lease Right Of Use Asset
Current Assets
Other Assets Current
NonCurrent Assets
Deferred Income Tax Assets Net
PropertyPlantAndEquipmentNet
Property Plant And Equipment Net
Liabilities
Operating Lease Liability
Current Liabilities
Taxes Payable Current
Noncurrent Liabilities
Minority Interest
Stockholders Equity
Accumulated Other Comprehensive Income Loss Net Of Tax
Per Share
Common Stock Dividends Per Share Declared
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 Diluted Shares Outstanding
OperatingLeaseLiability
Operating Lease Liability Current
LesseeOperatingLeaseLiabilityPaymentsDue
Lessee Operating Lease Liability Payments Due Year Four
FiniteLivedIntangibleAssets
Finite Lived Intangible Assets Net

Tables

  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 us-gaap:SharesOutstanding us-gaap:StatementEquityComponents us-gaap:CommonStock▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁█▁▁▁▁▁▁▁▁128.988128.974128.965128.871128.763128.726128.69128.547128.983129.211128.922129.913130.73132.417132.14132.283134.613135.433136297.0137.207138.387138.39868.62567.94967.8267.79567.46NANANA67520.0NANANANANANANANANANANANANANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding ▄▄130.0130.0NA130.0130.0130.0NA130.0130.0130.0NA132.0133.0133.0NA134.0137.0138.0NA138.0140.0136.0NA182.0182.0182.0NA178.0182.0182.0NA177.0178.0176.0NA175.0176.0176.0NA176.0176.0174.0NA171.0171.0NA
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic ▄▄130.0130.0NA130.0129.0130.0NA130.0130.0130.0NA131.0132.0133.0NA134.0136.0137.0NA138.0139.0135.0NA180.0180.0179.0NA178.0179.0179.0NA177.0175.0173.0NA173.0173.0174.0NA173.0172.0171.0NA170.0170.0NA
 us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities us-gaap:RestrictedStockUnitsRSU▄▄0.20.2NANA0.00.0NA0.00.00.0NA0.30.30.0NANANANANANANANANANANANANA2.9NANANANANANANANANANANANANANANANANANA
us-gaap:EarningsPerShareBasic ▅█▇▅▅▆▇▅▅▆▆▄▄▅▅▄▄▆▅▄▅▅▄▅▄▅▄▄▄▅▄▄▅▅▁▄▅▅▄▄▄▄▅▄▅▅1.425.643.670.930.732.364.20.581.062.212.910.340.441.621.85-0.40.242.511.04-0.230.521.76-0.350.650.391.170.4299999999999997-0.040.261.370.3699999999999999-0.150.61.27-4.660.150.621.290.13999999999999990.350.490.20.58000000000000010.380.521.21
us-gaap:EarningsPerShareDiluted ▅█▇▅▅▆▇▅▅▆▆▄▄▅▅▄▄▆▅▄▅▅▄▅▄▅▄▄▄▅▄▄▅▅▁▄▅▅▄▄▄▄▅▄▅▅1.415.633.660.930.722.344.180.581.062.22.890.330.441.611.84-0.40.242.51.03-0.230.511.75-0.350.640.381.150.42999999999999994-0.040.261.350.3700000000000001-0.150.591.24-4.620.150.611.280.13999999999999990.340.480.20.57000000000000030.370.521.2
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 TTM Greenblatt ROC _ _▆▇█▅▅▆█▅▆▆▇▅▅▆▅▅▅▇▅▅▅▆▅▅▅▆▅▅▅▆▅▅▆▆▁▅▆▆▅▅▅▆▆260.0452.0587.073.0163.0360.0687.0107.0176.0359.0470.017.063.0259.0110.041.0124.0463.088.01.0136.0326.02.027.0105.0293.0139.034.0148.0326.0152.075.0171.0287.0-775.070.0179.0317.081.090.0157.0238.0177.0NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:ComprehensiveIncomeNetOfTax ▆█▆▆▅▅▇▅▅▆▅▅▄▆▆▅▅▆▃▅▅▆▄▅▅▆▄▄▅▆▆▅▅▆▁▅▅▆▄▅▅▅▅▅▅217.0781.0370.0258.0150.086.0430.0-45.0119.0310.044.022.0-117.0298.0408.046.0165.0320.0-521.0-72.0-56.0222.0-107.035.0150.0324.0-255.0-82.072.0254.0183.045.0111.0183.0-938.053.077.0256.0-180.09.0106.066.0129.0102.073.0NA
us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest ▄▄▅▄▅▅▅▄▆▄▄▄▅▅█▁▇▆▃▄▅▂▄▂▅▃▄▃▄▄▅▄▄▄▄▃▄▅▄▃▄▅▄▄▄2.05.08.02.08.07.08.03.013.05.05.02.06.07.022.0-12.016.011.00.01.06.0-9.03.0-5.06.0-3.02.0-2.01.04.06.01.02.03.04.00.01.08.03.0-2.04.09.03.01.02.0NA
us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest ▆█▆▆▅▅▇▅▅▆▅▅▄▆▇▅▆▆▃▅▅▆▄▅▅▆▄▄▅▆▆▅▅▆▁▅▅▆▄▅▅▅▅▅▅219.0786.0378.0260.0158.093.0438.0-42.0132.0315.049.024.0-111.0305.0430.034.0181.0331.0-525.0-73.0-62.0231.0-104.030.0156.0321.0-253.0-84.073.0258.0189.046.0113.0186.0-934.053.078.0264.0-177.09.0110.075.0132.0103.075.0NA
us-gaap:CostsAndExpenses ▅▇█▃▃▇▄▂▂▃▂▁▃▅2026.02138.02177.01936.01950.02106.02003.01882.01872.01953.01902.01842.01927.02033.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:DisposalGroupNotDiscontinuedOperationGainLossOnDisposal ▁█▁▃▁-2.0359.0-2.085.0-2.0NANANANANANANANANANANANANANANANANA0.014.07.04.013.00.02.0-3.02.00.00.00.0NA1.0NANANANANANANANANANA
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest ▄█▆▃▃▄▇▂▃▄▅▂▂▃▂▁282.0832.0602.0168.0177.0391.0675.0100.0187.0360.0477.036.074.0264.080.0-35.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:IncomeTaxExpenseBenefit ▇▇█▆▇▇█▆▆▇▇▅▅▆▁▆▅▆▃▄▆▆▅▂▆▆▆▅▆▇▆▅▆▆▅▅▆▇▅▅▆▅▆▅▆▇96.096.0119.046.075.078.0124.020.038.067.094.0-10.09.043.0-173.019.08.046.0-107.0-26.019.018.04.0-112.019.056.035.02.059.063.034.011.029.048.0-13.010.036.068.0-2.02.031.01.028.010.035.067.0
us-gaap:InterestExpense ▆▇██████▇▆▆▆▆▆▅▅▄▄▄▄▅▄▃▂▂▂▂▂▂▁▂▁▁▁▁▁▂▁▄▃▂▃▄▃▃▄52.059.060.061.062.061.062.062.056.054.054.051.052.051.049.047.046.046.046.045.047.046.039.035.035.033.034.034.035.032.033.030.032.031.031.032.033.032.044.038.034.040.042.040.041.043.0
us-gaap:NetIncomeLoss ▆█▇▅▅▆▇▅▅▆▆▅▅▆▆▄▅▆▅▅▅▆▅▅▅▆▅▅▅▆▅▅▅▆▁▅▅▆▅▅▅▅▅▅▅▆184.0733.0476.0121.094.0305.0544.075.0138.0287.0378.044.058.0215.0245.0-54.033.0344.0142.0-32.072.0238.0-24.0117.070.0210.076.0-7.047.0246.068.0-27.0105.0219.0-805.026.0108.0225.025.060.085.034.098.064.089.0204.0
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest ▃▃▆▂▆▆▆▄█▅▄▃▆▅▆▂▆▆▅▂▄▆▅▁▃▄▆▁▂▄▅▂▃▄▄▂▃▆▄▂▄▆▄▂▃▆2.03.07.01.08.08.07.05.011.06.05.02.07.06.08.00.08.08.06.01.04.07.06.0-1.02.04.07.0-1.01.04.06.00.02.04.04.00.02.07.04.00.04.08.05.01.02.07.0
us-gaap:OperatingIncomeLoss ▆▇█▅▅▆█▅▆▆▇▅▅▆▅▅▅▇▅▅▅▆▅▅▅▆▅▅▅▆▅▅▆▆▁▅▆▆▅▅▅▆▆▅▆▆260.0452.0587.073.0163.0360.0687.0107.0176.0359.0470.017.063.0259.0110.041.0124.0463.088.01.0136.0326.02.027.0105.0293.0139.034.0148.0326.0152.075.0171.0287.0-775.070.0179.0317.081.090.0157.0238.0177.0106.0169.0301.0
us-gaap:OtherComprehensiveIncomeLossNetOfTax ▁█33.050.0NANA56.0-220.0NANA-17.022.0NA-22.0-176.084.0177.088.0140.0-21.0-673.0-42.0-138.0-14.0-86.0-86.084.0107.0-336.0-76.025.08.0115.073.06.0-37.0-133.027.0-32.032.0NANANANANANANANA
us-gaap:OtherNonoperatingIncomeExpense ▃█▃▄▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁▁▂▁▂▂▂▁▂▁▁▁▂▂▂▂74.0439.075.0156.076.092.050.055.067.055.061.070.063.056.018.0-29.0-30.0-20.0-1.0-14.06.0-18.029.09.023.0-6.018.0-9.0-3.00.07.05.04.06.0NANANANANANANANANANANANA
us-gaap:ProfitLoss ▅█▇▅▅▆▇▅▅▆▆▅▅▆▆▄▅▆▅▅▅▆▅▅▅▆▅▅▅▆▅▅▅▆▁▅▅▆▅▅▅▅▅▅▅▆186.0736.0483.0122.0102.0313.0551.080.0149.0293.0383.046.065.0221.0253.0-54.041.0352.0148.0-31.076.0245.0-18.0116.072.0214.083.0-8.048.0250.074.0-27.0107.0223.0-801.026.0110.0232.029.060.089.042.0103.065.091.0211.0
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax ▆▇█▅▆▇█▅▅▆▇▅▅▆▆▅▅▆▅▅▅▆▂▁▂▂▂▁▂▂▂▁▂▂▁▁▁▂▁▁▁▂▁▁▁▂2245.02562.02752.01999.02101.02434.02690.01966.02030.02286.02372.01826.01966.02274.02078.01852.01953.02319.01927.01777.01949.02234.0974.0846.0922.01087.0958.0812.0935.01097.0919.0795.0890.01051.0871.0754.0842.01013.0819.0762.0863.01008.0833.0733.0799.0972.0
us-gaap:Revenues ▆▇█▅▆▇█▅▆▆▇▅▅▆▆▅▅▆▅▅▅▆▂▁▂▂▂▁▂▂▂▁▂▂▁▁▁▂▁▁▁▂▁▁▁▂2286.02590.02764.02009.02113.02466.02690.01989.02048.02312.02372.01859.01990.02292.02078.01852.01953.02319.01927.01777.01949.02234.0974.0846.0922.01087.0958.0812.0935.01097.0919.0795.0890.01051.0871.0754.0842.01013.0819.0762.0863.01008.0833.0733.0799.0972.0
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:Assets ██████▇▇▇▇▆▆▇▇▆▆▆▆▆▆▆▆▂▂▂▁▁▁▂▁▁▁▁▁▁▂▂▂▁▂▂▂▁38267.038632.038531.038037.038110.037727.035426.035703.035166.035893.032385.033041.034213.034212.032458.032272.032774.032232.030253.031801.032409.033029.018839.017813.018319.016105.015435.015208.016551.015828.014800.015323.015938.015802.015112.017003.017608.017091.015728.016615.017941.017238.015847.0NANANA
us-gaap:Liabilities ▇█████▇▇▇▇▆▆▆▆▅▅▆▅▄▅▅▅▃▂▂▂▁▁▂▁▁▁▂▂▁▂▂▂▁▂▂▂▁26552.027058.027599.027417.027654.027338.025057.025672.024934.025651.022388.022851.023839.023382.022181.022191.022330.021775.020019.020847.021169.021672.016426.015275.015778.013733.013369.012935.014089.013356.012557.013276.013938.013909.013387.014305.014897.014387.013211.013898.015202.014569.013239.0NANANA
us-gaap:LiabilitiesAndStockholdersEquity ██████▇▇▇▇▆▆▇▇▆▆▆▆▆▆▆▆▂▂▂▁▁▁▂▁▁▁▁▁▁▂▂▂▁▂▂▂▁38267.038632.038531.038037.038110.037727.035426.035703.035166.035893.032385.033041.034213.034212.032458.032272.032774.032232.030253.031801.032409.033029.018839.017813.018319.016105.015435.015208.016551.015828.014800.015323.015938.015802.015112.017003.017608.017091.015728.016615.017941.017238.015847.0NANANA
us-gaap:StockholdersEquity ██▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇██▁▁▁▁▁▁▂▂▁▁▁▁▁▂▂▂▂▂▂▂▂11670.011526.010820.010515.010335.010263.010249.09887.010090.010092.09852.010049.010228.010672.010126.09915.010263.010278.010065.010767.011050.011151.02229.02393.02393.02298.01985.02258.02444.02442.02215.02024.01977.01865.01699.02674.02687.02675.02486.02688.02707.02630.02577.0NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:AssetsCurrent ███▇▇▇▅▆▆▇▅▅▆▆▅▅▅▅▃▄▄▄▂▂▃▂▁▁▂▂▁▁▂▂▁▂▃▂▁▂▃▂▁20568.020872.020301.019914.019922.019550.017037.017400.018333.019020.016420.016756.017889.017606.015861.015691.016233.015795.013792.014733.015230.015579.012503.012334.012946.011328.010853.010824.012072.011445.010461.011014.011674.011595.010898.012116.012726.012217.010987.011700.012981.012304.011100.0NANANA
 us-gaap:Cash dei:LegalEntity,us-gaap:Range wltw:WillisLimited,srt:MinimumNANA51.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:CashAndCashEquivalentsAtCarryingValue █▇█▆▄▄▃▃▃▄▄▄▄▄▄▄▃▄▃▃▄▄▂▂▂▂▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▁▁▁2217.01960.02089.01647.01087.0898.0887.0867.0812.0992.01033.0931.0911.0954.01030.0912.0852.0901.0870.0767.0949.0954.0532.0466.0483.0503.0635.0656.0708.0734.0796.0623.0503.0531.0500.0424.0407.0464.0436.0363.0317.0432.0316.0159.0167.0222.0
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents █▇▇▅▂▁▁▁▁▂▂▂2221.01966.02096.01654.01094.0906.0895.0874.0812.0992.01033.0931.0NANA1030.0NANANA870.0NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:AccountsReceivableNetCurrent ███▆▇██▆▇▇▇▆▇█▇▆▇▇▆▆▆▇▃▂▃▂▂▂▂▂▂▂▂▂▁▁▂▂▁▁▂▂▁2507.02569.02555.02223.02430.02594.02621.02167.02461.02490.02379.02132.02394.02600.02246.02155.02288.02307.02080.02043.02187.02268.01258.01100.01226.01150.01044.01021.01175.01185.01041.0985.01044.01051.0933.0908.01022.01009.0910.0911.01049.0992.0839.0NANANA
us-gaap:OtherAssetsCurrent NA53.075.0NA47.0100.0112.089.081.0NA57.068.0NANA71.067.0NANA55.0NANA49.0255.0240.0222.0218.0214.0229.0195.0204.0197.0195.0207.0186.0181.0317.0309.0325.0259.0315.0327.0369.0340.0NANANA
us-gaap:PrepaidExpenseAndOtherAssetsCurrent ▅▅▆▆▃▆▇█▅▄▄▇▅▅▅▄▃▂▃▂▃▂▁465.0432.0497.0484.0363.0469.0525.0587.0451.0409.0404.0547.0458.0439.0430.0418.0342.0321.0337.0319.0327.0326.0255.0NANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NoncurrentAssets NANA18135.0NANANA18317.0NANANA15906.0NANANA16551.0NANANA16411.0NANANA6260.0NANANA4563.0NANANANANANANANANANANANANANANANANANANA
 us-gaap:NoncurrentAssets us-gaap:StatementGeographical country:GBNANA2840.0NANANA2901.0NANANA2349.0NANANA3173.0NANANA2431.0NANANA2426.0NANANA1666.0NANANA233.0NANANA218.0NANANANANANANANANANANA
 us-gaap:NoncurrentAssets us-gaap:StatementGeographical country:IENANA110.0NANANA103.0NANANA78.0NANANA127.0NANANA114.0NANANA124.0NANANA121.0NANANANANANANANANANANANANANANANANANANA
 us-gaap:NoncurrentAssets us-gaap:StatementGeographical country:USNANA12652.0NANANA12786.0NANANA11068.0NANANA9988.0NANANA11400.0NANANA1759.0NANANA1800.0NANANA203.0NANANA207.0NANANANANANANANANANANA
 us-gaap:NoncurrentAssets us-gaap:StatementGeographical wltw:ForeignCountriesNANA18025.0NANANA18214.0NANANA15828.0NANANA16424.0NANANA16297.0NANANA6136.0NANANA4442.0NANANANANANANANANANANANANANANANANANANA
 us-gaap:NoncurrentAssets us-gaap:StatementGeographical wltw:RestOfWorldNANA2533.0NANANA2527.0NANANA2411.0NANANA3263.0NANANA2466.0NANANA1951.0NANANA976.0NANANANANANANANANANANANANANANANANANANA
us-gaap:AssetsNoncurrent ████████▇▇▇▇▇▇▇▇▇▇▇▇▇█▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁17699.017760.018230.018123.018188.018177.018389.018303.016833.016873.015965.016285.016324.016606.016597.016581.016541.016437.016461.017068.017179.017450.06336.05479.05373.04777.04582.04384.04479.04383.04339.04309.04264.04207.04214.04887.04882.04874.04741.04915.04960.04934.04747.0NANANA
us-gaap:PropertyPlantAndEquipmentGross NANA2141.0NANANA1942.0NANANA1710.0NANANA1862.0NANANA1481.0NANANA1091.0NANANA980.0NANANA949.0NANANA881.0NANANA792.0NANANA753.0NANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:FurnitureAndFixturesNANA1473.0NANANA1302.0NANANA1130.0NANANA1300.0NANANA1009.0NANANA724.0NANANA642.0NANANA618.0NANANA576.0NANANA509.0NANANA488.0NANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:LandAndBuildingNANA90.0NANANA90.0NANANA92.0NANANA94.0NANANA90.0NANANA95.0NANANA93.0NANANA89.0NANANA78.0NANANA73.0NANANA73.0NANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType us-gaap:LeaseholdImprovementsNANA578.0NANANA550.0NANANA488.0NANANA468.0NANANA382.0NANANA272.0NANANA245.0NANANA242.0NANANA227.0NANANA210.0NANANA192.0NANANA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment NANA1127.0NANANA896.0NANANA768.0NANANA877.0NANANA642.0NANANA528.0NANANA497.0NANANA468.0NANANA413.0NANANA386.0NANANA372.0NANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType us-gaap:FurnitureAndFixturesNANA769.0NANANA594.0NANANA519.0NANANA652.0NANANA464.0NANANA393.0NANANA366.0NANANA345.0NANANA306.0NANANA297.0NANANA291.0NANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType us-gaap:LandAndBuildingNANA62.0NANANA57.0NANANA52.0NANANA49.0NANANA41.0NANANA41.0NANANA38.0NANANA36.0NANANA32.0NANANA28.0NANANA25.0NANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType us-gaap:LeaseholdImprovementsNANA296.0NANANA245.0NANANA197.0NANANA176.0NANANA137.0NANANA94.0NANANA93.0NANANA87.0NANANA75.0NANANA61.0NANANA56.0NANANA
us-gaap:AmortizationOfIntangibleAssets ▅▅▆▆▆▆▆▆▆▆▆▆▇▇▇▇▇█▇█▆█▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁98.0103.0114.0108.0119.0121.0121.0118.0123.0127.0126.0127.0140.0141.0140.0141.0149.0151.0148.0157.0125.0161.023.023.016.014.016.013.012.013.013.014.014.014.015.014.015.015.0NANANANANANANANA
us-gaap:PropertyPlantAndEquipmentNet ▇▇█▇▇▇█▇▇▇▇▇▇▇▇▇▆▆▆▆▅▅▃▃▂▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁927.0951.01014.0997.0989.0974.01046.0963.0967.0957.0942.0944.0924.0926.0985.0937.0895.0863.0839.0811.0794.0790.0563.0531.0516.0462.0483.0481.0496.0482.0481.0472.0452.0447.0468.0446.0428.0426.0406.0387.0391.0386.0381.0NANANA
us-gaap:Goodwill ████████▇▇▇▇▇▇▇▇▇▇▇▇▇▇▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁10995.010986.011204.011131.011196.011162.011194.011187.010454.010456.010465.010457.010468.010555.010519.010529.010509.010442.010413.010483.010527.010477.03737.03150.03097.02889.02937.02803.02870.02835.02838.02846.02829.02813.02827.03304.03298.03308.03295.03297.03317.03312.03294.0NANANA
us-gaap:IntangibleAssetsNetExcludingGoodwill ▄▄▄▅▅▅▅▅▄▅▅▅▅▆▆▆▆▇▇▇▇█▁2786.02878.03043.03125.03257.03360.03478.03561.03055.03187.03318.03429.03562.03761.03882.04034.04156.04245.04368.04589.04713.05086.01115.0NANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:FiniteLivedIntangibleAssetsNet ▅▅▅▅▅▆▆▆▅▅▅▆▆▆▆▇▇▇▇▇▇█▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁2786.02878.03043.03125.03257.03360.03478.03561.03055.03187.03318.03429.03562.03761.03882.04034.04156.04245.04332.04553.04649.04995.01115.0665.0675.0418.0450.0331.0360.0339.0353.0361.0373.0369.0385.0379.0391.0406.0420.0440.0461.0477.0492.0NANANA
us-gaap:OperatingLeaseRightOfUseAsset ▇▇█▇▇█████▁830.0841.0902.0894.0894.0906.0968.0959.0930.0946.00.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsNoncurrent ███▇▆▆▆▅▄▃▃▃▃▄▃▃▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▂▂▂▂▂▂▂▁1135.01113.01096.0935.0877.0860.0835.0701.0541.0494.0467.0500.0468.0532.0447.0432.0386.0351.0353.0328.0330.0348.0209.0211.0234.0229.0220.0196.0194.0209.0206.0187.0205.0199.0206.0328.0360.0353.0283.0339.0365.0357.0233.0NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:DividendsPayableCurrent 19.0NA103.0NANANA100.0NANANA87.0NANANANANANANANANANANANA58.065.058.055.054.055.055.051.050.050.048.047.048.047.049.046.045.046.0NA46.0NANANA
us-gaap:LiabilitiesCurrent █████▇▆▆▆▇▅▅▆▅▅▅▅▅▄▄▅▅▃▃▃▂▂▁▂▂▁▁▂▂▂▂▃▂▁▂▃▂▂19174.019020.019332.019220.019019.018624.016070.016736.017204.017654.015301.015555.016382.015804.014755.014556.015029.014585.013370.014217.014417.015256.012801.011881.012495.010548.010232.010005.010984.010276.09474.010135.010765.010671.010194.011086.011649.011091.09996.010820.012083.011358.010309.0NANANA
us-gaap:LongTermDebtCurrent █▃▇▇▄▅▂▃▁▁▁1110.0471.0971.0973.0525.0697.0316.0484.0187.0187.0186.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OperatingLeaseLiabilityCurrent ▇▇▇▇▇▇█▇██▁152.0147.0152.0143.0144.0151.0164.0151.0154.0158.00.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherLiabilitiesCurrent ▆█▇▆▆▇▆▆▆▇▇▆▆▇▆▆▇█▇▆▇█▄▃▃▃▃▃▃▃▂▂▂▂▂▁▁▂▁▁▁▂▁751.0965.0888.0811.0804.0858.0802.0801.0810.0940.0864.0758.0814.0867.0804.0793.0882.0996.0876.0812.0901.0972.0558.0488.0522.0461.0444.0445.0467.0495.0415.0381.0358.0333.0327.0289.0297.0334.0282.0274.0318.0343.0266.0NANANA
us-gaap:TaxesPayableCurrent 116.0NA102.0NANANA138.0165.0NANA129.0NANANA90.0NANA179.091.079.0129.0136.045.0NANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:LiabilitiesNoncurrent ▆▇▇▇████▇▇▆▆▆▆▆▆▆▆▅▅▅▅▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁7378.08038.08267.08197.08635.08714.08987.08936.07730.07997.07087.07296.07457.07578.07426.07635.07301.07190.06649.06630.06752.06416.03625.03394.03283.03185.03137.02930.03105.03080.03083.03141.03173.03238.03193.03219.03248.03296.03215.03078.03119.03211.02930.0NANANA
us-gaap:LongTermDebt NANA7884.0NANANA8017.0NANANA6400.0NANANA5638.0NANANA4943.0NANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument wltw:CollateralizedFacilityNANA55.0NANANA79.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType wltw:InterestOnSeniorNotes,us-gaap:SeniorNotesNANA2219.0NANANA2362.0NANANA1791.0NANANA1078.0NANANA1049.0NANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LongtermDebtType us-gaap:SeniorNotesNANA5610.0NANANA5281.0NANANA4479.0NANANA3506.0NANANA3176.0NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LongTermDebtNoncurrent ▅▆▆▆▇███▆▆▆▆▆▆▆▆▅▅▄▄▄▃▁▁▁▁▁▁▂▂▂▂▂▂▂▂▂▂▂▁▂▂▁3995.04632.04664.04641.05068.05177.05301.05381.04284.04518.04389.04498.04589.04507.04450.04493.04097.03975.03357.03267.03281.02767.02278.02248.02052.02137.02142.02148.02302.02307.02311.02315.02326.02387.02338.02364.02397.02435.02354.02285.02307.02432.02157.0NANANA
us-gaap:DeferredIncomeTaxLiabilitiesNet ▆▄▃▄▄▁▂█628.0576.0561.0587.0575.0501.0526.0690.0NANA559.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent ▇▇█▇▇▇▇▆▆▆▇▆▇▇▇▇▇▇▇▆▆▇▁1238.01278.01405.01172.01235.01261.01324.01039.01125.01135.01170.01087.01185.01230.01259.01207.01271.01286.01321.01089.01160.01210.0279.0NANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:MinorityInterest ▃▃▆▆▆▇▆▆▆▆▆▆▆▇▆▆▇▇▆▇▇█▇▅▅▁▁▁▁▂▂▁▁▂▂▁▁▂▂▂▂▂▂45.048.0112.0105.0121.0126.0120.0114.0114.0122.0119.0114.0119.0130.0123.0111.0124.0126.0118.0134.0138.0153.0131.093.096.023.022.015.018.030.028.023.023.028.026.024.024.029.031.029.032.039.031.0NANANA
us-gaap:OtherLiabilitiesNoncurrent ▁▂▂▂▂▂▂▂▁▁▄▅▅▆▇▅▅▆▆▇▇█▆▆▆▄▃▂▃▃▃▃▃▃▃▃▃▃▃▃▃▃▂280.0305.0312.0322.0317.0320.0335.0314.0299.0296.0429.0448.0446.0506.0544.0476.0473.0512.0532.0544.0561.0605.0533.0502.0506.0398.0389.0347.0362.0354.0374.0353.0371.0378.0375.0376.0381.0371.0363.0362.0367.0371.0347.0NANANA
us-gaap:OperatingLeaseLiabilityNoncurrent ▇▇████████▁838.0857.0918.0915.0906.0914.0964.0957.0941.0961.00.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo NANA172.0NANANANA182.0178.0180.0180.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree NANA157.0NANANANA162.0161.0160.0159.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour NANA138.0NANANANA147.0144.0142.0142.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive NANA123.0NANANANA137.0134.0132.0131.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive NANA458.0NANANANA624.0572.0552.0542.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:StockholdersEquity ██▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇██▁▁▁▁▁▁▂▂▁▁▁▁▁▂▂▂▂▂▂▂▂11670.011526.010820.010515.010335.010263.010249.09887.010090.010092.09852.010049.010228.010672.010126.09915.010263.010278.010065.010767.011050.011151.02229.02393.02393.02298.01985.02258.02444.02442.02215.02024.01977.01865.01699.02674.02687.02675.02486.02688.02707.02630.02577.0NANANA
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest ██▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇██▁▂▂▁▁▁▂▂▁▁▁▁▁▂▂▂▂▂▂▂▂▂▁11715.011574.010932.010620.010456.010389.010369.010001.010204.010214.09971.010163.010347.010802.010249.010026.010387.010404.010183.010901.011188.011304.02360.02486.02489.02321.02007.02273.02462.02472.02243.02047.02000.01893.01725.02698.02711.02704.02517.02717.02739.02669.02608.02498.02429.0NA
us-gaap:AdditionalPaidInCapitalCommonStock █▇▇▆▆▅▅▄▃▃▂▁10785.010765.010748.010724.010713.010703.010687.010667.010644.010630.010615.010577.0NANA10538.0NANANANANANANA1672.01673.01650.01584.01524.01475.01443.01378.01316.01258.01207.01155.01125.01116.01091.01072.01073.01050.01033.01017.0985.0NANANA
us-gaap:RetainedEarningsAccumulatedDeficit ██▆▄▄▄▃▂▂▂▁▁▂▃▁▁▂▃▂▂▃▃▃▃▃▃▂▂▃▃▃▃▃▃▂▅▅▅▅▅▅▄▅3166.03075.02434.02047.02015.02009.01792.01336.01442.01439.01201.01102.01270.01557.01104.01130.01402.01561.01452.01455.01739.01771.01597.01677.01618.01669.01530.01521.01664.01752.01595.01577.01653.01599.01427.02278.02343.02319.02160.02180.02165.02125.02136.0NANANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▂▂▁▂▁▁▂▂▃▃▃▄▄▅▅▄▄▃▃▆▆▆▇▇▇▇▆████-2278.0-2311.0-2359.0-2253.0-2390.0-2446.0-2227.0-2113.0-1993.0-1974.0-1961.0-1627.0-1605.0-1430.0-1513.0-1676.0-1776.0-1908.0-1884.0-1221.0-1181.0-1053.0-1037.0-954.0-872.0-952.0-1066.0-735.0-660.0-685.0-693.0NANANA-853.0-720.0-747.0-715.0-744.0-539.0-488.0-509.0-541.0NANANA
us-gaap:TreasuryStockValue ▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▄▂▁█▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁3.03.03.03.03.03.03.03.03.03.03.03.03.03.03.040.021.03.099.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.0NANANA
us-gaap:MinorityInterest ▃▃▆▆▆▇▆▆▆▆▆▆▆▇▆▆▇▇▆▇▇█▇▅▅▁▁▁▁▂▂▁▁▂▂▁▁▂▂▂▂▂▂45.048.0112.0105.0121.0126.0120.0114.0114.0122.0119.0114.0119.0130.0123.0111.0124.0126.0118.0134.0138.0153.0131.093.096.023.022.015.018.030.028.023.023.028.026.024.024.029.031.029.032.039.031.0NANANA
us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders ▁█4.017.0NA9.012.01.0NA1.019.0NANA6.016.0NANANANANANANANANANANANANANA1.0NANANA1.0NANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▇▁▇▇█▂▆▅▅▂▇▅▅▂▅▄▅▃▅▄▅▃▃▃▃▂▄▃▃▂▄▄▃▂▄▃▃▃▄▃▃▂▄▃▃▃494.0-128.0568.0521.0662.023.0461.0317.0350.0-47.0572.0321.0377.018.0347.0196.0319.095.0312.0181.0309.0118.0130.0106.071.0-64.0196.0129.0147.05.0195.0229.098.039.0215.0152.096.062.0167.0146.0119.07.0241.094.085.069.0
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆█▆▆▅▅▅▁▆▆▅▅▆▆▆▅▅▅▅▆▅▇▄▅▅▆▅▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆-55.0645.0-52.0141.0-87.0-162.0-83.0-1383.0-73.0-75.0-101.0-87.0-74.0-79.0-73.0-107.0-155.0-82.0-88.0-25.0-109.0417.0-595.0-100.0-240.0-8.0-159.0-35.0-61.0-21.0-15.0-30.0-54.0-21.0-73.0-33.0-29.0-37.0-29.0-20.0-28.0-24.0-18.0-19.0-16.0-41.0
us-gaap:NetCashProvidedByUsedInFinancingActivities ▃▁▃▃▂▄▂█▂▄▂▃▂▃▃▃▃▄▃▂▃▃▆▃▄▃▃▃▃▃▃▃▃▄▃▃▃▃▃▃▃▄▃▃▃▃-188.0-633.0-100.0-119.0-401.0186.0-377.01148.0-456.082.0-361.0-207.0-311.0-24.0-233.0-50.0-196.014.0-116.0-331.0-200.0-115.0547.0-10.0143.0-39.0-40.0-128.0-106.0-49.0-5.0-82.0-68.018.0-67.0-104.0-120.00.0-64.0-69.0-208.0127.0-67.0-89.0-120.0-17.0
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:DeferredIncomeTaxExpenseBenefit █▇█▇█▆▆▆▆▆▅▆▆▆▁▇▆▅▄▅▇▅▆▄▇▇46.010.044.015.063.0-23.0-28.0-3.0-13.0-28.0-45.0-22.0-22.0-26.0-229.018.00.0-74.0-124.0-64.014.0-70.0-28.0-104.021.012.0NANANANANANANANANANANANANANANANANANANANA
us-gaap:IncreaseDecreaseInAccountsReceivable ▃▅▆▁▂▄█▁▃▅▆▁▂▄▅▂▃▆▅▂▃▅▅▃▄▅▄▃▄▅▄▃▄▅▄▂▄▄▄▃▄▅▄▃▄▄-76.0115.0287.0-231.0-174.046.0454.0-275.0-39.0121.0264.0-251.0-124.043.095.0-205.0-79.0253.0121.0-143.0-38.0161.0100.0-105.08.0152.035.0-106.0-3.0140.060.0-68.0-4.0128.025.0-119.031.080.012.0-108.049.0139.0-8.0-76.042.077.0
us-gaap:NetCashProvidedByUsedInOperatingActivities ▇▁▇▇█▂▆▅▅▂▇▅▅▂▅▄▅▃▅▄▅▃▃▃▃▂▄▃▃▂▄▄▃▂▄▃▃▃▄▃▃▂▄▃▃▃494.0-128.0568.0521.0662.023.0461.0317.0350.0-47.0572.0321.0377.018.0347.0196.0319.095.0312.0181.0309.0118.0130.0106.071.0-64.0196.0129.0147.05.0195.0229.098.039.0215.0152.096.062.0167.0146.0119.07.0241.094.085.069.0
us-gaap:NetIncomeLoss ▆█▇▅▅▆▇▅▅▆▆▅▅▆▆▄▅▆▅▅▅▆▅▅▅▆▅▅▅▆▅▅▅▆▁▅▅▆▅▅▅▅▅▅▅▆184.0733.0476.0121.094.0305.0544.075.0138.0287.0378.044.058.0215.0245.0-54.033.0344.0142.0-32.072.0238.0-24.0117.070.0210.076.0-7.047.0246.068.0-27.0105.0219.0-805.026.0108.0225.025.060.085.034.098.064.089.0204.0
us-gaap:ProfitLoss ▅█▇▅▅▆▇▅▅▆▆▅▅▆▆▄▅▆▅▅▅▆▅▅▅▆▅▅▅▆▅▅▅▆▁▅▅▆▅▅▅▅▅▅▅▆186.0736.0483.0122.0102.0313.0551.080.0149.0293.0383.046.065.0221.0253.0-54.041.0352.0148.0-31.076.0245.0-18.0116.072.0214.083.0-8.048.0250.074.0-27.0107.0223.0-801.026.0110.0232.029.060.089.042.0103.065.091.0211.0
us-gaap:ShareBasedCompensation ▆▆▇▇▇▁▆▅▄▃█▃▁▂▅▄▅▄▇▆██▅▄▄▅▃▄▄▄▃▃▃▄▃▃▃▃▃▃▃▄▄▃▄▄25.027.031.031.029.0-1.026.021.017.010.035.011.01.03.019.015.019.014.029.026.033.035.018.012.016.018.010.014.014.014.011.010.09.012.08.07.08.09.08.09.010.014.013.09.013.012.0
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆█▆▆▅▅▅▁▆▆▅▅▆▆▆▅▅▅▅▆▅▇▄▅▅▆▅▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆-55.0645.0-52.0141.0-87.0-162.0-83.0-1383.0-73.0-75.0-101.0-87.0-74.0-79.0-73.0-107.0-155.0-82.0-88.0-25.0-109.0417.0-595.0-100.0-240.0-8.0-159.0-35.0-61.0-21.0-15.0-30.0-54.0-21.0-73.0-33.0-29.0-37.0-29.0-20.0-28.0-24.0-18.0-19.0-16.0-41.0
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▃▁▃▃▂▄▂█▂▄▂▃▂▃▃▃▃▄▃▂▃▃▆▃▄▃▃▃▃▃▃▃▃▄▃▃▃▃▃▃▃▄▃▃▃▃-188.0-633.0-100.0-119.0-401.0186.0-377.01148.0-456.082.0-361.0-207.0-311.0-24.0-233.0-50.0-196.014.0-116.0-331.0-200.0-115.0547.0-10.0143.0-39.0-40.0-128.0-106.0-49.0-5.0-82.0-68.018.0-67.0-104.0-120.00.0-64.0-69.0-208.0127.0-67.0-89.0-120.0-17.0
us-gaap:RepaymentsOfLongTermDebt ▁▄▁▁▂▂▂▆▁▁▁▂▁▁▁▁▅▅▁▁▅█▁▂▁▁7.0508.08.08.0183.0128.0170.0822.02.01.00.0127.022.021.020.019.0695.0636.040.035.0645.01181.07.0151.04.04.0NANANANANANANANANANANANANANANANANANANANA
us-gaap:PaymentsOfDividendsCommonStock █▅▄▄▄▄▄▄▄▄▄▄▄▄▄▄▆▄▄▄▄▁▅▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃177.092.087.088.087.084.084.084.084.077.078.079.081.068.068.072.0137.065.066.066.067.00.0112.056.055.054.053.054.053.050.049.049.048.047.046.046.047.046.044.046.045.045.044.043.045.044.0
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31

