<DefinitionAndReference>
  <Element Id="us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentInterestRateStatedPercentage">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfRestructuringAndRelatedCostsTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeAssetNotDesignatedAsHedgingInstrumentFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsForLegalSettlements">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ComprehensiveIncomeNoteTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RevenueOtherFinancialServices">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_TransactionFeeRevenue">
    <definition>Transaction fee revenue includes primarily consumer money transfer transaction fees which represent a per transaction fee that is based on the principal amount of the money transfer and locations from and to which funds are transferred.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CostOfServices">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockDividendsPerShareDeclared">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_EarningsPerShareAndDividendsTextBlock">
    <definition>This element may be used to capture the complete disclosure pertaining to an entity's earnings per share and cash dividends declared and paid.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementAssetsInvestmentSecurities">
    <definition>This item represents the portion of total settlement assets comprised of investment securities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_IncomeTaxExaminationTaxAndPenaltiesAccrued">
    <definition>The alleged amount of additional tax and penalties in the Notice of Deficiency related to unagreed adjustments.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RepaymentsOfCommercialPaper">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CashAndCashEquivalentsAtCarryingValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RestructuringAndRelatedCostReportableSegmentCostIncurredToDate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SpinOffRelatedTaxesLiability">
    <definition>Represents the percentage for which the Company is liable for any Spin-off Related Taxes (i) that would not have been imposed but for the existence of both an action by the Company and an action by First Data or (ii) where the Company and First Data each take actions that, standing alone, would have resulted in the imposition of such Spin-off Related Taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_OutstandingLettersOfCreditAndBankGuarantees">
    <definition>Outstanding letters of credit and bank guarantees primarily held in connection with lease arrangements and certain agent agreements.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfRestructuringReserveByTypeOfCostTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromCollectionOfNotesReceivable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_BusinessAcquisitionPurchasePriceAllocationOtherAssets">
    <definition>The amount of acquisition cost of a business combination allocated to other assets.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ReceivableForSecuritiesSoldDisclosureTextBlock">
    <definition>Represents receivable related to the requested redemption of shares in the Reserve International Liquidity Fund, Ltd.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AvailableForSaleSecuritiesChangeInNetUnrealizedHoldingGainLossNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_DerivativesPolicyGeneralTextBlock">
    <definition>Description of the entity's objectives and strategies pertaining to the use of derivative instruments and nonderivative hedging instruments in the context of the entity's overall risk management profile, and the risks associated with the use of derivatives. Indicates the purpose of derivative instruments not used for hedging purposes. Qualitative disclosures that describe the entity's objectives and strategies for holding derivatives in the context of an entity's overall risk management profile.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeAssetDesignatedAsHedgingInstrumentFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ReceivableForSecuritiesSold">
    <definition>Represents receivable related to requested redemption of shares in the Reserve International Liquidity Fund, Ltd.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_FairValueLiabilitiesMeasuredOnRecurringBasisTotal">
    <definition>Fair Value, Liabilities Measured on Recurring Basis, Total.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_VariableRateDemandNotesMaximumMaturityYear">
    <definition>Maximum maturity year for variable rate demand notes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisDerivativeFinancialInstrumentsLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_RefundableTaxDeposit">
    <definition>Refundable tax deposit relating to potential United States federal tax liabilities, including those arising from the 2003 international restructuring, which have been previously accrued in the financial statements.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_FairValueAssetsMeasuredOnRecurringBasisOtherAsset">
    <definition>This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementObligationsPayablesToAgents">
    <definition>This item represents the portion of total settlement obligations comprised of payables to agents.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RelatedPartyTransactionsDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ComprehensiveIncomeNoteTablesTextBlock">
    <definition>Comprehensive Income.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationDeferredIncomeTaxesAssetLiabilityNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ShareBasedCompensationArrangementByShareBasedPaymentAwardWeightedAverageFairValue">
    <definition>The weighted-average fair value of options granted during the period.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_RestructuringAndRelatedExpensesSellingGeneralAndAdministrative">
    <definition>Restructuring and related expenses recognized in selling, general and administrative in the income statement.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InvestmentPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IntangibleAssetsNetExcludingGoodwill">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_DefinedBenefitPlanEstimatedDiscretionaryContribution">
