WLTW


Line plots across dimensions of each concept
Tables

Table of contents


us-gaap:StatementEquityComponents
us-gaap:SharesOutstanding
us-gaap:StatementClassOfStock
us-gaap:CommonStockSharesIssued
us-gaap:StatementClassOfStock
us-gaap:CommonStockSharesOutstanding

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:Revenues
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:ConsolidationItems
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:CostsAndExpenses
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:OperatingIncomeLoss
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:InterestExpense
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:OtherNonoperatingIncomeExpense
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:IncomeTaxExpenseBenefit
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:ProfitLoss
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:ComprehensiveIncomeNetOfTax
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest
us-gaap:ConsolidatedEntities

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:NetIncomeLoss
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest
us-gaap:ConsolidatedEntities

us-gaap:Assets
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:Liabilities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:LiabilitiesAndStockholdersEquity
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:StockholdersEquity
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:StatementEquityComponents

us-gaap:AssetsCurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:CashAndCashEquivalentsAtCarryingValue
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

us-gaap:AccountsReceivableNetCurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:OtherAssetsCurrent

us-gaap:PrepaidExpenseAndOtherAssetsCurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:NoncurrentAssets
us-gaap:StatementGeographical

us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:PropertyPlantAndEquipmentNet
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:PropertyPlantAndEquipmentByType
us-gaap:ConsolidatedEntities
us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:Goodwill
us-gaap:ConsolidatedEntities
us-gaap:StatementBusinessSegments

us-gaap:IntangibleAssetsNetExcludingGoodwill
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems

us-gaap:FiniteLivedIntangibleAssetsNet
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:OtherAssetsNoncurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:LiabilitiesCurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:LongTermDebtCurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:DebtInstrument
us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

us-gaap:TaxesPayableCurrent

us-gaap:OtherLiabilitiesCurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:DividendsPayableCurrent

us-gaap:LiabilitiesNoncurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:LongTermDebt
us-gaap:CreditFacility, us-gaap:DebtInstrument, dei:LegalEntity
us-gaap:CreditFacility, us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:DebtInstrument
us-gaap:DebtInstrument, dei:LegalEntity
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType
us-gaap:LongtermDebtType, dei:LegalEntity

us-gaap:LongTermDebtNoncurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:CreditFacility, us-gaap:DebtInstrument
us-gaap:DebtInstrument
us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

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

us-gaap:MinorityInterest
us-gaap:ConsolidatedEntities

us-gaap:OtherLiabilitiesNoncurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:StockholdersEquity
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:StatementEquityComponents

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:TreasuryStockValue

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:NetCashProvidedByUsedInOperatingActivities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:NetCashProvidedByUsedInInvestingActivities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:NetCashProvidedByUsedInFinancingActivities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:NetCashProvidedByUsedInOperatingActivities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:NetIncomeLoss
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:ProfitLoss
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:NetCashProvidedByUsedInInvestingActivities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:NetCashProvidedByUsedInFinancingActivities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:RepaymentsOfLongTermDebt
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:PaymentsForRepurchaseOfCommonStock
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

us-gaap:RepaymentsOfLongTermDebt
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:ShareBasedCompensation

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxAssetsNet

us-gaap:UnrecognizedTaxBenefits

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:OperatingLeaseRightOfUseAsset
us-gaap:ConsolidatedEntities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

us-gaap:AmortizationOfIntangibleAssets
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect
us-gaap:ConsolidatedEntities

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

us-gaap:Depreciation
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:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
us-gaap:ConsolidatedEntities

us-gaap:FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FinitelivedIntangibleAssetsAcquired1
us-gaap:BusinessAcquisition, us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax

us-gaap:GainLossOnSaleOfBusiness

us-gaap:GoodwillForeignCurrencyTranslationGainLoss
us-gaap:StatementBusinessSegments

us-gaap:GoodwillWrittenOffRelatedToSaleOfBusinessUnit
us-gaap:StatementBusinessSegments
us-gaap:ConsolidatedEntities
us-gaap:IncomeLossFromSubsidiariesNetOfTax
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:IncreaseDecreaseInAccountsReceivable

us-gaap:IncreaseDecreaseInOtherOperatingAssets

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities

us-gaap:InterestAndOtherIncome
us-gaap:StatementBusinessSegments

us-gaap:LaborAndRelatedExpense
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:OciBeforeReclassificationsNetOfTaxAttributableToParent
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation
us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax

us-gaap:OtherCostAndExpenseOperating
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

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

us-gaap:PaymentsForProceedsFromOtherInvestingActivities
us-gaap:ConsolidatedEntities

us-gaap:PaymentsOfDebtIssuanceCosts

us-gaap:PaymentsOfDividendsCommonStock
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

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

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:PaymentsToDevelopSoftware
us-gaap:ConsolidatedEntities

us-gaap:PensionAndOtherPostretirementBenefitsExpenseReversalOfExpenseNoncash

us-gaap:ProceedsFromDivestitureOfBusinessesNetOfCashDivested
us-gaap:ConsolidatedEntities

us-gaap:ProceedsFromIssuanceOfCommonStock
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

us-gaap:ProceedsFromIssuanceOfOtherLongTermDebt
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:ProceedsFromIssuanceOfSeniorLongTermDebt

us-gaap:ProceedsFromPaymentsToMinorityShareholders
us-gaap:ConsolidatedEntities

us-gaap:ProceedsFromRepaymentsOfLinesOfCredit
us-gaap:ConsolidationItems, dei:LegalEntity

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

us-gaap:ReclassificationFromAociCurrentPeriodTax

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
us-gaap:BusinessAcquisition
us-gaap:TypeOfArrangement

wltw:BusinessCombinationIntegrationRelatedCostsCredits
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:ConsolidationItems
wltw:BusinessCombinationIntegrationRelatedTransactionCosts
us-gaap:Range, us-gaap:DebtInstrument, us-gaap:VariableRate
wltw:DebtInstrumentAdditionalBasisSpreadOnVariableRate1

wltw:DepreciationNotIncludingIntegrationComponent
us-gaap:ConsolidatedEntities

wltw:DilutiveSecuritiesEffectOnBasicEarningsPerShare

wltw:FiniteLivedIntangibleAssetsDisposed
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

wltw:FiniteLivedIntangibleAssetsReclassificationOfFavorableLeaseAgreementAssetsToRightOfUseAssets
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

wltw:IncreaseDecreaseInFiduciaryAssets

wltw:IncreaseDecreaseInFiduciaryLiabilities

wltw:IncreaseDecreaseInProvisionForLiabilities
us-gaap:ProductOrService, us-gaap:Range
wltw:IndividualRevenueStreamsPercentageOfTotalRevenue
us-gaap:ConsolidatedEntities
wltw:IntercompanyIncomeExpense
us-gaap:ConsolidationItems, dei:LegalEntity

wltw:PaymentsForDeferredContingentConsiderationFinancingActivities
us-gaap:ConsolidatedEntities

wltw:PaymentsToAcquireFixedAssetsAndSoftwareForInternalUse
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
wltw:ProceedsFromRepaymentsOfIntercompanyInvestingActivities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:ConsolidatedEntities
wltw:RepaymentsOfIntercompanyFinancingActivities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:AccountsPayableOtherCurrent

us-gaap:AccountsReceivableNetNoncurrent

us-gaap:AccruedSalesCommissionCurrent
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
us-gaap:RetirementPlanType

us-gaap:AdditionalPaidInCapitalCommonStock

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

us-gaap:AssetsNoncurrent

us-gaap:BelowMarketLeaseAccumulatedAmortization
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:BelowMarketLeaseGross
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

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

us-gaap:CapitalizedContractCostNet

us-gaap:ContractWithCustomerAssetNetCurrent

us-gaap:ContractWithCustomerAssetNetNoncurrent

us-gaap:ContractWithCustomerLiability

us-gaap:DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible

us-gaap:DeferredCompensationLiabilityClassifiedNoncurrent

us-gaap:DeferredCompensationLiabilityCurrent

us-gaap:DeferredCompensationPlanAssets

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredIncomeTaxLiabilitiesNet
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems

us-gaap:DeferredTaxAssetsCapitalLossCarryforwards

us-gaap:DeferredTaxAssetsDerivativeInstruments

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsLiabilitiesNetNoncurrent

us-gaap:DeferredTaxAssetsNetNoncurrent

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:DeferredTaxLiabilitiesGrossNoncurrent

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:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesAfterTax
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditAfterTax
us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmountsRecognizedInBalanceSheet
us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent
us-gaap:ConsolidatedEntities
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:DefinedBenefitPlanBenefitObligation
us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
us-gaap:RetirementPlanSponsorLocation, 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:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanTaxStatus, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanFairValueOfPlanAssets
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType
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
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType, dei:LegalEntity
us-gaap:DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType, dei:LegalEntity
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:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency

us-gaap:DerivativeLiabilitiesCurrent
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation
us-gaap:DerivativeNotionalAmount
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:DueFromAffiliates
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:DueToAffiliateCurrentAndNoncurrent
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:AwardType
us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
us-gaap:Range, us-gaap:AwardType
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueLiabilitiesMeasuredOnRecurringBasisObligations
us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue

us-gaap:FinanceLeaseLiabilityNoncurrent

us-gaap:FinanceLeaseRightOfUseAsset

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsGross
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FundsHeldForClients
us-gaap:ConsolidatedEntities

us-gaap:GoodwillGross
us-gaap:StatementBusinessSegments

us-gaap:GoodwillImpairedAccumulatedImpairmentLoss

us-gaap:IncomeTaxesReceivable

us-gaap:InsuranceSettlementsReceivableNoncurrent

us-gaap:InterestPayableCurrent

us-gaap:LitigationReserveNoncurrent

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

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

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

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

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

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
us-gaap:CreditFacility, us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:DebtInstrument
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:MarketableSecurities
us-gaap:FairValueByMeasurementFrequency

us-gaap:OperatingLeaseLiability

us-gaap:OperatingLeaseLiabilityCurrent
us-gaap:ConsolidatedEntities

us-gaap:OperatingLeaseLiabilityNoncurrent
us-gaap:ConsolidatedEntities
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:RedeemableNoncontrollingInterestEquityCarryingAmount
us-gaap:ConsolidatedEntities

us-gaap:RestrictedCashCurrent
us-gaap:BalanceSheetLocation, us-gaap:DebtInstrument
us-gaap:RestructuringCostAndReserve, us-gaap:RestructuringPlan
us-gaap:RestructuringReserve
us-gaap:RestructuringPlan

us-gaap:RevenueRemainingPerformanceObligation
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
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:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:StatementClassOfStock
us-gaap:TreasuryStockShares

us-gaap:UnbilledReceivablesCurrent

us-gaap:UndistributedEarningsOfForeignSubsidiaries
us-gaap:NatureOfExpense

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

wltw:AccruedDiscretionaryAndIncentiveCompensation

wltw:AccruedExpensesNotCurrentlyDeductible

wltw:AssetsNoncurrentBeforeInvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

wltw:BusinessCombinationContingentConsiderationLiabilityAndDeferredConsiderationCurrent

wltw:BusinessCombinationContingentConsiderationLiabilityAndDeferredConsiderationNoncurrent

wltw:DeferredCompensationPlanAssetsCurrent

wltw:DeferredContractCostsCurrent

wltw:DeferredContractCostsNoncurrent

wltw:DeferredRevenueAndAccruedLiabilitiesCurrent
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity

wltw:DeferredTaxAssetsOperatingLeaseLiabilities

wltw:DeferredTaxLiabilitiesOperatingLeaseRightOfUseAssets

wltw:DefinedBenefitPlanDividendAndInterestReceivable

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
us-gaap:RetirementPlanType

wltw:DefinedBenefitPlanNetAssetsHeldInInvestments

wltw:DefinedBenefitPlanNetPayableReceivableForInvestmentsPurchased

wltw:DefinedBenefitPlanOtherAdjustments

wltw:DefinedBenefitPlanPostretirementHealthAssets

wltw:DerivativesAndInvestmentsCurrent

wltw:FiduciaryLiabilitiesCurrent
us-gaap:ConsolidatedEntities

wltw:FinanceLeaseRightOfUseAssetAccumulatedDepreciation

wltw:FinanceLeaseRightOfUseAssetGross

wltw:PayrollRelatedLiabilitiesCurrent

wltw:PrepaidBonusesCurrent

wltw:PrepaidExpenseAndAccruedRevenueReceivableCurrent

wltw:PrepaidExpenseAndAccruedRevenueReceivableNoncurrent

wltw:ProvisionForLiabilitiesNonCurrent
us-gaap:ConsolidatedEntities

wltw:UnrecognizedTaxBenefitsIncludingInterest

Tables

  2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
 us-gaap:SharesOutstanding us-gaap:StatementEquityComponents us-gaap:CommonStock▁▁▁▁▁▁▁▁▁▁▁▁█▁▁▁▁▁▁▁▁1281281281291281291301321321321341351362971371381386867676767NANANA67520NANANANANANANANANANANANANANANANANANA
 us-gaap:CommonStockSharesIssued us-gaap:StatementClassOfStock wltw:OrdinaryShareOne▁▁▁▂▁▂▃▄▄▄▆▆█128128128129128129130132132132134135137NANANA68NANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CommonStockSharesOutstanding us-gaap:StatementClassOfStock wltw:OrdinaryShareOne▁▁▁▂▁▂▃▄▄▄▆▇█128128128129128129130132132132134135136NANANA68NANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:EarningsPerShareBasic █▂▃▅▆▂▂▄▄▁▂▅▃▁▂▄▁▃▂▃▂▂▂▄4.20.581.062.212.910.340.441.621.85-0.40.242.511.04-0.230.521.76-0.350.650.391.170.4299999999999997-0.040.261.37NA-0.150.61.27NA0.150.621.290.13999999999999990.350.490.20.58000000000000010.38NA1.21NANANA
us-gaap:EarningsPerShareDiluted █▂▃▅▆▂▂▄▄▁▂▅▃▁▂▄▁▃▂▃▂▂▂▄4.180.581.062.22.890.330.441.611.84-0.40.242.51.03-0.230.511.75-0.350.640.381.150.42999999999999994-0.040.261.35NA-0.150.591.24NA0.150.611.280.13999999999999990.340.480.20.57000000000000030.37NA1.2NANANA
  2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:Revenues █▆▆▇▇▅▆▇▆▅▅▇▅▅▅▆▂▁▂▂▂▁▂▂▂▁▂▂▂▁▁▂▁▁▁▂▁▁▁▂▁▁▁269019892048231223721859199022922078185219532319192717771949223497484692210879588129351097919795890105187175484210138197628611008833733799972824725784
 us-gaap:Revenues us-gaap:ConsolidatedEntities srt:NonGuarantorSubsidiaries█▂▃▅▅▁▂▅▃▁2675197820452290235218511989228620731849NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ConsolidationItems us-gaap:OperatingSegments█▅▆▇▇▅▅▇▆▅▅▇▅▅▅▆▁▁▁▂26511962202222812329184419582268204718351926229619011761194822259748469221081NANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wltw:BenefitsDeliveryAndAdministration█▂▁▁▅▁▁▁▂▂595179126135390127119122194181NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wltw:CorporateRiskAndBroking█▂▃▄▆▂▃▅▆▁877651690728816622674740793600NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wltw:HumanCapitalAndBenefits█▅▄▆▇▃▃▆▃▁865807797829843778780832768733NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wltw:InvestmentRiskAndReinsurance▂▂▄█▁▂▃█▁▂314325409589280317385574288321NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:StatementBusinessSegments wltw:BenefitsDeliveryAndAdministration█▂▁▁▅▁▁▁600181128138392128121124NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:StatementBusinessSegments wltw:CorporateRiskAndBroking█▂▃▄▆▁▂▄878651690728816622674740NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:StatementBusinessSegments wltw:HumanCapitalAndBenefits█▃▃▅▆▁▁▅882822812843860792797846NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:StatementBusinessSegments wltw:InvestmentRiskAndReinsurance▂▂▄█▁▂▃█317327411591283319386576NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax █▅▆▇▇▅▅▇▆▅▅▇▅▅▅▆▂▁▂▂▂▁▂▂▂▁▂▂▂▁▁▂▁▁▁▂▁▁▁▂▁▁▁269019662030228623721826196622742078185219532319192717771949223497484692210879588129351097919795890105187175484210138197628611008833733799972824725784
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems us-gaap:OperatingSegments█▂▃▅▅▁▂▅26231944200922602306181619422255NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wltw:BenefitsDeliveryAndAdministration█▂▁▁▅▁▁▁595179126135390127119122NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wltw:CorporateRiskAndBroking█▂▃▄▇▁▃▅861637683719808606667734NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wltw:HumanCapitalAndBenefits█▄▃▅▆▁▁▆856804792823833773775828NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,wltw:InvestmentRiskAndReinsurance▂▂▄█▁▂▃█308320404579271306376567NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementGeographical us-gaap:OperatingSegments,srt:NorthAmerica█▂▂▂▅▁▁▁147410419999941226946955956NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementGeographical us-gaap:OperatingSegments,wltw:GreatBritain▄▁▅█▂▁▄█469402488560428389472572NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementGeographical us-gaap:OperatingSegments,wltw:International█▂▁▄▆▁▁▆277226219243264217219263NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementGeographical us-gaap:OperatingSegments,wltw:WesternEurope▆▁▂█▅▁▂█403275303463388264296464NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementGeographical,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,srt:NorthAmerica,wltw:BenefitsDeliveryAndAdministration█▂▁▁▅▁▁▁593179126135390127119122NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems,us-gaap:StatementGeographical,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,srt:NorthAmerica,wltw:CorporateRiskAndBroking█▅▅▁▆▄▄▁330288274220304266259215NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
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  2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
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  2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
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  2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
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 us-gaap:NetCashProvidedByUsedInInvestingActivities us-gaap:ConsolidationItems,dei:LegalEntity srt:ReportableLegalEntities,wltw:TrinityAcquisitionPlc█▅▁▄▆▄▄█284-111-561-137134-179-189326NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:NetCashProvidedByUsedInFinancingActivities ▁█▁▃▁▂▂▃▂▃▂▃▂▂▂▂▅▃▄▃▃▂▃▃-3771148-45682-361-207-311-24-233-50-19614-116-331-200-115547-10143-39-40-128-106-49NANANA18NA-104NA0-64-69-208127-67-89-120-17-28943NA
 us-gaap:NetCashProvidedByUsedInFinancingActivities us-gaap:ConsolidationItems srt:ConsolidationEliminations█▇▃▅▆▅▅▇▁1152758-800352221-171577-1684NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetCashProvidedByUsedInFinancingActivities us-gaap:ConsolidationItems,dei:LegalEntity srt:ReportableLegalEntities,wltw:WillisNorthAmericaInc▄█▃▃▁▃▃▃1101253-2119-562-576631NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RepaymentsOfLongTermDebt ▂▆▁▁▁▂▁▁▁▁▅▅▁▁▅█▁▂▁▁1708222101272221201969563640356451181715144NANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RepaymentsOfLongTermDebt us-gaap:ConsolidationItems,dei:LegalEntity srt:ReportableLegalEntities,wltw:TrinityAcquisitionPlc▆█▁▁▁▁▁▁171234000000NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PaymentsForRepurchaseOfCommonStock ▁█396NANA20113226907016629615617418438003641513838235NANANA0NA443719NANANANANANANANANANANA
 us-gaap:PaymentsForRepurchaseOfCommonStock us-gaap:ConsolidatedEntities,us-gaap:ConsolidationItems srt:ParentCompany,srt:ReportableLegalEntities▁█396NANA201132NANA70NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
us-gaap:RepaymentsOfLongTermDebt ▂▆▁▁▁▂▁▁▁▁▅▅▁▁▅█▁▂▁▁1708222101272221201969563640356451181715144NANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RepaymentsOfLongTermDebt us-gaap:ConsolidationItems,dei:LegalEntity srt:ReportableLegalEntities,wltw:TrinityAcquisitionPlc▆█▁▁▁▁▁▁171234000000NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA

Common Stock Value

Common Stock Par Or Stated Value Per Share

Shares Outstanding

us-gaap:StatementEquityComponents

us-gaap:SharesOutstanding

us-gaap:CommonStock



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value128128128129128129130132132132134135136297137138138686767676767520
Percentage of SharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Shares Issued

Common Stock Shares Issued

us-gaap:StatementClassOfStock

us-gaap:CommonStockSharesIssued

wltw:OrdinaryShareOne



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value12812812812912812913013213213213413513768
Percentage of CommonStockSharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Outstanding

us-gaap:StatementClassOfStock

us-gaap:CommonStockSharesOutstanding

wltw:OrdinaryShareOne



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value12812812812912812913013213213213413513668
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Authorized

Weighted Average Number Of Diluted Shares Outstanding

Weighted Average Number Of Shares Outstanding Basic

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-03-31
Value4.20.581.062.212.910.340.441.621.85-0.40.242.511.04-0.230.521.76-0.350.650.391.170.4299999999999997-0.040.261.37-0.150.61.270.150.621.290.13999999999999990.350.490.20.58000000000000010.381.21
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-03-31
Value4.180.581.062.22.890.330.441.611.84-0.40.242.51.03-0.230.511.75-0.350.640.381.150.42999999999999994-0.040.261.35-0.150.591.240.150.611.280.13999999999999990.340.480.20.57000000000000030.371.2
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Income Loss From Continuing Operations Per Basic Share

Income Loss From Continuing Operations Per Diluted Share

Revenues

us-gaap:Revenues



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value269019892048231223721859199022922078185219532319192717771949223497484692210879588129351097919795890105187175484210138197628611008833733799972824725784
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0101.2100.9101.1100.0101.8101.2100.8100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.00.00.00.00.01000000.00.00.00.00.0
Percentage of Revenues0.00.00.00.00.00.10.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.10.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value2675197820452290235218511989228620731849
Percentage of Revenues99.499.499.999.099.299.699.999.799.899.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax99.4100.6100.7100.299.2101.4101.2100.599.899.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

us-gaap:MaterialReconcilingItems



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value392726314315322435173126
Percentage of Revenues1.41.41.31.31.80.81.61.01.70.91.61.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.41.41.31.41.80.81.61.11.70.91.61.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems0.0122.7123.8119.20.0150.0133.3126.30.00.00.00.0

us-gaap:OperatingSegments



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value26511962202222812329184419582268204718351926229619011761194822259748469221081
Percentage of Revenues98.698.698.798.798.299.298.499.098.599.198.699.098.799.199.999.6100.0100.0100.099.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax98.699.899.699.898.2101.099.699.798.599.198.699.098.799.199.999.6100.0100.0100.099.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments0.0100.9100.6100.90.0101.5100.8100.60.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value151132220716
Percentage of Revenues0.60.60.11.00.80.40.10.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.60.11.00.80.40.10.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, wltw:BenefitsDeliveryAndAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value595179126135390127119122194181
Percentage of Revenues22.19.06.25.816.46.86.05.39.39.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.19.16.25.916.47.06.15.49.39.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:BenefitsDeliveryAndAdministration0.0100.0100.0100.00.0100.0100.0100.00.00.0

us-gaap:OperatingSegments, wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value877651690728816622674740793600
Percentage of Revenues32.632.733.731.534.433.533.932.338.232.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.633.134.031.834.434.134.332.538.232.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:CorporateRiskAndBroking0.0102.2101.0101.30.0102.6101.0100.80.00.0

us-gaap:OperatingSegments, wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value865807797829843778780832768733
Percentage of Revenues32.240.638.935.935.541.939.236.337.039.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.241.039.336.335.542.639.736.637.039.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:HumanCapitalAndBenefits0.0100.4100.6100.70.0100.6100.6100.50.00.0

us-gaap:OperatingSegments, wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value314325409589280317385574288321
Percentage of Revenues11.716.320.025.511.817.119.325.013.917.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.716.520.125.811.817.419.625.213.917.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:InvestmentRiskAndReinsurance0.0101.6101.2101.70.0103.6102.4101.20.00.0

us-gaap:StatementBusinessSegments

us-gaap:CorporateNonSegment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value13871221-2126
Percentage of Revenues0.50.40.30.50.9-0.10.60.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.40.30.50.9-0.10.60.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment0.0114.3116.7109.10.066.7133.3120.0

wltw:BenefitsDeliveryAndAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value600181128138392128121124
Percentage of Revenues22.39.16.26.016.56.96.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.39.26.36.016.57.06.25.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:BenefitsDeliveryAndAdministration0.0100.0100.0100.00.0100.0100.0100.0

wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value878651690728816622674740
Percentage of Revenues32.632.733.731.534.433.533.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.633.134.031.834.434.134.332.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:CorporateRiskAndBroking0.0102.2101.0101.30.0102.6101.0100.8

wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value882822812843860792797846
Percentage of Revenues32.841.339.636.536.342.640.136.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.841.840.036.936.343.440.537.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:HumanCapitalAndBenefits0.0100.4100.6100.70.0100.6100.6100.5

wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value317327411591283319386576
Percentage of Revenues11.816.420.125.611.917.219.425.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.816.620.225.911.917.519.625.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:InvestmentRiskAndReinsurance0.0101.6101.2101.70.0103.6102.4101.2

Revenue From Contract With Customer Excluding Assessed Tax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value269019662030228623721826196622742078185219532319192717771949223497484692210879588129351097919795890105187175484210138197628611008833733799972824725784
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value34444454
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.20.20.20.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.20.20.20.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MaterialReconcilingItems



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3622212641102419
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.31.11.01.11.70.51.20.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.31.11.01.11.70.51.20.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value26231944200922602306181619422255
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax97.598.999.098.997.299.598.899.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax97.598.999.098.997.299.598.899.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:MaterialReconcilingItems, us-gaap:CorporateNonSegment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1032719-741
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.40.20.10.30.8-0.40.20.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.40.20.10.30.8-0.40.20.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MaterialReconcilingItems, wltw:BenefitsDeliveryAndAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value52232122
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MaterialReconcilingItems, wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1715151417141714
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.80.70.60.70.80.90.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.80.70.60.70.80.90.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MaterialReconcilingItems, wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value32223212
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:CorporateNonSegment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value34444454
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.20.20.20.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.20.20.20.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:BenefitsDeliveryAndAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value595179126135390127119122
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.19.16.25.916.47.06.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.19.16.25.916.47.06.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value861637683719808606667734
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.032.433.631.534.133.233.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.032.433.631.534.133.233.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value856804792823833773775828
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax31.840.939.036.035.142.339.436.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax31.840.939.036.035.142.339.436.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value308320404579271306376567
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.416.319.925.311.416.819.124.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.416.319.925.311.416.819.124.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:StatementGeographical

us-gaap:CorporateNonSegment, srt:NorthAmerica



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value14443454
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.20.20.20.10.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.20.20.20.10.20.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment srt:NorthAmerica100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, srt:NorthAmerica



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value147410419999941226946955956
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax54.853.049.243.551.751.848.642.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax54.853.049.243.551.751.848.642.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:GreatBritain



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value469402488560428389472572
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.420.424.024.518.021.324.025.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.420.424.024.518.021.324.025.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:GreatBritain100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:International



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value277226219243264217219263
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.311.510.810.611.111.911.111.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.311.510.810.611.111.911.111.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:International100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, wltw:WesternEurope



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value403275303463388264296464
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax15.014.014.920.316.414.515.120.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax15.014.014.920.316.414.515.120.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:WesternEurope100.0100.0100.0100.0100.0100.0100.0100.0

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

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value593179126135390127119122
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.09.16.25.916.47.06.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.09.16.25.916.47.06.15.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value330288274220304266259215
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.314.613.59.612.814.613.29.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.314.613.59.612.814.613.29.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value470482478471454466467462
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.524.523.520.619.125.523.820.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.524.523.520.619.125.523.820.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value80881171647583105153
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.04.55.87.23.24.55.36.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.04.55.87.23.24.55.36.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments srt:NorthAmerica wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value203139172142193137170148
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.57.18.56.28.17.58.66.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.57.18.56.28.17.58.66.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:GreatBritain wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value121116120118119113120129
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.55.95.95.25.06.26.15.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.55.95.95.25.06.26.15.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:GreatBritain wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value145147196300116139182295
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.47.59.713.14.97.69.313.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.47.59.713.14.97.69.313.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:GreatBritain wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value139105109118136107117132
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.25.35.45.25.75.96.05.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.25.35.45.25.75.96.05.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:International wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value10183707997736483
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.84.23.43.54.14.03.33.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.84.23.43.54.14.03.33.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:International wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3438404631373848
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.31.92.02.01.32.01.92.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.31.92.02.01.32.01.92.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:International wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value18910512823917596121239
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.05.36.310.57.45.36.210.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.05.36.310.57.45.36.210.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:WesternEurope wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value164123124155163121124154
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.16.36.16.86.96.66.36.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.16.36.16.86.96.66.36.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:WesternEurope wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4947516949475171
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.82.42.53.02.12.62.63.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.82.42.53.02.12.62.63.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:WesternEurope wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductOrService

us-gaap:ProductAndServiceOther



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value13412511010711711389106
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.06.45.44.74.96.24.54.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.06.45.44.74.96.24.54.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Broking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1486877955114112097788991135
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax55.244.647.049.951.042.645.749.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax55.244.647.049.951.042.645.749.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value719676710728566718751795
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax26.734.435.031.823.939.338.235.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax26.734.435.031.823.939.338.235.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value284266234284414207247273
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.613.511.512.417.511.312.612.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.613.511.512.417.511.312.612.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:ProductAndServiceOther, us-gaap:CorporateNonSegment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value11110121
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.00.00.00.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.00.00.00.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther us-gaap:CorporateNonSegment100.0100.0100.0100.00.0100.0100.0100.0

us-gaap:ProductAndServiceOther, wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value21113123
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.00.00.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.00.00.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductAndServiceOther, wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value8079564771734043
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.04.02.82.13.04.02.01.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.04.02.82.13.04.02.01.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductAndServiceOther, wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value5144525843384559
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.92.22.62.51.82.12.32.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.92.22.62.51.82.12.32.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Broking, wltw:BenefitsDeliveryAndAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4475593260444
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.62.80.40.111.00.20.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.62.80.40.111.00.20.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Broking, wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value810589633660750554610664
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax30.130.031.228.931.630.331.029.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax30.130.031.228.931.630.331.029.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Broking, wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value8358647375546176
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.13.03.23.23.23.03.13.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.13.03.23.23.23.03.13.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Broking, wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value146175249405124166224391
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.48.912.317.75.29.111.417.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.48.912.317.75.29.111.417.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Broking wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting, us-gaap:CorporateNonSegment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value23334333
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.10.10.20.20.20.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.10.10.20.20.20.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting, wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3530363143373944
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.31.51.81.41.82.02.01.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.31.51.81.41.82.02.01.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting, wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value573545571580415576558577
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax21.327.728.125.417.531.528.425.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax21.327.728.125.417.531.528.425.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

wltw:Consulting, wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value10998100114104102107117
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.15.04.95.04.45.65.45.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.15.04.95.04.45.65.45.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:Consulting wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration, wltw:BenefitsDeliveryAndAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value148124117132130123115118
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.56.35.85.85.56.75.85.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.56.35.85.85.56.75.85.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration, wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1417132712141623
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.90.61.20.50.80.81.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.90.61.20.50.80.81.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration, wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value12012210112327270116132
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.56.25.05.411.53.85.95.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.56.25.05.411.53.85.95.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

wltw:OutsourcedAdministration, wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value233200
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.10.10.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.10.10.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:OutsourcedAdministration wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.00.00.0

us-gaap:StatementBusinessSegments

us-gaap:CorporateNonSegment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value13761123-395
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.40.30.51.0-0.20.50.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.40.30.51.0-0.20.50.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0

wltw:BenefitsDeliveryAndAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value600181128138392128121124
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.39.26.36.016.57.06.25.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax22.39.26.36.016.57.06.25.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:BenefitsDeliveryAndAdministration100.0100.0100.0100.0100.0100.0100.0100.0

wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value862637683719808606667734
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.032.433.631.534.133.233.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.032.433.631.534.133.233.932.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:CorporateRiskAndBroking100.0100.0100.0100.0100.0100.0100.0100.0

wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value873819807837850787792842
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.541.739.836.635.843.140.337.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.541.739.836.635.843.140.337.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:HumanCapitalAndBenefits100.0100.0100.0100.0100.0100.0100.0100.0

wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value311322406581274308377569
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.616.420.025.411.616.919.225.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.616.420.025.411.616.919.225.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax wltw:InvestmentRiskAndReinsurance100.0100.0100.0100.0100.0100.0100.0100.0

Sales Revenue Net

Operating Expenses

Costs And Expenses

us-gaap:CostsAndExpenses



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value20031882187219531902184219272033
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax74.595.792.285.480.2100.998.089.4

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302018-12-312018-09-30
Value30293937
Percentage of CostsAndExpenses1.51.52.12.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.11.51.62.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302018-12-312018-09-30
Value1951183118361784
Percentage of CostsAndExpenses97.497.396.596.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax72.593.177.497.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302018-12-312018-09-30
Value1002
Percentage of CostsAndExpenses0.00.00.00.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302018-12-312018-09-30
Value-1-1-1-2
Percentage of CostsAndExpenses-0.0-0.1-0.1-0.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.0-0.1-0.0-0.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302018-12-312018-09-30
Value0.00.01000000.00.0
Percentage of CostsAndExpenses0.00.00.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302018-12-312018-09-30
Value22232721
Percentage of CostsAndExpenses1.11.21.41.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.81.21.11.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.0

Operating Income Loss

us-gaap:OperatingIncomeLoss



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value687107176359470176325911041124463881136326227105293139341483267517128770179317819015623817710616930117382165
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax25.55.48.715.719.80.93.211.45.32.26.320.04.60.17.014.60.23.211.427.014.54.215.829.79.419.227.39.321.331.39.911.818.123.621.214.521.231.021.011.321.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-30-29-22-39-39-36-53-45-63-35
Percentage of OperatingIncomeLoss-4.4-27.1-12.5-10.9-8.3-211.8-84.1-17.4-57.3-85.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.1-1.5-1.1-1.7-1.6-2.0-2.7-2.0-3.0-1.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value7241472254005166715832417837
Percentage of OperatingIncomeLoss105.4137.4127.8111.4109.8394.1250.8125.1161.890.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax26.97.511.117.521.83.78.014.28.62.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-10-2-20-2-2-1-1-2
Percentage of OperatingIncomeLoss-0.10.0-1.1-0.60.0-11.8-3.2-0.4-0.9-4.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.00.0-0.1-0.10.0-0.1-0.1-0.0-0.0-0.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1110120003
Percentage of OperatingIncomeLoss0.10.90.60.00.211.80.00.00.07.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.00.00.00.10.00.00.00.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value866305357562738256304547435266354731389224363667197102178322
Percentage of OperatingIncomeLoss126.1285.0202.8156.5157.01505.9482.5211.2395.5648.8285.5157.9442.022400.0266.9204.69850.0377.8169.5109.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.215.517.624.631.114.015.524.120.914.418.131.520.212.618.629.920.212.119.329.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments33.015.717.824.932.014.115.724.30.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.00.00.00.0-1000000.00.00.00.0
Percentage of OperatingIncomeLoss0.00.00.00.0-0.20.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.0-0.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-7-12-260-7-14-40-19
Percentage of OperatingIncomeLoss-1.0-11.2-14.80.0-1.5-82.4-63.5-7.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.3-0.6-1.30.0-0.3-0.8-2.0-0.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, wltw:BenefitsDeliveryAndAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value311-21-25-21240-33-31-324436
Percentage of OperatingIncomeLoss45.3-19.6-14.2-5.851.1-194.1-49.2-12.440.087.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.6-1.1-1.2-0.910.1-1.8-1.6-1.42.11.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:BenefitsDeliveryAndAdministration52.3-11.7-19.8-15.661.5-26.0-26.1-26.20.00.0

us-gaap:OperatingSegments, wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value26681104127240669712521448
Percentage of OperatingIncomeLoss38.775.759.135.451.1388.2154.048.3194.5117.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.94.15.15.610.13.64.95.510.32.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:CorporateRiskAndBroking30.912.715.217.729.710.914.517.00.00.0

us-gaap:OperatingSegments, wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value261214169204253194149193164143
Percentage of OperatingIncomeLoss38.0200.096.056.853.81141.2236.574.5149.1348.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.710.98.38.910.710.67.68.57.97.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:HumanCapitalAndBenefits30.526.621.324.830.425.119.223.30.00.0

us-gaap:OperatingSegments, wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value283110925252989261-632
Percentage of OperatingIncomeLoss4.129.061.970.21.1170.6141.3100.8-5.578.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.01.65.411.00.21.64.511.5-0.31.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments wltw:InvestmentRiskAndReinsurance9.19.727.043.51.89.523.746.00.00.0