Shares Outstanding

us-gaap:SharesOutstanding us-gaap:StatementEquityComponents

us-gaap:SharesOutstanding

us-gaap:CommonStock


Shares
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value128128128128128128128128128129128129130132132132134135136297137138138686767676767520
Percentage of SharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value130130130130130130130130132133133134137138138140136182182182178182182177178176175176176176176174171171
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
Value130130130129130130130130131132133134136137138139135180180179178179179177175173173173174173172171170170
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

us-gaap:RestrictedStockUnitsRSU


Antidilutive
Period End2021-06-302021-03-312020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312014-09-30
Value0.20.20.00.00.00.00.00.30.30.02.9
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.0100.00.00.00.00.00.0100.0100.00.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.425.643.670.930.732.364.20.581.062.212.910.340.441.621.85-0.40.242.511.04-0.230.521.76-0.350.650.391.170.43-0.040.261.370.37-0.150.61.27-4.660.150.621.290.140.350.490.20.580.380.521.21
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareDiluted


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.415.633.660.930.722.344.180.581.062.22.890.330.441.611.84-0.40.242.51.03-0.230.511.75-0.350.640.381.150.43-0.040.261.350.37-0.150.591.24-4.620.150.611.280.140.340.480.20.570.370.521.2
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value21778137025815086430-45.01193104422-117.029840846165320-521.0-72.0-56.0222-107.035150324-255.0-82.07225418345111183-938.05377256-180.09.01066612910273
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.730.50.012.97.13.516.0-2.35.913.61.91.2-6.013.119.62.58.413.8-27.0-4.1-2.99.9-11.04.116.329.8-26.6-10.17.723.219.95.712.517.4-107.77.09.125.3-22.01.212.36.515.513.99.1

Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value2.05.08.02.08.07.08.03.0135.05.02.06.07.022-12.016110.01.06.0-9.03.0-5.06.0-3.02.0-2.01.04.06.01.02.03.04.00.01.08.03.0-2.04.09.03.01.02.0
Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.00.10.40.30.30.20.60.20.20.10.30.31.1-0.60.80.50.00.10.3-0.40.3-0.60.7-0.30.2-0.20.10.40.70.10.20.30.50.00.10.80.4-0.30.50.90.40.10.3

Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value21978637826015893438-42.01323154924-111.030543034181331-525.0-73.0-62.0231-104.030156321-253.0-84.07325818946113186-934.05378264-177.09.01107513210375
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.830.70.013.07.53.816.3-2.16.513.82.11.3-5.613.420.71.89.314.3-27.2-4.1-3.210.3-10.73.516.929.5-26.4-10.37.823.520.65.812.717.7-107.27.09.326.1-21.61.212.77.415.814.19.4

Costs And Expenses

us-gaap:CostsAndExpenses

us-gaap:CostsAndExpenses


Costs
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value20262138217719361950210620031882187219531902184219272033
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax90.283.50.096.892.886.574.595.792.285.480.2100.998.089.4

Disposal Group Not Discontinued Operation Gain Loss On Disposal

us-gaap:DisposalGroupNotDiscontinuedOperationGainLossOnDisposal

us-gaap:DisposalGroupNotDiscontinuedOperationGainLossOnDisposal


Disposal
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-09-30
Value-2.0359-2.085-2.00.0147.04.0130.02.0-3.02.00.00.00.01.0
Percentage of DisposalGroupNotDiscontinuedOperationGainLossOnDisposal100.0100.0100.0100.0100.00.0100.0100.0100.0100.00.0100.0100.0100.00.00.00.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.114.00.04.3-0.10.01.70.80.41.40.00.2-0.30.20.00.00.00.1

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

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value282832602168177391675100187360477367426480-35.0
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.632.50.08.48.416.125.15.19.215.720.12.03.811.63.8-1.9

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxExpenseBenefit


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value969611946757812420386794-10.09.043-173.0198.046-107.0-26.019184.0-112.01956352.0596334112948-13.010.03668-2.02.0311.02810.03567
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.33.70.02.33.63.24.61.01.92.94.0-0.50.51.9-8.31.00.42.0-5.6-1.51.00.80.4-13.22.15.23.70.26.35.73.71.43.34.6-1.51.34.36.7-0.20.33.60.13.41.44.46.9

us-gaap:IncomeTaxExpenseBenefit us-gaap:TaxPeriod, us-gaap:UnusualRiskOrUncertaintyByNature

wltw:TaxYear2019And2020, wltw:CARES


Income
Period End2020-09-302020-06-30
Value3.035
Percentage of IncomeTaxExpenseBenefit6.546.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.21.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:TaxYear2019And2020 wltw:CARES0.00.0

