AJG


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

Table of contents



us-gaap:CommonStockValue

us-gaap:CommonStockSharesIssued
us-gaap:StatementEquityComponents

us-gaap:CommonStockSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted
us-gaap:AwardType
us-gaap:AllocatedShareBasedCompensationExpense

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:CostOfGoodsAndServicesSold

us-gaap:CostOfRevenue

us-gaap:CostsAndExpenses

us-gaap:GainLossOnInvestments

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxesPaidNet

us-gaap:InterestExpense

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:OperatingExpenses

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax
us-gaap:StatementEquityComponents
us-gaap:TradingActivityByType
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeLossNetOfTax

us-gaap:ProfitLoss
us-gaap:StatementEquityComponents

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

us-gaap:Revenues

us-gaap:Assets
us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementGeographical, us-gaap:StatementBusinessSegments
us-gaap:StatementGeographical

us-gaap:Liabilities
us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:InvestmentType, us-gaap:LineOfCreditFacility

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:StockholdersEquity

us-gaap:AssetsCurrent

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:OtherAssetsCurrent

us-gaap:MachineryAndEquipmentGross

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:FurnitureAndFixturesGross

us-gaap:LeaseholdImprovementsGross

us-gaap:ConstructionInProgressGross

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:PropertyPlantAndEquipmentNet

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

us-gaap:IntangibleAssetsNetExcludingGoodwill
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:FiniteLivedIntangibleAssetsNet
us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:DeferredTaxAssetsLiabilitiesNet

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OtherAssetsNoncurrent

us-gaap:LiabilitiesCurrent

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:LongTermDebt
us-gaap:Collateral, us-gaap:ShortTermDebtType
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:LineOfCreditFacility
us-gaap:LineOfCreditFacility
us-gaap:LineOfCreditFacility, us-gaap:ShortTermDebtType

us-gaap:LongTermDebtNoncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent

us-gaap:MinorityInterest

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:OperatingLeaseLiability

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:StockholdersEquity

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
us-gaap:StatementEquityComponents

us-gaap:CommonStockValue

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
us-gaap:StatementEquityComponents

us-gaap:MinorityInterest

us-gaap:StockIssuedDuringPeriodValueNewIssues
us-gaap:StatementEquityComponents

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss

us-gaap:ProfitLoss
us-gaap:StatementEquityComponents

us-gaap:ShareBasedCompensation

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
us-gaap:PlanName

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange
us-gaap:PlanName
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod

us-gaap:DeferredTaxLiabilities
us-gaap:BalanceSheetLocation

us-gaap:DeferredTaxAssetsNet

us-gaap:UnrecognizedTaxBenefits

us-gaap:DeferredTaxAssetsValuationAllowance

ajg:AdjustmentsToAdditionalPaidInCapitalOtherCompensationExpense
us-gaap:StatementEquityComponents

ajg:AmortizationOfDeferredCompensationAndRestrictedStock

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitments
us-gaap:GuaranteeObligationsByNature
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased
us-gaap:OtherCommitments

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFive
us-gaap:GuaranteeObligationsByNature

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFour
us-gaap:GuaranteeObligationsByNature

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearOne
us-gaap:GuaranteeObligationsByNature
us-gaap:OtherCommitments

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThereafter
us-gaap:GuaranteeObligationsByNature
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThree
us-gaap:GuaranteeObligationsByNature

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearTwo
us-gaap:GuaranteeObligationsByNature

ajg:AmountOfGainLossRecognizedEffectivenessTesting
us-gaap:DerivativeInstrumentRisk, us-gaap:IncomeStatementLocation
us-gaap:IncomeStatementLocation

ajg:BusinessAcquisitionsProFormaNetIncomeLossToControllingInterest

ajg:BusinessCombinationAggregateEarnoutObligationMaximum
us-gaap:BusinessAcquisition
ajg:BusinessCombinationAnnualizeRevenue
us-gaap:AwardType
ajg:CashAndEquityAwardWithAggregateFairValueVestedAndDistributedToParticipants
us-gaap:AwardType
ajg:CashBasedCompensationAwardExpenses

ajg:ChangeInEstimatedAcquisitionEarnoutPayables
us-gaap:AwardType
ajg:CompensationApprovedByCommitteeValue

ajg:ContractWithCustomerImpactOfChangeInForeignExchangeRates
us-gaap:StatementBusinessSegments

ajg:ContractWithCustomerLiabilityAdditions
us-gaap:StatementBusinessSegments

ajg:CostReimbursements

ajg:DeferredCompensationAndRestrictedStockExpensesBenefit
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents
ajg:DeferredCompensationAndRestrictedStockInShares
us-gaap:RetirementPlanType
ajg:DefinedBenefitPlanPercentageOfEligibleCompensationForMatchingContributionsByEmployer

ajg:EarnoutPaymentsForAcquisitions

ajg:GoodwillWrittenOffRelatedToSaleOfBusinessAndImpairment
us-gaap:StatementBusinessSegments

ajg:IncreaseDecreaseInPremiumsAndFeeReceivable

ajg:MinorityInterestIncreaseDecreaseFromRedemptions
us-gaap:StatementEquityComponents

ajg:NetBorrowingsOnPremiumFinancingDebtFacility

ajg:NetBorrowingsPaymentsOnPremiumFinancingDebtFacility

ajg:NetChangeInAccruedCompensationAndOtherAccruedLiabilities

ajg:NetChangeInCollectedBillingsAndDepositsReceivedFromCustomers
us-gaap:StatementBusinessSegments

ajg:NetProceedsFromSalesOfOperations

ajg:PaymentsOnSettlementsOfTerminatedInterestRateSwaps

ajg:PaymentsToAcquireBusinessesNetOfCashAndRestrictedCashAcquired

ajg:RecordedEarnOutPayable

ajg:RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax
us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ProductOrService

ajg:RevenueFromContractWithCustomerExcludingAssessedTaxReimbursements
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:AwardType
ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardAggregateFairValue
us-gaap:AwardType
ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodIntrinsicValue
us-gaap:TitleOfIndividual, us-gaap:PlanName
ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearOne
us-gaap:TitleOfIndividual, us-gaap:PlanName
ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearThree
us-gaap:TitleOfIndividual, us-gaap:PlanName
ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearTwo
us-gaap:AwardType
ajg:UnearnedDeferredCompensationShare
us-gaap:AwardType
ajg:UnearnedDeferredCompensationValue

ajg:WeightedAverageNumberOfCommonAndCommonEquivalentSharesOutstanding

us-gaap:AdjustmentForAmortization
us-gaap:BusinessAcquisition, us-gaap:StatementEquityComponents
us-gaap:AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts

us-gaap:BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued

us-gaap:BusinessAcquisitionProFormaEarningsPerShareBasic

us-gaap:BusinessAcquisitionProFormaEarningsPerShareDiluted
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax

us-gaap:BusinessAcquisitionsProFormaNetIncomeLoss

us-gaap:BusinessAcquisitionsProFormaRevenue
us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable
us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1

us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed

us-gaap:ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination
us-gaap:StatementBusinessSegments

us-gaap:ContractWithCustomerLiabilityRevenueRecognized
us-gaap:StatementBusinessSegments
us-gaap:RetirementPlanType
us-gaap:DefinedContributionPlanCostRecognized

us-gaap:Depreciation

us-gaap:DepreciationAmortizationAndAccretionNet

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

us-gaap:DividendsCommonStockCash
us-gaap:StatementEquityComponents

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations

us-gaap:ForeignCurrencyTransactionGainLossUnrealized
us-gaap:LongtermDebtType, us-gaap:SubsidiarySaleOfStock
us-gaap:GainLossOnDerivativeInstrumentsNetPretax

us-gaap:GoodwillAcquiredDuringPeriod
us-gaap:StatementBusinessSegments

us-gaap:GoodwillPurchaseAccountingAdjustments
us-gaap:StatementBusinessSegments

us-gaap:GoodwillTranslationAndPurchaseAccountingAdjustments
us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments
us-gaap:ImpairmentOfIntangibleAssetsFinitelived

us-gaap:IncomeTaxCreditsAndAdjustments

us-gaap:IncreaseDecreaseInAccruedIncomeTaxesPayable

us-gaap:IncreaseDecreaseInContractWithCustomerLiability

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes

us-gaap:IncreaseDecreaseInOtherOperatingAssets

us-gaap:IncreaseDecreaseInReinsurancePayables

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:InterestPaid

us-gaap:LaborAndRelatedExpense
us-gaap:ExtinguishmentOfDebt, us-gaap:LongtermDebtType, us-gaap:SubsidiarySaleOfStock
us-gaap:NotesIssued1
us-gaap:LongtermDebtType, us-gaap:SubsidiarySaleOfStock

us-gaap:OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax
us-gaap:DerivativeInstrumentRisk, us-gaap:IncomeStatementLocation

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax

us-gaap:PaymentsForCapitalImprovements

us-gaap:PaymentsForProceedsFromInvestments

us-gaap:PaymentsOfDebtIssuanceCosts

us-gaap:PaymentsToAcquireBusinessesGross

us-gaap:PaymentsToMinorityShareholders

us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromLinesOfCredit

us-gaap:RepaymentsOfLinesOfCredit
us-gaap:AwardType
us-gaap:RestrictedStockExpense
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
us-gaap:ValuationTechnique
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

us-gaap:StockGrantedDuringPeriodValueSharebasedCompensation
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesAcquisitions
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesEmployeeBenefitPlan
us-gaap:BusinessAcquisition, us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesNewIssues
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueAcquisitions
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueEmployeeBenefitPlan
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised
us-gaap:StatementEquityComponents
us-gaap:LineOfCreditFacility, us-gaap:OtherCommitments
us-gaap:SupplementaryInsuranceInformationBenefitsClaimsLossesAndSettlementExpense

ajg:AccruedCompensationAndOtherAccruedLiabilities

ajg:AccruedSupplementalDirectBillAndOtherReceivablesCurrent

ajg:BusinessAcquisitionCostOfAcquiredEntityPurchasePriceNet
us-gaap:FiniteLivedIntangibleAssetsByMajorClass, us-gaap:StatementBusinessSegments
ajg:BusinessAcquisitionPurchasePriceAllocationGoodwillNotExpectedTaxDeductibleAmount

ajg:BusinessAcquisitionsPurchasePriceAllocationGoodwillAmount

ajg:BusinessCombinationAggregateEarnoutObligationExpectedSettlementInCash

ajg:BusinessCombinationAggregateEarnoutObligationExpectedSettlementInCashOrStockAtOption

ajg:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAccruedLiability
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisition, us-gaap:StatementEquityComponents

ajg:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalentsAndRestrictedCash
us-gaap:BusinessAcquisition

ajg:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndRestrictedCash
us-gaap:BusinessAcquisition

ajg:ComputerEquipmentGross

ajg:DebtLongTermAndShortTermCombinedAmountGross
us-gaap:DebtInstrument, us-gaap:ExtinguishmentOfDebt, us-gaap:FinancialInstrument, us-gaap:LineOfCreditFacility
us-gaap:ExtinguishmentOfDebt, us-gaap:FinancialInstrument
us-gaap:ExtinguishmentOfDebt, us-gaap:LineOfCreditFacility
us-gaap:LineOfCreditFacility

ajg:DeferredTaxAssetsAccruedAndUnfundedCompensationAndEmployeeBenefits

ajg:DeferredTaxAssetsAccruedPensionLiability

ajg:DeferredTaxAssetsAlternativeMinimumTaxAndOtherCreditCarryforwards

ajg:DeferredTaxAssetsLeaseLiabilities

ajg:DeferredTaxLiabilitiesDepreciableFixedAssets

ajg:DeferredTaxLiabilitiesInvestmentRelatedPartnerships

ajg:DeferredTaxLiabilitiesOtherPrepaidItems

ajg:DeferredTaxLiabilitiesRevenueRecognition

ajg:DeferredTaxLiabilitiesRightOfUseAsset

ajg:DefinedBenefitPlanNetAmountIncludedInRetainedEarning
us-gaap:DerivativeInstrumentRisk
ajg:DerivativeContractsSettledNotionalAmount
us-gaap:DebtInstrument
ajg:EconomicDevelopmentForGrowingEconomyTaxCredit
us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
ajg:EquityMethodInvestmentAssetsOfLimitedLiabilityCompanies
us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
ajg:EquityMethodInvestmentLiabilitiesOfLimitedLiabilityCompanies

ajg:EquityMethodInvestmentSummarizedFinancialInformationFundingCommitments
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, us-gaap:InvestmentType, us-gaap:StatementEquityComponents

ajg:ExpirationLists

ajg:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFour

ajg:LandAndBuildingsGross

ajg:LiabilitiesRecordedOnSelfInsurance
us-gaap:LineOfCreditFacility

ajg:OperatingLeaseLiabilityNotYetCommenced

ajg:PremiumFinancingBorrowings

ajg:PremiumsPayableToUnderwritingEnterprises
us-gaap:Range, us-gaap:DebtInstrument
ajg:PropertyTaxCreditExpectToReceive
us-gaap:TitleOfIndividual, us-gaap:AwardType
ajg:ProvisionalCompensationCashAwardApprovedForFutureGrantByCompensationCommitteeValue
us-gaap:LongtermDebtType
ajg:RecordedUnconditionalPurchaseObligationDueAfterFourthYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
ajg:RecordedUnconditionalPurchaseObligationReceivable
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
ajg:RecordedUnconditionalPurchaseObligationReceivableAfterFifthYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
ajg:RecordedUnconditionalPurchaseObligationReceivableInFourthYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
ajg:RecordedUnconditionalPurchaseObligationReceivableInRemainderOfFiscalYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
ajg:RecordedUnconditionalPurchaseObligationReceivableInThirdYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
ajg:RecordedUnconditionalPurchaseObligationReceivableWithinOneYear

ajg:RefinedCoalProductionRelatedReceivablesCurrent

ajg:SemiAnnualPaymentsOfInterest

ajg:SemiAnnualPaymentsOfInterestNet
us-gaap:AwardType
ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionNonvestedIntrinsicValue

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPerShare

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonVestedAndExpectedToVestNumberOfShares

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedAndExpectedToVestExercisableWeightedAverageExercisePrice

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingAggregateIntrinsicValue

ajg:SharebasedCompensationArrangementNonVestedAndExpectedToVestOutstandingAggregateIntrinsicValue

us-gaap:AccountsReceivableBilledForLongTermContractsOrPrograms

us-gaap:AllowanceForDoubtfulAccountsReceivable

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents
us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssets
us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities
us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment
us-gaap:BusinessAcquisition

us-gaap:CapitalizedComputerSoftwareGross

us-gaap:CapitalizedContractCostAccumulatedAmortization

us-gaap:CapitalizedContractCostNet

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations

us-gaap:ContractWithCustomerLiability
us-gaap:StatementBusinessSegments
us-gaap:LineOfCreditFacility, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentCarryingAmount
us-gaap:CreditFacility
us-gaap:DebtInstrumentFairValue

us-gaap:DebtInstrumentUnamortizedDiscount

us-gaap:DebtLongtermAndShorttermCombinedAmount
us-gaap:LongtermDebtType, us-gaap:SubsidiarySaleOfStock
us-gaap:DebtWeightedAverageInterestRate

us-gaap:DeferredIncomeTaxAssetsNet
us-gaap:BusinessAcquisition, us-gaap:StatementBusinessSegments
us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredRevenueCurrent

us-gaap:DeferredRevenueNoncurrent

us-gaap:DeferredTaxAssetsCapitalLossCarryforwards

us-gaap:DeferredTaxAssetsGoodwillAndIntangibleAssets

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsHedgingTransactions

us-gaap:DeferredTaxAssetsInvestments

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards

us-gaap:DeferredTaxAssetsOther
us-gaap:IncomeTaxAuthority
us-gaap:DeferredTaxAssetsTaxCreditCarryforwards

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets

us-gaap:DeferredTaxLiabilitiesUndistributedForeignEarnings

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate

us-gaap:DefinedBenefitPlanBenefitObligation

us-gaap:DefinedBenefitPlanExpectedAmortizationNextFiscalYear

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanFundedStatusOfPlan

us-gaap:DefinedBenefitPlanWeightedAverageAssetAllocations
us-gaap:DefinedBenefitPlanByPlanAssetCategories

us-gaap:DerivativeAssetNotionalAmount
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeInstrumentRisk, us-gaap:FinancialInstrument, us-gaap:OptionIndexedToIssuersEquityType
us-gaap:DerivativeInstrumentsAndHedges
us-gaap:DerivativeInstrumentRisk, us-gaap:OptionIndexedToIssuersEquityType

us-gaap:DerivativeLiabilityNotionalAmount
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized

us-gaap:EquityMethodInvestments
ajg:Investment1, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, us-gaap:InvestmentType, us-gaap:StatementEquityComponents

us-gaap:EscrowDeposit
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsGross

us-gaap:FiniteLivedNoncompeteAgreementsGross

us-gaap:FiniteLivedTradeNamesGross
us-gaap:BusinessAcquisition
us-gaap:StatementBusinessSegments

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths
us-gaap:CreditFacility
us-gaap:LineOfCredit
us-gaap:CreditFacility, us-gaap:LineOfCreditFacility
us-gaap:InvestmentType, us-gaap:LineOfCreditFacility
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:LineOfCreditFacility
us-gaap:LineOfCreditFacilityFairValueOfAmountOutstanding
us-gaap:CreditFacility, us-gaap:LineOfCreditFacility
us-gaap:LineOfCreditFacilityRemainingBorrowingCapacity
us-gaap:InvestmentType, us-gaap:LineOfCreditFacility
us-gaap:LineOfCreditFacility
us-gaap:LinesOfCreditFairValueDisclosure

us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent

us-gaap:PremiumsAndOtherReceivablesNet

us-gaap:PrepaidExpenseCurrent

us-gaap:PropertyPlantAndEquipmentOther
us-gaap:LongtermDebtType
us-gaap:RecordedUnconditionalPurchaseObligation
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
us-gaap:RecordedUnconditionalPurchaseObligationDueAfterFifthYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
us-gaap:RecordedUnconditionalPurchaseObligationDueInFifthYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
us-gaap:RecordedUnconditionalPurchaseObligationDueInFourthYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
us-gaap:RecordedUnconditionalPurchaseObligationDueInRemainderOfFiscalYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
us-gaap:RecordedUnconditionalPurchaseObligationDueInSecondYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
us-gaap:RecordedUnconditionalPurchaseObligationDueInThirdYear
us-gaap:RecordedUnconditionalPurchaseObligationByCategoryOfItemPurchased
us-gaap:RecordedUnconditionalPurchaseObligationDueWithinOneYear

us-gaap:ReinsuranceRecoverables

us-gaap:RestrictedCashCurrent

us-gaap:RevenueRemainingPerformanceObligation
us-gaap:StatementBusinessSegments
us-gaap:EmployeeStockOwnershipPlanESOPDisclosuresByPlan
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate
us-gaap:EmployeeStockOwnershipPlanESOPDisclosuresByPlan
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
us-gaap:PlanName

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1

us-gaap:SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

us-gaap:ShortTermBorrowings
us-gaap:LineOfCreditFacility
us-gaap:SupplementaryInsuranceInformationOtherPolicyClaimsAndBenefitsPayable
us-gaap:Range, us-gaap:LineOfCreditFacility, us-gaap:OtherCommitments

us-gaap:UnamortizedDebtIssuanceExpense

us-gaap:UnbilledContractsReceivable

us-gaap:UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued

us-gaap:UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
us-gaap:ValuationAllowancesAndReservesType
us-gaap:ValuationAllowancesAndReservesBalance