    <definition>The amount of discretionary contributions made by the employer.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesOther">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AvailableForSaleSecuritiesTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ReserveOnReceivable">
    <definition>Represents reserve for receivable related to requested redemption of shares in the Reserve International Liquidity Fund, Ltd.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_AmendmentFlag">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityCentralIndexKey">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueAssetsMeasuredOnRecurringBasisDerivativeFinancialInstrumentsAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromStockOptionsExercised">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedTerm">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SegmentReportingInformationProfitLoss">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeForeignCurrencyTranslationGainLossArisingDuringPeriodTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanInterestCost">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementAssetsCashAndCashEquivalents">
    <definition>This item represents the portion of total settlement assets comprised of cash and cash equivalents.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NotionalAmountOfForeignCurrencyCashFlowHedgeDerivatives">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityCurrentReportingStatus">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_NumberOfPositionsReducedFromHeadcountAssociatedWithRestructuringActivities">
    <definition>Number of positions reduced from headcount associated with restructuring activities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessCombinationDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NotionalAmountOfForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityFilerCategory">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionCostOfAcquiredEntityOtherNoncashConsideration">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Assets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Depreciation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementAssets">
    <definition>Settlement assets represent funds received or to be received from agents for unsettled money transfers, money orders and consumer payments.Settlement assets also include amounts receivable from businesses for the value of customer cross-currency payment transactions related to the global business payments segment. Settlement assets consist of cash and cash equivalents, receivables from selling agents and business-to-business customers and investment securities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_NetUnrealizedGainsLossesOnInvestmentSecurities">
    <definition>Net Unrealized Gains Losses On Investment Securities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AdditionalPaidInCapitalCommonStock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ConsolidationOfVariableInterestEntitiesPolicyTextBlock">
    <definition>Describes an entity's accounting policy regarding its principles of consolidation for variable interest entities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_BusinessAcquisitionPurchasePriceAllocationSettlementObligations">
    <definition>Settlement obligations acquired in a business combination.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ForeignCurrencyDerivativesTextBlock">
    <definition>The aggregate United States dollar notional amounts of foreign currency forward contracts as of the balance sheet date segregated by contracts designated and not designated as hedging instruments.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommitmentsAndContingencies2009">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AvailableForSaleSecuritiesAmortizedCost">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredGainLossOnDiscontinuationOfFairValueHedge">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_BusinessAcquisitionPurchasePriceAllocationOtherLiabilities">
    <definition>The amount of acquisition cost of a business combination allocated to other liabilities of the acquired entity.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SellingGeneralAndAdministrativeExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PreferredStockSharesIssued">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossBeforeReclassificationAndTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_DerivativeInstrumentsGainLossRecognizedInIncomeOnAmortizationOfHedgeAccountingAdjustments">
    <definition>The portion of the amount of net gains and losses recognized in income during the period related to the amortization of hedge accounting adjustments.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_DocumentType">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_VariableRateDemandNotesPeriodOfTimeHeld">
    <definition>This item represents the time period variable rate demand notes are typically held by the company.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeLiabilityNotDesignatedAsHedgingInstrumentFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Revenues">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueMeasurementInputsDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlansNetGainLossRecognizedInNetPeriodicBenefitCostBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_BusinessAcquisitionPurchasePriceAllocationSettlementAssets">
    <definition>Settlement Assets acquired in a business combination.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NonoperatingIncomeExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_FairValueAssetsMeasuredOnRecurringBasisStateAndMunicipalVariableRateDemandNotesAssets">
    <definition>This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsUsefulLifeMaximum">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_RestructuringAndRelatedCostRemainingExpensesExpectedToBeIncurred">
    <definition>Amount of costs expected to be incurred in future periods for the specified type of restructuring cost.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityPublicFloat">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LossContingencyAccrualAtCarryingValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LiabilitiesAndStockholdersEquity">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RestructuringReserveSettledWithCash">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockParOrStatedValuePerShare">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FiniteLivedIntangibleAssetsUsefulLifeMinimum">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Goodwill">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GainContingencyUnrecordedAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_DerivativesPolicyInterestRateHedgingTextBlock">