Interest Expense

us-gaap:InterestExpense

us-gaap:InterestExpense


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value52596061626162625654545152514947464646454746393535333434353233303231313233324438344042404143
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.32.30.03.13.02.52.33.22.82.42.32.82.62.22.42.52.42.02.42.52.42.14.04.13.83.03.54.23.72.93.63.83.62.93.64.23.93.25.45.03.94.05.05.55.14.4

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value18473347612194305544751382873784458215245-54.033344142-32.072238-24.01177021076-7.04724668-27.0105219-805.02610822525608534986489204
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.228.60.06.14.512.520.23.86.812.615.92.43.09.511.8-2.91.714.87.4-1.83.710.7-2.513.87.619.37.9-0.95.022.47.4-3.411.820.8-92.43.412.822.23.17.99.83.411.88.711.121.0

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2.03.07.01.08.08.07.05.0116.05.02.07.06.08.00.08.08.06.01.04.07.06.0-1.02.04.07.0-1.01.04.06.00.02.04.04.00.02.07.04.00.04.08.05.01.02.07.0
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.00.10.40.30.30.30.50.30.20.10.40.30.40.00.40.30.30.10.20.30.6-0.10.20.40.7-0.10.10.40.70.00.20.40.50.00.20.70.50.00.50.80.60.10.30.7

Operating Income Loss

us-gaap:OperatingIncomeLoss

us-gaap:OperatingIncomeLoss


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value26045258773163360687107176359470176325911041124463881.01363262.0271052931393414832615275171287-775.0701793178190157238177106169301
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.617.60.03.77.814.825.55.48.715.719.80.93.211.45.32.26.320.04.60.17.014.60.23.211.427.014.54.215.829.716.59.419.227.3-89.09.321.331.39.911.818.223.621.214.521.231.0

Other Comprehensive Income Loss Net Of Tax

us-gaap:OtherComprehensiveIncomeLossNetOfTax

us-gaap:OtherComprehensiveIncomeLossNetOfTax


Other
Period End2021-06-302021-03-312020-06-302020-03-312019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value335056-220.0-17.022-22.0-176.08417788140-21.0-673.0-42.0-138.0-14.0-86.0-86.084107-336.0-76.0258.0115736.0-37.0-133.027-32.032
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.52.02.7-9.0-0.81.0-1.2-9.03.78.54.87.2-0.9-34.9-2.4-7.1-0.6-8.8-10.29.19.8-35.1-9.42.70.712.59.20.7-3.5-15.33.6-3.83.2

us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents

us-gaap:AociIncludingPortionAttributableToNoncontrollingInterest


Other
Period End2021-06-302021-03-312020-06-302020-03-31
Value334856-219.0
Percentage of OtherComprehensiveIncomeLossNetOfTax100.096.0100.099.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.51.92.7-9.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AociIncludingPortionAttributableToNoncontrollingInterest0.00.00.00.0

us-gaap:NoncontrollingInterest


Other
Period End2021-03-312020-03-31
Value2.0-1.0
Percentage of OtherComprehensiveIncomeLossNetOfTax4.00.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.00.0

us-gaap:Parent


Other
Period End2021-06-302021-03-312020-06-302020-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value334856-219.0-83.0-82.080114-331.0-75.0
Percentage of OtherComprehensiveIncomeLossNetOfTax100.096.0100.099.596.595.395.2106.598.598.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.51.92.7-9.0-8.5-9.78.710.5-34.6-9.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Parent0.00.00.00.00.00.00.00.00.00.0

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherNonoperatingIncomeExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value74439751567692505567556170635618-29.0-30.0-20.0-1.0-14.06.0-18.0299.023-6.018-9.0-3.00.07.05.04.06.0
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.317.10.07.83.63.81.92.83.32.42.63.83.22.50.9-1.6-1.5-0.9-0.1-0.80.3-0.83.01.12.5-0.61.9-1.1-0.30.00.80.60.40.6

us-gaap:OtherNonoperatingIncomeExpense us-gaap:ConsolidationItems

us-gaap:MaterialReconcilingItems


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
Value74439751567692505567556170-63.0564938-34.043
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0-100.0100.0272.2-131.0113.3-215.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.317.10.07.83.63.81.92.83.32.42.63.8-3.22.52.42.1-1.71.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems0.00.00.03900.0400.0340.70.0250.0319.0211.50.0700.0-262.5294.70.00.00.00.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value186736483122102313551801492933834665221253-54.041352148-31.076245-18.01167221483-8.04825074-27.0107223-801.026110232296089421036591211
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.328.70.06.14.912.920.54.17.312.816.12.53.39.712.2-2.92.115.27.7-1.73.911.0-1.813.77.819.78.7-1.05.122.88.1-3.412.021.2-92.03.413.122.93.57.910.34.212.48.911.421.7

Revenue From Contract With Customer Excluding Assessed Tax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value224525622752199921012434269019662030228623721826196622742078185219532319192717771949223497484692210879588129351097919795890105187175484210138197628631008833733799972
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2.0-2.01.02.03.03.03.04.04.04.04.04.05.04.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.10.00.10.10.10.10.20.20.20.20.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.10.00.10.10.10.10.20.20.20.20.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MaterialReconcilingItems


Revenue
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
Value244.01927362221264110.02419
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.90.20.91.11.31.11.01.11.70.51.20.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.90.20.91.11.31.11.01.11.70.51.20.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments


Revenue
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
Value272819952082240726231944200922602306181619422255
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax99.199.899.198.997.598.999.098.997.299.598.899.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax99.199.899.198.997.598.999.098.997.299.598.899.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:ProductOrService

us-gaap:OperatingSegments, us-gaap:Service


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value2229255320822407
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax99.399.699.198.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax99.399.699.198.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, us-gaap:Service, wltw:BenefitsDeliveryAndAdministration


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value242284209231
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.811.19.99.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.811.19.99.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value753790694721
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.530.833.029.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.530.833.029.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:CorporateRiskAndBroking100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value833872765840
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax37.134.036.434.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax37.134.036.434.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:HumanCapitalAndBenefits100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value398604411612
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.723.619.625.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.723.619.625.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0

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

us-gaap:CorporateNonSegment, us-gaap:Service, srt:NorthAmerica


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value3.02.02.02.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment us-gaap:Service srt:NorthAmerica100.0100.0100.0100.0

us-gaap:CorporateNonSegment, us-gaap:Service, wltw:WesternEurope


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value0.01.01.01.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment us-gaap:Service wltw:WesternEurope0.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, srt:NorthAmerica


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value1152118510841110
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax51.346.351.645.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax51.346.351.645.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service srt:NorthAmerica100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:GreatBritain


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value521613484584
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax23.223.923.024.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax23.223.923.024.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:GreatBritain100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:International


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value249263218236
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.110.310.49.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.110.310.49.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:International100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:WesternEurope


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value307492296477
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.719.214.119.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.719.214.119.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:WesternEurope100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementGeographical, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, us-gaap:Service, srt:NorthAmerica, wltw:BenefitsDeliveryAndAdministration


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value239282207229
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.611.09.99.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.611.09.99.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service srt:NorthAmerica wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, srt:NorthAmerica, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value308247296233
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.79.614.19.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.79.614.19.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service srt:NorthAmerica wltw:CorporateRiskAndBroking100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, srt:NorthAmerica, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value477468462476
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax21.218.322.019.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax21.218.322.019.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service srt:NorthAmerica wltw:HumanCapitalAndBenefits100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, srt:NorthAmerica, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value125186117170
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.67.35.67.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.67.35.67.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service srt:NorthAmerica wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:GreatBritain, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value173155160137
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.76.07.65.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.76.07.65.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:GreatBritain wltw:CorporateRiskAndBroking100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:GreatBritain, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value143147117126
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.45.75.65.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.45.75.65.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:GreatBritain wltw:HumanCapitalAndBenefits100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:GreatBritain, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value205311207321
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.112.19.913.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.112.19.913.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:GreatBritain wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:International, wltw:BenefitsDeliveryAndAdministration


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value3.02.02.02.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:International wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:International, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value128127111107
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.75.05.34.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.75.05.34.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:International wltw:CorporateRiskAndBroking100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:International, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value75866782
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.33.43.23.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.33.43.23.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:International wltw:HumanCapitalAndBenefits100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:International, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value43483845
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.91.91.81.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.91.91.81.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:International wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:WesternEurope, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value144261127244
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.410.26.010.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.410.26.010.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:WesternEurope wltw:CorporateRiskAndBroking100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:WesternEurope, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value138171119156
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.16.75.76.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.16.75.76.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:WesternEurope wltw:HumanCapitalAndBenefits100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Service, wltw:WesternEurope, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value25594976
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.12.32.33.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.12.32.33.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Service wltw:WesternEurope wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:MaterialReconcilingItems, us-gaap:CorporateNonSegment


Revenue
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
Value1.0-9.04.06.010.03.02.07.019-7.04.01.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0-0.50.20.20.40.20.10.30.8-0.40.20.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0-0.50.20.20.40.20.10.30.8-0.40.20.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MaterialReconcilingItems, wltw:BenefitsDeliveryAndAdministration


Revenue
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
Value5.02.02.03.05.02.02.03.02.01.02.02.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.10.10.20.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.10.10.20.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MaterialReconcilingItems, wltw:CorporateRiskAndBroking


Revenue
Period End2020-12-312020-09-302020-06-302018-12-312018-09-30
Value1.00.01.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems wltw:CorporateRiskAndBroking100.00.0100.00.00.0

us-gaap:MaterialReconcilingItems, wltw:HumanCapitalAndBenefits


Revenue
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
Value1410.011151715151417141714
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.50.50.60.60.80.70.60.70.80.90.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.50.50.60.60.80.70.60.70.80.90.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MaterialReconcilingItems, wltw:InvestmentRiskAndReinsurance


Revenue
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
Value3.01.01.03.03.02.02.02.03.02.01.02.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.00.10.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.00.10.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:CorporateNonSegment


Revenue
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
Value1.02.03.03.03.04.04.04.04.04.05.04.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.10.10.10.20.20.20.20.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.10.10.10.20.20.20.20.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:BenefitsDeliveryAndAdministration


Revenue
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
Value693226209231595179126135390127119122
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax25.211.39.99.522.19.16.25.916.47.06.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax25.211.39.99.522.19.16.25.916.47.06.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:CorporateRiskAndBroking


Revenue
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
Value880643694721861637683719808606667734
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.032.233.029.632.032.433.631.534.133.233.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.032.233.029.632.032.433.631.534.133.233.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:HumanCapitalAndBenefits


Revenue
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
Value862794765840856804792823833773775828
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax31.339.736.434.531.840.939.036.035.142.339.436.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax31.339.736.434.531.840.939.036.035.142.339.436.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:InvestmentRiskAndReinsurance


Revenue
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
Value292330411612308320404579271306376567
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.616.519.625.111.416.319.925.311.416.819.124.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.616.519.625.111.416.319.925.311.416.819.124.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:StatementGeographical

us-gaap:CorporateNonSegment, srt:NorthAmerica


Revenue
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
Value2.01.02.02.01.04.04.04.03.04.05.04.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.00.20.20.20.10.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.00.20.20.20.10.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment srt:NorthAmerica100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CorporateNonSegment, wltw:WesternEurope


Revenue
Period End2020-12-312020-09-302020-06-302020-03-312018-12-312018-09-30
Value-1.01.01.01.01.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.00.10.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.00.10.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment wltw:WesternEurope100.0100.0100.0100.0100.00.0

us-gaap:OperatingSegments, srt:NorthAmerica


Revenue
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
Value1600107310841110147410419999941226946955956
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax58.153.751.645.654.853.049.243.551.751.848.642.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax58.153.751.645.654.853.049.243.551.751.848.642.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:GreatBritain


Revenue
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
Value469408484584469402488560428389472572
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.020.423.024.017.420.424.024.518.021.324.025.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.020.423.024.017.420.424.024.518.021.324.025.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:GreatBritain100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:International


Revenue
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
Value262226218236277226219243264217219263
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.511.310.49.710.311.510.810.611.111.911.111.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.511.310.49.710.311.510.810.611.111.911.111.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:International100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:WesternEurope


Revenue
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
Value397288296477403275303463388264296464
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax14.414.414.119.615.014.014.920.316.414.515.120.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax14.414.414.119.615.014.014.920.316.414.515.120.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:WesternEurope100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:StatementGeographical, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, srt:NorthAmerica, wltw:BenefitsDeliveryAndAdministration


Revenue
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
Value691224207229593179126135390127119122
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax25.111.29.99.422.09.16.25.916.47.06.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax25.111.29.99.422.09.16.25.916.47.06.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, srt:NorthAmerica, wltw:CorporateRiskAndBroking


Revenue
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
Value360287296233330288274220304266259215
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.114.414.19.612.314.613.59.612.814.613.29.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.114.414.19.612.314.613.59.612.814.613.29.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, srt:NorthAmerica, wltw:HumanCapitalAndBenefits


Revenue
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
Value456465462476470482478471454466467462
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.623.322.019.617.524.523.520.619.125.523.820.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.623.322.019.617.524.523.520.619.125.523.820.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, srt:NorthAmerica, wltw:InvestmentRiskAndReinsurance


Revenue
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
Value919611717080881171647583105153
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.34.85.67.03.04.55.87.23.24.55.36.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.34.85.67.03.04.55.87.23.24.55.36.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:GreatBritain, wltw:CorporateRiskAndBroking


Revenue
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
Value195138160137203139172142193137170148
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.16.97.65.67.57.18.56.28.17.58.66.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.16.97.65.67.57.18.56.28.17.58.66.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:GreatBritain wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:GreatBritain, wltw:HumanCapitalAndBenefits


Revenue
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
Value128120117126121116120118119113120129
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.76.05.65.24.55.95.95.25.06.26.15.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.76.05.65.24.55.95.95.25.06.26.15.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:GreatBritain wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:GreatBritain, wltw:InvestmentRiskAndReinsurance


Revenue
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
Value146150207321145147196300116139182295
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.37.59.913.25.47.59.713.14.97.69.313.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.37.59.913.25.47.59.713.14.97.69.313.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:GreatBritain wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:International, wltw:BenefitsDeliveryAndAdministration


Revenue
Period End2020-12-312020-09-302020-06-302020-03-312018-09-30
Value2.02.02.02.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:International wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.00.0

us-gaap:OperatingSegments, wltw:International, wltw:CorporateRiskAndBroking


Revenue
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
Value129106111107139105109118136107117132
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.75.35.34.45.25.35.45.25.75.96.05.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.75.35.34.45.25.35.45.25.75.96.05.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:International wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:International, wltw:HumanCapitalAndBenefits


Revenue
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
Value9880678210183707997736483
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.64.03.23.43.84.23.43.54.14.03.33.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.64.03.23.43.84.23.43.54.14.03.33.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:International wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:International, wltw:InvestmentRiskAndReinsurance


Revenue
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
Value333838453438404631373848
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.21.91.81.81.31.92.02.01.32.01.92.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.21.91.81.81.31.92.02.01.32.01.92.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:International wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:WesternEurope, wltw:CorporateRiskAndBroking


Revenue
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
Value19611212724418910512823917596121239
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.15.66.010.07.05.36.310.57.45.36.210.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.15.66.010.07.05.36.310.57.45.36.210.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:WesternEurope wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:WesternEurope, wltw:HumanCapitalAndBenefits


Revenue
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
Value180129119156164123124155163121124154
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.56.55.76.46.16.36.16.86.96.66.36.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.56.55.76.46.16.36.16.86.96.66.36.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:WesternEurope wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:WesternEurope, wltw:InvestmentRiskAndReinsurance


Revenue
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
Value224649764947516949475171
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.82.32.33.11.82.42.53.02.12.62.63.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.82.32.33.11.82.42.53.02.12.62.63.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:WesternEurope wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductOrService

us-gaap:ProductAndServiceOther


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1321191251319813213412511010711711389106
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.94.64.56.64.75.45.06.45.44.74.96.24.54.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.94.64.56.64.75.45.06.45.44.74.96.24.54.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Service


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value2229255320822407
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax99.399.699.198.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax99.399.699.198.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Service100.0100.0100.0100.0

wltw:Broking


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value109413781600932105612621486877955114112097788991135
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax48.753.858.146.650.351.855.244.647.049.951.042.645.749.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax48.753.858.146.650.351.855.244.647.049.951.042.645.749.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value739763715660668724719676710728566718751795
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.929.826.033.031.829.726.734.435.031.823.939.338.235.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.929.826.033.031.829.726.734.435.031.823.939.338.235.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value264293288272260289284266234284414207247273
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.811.410.513.612.411.910.613.511.512.417.511.312.612.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.811.410.513.612.411.910.613.511.512.417.511.312.612.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ProductAndServiceOther, us-gaap:CorporateNonSegment


Revenue
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
Value0.01.01.01.01.01.01.01.00.01.02.01.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.00.00.00.10.00.00.00.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.00.00.00.10.00.00.00.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther us-gaap:CorporateNonSegment0.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0

us-gaap:ProductAndServiceOther, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value5.04.05.04.01.01.02.01.01.01.03.01.02.03.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.20.20.20.00.00.10.10.00.00.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.20.20.20.00.00.10.10.00.00.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductAndServiceOther, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value5049767741478079564771734043
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.21.92.83.92.01.93.04.02.82.13.04.02.01.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.21.92.83.92.01.93.04.02.82.13.04.02.01.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductAndServiceOther, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value7665444955835144525843384559
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.42.51.62.52.63.41.92.22.62.51.82.12.32.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.42.51.62.52.63.41.92.22.62.51.82.12.32.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Service, wltw:BenefitsDeliveryAndAdministration


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value242284209231
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.811.19.99.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.811.19.99.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Service wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0

us-gaap:Service, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value753790694721
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.530.833.029.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.530.833.029.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Service wltw:CorporateRiskAndBroking100.0100.0100.0100.0

us-gaap:Service, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value833872765840
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax37.134.036.434.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax37.134.036.434.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Service wltw:HumanCapitalAndBenefits100.0100.0100.0100.0

us-gaap:Service, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value398604411612
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.723.619.625.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.723.619.625.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Service wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0

wltw:Broking, wltw:BenefitsDeliveryAndAdministration


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1211525461009098447559.03.02604.04.04.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.45.919.85.04.34.016.62.80.40.111.00.20.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.45.919.85.04.34.016.62.80.40.111.00.20.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Broking, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value687717830592637648810589633660750554610664
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax30.628.030.229.630.326.630.130.031.228.931.630.331.029.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax30.628.030.229.630.326.630.130.031.228.931.630.331.029.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Broking, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value8397866271838358647375546176
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.73.83.13.13.43.43.13.03.23.23.23.03.13.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.73.83.13.13.43.43.13.03.23.23.23.03.13.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Broking, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value203412137178258433146175249405124166224391
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.016.15.08.912.317.85.48.912.317.75.29.111.417.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.016.15.08.912.317.85.48.912.317.75.29.111.417.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting, us-gaap:CorporateNonSegment


Revenue
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
Value0.01.02.02.02.03.03.03.04.03.03.03.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.10.10.10.20.10.10.20.20.20.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.10.10.10.20.10.10.20.20.20.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting us-gaap:CorporateNonSegment0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4644363140473530363143373944
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.01.71.31.61.91.91.31.51.81.41.82.02.01.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.01.71.31.61.91.91.31.51.81.41.82.02.01.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value576594573529531582573545571580415576558577
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax25.723.220.826.525.323.921.327.728.125.417.531.528.425.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax25.723.220.826.525.323.921.327.728.125.417.531.528.425.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value11512310699959310998100114104102107117
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.14.83.95.04.53.84.15.04.95.04.45.65.45.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.14.83.95.04.53.84.15.04.95.04.45.65.45.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration, wltw:BenefitsDeliveryAndAdministration


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value121132147126119133148124117132130123115118
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.45.25.36.35.75.55.56.35.85.85.56.75.85.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.45.25.36.35.75.55.56.35.85.85.56.75.85.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration, wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value15259.01616251417132712141623
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.71.00.30.80.81.00.50.90.61.20.50.80.81.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.71.00.30.80.81.00.50.90.61.20.50.80.81.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration, wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value12413212712612212812012210112327270116132
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.55.24.66.35.85.34.56.25.05.411.53.85.95.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.55.24.66.35.85.34.56.25.05.411.53.85.95.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration, wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value4.04.05.04.03.03.02.03.03.02.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.20.20.20.10.10.10.20.10.10.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.20.20.20.10.10.10.20.10.10.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:StatementBusinessSegments

us-gaap:CorporateNonSegment


Revenue
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
Value2.0-7.07.09.0137.06.01123-3.09.05.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.40.30.40.50.40.30.51.0-0.20.50.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.40.30.40.50.40.30.51.0-0.20.50.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:BenefitsDeliveryAndAdministration


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value244286698228211234600181128138392128121124
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.911.225.411.410.09.622.39.26.36.016.57.06.25.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.911.225.411.410.09.622.39.26.36.016.57.06.25.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:CorporateRiskAndBroking


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value754790881643695721862637683719808606667734
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.630.832.032.233.129.632.032.433.631.534.133.233.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.630.832.032.233.129.632.032.433.631.534.133.233.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:HumanCapitalAndBenefits


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value845883876804776855873819807837850787792842
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax37.634.531.840.236.935.132.541.739.836.635.843.140.337.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax37.634.531.840.236.935.132.541.739.836.635.843.140.337.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:InvestmentRiskAndReinsurance