Plots across concepts


IncomeStatement
Comprehensive Income Net Of Tax
Expenses
Income Tax Expense Benefit
Balance Sheet
Long Term Debt
Assets
Operating Lease Right Of Use Asset
Current Assets
Other Assets Current
NonCurrent Assets
Operating Lease Right Of Use Asset
PropertyPlantAndEquipmentNet
Property Plant And Equipment Net
Liabilities
Operating Lease Liability
Current Liabilities
Operating Lease Liability Current
Noncurrent Liabilities
Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent
Stockholders Equity
Accumulated Other Comprehensive Income Loss Net Of Tax
CashFlow
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInOperatingActivities
Share Based Compensation
NetCashProvidedByUsedInFinancingActivities
Proceeds From Issuance Of Long Term Debt
OperatingLeaseLiability
Operating Lease Liability Current
LesseeOperatingLeaseLiabilityPaymentsDue
Lessee Operating Lease Liability Undiscounted Excess Amount

Tables

  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:CommonStockValue █▇▇▇▇▇▇▇▇▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▅▅▅▅▃▃▃▂▂▂▂▂▂▁▁▁▁▁206.8195.9193.7192.3191.5189.6188.1186.5186.1185.3184.0183.7182.6182.1181.0180.8180.2179.5178.3177.9177.0177.1176.9176.7174.5166.7164.6161.4159.0135.1133.6131.5127.7126.8125.6124.4121.0118.3114.7112.9112.2110.3108.4NANANA
us-gaap:CommonStockSharesIssued █▇▇▇▇▇▇▇▇▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▅▅▅▅▃▃▃▂▂▂▂▂▂▁▁▁▁▁206.8195.9193.7192.3191.5189.6188.1186.5186.1185.3184.0183.7182.6182.1181.0180.8180.2179.5178.3177.9177.0177.1176.9176.7174.5166.7164.6161.4159.0135.1133.6131.5127.7126.8125.6124.4121.0118.3114.7112.9112.2110.3108.4NANANA
us-gaap:CommonStockSharesOutstanding █▇▇▇▇▇▇▇▇▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▅▅▅▅▃▃▃▂▂▂▂▂▂▁▁▁▁▁206.8195.9193.7192.3191.5189.6188.1186.5186.1185.3184.0183.7182.6182.1181.0180.8180.2179.5178.3177.9177.0177.1176.9176.7174.5166.7164.6161.4159.0135.1133.6131.5127.7126.8125.6124.4121.0118.3114.7112.9112.2110.3108.4NANANA
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic █▁201.3194.6NA191.9190.5188.7NA186.3185.8184.5NA183.3182.4181.5NA180.5179.9178.9NA177.6177.4177.0NA176.0170.6165.6NA160.2154.3134.2NA129.8127.3126.1NA123.1119.7116.4NA112.6111.0109.3NA105.5104.4NA
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount █▁1.60.4NANA1.60.3NA0.01.31.4NA1.31.70.2NA1.71.70.3NA4.56.5NANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:EarningsPerShareBasic ▄█▃▄▄█▃▃▃▇▃▃▃▆▃▃▄▂▃▃▄▁▂▃▄▁▂▃▃▂▂▃▃▂▂▂▃▁▂▂▂▁▂▂▂▂0.941.960.740.920.811.830.530.680.591.810.64000000000000010.70.631.510.57999999999999980.610.960.310.530.690.850.260.339999999999999860.760.820.130.300000000000000040.580.710.370.45000000000000020.570.730.320.270.50.60.240.360.410.380.140.510.440.420.28
us-gaap:EarningsPerShareDiluted ▄█▃▄▄▇▂▃▃▇▃▃▃▆▃▃▄▂▃▃▄▂▂▃▄▁▂▃▃▂▂▃▃▂▂▂▃▁▂▂▂▁▂▂▂▂0.921.920.720.90.791.790.510.660.581.770.62000000000000010.680.621.480.57000000000000010.610.950.310.52999999999999980.690.840.260.35000000000000010.750.810.130.300000000000000040.580.70.360.449999999999999960.570.730.320.270.50.590.240.350.410.370.140.510.440.420.28
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 EBT Margin us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,ajg:BrokerageSegment▆█▅▅▅▇▅▅▄▆▃▃▃▅▂▃▂▂▂▂▃▂▂▂▂▁1390.21610.21235.81294.61201.11435.61192.51195.91131.21381.91001.81049.41000.11195.6895.4938.7896.1878.5859.4877.6939.1825.5851.8835.5885.6751.1NANANANANANANANANANANANANANANANANANANANA
 EBT Margin us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,ajg:RiskManagementSegment▇▅▆▅▄▅▅▅▅▄▄▄▅▄▄▄▃▁█▁▁▁▁▁▂▁281.7252.7256.4244.3223.2249.5252.3246.3242.1236.4236.3236.4237.3229.9222.3224.4216.8182.6297.6176.7176.5179.3181.3179.2189.4177.2NANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 us-gaap:AllocatedShareBasedCompensationExpense us-gaap:AwardType ajg:DeferredCashParticipationPlan██▇▆▇▇▇▅▅▄▁▄▄▃▃▃▃▂▂▂▂▁▁▁▁▂▂▃▃▃2.12.01.91.61.71.71.71.21.21.10.30.91.00.80.70.70.70.40.40.40.40.30.20.30.20.40.60.70.70.8NA0.70.60.2NANANANANANANANANANANANA
 us-gaap:AllocatedShareBasedCompensationExpense us-gaap:AwardType ajg:DeferredEquityParticipationPlan█▅▆▆█▄▅▅▅▃▄▄▄▂▅▅▆▂▃▃▄▁▃▃▃3.82.73.23.03.72.32.62.62.62.02.42.42.41.92.62.63.01.82.02.12.41.42.02.12.1NANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AllocatedShareBasedCompensationExpense us-gaap:AwardType ajg:DeferredEquityParticipationPlanSubPlans██▁███▇▇█▆▆▇▇▆▆▆▆▆▆▆▆0.70.7-0.20.70.70.70.60.60.70.50.50.60.60.50.50.50.50.40.50.40.4NANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTax ▅█▇▆▇▁▅▂▃▇▂▄▂▆▃▅▅▄▂▄▃▃▂▂▅▁▁▂▄▃▄▄▃▃▃▃▃▃▂▃▃▃▃▃▃187.8497.3369.5287.9403.4-126.4260.86.629.3397.84.1105.3-31.5334.043.2273.6209.1120.2-48.3106.879.530.80.0-38.3205.0-97.7-125.4-44.3156.358.899.2105.475.918.326.584.059.639.35.430.938.919.559.556.939.9NA