Interest Expense

us-gaap:InterestExpense



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value6262565454515251494746464645474639353533343435323032313233324438344042404143464743
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.33.22.82.42.32.82.62.22.42.52.42.02.42.52.42.14.04.13.83.03.54.23.72.93.83.62.94.23.93.25.45.03.94.05.05.55.14.45.66.55.5

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value2414136655
Percentage of InterestExpense3.26.51.87.41.95.911.511.810.210.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.20.00.20.00.20.30.30.20.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value8787878778
Percentage of InterestExpense12.911.314.313.014.813.715.413.714.317.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.40.40.30.30.40.40.30.30.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

us-gaap:MaterialReconcilingItems



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value626256545451-52514947-4646
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0-100.0100.0100.0100.0-100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.33.22.82.42.32.8-2.62.22.42.5-2.42.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems172.2281.8266.7207.7131.7510.0-216.7268.40.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2326242222282727
Percentage of InterestExpense37.141.942.940.740.754.951.952.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.91.31.21.00.91.51.41.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2925232123131111
Percentage of InterestExpense46.840.341.138.942.625.521.221.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.11.31.10.91.00.70.60.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value505567556170635618-29-30-20-1-146-1829923-618-9-307546
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.92.83.32.42.63.83.22.50.9-1.6-1.5-0.9-0.1-0.80.3-0.83.01.12.5-0.61.9-1.1-0.30.00.80.60.40.6

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value10000011-4848
Percentage of OtherNonoperatingIncomeExpense2.00.00.00.00.00.01.61.8-266.7-165.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.10.0-2.32.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value475467551353706255103187
Percentage of OtherNonoperatingIncomeExpense94.098.2100.0100.02218.0100.098.498.2572.2-644.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.72.73.32.457.03.83.22.45.010.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value00000000350
Percentage of OtherNonoperatingIncomeExpense0.00.00.00.00.00.00.00.0194.4-0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.01.70.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0000-1292000-41-197
Percentage of OtherNonoperatingIncomeExpense0.00.00.00.0-2118.00.00.00.0-227.8679.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.0-54.50.00.00.0-2.0-10.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.00.0

us-gaap:MaterialReconcilingItems



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value505567556170-63564938-3443
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0-100.0100.0272.2-131.0113.3-215.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.92.83.32.42.63.8-3.22.52.42.1-1.71.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MaterialReconcilingItems138.9250.0319.0211.5148.8700.0-262.5294.70.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value21000000
Percentage of OtherNonoperatingIncomeExpense4.01.80.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

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

Income Loss From Continuing Operations

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

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value675100187360477367426480-35
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax25.15.19.215.720.12.03.811.63.8-1.9

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value5145372770224548-22106
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest7.645.019.87.514.761.160.818.2-27.5-302.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.92.31.81.23.01.22.32.1-1.15.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value4461222173741662399625613598
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest66.1122.0116.0103.9348.4108.3129.797.0168.8-280.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.66.210.716.470.12.14.911.36.55.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-9-7-10-9-8-9-10-827-10
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest-1.3-7.0-5.3-2.5-1.7-25.0-13.5-3.033.828.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.3-0.4-0.5-0.4-0.3-0.5-0.5-0.41.3-0.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1110-1291200-41-194
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest0.11.00.50.0-270.65.60.00.0-51.2554.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.10.00.0-54.40.10.00.0-2.0-10.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1614218533
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest2.414.01.10.31.713.94.11.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.70.10.00.30.30.20.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value170-75-60-3336-23-60-35
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest25.2-75.0-32.1-9.27.5-63.9-81.1-13.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.3-3.8-3.0-1.41.5-1.3-3.1-1.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value12420386794-10943-17319846-107-2619184-11219563525963112948103668-223112810356732-2931
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.61.01.92.94.0-0.50.51.9-8.31.00.42.0-5.6-1.51.00.80.4-13.22.15.23.70.26.35.71.43.34.61.34.36.7-0.20.33.60.13.41.44.46.93.9-4.04.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-6312104-62588-7110
Percentage of IncomeTaxExpenseBenefit-50.860.026.36.0-66.0-50.088.918.641.052.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-2.30.60.50.2-2.60.30.40.4-3.40.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1752240691250939-14114
Percentage of IncomeTaxExpenseBenefit141.1110.0105.3103.0133.0-0.0100.090.781.573.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.51.12.03.05.30.00.51.7-6.80.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value000000002-1
Percentage of IncomeTaxExpenseBenefit0.00.00.00.00.0-0.00.00.0-1.2-5.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.1-0.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value42011101
Percentage of IncomeTaxExpenseBenefit3.210.00.01.51.1-10.00.02.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.00.00.00.10.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value8-16-12-730-16-8-5
Percentage of IncomeTaxExpenseBenefit6.5-80.0-31.6-10.431.9160.0-88.9-11.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.3-0.8-0.6-0.31.3-0.9-0.4-0.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Income Taxes Paid Net

Profit Loss

us-gaap:ProfitLoss



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value551801492933834665221253-5441352148-3176245-181167221483-84825074-27107223-80126110232296089421036591211868191
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.54.17.312.816.12.53.39.712.2-2.92.115.27.7-1.73.911.0-1.813.77.819.78.7-1.05.122.88.1-3.412.021.2-92.03.413.122.93.57.910.34.212.48.911.421.710.411.211.6

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value552841372933905063221250-35
Percentage of ProfitLoss100.2105.091.9100.0101.8108.796.9100.098.864.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.54.36.712.816.42.73.29.712.0-1.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value2711001773051537398721727684
Percentage of ProfitLoss49.2125.0118.8104.1401.384.8133.898.2109.1-155.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.15.18.713.364.82.14.49.513.34.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value544751382873784458215245-54
Percentage of ProfitLoss98.793.892.698.098.795.789.297.396.8100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.23.86.812.615.92.43.09.511.8-2.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1591-151-371-854-2434-54-51-539-829338
Percentage of ProfitLoss-288.7-188.8-249.0-291.5-635.5-117.4-78.5-243.9-327.7-625.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-59.1-7.7-18.3-37.4-102.6-3.0-2.6-23.7-39.918.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4581072221332-18-5144
Percentage of ProfitLoss83.112.548.375.486.7-39.1-7.765.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.00.53.59.714.0-1.0-0.36.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value317-38-441180-15-87-37
Percentage of ProfitLoss57.5-47.5-2.714.047.0-32.6-133.8-16.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.8-1.9-0.21.87.6-0.8-4.4-1.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value430-451193104422-11729840846165320-521-72-56222-10735150324-255-8272254451111835377256-180910666129102
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.0-2.35.913.61.91.2-6.013.119.62.58.413.8-27.0-4.1-2.99.9-11.04.116.329.8-26.6-10.17.723.25.712.517.47.09.125.3-22.01.212.36.515.513.9

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value442-351183176629-11130340062
Percentage of ComprehensiveIncomeNetOfTax102.877.899.2102.3150.0131.894.9101.798.0134.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.4-1.85.813.92.81.6-5.613.319.23.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value164-26164293124220-46331342261
Percentage of ComprehensiveIncomeNetOfTax38.157.8137.894.52822.790.939.3111.183.8567.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.1-1.38.112.852.41.1-2.314.616.514.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value430-451183114422-11729840846
Percentage of ComprehensiveIncomeNetOfTax100.0100.099.2100.3100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.0-2.35.813.61.91.2-6.013.119.62.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1133222-397-834-142010488-838-1198-110
Percentage of ComprehensiveIncomeNetOfTax-263.5-493.3-333.6-269.0-3227.345.5-417.1-281.2-293.6-239.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-42.111.3-19.6-36.5-59.90.524.8-36.9-57.7-5.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value350-87932047-41-178226
Percentage of ComprehensiveIncomeNetOfTax81.4193.378.265.815.9-186.4152.175.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.0-4.44.68.90.3-2.2-9.19.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value177-742319105-18-153-22
Percentage of ComprehensiveIncomeNetOfTax41.2164.419.36.1238.6-81.8130.8-7.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.6-3.81.10.84.4-1.0-7.8-1.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value83135526722-121611016-93-56-32-2141230183-24931
Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.20.60.20.20.10.30.31.1-0.60.80.50.00.10.3-0.40.3-0.60.7-0.30.2-0.20.10.40.10.20.30.00.10.80.4-0.30.50.90.40.1

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value83135526722-12
Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.20.60.20.20.10.30.31.1-0.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value438-421323154924-11130543034181331-525-73-62231-10430156321-253-8473258461131865378264-177911075132103
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.3-2.16.513.82.11.3-5.613.420.71.89.314.3-27.2-4.1-3.210.3-10.73.516.929.5-26.4-10.37.823.55.812.717.77.09.326.1-21.61.212.87.415.814.1

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value442-351183176629-11130340062
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.983.389.4100.6134.7120.8100.099.393.0182.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.4-1.85.813.92.81.6-5.613.319.23.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value172-23177298124722-40338364249
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest39.354.8134.194.62544.991.736.0110.884.7732.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.4-1.28.713.052.61.2-2.014.917.513.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value430-451183114422-11729840846
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest98.2107.189.498.789.891.7105.497.794.9135.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.0-2.35.813.61.91.2-6.013.119.62.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1133222-397-834-142010488-838-1198-110
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest-258.7-528.6-300.8-264.8-2898.041.7-439.6-274.8-278.6-323.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-42.111.3-19.6-36.5-59.90.524.8-36.9-57.7-5.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value350-87932047-41-178226
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest79.9207.170.564.814.3-170.8160.474.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.0-4.44.68.90.3-2.2-9.19.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value177-742319105-18-153-22
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest40.4176.217.46.0214.3-75.0137.8-7.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.6-3.81.10.84.4-1.0-7.8-1.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Net Income Loss

us-gaap:NetIncomeLoss



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value544751382873784458215245-5433344142-3272238-241177021076-74724668-27105219-8052610822525608534986489204797987
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.23.86.812.615.92.43.09.511.8-2.91.714.87.4-1.83.710.7-2.513.87.619.37.9-0.95.022.47.4-3.411.820.8-92.43.412.822.23.17.99.93.411.88.711.121.09.610.911.1

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value552841372933905063221250-35
Percentage of NetIncomeLoss101.5112.099.3102.1103.2113.6108.6102.8102.064.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.54.36.712.816.42.73.29.712.0-1.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value264951662991532378021126884
Percentage of NetIncomeLoss48.5126.7120.3104.2405.384.1137.998.1109.4-155.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.84.88.213.164.62.04.19.312.94.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value544751382873784458215245-54
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.23.86.812.615.92.43.09.511.8-2.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1591-151-371-854-2434-54-51-539-829338
Percentage of NetIncomeLoss-292.5-201.3-268.8-297.6-643.9-122.7-87.9-250.7-338.4-625.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-59.1-7.7-18.3-37.4-102.6-3.0-2.6-23.7-39.918.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4581072221332-18-5144
Percentage of NetIncomeLoss84.213.352.277.087.8-40.9-8.667.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.00.53.59.714.0-1.0-0.36.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value317-38-441180-15-87-37
Percentage of NetIncomeLoss58.3-50.7-2.914.347.6-34.1-150.0-17.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.8-1.9-0.21.87.6-0.8-4.4-1.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value751165276808861476-1247-11402402740485127724
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.30.50.30.20.10.40.30.40.00.40.30.30.10.20.30.6-0.10.20.40.7-0.10.10.40.00.20.40.00.20.70.50.00.50.80.60.10.30.70.80.30.5

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value75116527680
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.30.50.30.20.10.40.30.40.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

Assets

us-gaap:Assets



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value354263570335166358933238533041342133421232458322723277432232302533180132409330291883917813183191610515435152081655115828148001532315938158021511217003176081709115728166151723815847157521702015623
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value6290746481788099826488168586
Percentage of Assets17.820.923.322.625.526.726.5
Percentage of Assets17.820.923.322.625.526.726.5
Percentage of Assets srt:GuarantorSubsidiaries100.0100.0100.0100.0100.0100.0100.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value35260354263495235703322833280532201
Percentage of Assets99.599.299.499.599.799.399.2
Percentage of Assets99.599.299.499.599.799.399.2
Percentage of Assets srt:NonGuarantorSubsidiaries100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value10849104821069110685104461063610710
Percentage of Assets30.629.430.429.832.332.233.0
Percentage of Assets30.629.430.429.832.332.233.0
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-29481-30489-29295-29517-29719-30477-29973
Percentage of Assets-83.2-85.4-83.3-82.2-91.8-92.2-92.3
Percentage of Assets-83.2-85.4-83.3-82.2-91.8-92.2-92.3
Percentage of Assets srt:ConsolidationEliminations100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value399141593751398140354423
Percentage of Assets11.311.610.711.112.513.6
Percentage of Assets11.311.610.711.112.513.6
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc100.0100.0100.0100.0100.0100.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value851786616889694270766511
Percentage of Assets24.024.319.619.321.820.1
Percentage of Assets24.024.319.619.321.820.1
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc100.0100.0100.0100.0100.0100.0

Liabilities

us-gaap:Liabilities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value250572567224934256512238822851238392338222181221912233021775200192084721169216721642615275157781373313369129351408913356125571327613938139091338714305148971438713211138981456913239132541459113394
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets70.771.970.971.569.169.269.768.368.368.868.167.666.265.665.365.687.285.886.185.386.685.185.184.484.886.687.588.088.684.184.684.284.083.684.583.584.185.785.7

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value3599420847694719471240593934
Percentage of Liabilities14.416.419.118.421.017.817.7
Percentage of Assets10.211.813.613.114.512.312.1
Percentage of Assets srt:GuarantorSubsidiaries57.256.458.358.357.046.045.8

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value20552207712132121782183862117621675
Percentage of Liabilities82.080.985.584.982.192.797.7
Percentage of Assets58.058.260.660.756.864.166.8
Percentage of Assets srt:NonGuarantorSubsidiaries58.358.661.061.057.064.667.3

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value600595601595594587584
Percentage of Liabilities2.42.32.42.32.72.62.6
Percentage of Assets1.71.71.71.71.81.81.8
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities5.55.75.65.65.75.55.5

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-6169-6380-6661-6582-6489-8178-8942
Percentage of Liabilities-24.6-24.9-26.7-25.7-29.0-35.8-40.3
Percentage of Assets-17.4-17.9-18.9-18.3-20.0-24.8-27.5
Percentage of Assets srt:ConsolidationEliminations20.920.922.722.321.826.829.8

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value224823822177238322892916
Percentage of Liabilities9.09.38.79.310.213.1
Percentage of Assets6.36.76.26.67.19.0
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc56.357.358.059.956.765.9

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value422740962727275428962014
Percentage of Liabilities16.916.010.910.712.99.1
Percentage of Assets11.911.57.87.78.96.2
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc49.647.339.639.740.930.9

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value354263570335166358933238533041342133421232458322723277432232302533180132409330291883917813183191610515435152081655115828148001532315938158021511217003176081709115728166151723815847157521702015623
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value6290746481788099826488168586
Percentage of LiabilitiesAndStockholdersEquity17.820.923.322.625.526.726.5
Percentage of Assets17.820.923.322.625.526.726.5
Percentage of Assets srt:GuarantorSubsidiaries100.0100.0100.0100.0100.0100.0100.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value35260354263495235703322833280532201
Percentage of LiabilitiesAndStockholdersEquity99.599.299.499.599.799.399.2
Percentage of Assets99.599.299.499.599.799.399.2
Percentage of Assets srt:NonGuarantorSubsidiaries100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value10849104821069110685104461063610710
Percentage of LiabilitiesAndStockholdersEquity30.629.430.429.832.332.233.0
Percentage of Assets30.629.430.429.832.332.233.0
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-29481-30489-29295-29517-29719-30477-29973
Percentage of LiabilitiesAndStockholdersEquity-83.2-85.4-83.3-82.2-91.8-92.2-92.3
Percentage of Assets-83.2-85.4-83.3-82.2-91.8-92.2-92.3
Percentage of Assets srt:ConsolidationEliminations100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value399141593751398140354423
Percentage of LiabilitiesAndStockholdersEquity11.311.610.711.112.513.6
Percentage of Assets11.311.610.711.112.513.6
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc100.0100.0100.0100.0100.0100.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value851786616889694270766511
Percentage of LiabilitiesAndStockholdersEquity24.024.319.619.321.820.1
Percentage of Assets24.024.319.619.321.820.1
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc100.0100.0100.0100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value102499887100901009298521004910228106721012699151026310278100651076711050111512229239323932298198522582444244222152024197718651699267426872675248626882707263025772470240121801845
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets28.927.728.728.130.430.429.931.231.230.731.331.933.333.934.133.811.813.413.114.312.914.814.815.415.013.212.411.811.215.715.315.715.816.20.015.316.315.714.114.00.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value2691325634093380355247574652
Percentage of StockholdersEquity26.332.933.833.536.147.345.9
Percentage of Assets7.69.19.79.411.014.414.3
Percentage of Assets srt:GuarantorSubsidiaries42.843.641.741.743.054.054.2

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value14588145111348913771137521148810375
Percentage of StockholdersEquity142.3146.8133.7136.5139.6114.3102.5
Percentage of Assets41.240.638.438.442.534.832.0
Percentage of Assets srt:NonGuarantorSubsidiaries41.441.038.638.642.635.032.2

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value102499887100901009098521004910126
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets28.927.728.728.130.430.431.2
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities94.594.394.494.494.394.594.5