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value400605295331412615311322406581274308377569
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.823.610.716.619.625.311.616.420.025.411.616.919.225.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.823.610.716.619.625.311.616.420.025.411.616.919.225.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenues

us-gaap:Revenues

us-gaap:Revenues


Revenues
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value228625902764200921132466269019892048231223721859199022922078185219532319192717771949223497484692210879588129351097919795890105187175484210138197628631008833733799972
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax101.8101.1100.4100.5100.6101.3100.0101.2100.9101.1100.0101.8101.2100.8100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Revenues us-gaap:BusinessAcquisition

wltw:TRANZACTAcquisition


Revenuesus-gaap:
Period End2020-09-302020-06-302020-03-312019-09-30
Value96879551
Percentage of Revenues4.84.13.92.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.84.13.90.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:TRANZACTAcquisition0.00.00.00.0

us-gaap:Revenues us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Revenuesus-gaap:
Period End2021-06-302021-03-312020-06-302020-03-31
Value3.0-1.08.010.0
Percentage of Revenues0.1-0.00.40.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.00.40.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment150.050.0266.7333.3

us-gaap:MaterialReconcilingItems


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value2013267.02331392726314315322435173126
Percentage of Revenues0.90.50.90.31.11.31.41.41.31.31.80.81.61.01.70.91.61.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.90.50.90.41.11.31.41.41.31.41.80.81.61.11.70.91.61.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems0.00.0108.3175.0121.1114.8108.3122.7123.8119.2104.9150.0133.3126.30.00.00.00.0

us-gaap:OperatingSegments


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value22662577273820022090243526511962202222812329184419582268204718351926229619011761194822259748469221081
Percentage of Revenues99.199.599.199.798.998.798.698.698.798.798.299.298.499.098.599.198.699.098.799.199.999.6100.0100.0100.099.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.9100.699.5100.299.5100.098.699.899.699.898.2101.099.699.798.599.198.699.098.799.199.999.6100.0100.0100.099.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments0.00.0100.4100.4100.4101.2101.1100.9100.6100.9101.0101.5100.8100.60.00.00.00.00.00.00.00.00.00.00.00.0

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

us-gaap:OperatingSegments, wltw:BenefitsDeliveryAndAdministration


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value242287693226209231595179126135390127119122194181
Percentage of Revenues10.611.125.111.29.99.422.19.06.25.816.46.86.05.39.39.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.811.225.211.39.99.522.19.16.25.916.47.06.15.49.39.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:BenefitsDeliveryAndAdministration0.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0

us-gaap:OperatingSegments, wltw:CorporateRiskAndBroking


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value788810888649701739877651690728816622674740793600
Percentage of Revenues34.531.332.132.333.230.032.632.733.731.534.433.533.932.338.232.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax35.131.632.332.533.430.432.633.134.031.834.434.134.332.538.232.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:CorporateRiskAndBroking0.00.0100.9100.9101.0102.5101.9102.2101.0101.3101.0102.6101.0100.80.00.0

us-gaap:OperatingSegments, wltw:HumanCapitalAndBenefits


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value836875865796767850865807797829843778780832768733
Percentage of Revenues36.633.831.339.636.334.532.240.638.935.935.541.939.236.337.039.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax37.234.231.439.836.534.932.241.039.336.335.542.639.736.637.039.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:HumanCapitalAndBenefits0.00.0100.3100.3100.3101.2101.1100.4100.6100.7101.2100.6100.6100.50.00.0

us-gaap:OperatingSegments, wltw:InvestmentRiskAndReinsurance


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value400605292331413615314325409589280317385574288321
Percentage of Revenues17.523.410.616.519.524.911.716.320.025.511.817.119.325.013.917.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.823.610.616.619.725.311.716.520.125.811.817.419.625.213.917.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:InvestmentRiskAndReinsurance0.00.0100.0100.3100.5100.5101.9101.6101.2101.7103.3103.6102.4101.20.00.0

us-gaap:Revenues us-gaap:StatementBusinessSegments

us-gaap:CorporateNonSegment


Revenuesus-gaap:
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
Value3.0-6.08.010.0138.07.01221-2.0126.0
Percentage of Revenues0.1-0.30.40.40.50.40.30.50.9-0.10.60.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.30.40.40.50.40.30.50.9-0.10.60.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment150.085.7114.3111.1100.0114.3116.7109.191.366.7133.3120.0

wltw:BenefitsDeliveryAndAdministration


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value244289698228211234600181128138392128121124
Percentage of Revenues10.711.225.311.310.09.522.39.16.26.016.56.96.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.911.325.411.410.09.622.39.26.36.016.57.06.25.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:BenefitsDeliveryAndAdministration100.0101.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:CorporateRiskAndBroking


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value789810889649702739878651690728816622674740
Percentage of Revenues34.531.332.232.333.230.032.632.733.731.534.433.533.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax35.131.632.332.533.430.432.633.134.031.834.434.134.332.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:CorporateRiskAndBroking104.6102.5100.9100.9101.0102.5101.9102.2101.0101.3101.0102.6101.0100.8

wltw:HumanCapitalAndBenefits


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value848886879806778865882822812843860792797846
Percentage of Revenues37.134.231.840.136.835.132.841.339.636.536.342.640.136.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax37.834.631.940.337.035.532.841.840.036.936.343.440.537.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:HumanCapitalAndBenefits100.4100.3100.3100.2100.3101.2101.0100.4100.6100.7101.2100.6100.6100.5

wltw:InvestmentRiskAndReinsurance


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value402606295332414618317327411591283319386576
Percentage of Revenues17.623.410.716.519.625.111.816.420.125.611.917.219.425.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.923.710.716.619.725.411.816.620.225.911.917.519.625.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:InvestmentRiskAndReinsurance100.5100.2100.0100.3100.5100.5101.9101.6101.2101.7103.3103.6102.4101.2

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value3826738632385313803738110377273542635703351663589332385330413421334212324583227232774322323025331801324093302918839178131831916105154351520816551158281480015323159381580215112170031760817091157281661517941172381584715625
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Liabilities

us-gaap:Liabilities

us-gaap:Liabilities


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2655227058275992741727654273382505725672249342565122388228512383923382221812219122330217752001920847211692167216426152751577813733133691293514089133561255713276139381390913387143051489714387132111389815202145691323913396
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets69.470.071.672.172.672.570.771.970.971.569.169.269.768.368.368.868.167.666.265.665.365.687.285.886.185.386.685.185.184.484.886.687.588.088.684.184.684.284.083.684.784.583.585.7

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value3826738632385313803738110377273542635703351663589332385330413421334212324583227232774322323025331801324093302918839178131831916105154351520816551158281480015323159381580215112170031760817091157281661517941172381584715625
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-31
Value1167011526108201051510335102631024998871009010092985210049102281067210126991510263102781006510767110501115122292393239322981985225824442442221520241977186516992674268726752486268827072630257721801845
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.529.828.127.627.127.228.927.728.728.130.430.429.931.231.230.731.331.933.333.934.133.811.813.413.114.312.914.814.815.415.013.212.411.811.215.715.315.715.816.215.115.316.314.00.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value-1915.0-1928.0-1968.0-1677.0-1686.0-1695.0-1702.0-1360.0-1363.0-1370.0-1337.0-1073.0-1094.0-1132.0-1138.0-1122.0-1152.0-707.0-710.0-711.0-713.0-660.0-680.0-663.0-893.0-714.0
Percentage of StockholdersEquity-16.4-16.7-18.2-15.9-16.3-16.5-16.6-13.8-13.5-13.6-13.6-10.7-10.7-10.6-11.2-10.9-11.4-6.6-6.4-6.4-32.0-27.6-28.4-28.9-45.0-32.2
Percentage of Assets-5.0-5.0-5.1-4.4-4.4-4.5-4.8-3.8-3.9-3.8-4.1-3.2-3.2-3.3-3.5-3.5-3.8-2.2-2.2-2.2-3.8-3.7-3.7-4.1-5.8-4.8
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-2278.0-2311.0-2359.0-2253.0-2390.0-2446.0-2227.0-2113.0-1993.0-1974.0-1961.0-1627.0-1605.0-1430.0-1513.0-1908.0-1884.0-1221.0-1181.0-1053.0-1037.0-954.0-872.0-952.0-1066.0-693.0-744.0-541.0-594.0-630.0-153.0
Percentage of StockholdersEquity-19.5-20.1-21.8-21.4-23.1-23.8-21.7-21.4-19.8-19.6-19.9-16.2-15.7-13.4-14.9-18.6-18.7-11.3-10.7-9.4-46.5-39.9-36.4-41.4-53.7-31.3-29.9-21.0-27.2-34.10.0
Percentage of Assets-6.0-6.0-6.1-5.9-6.3-6.5-6.3-5.9-5.7-5.5-6.1-4.9-4.7-4.2-4.7-5.9-6.2-3.8-3.6-3.2-5.5-5.4-4.8-5.9-6.9-4.7-4.7-3.4-3.80.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value-376.0-398.0-400.0-579.0-698.0-746.0-538.0-746.0-626.0-607.0-616.0-550.0-506.0-307.0-365.0-724.0-650.0-434.0-398.0-310.0-314.0-302.0-230.0-296.0-191.0-14.0
Percentage of StockholdersEquity-3.2-3.5-3.7-5.5-6.8-7.3-5.2-7.5-6.2-6.0-6.3-5.5-4.9-2.9-3.6-7.0-6.5-4.0-3.6-2.8-14.1-12.6-9.6-12.9-9.6-0.6
Percentage of Assets-1.0-1.0-1.0-1.5-1.8-2.0-1.5-2.1-1.8-1.7-1.9-1.7-1.5-0.9-1.1-2.2-2.1-1.4-1.2-0.9-1.7-1.7-1.3-1.8-1.2-0.1
Percentage of Assets us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312016-12-31
Value13159.03.0-6.0-5.013-7.0-4.03.0-8.0-10.0-82.0
Percentage of StockholdersEquity0.10.10.10.0-0.1-0.00.1-0.1-0.00.0-0.1-0.1-0.8
Percentage of Assets0.00.00.00.0-0.0-0.00.0-0.0-0.00.0-0.0-0.0-0.3
Percentage of Assets us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent0.00.00.00.00.00.00.00.00.00.00.00.00.0

Assets Current

us-gaap:AssetsCurrent

us-gaap:AssetsCurrent


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2056820872203011991419922195501703717400183331902016420167561788917606158611569116233157951379214733152301557912503123341294611328108531082412072114451046111014116741159510898121161272612217109871170012981123041110010975
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets53.754.052.752.452.351.848.148.752.153.050.750.752.351.548.948.649.549.045.646.347.047.266.469.270.770.370.371.272.972.370.771.973.273.472.171.372.371.569.970.472.471.470.070.2

Cash

us-gaap:Cash dei:LegalEntity, us-gaap:Range

us-gaap:Cash

wltw:WillisLimited, srt:Minimum


Cashdei:
Period End2020-12-31
Value51
Percentage of Cash100.0
Percentage of Assets0.1
Percentage of Assets wltw:WillisLimited srt:Minimum0.0

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashAndCashEquivalentsAtCarryingValue


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value2217196020891647108789888786781299210339319119541030912852901870767949954532466483503635656708734796623503531500424407464436363317432316159167222221205200
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.85.15.44.32.92.42.52.42.32.83.22.82.72.83.22.82.62.82.92.42.92.92.82.62.63.14.14.34.34.65.44.13.23.43.32.52.32.72.82.21.82.52.00.00.00.01.40.00.0

us-gaap:CashAndCashEquivalentsAtCarryingValue dei:LegalEntity, us-gaap:Range

wltw:WillisLimited, srt:Minimum


Cash
Period End2020-12-31
Value140
Percentage of CashAndCashEquivalentsAtCarryingValue6.7
Percentage of Assets0.4
Percentage of Assets wltw:WillisLimited srt:Minimum0.0

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312016-12-31
Value2221196620961654109490689587481299210339311030870
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.85.15.44.32.92.42.52.42.32.83.22.83.22.9

Accounts Receivable Net Current

us-gaap:AccountsReceivableNetCurrent

us-gaap:AccountsReceivableNetCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value250725692555222324302594262121672461249023792132239426002246215522882307208020432187226812581100122611501044102111751185104198510441051933908102210099109111049992839816
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.66.66.65.86.46.97.46.17.06.97.36.57.07.66.96.77.07.26.96.46.76.96.76.26.77.16.86.77.17.57.06.46.66.76.25.35.85.95.85.55.85.85.35.2

Other Assets Current

us-gaap:OtherAssetsCurrent

us-gaap:OtherAssetsCurrent


Other
Period End2021-03-312020-12-312020-06-302020-03-312019-12-312019-09-302019-06-302018-12-312018-09-302017-12-312017-09-302016-12-312016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value5375471001128981576871675549255240222218214229195204197195207186181317309325259315327369340198
Percentage of OtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.20.10.30.30.20.20.20.20.20.20.20.11.41.31.21.41.41.51.21.31.31.31.31.21.21.91.81.91.61.91.82.12.11.3

Prepaid Expense And Other Assets Current

us-gaap:PrepaidExpenseAndOtherAssetsCurrent

us-gaap:PrepaidExpenseAndOtherAssetsCurrent


Prepaid
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value465432497484363469525587451409404547458439430418342321337319327326255
Percentage of PrepaidExpenseAndOtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.21.11.31.31.01.21.51.61.31.11.21.71.31.31.31.31.01.01.11.01.01.01.4

Noncurrent Assets

us-gaap:NoncurrentAssets

us-gaap:NoncurrentAssets


Noncurrent
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value181351831715906165511641162604563
Percentage of NoncurrentAssets100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets47.151.749.151.054.233.229.6

us-gaap:NoncurrentAssets us-gaap:StatementGeographical

country:GB


Noncurrent
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value2840290123493173243124261666233218
Percentage of NoncurrentAssets15.715.814.819.214.838.836.50.00.0
Percentage of Assets7.48.27.39.88.012.910.81.61.4
Percentage of Assets country:GB0.00.00.00.00.00.00.00.00.0

country:IE


Noncurrent
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value11010378127114124121
Percentage of NoncurrentAssets0.60.60.50.80.72.02.7
Percentage of Assets0.30.30.20.40.40.70.8
Percentage of Assets country:IE0.00.00.00.00.00.00.0

country:US


Noncurrent
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value12652127861106899881140017591800203207
Percentage of NoncurrentAssets69.869.869.660.369.528.139.40.00.0
Percentage of Assets32.836.134.230.837.79.311.71.41.4
Percentage of Assets country:US0.00.00.00.00.00.00.00.00.0

wltw:ForeignCountries


Noncurrent
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value180251821415828164241629761364442
Percentage of NoncurrentAssets99.499.499.599.299.398.097.3
Percentage of Assets46.851.448.950.653.932.628.8
Percentage of Assets wltw:ForeignCountries0.00.00.00.00.00.00.0

wltw:RestOfWorld


Noncurrent
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value253325272411326324661951976
Percentage of NoncurrentAssets14.013.815.219.715.031.221.4
Percentage of Assets6.67.17.410.18.210.46.3
Percentage of Assets wltw:RestOfWorld0.00.00.00.00.00.00.0

Assets Noncurrent

us-gaap:AssetsNoncurrent

us-gaap:AssetsNoncurrent


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value176991776018230181231818818177183891830316833168731596516285163241660616597165811654116437164611706817179174506336547953734777458243844479438343394309426442074214488748824874474149154960493447474650
Percentage of AssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets46.346.047.347.647.748.251.951.347.947.049.349.347.748.551.151.450.551.054.453.753.052.833.630.829.329.729.728.827.127.729.328.126.826.627.928.727.728.530.129.627.628.630.029.8

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:PropertyPlantAndEquipmentGross


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value214119421710186214811091980949881792753708
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.65.55.35.74.95.86.36.45.85.04.84.5

us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType

us-gaap:FurnitureAndFixtures


Property
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
Value14731302113013001009724642618576509488473
Percentage of PropertyPlantAndEquipmentGross68.867.066.169.868.166.465.565.165.464.364.866.8
Percentage of Assets3.83.73.54.03.33.84.24.23.83.23.13.0
Percentage of Assets us-gaap:FurnitureAndFixtures0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LandAndBuilding


Property
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
Value909092949095938978737351
Percentage of PropertyPlantAndEquipmentGross4.24.65.45.06.18.79.59.48.99.29.77.2
Percentage of Assets0.20.30.30.30.30.50.60.60.50.50.50.3
Percentage of Assets us-gaap:LandAndBuilding0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LeaseholdImprovements


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value578550488468382272245242227210192184
Percentage of PropertyPlantAndEquipmentGross27.028.328.525.125.824.925.025.525.826.525.526.0
Percentage of Assets1.51.61.51.41.31.41.61.61.51.31.21.2
Percentage of Assets us-gaap:LeaseholdImprovements0.00.00.00.00.00.00.00.00.00.00.00.0

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value1127896768877642528497468413386372356
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.92.52.42.72.12.83.23.22.72.52.32.3

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType

us-gaap:FurnitureAndFixtures


Accumulated
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
Value769594519652464393366345306297291286
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment68.266.367.674.372.374.473.673.774.176.978.280.3
Percentage of Assets2.01.71.62.01.52.12.42.32.01.91.81.8
Percentage of Assets us-gaap:FurnitureAndFixtures0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LandAndBuilding


Accumulated
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
Value625752494141383632282524
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment5.56.46.85.66.47.87.67.77.77.36.76.7
Percentage of Assets0.20.20.20.20.10.20.20.20.20.20.20.2
Percentage of Assets us-gaap:LandAndBuilding0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LeaseholdImprovements


Accumulated
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
Value29624519717613794938775615646
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment26.327.325.720.121.317.818.718.618.215.815.112.9
Percentage of Assets0.80.70.60.50.50.50.60.60.50.40.40.3
Percentage of Assets us-gaap:LeaseholdImprovements0.00.00.00.00.00.00.00.00.00.00.00.0

Amortization Of Intangible Assets

us-gaap:AmortizationOfIntangibleAssets

us-gaap:AmortizationOfIntangibleAssets


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value9810311410811912112111812312712612714014114014114915114815712516123231614161312131314141415141515
Percentage of AmortizationOfIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
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:AmortizationOfIntangibleAssets us-gaap:ConsolidationItems

us-gaap:MaterialReconcilingItems


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value98103114108119121121118123127126127140141140141149151
Percentage of AmortizationOfIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:MaterialReconcilingItems0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AmortizationOfIntangibleAssets us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value65697970757778757882909291100989910779110
Percentage of AmortizationOfIntangibleAssets66.367.069.364.863.063.664.563.663.464.664.365.264.567.164.966.968.263.268.3
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CustomerRelationships0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherIntangibleAssets


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value4.04.04.00.03.08.00.00.00.01.00.00.02.0-1.01.0
Percentage of AmortizationOfIntangibleAssets4.13.93.50.02.56.60.00.00.00.70.00.01.3-0.80.6
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:OtherIntangibleAssets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:SoftwareAndSoftwareDevelopmentCosts


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-31
Value181921272926303033323736373639353438
Percentage of AmortizationOfIntangibleAssets18.418.418.425.024.421.524.825.426.825.226.425.526.224.225.822.327.223.6
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:SoftwareAndSoftwareDevelopmentCosts0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TrademarksAndTradeNames


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value111110.0111210.01211111111111210.01212111210.0
Percentage of AmortizationOfIntangibleAssets11.210.78.810.210.18.39.99.38.98.77.97.88.56.77.98.17.09.66.2
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:TrademarksAndTradeNames0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:PropertyPlantAndEquipmentNet


Property
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value92795110149979899741046963967957942944924926985937895863839811794790563531516462483481496482481472452447468446428426406387391386381352
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.42.52.62.62.62.63.02.72.72.72.92.92.72.73.02.92.72.72.82.62.42.43.03.02.82.93.13.23.03.03.23.12.82.83.12.62.42.52.62.32.22.22.42.3

us-gaap:PropertyPlantAndEquipmentNet us-gaap:PropertyPlantAndEquipmentByType

us-gaap:FurnitureAndFixtures


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value704708611648545331276273270212197
Percentage of PropertyPlantAndEquipmentNet69.467.764.965.865.058.857.156.857.752.251.7
Percentage of Assets1.82.01.92.01.81.81.81.81.81.31.2
Percentage of Assets us-gaap:FurnitureAndFixtures0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LandAndBuilding


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value2833404549545553464548
Percentage of PropertyPlantAndEquipmentNet2.83.24.24.65.89.611.411.09.811.112.6
Percentage of Assets0.10.10.10.10.20.30.40.40.30.30.3
Percentage of Assets us-gaap:LandAndBuilding0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LeaseholdImprovements


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value282305291292245178152155152149136
Percentage of PropertyPlantAndEquipmentNet27.829.230.929.629.231.631.532.232.536.735.7
Percentage of Assets0.70.90.90.90.80.91.01.01.00.90.9
Percentage of Assets us-gaap:LeaseholdImprovements0.00.00.00.00.00.00.00.00.00.00.0

Goodwill

us-gaap:Goodwill

us-gaap:Goodwill


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value109951098611204111311119611162111941118710454104561046510457104681055510519105291050910442104131048310527104773737315030972889293728032870283528382846282928132827330432983308329532973317331232943277
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets28.728.429.129.329.429.631.631.329.729.132.331.630.630.932.432.632.132.434.433.032.531.719.817.716.917.919.018.417.317.919.218.617.817.818.719.418.719.420.919.818.519.220.821.0

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill


Intangible
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value27862878304331253257336034783561305531873318342935623761388240344156424543684589471350861115
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.37.47.98.28.58.99.810.08.78.910.210.410.411.012.012.512.713.214.414.414.515.45.9