us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest ▄▄▄▄▃▄▄▃▄▅▄▄▂▅▄▃▄▅▃▃▃▅▄▆▂▁█▂▁▂11.312.210.411.77.310.310.17.911.118.211.511.13.314.58.65.58.913.76.26.68.114.29.721.6-1.4-4.031.11.7-1.50.2NANANANANANANANANANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest ▅█▇▆▇▁▅▃▃▇▃▄▂▆▃▆▅▄▂▄▃▃▃▂▅▁▁▂▄▃199.1509.5379.9299.6410.7-116.1270.914.540.4416.015.6116.4-28.2348.551.8279.1218.0133.9-42.1113.487.645.09.7-16.7203.6-101.7-146.3-36.6161.067.3NANANANANANANANANANANANANANANANA
us-gaap:CostOfGoodsAndServicesSold ▃▄▂▄▁▁▃▆▄▅▆█▇▆268.8309.1216.3319.2161.2185.4280.9397.4292.0382.5434.2508.8441.8431.2NANANANANANANANANANANA309.3291.2326.2270.5171.0155.7146.976.658.137.227.729.017.719.60.711.7NA0.00.0NANA
us-gaap:CostOfRevenue ▃▄▂▄▁▁▃▆▄▅▆█▇▆268.8309.1216.3319.2161.2185.4280.9397.4292.0382.5434.2508.8441.8431.2NANANANANANANANANANANA309.3291.2326.2270.5171.0155.7146.976.658.137.227.729.017.719.60.711.7NA0.00.0NANA
us-gaap:CostsAndExpenses ██▆▇▅▆▇█▆▇▇▇▆▆▆▆▅▄▄▄▃▃▃▄▃▂▃▂▁1711.21756.61569.91639.61412.31510.91637.41710.41552.31668.81614.21688.21556.81595.41516.91516.81416.41360.41316.21387.41289.61244.71306.51349.11242.91200.41215.91191.41067.4NANANANANANANANANANANANANANANANANA
us-gaap:GainLossOnInvestments ▂▃▁▂▂▂▃▂▂█▂▂▃▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▄▂▃▂▃▂▂▂▂▂▂▂▂▁▂▂▃0.26.1-10.42.89999999999999951.3-0.113.00.31.557.20.20.65.62.0-1.7-0.91.31.41.91.50.92.2-0.43.63.5-0.1-0.2-1.73.921.0-0.55.12.99.62.50.70.00.70.10.01.3-0.1-8.02.2-1.54.8
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest ▅█▃▄▄▇▂▃▂▆▁▂▂▅▂▂▃▁▂▂▃▂▁▂▃▁▁▂222.3408.4133.7209.5171.7356.084.0114.8105.5321.843.290.3103.6242.382.176.9147.052.368.894.9137.555.728.4105.7128.530.929.595.4NANANANANANANANANANANANANANANANANANA
us-gaap:IncomeTaxExpenseBenefit █▇▅█▇▆▅▅▅▅▁▃▅▄▄▄▄▅▄▄▅▆▄▄▅▆▅▆▆▆▆▇▇▇▇▇█▇▇██▇▅██▇20.514.7-19.40000000000000221.79.90.6-21.6-22.3-15.9-29.9-84.6-48.1-20.1-43.7-31.1-41.2-33.4-15.5-32.2-35.5-18.2-2.2-39.8-35.2-19.1-1.5-25.2-5.9-1.9-3.0-10.710.93.91.811.914.619.44.46.924.324.28.3-20.224.222.013.7
us-gaap:IncomeTaxesPaidNet █▆▆▆▂▅▁▄▅▃▄▄73.741.647.40000000000000645.599999999999994-9.929.9-27.618.633.0-1.817.310.3NANA6.810.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:InterestExpense █▇▇▇▇▇▇▇▆▆▅▅▅▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▃▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁56.248.147.848.150.050.548.146.644.940.236.536.733.931.331.231.431.629.928.328.527.225.825.825.626.025.625.725.921.216.213.913.111.911.210.910.710.810.610.410.310.69.58.78.68.78.6
us-gaap:NetIncomeLoss ▄█▃▄▄▇▃▃▃▇▃▃▃▆▃▃▄▂▃▃▄▂▂▃▃▁▂▂▃▂▂▂▂▁▁▂▂▁▁▂▂▁▂▂▂▁190.2382.1142.2176.6153.7346.398.5126.1110.1334.1117.3127.6114.9273.7105.1130.4171.955.795.1122.8150.046.562.3133.3139.321.951.593.6109.049.360.074.693.540.533.561.771.728.140.546.741.715.254.746.244.029.2
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest ▅▅▅▅▃▄▃▅▅█▅▅▄▅▃▃▄▅▂▃▂▅▂▃▃▅▁▃▂▄11.611.610.911.28.19.17.111.011.317.610.510.88.812.38.17.18.512.15.97.65.711.45.97.68.310.53.27.74.78.5NANANANANANANANANANANANANANANANA
us-gaap:OperatingExpenses ▇▆▆▅▆▇██▇▇▆▆▆▆▆▅▆▅▅▅▅▅▆▅▅▅▆▅▅▄▃▃▃▃▃▂▂▂▂▂▂▁▂▁▁▁253.4233.1230.8203.2214.8257.7280.3268.0257.7262.5237.1227.7222.8216.1226.3209.0211.6200.4199.0189.6204.6204.5222.0208.1207.1203.5221.0205.0184.0157.2147.7133.1137.8133.8129.6121.6123.7108.3102.9113.9108.294.0101.284.887.481.2
us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax ▁█30.158.6NA102.4249.9-380.1NA-101.8-60.975.1-83.1-24.9-150.164.5-65.4157.433.958.4-140.1-20.6-56.7-9.9-19.4-138.7NANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedDefinedBenefitPlansAdjustment▁█0.11.0NA0.40.01.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedTranslationAdjustment▁█30.458.0NA101.9250.7-381.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ProfitLoss ▄█▃▄▄▇▂▃▃▇▃▃▃▆▃▃▄▂▂▃▃▁▂▃▃▁▁▂▃▁201.8393.7153.1187.8161.8355.4105.6137.1121.4351.7127.8138.4123.7286.0113.2118.1180.467.8101.0130.4155.757.968.2140.9147.632.454.7101.3113.757.8NANANANANANANANANANANANANANANANA
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax ▇█▆▇▆▇▆▇▆▇▆▆▆▇▆▆▅▆▅▅▅▄▅▅▅▄▄▄▄▃▃▃▂▂▂▂▂▁▂▁▁▁▁▁▁▁1933.52165.01703.61849.11584.01866.91721.41825.21657.81990.61657.41778.51660.41837.71599.01593.71489.51646.41385.01482.31427.11300.41334.91454.81371.41231.31245.41286.81179.3915.0890.2835.8779.5674.1673.2650.4649.9546.8578.4562.8546.1447.4459.1463.2459.5482.4
us-gaap:Revenues ▇█▆▇▆▇▆▇▆▇▆▆▆▇▆▆▆▅▅▅▅▄▅▅▅▄▄▄▄▃▃▃▂▂▂▂▂▁▂▁▁▁▁▁▁▁1933.52165.01703.61849.11584.01866.91721.41825.21657.81990.61657.41778.51660.41837.71599.01584.51563.41412.71385.01482.31427.11300.41334.91454.81371.41231.31245.41286.81179.3915.0890.2835.8779.5674.1673.2650.4649.9546.8578.4562.8546.1447.4459.1463.2459.5482.4