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-23312-24109-22634-22935-23230-22299-21031
Percentage of StockholdersEquity-227.5-243.8-224.3-227.3-235.8-221.9-207.7
Percentage of Assets-65.8-67.5-64.4-63.9-71.7-67.5-64.8
Percentage of Assets srt:ConsolidationEliminations79.179.177.377.778.273.270.2

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value174317771574159817461507
Percentage of StockholdersEquity17.018.015.615.817.714.9
Percentage of Assets4.95.04.54.55.44.6
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc43.742.742.040.143.334.1

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value429045654162418841804497
Percentage of StockholdersEquity41.946.241.241.542.444.4
Percentage of Assets12.112.811.811.712.913.9
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc50.452.760.460.359.169.1

us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value-1702-1360-1363-1370-1337-1073-1094-1132-1138-1122-1152-707-710-711-713-660-680-663-893-714
Percentage of StockholdersEquity-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-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:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-2227-2113-1993-1974-1961-1627-1605-1430-1513-1908-1884-1221-1181-1053-1037-954-872-952-1066-693-744-541-594-630-153
Percentage of StockholdersEquity-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-6.3-5.9-5.7-5.5-6.1-4.9-4.7-4.2-4.7-5.9-6.2-3.8-3.6-3.2-5.5-5.4-4.8-5.9-6.9-4.7-4.7-3.4-3.80.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value-538-746-626-607-616-550-506-307-365-724-650-434-398-310-314-302-230-296-191-14
Percentage of StockholdersEquity-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-1.5-2.1-1.8-1.7-1.9-1.7-1.5-0.9-1.1-2.2-2.1-1.4-1.2-0.9-1.7-1.7-1.3-1.8-1.2-0.1
Percentage of Assets us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent



Period End2019-12-312018-12-312017-12-312016-12-31
Value13-8-10-82
Percentage of StockholdersEquity0.1-0.1-0.1-0.8
Percentage of Assets0.0-0.0-0.0-0.3
Percentage of Assets us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent0.00.00.00.0

Assets Current

us-gaap:AssetsCurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312009-12-31
Value17037174001833319020164201675617889176061586115691162331579513792147331523015579125031233412946113281085310824120721144510461110141167411595108981211612726122171098711700123041110010975
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets48.148.752.153.050.750.752.351.548.948.649.549.045.646.347.047.266.469.270.770.370.371.272.972.370.771.973.273.472.171.372.371.569.970.471.470.070.2

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value40101930332545
Percentage of AssetsCurrent0.20.10.10.20.20.10.3
Percentage of Assets0.10.00.10.10.10.10.1
Percentage of Assets srt:GuarantorSubsidiaries0.60.10.20.40.40.30.5

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value16954172111821218921163491656615688
Percentage of AssetsCurrent99.598.999.399.599.698.998.9
Percentage of Assets47.948.251.852.750.550.148.3
Percentage of Assets srt:NonGuarantorSubsidiaries48.148.652.153.050.650.548.7

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0000002
Percentage of AssetsCurrent0.00.00.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.00.0
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-205-226-240-331-298-168-146
Percentage of AssetsCurrent-1.2-1.3-1.3-1.7-1.8-1.0-0.9
Percentage of Assets-0.6-0.6-0.7-0.9-0.9-0.5-0.4
Percentage of Assets srt:ConsolidationEliminations0.70.70.81.11.00.60.5

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1000000.00.00.01000000.01000000.01000000.0
Percentage of AssetsCurrent0.00.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.0
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value247405342399335271
Percentage of AssetsCurrent1.42.31.92.12.01.7
Percentage of Assets0.71.11.01.11.00.8
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc2.94.75.05.74.74.2

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302008-12-312007-12-31
Value88786781299210339319119541030912852901870767949954532466483503635656708734796623503531500424407464436363317432316141139222191203103176200
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.52.42.32.83.22.82.72.83.22.82.62.82.92.42.92.92.82.62.63.14.14.34.34.65.44.13.23.43.32.52.32.72.82.20.02.52.00.90.80.01.20.00.00.00.0

dei:LegalEntity

wltw:WillisLimited



Period End2019-12-31
Value140
Percentage of CashAndCashEquivalentsAtCarryingValue15.8
Percentage of Assets0.4
Percentage of Assets wltw:WillisLimited0.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312015-12-31
Value000000111502
Percentage of CashAndCashEquivalentsAtCarryingValue0.00.00.00.00.00.00.10.10.10.50.00.4
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312015-12-31
Value88786781299210339319099531027907870527
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.099.899.999.799.5100.099.1
Percentage of Assets2.52.42.32.83.22.82.72.83.22.82.92.8
Percentage of Assets srt:NonGuarantorSubsidiaries2.52.42.32.83.22.80.00.03.20.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-31
Value00000010200
Percentage of CashAndCashEquivalentsAtCarryingValue0.00.00.00.00.00.00.10.00.20.00.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.00.0

Accounts Receivable Net Current

us-gaap:AccountsReceivableNetCurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-012017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312009-12-31
Value262121672461249023792132239426002555224621552288230720802043218722681258110012261150104410211175118510419851044105193390810221009910911992839816
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.46.17.06.97.36.57.07.60.06.96.77.07.26.96.46.76.96.76.26.77.16.86.77.17.57.06.46.66.76.25.35.85.95.85.55.85.35.2

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value2582213924342462235521262242
Percentage of AccountsReceivableNetCurrent98.598.798.998.999.099.799.8
Percentage of Assets7.36.06.96.97.36.46.9
Percentage of Assets srt:NonGuarantorSubsidiaries7.36.07.06.97.36.57.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0.01000000.01000000.00.00.00.00.0
Percentage of AccountsReceivableNetCurrent0.00.00.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.00.0
Percentage of Assets srt:ConsolidationEliminations-0.0-0.0-0.0-0.0-0.0-0.0-0.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value39272628244
Percentage of AccountsReceivableNetCurrent1.51.21.11.11.00.2
Percentage of Assets0.10.10.10.10.10.0
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.50.30.40.40.30.1

Other Assets Current

us-gaap:OtherAssetsCurrent



Period End2019-12-312019-09-302019-06-302018-12-312018-09-302017-12-312017-09-302016-12-312016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312009-12-31
Value1128981576871675549255240222218214229195204197195207186181317309325259315369340198
Percentage of OtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.20.20.20.20.20.20.20.11.41.31.21.41.41.51.21.31.31.31.31.21.21.91.81.91.61.92.12.11.3

Prepaid Expense And Other Assets Current

us-gaap:PrepaidExpenseAndOtherAssetsCurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value525587451409404547458439430418342321337319327326255
Percentage of PrepaidExpenseAndOtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.51.61.31.11.21.71.31.31.31.31.01.01.11.01.01.01.4

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value40101930332544
Percentage of PrepaidExpenseAndOtherAssetsCurrent7.61.74.27.38.24.610.2
Percentage of Assets0.10.00.10.10.10.10.1
Percentage of Assets srt:GuarantorSubsidiaries0.60.10.20.40.40.30.5

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value481426357338357363264
Percentage of PrepaidExpenseAndOtherAssetsCurrent91.672.679.282.688.466.461.4
Percentage of Assets1.41.21.00.91.11.10.8
Percentage of Assets srt:NonGuarantorSubsidiaries1.41.21.00.91.11.10.8

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-205-227-241-331-298-168-146
Percentage of PrepaidExpenseAndOtherAssetsCurrent-39.0-38.7-53.4-80.9-73.8-30.7-34.0
Percentage of Assets-0.6-0.6-0.7-0.9-0.9-0.5-0.4
Percentage of Assets srt:ConsolidationEliminations0.70.70.81.11.00.60.5

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1000000.00.00.01000000.01000000.01000000.0
Percentage of PrepaidExpenseAndOtherAssetsCurrent0.20.00.00.20.20.2
Percentage of Assets0.00.00.00.00.00.0
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value208378316371311267
Percentage of PrepaidExpenseAndOtherAssetsCurrent39.664.470.190.777.062.1
Percentage of Assets0.61.10.91.01.00.8
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc2.44.44.65.34.44.1

Noncurrent Assets

us-gaap:NoncurrentAssets



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value1831715906165511641162604563
Percentage of NoncurrentAssets100.0100.0100.0100.0100.0100.0
Percentage of Assets51.749.151.054.233.229.6

us-gaap:StatementGeographical

country:GB



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value290123493173243124261666233218
Percentage of NoncurrentAssets15.814.819.214.838.836.50.00.0
Percentage of Assets8.27.39.88.012.910.81.61.4
Percentage of Assets country:GB0.00.00.00.00.00.00.00.0

country:IE



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value10378127114124121
Percentage of NoncurrentAssets0.60.50.80.72.02.7
Percentage of Assets0.30.20.40.40.70.8
Percentage of Assets country:IE0.00.00.00.00.00.0

country:US



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value127861106899881140017591800203207
Percentage of NoncurrentAssets69.869.660.369.528.139.40.00.0
Percentage of Assets36.134.230.837.79.311.71.41.4
Percentage of Assets country:US0.00.00.00.00.00.00.00.0

wltw:ForeignCountries



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value1821415828164241629761364442
Percentage of NoncurrentAssets99.499.599.299.398.097.3
Percentage of Assets51.448.950.653.932.628.8
Percentage of Assets wltw:ForeignCountries0.00.00.00.00.00.0

wltw:RestOfWorld



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value25272411326324661951976
Percentage of NoncurrentAssets13.815.219.715.031.221.4
Percentage of Assets7.17.410.18.210.46.3
Percentage of Assets wltw:RestOfWorld0.00.00.00.00.00.0

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value19421710186214811091980949881792753708
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.55.35.74.95.86.36.45.85.04.84.5

us-gaap:PropertyPlantAndEquipmentByType

us-gaap:FurnitureAndFixtures



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value1302113013001009724642618576509488473
Percentage of PropertyPlantAndEquipmentGross67.066.169.868.166.465.565.165.464.364.866.8
Percentage of Assets3.73.54.03.33.84.24.23.83.23.13.0
Percentage of Assets us-gaap:FurnitureAndFixtures0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LandAndBuilding



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value9092949095938978737351
Percentage of PropertyPlantAndEquipmentGross4.65.45.06.18.79.59.48.99.29.77.2
Percentage of Assets0.30.30.30.30.50.60.60.50.50.50.3
Percentage of Assets us-gaap:LandAndBuilding0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LeaseholdImprovements



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value550488468382272245242227210192184
Percentage of PropertyPlantAndEquipmentGross28.328.525.125.824.925.025.525.826.525.526.0
Percentage of Assets1.61.51.41.31.41.61.61.51.31.21.2
Percentage of Assets us-gaap:LeaseholdImprovements0.00.00.00.00.00.00.00.00.00.00.0

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312010-09-302010-06-302009-12-31
Value896768877642528497468413386372277253257
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.52.42.72.12.83.23.22.72.52.31.81.51.6

us-gaap:PropertyPlantAndEquipmentByType

us-gaap:FurnitureAndFixtures



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value594519652464393366345306297291286
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment66.367.674.372.374.473.673.774.176.978.2111.3
Percentage of Assets1.71.62.01.52.12.42.32.01.91.81.8
Percentage of Assets us-gaap:FurnitureAndFixtures0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LandAndBuilding



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value5752494141383632282524
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment6.46.85.66.47.87.67.77.77.36.79.3
Percentage of Assets0.20.20.20.10.20.20.20.20.20.20.2
Percentage of Assets us-gaap:LandAndBuilding0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LeaseholdImprovements



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value24519717613794938775615646
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment27.325.720.121.317.818.718.618.215.815.117.9
Percentage of Assets0.70.60.50.50.50.60.60.50.40.40.3
Percentage of Assets us-gaap:LeaseholdImprovements0.00.00.00.00.00.00.00.00.00.00.0

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value1046963967957942944924926985937895863839811794790563531516462483481496482481472452447468446428426406387386381356346352
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.02.72.72.72.92.92.72.73.02.92.72.72.82.62.42.43.03.02.82.93.13.23.03.03.23.12.82.83.12.62.42.52.62.32.22.42.32.02.3

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value17171717162625
Percentage of PropertyPlantAndEquipmentNet1.61.81.81.81.72.82.5
Percentage of Assets0.00.00.00.00.00.10.1
Percentage of Assets srt:GuarantorSubsidiaries0.30.20.20.20.20.30.3

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1028946950940926918960
Percentage of PropertyPlantAndEquipmentNet98.398.298.298.298.397.297.5
Percentage of Assets2.92.62.72.62.92.83.0
Percentage of Assets srt:NonGuarantorSubsidiaries2.92.72.72.62.92.83.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1000000.00.00.00.00.00.0
Percentage of PropertyPlantAndEquipmentNet0.10.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.0
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.0

us-gaap:PropertyPlantAndEquipmentByType

us-gaap:FurnitureAndFixtures



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value708611648545331276273270212197
Percentage of PropertyPlantAndEquipmentNet67.764.965.865.058.857.156.857.752.251.7
Percentage of Assets2.01.92.01.81.81.81.81.81.31.2
Percentage of Assets us-gaap:FurnitureAndFixtures0.00.00.00.00.00.00.00.00.00.0

us-gaap:LandAndBuilding



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value33404549545553464548
Percentage of PropertyPlantAndEquipmentNet3.24.24.65.89.611.411.09.811.112.6
Percentage of Assets0.10.10.10.20.30.40.40.30.30.3
Percentage of Assets us-gaap:LandAndBuilding0.00.00.00.00.00.00.00.00.00.0

us-gaap:LeaseholdImprovements



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value305291292245178152155152149136
Percentage of PropertyPlantAndEquipmentNet29.230.929.629.231.631.532.232.536.735.7
Percentage of Assets0.90.90.90.80.91.01.01.00.90.9
Percentage of Assets us-gaap:LeaseholdImprovements0.00.00.00.00.00.00.00.00.00.0

Investments In Affiliates Subsidiaries Associates And Joint Ventures

us-gaap:ConsolidatedEntities

us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value6097733480387947810886828425
Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets17.220.522.922.125.026.326.0
Percentage of Assets srt:GuarantorSubsidiaries96.998.398.398.198.198.598.1

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value6205586055805952569144524506
Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures101.879.969.474.970.251.353.5
Percentage of Assets17.516.415.916.617.613.513.9
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities57.255.952.255.754.541.942.1

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-23197-24006-22527-22826-23125-22206-20974
Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures-380.5-327.3-280.3-287.2-285.2-255.8-248.9
Percentage of Assets-65.5-67.2-64.1-63.6-71.4-67.2-64.6
Percentage of Assets srt:ConsolidationEliminations78.778.776.977.377.872.970.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value279226952503252626771918
Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures45.836.731.131.833.022.8
Percentage of Assets7.97.57.17.08.35.9
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc70.064.866.763.566.343.4

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value810381176406640166496125
Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures132.9110.779.780.582.072.7
Percentage of Assets22.922.718.217.820.518.9
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc95.193.793.092.294.094.1

Goodwill

us-gaap:Goodwill



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value1119411187104541045610465104571046810555105191052910509104421041310483105271047737373150309728892937280328702835283828462829281328273304329833083295329733123294327532713277
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets31.631.329.729.132.331.630.630.932.432.632.132.434.433.032.531.719.817.716.917.919.018.417.317.919.218.617.817.818.719.418.719.420.919.819.220.820.819.221.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value11194111871045410456104651045710519
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets31.631.329.729.132.331.632.4
Percentage of Assets srt:NonGuarantorSubsidiaries31.731.629.929.332.431.932.7

us-gaap:StatementBusinessSegments

wltw:BenefitsDeliveryAndAdministration



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312016-12-31
Value32843342255725572557255725572557
Percentage of Goodwill29.329.924.524.524.424.524.324.6
Percentage of Assets9.39.47.37.17.97.77.98.5
Percentage of Assets wltw:BenefitsDeliveryAndAdministration0.00.00.00.00.00.00.00.0

wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312016-12-31
Value19471912193819391946194618991816
Percentage of Goodwill17.417.118.518.518.618.618.117.4
Percentage of Assets5.55.45.55.46.05.95.96.0
Percentage of Assets wltw:CorporateRiskAndBroking0.00.00.00.00.00.00.00.0

wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312016-12-31
Value41684137416541644170418142124282
Percentage of Goodwill37.237.039.839.839.840.040.041.1
Percentage of Assets11.811.611.811.612.912.713.014.2
Percentage of Assets wltw:HumanCapitalAndBenefits0.00.00.00.00.00.00.00.0

wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312016-12-31
Value17951796179417961792177318511758
Percentage of Goodwill16.016.117.217.217.117.017.616.9
Percentage of Assets5.15.05.15.05.55.45.75.8
Percentage of Assets wltw:InvestmentRiskAndReinsurance0.00.00.00.00.00.00.00.0

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value34783561305531873318342935623761388240344156424543684589471350861115
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets9.810.08.78.910.210.410.411.012.012.512.713.214.414.414.515.45.9

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value69565657585860
Percentage of IntangibleAssetsNetExcludingGoodwill2.01.61.81.81.71.71.5
Percentage of Assets0.20.20.20.20.20.20.2
Percentage of Assets srt:GuarantorSubsidiaries1.10.80.70.70.70.70.7

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value3492356130553187331834293882
Percentage of IntangibleAssetsNetExcludingGoodwill100.4100.0100.0100.0100.0100.0100.0
Percentage of Assets9.910.08.78.910.210.412.0
Percentage of Assets srt:NonGuarantorSubsidiaries9.910.18.78.910.310.512.1

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-83-56-56-57-58-58-60
Percentage of IntangibleAssetsNetExcludingGoodwill-2.4-1.6-1.8-1.8-1.7-1.7-1.5
Percentage of Assets-0.2-0.2-0.2-0.2-0.2-0.2-0.2
Percentage of Assets srt:ConsolidationEliminations0.30.20.20.20.20.20.2