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet

us-gaap:FiniteLivedIntangibleAssetsNet


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value27862878304331253257336034783561305531873318342935623761388240344156424543324553464949951115665675418450331360339353361373369385379391406420440461477492572
Percentage of FiniteLivedIntangibleAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.37.47.98.28.58.99.810.08.78.910.210.410.411.012.012.512.713.214.314.314.315.15.93.73.72.62.92.22.22.12.42.42.32.32.52.22.22.42.72.62.62.83.13.7

us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value1849190920342082213622042298234818221909198620472131226323422446252725812655280928563057920581588349373326353334345352364362377374387403417437458488
Percentage of FiniteLivedIntangibleAssetsNet66.466.366.866.665.665.666.165.959.659.959.959.759.860.260.360.660.860.861.361.761.461.282.587.487.183.582.998.598.198.597.797.597.698.197.998.799.099.399.399.399.399.2
Percentage of Assets4.84.95.35.55.65.86.56.65.25.36.16.26.26.67.27.67.78.08.88.88.89.34.93.33.22.22.42.12.12.12.32.32.32.32.52.22.22.42.72.62.63.1
Percentage of Assets us-gaap:CustomerRelationships0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherIntangibleAssets


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-31
Value677173781241151030.01.01.02.02.02.03.03.03.03.04.05.013321236.07.02.02.0
Percentage of FiniteLivedIntangibleAssetsNet2.42.52.42.53.83.43.00.00.00.00.10.10.00.10.10.10.10.10.111.93.23.41.41.60.60.5
Percentage of Assets0.20.20.20.20.30.30.30.00.00.00.00.00.00.00.00.00.00.00.00.70.10.10.00.00.00.0
Percentage of Assets us-gaap:OtherIntangibleAssets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:SoftwareAndSoftwareDevelopmentCosts


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value658310212114417620223126329832836339744247350854056857061665076877
Percentage of FiniteLivedIntangibleAssetsNet2.32.93.43.94.45.25.86.58.69.49.910.611.111.812.212.613.013.413.213.514.015.46.9
Percentage of Assets0.20.20.30.30.40.50.60.60.70.81.01.11.21.31.51.61.61.81.91.92.02.30.4
Percentage of Assets us-gaap:SoftwareAndSoftwareDevelopmentCosts0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TrademarksAndTradeNames


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value8058158348448538658758848989099209309439579669769879961006102010311044503.0
Percentage of FiniteLivedIntangibleAssetsNet28.928.327.427.026.225.725.224.829.428.527.727.126.525.424.924.223.723.523.222.422.220.94.50.7
Percentage of Assets2.12.12.22.22.22.32.52.52.62.52.82.82.82.83.03.03.03.13.33.23.23.20.30.0
Percentage of Assets us-gaap:TrademarksAndTradeNames0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OperatingLeaseRightOfUseAsset


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value8308419028948949069689599309460.0
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets2.22.22.32.42.32.42.72.72.62.60.0

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent

us-gaap:OtherAssetsNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value113511131096935877860835701541494467500468532447432386351353328330348209211234229220196194209206187205199206328360353283339365357233221
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.02.92.82.52.32.32.42.01.51.41.41.51.41.61.41.31.21.11.21.01.01.11.11.21.31.41.41.31.21.31.41.21.31.31.41.92.02.11.82.02.02.11.51.4

Dividends Payable Current

us-gaap:DividendsPayableCurrent

us-gaap:DividendsPayableCurrent


Dividends
Period End2021-06-302020-12-312019-12-312018-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value191031008758655855545555515050484748474946454646
Percentage of DividendsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.30.30.30.30.40.40.40.40.30.30.30.30.30.30.30.30.30.30.30.30.30.3

Liabilities Current

us-gaap:LiabilitiesCurrent

us-gaap:LiabilitiesCurrent


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value19174190201933219220190191862416070167361720417654153011555516382158041475514556150291458513370142171441715256128011188112495105481023210005109841027694741013510765106711019411086116491109199961082012083113581030910498
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets50.149.250.250.549.949.445.446.948.949.247.247.147.946.245.545.145.945.344.244.744.546.267.966.768.265.566.365.866.464.964.066.167.567.567.565.266.264.963.665.167.365.965.167.2

Long Term Debt Current

us-gaap:LongTermDebtCurrent

us-gaap:LongTermDebtCurrent


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1110471971973525697316484187187186
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.91.22.52.61.41.80.91.40.50.50.6

us-gaap:LongTermDebtCurrent us-gaap:DebtInstrument

wltw:SeniorNotesDue202103500


Long
Period End2021-06-302021-03-312020-12-312020-09-30
Value450450449449
Percentage of LongTermDebtCurrent40.595.546.246.1
Percentage of Assets1.21.21.21.2
Percentage of Assets wltw:SeniorNotesDue2021035000.00.00.00.0

wltw:SeniorNotesDue202105750


Long
Period End2020-12-312020-09-302020-06-302020-03-31
Value500500500499
Percentage of LongTermDebtCurrent51.551.495.271.6
Percentage of Assets1.31.31.31.3
Percentage of Assets wltw:SeniorNotesDue2021057500.00.00.00.0

wltw:SeniorNotesDue202202125


Long
Period End2021-06-30
Value640
Percentage of LongTermDebtCurrent57.7
Percentage of Assets1.7
Percentage of Assets wltw:SeniorNotesDue2022021250.0

us-gaap:LongTermDebtCurrent us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1110471971973525697316484187187186
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.91.22.52.61.41.80.91.40.50.50.6
Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure us-gaap:FairValueMeasurementsNonrecurring0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1122476985996540704319488188190191
Percentage of LongTermDebtCurrent101.1101.1101.4102.4102.9101.0100.9100.8100.5101.6102.7
Percentage of Assets2.91.22.62.61.41.90.91.40.50.50.6
Percentage of Assets us-gaap:EstimateOfFairValueFairValueDisclosure us-gaap:FairValueMeasurementsNonrecurring0.00.00.00.00.00.00.00.00.00.00.0

Operating Lease Liability Current

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OperatingLeaseLiabilityCurrent


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1521471521431441511641511541580.0
Percentage of OperatingLeaseLiabilityCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets0.40.40.40.40.40.40.50.40.40.40.0

Other Liabilities Current

us-gaap:OtherLiabilitiesCurrent

us-gaap:OtherLiabilitiesCurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value751965888811804858802801810940864758814867804793882996876812901972558488522461444445467495415381358333327289297334282274318343266278
Percentage of OtherLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.02.52.32.12.12.32.32.22.32.62.72.32.42.52.52.52.73.12.92.62.82.93.02.72.82.92.92.92.83.12.82.52.22.12.21.71.72.01.81.61.82.01.71.8

Taxes Payable Current

us-gaap:TaxesPayableCurrent

us-gaap:TaxesPayableCurrent


Taxes
Period End2021-06-302020-12-312019-12-312019-09-302018-12-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value11610213816512990179917912913645
Percentage of TaxesPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.30.40.50.40.30.60.30.20.40.40.2

Liabilities Noncurrent

us-gaap:LiabilitiesNoncurrent

us-gaap:LiabilitiesNoncurrent


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value73788038826781978635871489878936773079977087729674577578742676357301719066496630675264163625339432833185313729303105308030833141317332383193321932483296321530783119321129302898
Percentage of LiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets19.320.821.521.622.723.125.425.022.022.321.922.121.822.222.923.722.322.322.020.820.819.419.219.117.919.820.319.318.819.520.820.519.920.521.118.918.419.320.418.517.418.618.518.5

Long Term Debt

us-gaap:LongTermDebt

us-gaap:LongTermDebt


Long
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value78848017640056384943
Percentage of LongTermDebt100.0100.0100.0100.0100.0
Percentage of Assets20.522.619.817.416.3

us-gaap:LongTermDebt us-gaap:DebtInstrument

wltw:CollateralizedFacility


Long
Period End2020-12-312019-12-31
Value5579
Percentage of LongTermDebt0.71.0
Percentage of Assets0.10.2
Percentage of Assets wltw:CollateralizedFacility0.00.0

us-gaap:LongTermDebt us-gaap:DebtInstrument, us-gaap:LongtermDebtType

wltw:InterestOnSeniorNotes, us-gaap:SeniorNotes


Long
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value22192362179110781049
Percentage of LongTermDebt28.129.528.019.121.2
Percentage of Assets5.86.75.53.33.5
Percentage of Assets wltw:InterestOnSeniorNotes us-gaap:SeniorNotes0.00.00.00.00.0

us-gaap:LongTermDebt us-gaap:LongtermDebtType

us-gaap:SeniorNotes


Long
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value56105281447935063176
Percentage of LongTermDebt71.265.970.062.264.3
Percentage of Assets14.614.913.810.810.5
Percentage of Assets us-gaap:SeniorNotes0.00.00.00.00.0

Long Term Debt Noncurrent

us-gaap:LongTermDebtNoncurrent

us-gaap:LongTermDebtNoncurrent


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value39954632466446415068517753015381428445184389449845894507445044934097397533573267328127672278224820522137214221482302230723112315232623872338236423972435235422852307243221572165
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets10.412.012.112.213.313.715.015.112.212.613.613.613.413.213.713.912.512.311.110.310.18.412.112.611.213.313.914.113.914.615.615.114.615.115.513.913.614.215.013.812.914.113.613.9

Deferred Income Tax Liabilities Net

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:DeferredIncomeTaxLiabilitiesNet


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-31
Value628576561587575501526690559
Percentage of DeferredIncomeTaxLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.61.51.51.51.51.31.51.91.7

Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value1238127814051172123512611324103911251135117010871185123012591207127112861321108911601210279
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.23.33.63.13.23.33.72.93.23.23.63.33.53.63.93.73.94.04.43.43.63.71.5

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

country:GB, us-gaap:PensionPlansDefinedBenefit


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value7.07.08.09.017
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent0.50.50.70.71.3
Percentage of Assets0.00.00.00.00.1
Percentage of Assets country:GB us-gaap:PensionPlansDefinedBenefit0.00.00.00.00.0

country:US, us-gaap:PensionPlansDefinedBenefit


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value903862735782842
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent64.365.162.862.163.7
Percentage of Assets2.32.42.32.42.8
Percentage of Assets country:US us-gaap:PensionPlansDefinedBenefit0.00.00.00.00.0

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value294270253271268
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent20.920.421.621.520.3
Percentage of Assets0.80.80.80.80.9
Percentage of Assets wltw:OtherForeignPlans us-gaap:PensionPlansDefinedBenefit0.00.00.00.00.0

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Pension
Period End2020-12-312019-12-312018-12-312017-12-31
Value858481116
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent6.06.36.99.2
Percentage of Assets0.20.20.30.4
Percentage of Assets us-gaap:OtherPostretirementBenefitPlansDefinedBenefit0.00.00.00.0

Minority Interest

us-gaap:MinorityInterest

us-gaap:MinorityInterest


Minority
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-31
Value454811210512112612011411412211911411913012311112412611813413815313193962322151830282323282624242931293239314950
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.30.30.30.30.30.30.30.30.40.30.30.40.40.30.40.40.40.40.40.50.70.50.50.10.10.10.10.20.20.20.10.20.20.10.10.20.20.20.20.20.20.30.0

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OtherLiabilitiesNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value280305312322317320335314299296429448446506544476473512532544561605533502506398389347362354374353371378375376381371363362367371347294
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.80.80.80.80.80.90.90.90.81.31.41.31.51.71.51.41.61.81.71.71.82.82.82.82.52.52.32.22.22.52.32.32.42.52.22.22.22.32.22.02.22.21.9

Operating Lease Liability Noncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value8388579189159069149649579419610.0
Percentage of OperatingLeaseLiabilityNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets2.22.22.42.42.42.42.72.72.72.70.0

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo


Lessee
Period End2020-12-312019-09-302019-06-302019-03-312018-12-31
Value172182178180180
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0100.0100.0100.0100.0
Percentage of Assets0.40.50.50.50.6

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree


Lessee
Period End2020-12-312019-09-302019-06-302019-03-312018-12-31
Value157162161160159
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0100.0100.0100.0100.0
Percentage of Assets0.40.50.50.40.5

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour


Lessee
Period End2020-12-312019-09-302019-06-302019-03-312018-12-31
Value138147144142142
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0100.0100.0100.0100.0
Percentage of Assets0.40.40.40.40.4

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive


Lessee
Period End2020-12-312019-09-302019-06-302019-03-312018-12-31
Value123137134132131
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0100.0100.0100.0100.0
Percentage of Assets0.30.40.40.40.4

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive


Lessee
Period End2020-12-312019-09-302019-06-302019-03-312018-12-31
Value458624572552542
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0100.0100.0100.0100.0
Percentage of Assets1.21.71.61.51.7

Operating Lease Liability

us-gaap:OperatingLeaseLiability

us-gaap:OperatingLeaseLiability


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value107011281108109511191149
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0100.0
Percentage of Assets2.83.23.13.13.13.5

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue


Lessee
Period End2020-12-312019-09-302019-06-302019-03-312018-12-31
Value12331302128513131351
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0100.0100.0100.0100.0
Percentage of Assets3.23.63.73.74.2

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount


Lessee
Period End2020-12-312019-09-302019-06-302019-03-312018-12-31
Value163194190194202
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount100.0100.0100.0100.0100.0
Percentage of Assets0.40.50.50.50.6

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-31
Value1167011526108201051510335102631024998871009010092985210049102281067210126991510263102781006510767110501115122292393239322981985225824442442221520241977186516992674268726752486268827072630257721801845
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.529.828.127.627.127.228.927.728.728.130.430.429.931.231.230.731.331.933.333.934.133.811.813.413.114.312.914.814.815.415.013.212.411.811.215.715.315.715.816.215.115.316.314.00.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value-1915.0-1928.0-1968.0-1677.0-1686.0-1695.0-1702.0-1360.0-1363.0-1370.0-1337.0-1073.0-1094.0-1132.0-1138.0-1122.0-1152.0-707.0-710.0-711.0-713.0-660.0-680.0-663.0-893.0-714.0
Percentage of StockholdersEquity-16.4-16.7-18.2-15.9-16.3-16.5-16.6-13.8-13.5-13.6-13.6-10.7-10.7-10.6-11.2-10.9-11.4-6.6-6.4-6.4-32.0-27.6-28.4-28.9-45.0-32.2
Percentage of Assets-5.0-5.0-5.1-4.4-4.4-4.5-4.8-3.8-3.9-3.8-4.1-3.2-3.2-3.3-3.5-3.5-3.8-2.2-2.2-2.2-3.8-3.7-3.7-4.1-5.8-4.8
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-2278.0-2311.0-2359.0-2253.0-2390.0-2446.0-2227.0-2113.0-1993.0-1974.0-1961.0-1627.0-1605.0-1430.0-1513.0-1908.0-1884.0-1221.0-1181.0-1053.0-1037.0-954.0-872.0-952.0-1066.0-693.0-744.0-541.0-594.0-630.0-153.0
Percentage of StockholdersEquity-19.5-20.1-21.8-21.4-23.1-23.8-21.7-21.4-19.8-19.6-19.9-16.2-15.7-13.4-14.9-18.6-18.7-11.3-10.7-9.4-46.5-39.9-36.4-41.4-53.7-31.3-29.9-21.0-27.2-34.10.0
Percentage of Assets-6.0-6.0-6.1-5.9-6.3-6.5-6.3-5.9-5.7-5.5-6.1-4.9-4.7-4.2-4.7-5.9-6.2-3.8-3.6-3.2-5.5-5.4-4.8-5.9-6.9-4.7-4.7-3.4-3.80.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value-376.0-398.0-400.0-579.0-698.0-746.0-538.0-746.0-626.0-607.0-616.0-550.0-506.0-307.0-365.0-724.0-650.0-434.0-398.0-310.0-314.0-302.0-230.0-296.0-191.0-14.0
Percentage of StockholdersEquity-3.2-3.5-3.7-5.5-6.8-7.3-5.2-7.5-6.2-6.0-6.3-5.5-4.9-2.9-3.6-7.0-6.5-4.0-3.6-2.8-14.1-12.6-9.6-12.9-9.6-0.6
Percentage of Assets-1.0-1.0-1.0-1.5-1.8-2.0-1.5-2.1-1.8-1.7-1.9-1.7-1.5-0.9-1.1-2.2-2.1-1.4-1.2-0.9-1.7-1.7-1.3-1.8-1.2-0.1
Percentage of Assets us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312016-12-31
Value13159.03.0-6.0-5.013-7.0-4.03.0-8.0-10.0-82.0
Percentage of StockholdersEquity0.10.10.10.0-0.1-0.00.1-0.1-0.00.0-0.1-0.1-0.8
Percentage of Assets0.00.00.00.0-0.0-0.00.0-0.0-0.00.0-0.0-0.0-0.3
Percentage of Assets us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent0.00.00.00.00.00.00.00.00.00.00.00.00.0

Stockholders Equity Including Portion Attributable To Noncontrolling Interest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value11715115741093210620104561038910369100011020410214997110163103471080210249100261038710404101831090111188113042360248624892321200722732462247222432047200018931725269827112704251727172739266926082498242922291895
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.630.028.427.927.427.529.328.029.028.530.830.830.231.631.631.131.732.333.734.334.534.212.514.013.614.413.014.914.915.615.213.412.512.011.415.915.415.816.016.415.315.516.50.00.014.30.0

Additional Paid In Capital Common Stock

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:AdditionalPaidInCapitalCommonStock


Additional
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1078510765107481072410713107031068710667106441063010615105771053816721673165015841524147514431378131612581207115511251116109110721073105010331017985918
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets28.227.927.928.228.128.430.229.930.329.632.832.032.58.99.49.09.89.99.78.78.78.98.27.67.37.46.66.26.36.86.35.85.96.25.9

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value31663075243420472015200917921336144214391201110212701557110411301402156114521455173917711597167716181669153015211664175215951577165315991427227823432319216021802165212521361859
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets8.38.06.35.45.35.35.13.74.14.03.73.33.74.63.43.54.34.84.84.65.45.48.59.48.810.49.910.010.111.110.810.310.410.19.413.413.313.613.713.112.112.313.511.9

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value-2278000000.0-2311000000.0-2359000000.0-2253000000.0-2390000000.0-2446000000.0-2227000000.0-2113000000.0-1993000000.0-1974000000.0-1961000000.0-1627000000.0-1605000000.0-1430000000.0-1513000000.0-1676000000.0-1776000000.0-1908000000.0-1884000000.0-1221000000.0-1181000000.0-1053000000.0-1037000000.0-954000000.0-872000000.0-952000000.0-1066000000.0-735000000.0-660000000.0-685000000.0-693000000.0-853000000.0-720000000.0-747000000.0-715000000.0-744000000.0-539000000.0-488000000.0-509000000.0-541000000.0-594000000.0
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-6.0-6.0-6.1-5.9-6.3-6.5-6.3-5.9-5.7-5.5-6.1-4.9-4.7-4.2-4.7-5.2-5.4-5.9-6.2-3.8-3.6-3.2-5.5-5.4-4.8-5.9-6.9-4.8-4.0-4.3-4.7-5.6-4.2-4.2-4.2-4.7-3.2-2.7-3.0-3.4-3.8

Treasury Stock Value

us-gaap:TreasuryStockValue

us-gaap:TreasuryStockValue


Treasury
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value3.03.03.03.03.03.03.03.03.03.03.03.03.03.03.040213.0993.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.03.0
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.10.00.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Minority Interest

us-gaap:MinorityInterest

us-gaap:MinorityInterest


Minority
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-31
Value454811210512112612011411412211911411913012311112412611813413815313193962322151830282323282624242931293239314950
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.30.30.30.30.30.30.30.30.40.30.30.40.40.30.40.40.40.40.40.50.70.50.50.10.10.10.10.20.20.20.10.20.20.10.10.20.20.20.20.20.20.30.0

Minority Interest Decrease From Distributions To Noncontrolling Interest Holders

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders


Minority
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302018-09-302018-06-302014-09-302013-09-30
Value4.0179.0121.01.0196.0161.01.0
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Minority
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302018-09-302018-06-30
Value4.0179.0121.01.0196.016
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value494-128.056852166223461317350-47.0572321377183471963199531218130911813010671-64.01961291475.0195229983921515296621671461197.0241948569
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.0-5.020.626.131.50.917.116.117.2-2.124.117.619.20.816.710.616.34.116.210.215.95.313.312.57.7-5.920.515.915.70.521.228.811.03.724.720.211.46.120.419.213.80.728.912.810.67.1

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-55.0645-52.0141-87.0-162.0-83.0-1383.0-73.0-75.0-101.0-87.0-74.0-79.0-73.0-107.0-155.0-82.0-88.0-25.0-109.0417-595.0-100.0-240.0-8.0-159.0-35.0-61.0-21.0-15.0-30.0-54.0-21.0-73.0-33.0-29.0-37.0-29.0-20.0-28.0-24.0-18.0-19.0-16.0-41.0
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-2.425.2-1.97.1-4.1-6.7-3.1-70.3-3.6-3.3-4.3-4.8-3.8-3.5-3.5-5.8-7.9-3.5-4.6-1.4-5.618.7-61.1-11.8-26.0-0.7-16.6-4.3-6.5-1.9-1.6-3.8-6.1-2.0-8.4-4.4-3.4-3.7-3.5-2.6-3.2-2.4-2.2-2.6-2.0-4.2

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-188.0-633.0-100.0-119.0-401.0186-377.01148-456.082-361.0-207.0-311.0-24.0-233.0-50.0-196.014-116.0-331.0-200.0-115.0547-10.0143-39.0-40.0-128.0-106.0-49.0-5.0-82.0-68.018-67.0-104.0-120.00.0-64.0-69.0-208.0127-67.0-89.0-120.0-17.0
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-8.4-24.7-3.6-6.0-19.17.6-14.058.4-22.53.6-15.2-11.3-15.8-1.1-11.2-2.7-10.00.6-6.0-18.6-10.3-5.156.2-1.215.5-3.6-4.2-15.8-11.3-4.5-0.5-10.3-7.61.7-7.7-13.8-14.30.0-7.8-9.1-24.112.6-8.0-12.1-15.0-1.7