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:Assets █▇▆▆▆▆▆▆▆▅▅▅▅▅▄▄▄▃▃▃▃▃▃▃▃▃▃▃▃▂▂▂▂▁▂▁▁▁▁▁▁▁▁27817.224414.522331.421814.921306.220836.519634.819173.819200.318631.416334.016114.716230.516127.512897.412810.412569.611780.611489.611200.311384.310712.610913.810510.410716.19730.910010.09988.010019.37275.66860.55970.25562.15225.15352.35009.35133.64602.74483.54247.24581.93691.13596.0NANANA
us-gaap:Liabilities █▇▇▇▆▆▆▆▆▆▅▅▅▅▄▄▄▃▃▃▃▃▃▃▃▃▃▃▃▂▂▂▂▁▁▁▁▁▁▁▁▁▁19463.217635.016098.715996.715771.715766.414419.314261.814252.513673.211764.311502.011717.411543.08732.58638.28659.68053.37833.87459.17728.57060.37225.66802.57004.66511.36780.66732.06769.75131.44775.04038.03860.13560.43693.73373.13660.73246.13239.93027.93379.12544.02489.3NANANA
us-gaap:LiabilitiesAndStockholdersEquity █▇▆▆▆▆▆▆▆▅▅▅▅▅▄▄▄▃▃▃▃▃▃▃▃▃▃▃▃▂▂▂▂▁▂▁▁▁▁▁▁▁▁27817.224414.522331.421814.921306.220836.519634.819173.819200.318631.416334.016114.716230.516127.512897.412810.412569.611780.611489.611200.311384.310712.610913.810510.410716.19730.910010.09988.010019.37275.66860.55970.25562.15225.15352.35009.35133.64602.74483.54247.24581.93691.13596.0NANANA
us-gaap:StockholdersEquity █▆▆▆▅▅▅▅▅▅▄▄▄▄▄▄▄▃▃▄▃▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁▁8312.76731.16186.25771.75488.65029.55155.54843.34879.44880.34498.94544.54443.64514.64105.24110.03844.73662.53596.63686.53599.93597.13638.33652.43638.53145.23229.43256.03249.62144.22085.51932.21702.01664.71658.61636.21472.91356.61243.61219.31202.81147.11106.7NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:AssetsCurrent █▆▆▆▅▅▅▅▅▅▄▄▄▄▃▃▃▂▂▂▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁15939.312667.511124.211200.310760.410527.29117.59328.69547.49669.58118.78084.08365.08533.35170.65087.45107.24483.24416.14213.74485.63939.54335.84020.14261.43594.83811.23972.44440.33198.02875.62546.72602.62301.42429.52324.92631.82225.02199.42088.72416.01749.81726.0NANANA
us-gaap:CashAndCashEquivalentsAtCarryingValue █▂▂▂▁▁▂▂▂▃▂▂▂▂▂▂▂▂▂▂▁▁▂▁▁▁▁▁▃▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁3204.1526.3664.6629.9349.7352.8604.8578.9512.3871.5607.2605.0652.2697.9681.2564.9587.8564.0545.5531.8411.1425.4480.4369.7321.7276.8314.4290.5973.5739.2298.1286.9240.0224.0302.1305.2282.1301.8291.2241.4263.2333.2249.8296.3230.0227.1
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents █▃▄▄▃▂▂▂▂▂▂▂▂▁▂▂▁▁▁6375.03360.93574.33474.83002.72633.22623.92607.32546.62540.82236.82260.52344.72108.72305.02180.52068.91822.01937.6NANANA1892.5NANANA1682.0NANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsCurrent █▇█▇▆▆▇▇▇▆▇▇▆▅▅▅▅▄▄▄▄▄▅▅▅▄▅▅▃▂▂▂▂▂▁▁▁▁▁▁▁▁▁1169.5997.31113.91023.0884.2799.71074.41036.6993.2875.51024.4951.5878.1749.2708.4679.6664.1594.4633.7601.1605.2503.8709.3700.0731.4587.8666.7670.8360.2289.5261.3260.5203.9227.7179.7182.5157.9165.3188.6146.9127.0117.7126.4NANANA
us-gaap:MachineryAndEquipmentGross NANA33.0NANANA32.6NANANA30.0NANANA28.6NANANA22.5NANANA21.1NANANA23.0NANANA16.3NANANA15.1NANANA11.8NANANA11.2NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:PropertyPlantAndEquipmentGross NANA1179.6NANANA1059.3NANANA941.7NANANA880.6NANANA789.1NANANA601.6NANANA548.7NANANA445.8NANANA363.8NANANA336.5NANANA277.5NANANA
us-gaap:FurnitureAndFixturesGross NANA138.3NANANA126.0NANANA116.9NANANA112.3NANANA96.7NANANA92.7NANANA89.6NANANA78.3NANANA74.2NANANA71.2NANANA66.8NANANA
us-gaap:LeaseholdImprovementsGross NANA166.0NANANA150.2NANANA132.1NANANA124.2NANANA107.8NANANA106.1NANANA102.9NANANA77.9NANANA52.2NANANA45.9NANANA41.1NANANA
us-gaap:ConstructionInProgressGross NANA14.1NANANA18.0NANANA14.9NANANA20.1NANANA10.6NANANA46.3NANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment NANA728.9NANANA591.9NANANA504.8NANANA468.4NANANA411.5NANANA398.9NANANA353.3NANANA285.4NANANA258.4NANANA245.2NANANA201.7NANANA
us-gaap:PropertyPlantAndEquipmentNet ██████████▇▇▇▇▇▇▇▆▆▃▃▄▃▃▃▃▃▃▃▃▃▂▂▂▂▁▁▁▁▁▁▁▁454.9449.2450.7458.7461.4454.3467.4458.8458.0450.2436.9429.3427.6424.2412.2413.4387.6375.5377.6213.9213.9218.2202.7200.7198.2190.6195.4196.6193.7165.9160.4148.1123.0108.5105.4101.0100.995.791.390.587.779.475.8NANANA
us-gaap:Goodwill ██▇▇▇▇▇▆▆▆▆▅▅▅▅▅▅▅▅▅▄▄▄▄▄▄▄▄▄▃▃▂▂▂▂▂▁▁▁▁▁▁▁6630.36510.96127.05832.25756.45555.25618.55314.85241.94800.94625.64501.34403.94236.34197.94160.43989.03896.93767.83762.63716.13693.43662.93579.63569.43418.03449.63296.23027.62142.02145.21771.51506.11468.31472.71373.91285.91195.61155.31092.91072.9925.5883.7NANANA
us-gaap:IntangibleAssetsNetExcludingGoodwill NANA2399.9NA2226.02246.82318.72073.52008.81841.41773.01772.11731.01639.61644.61671.21662.61682.11627.31629.91659.81672.91698.81741.81761.51723.61776.01771.11631.51093.81078.8918.0784.7768.8809.6722.7644.9598.4561.5556.0562.4489.9483.5NANANA