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value34783561305531873318342935623761388240344156424543324553464949951115665675418450331360339353361373369385379391406420440477492507528572
Percentage of FiniteLivedIntangibleAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets9.810.08.78.910.210.410.411.012.012.512.713.214.314.314.315.15.93.73.72.62.92.22.22.12.42.42.32.32.52.22.22.42.72.62.83.13.23.13.7

us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-31
Value2298234818221909198620472131226323422446252725812655280928563057920581588349373326353334345352364362377374387403417437488
Percentage of FiniteLivedIntangibleAssetsNet66.165.959.659.959.959.759.860.260.360.660.860.861.361.761.461.282.587.487.183.582.998.598.198.597.797.597.698.197.998.799.099.399.399.399.2
Percentage of Assets6.56.65.25.36.16.26.26.67.27.67.78.08.88.88.89.34.93.33.22.22.42.12.12.12.32.32.32.32.52.22.22.42.72.63.1
Percentage of Assets us-gaap:CustomerRelationships0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OffMarketFavorableLease



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312016-12-31
Value000091011
Percentage of FiniteLivedIntangibleAssetsNet0.00.00.00.00.30.30.3
Percentage of Assets0.00.00.00.00.00.00.0
Percentage of Assets us-gaap:OffMarketFavorableLease0.00.00.00.00.00.00.0

us-gaap:OtherIntangibleAssets



Period End2019-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-31
Value10301122233334513321236722
Percentage of FiniteLivedIntangibleAssetsNet3.00.00.00.00.10.10.00.10.10.10.10.10.111.93.23.41.41.60.60.5
Percentage of Assets0.30.00.00.00.00.00.00.00.00.00.00.00.00.70.10.10.00.00.00.0
Percentage of Assets us-gaap:OtherIntangibleAssets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:SoftwareAndSoftwareDevelopmentCosts



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value20223126329832836339744247350854056857061665076877
Percentage of FiniteLivedIntangibleAssetsNet5.86.58.69.49.910.611.111.812.212.613.013.413.213.514.015.46.9
Percentage of Assets0.60.60.70.81.01.11.21.31.51.61.61.81.91.92.02.30.4
Percentage of Assets us-gaap:SoftwareAndSoftwareDevelopmentCosts0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TrademarksAndTradeNames



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value8758848989099209309439579669769879961006102010311044503
Percentage of FiniteLivedIntangibleAssetsNet25.224.829.428.527.727.126.525.424.924.223.723.523.222.422.220.94.50.7
Percentage of Assets2.52.52.62.52.82.82.82.83.03.03.03.13.33.23.23.20.30.0
Percentage of Assets us-gaap:TrademarksAndTradeNames0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Deferred Tax Assets Liabilities Net

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312009-12-31
Value835701541494467500468532447432386351353328330348209211234229220196194209206187205199206328360353283339357233221
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.42.01.51.41.41.51.41.61.41.31.21.11.21.01.01.11.11.21.31.41.41.31.21.31.41.21.31.31.41.92.02.11.82.02.11.51.4

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value67474848492531
Percentage of OtherAssetsNoncurrent8.06.78.99.710.55.06.9
Percentage of Assets0.20.10.10.10.20.10.1
Percentage of Assets srt:GuarantorSubsidiaries1.10.60.60.60.60.30.4

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value756630465420452480388
Percentage of OtherAssetsNoncurrent90.589.986.085.096.896.086.8
Percentage of Assets2.11.81.31.21.41.51.2
Percentage of Assets srt:NonGuarantorSubsidiaries2.11.81.31.21.41.51.2

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0000060
Percentage of OtherAssetsNoncurrent0.00.00.00.00.01.20.0
Percentage of Assets0.00.00.00.00.00.00.0
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.10.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-155-117-115-118-128-86-90
Percentage of OtherAssetsNoncurrent-18.6-16.7-21.3-23.9-27.4-17.2-20.1
Percentage of Assets-0.4-0.3-0.3-0.3-0.4-0.3-0.3
Percentage of Assets srt:ConsolidationEliminations0.50.40.40.40.40.30.3

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value122223
Percentage of OtherAssetsNoncurrent0.10.30.40.40.40.7
Percentage of Assets0.00.00.00.00.00.0
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.10.10.00.1

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value16613914114292115
Percentage of OtherAssetsNoncurrent19.919.826.128.719.725.7
Percentage of Assets0.50.40.40.40.30.4
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc1.91.62.02.01.31.8

Liabilities Current

us-gaap:LiabilitiesCurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312009-12-31
Value160701673617204176541530115555163821580414755145561502914585133701421714417152561280111881124951054810232100051098410276947410135107651067110194110861164911091999610820113581030910498
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets45.446.948.949.247.247.147.946.245.545.145.945.344.244.744.546.267.966.768.265.566.365.866.464.964.066.167.567.567.565.266.264.963.665.165.965.167.2

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value619118161634
Percentage of LiabilitiesCurrent0.00.10.10.00.10.10.2
Percentage of Assets0.00.10.00.00.00.00.1
Percentage of Assets srt:GuarantorSubsidiaries0.10.30.10.10.20.20.4

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value15754162891703217594151801553014649
Percentage of LiabilitiesCurrent98.097.399.099.799.299.899.3
Percentage of Assets44.545.648.449.046.947.045.1
Percentage of Assets srt:NonGuarantorSubsidiaries44.746.048.749.347.047.345.5

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1019710397969087
Percentage of LiabilitiesCurrent0.60.60.60.50.60.60.6
Percentage of Assets0.30.30.30.30.30.30.3
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities0.90.91.00.90.90.80.8

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-174-179-191-279-250-116-150
Percentage of LiabilitiesCurrent-1.1-1.1-1.1-1.6-1.6-0.7-1.0
Percentage of Assets-0.5-0.5-0.5-0.8-0.8-0.4-0.5
Percentage of Assets srt:ConsolidationEliminations0.60.60.70.90.80.40.5

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value13128327193333
Percentage of LiabilitiesCurrent0.81.70.20.10.20.2
Percentage of Assets0.40.80.10.10.10.1
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc3.36.80.70.50.80.7

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value252227222215226102
Percentage of LiabilitiesCurrent1.61.41.31.21.50.7
Percentage of Assets0.70.60.60.60.70.3
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc3.02.63.23.13.21.6

Debt Current

Long Term Debt Current

us-gaap:LongTermDebtCurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value316484187187186
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0
Percentage of Assets0.91.40.50.50.6

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value2421000
Percentage of LongTermDebtCurrent7.64.30.00.00.0
Percentage of Assets0.10.10.00.00.0
Percentage of Assets srt:NonGuarantorSubsidiaries0.10.10.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value95267000
Percentage of LongTermDebtCurrent30.155.20.00.00.0
Percentage of Assets0.30.70.00.00.0
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc2.46.40.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value197196187187186
Percentage of LongTermDebtCurrent62.340.5100.0100.0100.0
Percentage of Assets0.60.50.50.50.6
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc2.32.32.72.72.6

us-gaap:DebtInstrument

wltw:SeniorNotesDue20190700



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value00187187186
Percentage of LongTermDebtCurrent0.00.0100.0100.0100.0
Percentage of Assets0.00.00.50.50.6
Percentage of Assets wltw:SeniorNotesDue201907000.00.00.00.00.0

wltw:TermLoanDueDecember2020



Period End2019-12-312019-09-302018-12-31
Value2924630
Percentage of LongTermDebtCurrent92.495.70.0
Percentage of Assets0.81.30.0
Percentage of Assets wltw:TermLoanDueDecember20200.00.00.0

us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value316484187187186
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0
Percentage of Assets0.91.40.50.50.6
Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure us-gaap:FairValueMeasurementsNonrecurring0.00.00.00.00.0

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value319488188190191
Percentage of LongTermDebtCurrent100.9100.8100.5101.6102.7
Percentage of Assets0.91.40.50.50.6
Percentage of Assets us-gaap:EstimateOfFairValueFairValueDisclosure us-gaap:FairValueMeasurementsNonrecurring0.00.00.00.00.0

Accounts Payable Current

Other Accrued Liabilities Current

Taxes Payable Current

us-gaap:TaxesPayableCurrent



Period End2019-12-312019-09-302018-12-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value13816512990179917912913645
Percentage of TaxesPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.50.40.30.60.30.20.40.40.2

Accrued Income Taxes Current

Other Liabilities Current

us-gaap:OtherLiabilitiesCurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312009-12-31
Value802801810940864758814867804793882996876812901972558488522461444445467495415381358333327289297334282274343266278
Percentage of OtherLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.32.22.32.62.72.32.42.52.52.52.73.12.92.62.82.93.02.72.82.92.92.92.83.12.82.52.22.12.21.71.72.01.81.62.01.71.8

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value317115131127
Percentage of OtherLiabilitiesCurrent0.42.11.40.51.51.53.4
Percentage of Assets0.00.00.00.00.00.00.1
Percentage of Assets srt:GuarantorSubsidiaries0.00.20.10.10.20.10.3

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value7708228261070935739724
Percentage of OtherLiabilitiesCurrent96.0102.6102.0113.8108.297.590.0
Percentage of Assets2.22.32.33.02.92.22.2
Percentage of Assets srt:NonGuarantorSubsidiaries2.22.32.43.02.92.32.2

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1019710397958987
Percentage of OtherLiabilitiesCurrent12.612.112.710.311.011.710.8
Percentage of Assets0.30.30.30.30.30.30.3
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities0.90.91.00.90.90.80.8

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-160-179-191-279-250-116-150
Percentage of OtherLiabilitiesCurrent-20.0-22.3-23.6-29.7-28.9-15.3-18.7
Percentage of Assets-0.5-0.5-0.5-0.8-0.8-0.4-0.5
Percentage of Assets srt:ConsolidationEliminations0.50.60.70.90.80.40.5

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value361627193333
Percentage of OtherLiabilitiesCurrent4.52.03.32.03.84.1
Percentage of Assets0.10.00.10.10.10.1
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.90.40.70.50.80.7

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value522834283883
Percentage of OtherLiabilitiesCurrent6.53.54.23.04.410.3
Percentage of Assets0.10.10.10.10.10.3
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.60.30.50.40.51.3

Dividends Payable Current

us-gaap:DividendsPayableCurrent



Period End2019-12-312018-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-31
Value10087586558555455555150504847484749464546
Percentage of DividendsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.30.30.40.40.40.40.30.30.30.30.30.30.30.30.30.30.30.30.3

Liabilities Noncurrent

us-gaap:LiabilitiesNoncurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312009-12-31
Value8987893677307997708772967457757874267635730171906649663067526416362533943283318531372930310530803083314131733238319332193248329632153078321129302898
Percentage of LiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets25.425.022.022.321.922.121.822.222.923.722.322.322.020.820.819.419.219.117.919.820.319.318.819.520.820.519.920.521.118.918.419.320.418.518.618.518.5

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value3593418947584711469640433900
Percentage of LiabilitiesNoncurrent40.046.961.658.966.355.452.5
Percentage of Assets10.111.713.513.114.512.212.0
Percentage of Assets srt:GuarantorSubsidiaries57.156.158.258.256.845.945.4

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value4798448242894188320656467026
Percentage of LiabilitiesNoncurrent53.450.255.552.445.277.494.6
Percentage of Assets13.512.612.211.79.917.121.6
Percentage of Assets srt:NonGuarantorSubsidiaries13.612.712.311.79.917.221.8

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value499498498498498497497
Percentage of LiabilitiesNoncurrent5.65.66.46.27.06.86.7
Percentage of Assets1.41.41.41.41.51.51.5
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities4.64.84.74.74.84.74.6

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-5995-6201-6470-6303-6239-8062-8792
Percentage of LiabilitiesNoncurrent-66.7-69.4-83.7-78.8-88.0-110.5-118.4
Percentage of Assets-16.9-17.4-18.4-17.6-19.3-24.4-27.1
Percentage of Assets srt:ConsolidationEliminations20.320.322.121.421.026.529.3

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value211720992150236422562883
Percentage of LiabilitiesNoncurrent23.623.527.829.631.838.8
Percentage of Assets6.05.96.16.67.08.9
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc53.050.557.359.455.965.2

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value397538692505253926701912
Percentage of LiabilitiesNoncurrent44.243.332.431.737.725.7
Percentage of Assets11.210.87.17.18.25.9
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc46.744.736.436.637.729.4

Long Term Debt

us-gaap:LongTermDebt



Period End2019-12-312018-12-312017-12-312016-12-312010-09-302010-06-302009-12-31
Value8017640056384943220221542165
Percentage of LongTermDebt100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets22.619.817.416.314.012.713.9

us-gaap:CreditFacility, us-gaap:DebtInstrument, dei:LegalEntity

us-gaap:RevolvingCreditFacility, wltw:Revolving125BillionDollarCreditFacility, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-31
Value09025269
Percentage of LongTermDebt0.00.00.00.0
Percentage of Assets0.00.30.10.7
Percentage of Assets us-gaap:RevolvingCreditFacility wltw:Revolving125BillionDollarCreditFacility wltw:TrinityAcquisitionPlc0.00.00.00.0

us-gaap:CreditFacility, us-gaap:DebtInstrument, us-gaap:LongtermDebtType

us-gaap:RevolvingCreditFacility, wltw:RevolvingOnePointTwoFiveBillionDollarCreditFacility, us-gaap:LineOfCredit



Period End2019-12-31
Value0.0
Percentage of LongTermDebt0.0
Percentage of Assets0.0
Percentage of Assets us-gaap:RevolvingCreditFacility wltw:RevolvingOnePointTwoFiveBillionDollarCreditFacility us-gaap:LineOfCredit0.0

us-gaap:DebtInstrument

wltw:CollateralizedFacility



Period End2019-12-31
Value79
Percentage of LongTermDebt1.0
Percentage of Assets0.2
Percentage of Assets wltw:CollateralizedFacility0.0

wltw:TermLoanDueDecember2020



Period End2019-12-31
Value295
Percentage of LongTermDebt3.7
Percentage of Assets0.8
Percentage of Assets wltw:TermLoanDueDecember20200.0

us-gaap:DebtInstrument, dei:LegalEntity

wltw:TermLoan, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-30
Value95267
Percentage of LongTermDebt1.20.0
Percentage of Assets0.30.7
Percentage of Assets wltw:TermLoan wltw:TrinityAcquisitionPlc0.00.0

us-gaap:DebtInstrument, us-gaap:LongtermDebtType

wltw:InterestOnSeniorNotes, us-gaap:SeniorNotes



Period End2019-12-312017-12-312016-12-31
Value236210781049
Percentage of LongTermDebt29.519.121.2
Percentage of Assets6.73.33.5
Percentage of Assets wltw:InterestOnSeniorNotes us-gaap:SeniorNotes0.00.00.0

us-gaap:LongtermDebtType

us-gaap:SeniorNotes



Period End2019-12-312018-12-312017-12-312016-12-31
Value5281447935063176
Percentage of LongTermDebt65.970.062.264.3
Percentage of Assets14.913.810.810.5
Percentage of Assets us-gaap:SeniorNotes0.00.00.00.0

us-gaap:LongtermDebtType, dei:LegalEntity

us-gaap:SeniorNotes, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312016-05-262016-03-222013-08-15
Value21002100210021005401000525
Percentage of LongTermDebt26.20.00.00.00.00.00.0
Percentage of Assets5.95.96.05.90.00.00.0
Percentage of Assets us-gaap:SeniorNotes wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.0

us-gaap:SeniorNotes, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-09-102019-06-302019-03-312018-12-312018-09-102017-05-162009-09-29
Value2700270010001800180018001000650187
Percentage of LongTermDebt33.70.00.00.00.028.10.00.00.0
Percentage of Assets7.67.60.05.15.05.60.00.00.0
Percentage of Assets us-gaap:SeniorNotes wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.00.0

Long Term Debt Noncurrent

us-gaap:LongTermDebtNoncurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312009-12-31
Value5301538142844518438944984589450744504493409739753357326732812767227822482052213721422148230223072311231523262387233823642397243523542285243221572165
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets15.015.112.212.613.613.613.413.213.713.912.512.311.110.310.18.412.112.611.213.313.914.113.914.615.615.114.615.115.513.913.614.215.013.814.113.613.9

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value6070510-18684
Percentage of LongTermDebtNoncurrent1.11.30.10.00.0-4.11.9
Percentage of Assets0.20.20.00.00.0-0.60.3
Percentage of Assets srt:NonGuarantorSubsidiaries0.20.20.00.00.0-0.60.3

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value499498498498498497497
Percentage of LongTermDebtNoncurrent9.49.311.611.011.311.011.2
Percentage of Assets1.41.41.41.41.51.51.5
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities4.64.84.74.74.84.74.6

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value211720992150236422562883
Percentage of LongTermDebtNoncurrent39.939.050.252.351.464.8
Percentage of Assets6.05.96.16.67.08.9
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc53.050.557.359.455.965.2

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value26252714163116551635986
Percentage of LongTermDebtNoncurrent49.550.438.136.637.322.2
Percentage of Assets7.47.64.64.65.03.0
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc30.831.323.723.823.115.1

us-gaap:CreditFacility, us-gaap:DebtInstrument

us-gaap:RevolvingCreditFacility, wltw:Revolving125BillionDollarCreditFacility



Period End2019-12-312019-09-302018-12-31
Value090130
Percentage of LongTermDebtNoncurrent0.01.73.0
Percentage of Assets0.00.30.4
Percentage of Assets us-gaap:RevolvingCreditFacility wltw:Revolving125BillionDollarCreditFacility0.00.00.0

us-gaap:DebtInstrument

wltw:SeniorNotesDue202103500



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value448448448448448448447
Percentage of LongTermDebtNoncurrent8.58.310.59.910.210.010.0
Percentage of Assets1.31.31.31.21.41.41.4
Percentage of Assets wltw:SeniorNotesDue2021035000.00.00.00.00.00.00.0

wltw:SeniorNotesDue202105750



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value499498498498498497497
Percentage of LongTermDebtNoncurrent9.49.311.611.011.311.011.2
Percentage of Assets1.41.41.41.41.51.51.5
Percentage of Assets wltw:SeniorNotesDue2021057500.00.00.00.00.00.00.0

wltw:SeniorNotesDue202202125



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value604587612604615625644
Percentage of LongTermDebtNoncurrent11.410.914.313.414.013.914.5
Percentage of Assets1.71.61.71.71.91.92.0
Percentage of Assets wltw:SeniorNotesDue2022021250.00.00.00.00.00.00.0

wltw:SeniorNotesDue202304625



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value249248248248248248248
Percentage of LongTermDebtNoncurrent4.74.65.85.55.75.55.6
Percentage of Assets0.70.70.70.70.80.80.8
Percentage of Assets wltw:SeniorNotesDue2023046250.00.00.00.00.00.00.0

wltw:SeniorNotesDue202403600



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value646646646646645645645
Percentage of LongTermDebtNoncurrent12.212.015.114.314.714.314.5
Percentage of Assets1.81.81.81.82.02.02.0
Percentage of Assets wltw:SeniorNotesDue2024036000.00.00.00.00.00.00.0

wltw:SeniorNotesDue202604400



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value546546546544544544544
Percentage of LongTermDebtNoncurrent10.310.112.712.012.412.112.2
Percentage of Assets1.51.51.61.51.71.61.7
Percentage of Assets wltw:SeniorNotesDue2026044000.00.00.00.00.00.00.0

wltw:SeniorNotesDue202902950



Period End2019-12-312019-09-302018-12-31
Value4464460
Percentage of LongTermDebtNoncurrent8.48.30.0
Percentage of Assets1.31.20.0
Percentage of Assets wltw:SeniorNotesDue2029029500.00.00.0

wltw:SeniorNotesDue204903875



Period End2019-12-312019-09-302018-12-31
Value5425420
Percentage of LongTermDebtNoncurrent10.210.10.0
Percentage of Assets1.51.50.0
Percentage of Assets wltw:SeniorNotesDue2049038750.00.00.0

us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

us-gaap:CarryingReportedAmountFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value53015381428445184389
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0
Percentage of Assets15.015.112.212.613.6
Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure us-gaap:FairValueMeasurementsNonrecurring0.00.00.00.00.0

us-gaap:EstimateOfFairValueFairValueDisclosure, us-gaap:FairValueMeasurementsNonrecurring