Deferred Income Tax Expense Benefit

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:DeferredIncomeTaxExpenseBenefit


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value4610.0441563-23.0-28.0-3.0-13.0-28.0-45.0-22.0-22.0-26.0-229.0180.0-74.0-124.0-64.014-70.0-28.0-104.02112
Percentage of DeferredIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Increase Decrease In Accounts Receivable

us-gaap:IncreaseDecreaseInAccountsReceivable

us-gaap:IncreaseDecreaseInAccountsReceivable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-76.0115287-231.0-174.046454-275.0-39.0121264-251.0-124.04395-205.0-79.0253121-143.0-38.0161100-105.08.015235-106.0-3.014060-68.0-4.012825-119.0318012-108.049139-8.0-76.04277
Percentage of IncreaseDecreaseInAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value494-128.056852166223461317350-47.0572321377183471963199531218130911813010671-64.01961291475.0195229983921515296621671461197.0241948569
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.0-5.020.626.131.50.917.116.117.2-2.124.117.619.20.816.710.616.34.116.210.215.95.313.312.57.7-5.920.515.915.70.521.228.811.03.724.720.211.46.120.419.213.80.728.912.810.67.1

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value18473347612194305544751382873784458215245-54.033344142-32.072238-24.01177021076-7.04724668-27.0105219-805.02610822525608534986489204
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.228.617.36.14.512.520.23.86.812.615.92.43.09.511.8-2.91.714.87.4-1.83.710.7-2.513.87.619.37.9-0.95.022.47.4-3.411.820.8-92.43.412.822.23.17.99.83.411.88.711.121.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value186736483122102313551801492933834665221253-54.041352148-31.076245-18.01167221483-8.04825074-27.0107223-801.026110232296089421036591211
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.328.717.66.14.912.920.54.17.312.816.12.53.39.712.2-2.92.115.27.7-1.73.911.0-1.813.77.819.78.7-1.05.122.88.1-3.412.021.2-92.03.413.122.93.57.910.34.212.48.911.421.7

Share Based Compensation

us-gaap:ShareBasedCompensation

us-gaap:ShareBasedCompensation


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2527313129-1.026211710.035111.03.019151914292633351812161810.01414141110.09.0128.07.08.09.08.09.010.014139.01312
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-55.0645-52.0141-87.0-162.0-83.0-1383.0-73.0-75.0-101.0-87.0-74.0-79.0-73.0-107.0-155.0-82.0-88.0-25.0-109.0417-595.0-100.0-240.0-8.0-159.0-35.0-61.0-21.0-15.0-30.0-54.0-21.0-73.0-33.0-29.0-37.0-29.0-20.0-28.0-24.0-18.0-19.0-16.0-41.0
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-2.425.2-1.97.1-4.1-6.7-3.1-70.3-3.6-3.3-4.3-4.8-3.8-3.5-3.5-5.8-7.9-3.5-4.6-1.4-5.618.7-61.1-11.8-26.0-0.7-16.6-4.3-6.5-1.9-1.6-3.8-6.1-2.0-8.4-4.4-3.4-3.7-3.5-2.6-3.2-2.4-2.2-2.6-2.0-4.2

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-188.0-633.0-100.0-119.0-401.0186-377.01148-456.082-361.0-207.0-311.0-24.0-233.0-50.0-196.014-116.0-331.0-200.0-115.0547-10.0143-39.0-40.0-128.0-106.0-49.0-5.0-82.0-68.018-67.0-104.0-120.00.0-64.0-69.0-208.0127-67.0-89.0-120.0-17.0
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-8.4-24.7-3.6-6.0-19.17.6-14.058.4-22.53.6-15.2-11.3-15.8-1.1-11.2-2.7-10.00.6-6.0-18.6-10.3-5.156.2-1.215.5-3.6-4.2-15.8-11.3-4.5-0.5-10.3-7.61.7-7.7-13.8-14.30.0-7.8-9.1-24.112.6-8.0-12.1-15.0-1.7

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt


Repayments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value7.05088.08.01831281708222.01.00.012722212019695636403564511817.01514.04.0
Percentage of RepaymentsOfLongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Payments Of Dividends Common Stock

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:PaymentsOfDividendsCommonStock


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value177928788878484848477787981686872137656666670.01125655545354535049494847464647464446454544434544
Percentage of PaymentsOfDividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Effective Income Tax Rate Continuing Operations

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:EffectiveIncomeTaxRateContinuingOperations


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value33.811.527.60.4220.20.2040.1970.188-0.2810.1270.163-0.530.1680.1160.4590.2060.069-0.330.20.22-0.20.540.21-0.730.210.190.260.250.240.040.250.04
Percentage of EffectiveIncomeTaxRateContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber

us-gaap:PerformanceShares


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value0.30.30.30.30.30.30.30.30.30.40.50.60.60.60.71.01.01.10.91.21.21.30.70.81.2
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:PerformanceBasedStockOptions


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value0.2840.2870.5420.680.8830.6171.3842.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber94.795.7108.497.198.10.00.00.0

wltw:TimeBasedShares


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.10.10.10.30.20.20.30.30.40.30.40.50.60.70.80.90.91.01.21.31.91.5
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber33.333.333.3100.066.766.7100.0100.0133.375.080.083.3100.0116.7114.390.090.090.9133.3108.3158.3115.4

wltw:TimeBasedStockOptions


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value0.0850.260.4490.7541.21.5982.1453.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber28.386.789.8107.7133.30.00.00.0

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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

wltw:PerformanceBasedStockOptions


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value110.58110.58110.55106.42101.9588.6589.49
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0

wltw:TimeBasedStockOptions


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value114.92104.38101.21105.47101.11103.6299.19
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice103.994.491.699.199.2116.9110.8

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value466454500678691569814164274246238322256
Percentage of DeferredTaxLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsNet


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value875885607592894299146187230330207
Percentage of DeferredTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsNet us-gaap:BalanceSheetLocation

us-gaap:OtherNoncurrentAssets


Deferred
Period End2020-12-312019-12-31
Value9572
Percentage of DeferredTaxAssetsNet10.98.1

Unrecognized Tax Benefits

us-gaap:UnrecognizedTaxBenefits

us-gaap:UnrecognizedTaxBenefits


Unrecognized
Period End2020-12-312019-12-312018-12-312018-06-302017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value5049495359562219413716131733
Percentage of UnrecognizedTaxBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Valuation Allowance

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:DeferredTaxAssetsValuationAllowance


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value847681162134187280196221102879285
Percentage of DeferredTaxAssetsValuationAllowance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Litigation Reserve Current

us-gaap:LitigationReserveCurrent

us-gaap:LitigationReserveCurrent


Litigation
Period End2020-12-31
Value210
Percentage of LitigationReserveCurrent100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value251-116.0416543174471.082-179.0-40.0110
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStockDividendsPerShareDeclared

us-gaap:CommonStockDividendsPerShareDeclared


Common
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.710.710.680.680.680.650.650.650.60.60.60.530.530.530.530.480.480.480.482.350.310.310.310.30.30.30.30.280.280.280.280.270.270.270.270.260.260.260.260.260.260.260.26
Percentage of CommonStockDividendsPerShareDeclared100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiabilityRevenueRecognized wltw:BalanceSheetDate

us-gaap:ContractWithCustomerLiabilityRevenueRecognized

wltw:December312019


Contract
Period End2020-12-312020-09-302020-06-30
Value5045130
Percentage of ContractWithCustomerLiabilityRevenueRecognized100.0100.0100.0

wltw:December312020


Contract
Period End2021-06-302021-03-31
Value94275
Percentage of ContractWithCustomerLiabilityRevenueRecognized0.00.0

wltw:June302020


Contract
Period End2020-09-30
Value211
Percentage of ContractWithCustomerLiabilityRevenueRecognized468.9

wltw:March312021


Contract
Period End2021-06-30
Value261
Percentage of ContractWithCustomerLiabilityRevenueRecognized0.0

us-gaap:ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod

us-gaap:ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-09-302019-06-30
Value17235.0155.03.09.0
Percentage of ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredForeignIncomeTaxExpenseBenefit us-gaap:IncomeTaxAuthorityName

us-gaap:DeferredForeignIncomeTaxExpenseBenefit

us-gaap:HerMajestysRevenueAndCustomsHMRC


Deferred
Period End2021-06-302020-09-30
Value4011
Percentage of DeferredForeignIncomeTaxExpenseBenefit100.0100.0

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-7.07.0-6.0-6.0-5.0-6.0-6.0-5.0-5.0-5.0-11.0-10.0-12.0-12.0-14.0-13.0-13.0-13.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-11.011-9.0-9.0-8.0-9.0-5.0-4.0-5.0-5.0-2.0-3.0-3.0-3.0-3.0-4.0-3.0-3.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses157.1157.1150.0150.0160.0150.083.380.0100.0100.018.230.025.025.021.430.823.123.1

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-2.01.0-1.00.0-2.00.00.0-1.00.0-1.0-1.00.0-1.00.0-1.00.0-1.00.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses28.614.316.7-0.040.0-0.0-0.020.0-0.020.09.1-0.08.3-0.07.1-0.07.7-0.0

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-1.00.00.0-1.00.00.0-1.00.00.01.0-1.00.00.00.00.00.00.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses14.3-0.0-0.020.0-0.0-0.020.0-0.0-0.0-9.110.0-0.0-0.0-0.0-0.0-0.0-0.0

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-5.0-4.0-5.0-4.0-4.0-4.0-4.0-4.0-4.0-4.0-5.0-4.0-5.0-5.0-5.0-4.0-4.0-5.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-1.0-1.0-1.0-1.0-1.0-1.0-1.0-1.0-1.0-1.00.00.00.00.00.00.00.00.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit20.025.020.025.025.025.025.025.025.025.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0

us-gaap:DefinedBenefitPlanContributionsByEmployer us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanContributionsByEmployer

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value9.010.0161515202317191824173113
Percentage of DefinedBenefitPlanContributionsByEmployer100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.06031400.00.029600.00.038500.00.0
Percentage of DefinedBenefitPlanContributionsByEmployer0.0600.0193.8266.70.00.0126.1352.90.00.0158.3294.10.00.0

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3.016153.03.014112.03.015114.03.04.0
Percentage of DefinedBenefitPlanContributionsByEmployer33.3160.093.820.020.070.047.811.815.883.345.823.59.730.8

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value434363635962625962637172777873727168
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value777773737273646363646868696861616261
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets179.1179.1115.9115.9122.0117.7103.2106.8101.6101.695.894.489.687.283.684.787.389.7

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value10.09.09.08.09.08.07.07.08.07.08.08.07.08.08.07.08.07.0
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets23.320.914.312.715.312.911.311.912.911.111.311.19.110.311.09.711.310.3

us-gaap:DefinedBenefitPlanInterestCost us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanInterestCost

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value141419181818232323242324242424232422
Percentage of DefinedBenefitPlanInterestCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value242333323333393939403535353535343535
Percentage of DefinedBenefitPlanInterestCost171.4164.3173.7177.8183.3183.3169.6169.6169.6166.7152.2145.8145.8145.8145.8147.8145.8159.1

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value3.03.04.04.03.04.04.05.05.04.05.04.04.05.04.04.05.04.0
Percentage of DefinedBenefitPlanInterestCost21.421.421.122.216.722.217.421.721.716.721.716.716.720.816.717.420.818.2

us-gaap:DefinedBenefitPlanInterestCost us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.00.01.00.01.01.00.01.01.01.01.01.01.01.01.01.01.0
Percentage of DefinedBenefitPlanInterestCost7.10.05.60.05.64.30.04.34.24.34.24.24.24.24.34.24.5

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-21.0-22.0-37.0-39.0-36.0-38.0-33.0-32.0-35.0-34.0-29.0-26.0-21.0-42.06.0-32.0-31.0-30.0
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-22.0-22.0-13.0-14.0-11.0-13.0-4.0-3.0-3.0-3.0-14.0-13.0-14.0-14.0-6.0-6.0-7.0-7.0
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost104.8100.035.135.930.634.212.19.48.68.848.350.066.733.3-100.018.822.623.3

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.01.03.01.01.01.02.05.02.03.03.0-12.03.02.03.03.02.02.0
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost-4.8-4.5-8.1-2.6-2.8-2.6-6.1-15.6-5.7-8.8-10.346.2-14.3-4.850.0-9.4-6.5-6.7

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.0-1.00.00.01.00.00.00.01.02.01.01.01.01.01.01.0
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost-4.84.5-0.0-0.0-3.0-0.0-0.0-0.0-3.4-7.7-4.8-2.416.7-3.1-3.2-3.3

us-gaap:DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1 us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302020-12-312020-09-302020-06-302019-06-302018-12-312018-09-302018-06-302017-12-312017-09-302017-06-30
Value-1.0-2.00.0-1.00.0-9.0-12.0-20.0-37.00.00.0
Percentage of DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1100.0100.00.0100.00.0100.0100.0100.0100.00.00.0

country:US, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-06-302018-12-312018-09-302018-06-302017-12-312017-09-302017-06-30
Value-2.01.00.00.0-2.00.0-1.00.00.00.0-1.00.0
Percentage of DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1200.00.0-0.00.0200.00.011.1-0.0-0.0-0.00.00.0

us-gaap:DefinedBenefitPlanServiceCost us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanServiceCost

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value5.04.04.04.03.04.04.03.03.04.04.04.05.05.09.08.07.08.0
Percentage of DefinedBenefitPlanServiceCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value202018181818161716161617171617161716
Percentage of DefinedBenefitPlanServiceCost400.0500.0450.0450.0600.0450.0400.0566.7533.3400.0400.0425.0340.0320.0188.9200.0242.9200.0

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value6.06.06.05.05.05.05.05.05.05.05.06.05.05.05.06.04.05.0
Percentage of DefinedBenefitPlanServiceCost120.0150.0150.0125.0166.7125.0125.0166.7166.7125.0125.0150.0100.0100.055.675.057.162.5

us-gaap:DefinedContributionPlanEmployerDiscretionaryContributionAmount

us-gaap:DefinedContributionPlanEmployerDiscretionaryContributionAmount


Defined
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value3943394043373741284148393742374036-42.0201914
Percentage of DefinedContributionPlanEmployerDiscretionaryContributionAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Depreciation

us-gaap:Depreciation


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value727170736798695859545554535110154514646454443252523222223242326212126202119191817192018141615
Percentage of Depreciation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred

us-gaap:DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred


Derivative
Period End2021-06-302021-03-312020-12-31
Value-2000000.06000000.08000000.0
Percentage of DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred100.0100.0100.0

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet

us-gaap:ForeignExchangeContract, us-gaap:CashFlowHedging, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value3.01.0-1.0-4.0-2.0-2.0-1.0-2.0-2.0-4.0-4.0-6.0-7.0-11.00.0-10.0-20.0-23.0-14.0-14.0-8.0-4.0
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation

us-gaap:ForeignExchangeContract, us-gaap:CashFlowHedging, us-gaap:DesignatedAsHedgingInstrument, wltw:Revenue


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-31
Value0.0-2.0-2.0-2.0-1.0-2.0-1.0-3.01.0
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet0.0-200.0200.050.050.0200.050.0150.0-25.0

us-gaap:ForeignExchangeContract, us-gaap:CashFlowHedging, us-gaap:DesignatedAsHedgingInstrument, wltw:SalariesAndBenefits


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value3.03.01.0-2.0-1.0-2.01.0-1.01.0-5.0
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet100.0300.0-100.050.050.0100.0-100.050.0-50.0125.0

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

us-gaap:DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet

us-gaap:ForeignExchangeContract, us-gaap:Nondesignated, us-gaap:OtherExpense


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value-13.0-16.0125.0-8.0-12.0166.06.0-10.04.0-1.02.0-5.05.0-3.01.08.03.04.00.0
Percentage of DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:DividendsCommonStock

us-gaap:DividendsCommonStock


Dividends
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value93928988888584858692796874817768707264
Percentage of DividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStock us-gaap:StatementEquityComponents

us-gaap:Parent


Dividends
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value93928988888584858076796871707667686664
Percentage of DividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.093.082.6100.0100.095.986.498.798.597.191.7100.0

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value93928988888584858076796871707667686664
Percentage of DividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.093.082.6100.0100.095.986.498.798.597.191.7100.0

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Effect
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value4.0-14.0261714-36.020-20.0-1.0-1.0-8.0
Percentage of EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings


Fair
Period End2020-12-31
Value13
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases


Fair
Period End2020-12-31
Value0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases0.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements


Fair
Period End2021-06-302021-03-31
Value0.017
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements0.0100.0

us-gaap:FinanceLeaseInterestExpense

us-gaap:FinanceLeaseInterestExpense


Finance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value01000000.01000000.001000000.01000000.001000000.01000000.01000000.0
Percentage of FinanceLeaseInterestExpense0.0100.0100.00.0100.0100.00.0100.0100.0100.0

us-gaap:FinanceLeaseRightOfUseAssetAmortization

us-gaap:FinanceLeaseRightOfUseAssetAmortization


Finance
Period End2021-06-302020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1000000.001000000.001000000.001000000.001000000.0
Percentage of FinanceLeaseRightOfUseAssetAmortization100.00.0100.00.0100.00.0100.00.0100.0

us-gaap:FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss

us-gaap:FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss


Finite
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-6.08.072-43.038-29.0-4.03.0-20.0-4.0-61.025-246.040611772171623
Percentage of FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-5.010.0-30.0-22.066-40.028-19.0-4.03.0-19.0-2.0-44.018-186.03145135610.04.019
Percentage of FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss83.3125.00.00.091.793.073.765.5100.0100.095.050.072.172.075.677.573.876.577.858.825.082.6

us-gaap:OtherIntangibleAssets


Finite
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.0-2.00.0-1.03.0-3.0-1.01.0-1.00.00.0-1.01.00.00.0-1.0-1.01.0
Percentage of FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss-0.0-25.00.00.04.27.05.0-25.01.60.0-0.0-2.51.60.00.0-5.9-6.24.3

us-gaap:SoftwareAndSoftwareDevelopmentCosts


Finite
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-31
Value-2.0-4.03.00.01.0-1.0-2.02.0-1.0-1.0-8.05.03.05.08.01.07.09.01.0
Percentage of FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss0.00.04.2-0.02.63.450.066.75.025.013.120.0-1.212.513.15.941.256.24.3

us-gaap:TrademarksAndTradeNames


Finite
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.0-2.00.00.03.0-3.00.00.01.0-2.0-3.02.0-10.01.02.02.02.00.00.01.0
Percentage of FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss0.00.00.0-0.07.910.3-0.00.0-5.050.04.98.04.12.53.311.82.80.00.04.3

us-gaap:FinitelivedIntangibleAssetsAcquired1

us-gaap:FinitelivedIntangibleAssetsAcquired1


Finitelived
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.0114.0461.06560.03.0360.03.00.01.01.01.0479.079-156.04021
Percentage of FinitelivedIntangibleAssetsAcquired1100.0100.0100.0100.0100.0100.00.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinitelivedIntangibleAssetsAcquired1 us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships


Finitelived
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.011-5.0231.06220.03.0360.03.00.00.01.01.011-2.071-78.02231
Percentage of FinitelivedIntangibleAssetsAcquired1100.0100.0-125.050.0100.094.80.0100.0100.00.0100.00.00.0100.0100.023.4-22.289.950.055.5

us-gaap:OtherIntangibleAssets


Finitelived
Period End2020-12-312020-09-302020-06-302020-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.00.09.0230.00.00.00.00.00.00.00.00.00.0-1.01.0
Percentage of FinitelivedIntangibleAssetsAcquired10.00.0225.050.00.00.00.00.00.00.00.00.00.00.00.60.0

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax


Foreign
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value2.02.0-4.0-2.00.012-10.0-3.0-5.0-8.0-3.0-8.02.0-17.02.0-92.02.0115.01.027-5.0-39.0-14.021-41.0
Percentage of ForeignCurrencyTransactionGainLossBeforeTax100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ForeignCurrencyTransactionGainLossRealized

us-gaap:ForeignCurrencyTransactionGainLossRealized


Foreign
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value2.02.0-4.0-2.00.012-10.0-3.0-3.0-3.016-10.05.0-9.09.03.05.05.04.06.0
Percentage of ForeignCurrencyTransactionGainLossRealized100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnContractTermination us-gaap:BusinessAcquisition, us-gaap:RestructuringCostAndReserve, us-gaap:SubsequentEventType

us-gaap:GainLossOnContractTermination

wltw:TerminationOfProposedCombinationWithAONPlc, us-gaap:ContractTermination, us-gaap:SubsequentEvent