    <definition>Description of the entity's risk management policy for interest rate derivatives. Includes a description of the items or transactions for which risks are hedged, such as interest rate risk on fixed rate debt.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_CurrentFiscalYearEndDate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsOfDividendsCommonStock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InterestExpenseDebt">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsForSoftware">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityRegistrantName">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RestructuringAndRelatedCostExpectedCost">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ForeignCurrencyCashFlowHedgeGainLossToBeReclassifiedDuringNext12Months">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RepaymentsOfNotesPayable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_WeightedAverageEffectiveRateOnTotalBorrowings">
    <definition>Weighted average effective rate on total borrowings.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeLiabilityDesignatedAsHedgingInstrumentFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NatureOfOperations">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProfitLoss">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationCurrentAssetsCashAndCashEquivalents">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PreferredStockValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_FairValueByBalanceSheetGroupingTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_DocumentFiscalYearFocus">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_UndesignatedHedgesTextBlock">
    <definition>Schedule of the location and amount of gains and losses reported in the statement of financial performance on undesignated derivative instruments.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_DocumentPeriodEndDate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherNonoperatingIncomeExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_BusinessAndBasisOfPresentationTextBlock">
    <definition>May include a description of the formation of the entity, the nature of an entity's business, the major service it provides, the restricted net assets of the entity, basis of presentation, the use of estimates, accounting policies and new accounting guidance.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AdjustmentForAmortization">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ForeignEarnings">
    <definition>Represents amount of foreign earnings that is expected to be reinvested outside of the United States indefinitely for which no provision had been made for United States federal and state income taxes.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_RestructuringAndRelatedExpensesTotalNetOfTax">
    <definition>Total Restructuring and Related Expenses recognized in the Income Statement, Net of Tax.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_BusinessAcquisitionPurchasePriceAllocationAccountsPayableAndAccruedLiabilities">
    <definition>The amount of acquisition cost of a business combination allocated to accounts payable and accrued expenses of the acquired entity.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EarningsPerShareDiluted">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementObligations">
    <definition>Settlement obligations represent amounts payable under money transfers, money orders and consumer payment service arrangements. Settlement obligations also include amounts payable to businesses for the value of customer cross-currency payment transactions related to the global business payments segment. Settlement obligations consist of money transfer, money orders and payment service payables and payables to agents. Money transfer payables represent amounts to be paid to transferees when they request their funds. Money order payables represent amounts not yet presented for payment. Payment service payables represent amounts to be paid to businesses. Payables to agents represent amounts due to agents for money transfers that have been settled with transferees.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InvestmentIncomeInterest">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_Liabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CostsAndExpenses">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_NumberOfPositionsExpectedToBeMigratedToOtherCompanyFacilitiesAssociatedWithRestructuringActivities">
    <definition>Number of positions expected to be migrated to other company facilities associated with the restructuring activities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationAmortizableIntangibleAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PreferredStockSharesAuthorized">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_SegmentReportingDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockSharesAuthorized">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_NonCashExchangeOnDebtExchange">
    <definition>Non-cash exchange on debt exchange.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OperatingIncomeLoss">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPeriodIncreaseDecrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RestructuringAndRelatedCostReportableSegmentExpectedCost">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NetCashProvidedByUsedInOperatingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementAssetsAndObligationsDisclosureTextBlock">
    <definition>Settlement Assets and Obligations Disclosure.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_InterestInAcquiredCompanyPriorToAcquisition">
    <definition>Interest in Acquired Company, Prior to Acquisition.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionCostOfAcquiredEntityCashPaid">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InterestPaid">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EffectiveIncomeTaxRateContinuingOperations">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_AvailableForSaleSecuritiesFairValue">