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value56945764459347214458
Percentage of LongTermDebtNoncurrent107.4107.1107.2104.5101.6
Percentage of Assets16.116.113.113.213.8
Percentage of Assets us-gaap:EstimateOfFairValueFairValueDisclosure us-gaap:FairValueMeasurementsNonrecurring0.00.00.00.00.0

Deferred Tax Liabilities Noncurrent

Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value1324103911251135117010871185123012591207127112861321108911601210279
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.72.93.23.23.63.33.53.63.93.73.94.04.43.43.63.71.5

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1324103911251135117010871259
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.72.93.23.23.63.33.9
Percentage of Assets srt:NonGuarantorSubsidiaries3.82.93.23.23.63.33.9

us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

country:GB, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312018-12-312017-12-31
Value789
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent0.50.70.7
Percentage of Assets0.00.00.0
Percentage of Assets country:GB us-gaap:PensionPlansDefinedBenefit0.00.00.0

country:US, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312018-12-312017-12-31
Value862735782
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent65.162.862.1
Percentage of Assets2.42.32.4
Percentage of Assets country:US us-gaap:PensionPlansDefinedBenefit0.00.00.0

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312018-12-312017-12-31
Value270253271
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent20.421.621.5
Percentage of Assets0.80.80.8
Percentage of Assets wltw:OtherForeignPlans us-gaap:PensionPlansDefinedBenefit0.00.00.0

us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit



Period End2019-12-312018-12-312017-12-31
Value8481116
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent6.36.99.2
Percentage of Assets0.20.30.4
Percentage of Assets us-gaap:OtherPostretirementBenefitPlansDefinedBenefit0.00.00.0

Minority Interest

us-gaap:MinorityInterest



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value120114114122119114119130123111124126118134138153131939623221518302823232826242429312932393128284950
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.30.30.30.40.30.30.40.40.30.40.40.40.40.40.50.70.50.50.10.10.10.10.20.20.20.10.20.20.10.10.20.20.20.00.20.20.20.20.30.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value120114114122119114123
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.30.30.30.40.30.4
Percentage of Assets srt:NonGuarantorSubsidiaries0.30.30.30.30.40.30.4

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312009-12-31
Value335314299296429448446506544476473512532544561605533502506398389347362354374353371378375376381371363362371347294
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.90.90.90.81.31.41.31.51.71.51.41.61.81.71.71.82.82.82.82.52.52.32.22.22.52.32.32.42.52.22.22.22.32.22.22.21.9

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0542525
Percentage of OtherLiabilitiesNoncurrent0.01.61.30.71.20.40.9
Percentage of Assets0.00.00.00.00.00.00.0
Percentage of Assets srt:GuarantorSubsidiaries0.00.10.00.00.10.00.1

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value311291278278411445520
Percentage of OtherLiabilitiesNoncurrent92.892.793.093.995.899.395.6
Percentage of Assets0.90.80.80.81.31.31.6
Percentage of Assets srt:NonGuarantorSubsidiaries0.90.80.80.81.31.41.6

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value241817161319
Percentage of OtherLiabilitiesNoncurrent7.25.75.75.43.03.5
Percentage of Assets0.10.10.00.00.00.1
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.30.20.20.20.20.3

Stockholders Equity

us-gaap:StockholdersEquity



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value102499887100901009298521004910228106721012699151026310278100651076711050111512229239323932298198522582444244222152024197718651699267426872675248626882707263025772470240121801845
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets28.927.728.728.130.430.429.931.231.230.731.331.933.333.934.133.811.813.413.114.312.914.814.815.415.013.212.411.811.215.715.315.715.816.20.015.316.315.714.114.00.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value2691325634093380355247574652
Percentage of StockholdersEquity26.332.933.833.536.147.345.9
Percentage of Assets7.69.19.79.411.014.414.3
Percentage of Assets srt:GuarantorSubsidiaries42.843.641.741.743.054.054.2

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value14588145111348913771137521148810375
Percentage of StockholdersEquity142.3146.8133.7136.5139.6114.3102.5
Percentage of Assets41.240.638.438.442.534.832.0
Percentage of Assets srt:NonGuarantorSubsidiaries41.441.038.638.642.635.032.2

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value102499887100901009098521004910126
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets28.927.728.728.130.430.431.2
Percentage of Assets srt:ParentCompany srt:ReportableLegalEntities94.594.394.494.494.394.594.5

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-23312-24109-22634-22935-23230-22299-21031
Percentage of StockholdersEquity-227.5-243.8-224.3-227.3-235.8-221.9-207.7
Percentage of Assets-65.8-67.5-64.4-63.9-71.7-67.5-64.8
Percentage of Assets srt:ConsolidationEliminations79.179.177.377.778.273.270.2

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value174317771574159817461507
Percentage of StockholdersEquity17.018.015.615.817.714.9
Percentage of Assets4.95.04.54.55.44.6
Percentage of Assets srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc43.742.742.040.143.334.1

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value429045654162418841804497
Percentage of StockholdersEquity41.946.241.241.542.444.4
Percentage of Assets12.112.811.811.712.913.9
Percentage of Assets srt:ReportableLegalEntities wltw:WillisNorthAmericaInc50.452.760.460.359.169.1

us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value-1702-1360-1363-1370-1337-1073-1094-1132-1138-1122-1152-707-710-711-713-660-680-663-893-714
Percentage of StockholdersEquity-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-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:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-2227-2113-1993-1974-1961-1627-1605-1430-1513-1908-1884-1221-1181-1053-1037-954-872-952-1066-693-744-541-594-630-153
Percentage of StockholdersEquity-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-6.3-5.9-5.7-5.5-6.1-4.9-4.7-4.2-4.7-5.9-6.2-3.8-3.6-3.2-5.5-5.4-4.8-5.9-6.9-4.7-4.7-3.4-3.80.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value-538-746-626-607-616-550-506-307-365-724-650-434-398-310-314-302-230-296-191-14
Percentage of StockholdersEquity-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-1.5-2.1-1.8-1.7-1.9-1.7-1.5-0.9-1.1-2.2-2.1-1.4-1.2-0.9-1.7-1.7-1.3-1.8-1.2-0.1
Percentage of Assets us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent



Period End2019-12-312018-12-312017-12-312016-12-31
Value13-8-10-82
Percentage of StockholdersEquity0.1-0.1-0.1-0.8
Percentage of Assets0.0-0.0-0.0-0.3
Percentage of Assets us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent0.00.00.00.0

Common Stock Value

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value179213361442143912011102127015571104113014021561145214551739177115971677161816691530152116641752159515771653159914272278234323192160218021252136208320631859
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.13.74.14.03.73.33.74.63.43.54.34.84.84.65.45.48.59.48.810.49.910.010.111.110.810.310.410.19.413.413.313.613.713.112.313.513.212.111.9

Treasury Stock Value

us-gaap:TreasuryStockValue



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value333333333402139933333333333333333333333333
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.10.10.00.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value-2227-2113-1993-1974-1961-1627-1605-1430-1513-1676-1776-1908-1884-1221-1181-1053-1037-954-872-952-1066-735-660-685-693-853-720-747-715-744-539-509-541-572-610-594
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-6.3-5.9-5.7-5.5-6.1-4.9-4.7-4.2-4.7-5.2-5.4-5.9-6.2-3.8-3.6-3.2-5.5-5.4-4.8-5.9-6.9-4.8-4.0-4.3-4.7-5.6-4.2-4.2-4.2-4.7-3.2-3.0-3.4-3.6-3.6-3.8

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value461317350-47572321377183471963199531218130911813010671-6419612914753915296621671461197229104876913378
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.116.117.2-2.124.117.619.20.816.710.616.34.116.210.215.95.313.312.57.7-5.920.515.915.70.53.720.211.46.120.419.213.80.727.514.210.97.116.110.8

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value811544-93-82-755-207-75245-206
Percentage of NetCashProvidedByUsedInOperatingActivities175.9171.6-26.6174.5-132.0-64.5-19.91361.1-59.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax30.127.7-4.6-3.6-31.8-11.3-3.810.8-9.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value246178-1271582814-262316328165
Percentage of NetCashProvidedByUsedInOperatingActivities53.456.2-36.3-336.2492.0-81.683.81822.247.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.19.1-6.36.9118.6-14.316.114.47.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value116-31550938-11744838272218
Percentage of NetCashProvidedByUsedInOperatingActivities25.2-99.4145.4-80.9-205.2150.521.8400.062.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.3-16.025.11.7-49.526.54.23.210.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-913000-435-3190-333-22
Percentage of NetCashProvidedByUsedInOperatingActivities-198.00.00.0-0.0-76.0-99.40.0-1850.0-6.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-33.90.00.00.0-18.3-17.50.0-14.6-1.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value263-80-3-31-73668-44-196
Percentage of NetCashProvidedByUsedInOperatingActivities57.0-25.2-0.966.0-12.8208.1-11.7-1088.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.8-4.1-0.1-1.4-3.136.6-2.2-8.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-62-1064-130195-4298-98
Percentage of NetCashProvidedByUsedInOperatingActivities-13.4-3.218.3276.634.1-13.126.0-544.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-2.3-0.53.2-5.78.2-2.35.0-4.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-83-1383-73-75-101-87-74-79-73-107-155-82-88-25-109417-595-100-240-8-159-35-61-21-21-33-29-37-29-20-28-24-18-19-16-41144-27
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-3.1-70.3-3.6-3.3-4.3-4.8-3.8-3.5-3.5-5.8-7.9-3.5-4.6-1.4-5.618.7-61.1-11.8-26.0-0.7-16.6-4.3-6.5-1.9-2.0-4.4-3.4-3.7-3.5-2.6-3.3-2.4-2.2-2.6-2.0-4.217.5-3.7

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value69718077254-397562-68
Percentage of NetCashProvidedByUsedInInvestingActivities-83.1-5.1-109.6-102.7-251.544.8-101.4-78.593.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.63.63.93.410.7-2.13.82.7-3.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-10616730-108-2497-11-229-273-62
Percentage of NetCashProvidedByUsedInInvestingActivities127.7-12.1-41.1144.02472.312.6309.5345.684.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-3.98.51.5-4.7-105.3-0.6-11.6-12.0-3.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-43491-379171428-275262-17-95
Percentage of NetCashProvidedByUsedInInvestingActivities51.8-35.5519.2-22.7-1413.9316.1-354.121.5130.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.625.0-18.70.760.2-15.113.3-0.7-4.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-239-758800-35213318171-2441706
Percentage of NetCashProvidedByUsedInInvestingActivities288.054.8-1095.946.7-210.9-365.5-231.1308.9-2337.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-8.9-38.639.4-1.59.017.48.7-10.782.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value284-111-561-137134-179-189326
Percentage of NetCashProvidedByUsedInInvestingActivities-342.28.0768.5182.7-132.7205.7255.4-412.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.6-5.6-27.6-6.05.6-9.8-9.614.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-48-1243-4311136799-16467
Percentage of NetCashProvidedByUsedInInvestingActivities57.889.958.9-148.0-363.4-113.8221.6-84.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.8-63.2-2.14.915.55.4-8.32.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-3771148-45682-361-207-311-24-233-50-19614-116-331-200-115547-10143-39-40-128-106-4918-1040-64-69-208127-67-89-120-17-28943
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-14.058.4-22.53.6-15.2-11.3-15.8-1.1-11.2-2.7-10.00.6-6.0-18.6-10.3-5.156.2-1.215.5-3.6-4.2-15.8-11.3-4.51.7-13.80.0-7.8-9.1-24.212.6-8.0-12.1-15.0-1.7-35.15.9

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-880-6151355012450-307270
Percentage of NetCashProvidedByUsedInFinancingActivities233.4-53.6-2.96.1-138.8-118.4-0.01279.2-115.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-32.7-31.30.60.221.113.40.0-13.513.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-139-263-82-90-207302-96-138-60
Percentage of NetCashProvidedByUsedInFinancingActivities36.9-22.918.0-109.857.3-145.930.9575.025.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-5.2-13.4-4.0-3.9-8.716.5-4.9-6.1-2.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-73-176-130-55-254-209-343-57-121
Percentage of NetCashProvidedByUsedInFinancingActivities19.4-15.328.5-67.170.4101.0110.3237.551.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-2.7-9.0-6.4-2.4-10.7-11.4-17.4-2.5-5.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1152758-800352221-171577-1684
Percentage of NetCashProvidedByUsedInFinancingActivities-305.666.0175.442.7-61.5-0.555.0-2404.2722.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax42.838.6-39.41.59.40.1-8.725.4-81.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-547191564168-61-489233-130
Percentage of NetCashProvidedByUsedInFinancingActivities145.116.6-123.7204.916.9236.2-74.9541.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-20.39.727.87.3-2.6-26.811.9-5.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1101253-2119-562-576631
Percentage of NetCashProvidedByUsedInFinancingActivities-29.2109.14.623.2155.727.5-21.2-129.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.163.7-1.00.8-23.7-3.13.41.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value461317350-47572321377183471963199531218130911813010671-6419612914753915296621671461197229104876913378
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.116.117.2-2.124.117.619.20.816.710.616.34.116.210.215.95.313.312.57.7-5.920.515.915.70.53.720.211.46.120.419.213.80.727.514.210.97.116.110.8

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value811544-93-82-755-207-75245-206
Percentage of NetCashProvidedByUsedInOperatingActivities175.9171.6-26.6174.5-132.0-64.5-19.91361.1-59.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax30.127.7-4.6-3.6-31.8-11.3-3.810.8-9.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value246178-1271582814-262316328165
Percentage of NetCashProvidedByUsedInOperatingActivities53.456.2-36.3-336.2492.0-81.683.81822.247.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.19.1-6.36.9118.6-14.316.114.47.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value116-31550938-11744838272218
Percentage of NetCashProvidedByUsedInOperatingActivities25.2-99.4145.4-80.9-205.2150.521.8400.062.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.3-16.025.11.7-49.526.54.23.210.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-913000-435-3190-333-22
Percentage of NetCashProvidedByUsedInOperatingActivities-198.00.00.0-0.0-76.0-99.40.0-1850.0-6.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-33.90.00.00.0-18.3-17.50.0-14.6-1.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value263-80-3-31-73668-44-196
Percentage of NetCashProvidedByUsedInOperatingActivities57.0-25.2-0.966.0-12.8208.1-11.7-1088.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.8-4.1-0.1-1.4-3.136.6-2.2-8.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-62-1064-130195-4298-98
Percentage of NetCashProvidedByUsedInOperatingActivities-13.4-3.218.3276.634.1-13.126.0-544.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-2.3-0.53.2-5.78.2-2.35.0-4.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Net Income Loss

us-gaap:NetIncomeLoss



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value544751382873784458215245-5433344142-3272238-241177021076-74724668-27105219-8052610822525608534986489204797987
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.23.86.812.615.92.43.09.511.8-2.91.714.87.4-1.83.710.7-2.513.87.619.37.9-0.95.022.47.4-3.411.820.8-92.43.412.822.23.17.99.93.411.88.711.121.09.610.911.1

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value552841372933905063221250-35
Percentage of NetIncomeLoss101.5112.099.3102.1103.2113.6108.6102.8102.064.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.54.36.712.816.42.73.29.712.0-1.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value264951662991532378021126884
Percentage of NetIncomeLoss48.5126.7120.3104.2405.384.1137.998.1109.4-155.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.84.88.213.164.62.04.19.312.94.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value544751382873784458215245-54
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.23.86.812.615.92.43.09.511.8-2.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1591-151-371-854-2434-54-51-539-829338
Percentage of NetIncomeLoss-292.5-201.3-268.8-297.6-643.9-122.7-87.9-250.7-338.4-625.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-59.1-7.7-18.3-37.4-102.6-3.0-2.6-23.7-39.918.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4581072221332-18-5144
Percentage of NetIncomeLoss84.213.352.277.087.8-40.9-8.667.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.00.53.59.714.0-1.0-0.36.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value317-38-441180-15-87-37
Percentage of NetIncomeLoss58.3-50.7-2.914.347.6-34.1-150.0-17.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.8-1.9-0.21.87.6-0.8-4.4-1.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value551801492933834665221253-5441352148-3176245-181167221483-84825074-27107223-80126110232296089421036591211868191
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.54.17.312.816.12.53.39.712.2-2.92.115.27.7-1.73.911.0-1.813.77.819.78.7-1.05.122.88.1-3.412.021.2-92.03.413.122.93.57.910.34.212.48.911.421.710.411.211.6