Gain
Period End2021-07-26
Value1000
Percentage of GainLossOnContractTermination100.0

us-gaap:GainLossOnSaleOfBusiness

us-gaap:GainLossOnSaleOfBusiness


Gain
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value-2.0359-2.085-2.00.00.00.00.00.00.0-9.023-10.00.00.00.0
Percentage of GainLossOnSaleOfBusiness100.0100.0100.0100.0100.00.00.00.00.00.00.0100.0100.0100.00.00.00.0

us-gaap:GainLossOnSaleOfBusiness us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:IncomeStatementLocation

wltw:MaxMatthiessen, us-gaap:OtherIncome


Gain
Period End2020-09-30
Value86
Percentage of GainLossOnSaleOfBusiness101.2

us-gaap:GainLossOnSaleOfBusiness us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:OtherComprehensiveIncomeLocation

wltw:MaxMatthiessen, us-gaap:OtherIncome


Gain
Period End2020-09-30
Value86
Percentage of GainLossOnSaleOfBusiness101.2

wltw:Miller, us-gaap:OtherIncome


Gain
Period End2021-03-01
Value356
Percentage of GainLossOnSaleOfBusiness0.0

us-gaap:GoodwillForeignCurrencyTranslationGainLoss

us-gaap:GoodwillForeignCurrencyTranslationGainLoss


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-9.030-68.0-66.0103-68.066-59.00.0-9.0-25.0-11.0-87.03622516721-121.01.0-29.039
Percentage of GoodwillForeignCurrencyTranslationGainLoss100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GoodwillForeignCurrencyTranslationGainLoss us-gaap:StatementBusinessSegments

wltw:CorporateRiskAndBroking


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-4.016-26.0-23.030-21.025-24.03.0-7.0-9.0
Percentage of GoodwillForeignCurrencyTranslationGainLoss44.453.338.234.829.130.937.940.70.077.836.0

wltw:HumanCapitalAndBenefits


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-5.017-30.0-28.040-27.031-28.01.0-6.0-11.0
Percentage of GoodwillForeignCurrencyTranslationGainLoss55.656.744.142.438.839.747.047.50.066.744.0

wltw:InvestmentRiskAndReinsurance


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.0-3.0-12.0-15.033-20.010.0-7.0-4.04.0-5.0
Percentage of GoodwillForeignCurrencyTranslationGainLoss-0.0-10.017.622.732.029.415.211.90.0-44.420.0

us-gaap:GoodwillPurchaseAccountingAdjustments

us-gaap:GoodwillPurchaseAccountingAdjustments


Goodwill
Period End2020-12-312020-09-302020-06-302020-03-312019-09-302017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312014-09-30
Value0.0-4.00.0-5.00.00.00.00.0-1.08.0-3.02.00.00.01.00.0
Percentage of GoodwillPurchaseAccountingAdjustments0.0100.00.0100.00.00.00.00.0100.0100.0100.0100.00.00.0100.00.0

us-gaap:GoodwillPurchaseAccountingAdjustments us-gaap:StatementBusinessSegments

wltw:BenefitsDeliveryAndAdministration


Goodwill
Period End2020-12-312020-09-302020-06-302020-03-312019-09-30
Value0.0-4.00.0-5.00.0
Percentage of GoodwillPurchaseAccountingAdjustments0.0100.00.0100.00.0

us-gaap:GoodwillWrittenOffRelatedToSaleOfBusinessUnit

us-gaap:GoodwillWrittenOffRelatedToSaleOfBusinessUnit


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.01880.01290.02.00.00.00.05.0320.00.00.05.00.01.06.06.0331.010.04.0
Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessUnit0.0100.00.0100.00.0100.00.00.00.0100.0100.00.00.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GoodwillWrittenOffRelatedToSaleOfBusinessUnit us-gaap:StatementBusinessSegments

wltw:CorporateRiskAndBroking


Goodwill
Period End2020-12-312020-09-302019-12-312019-09-302018-12-31
Value0.00.00.02.00.0
Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessUnit0.00.00.0100.00.0

wltw:HumanCapitalAndBenefits


Goodwill
Period End2020-12-312020-09-302019-12-312019-09-302018-12-31
Value0.0120.00.00.0
Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessUnit0.09.30.00.00.0

wltw:InvestmentRiskAndReinsurance


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312019-09-302018-12-31
Value0.01880.01170.00.00.0
Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessUnit0.0100.00.090.70.00.00.0

us-gaap:IncomeLossFromEquityMethodInvestments

us-gaap:IncomeLossFromEquityMethodInvestments


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2.02.02.0-1.03.02.03.01.01.00.01.01.00.01.00.01.0-6.03.0-2.016-5.03.0-3.019-11.0-1.0-3.015-7.0-2.0-1.015-11.010.0-3.016-4.09.0-2.020
Percentage of IncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingAssets

us-gaap:IncreaseDecreaseInOtherOperatingAssets


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value7615127160-75.0-7.0-133.023812737-30.0122-24.0-46.033-121.015462226924118-9.024-58.048-4.0250.0-35.0174.0-35.0133.07.0-119.017-27.0172172-16.0-21.0131
Percentage of IncreaseDecreaseInOtherOperatingAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value50-556.043220065-482.032-11.094-379.0320-15.068-393.0300-278.036-109.0222-7.027-81.0239405915716146331921518072142232-56.0-35.074-16.0-37.0-64.085162-124.0-32.054
Percentage of IncreaseDecreaseInOtherOperatingLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestAndOtherIncome

us-gaap:InterestAndOtherIncome


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value41281210.012323123182625332418
Percentage of InterestAndOtherIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestAndOtherIncome us-gaap:StatementBusinessSegments

us-gaap:CorporateNonSegment


Interest
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
Value1.01.01.01.00.01.01.01.0-2.01.03.01.0
Percentage of InterestAndOtherIncome8.310.08.33.10.04.35.63.8-8.03.012.55.6

wltw:BenefitsDeliveryAndAdministration


Interest
Period End2021-06-302021-03-31
Value0.03.0
Percentage of InterestAndOtherIncome0.010.7

wltw:CorporateRiskAndBroking


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value35208.06.07.01816147.09.08.0167.06.0
Percentage of InterestAndOtherIncome85.471.466.760.058.356.251.660.938.934.632.048.529.233.3

wltw:HumanCapitalAndBenefits


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3.03.03.02.02.010.09.03.05.06.010.05.05.04.0
Percentage of InterestAndOtherIncome7.310.725.020.016.731.229.013.027.823.140.015.220.822.2

wltw:InvestmentRiskAndReinsurance


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2.01.00.01.02.03.06.05.05.010.09.0119.07.0
Percentage of InterestAndOtherIncome4.93.60.010.016.79.419.421.727.838.536.033.337.538.9

us-gaap:LaborAndRelatedExpense

us-gaap:LaborAndRelatedExpense


Labor
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1407152314191331136313941340128312781348123312381275137712611145114811911127111912011196608570561567600569575570569541529568967502500506507490506584469462456486
Percentage of LaborAndRelatedExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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
Value55555555555456586059
Percentage of LeaseCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LitigationSettlementAmountAwardedToOtherParty us-gaap:CounterpartyName, us-gaap:LitigationStatus, us-gaap:LossContingenciesByNatureOfContingency

us-gaap:LitigationSettlementAmountAwardedToOtherParty

wltw:DelawareAction, us-gaap:SettledLitigation, wltw:WillisTowersWatsonMergerRelatedSecuritiesLitigation


Litigation
Period End2020-11-19
Value15
Percentage of LitigationSettlementAmountAwardedToOtherParty100.0

wltw:FederalAction, us-gaap:SettledLitigation, wltw:WillisTowersWatsonMergerRelatedSecuritiesLitigation


Litigation
Period End2020-11-19
Value75
Percentage of LitigationSettlementAmountAwardedToOtherParty500.0

us-gaap:LitigationSettlementAmountAwardedToOtherParty us-gaap:CounterpartyName, us-gaap:LitigationStatus, us-gaap:SubsequentEventType

wltw:StanfordFinancialGroup, us-gaap:SettledLitigation, us-gaap:SubsequentEvent


Litigation
Period End2021-01-12
Value120
Percentage of LitigationSettlementAmountAwardedToOtherParty0.0

us-gaap:LitigationSettlementAmountAwardedToOtherParty us-gaap:LitigationStatus, us-gaap:LossContingenciesByNatureOfContingency

us-gaap:SettledLitigation, wltw:WillisTowersWatsonMergerRelatedSecuritiesLitigation


Litigation
Period End2021-02-28
Value90
Percentage of LitigationSettlementAmountAwardedToOtherParty0.0

us-gaap:LitigationSettlementAmountAwardedToOtherParty us-gaap:LitigationStatus, us-gaap:LossContingenciesByNatureOfContingency, us-gaap:SubsequentEventType

us-gaap:SettledLitigation, wltw:WillisTowersWatsonMergerRelatedSecuritiesLitigation, us-gaap:SubsequentEvent


Litigation
Period End2021-01-15
Value90
Percentage of LitigationSettlementAmountAwardedToOtherParty0.0

us-gaap:LossContingencyAccrualProvision us-gaap:LitigationStatus, us-gaap:LossContingenciesByNatureOfContingency

us-gaap:LossContingencyAccrualProvision

us-gaap:SettledLitigation, wltw:WillisTowersWatsonMergerRelatedSecuritiesLitigation


Loss
Period End2020-12-31
Value50
Percentage of LossContingencyAccrualProvision100.0

us-gaap:LossContingencyAccrualProvision us-gaap:LossContingenciesByNatureOfContingency

wltw:WillisTowersWatsonMergerRelatedSecuritiesLitigation


Loss
Period End2020-09-30
Value15
Percentage of LossContingencyAccrualProvision0.0

us-gaap:NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest

us-gaap:NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest


Net
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value186736122102313781472914563221260-56.036352154-33.073244-16.011572213
Percentage of NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Net
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value2.03.01.08.08.03.09.04.01.05.06.07.0-2.03.08.05.0-1.01.06.05.0-2.02.03.0
Percentage of NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest1.10.40.87.82.63.86.11.42.27.92.72.73.68.32.33.23.01.42.5-31.2-1.72.81.4

us-gaap:Parent


Net
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value18473312194305751382874458215245-54.033344142-32.072238-24.011770210
Percentage of NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest98.999.699.292.297.496.293.998.697.892.197.394.296.491.797.792.297.098.697.5150.0101.797.298.6

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value18473312194305751382874458215245-54.033344142-32.072238-24.011770210
Percentage of NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest98.999.699.292.297.496.293.998.697.892.197.394.296.491.797.792.297.098.697.5150.0101.797.298.6

us-gaap:NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent

us-gaap:NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value-72000000.0-76000000.0-77000000.0-76000000.0-75000000.0-76000000.0-59000000.0-57000000.0
Percentage of NetPeriodicDefinedBenefitsExpenseReversalOfExpenseExcludingServiceCostComponent100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:NoncontrollingInterestDecreaseFromDeconsolidation

us-gaap:NoncontrollingInterestDecreaseFromDeconsolidation


Noncontrolling
Period End2020-09-302020-06-30
Value2.01.0
Percentage of NoncontrollingInterestDecreaseFromDeconsolidation100.0100.0

us-gaap:NoncontrollingInterestDecreaseFromDeconsolidation us-gaap:StatementEquityComponents

us-gaap:CommonStockIncludingAdditionalPaidInCapital


Noncontrolling
Period End2020-09-30
Value-7.0
Percentage of NoncontrollingInterestDecreaseFromDeconsolidation-350.0

us-gaap:NoncontrollingInterest


Noncontrolling
Period End2020-09-302020-06-30
Value9.01.0
Percentage of NoncontrollingInterestDecreaseFromDeconsolidation450.0100.0

us-gaap:Parent


Noncontrolling
Period End2020-09-30
Value-7.0
Percentage of NoncontrollingInterestDecreaseFromDeconsolidation-350.0

us-gaap:OciBeforeReclassificationsNetOfTaxAttributableToParent us-gaap:StatementEquityComponents

us-gaap:OciBeforeReclassificationsNetOfTaxAttributableToParent

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Oci
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-1.01.0-300.00.06.0-4.0-348.01.03.01.0-287.01235-1.0-65.0-5.02420-457.0-6.0-14.0-6.0-54.012-22.0222
Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedOtherComprehensiveIncome


Oci
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value22-34.0-116.012451-231.0-122.0-124.0-23.016-360.0-36.0-184.06615279109-53.0-43.0-138.0-21.0-94.076106
Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent-2200.0-3400.038.70.0850.05775.035.1-12400.0-766.71600.0125.4-300.0-525.7-6600.0-233.8-1580.0454.2-265.0716.7985.7350.0-783.3-345.547.7

us-gaap:AccumulatedTranslationAdjustment


Oci
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value22-42.017911948-208.0208-120.0-19.09.0-66.0-44.0-199.0582047877-74.0-216.0-36.0-88.04.0-12.0-72.066-105.0
Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent-2200.0-4200.0-59.70.0800.05200.0-59.8-12000.0-633.3900.023.0-366.7-568.6-5800.0-313.8-1560.0320.8-370.047.3600.0628.6-66.722.2-600.0-300.0-47.3

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Oci
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1.07.05.05.0-3.0-19.018-5.0-7.06.0
Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent-100.0700.0-1.70.0-50.0475.0-5.2-500.0-233.3600.0

us-gaap:OperatingLeaseCost

us-gaap:OperatingLeaseCost


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value45464345464752454648
Percentage of OperatingLeaseCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax

wltw:Miller


Other
Period End2021-06-302021-03-31
Value0-44000000.0
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationReclassificationAdjustmentFromAOCIRealizedUponSaleOrLiquidationNetOfTax0.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1340-291.09.09.07.0-306.03.07.0-33.0-264.021386.0-53.05.03230-445.03.01.02.0-53.020-17.0230
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value3348-106.013756-219.0-78.0-120.0-19.0-13.0-334.0-22.0-175.083163100132-24.0-40.0-128.0-16.0-82.080114
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent253.8120.036.41522.2622.2-3128.625.5-4000.0-271.439.4126.5-104.8-460.51383.3-307.52000.0412.5-80.0-1333.3-12800.0-800.0-410.0-470.649.6

us-gaap:AccumulatedTranslationAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value222.017911948-208.0208-120.0-19.09.0-66.0-44.0-199.0582047877-74.0-216.0-36.0-88.04.0-12.0-72.066-105.0
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent169.25.0-61.51322.2533.3-2971.4-68.0-4000.0-271.4-27.325.0-209.5-523.7966.7-384.91560.0240.6-246.748.5-1200.0-8800.0200.022.6-360.0-388.2-45.7

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-2.06.06.09.0-1.0-18.020-3.0-7.011
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent-15.415.0-2.1100.0-11.1-257.1-6.5-100.0-100.0-33.3

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax

wltw:Miller


Other
Period End2021-06-302021-03-31
Value0.031
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax0.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax

us-gaap:ForeignExchangeContract, us-gaap:CashFlowHedging, us-gaap:DesignatedAsHedgingInstrument


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1.04.0346.0-3.0-24.025-8.0-10.08.0-8.0-5.0-24.0151512
Percentage of OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherCostAndExpenseOperating

us-gaap:OtherCostAndExpenseOperating


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value398417505382387484472417412418434374406423376366391401380370373431283177179160165156173165161144155156150146129156192147164153153129135149
Percentage of OtherCostAndExpenseOperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherNoncashIncomeExpense

us-gaap:OtherNoncashIncomeExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-12.024202222-23.0-28.05.010.0-4.0-3.0-2.0-11.08.03654-24.0-9.0-12.01.0-16.00.0-5.0-16.07.022
Percentage of OtherNoncashIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0

us-gaap:OtherOperatingIncomeExpenseNet us-gaap:ConsolidationItems

us-gaap:OtherOperatingIncomeExpenseNet

us-gaap:MaterialReconcilingItems


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-87.0-100.0-107.0-84.0-109.0-116.0-57.0-74.0-58.0-70.0-88.0-62.0-46.0-104.0-46.0-39.0-50.0-95.0
Percentage of OtherOperatingIncomeExpenseNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsForProceedsFromOtherInvestingActivities


Payments
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-5.05.02.015-9.00.06.00.01.03.0-17.00.05.08.0-9.0-7.0-1.0-21.0-7.06.0-16.027-10.0-17.0
Percentage of PaymentsForProceedsFromOtherInvestingActivities100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsOfDebtIssuanceCosts

us-gaap:PaymentsOfDebtIssuanceCosts


Payments
Period End2020-12-312020-09-302019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-312011-09-302011-06-302011-03-31
Value0.00.00.0130.08.00.00.00.00.09.03.00.00.0140.04.00.00.01.00.00.01.02.00.08.00.00.00.05.00.01.06.0
Percentage of PaymentsOfDebtIssuanceCosts0.00.00.0100.00.0100.00.00.00.00.0100.0100.00.00.0100.00.0100.00.00.0100.00.00.0100.0100.00.0100.00.00.00.0100.00.0100.0100.0

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation


Payments
Period End2020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.0131.02.0120.00.00.0237.04.0113.03.00.04.08.01.0
Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation0.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0

us-gaap:PaymentsToAcquireBusinessesGross us-gaap:BusinessAcquisition

us-gaap:PaymentsToAcquireBusinessesGross

wltw:OtherAcquisitions


Payments
Period End2020-12-312020-09-302020-06-302020-03-312019-12-31
Value5.02.01.0711.0
Percentage of PaymentsToAcquireBusinessesGross100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired


Payments
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value3.00.00.0665.013230.01.0280.03.05.00.00.013120.0-57.050-469.0552652208.01946.0410.00.01.0281.0290.02.02.05.01.01.03.01.05.02.013
Percentage of PaymentsToAcquireBusinessesNetOfCashAcquired100.00.00.0100.0100.0100.00.0100.0100.00.0100.0100.00.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToDevelopSoftware

us-gaap:PaymentsToDevelopSoftware


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value131414161815169.017171316121323203215212224180.00.00.0
Percentage of PaymentsToDevelopSoftware100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:PensionAndOtherPostretirementBenefitsExpenseReversalOfExpenseNoncash

us-gaap:PensionAndOtherPostretirementBenefitsExpenseReversalOfExpenseNoncash


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-39000000.0-42000000.0-54000000.0-50000000.0-46000000.0-46000000.0-42000000.0-29000000.0-32000000.0-32000000.0-31000000.0-54000000.0-17000000.0-61000000.015000000.0-41000000.0-34000000.0-31000000.0
Percentage of PensionAndOtherPostretirementBenefitsExpenseReversalOfExpenseNoncash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromDivestitureOfBusinessesNetOfCashDivested

us-gaap:ProceedsFromDivestitureOfBusinessesNetOfCashDivested


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value0.06960.02100.04.0130.00.00.00.04.0570.00.00.0-1.0171513680.0135.0200.00.00.0
Percentage of ProceedsFromDivestitureOfBusinessesNetOfCashDivested0.0100.00.0100.00.0100.0100.00.00.00.00.0100.0100.00.00.00.0100.0100.0100.0100.0100.00.0100.0100.0100.00.00.00.0

us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromIssuanceOfCommonStock


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.01.08.03.02.03.0144.05.022243.07.011177.037201916171129114935281350435043431912181211144.0231910.09.06.011
Percentage of ProceedsFromIssuanceOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromIssuanceOfSeniorLongTermDebt

us-gaap:ProceedsFromIssuanceOfSeniorLongTermDebt


Proceeds
Period End2020-12-312020-09-302019-12-312019-09-302018-12-312018-09-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value0.00.00.09970.0998-1.00.06500.00.00.06099970.00.00.00.00.0
Percentage of ProceedsFromIssuanceOfSeniorLongTermDebt0.00.00.0100.00.0100.0100.00.0100.00.00.00.0100.0100.00.00.00.00.00.0

us-gaap:ProceedsFromPaymentsToMinorityShareholders

us-gaap:ProceedsFromPaymentsToMinorityShareholders


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
Value-4000000.0-17000000.0-1000000.0-13000000.0-13000000.0-1000000.0-33000000.0-1000000.0-21000000.00-6000000.0-2000000.0-18000000.00-32000000.0-5000000.0-14000000.0-1000000.0-4000000.0-2000000.0-11000000.0-4000000.0-2000000.0-11000000.0-5000000.0-3000000.0
Percentage of ProceedsFromPaymentsToMinorityShareholders100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProvisionForDoubtfulAccounts

us-gaap:ProvisionForDoubtfulAccounts


Provision
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value0.08.01.00.04.024-3.02.02.08.0-2.00.03.07.02.04.02.09.0114.08.0132.02.01.00.01.01.01.01.00.01.01.01.07.03.02.04.02.01.00.01.0
Percentage of ProvisionForDoubtfulAccounts0.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0

us-gaap:ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent us-gaap:StatementEquityComponents

us-gaap:ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value-14.0-39.0-9.0-9.0-3.0-11.0-6.0-2.0-4.0-2.0-23.0-9.0-3.0-7.0-12.0-10.0-8.0-10.0-12.0-9.0-15.0
Percentage of ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedOtherComprehensiveIncome


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value-11.0-82.0-10.0-13.0-5.0-12.0-8.0-4.0-4.0-7.0-26.0-14.0-9.0-17.0-11.0-21.0-23.0-29.0-3.0-10.0
Percentage of ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent78.6210.3111.1144.4166.7109.1133.3200.0100.0350.0113.0155.6300.0242.991.7210.0287.5290.033.366.7

us-gaap:AccumulatedTranslationAdjustment


Reclassification
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.0-44.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent-0.0112.8-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value3.01.0-1.0-4.0-2.0-1.0-2.0-2.00.0-5.0
Percentage of ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent-21.4-2.611.144.466.79.133.3100.0-0.0250.0

us-gaap:ReclassificationFromAociCurrentPeriodTax

us-gaap:ReclassificationFromAociCurrentPeriodTax


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value-1.06.0-2.0-2.0-7.00.00.02.03.01.0-4.09.0111.01.04.0-7.0-3.02.01.0-1.03.00.01.02.0
Percentage of ReclassificationFromAociCurrentPeriodTax100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:ShortTermLeaseCost

us-gaap:ShortTermLeaseCost


Short
Period End2021-06-302020-12-312020-09-302019-12-312019-09-30
Value1000000.001000000.01000000.01000000.0
Percentage of ShortTermLeaseCost100.00.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesShareBasedCompensation us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesShareBasedCompensation

us-gaap:CommonStock


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value0.0140.0090.1080.0370.0360.0560.0520.2890.0730.0810.2770.30.2010.1810.37313410.3080.2920.27318090.1550.5360.444
Percentage of StockIssuedDuringPeriodSharesShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1.01.03.02.03.04.05.0223.07.011186.018202210.02410.028125137
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation us-gaap:StatementEquityComponents

us-gaap:CommonStockIncludingAdditionalPaidInCapital


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1.01.03.02.03.04.05.0223.07.011186.018202210.02410.028125137
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Parent