    <definition>This item represents the total of all debt securities, at fair value, which are categorized neither as held-to-maturity nor trading securities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_NotionalAmountOfForeignCurrencyCashFlowHedgesNotDesignatedAsDerivativesGlobalBusinessPayments">
    <definition>Aggregate notional amount of all foreign currency derivatives not designated as hedging instruments related to Global Business Payments. Notional amount refers to the number of currency units specified in the foreign currency derivative contract.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_IncomeTaxExaminationAccruedInterest">
    <definition>The amount of estimated interest on alleged adjustments as of the balance sheet date.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_DocumentFiscalPeriodFocus">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ScheduleOfShortAndLongTermDebtTextBlock">
    <definition>This element may be used to capture a schedule containing disclosure about short and long-term debt arrangements.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanContributionsByEmployer">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementAgreementComplianceInvestment">
    <definition>Represents certain investments in compliance programs along the United States and Mexico border and to engage a monitor for that program, to be incurred over the next two to four years.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ForeignExchangeRevenues">
    <definition>Represents revenue based on the difference between the exchange rate set by the Company to the consumer and the rate at which the Company or its agents are able to acquire currency.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsForRepurchaseOfCommonStock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeTaxesPaid">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementAssetsReceivablesFromSellingAgentsAndBusinessToBusinessCustomers">
    <definition>This item represents the portion of total settlement assets comprised of receivables from selling agents and business-to-business customers.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensation">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PropertyPlantAndEquipmentNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_DerivativeWeightedAverageMaturity">
    <definition>The weighted average maturity on the group of derivatives identified.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_DebtExchangeUnamortizedPrem">
    <definition>The amount of debt premium that was originally recognized at the issuance of the instrument.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PreferredStockParOrStatedValuePerShare">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeFairValueOfDerivativeLiability">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWavgExercisePrice">
    <definition>The weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionCostOfAcquiredEntityPurchasePrice">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationLiabilitiesAssumed">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_FairValueAssetsMeasuredOnRecurringBasisTotal">
    <definition>Fair Value, Assets Measured on Recurring Basis, Total.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_FairValueAssetsMeasuredOnRecurringBasisCorporateDebtSecuritiesAsset">
    <definition>This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_PercentageOfTotalOptionsOutstanding">
    <definition>Represents First Data's percentage of total outstanding options as of period end date.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentCarryingAmount">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_DebtInstrumentUnamortizedDiscountPremNet">
    <definition>The amount of debt discount (net of debt premium) that has yet to be amortized.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_DisclosureOfAssumptionsUsedToValueStockOptionsGrantedTextBlock">
    <definition>Disclosure of assumptions used in the Black-Scholes option pricing model to determine the value of Western Union options granted.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeTaxExpenseBenefit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_UnrecognizedTaxBenefitsExcludingInterestAndPenalties">
    <definition>The gross amount of unrecognized tax benefits (tax reductions recognized in financial reports but excluded from tax returns) pertaining to uncertain tax positions taken in tax returns as of the balance sheet date.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_NotionalAmountOfInterestRateDerivativeInstruments">
    <definition>Aggregate notional amount of interest rate derivatives, which relates to the amount specified in the interest rate derivative instruments.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncomeTaxDisclosureTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_FairValueAssetsMeasuredOnRecurringBasisStateAndMunicipalDebtInstrumentsAssets">
    <definition>This element represents a certain statement of financial position asset caption which represents a class of assets, or which may include an individual asset, measured at fair value on a recurring basis.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromNotesPayable">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RelatedPartyTransactionAmountsOfTransaction">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationReclassificationAdjustmentRealizedUponSaleOrLiquidationBeforeTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeFairValueOfDerivativeAsset">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_CashFlowHedgesTextBlock">
    <definition>Schedule of the location and amount of gains and losses reported in the statement of financial performance (or when applicable, the statement of financial position, for example, gains and losses initially recognized in other comprehensive income) on derivative instruments designated and qualifying as hedging instruments in cash flow hedges.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DeferredTaxAssetsLiabilitiesNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RestructuringReservePeriodExpense">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ReceivableRedemptionRequestPerShare">
    <definition>Represents per share net asset value for the Company's shares in the Reserve International Liquidity Fund, Ltd.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementObligationsMoneyTransferMoneyOrderAndPaymentServicePayables">