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value552841372933905063221250-35
Percentage of ProfitLoss100.2105.091.9100.0101.8108.796.9100.098.864.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.54.36.712.816.42.73.29.712.0-1.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value2711001773051537398721727684
Percentage of ProfitLoss49.2125.0118.8104.1401.384.8133.898.2109.1-155.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.15.18.713.364.82.14.49.513.34.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value544751382873784458215245-54
Percentage of ProfitLoss98.793.892.698.098.795.789.297.396.8100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.23.86.812.615.92.43.09.511.8-2.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1591-151-371-854-2434-54-51-539-829338
Percentage of ProfitLoss-288.7-188.8-249.0-291.5-635.5-117.4-78.5-243.9-327.7-625.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-59.1-7.7-18.3-37.4-102.6-3.0-2.6-23.7-39.918.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4581072221332-18-5144
Percentage of ProfitLoss83.112.548.375.486.7-39.1-7.765.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.00.53.59.714.0-1.0-0.36.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value317-38-441180-15-87-37
Percentage of ProfitLoss57.5-47.5-2.714.047.0-32.6-133.8-16.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.8-1.9-0.21.87.6-0.8-4.4-1.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Depreciation Depletion And Amortization

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-83-1383-73-75-101-87-74-79-73-107-155-82-88-25-109417-595-100-240-8-159-35-61-21-21-33-29-37-29-20-28-24-18-19-16-41144-27
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-3.1-70.3-3.6-3.3-4.3-4.8-3.8-3.5-3.5-5.8-7.9-3.5-4.6-1.4-5.618.7-61.1-11.8-26.0-0.7-16.6-4.3-6.5-1.9-2.0-4.4-3.4-3.7-3.5-2.6-3.3-2.4-2.2-2.6-2.0-4.217.5-3.7

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value69718077254-397562-68
Percentage of NetCashProvidedByUsedInInvestingActivities-83.1-5.1-109.6-102.7-251.544.8-101.4-78.593.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.63.63.93.410.7-2.13.82.7-3.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-10616730-108-2497-11-229-273-62
Percentage of NetCashProvidedByUsedInInvestingActivities127.7-12.1-41.1144.02472.312.6309.5345.684.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-3.98.51.5-4.7-105.3-0.6-11.6-12.0-3.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-43491-379171428-275262-17-95
Percentage of NetCashProvidedByUsedInInvestingActivities51.8-35.5519.2-22.7-1413.9316.1-354.121.5130.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.625.0-18.70.760.2-15.113.3-0.7-4.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-239-758800-35213318171-2441706
Percentage of NetCashProvidedByUsedInInvestingActivities288.054.8-1095.946.7-210.9-365.5-231.1308.9-2337.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-8.9-38.639.4-1.59.017.48.7-10.782.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value284-111-561-137134-179-189326
Percentage of NetCashProvidedByUsedInInvestingActivities-342.28.0768.5182.7-132.7205.7255.4-412.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.6-5.6-27.6-6.05.6-9.8-9.614.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-48-1243-4311136799-16467
Percentage of NetCashProvidedByUsedInInvestingActivities57.889.958.9-148.0-363.4-113.8221.6-84.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.8-63.2-2.14.915.55.4-8.32.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Payments To Acquire Property Plant And Equipment

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-3771148-45682-361-207-311-24-233-50-19614-116-331-200-115547-10143-39-40-128-106-4918-1040-64-69-208127-67-89-120-17-28943
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-14.058.4-22.53.6-15.2-11.3-15.8-1.1-11.2-2.7-10.00.6-6.0-18.6-10.3-5.156.2-1.215.5-3.6-4.2-15.8-11.3-4.51.7-13.80.0-7.8-9.1-24.212.6-8.0-12.1-15.0-1.7-35.15.9

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-880-6151355012450-307270
Percentage of NetCashProvidedByUsedInFinancingActivities233.4-53.6-2.96.1-138.8-118.4-0.01279.2-115.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-32.7-31.30.60.221.113.40.0-13.513.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:GuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-139-263-82-90-207302-96-138-60
Percentage of NetCashProvidedByUsedInFinancingActivities36.9-22.918.0-109.857.3-145.930.9575.025.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-5.2-13.4-4.0-3.9-8.716.5-4.9-6.1-2.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-73-176-130-55-254-209-343-57-121
Percentage of NetCashProvidedByUsedInFinancingActivities19.4-15.328.5-67.170.4101.0110.3237.551.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-2.7-9.0-6.4-2.4-10.7-11.4-17.4-2.5-5.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ParentCompany srt:ReportableLegalEntities0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1152758-800352221-171577-1684
Percentage of NetCashProvidedByUsedInFinancingActivities-305.666.0175.442.7-61.5-0.555.0-2404.2722.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax42.838.6-39.41.59.40.1-8.725.4-81.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ConsolidationEliminations0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-547191564168-61-489233-130
Percentage of NetCashProvidedByUsedInFinancingActivities145.116.6-123.7204.916.9236.2-74.9541.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-20.39.727.87.3-2.6-26.811.9-5.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1101253-2119-562-576631
Percentage of NetCashProvidedByUsedInFinancingActivities-29.2109.14.623.2155.727.5-21.2-129.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.163.7-1.00.8-23.7-3.13.41.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Proceeds From Issuance Of Long Term Debt

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1708222101272221201969563640356451181715144
Percentage of RepaymentsOfLongTermDebt100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-11210127222125
Percentage of RepaymentsOfLongTermDebt-0.60.1100.0100.00.0100.0100.0100.0125.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value171234000000
Percentage of RepaymentsOfLongTermDebt100.628.50.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0587000000
Percentage of RepaymentsOfLongTermDebt0.071.40.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Payments For Repurchase Of Common Stock

us-gaap:PaymentsForRepurchaseOfCommonStock



Period End2019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-31
Value396201132269070166296156174184380036415138382350443719
Percentage of PaymentsForRepurchaseOfCommonStock100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302018-12-312018-09-302017-12-31
Value39620113270
Percentage of PaymentsForRepurchaseOfCommonStock100.0100.0100.0100.0100.0

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1708222101272221201969563640356451181715144
Percentage of RepaymentsOfLongTermDebt100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-11210127222125
Percentage of RepaymentsOfLongTermDebt-0.60.1100.0100.00.0100.0100.0100.0125.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations srt:NonGuarantorSubsidiaries0.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value171234000000
Percentage of RepaymentsOfLongTermDebt100.628.50.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations srt:ReportableLegalEntities wltw:TrinityAcquisitionPlc0.00.00.00.00.00.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0587000000
Percentage of RepaymentsOfLongTermDebt0.071.40.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.0
Percentage of LongTermDebtAndCapitalLeaseObligations srt:ReportableLegalEntities wltw:WillisNorthAmericaInc0.00.00.00.00.00.00.00.0

Debt Instrument Interest Rate Stated Percentage

Effective Income Tax Rate Continuing Operations

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

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber

us-gaap:PerformanceShares



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value0000000001110111001
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:PerformanceBasedStockOptions



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value0000012
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber95.7108.497.198.10.00.00.0

wltw:TimeBasedShares



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0000000000011111
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber100.0100.0133.375.080.083.3100.0116.7114.390.090.090.9133.3108.3158.3115.4

wltw:TimeBasedStockOptions



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value0001123
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber86.789.8107.7133.30.00.00.0

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

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

wltw:PerformanceBasedStockOptions



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value110.58110.55106.42101.9588.6589.49
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0

wltw:TimeBasedStockOptions



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value104.38101.21105.47101.11103.6299.19
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice94.491.699.199.2116.9110.8

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

Share Based Compensation

us-gaap:ShareBasedCompensation



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value2621171035111319151914292633351812161810141414127898910141391312131110
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities



Period End2019-12-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value454500678691569814164274246238322256
Percentage of DeferredTaxLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312010-09-302010-06-302009-12-31
Value885607592894299146187230330207539182
Percentage of DeferredTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Unrecognized Tax Benefits

us-gaap:UnrecognizedTaxBenefits



Period End2019-12-312018-12-312018-06-302017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value49495359562219413716131733
Percentage of UnrecognizedTaxBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Valuation Allowance

us-gaap:DeferredTaxAssetsValuationAllowance



Period End2019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value7681162134187280196221102879285
Percentage of DeferredTaxAssetsValuationAllowance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset



Period End2019-12-312019-09-302019-06-302019-03-312019-01-012018-12-31
Value96895993094610000
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.00.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-31
Value968959930946
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0

Cash And Cash Equivalents Period Increase Decrease

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents



Period End2019-12-312019-09-302018-12-312018-09-302017-12-312016-12-31
Value89587410339311030870
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302018-12-312018-09-302017-12-312016-12-31
Value0.00.00.00.01000000.00.0
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents0.00.00.00.00.10.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302018-12-312018-09-302017-12-312016-12-31
Value89587410339311027870
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.099.7100.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302018-12-312018-09-302017-12-312016-12-31
Value000020
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents0.00.00.00.00.20.0

us-gaap:AmortizationOfIntangibleAssets



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-31
Value1211181231271261271401411401411491511481571251612323161416131213141414141515
Percentage of AmortizationOfIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1000000.01000000.00.01000000.01000000.01000000.00.01000000.00.01000000.0
Percentage of AmortizationOfIntangibleAssets0.80.80.00.80.80.80.00.70.00.7

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value121118124126126128140140140143
Percentage of AmortizationOfIntangibleAssets100.0100.0100.899.2100.0100.8100.099.3100.0101.4

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1-1-10-1-2000-3
Percentage of AmortizationOfIntangibleAssets-0.8-0.8-0.80.0-0.8-1.60.00.00.0-2.1

us-gaap:MaterialReconcilingItems



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value121118123127126127140141140141149151
Percentage of AmortizationOfIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect



Period End2019-12-312018-12-31
Value1110
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect100.0100.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312018-12-31
Value1110
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect100.0100.0

us-gaap:DeferredIncomeTaxExpenseBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-28-3-13-28-45-22-22-26-229180-74-124-6414-70-28-1042112
Percentage of DeferredIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses

country:GB, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value-6-5-5-5-11-10-12-12-13-13
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value-5-4-5-5-2-3-3-3-3-3
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses83.380.0100.0100.018.230.025.025.023.123.1

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value0.0-1000000.00.0-1000000.0-1000000.00.0-1000000.00.0-1000000.00.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses-0.020.0-0.020.09.1-0.08.3-0.07.7-0.0

us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.0-1000000.00.00.01000000.0-1000000.00.00.00.00.00.00.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses-0.020.0-0.0-0.0-9.110.0-0.0-0.00.00.0-0.0-0.0

us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit

country:GB, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value-4-4-4-4-5-4-5-5-4-5
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-1000000.0-1000000.0-1000000.0-1000000.00.00.00.00.00.00.00.00.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit25.025.025.025.0-0.0-0.0-0.0-0.00.00.0-0.0-0.0

us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanContributionsByEmployer

country:GB, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-06-302018-03-31
Value231719183113
Percentage of DefinedBenefitPlanContributionsByEmployer100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-06-302018-03-31
Value29600000
Percentage of DefinedBenefitPlanContributionsByEmployer126.1352.90.00.00.00.0

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-06-302018-03-31
Value11231534
Percentage of DefinedBenefitPlanContributionsByEmployer47.811.815.883.39.730.8

us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets

country:GB, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value62596263717277787168
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value64636364686869686261
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets103.2106.8101.6101.695.894.489.687.287.389.7

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value7787887887
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets11.311.912.911.111.311.19.110.311.310.3

us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanInterestCost

country:GB, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value23232324232424242422
Percentage of DefinedBenefitPlanInterestCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value39393940353535353535
Percentage of DefinedBenefitPlanInterestCost169.6169.6169.6166.7152.2145.8145.8145.8145.8159.1

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value4554544554
Percentage of DefinedBenefitPlanInterestCost17.421.721.716.721.716.716.720.820.818.2

us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1000000.00.01000000.01000000.01000000.01000000.01000000.01000000.01000000.01000000.01000000.01000000.0
Percentage of DefinedBenefitPlanInterestCost4.30.04.34.24.34.24.24.20.00.04.24.5

us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost

country:GB, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value-33-32-35-34-29-26-21-42-31-30
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value-4-3-3-3-14-13-14-14-7-7
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost12.19.48.68.848.350.066.733.322.623.3

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value25233-123222
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost-6.1-15.6-5.7-8.8-10.346.2-14.3-4.8-6.5-6.7

us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value100012111111
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost-3.0-0.0-0.0-0.0-3.4-7.7-4.8-2.40.00.0-3.2-3.3

us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanServiceCost

country:GB, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value4334445578
Percentage of DefinedBenefitPlanServiceCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value16171616161717161716
Percentage of DefinedBenefitPlanServiceCost400.0566.7533.3400.0400.0425.0340.0320.0242.9200.0

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value5555565545
Percentage of DefinedBenefitPlanServiceCost125.0166.7166.7125.0125.0150.0100.0100.057.162.5

us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1000000.00.00.00.01000000.00.00.00.00.00.00.00.0
Percentage of DefinedBenefitPlanServiceCost25.00.00.00.025.00.00.00.00.00.00.00.0

us-gaap:RetirementPlanSponsorLocation, us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanSettlementsBenefitObligation

country:GB, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302018-12-312018-09-302018-06-30
Value8001201220
Percentage of DefinedBenefitPlanSettlementsBenefitObligation100.00.00.0100.0100.0100.0

country:US, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302018-12-312018-09-302018-06-30
Value6001100
Percentage of DefinedBenefitPlanSettlementsBenefitObligation75.00.00.09.20.00.0

wltw:OtherForeignPlans, us-gaap:PensionPlansDefinedBenefit



Period End2019-12-312019-09-302019-06-302018-12-312018-09-302018-06-30
Value21040-140
Percentage of DefinedBenefitPlanSettlementsBenefitObligation25.00.00.033.3-116.70.0

us-gaap:Depreciation



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value69585954555453511015451464645444325252322222324232121262119191817192018141615211514
Percentage of Depreciation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet

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



Period End2019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-1-2-4-6-7-110-10-20-23-14-14-8-4
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

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

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



Period End2019-12-312019-09-30
Value-2-1
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet200.050.0

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



Period End2019-12-312019-09-30
Value1000000.0-1000000.0
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet-100.050.0

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

us-gaap:DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value1666-104-12-55-318340
Percentage of DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents



Period End2019-12-312018-12-31
Value20-8
Percentage of EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312018-12-31
Value20-8
Percentage of EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0

us-gaap:FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value38-29-43-20-4-6125-24640611772171623
Percentage of FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value28-19-43-19-2-4418-1863145135610419
Percentage of FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss73.765.5100.0100.095.050.072.172.075.677.573.876.577.858.825.082.6

us-gaap:SoftwareAndSoftwareDevelopmentCosts



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-31
Value1-1-22-1-1-853581791
Percentage of FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss2.63.450.066.75.025.013.120.0-1.212.513.15.941.256.24.3

us-gaap:TrademarksAndTradeNames



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value3-3001-2-32-101222001
Percentage of FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss7.910.3-0.00.0-5.050.04.98.04.12.53.311.82.80.00.04.3

us-gaap:FinitelivedIntangibleAssetsAcquired1



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1656033603011147979-1564021
Percentage of FinitelivedIntangibleAssetsAcquired1100.0100.00.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessAcquisition, us-gaap:FiniteLivedIntangibleAssetsByMajorClass

wltw:TRANZACTAcquisition, us-gaap:CustomerRelationships



Period End2019-12-312019-07-30
Value0612
Percentage of FinitelivedIntangibleAssetsAcquired10.00.0

wltw:TRANZACTAcquisition, us-gaap:TradeSecrets



Period End2019-12-31
Value0.0
Percentage of FinitelivedIntangibleAssetsAcquired10.0

us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1622033603001111-271-782231
Percentage of FinitelivedIntangibleAssetsAcquired1100.094.80.0100.0100.00.0100.00.00.0100.0100.023.4-22.289.950.055.5

us-gaap:SoftwareAndSoftwareDevelopmentCosts



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-31
Value00000000000368-73728
Percentage of FinitelivedIntangibleAssetsAcquired10.00.00.00.00.00.00.00.00.00.00.076.610.146.818.1

us-gaap:TrademarksAndTradeNames



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value000000000000-1011003
Percentage of FinitelivedIntangibleAssetsAcquired10.00.00.00.00.00.00.00.00.00.00.00.0-11.10.0-0.624.9

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-10-3-5-8-3-82-172-922115127-5-39-1421-41
Percentage of ForeignCurrencyTransactionGainLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnSaleOfBusiness



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value-2000000-923-10000
Percentage of GainLossOnSaleOfBusiness100.00.00.00.00.00.00.0100.0100.0100.00.00.00.0

us-gaap:GoodwillForeignCurrencyTranslationGainLoss



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value66-590-9-25-11-873622516721-1211-2939
Percentage of GoodwillForeignCurrencyTranslationGainLoss100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementBusinessSegments

wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value25-243-7-9
Percentage of GoodwillForeignCurrencyTranslationGainLoss37.940.70.077.836.0

wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value31-281-6-11
Percentage of GoodwillForeignCurrencyTranslationGainLoss47.047.50.066.744.0

wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value10-7-44-5
Percentage of GoodwillForeignCurrencyTranslationGainLoss15.211.90.0-44.420.0

us-gaap:GoodwillWrittenOffRelatedToSaleOfBusinessUnit



Period End2019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0200053200050166331104
Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessUnit0.0100.00.00.00.0100.0100.00.00.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementBusinessSegments

wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302018-12-31
Value020
Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessUnit0.0100.00.0

us-gaap:ConsolidatedEntities

us-gaap:IncomeLossFromSubsidiariesNetOfTax

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value438511102702583326181201-131
Percentage of IncomeLossFromSubsidiariesNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value553821482963865368223220-45
Percentage of IncomeLossFromSubsidiariesNetOfTax126.3160.8134.5109.6149.6160.6261.5123.2109.534.4

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1592-152-372-854-1143-56-51-539-788532
Percentage of IncomeLossFromSubsidiariesNetOfTax-363.5-298.0-338.2-316.3-443.0-169.7-196.2-297.8-392.0-406.1