 us-gaap:IntangibleAssetsNetExcludingGoodwill us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,ajg:BrokerageSegmentNANA2376.3NANANA2289.9NANANA1753.7NANANA1630.6NANANA1613.6NANANA1677.8NANANA1761.2NANANA1061.6NANANA791.6NANANANANANANANANANANA
 us-gaap:IntangibleAssetsNetExcludingGoodwill us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,ajg:RiskManagementSegmentNANA23.6NANANA28.8NANANA19.3NANANA14.0NANANA13.7NANANA21.0NANANA14.8NANANA17.2NANANA18.0NANANANANANANANANANANA
us-gaap:FiniteLivedIntangibleAssetsNet ▇█▆▁2447.32478.82399.92195.0NANA2318.7NANANANANANANANANANANANANANANANANANANANANANANANA918.0784.7768.8809.6722.7644.9598.4561.5556.0562.4NA483.5NANANA
us-gaap:DeferredTaxAssetsLiabilitiesNet NANA978.7NANANA818.2NANANA699.3NANANA573.1NANANA425.4NANANA291.4NANANA116.4NANANA155.2NANANA156.3NANANA191.6NANANA211.2NANANA
us-gaap:OperatingLeaseRightOfUseAsset ▃▅▅▁▃▅█▇▄▄358.3370.2373.9346.4362.2374.8393.5384.5368.4368.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsNoncurrent ██▇▇▇▆▇▆▆▆▅▅▅▅▅▅▅▅▄▆▅▅▄▄▄▃▃▃▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁860.8850.0769.9732.5727.7674.4773.6660.8670.1630.7573.6584.6586.7585.7567.0559.6561.3536.2504.3630.4606.6528.0492.2480.4487.6408.5385.2399.0397.3383.0320.7302.3270.6319.6283.3245.9232.4251.5235.8204.9208.8204.0181.8NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:LiabilitiesCurrent ██▇▇▇▇▆▆▆▆▅▅▅▅▃▃▃▃▃▃▃▃▃▂▃▂▂▃▃▂▂▂▂▁▂▁▂▁▁▁▂▁▁12021.311516.010135.010117.29864.09837.88921.08910.98932.58637.97693.67422.67568.67742.44912.34705.24858.04784.74611.74398.94383.74022.44191.73729.23905.43438.73642.73769.83875.03033.63284.82577.92343.72215.12362.92090.32442.02044.22073.61943.62287.11485.31577.3NANANA
us-gaap:OperatingLeaseLiabilityCurrent NANA88.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:LongTermDebt NANA19.6NANANA18.5NANANA19.9NANANA19.7NANANA26.9NANANA62.8NANANA46.1NANANA36.5NANANA32.4NANANA17.4NANANANANANANA
 us-gaap:LongTermDebt us-gaap:Collateral,us-gaap:ShortTermDebtType us-gaap:CollateralPledged,us-gaap:LetterOfCredit████▁1.01.01.01.00.9NANANANANANA1.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:FairValueByFairValueHierarchyLevel,us-gaap:LineOfCreditFacility us-gaap:FairValueInputsLevel3,ajg:NotePurchaseAgreementNANA4348.0NANANA3923.0NANANA3198.0NANANA2798.0NANANA2450.02400.02400.02125.02125.02125.02125.02125.02125.02125.02225.01525.0925.0925.0925.0725.0725.0NANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LineOfCreditFacility ajg:CollateralToClaimFundsHeldInFiduciaryCapacityByRecentAcquisitionExpiresTwoThousandTwentyOneNANA1.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LineOfCreditFacility ajg:CreditEnhancementUnderLettersOfCreditForOurCaptiveInsuranceOperationsToMeetMinimumStatutoryCapitalRequirementsExpiresAfterTwoThousandAndTwentyFiveNANA7.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LineOfCreditFacility ajg:CreditSupportUnderLettersOfCreditForDeductiblesDueByUsOnOurOwnInsuranceCoverageExpiresAfterTwoThousandAndTwentyFiveNANA9.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LineOfCreditFacility ajg:CreditSupportUnderLettersOfCreditInLieuOfSecurityDepositForAcquisitionLeaseExpiresTwoThousandAndTwentyFiveNANA0.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LineOfCreditFacility ajg:FinancialGuaranteesOfLoansToFiveCanadianBasedEmployeesTriggerNANA1.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LineOfCreditFacility,us-gaap:ShortTermDebtType ajg:RentCaptiveFacility,us-gaap:LetterOfCredit▁▁████▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅4.34.37.57.57.57.46.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.2NANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:LineOfCreditFacility,us-gaap:ShortTermDebtType ajg:SelfInsuranceDeductibles,us-gaap:LetterOfCredit▁▁▁▁▁▂▁▇███▄▄9.49.49.49.49.49.59.410.110.210.210.29.79.7NA9.712.413.112.312.312.012.011.611.811.211.210.49.79.39.89.89.8NANANANANANANANANANANANANANANA
us-gaap:LongTermDebtNoncurrent █▆▆▆▆▆▅▅▅▅▄▅▅▄▄▄▄▃▃▃▃▃▃▃▃▃▃▃▃▂▁▁▂▁▁▁▁▁▁▁▁▁▁5712.24366.34266.04265.74315.44315.13816.13815.83815.63690.33091.43141.23141.02792.12691.92741.72644.82144.72144.62044.62344.42071.82075.02125.02125.02125.02125.02125.02125.01425.0825.0825.0925.0725.0725.0725.0675.0675.0675.0675.0675.0675.0550.0NANANA
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent NANA27.8NANANA30.7NANANA33.2NANANA52.0NANANA53.5NANANA54.3NANANA54.8NANANA17.6NANANA64.6NANANA64.2NANANA20.3NANANA
us-gaap:MinorityInterest ▁▂▂▂▂▁▅▆▆█▇▆▆▆▅▅▆▆▄▄▄▄▃▄▇▇█41.348.446.546.545.940.660.068.768.477.970.868.269.569.959.762.265.364.859.254.755.955.249.955.573.074.475.7NANANANANANANANANANANANANANANANANANANA