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1.01.03.02.03.04.05.0223.07.011186.018202210.02410.028125137
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SubleaseIncome

us-gaap:SubleaseIncome


Sublease
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value5.05.05.06.05.05.05.03.04.04.0
Percentage of SubleaseIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:VariableLeaseCost

us-gaap:VariableLeaseCost


Variable
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value131316141310.08.0131713
Percentage of VariableLeaseCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:AdjustmentsToAdditionalPaidInCapitalForeignCurrencyTranslationGainLoss

wltw:AdjustmentsToAdditionalPaidInCapitalForeignCurrencyTranslationGainLoss


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value-1000000.04000000.0-5000000.0-1000000.04000000.05000000.0-1000000.0-3000000.010000000.0-4000000.0-1000000.0-6000000.0-2000000.0
Percentage of AdjustmentsToAdditionalPaidInCapitalForeignCurrencyTranslationGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:AdjustmentsToAdditionalPaidInCapitalForeignCurrencyTranslationGainLoss us-gaap:StatementEquityComponents

us-gaap:CommonStockIncludingAdditionalPaidInCapital


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value-1000000.04000000.0-5000000.0-1000000.04000000.05000000.0-1000000.0-3000000.010000000.0-4000000.0-1000000.0-6000000.0-2000000.0
Percentage of AdjustmentsToAdditionalPaidInCapitalForeignCurrencyTranslationGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Parent


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value-1000000.04000000.0-5000000.0-1000000.04000000.05000000.0-1000000.0-3000000.010000000.0-4000000.0-1000000.0-6000000.0-2000000.0
Percentage of AdjustmentsToAdditionalPaidInCapitalForeignCurrencyTranslationGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndNetSettlements

wltw:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndNetSettlements


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value20126.0129.01410.0-7.0111.03.0
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndNetSettlements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndNetSettlements us-gaap:StatementEquityComponents

us-gaap:CommonStockIncludingAdditionalPaidInCapital


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value20126.0129.01410.0-7.0111.03.0
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndNetSettlements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Parent


Adjustments
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value20126.0129.01410.0-7.0111.03.0
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndNetSettlements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:BusinessCombinationIntegrationRelatedCostsCredits

wltw:BusinessCombinationIntegrationRelatedCostsCredits


Business
Period 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
Value51244542149.01.06.00.06.05450
Percentage of BusinessCombinationIntegrationRelatedCostsCredits100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0

wltw:BusinessCombinationIntegrationRelatedTransactionCosts us-gaap:ConsolidationItems

wltw:BusinessCombinationIntegrationRelatedTransactionCosts

us-gaap:MaterialReconcilingItems


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value51244542149.01.06.00.06.05450554392746340
Percentage of BusinessCombinationIntegrationRelatedTransactionCosts100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:DefinedBenefitPlansPercentageOfObligationFromPlans

wltw:DefinedBenefitPlansPercentageOfObligationFromPlans


Defined
Period End2021-06-302021-03-312020-12-31
Value099.00
Percentage of DefinedBenefitPlansPercentageOfObligationFromPlans0.0100.00.0

wltw:DepreciationNotIncludingIntegrationComponent

wltw:DepreciationNotIncludingIntegrationComponent


Depreciation
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value7271679869585954555351493454515246454443
Percentage of DepreciationNotIncludingIntegrationComponent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:DerivativeInstrumentsDesignatedAsHedgingInstrumentsGainLossNet us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

wltw:DerivativeInstrumentsDesignatedAsHedgingInstrumentsGainLossNet

wltw:MaxMatthiessen


Derivative
Period End2020-09-30
Value-1000000.0
Percentage of DerivativeInstrumentsDesignatedAsHedgingInstrumentsGainLossNet100.0

wltw:DilutiveSecuritiesEffectOnBasicEarningsPerShare

wltw:DilutiveSecuritiesEffectOnBasicEarningsPerShare


Dilutive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-0.01-0.01-0.01-0.01-0.01-0.02-0.0100-0.01-0.01-0.010-0.01-0.010
Percentage of DilutiveSecuritiesEffectOnBasicEarningsPerShare100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.00.0100.0100.00.0

wltw:FiniteLivedIntangibleAssetsDisposed

wltw:FiniteLivedIntangibleAssetsDisposed


Finite
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.0541.0641.03.05.01.00.0
Percentage of FiniteLivedIntangibleAssetsDisposed0.0100.0100.0100.0100.0100.0100.0100.00.0

wltw:FiniteLivedIntangibleAssetsDisposed us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships


Finite
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.0460.0171.02.05.01.00.0
Percentage of FiniteLivedIntangibleAssetsDisposed0.085.20.026.6100.066.7100.0100.00.0

us-gaap:OtherIntangibleAssets


Finite
Period End2020-12-312020-09-302018-12-31
Value1.0470.0
Percentage of FiniteLivedIntangibleAssetsDisposed100.073.40.0

us-gaap:TrademarksAndTradeNames


Finite
Period End2021-06-302021-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.08.00.00.00.00.00.0
Percentage of FiniteLivedIntangibleAssetsDisposed0.014.80.00.00.00.00.0

wltw:IncreaseDecreaseInFiduciaryAssets

wltw:IncreaseDecreaseInFiduciaryAssets


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-586.01784-679.0-747.03272873-977.0-619.0-529.02490-459.0-895.08671326-66.0
Percentage of IncreaseDecreaseInFiduciaryAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:IncreaseDecreaseInFiduciaryLiabilities

wltw:IncreaseDecreaseInFiduciaryLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-586.01784-679.0-747.03272873-977.0-619.0-529.02490-459.0-895.08671326-66.0
Percentage of IncreaseDecreaseInFiduciaryLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:IncreaseDecreaseInProvisionForLiabilities

wltw:IncreaseDecreaseInProvisionForLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value8.0-7.0-161.020-10.013-25.0118.010.0-41.0
Percentage of IncreaseDecreaseInProvisionForLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:IndividualRevenueStreamsPercentageOfTotalRevenue us-gaap:ProductOrService, us-gaap:Range

wltw:IndividualRevenueStreamsPercentageOfTotalRevenue

us-gaap:ProductAndServiceOther, srt:Maximum


Individual
Period End2021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value5.00.050.0500.060.050.0500.06
Percentage of IndividualRevenueStreamsPercentageOfTotalRevenue100.0100.0100.00.0100.0100.0100.00.0100.0

wltw:MiscellaneousOtherNonOperatingIncomeExpense

wltw:MiscellaneousOtherNonOperatingIncomeExpense


Miscellaneous
Period End2020-09-302020-06-302020-03-31
Value-2000000.002000000.0
Percentage of MiscellaneousOtherNonOperatingIncomeExpense100.00.0100.0

wltw:NoncontrollingInterestDecreaseFromSale

wltw:NoncontrollingInterestDecreaseFromSale


Noncontrolling
Period End2021-06-302021-03-312020-06-30
Value1.0521.0
Percentage of NoncontrollingInterestDecreaseFromSale100.0100.0100.0

wltw:NoncontrollingInterestDecreaseFromSale us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Noncontrolling
Period End2021-06-302021-03-312020-06-30
Value1.0521.0
Percentage of NoncontrollingInterestDecreaseFromSale100.0100.0100.0

wltw:OperatingLeaseRightOfUseAssetAmortization

wltw:OperatingLeaseRightOfUseAssetAmortization


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value36373636403441353636
Percentage of OperatingLeaseRightOfUseAssetAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OtherComprehensiveIncomeLossNetOfTaxIncludingPortionAttributableToNonredeemableNoncontrollingInterest

wltw:OtherComprehensiveIncomeLossNetOfTaxIncludingPortionAttributableToNonredeemableNoncontrollingInterest


Other
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value5013856-220.0-122.0-17.022-22.0-175.08492138-23.0
Percentage of OtherComprehensiveIncomeLossNetOfTaxIncludingPortionAttributableToNonredeemableNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OtherComprehensiveIncomeLossNetOfTaxIncludingPortionAttributableToNonredeemableNoncontrollingInterest us-gaap:StatementEquityComponents

us-gaap:AociIncludingPortionAttributableToNoncontrollingInterest


Other
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value4813756-219.0-120.0-19.023-22.0-175.083100132-24.0
Percentage of OtherComprehensiveIncomeLossNetOfTaxIncludingPortionAttributableToNonredeemableNoncontrollingInterest96.099.3100.099.598.4111.8104.5100.0100.098.8108.795.7104.3

us-gaap:NoncontrollingInterest


Other
Period End2021-03-312020-09-302020-03-312019-09-302019-06-302019-03-312018-03-312017-09-302017-06-302017-03-31
Value2.01.0-1.0-2.02.0-1.01.0-8.06.01.0
Percentage of OtherComprehensiveIncomeLossNetOfTaxIncludingPortionAttributableToNonredeemableNoncontrollingInterest4.00.70.51.6-11.8-4.51.2-8.74.3-4.3

us-gaap:Parent


Other
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value4813756-219.0-120.0-19.023-22.0-175.083100132-24.0
Percentage of OtherComprehensiveIncomeLossNetOfTaxIncludingPortionAttributableToNonredeemableNoncontrollingInterest96.099.3100.099.598.4111.8104.5100.0100.098.8108.795.7104.3

wltw:PaymentsForDeferredContingentConsiderationFinancingActivities

wltw:PaymentsForDeferredContingentConsiderationFinancingActivities


Payments
Period End2021-06-302021-03-312019-12-312019-09-302018-12-312018-09-302017-12-312017-09-302017-06-302016-12-312016-09-30
Value0.01710.00.00.09.022-1.0443.064
Percentage of PaymentsForDeferredContingentConsiderationFinancingActivities0.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0

wltw:PaymentsToAcquireFixedAssetsAndSoftwareForInternalUse

wltw:PaymentsToAcquireFixedAssetsAndSoftwareForInternalUse


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value4237404869667155635759
Percentage of PaymentsToAcquireFixedAssetsAndSoftwareForInternalUse100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:ReimbursableExpensesAndOther

wltw:ReimbursableExpensesAndOther


Reimbursable
Period End2021-06-302021-03-312020-06-302020-03-31
Value169.01927
Percentage of ReimbursableExpensesAndOther100.0100.0100.0100.0

wltw:ReimbursableExpensesAndOther us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Reimbursable
Period End2021-06-302021-03-312020-06-302020-03-31
Value-1.0-5.04.06.0
Percentage of ReimbursableExpensesAndOther-6.2-55.621.122.2

wltw:ReimbursableExpensesAndOther us-gaap:StatementBusinessSegments

wltw:BenefitsDeliveryAndAdministration


Reimbursable
Period End2021-06-302021-03-312020-06-302020-03-31
Value2.02.02.03.0
Percentage of ReimbursableExpensesAndOther12.522.210.511.1

wltw:HumanCapitalAndBenefits


Reimbursable
Period End2021-06-302021-03-312020-06-302020-03-31
Value12111115
Percentage of ReimbursableExpensesAndOther75.0122.257.955.6

wltw:InvestmentRiskAndReinsurance


Reimbursable
Period End2021-06-302021-03-312020-06-302020-03-31
Value2.01.01.03.0
Percentage of ReimbursableExpensesAndOther12.511.15.311.1

dei:EntityNumberOfEmployees

dei:EntityNumberOfEmployees


Entity
Period End2021-06-302021-03-312020-12-312020-09-302015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value46000.046000.046000.045000.019300.018200.017951.017470.017155.017101.017133.0
Percentage of EntityNumberOfEmployees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccountsPayableOtherCurrent

us-gaap:AccountsPayableOtherCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value961913862832854856737793688691679715670772
Percentage of AccountsPayableOtherCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccountsReceivableNetNoncurrent

us-gaap:AccountsReceivableNetNoncurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value1922343833273020171720232233332726282830232929293327242825
Percentage of AccountsReceivableNetNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccruedSalesCommissionCurrent

us-gaap:AccruedSalesCommissionCurrent


Accrued
Period End2021-06-302020-12-312019-12-312019-09-302018-12-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value191173179186169172186184204187180177
Percentage of AccruedSalesCommissionCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AllowanceForDoubtfulAccountsReceivable

us-gaap:AllowanceForDoubtfulAccountsReceivable


Allowance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-01
Value444441435755374043444049494845
Percentage of AllowanceForDoubtfulAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AlternativeInvestmentMeasurementInput us-gaap:FairValueByLiabilityClass, us-gaap:MeasurementInputType

us-gaap:AlternativeInvestmentMeasurementInput

us-gaap:Obligations, us-gaap:MeasurementInputDiscountRate


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value10.8610.929.469.129.039.80.101612.213.09.99.929.889.64
Percentage of AlternativeInvestmentMeasurementInput100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AlternativeInvestmentMeasurementInput us-gaap:Range, us-gaap:FairValueByLiabilityClass, us-gaap:MeasurementInputType

srt:Minimum, us-gaap:Obligations, us-gaap:MeasurementInputDiscountRate


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value3.533.533.533.533.536.98
Percentage of AlternativeInvestmentMeasurementInput32.532.337.338.739.171.2

us-gaap:AssetsNet us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:AssetsNet

wltw:Miller


Assets
Period End2020-12-31
Value350
Percentage of AssetsNet100.0

us-gaap:BilledContractReceivables

us-gaap:BilledContractReceivables


Billed
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-01
Value172817271697155017441870183116381865184717021614182720591933
Percentage of BilledContractReceivables100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CapitalLeaseObligations us-gaap:LossContingenciesByNatureOfContingency

us-gaap:CapitalLeaseObligations

us-gaap:PropertyLeaseGuarantee


Capital
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value5.06.07.08.09.010.0
Percentage of CapitalLeaseObligations100.0100.0100.0100.0100.0100.0

us-gaap:CapitalizedContractCostNet

us-gaap:CapitalizedContractCostNet


Capitalized
Period End2020-12-312019-12-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value206177148119118109126
Percentage of CapitalizedContractCostNet100.0100.0100.0100.0100.0100.0100.0

us-gaap:CapitalizedContractCostNetCurrent

us-gaap:CapitalizedContractCostNetCurrent


Capitalized
Period End2021-03-312020-12-312019-12-31
Value74108101
Percentage of CapitalizedContractCostNetCurrent100.0100.0100.0

us-gaap:CapitalizedContractCostNetNoncurrent

us-gaap:CapitalizedContractCostNetNoncurrent


Capitalized
Period End2020-12-312019-12-31
Value9876
Percentage of CapitalizedContractCostNetNoncurrent100.0100.0

us-gaap:ContractWithCustomerAssetNetCurrent

us-gaap:ContractWithCustomerAssetNetCurrent


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-01
Value278334413189234282356146198247321132196196346
Percentage of ContractWithCustomerAssetNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerAssetNetNoncurrent

us-gaap:ContractWithCustomerAssetNetNoncurrent


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-01
Value405380329197172140105206.06.03.04.05.05.05.0
Percentage of ContractWithCustomerAssetNetNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiability

us-gaap:ContractWithCustomerLiability


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-01-01
Value638620549602558562538481512483448463
Percentage of ContractWithCustomerLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrumentAnnualPrincipalPayment us-gaap:DebtInstrument

us-gaap:DebtInstrumentAnnualPrincipalPayment

wltw:SeniorNotesDue202105750


Debt
Period End2021-03-31
Value500
Percentage of DebtInstrumentAnnualPrincipalPayment100.0

us-gaap:DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible

us-gaap:DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible


Decrease
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value3.03.02.03.04.00.0
Percentage of DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible100.0100.0100.0100.0100.00.0

us-gaap:DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible us-gaap:Range

srt:Maximum


Decrease
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-30
Value8.08.08.08.07.03.03.03.04.0
Percentage of DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible0.00.00.00.00.00.00.00.00.0

srt:Minimum


Decrease
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-30
Value3.04.04.03.03.01.01.01.02.0
Percentage of DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible0.00.00.00.00.00.00.00.00.0

us-gaap:DeferredCompensationLiabilityClassifiedNoncurrent

us-gaap:DeferredCompensationLiabilityClassifiedNoncurrent


Deferred
Period End2021-06-302020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value118117150139137132125138137135127124111104100102102109113909288928889809799101109119111106111122120
Percentage of DeferredCompensationLiabilityClassifiedNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredCompensationLiabilityCurrent

us-gaap:DeferredCompensationLiabilityCurrent


Deferred
Period End2021-06-302020-12-312019-12-312018-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-312013-09-302012-12-31
Value40571414121312171712262412
Percentage of DeferredCompensationLiabilityCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredCompensationPlanAssets

us-gaap:DeferredCompensationPlanAssets


Deferred
Period End2020-12-312020-09-302019-12-312019-09-302019-06-302018-12-312018-09-302017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value1171191501401371251381351111041001021021091139092889288888097969710511410789111115114
Percentage of DeferredCompensationPlanAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredIncomeTaxAssetsNet


Deferred
Period End2020-12-312020-09-302019-12-31
Value958172
Percentage of DeferredIncomeTaxAssetsNet100.0100.0100.0

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredIncomeTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value13411339110711611708463274
Percentage of DeferredIncomeTaxLiabilities100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxLiabilities us-gaap:BalanceSheetLocation

wltw:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-31
Value561526
Percentage of DeferredIncomeTaxLiabilities41.839.3

us-gaap:DeferredTaxAssetsCapitalLossCarryforwards

us-gaap:DeferredTaxAssetsCapitalLossCarryforwards


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value403330282833
Percentage of DeferredTaxAssetsCapitalLossCarryforwards100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsDerivativeInstruments

us-gaap:DeferredTaxAssetsDerivativeInstruments


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value1.00.01.018124.0
Percentage of DeferredTaxAssetsDerivativeInstruments100.00.0100.0100.0100.0100.0

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
Value9599616887541028486426383451432294
Percentage of DeferredTaxAssetsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value9211691145116115
Percentage of DeferredTaxAssetsOperatingLossCarryforwards100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards us-gaap:IncomeTaxAuthority

wltw:FederalAndForeignTaxAuthority


Deferred
Period End2020-12-312019-12-312018-12-31
Value258379288
Percentage of DeferredTaxAssetsOperatingLossCarryforwards280.4326.7316.5

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards us-gaap:StatementGeographical, us-gaap:IncomeTaxAuthority

country:US, us-gaap:StateAndLocalJurisdiction


Deferred
Period End2020-12-312019-12-31
Value621631
Percentage of DeferredTaxAssetsOperatingLossCarryforwards675.0544.0

us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration us-gaap:IncomeTaxAuthority

us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration

wltw:FederalAndForeignTaxAuthority


Deferred
Period End2020-12-312019-12-31
Value209277
Percentage of DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration100.0100.0

us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration us-gaap:StatementGeographical, us-gaap:IncomeTaxAuthority

country:US, us-gaap:StateAndLocalJurisdiction


Deferred
Period End2020-12-312019-12-31
Value9743
Percentage of DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration46.415.5

us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration us-gaap:IncomeTaxAuthority, us-gaap:TaxPeriod

us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration

wltw:FederalAndForeignTaxAuthority, wltw:TaxYear2021Through2040


Deferred
Period End2020-12-31
Value49
Percentage of DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration100.0

us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration us-gaap:StatementGeographical, us-gaap:IncomeTaxAuthority, us-gaap:TaxPeriod

country:US, us-gaap:StateAndLocalJurisdiction, wltw:TaxYear2021Through2040


Deferred
Period End2020-12-31
Value524
Percentage of DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration1069.4

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits


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
Value9086826983343437484546
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits


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
Value3343262853394671091094710110562
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value251822243616222540
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesDerivatives

us-gaap:DeferredTaxLiabilitiesDerivatives


Deferred
Period End2020-12-312019-12-312018-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value1000000.03000000.0003000000.02000000.04000000.06000000.0
Percentage of DeferredTaxLiabilitiesDerivatives100.0100.00.00.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets


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
Value7888658259291431289149120118149155
Percentage of DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesPrepaidExpenses

us-gaap:DeferredTaxLiabilitiesPrepaidExpenses


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value15212110111485111625635
Percentage of DeferredTaxLiabilitiesPrepaidExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value7853375673323844514225
Percentage of DeferredTaxLiabilitiesPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesTaxDeferredIncome

us-gaap:DeferredTaxLiabilitiesTaxDeferredIncome


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
Value1631201446211931252329267.0
Percentage of DeferredTaxLiabilitiesTaxDeferredIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value48414259366641653899
Percentage of DefinedBenefitPlanAccumulatedBenefitObligation100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value52914768418744764169
Percentage of DefinedBenefitPlanAccumulatedBenefitObligation109.3112.0114.2107.5106.9

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value918810698790696
Percentage of DefinedBenefitPlanAccumulatedBenefitObligation19.019.019.019.017.9

us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value919087123
Percentage of DefinedBenefitPlanAccumulatedBenefitObligation1.92.12.43.0

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax

country:GB, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-31
Value12671072
Percentage of DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-31
Value1143982
Percentage of DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax90.291.6

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-31
Value169128
Percentage of DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax13.311.9

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-31
Value1.0-7.0
Percentage of DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax0.1-0.7

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax

country:GB, us-gaap:PensionPlansDefinedBenefit