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value446-270221325-22-8142
Percentage of IncomeLossFromSubsidiariesNetOfTax101.8-3.963.681.9126.0-66.7-30.878.5

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value155214467174-8-35-7
Percentage of IncomeLossFromSubsidiariesNetOfTax35.441.240.024.867.4-24.2-134.6-3.9

us-gaap:IncreaseDecreaseInAccountsReceivable



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value454-275-39121264-251-1244395-205-79253121-143-38161100-105815235-106-3140128-119318012-1084913939-1266118577291-1482
Percentage of IncreaseDecreaseInAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingAssets



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value-13323812737-30122-24-4633-12115462226924118-924-5848-42541337-119177-187172182-27-20131-55-58
Percentage of IncreaseDecreaseInOtherOperatingAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value32-1194-379320-1568-393300-27836-109222-727-8123940591571614633192142-56-3574-16-52-4985203-124-735443-238
Percentage of IncreaseDecreaseInOtherOperatingLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestAndOtherIncome



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3123182625332418
Percentage of InterestAndOtherIncome100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementBusinessSegments

us-gaap:CorporateNonSegment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0111-2131
Percentage of InterestAndOtherIncome0.04.35.63.8-8.03.012.55.6

wltw:CorporateRiskAndBroking



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value16147981676
Percentage of InterestAndOtherIncome51.660.938.934.632.048.529.233.3

wltw:HumanCapitalAndBenefits



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value935610554
Percentage of InterestAndOtherIncome29.013.027.823.140.015.220.822.2

wltw:InvestmentRiskAndReinsurance



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value6551091197
Percentage of InterestAndOtherIncome19.421.727.838.536.033.337.538.9

us-gaap:LaborAndRelatedExpense



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value1340128312781348123312381275137712611145114811911127111912011196608570561567600569575570541529568502500506507490505584469462456486455449443
Percentage of LaborAndRelatedExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.00.00.00.00.01000000.00.00.00.00.0
Percentage of LaborAndRelatedExpense0.00.00.00.00.00.10.00.00.00.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1327127312591332121612211254136112831190
Percentage of LaborAndRelatedExpense99.099.298.598.898.698.698.498.8101.7103.9

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1011010102
Percentage of LaborAndRelatedExpense0.10.00.10.10.00.10.00.10.00.2

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1210181517152115
Percentage of LaborAndRelatedExpense0.90.81.41.11.41.21.61.1

us-gaap:StatementEquityComponents

us-gaap:OciBeforeReclassificationsNetOfTaxAttributableToParent

us-gaap:AccumulatedDefinedBenefitPlansAdjustment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-348131-2871235-1-65-52420-457-6-14-6-5412-22222
Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value-122-124-2316-360-36-1846615279109-53-43-138-21-9476106
Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent35.1-12400.0-766.71600.0125.4-300.0-525.7-6600.0-233.8-1580.0454.2-265.0716.7985.7350.0-783.3-345.547.7

us-gaap:AccumulatedTranslationAdjustment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value208-120-199-66-44-199582047877-74-216-36-884-12-7266-105
Percentage of OciBeforeReclassificationsNetOfTaxAttributableToParent-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:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent

us-gaap:AccumulatedDefinedBenefitPlansAdjustment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-30637-33-26421386-5353230-445312-5320-17230
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value-78-120-19-13-334-22-17583163100132-24-40-128-16-8280114
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent25.5-4000.0-271.439.4126.5-104.8-460.51383.3-307.52000.0412.5-80.0-1333.3-12800.0-800.0-410.0-470.649.6

us-gaap:AccumulatedTranslationAdjustment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value208-120-199-66-44-199582047877-74-216-36-884-12-7266-105
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent-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:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax

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



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value25-8-108-8-5-2415
Percentage of OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherCostAndExpenseOperating



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value472417412418434374406423376366391401380370373431283177179160165156173165144155156146129156192147164153153129135149163151139
Percentage of OtherCostAndExpenseOperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value28272237373452421829
Percentage of OtherCostAndExpenseOperating5.96.55.38.98.59.112.89.94.87.9

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value434384380373390332332376353330
Percentage of OtherCostAndExpenseOperating91.992.192.289.289.988.881.888.993.990.2

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0011012010
Percentage of OtherCostAndExpenseOperating0.00.00.20.20.00.30.50.00.30.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.00.00.00.01000000.00.00.00.0
Percentage of OtherCostAndExpenseOperating0.00.00.00.00.20.00.00.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1069767205
Percentage of OtherCostAndExpenseOperating2.11.42.21.71.41.94.91.2

us-gaap:OtherNoncashIncomeExpense



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-28510-4-3-2-1183654-24-9-121-160-5-16722
Percentage of OtherNoncashIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0

us-gaap:ConsolidationItems

us-gaap:OtherOperatingIncomeExpenseNet

us-gaap:MaterialReconcilingItems



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-57-74-58-70-88-62-46-104-46-39-50-95
Percentage of OtherOperatingIncomeExpenseNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromOtherInvestingActivities



Period End2019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-9013-17058-9-7-1-21-76-1627-10-17
Percentage of PaymentsForProceedsFromOtherInvestingActivities100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302018-12-312018-09-302017-12-31
Value-90135
Percentage of PaymentsForProceedsFromOtherInvestingActivities100.00.0100.0100.0100.0

us-gaap:PaymentsOfDebtIssuanceCosts



Period End2019-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-06-302013-03-312011-12-312011-09-302011-06-302011-03-31
Value0080000930014040010012005016
Percentage of PaymentsOfDebtIssuanceCosts0.00.0100.00.00.00.00.0100.0100.00.00.0100.00.0100.00.00.0100.00.00.0100.0100.00.00.0100.00.0100.0100.0

us-gaap:PaymentsOfDividendsCommonStock



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value84848477787981686872137656666670112565554535453504746474644464545444345444443
Percentage of PaymentsOfDividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value255000-1150010
Percentage of PaymentsOfDividendsCommonStock303.60.00.00.0-1.3189.90.01.50.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value258000821690022
Percentage of PaymentsOfDividendsCommonStock307.10.00.00.0105.1213.90.00.032.4

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value848484777879816868
Percentage of PaymentsOfDividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-913000-435-3190-333-22
Percentage of PaymentsOfDividendsCommonStock-1086.90.00.00.0-557.7-403.80.0-489.7-32.4

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value40000035400332
Percentage of PaymentsOfDividendsCommonStock476.20.00.00.0453.80.00.0488.2

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1212000237411330481
Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value12120002374
Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation100.0100.0100.00.00.00.0100.0100.0100.0

us-gaap:BusinessAcquisition

us-gaap:PaymentsToAcquireBusinessesGross

wltw:OtherAcquisitions



Period End2019-12-31
Value1000000.0
Percentage of PaymentsToAcquireBusinessesGross100.0

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-09-30
Value5132301280350013120-5750-46955265220819464101022511315213-4
Percentage of PaymentsToAcquireBusinessesNetOfCashAcquired100.0100.00.0100.0100.00.0100.0100.00.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value11101280350
Percentage of PaymentsToAcquireBusinessesNetOfCashAcquired20.00.80.0100.0100.00.0100.0100.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value41312000000
Percentage of PaymentsToAcquireBusinessesNetOfCashAcquired80.099.20.00.00.00.00.00.0

us-gaap:PaymentsToDevelopSoftware



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value1691717131612132320321521222418000
Percentage of PaymentsToDevelopSoftware100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value16917171316121323
Percentage of PaymentsToDevelopSoftware100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionAndOtherPostretirementBenefitsExpenseReversalOfExpenseNoncash



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-42-29-32-32-31-54-17-6115-41-34-31
Percentage of PensionAndOtherPostretirementBenefitsExpenseReversalOfExpenseNoncash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromDivestitureOfBusinessesNetOfCashDivested



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value04130000457000-1171513680135000
Percentage of ProceedsFromDivestitureOfBusinessesNetOfCashDivested0.0100.0100.00.00.00.00.0100.0100.00.00.00.0100.0100.0100.0100.0100.00.0100.0100.00.00.00.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302018-12-312018-09-302018-06-302018-03-31
Value040004
Percentage of ProceedsFromDivestitureOfBusinessesNetOfCashDivested0.0100.00.00.00.0100.0

us-gaap:ProceedsFromIssuanceOfCommonStock



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value144522243711177372019161711291149352813504319181211144231910961133
Percentage of ProceedsFromIssuanceOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value14452224371117
Percentage of ProceedsFromIssuanceOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromIssuanceOfOtherLongTermDebt



Period End2019-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value00000003232004400592000
Percentage of ProceedsFromIssuanceOfOtherLongTermDebt0.00.00.00.00.00.00.0100.0100.00.00.0100.0100.0100.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-31
Value0.0
Percentage of ProceedsFromIssuanceOfOtherLongTermDebt0.0

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-31
Value0.0
Percentage of ProceedsFromIssuanceOfOtherLongTermDebt0.0

us-gaap:ProceedsFromIssuanceOfSeniorLongTermDebt



Period End2019-12-312018-12-312018-09-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value00998-1065000060999700000
Percentage of ProceedsFromIssuanceOfSeniorLongTermDebt0.00.0100.0100.00.0100.00.00.00.0100.0100.00.00.00.00.00.0

us-gaap:ProceedsFromPaymentsToMinorityShareholders



Period End2019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-33-1-6-2-180-32-5-14-1-4-2-11-4-2-11-5-3
Percentage of ProceedsFromPaymentsToMinorityShareholders100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302018-12-312018-09-302017-12-31
Value-33-1-6-2-32
Percentage of ProceedsFromPaymentsToMinorityShareholders100.0100.0100.0100.0100.0

us-gaap:ProceedsFromRepaymentsOfLinesOfCredit



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-9065-244138-100-85113661-333922838261524-55-338492002200
Percentage of ProceedsFromRepaymentsOfLinesOfCredit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0-25-224118-88-558416
Percentage of ProceedsFromRepaymentsOfLinesOfCredit-0.0-38.591.885.588.065.630.19.8

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-9090-2020-12-2939555
Percentage of ProceedsFromRepaymentsOfLinesOfCredit100.0138.58.214.512.034.469.990.2

us-gaap:ProvisionForDoubtfulAccounts



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value-3228-203724291148132210111113242101
Percentage of ProvisionForDoubtfulAccounts100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0

us-gaap:StatementEquityComponents

us-gaap:ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent

us-gaap:AccumulatedDefinedBenefitPlansAdjustment



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value-6-2-4-2-23-9-3-7-12-10-8-10-12-9-15
Percentage of ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value-8-4-4-7-26-14-9-17-11-21-23-29-3-10
Percentage of ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent133.3200.0100.0350.0113.0155.6300.0242.991.7210.0287.5290.033.366.7

us-gaap:ReclassificationFromAociCurrentPeriodTax



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value0231-4911114-7-321-13012
Percentage of ReclassificationFromAociCurrentPeriodTax0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability



Period End2019-12-31
Value25
Percentage of RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability100.0

us-gaap:BusinessAcquisition

wltw:TRANZACTAcquisition



Period End2019-12-31
Value0.0
Percentage of RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability0.0

us-gaap:TypeOfArrangement

wltw:Modifications



Period End2019-12-31
Value5
Percentage of RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability20.0

wltw:BusinessCombinationIntegrationRelatedCostsCredits



Period End2019-12-312019-09-302018-12-312018-09-30
Value165450
Percentage of BusinessCombinationIntegrationRelatedCostsCredits100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302018-12-312018-09-30
Value1-15051
Percentage of BusinessCombinationIntegrationRelatedCostsCredits100.0-16.792.6102.0

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302018-12-312018-09-30
Value074-1
Percentage of BusinessCombinationIntegrationRelatedCostsCredits0.0116.77.4-2.0

us-gaap:ConsolidationItems

wltw:BusinessCombinationIntegrationRelatedTransactionCosts

us-gaap:MaterialReconcilingItems



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value16065450554392746340
Percentage of BusinessCombinationIntegrationRelatedTransactionCosts100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Range, us-gaap:DebtInstrument, us-gaap:VariableRate

wltw:DebtInstrumentAdditionalBasisSpreadOnVariableRate1

srt:Maximum, wltw:OneYearTermLoan, us-gaap:LondonInterbankOfferedRateLIBOR



Period End2019-12-31
Value0.0
Percentage of DebtInstrumentAdditionalBasisSpreadOnVariableRate10.0

srt:Minimum, wltw:OneYearTermLoan, us-gaap:LondonInterbankOfferedRateLIBOR



Period End2019-12-31
Value0.0
Percentage of DebtInstrumentAdditionalBasisSpreadOnVariableRate10.0

wltw:DepreciationNotIncludingIntegrationComponent



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value69585954555351493454515246454443
Percentage of DepreciationNotIncludingIntegrationComponent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1101111112
Percentage of DepreciationNotIncludingIntegrationComponent1.41.70.01.91.81.92.02.02.93.7

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value68575953545250485152
Percentage of DepreciationNotIncludingIntegrationComponent98.698.3100.098.198.298.198.098.0150.096.3

wltw:DilutiveSecuritiesEffectOnBasicEarningsPerShare



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-0.0099999999999999980.00.0-0.01-0.01-0.010.0-0.01-0.0099999999999999980.0
Percentage of DilutiveSecuritiesEffectOnBasicEarningsPerShare100.00.00.0100.0100.0100.00.0100.0100.00.0

wltw:FiniteLivedIntangibleAssetsDisposed



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value13510
Percentage of FiniteLivedIntangibleAssetsDisposed100.0100.0100.0100.00.0

us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:CustomerRelationships



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value12510
Percentage of FiniteLivedIntangibleAssetsDisposed100.066.7100.0100.00.0

us-gaap:SoftwareAndSoftwareDevelopmentCosts



Period End2019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.01000000.00.00.00.0
Percentage of FiniteLivedIntangibleAssetsDisposed0.033.30.00.00.0

wltw:FiniteLivedIntangibleAssetsReclassificationOfFavorableLeaseAgreementAssetsToRightOfUseAssets



Period End2019-12-312019-09-302019-06-302019-03-31
Value000-9
Percentage of FiniteLivedIntangibleAssetsReclassificationOfFavorableLeaseAgreementAssetsToRightOfUseAssets0.00.00.0100.0

us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:OffMarketFavorableLease



Period End2019-12-312019-09-302019-06-302019-03-31
Value000-9
Percentage of FiniteLivedIntangibleAssetsReclassificationOfFavorableLeaseAgreementAssetsToRightOfUseAssets0.00.00.0100.0

wltw:IncreaseDecreaseInFiduciaryAssets



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-977-619-5292490-459-8958671326-66
Percentage of IncreaseDecreaseInFiduciaryAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:IncreaseDecreaseInFiduciaryLiabilities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-977-619-5292490-459-8958671326-66
Percentage of IncreaseDecreaseInFiduciaryLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0

wltw:IncreaseDecreaseInProvisionForLiabilities



Period End2019-12-312018-12-31
Value-25-41
Percentage of IncreaseDecreaseInProvisionForLiabilities100.0100.0

us-gaap:ProductOrService, us-gaap:Range

wltw:IndividualRevenueStreamsPercentageOfTotalRevenue

us-gaap:ProductAndServiceOther, srt:Maximum



Period End2019-12-312019-09-302018-12-312018-09-30
Value0.00.060.00.06
Percentage of IndividualRevenueStreamsPercentageOfTotalRevenue0.0100.00.0100.0

us-gaap:ConsolidatedEntities

wltw:IntercompanyIncomeExpense

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value807459661095897928993
Percentage of IntercompanyIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-323-75-74-77-206-95-118-117-141-121
Percentage of IntercompanyIncomeExpense-403.8-101.4-125.4-116.7-189.0-163.8-121.6-127.2-158.4-130.1

us-gaap:ConsolidationItems, dei:LegalEntity

srt:ReportableLegalEntities, wltw:TrinityAcquisitionPlc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3739262331333030
Percentage of IntercompanyIncomeExpense46.252.744.134.828.456.930.932.6

srt:ReportableLegalEntities, wltw:WillisNorthAmericaInc



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value206-38-11-12664-9-5
Percentage of IntercompanyIncomeExpense257.5-51.4-18.6-18.260.66.9-9.3-5.4

wltw:PaymentsForDeferredContingentConsiderationFinancingActivities



Period End2019-12-312019-09-302018-12-312018-09-302017-12-312017-09-302017-06-302016-12-312016-09-30
Value1000922-144364
Percentage of PaymentsForDeferredContingentConsiderationFinancingActivities100.00.00.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302018-12-312018-09-302017-12-31
Value1000922
Percentage of PaymentsForDeferredContingentConsiderationFinancingActivities100.00.00.0100.0100.0

wltw:PaymentsToAcquireFixedAssetsAndSoftwareForInternalUse



Period End2019-12-312018-12-31
Value7159
Percentage of PaymentsToAcquireFixedAssetsAndSoftwareForInternalUse100.0100.0

us-gaap:ConsolidatedEntities

srt:GuarantorSubsidiaries



Period End2019-12-312018-12-31
Value31
Percentage of PaymentsToAcquireFixedAssetsAndSoftwareForInternalUse4.21.7

srt:NonGuarantorSubsidiaries



Period End2019-12-312018-12-31
Value6858
Percentage of PaymentsToAcquireFixedAssetsAndSoftwareForInternalUse95.898.3

us-gaap:ConsolidatedEntities

wltw:ProceedsFromRepaymentsOfIntercompanyInvestingActivities

srt:GuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-72-71-81-78-25538-76-63-190
Percentage of ProceedsFromRepaymentsOfIntercompanyInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:NonGuarantorSubsidiaries



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value30-238-102342397-75156195397
Percentage of ProceedsFromRepaymentsOfIntercompanyInvestingActivities-41.7335.2125.9-43.6-940.0-197.4-205.3-309.5-208.9

us-gaap:ConsolidatedEntities, us-gaap:ConsolidationItems

srt:ParentCompany, srt:ReportableLegalEntities



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value43-491379-17-1428275-2621760
Percentage of ProceedsFromRepaymentsOfIntercompanyInvestingActivities-59.7691.5-467.921.8560.0723.7344.7-27.0-31.6

us-gaap:ConsolidationItems

srt:ConsolidationEliminations



Period End2019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value239758-80035-213-318-171244-1706