    <definition>This item represents the portion of total settlement obligations comprised of money transfers, money order and payment service payables.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeForeignCurrencyTranslationReclassificationAdjustmentRealizedUponSaleOrLiquidationTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ScheduleOfRestructuringAndRelatedExpensesBySegmentTextBlock">
    <definition>Description and amount of restructuring and related expenses that are identifiable but not allocated to Western Union reporting segments, and are excluded from the measurement of segment operating profit for purposes of assessing segment performance and decision making.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_BasisOfPresentationTextBlock">
    <definition>Description of the basis of accounting used to prepare the financial statements (for example, U.S. Generally Accepted Accounting Principles, Other Comprehensive Basis of Accounting, IFRS).</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ProceedsFromReceivableForSecuritiesSold">
    <definition>Represents partial repayment of receivable related to requested redemption of shares in the Reserve International Liquidity Fund, Ltd.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtInstrumentInterestRateEffectivePercentage">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NetCashProvidedByUsedInFinancingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockSharesIssued">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ScheduleOfRestructuringAndRelatedExpensesInIncomeStatementTextBlock">
    <definition>Restructuring and related expenses reflected in the Consolidated Statements of Income.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RestructuringReserve">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CostsAssociatedWithExitOrDisposalActivitiesOrRestructuringsPolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_GrossUnrealizedLossesOnInvestmentSecurities">
    <definition>Gross Unrealized Losses on Investment Securities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DividendsCommonStockCash">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNet">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_NetCashProvidedByUsedInInvestingActivities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationAssetsAcquired">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_PaymentsToAcquireIntangibleAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_BusinessAcquisitionPurchasePriceAllocationPropertyPlantAndEquipment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CommonStockSharesOutstanding">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ForeignExchangeGainLossOnSettlementAssetsAndObligationsAndCashBalances">
    <definition>Represents foreign exchange gain/(loss) on settlement assets and obligations and cash balances.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_NotionalAmountOfForeignCurrencyForwardContract">
    <definition>Notional amount of forward contract entered into in connection with the purchase of Custom House to offset foreign exchange rate fluctuations on a Canadian dollar denominated position.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RestructuringReserveSettledWithoutCash">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_WeightedAverageExercisePriceGranted">
    <definition>Weighted Average Exercise Price Granted.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RestructuringAndRelatedCostCostIncurredToDate">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherRestrictedAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_PremiumGivenToNoteHolders">
    <definition>Premium given to note holders.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_RestructuringAndRelatedExpensesCostOfServices">
    <definition>Restructuring and related expenses recognized in cost of services in the income statement.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_BasisPoints">
    <definition>Basis Points.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityWellKnownSeasonedIssuer">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_RetainedEarningsAccumulatedDeficit">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_IncreaseDecreaseInOtherOperatingAssets">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityVoluntaryFilers">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_UseOfEstimatesTextBlock">
    <definition>Provides an entity's explanation that the preparation of financial statements in conformity with generally accepted accounting principles requires the use of management estimates.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_DebtAndCapitalLeaseObligations">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_DerivativesPolicyForeignCurrencyTextBlock">
    <definition>Description of the entity's risk management policy for foreign currency exchange rate derivatives. Includes a description of the items or transactions for which risks are hedged, such as foreign currency exchange risk on foreign currency denominated sales.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_LongTermDebtParValue">
    <definition>Including current and noncurrent par value amounts of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AccruedIncomeTaxes">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EarningsPerShareBasic">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="dei_EntityCommonStockSharesOutstanding">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_ContractualMaturitiesOfInvestmentSecuritiesTextBlock">
    <definition>This item represents the fair value summary of contractual maturities of investment securities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_GrossUnrealizedGainsOnInvestmentSecurities">
    <definition>Gross Unrealized Gains on Investment Securities.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_EarningsPerSharePolicyTextBlock">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue">
    <definition>No authoritative reference available.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
  <Element Id="wu_SettlementAssetsAndObligationsTextBlock">
    <definition>Settlement assets and obligations text block.</definition>
    <reference>No authoritative reference available.</reference>
  </Element>
</DefinitionAndReference>