us-gaap:OtherLiabilitiesNoncurrent ███▇▇▇▇▆▆▅▅▄▅▅▆▇▆▆▆▆▅▅▅▅▅▅▆▄▄▃▃▃▃▃▃▂▂▂▂▁▁▁▁1365.11373.61311.11255.71218.11225.91271.61127.11101.7937.1900.9862.1931.2933.71128.31191.31156.81123.91077.51015.61000.4966.1958.9948.3974.2947.61012.9837.2769.7672.8665.2635.1591.4620.3605.8557.8543.7526.9491.3409.3417.0383.7362.0NANANA
us-gaap:OperatingLeaseLiabilityNoncurrent ▂▄▅▁▃▅█▇▆302.6315.0320.9292.5307.9319.4340.9335.3327.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo NANA93.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree NANA75.1NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour NANA54.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive NANA41.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive NANA77.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:StockholdersEquity █▆▆▆▅▅▅▅▅▅▄▄▄▄▄▄▄▃▃▄▃▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁▁8312.76731.16186.25771.75488.65029.55155.54843.34879.44880.34498.94544.54443.64514.64105.24110.03844.73662.53596.63686.53599.93597.13638.33652.43638.53145.23229.43256.03249.62144.22085.51932.21702.01664.71658.61636.21472.91356.61243.61219.31202.81147.11106.7NANANA
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest █▆▅▅▄▄▄▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▁▁8354.06779.56232.75818.25534.55070.15215.54912.04947.84958.24569.74612.74513.14584.54164.94172.23910.03727.33655.83741.23655.83652.33688.23707.93711.53219.63305.1NANANA2114.8NANANA1672.8NANANANANANANANANANANA
us-gaap:CommonStockValue █▇▇▇▇▇▇▇▇▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▅▅▅▅▃▃▃▂▂▂▂▂▂▁▁▁▁▁206.8195.9193.7192.3191.5189.6188.1186.5186.1185.3184.0183.7182.6182.1181.0180.8180.2179.5178.3177.9177.0177.1176.9176.7174.5166.7164.6161.4159.0135.1133.6131.5127.7126.8125.6124.4121.0118.3114.7112.9112.2110.3108.4NANANA
us-gaap:AdditionalPaidInCapitalCommonStock █▆▆▆▆▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▄▅▅▄▄▄▄▄▃▂▂▂▂▂▂▂▂▁▁▁▁▁▁5887.34404.14264.44132.54051.03909.63825.73697.73656.53606.33541.93516.63446.43405.33388.23366.03323.53280.33265.53239.33191.23202.03209.43193.63091.92722.72649.42494.62388.01405.31358.11259.31092.01086.51055.41017.9899.3803.8693.2638.1615.6563.5507.8NANANA
us-gaap:RetainedEarningsAccumulatedDeficit ██▇▇▆▆▅▅▅▅▄▄▄▄▃▃▃▂▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁2749.12658.92371.72317.32228.32161.41901.31884.21839.31810.21558.61517.61466.01426.71095.91062.11002.9901.8916.4889.8835.2753.4774.5778.4710.8636.0676.0683.7648.4596.9596.4583.2554.9506.4510.4519.7500.7470.5482.9480.4471.3466.8488.3NANANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▅▅▄▃▂▁▄▃▃▄▃▄▄▅▅▅▄▄▄▄▄▅▅▅▆▆▆▇███▇▇▇██▇█▇████-530.5-527.8-643.6-870.4-982.2-1231.1-759.6-925.1-802.5-721.5-785.6-673.4-651.4-499.5-559.9-498.9-661.9-699.1-763.6-620.5-603.5-535.4-522.5-496.3-338.7-380.2-260.6-83.754.26.9-2.6-41.8-72.6-55.0-32.8-25.8-48.1-36.0-47.2-12.13.76.52.2NANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedDefinedBenefitPlansAdjustment▂▂▂▂▂▂▂▂▁▁▁▃▃▄▄▄▄▄▄▅▅▅▄▄▄▄▄████-55.0-55.1-56.1-54.9-55.3-55.3-56.5-57.8-58.8-59.6-61.2-48.7-49.4-43.9-43.0-43.6-44.7-46.1-47.3-38.5-39.3-42.1-42.9-42.9-43.5-43.5-44.2-24.2-24.7-25.4-25.6NANANA-52.4NANANA-49.0NANANA-18.4NANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedGainLossNetCashFlowHedgeParent▄▅▂▂▁▁▆▄▅▇▇██-72.8-39.6-96.4-112.0-121.5-119.7-28.3-63.4-38.5-17.4-5.410.27.7NA8.9NANANA-7.1NANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedOtherComprehensiveIncome▅▅▄▃▂▁▄▃▃▄▃▄▄▅▅▅▄▄▄▄▄▅▅▅▆▆▆▇███-530.5-527.8-643.6-870.4-982.2-1231.1-759.6-925.1-802.5-721.5-785.6-673.4-651.4-499.5-559.9-498.9-661.9-699.1-763.6-620.5-603.5-535.4-522.5-496.3-338.7-380.2-260.6-83.754.26.9-2.6NANANA-32.8NANANA-47.2NANANA2.2NANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedTranslationAdjustment▅▅▄▃▃▁▃▃▃▄▃▄▄▅▄▅▄▃▃▄▄▄▅▅▆▅▆▇███-402.7-433.1-491.1-703.5-805.4-1056.1-674.8-803.9-705.2-644.5-719.0-634.9-609.7-459.0-525.8-459.9-618.9-652.4-709.2-568.8-549.2-490.1-477.4-454.2-301.5-336.6-216.3-59.976.630.922.1NANANA20.5NANANA4.4NANANA20.5NANANA
us-gaap:MinorityInterest ▁▂▂▂▂▁▅▆▆█▇▆▆▆▅▅▆▆▄▄▄▄▃▄▇▇█41.348.446.546.545.940.660.068.768.477.970.868.269.569.959.762.265.364.859.254.755.955.249.955.573.074.475.7NANANANANANANANANANANANANANANANANANANA
us-gaap:StockIssuedDuringPeriodValueNewIssues 1437.9NANANANANANANANANANANANANANANANANANANANANANANANANA0.00.0NANANANANANANANANANANANANANANANANANA
us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders ▁█7.410.3NA10.36.318.9NA8.513.311.010.810.38.28.79.88.97.68.110.07.87.48.9NANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▆▅▅▇█▄▅▅▇▂▅▄▇▁▅▅402.0286.3364.9585.4693.6108.6350.1349.5515.8-96.2260.5191.3530.9-217.6261.0332.3NANANANANANANANANANANA26.4130.776.171.3204.822.651.2163.6116.4110.6-47.6101.184.6104.7-7.319.4122.886.13.5
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▃▅██▇▃▅▁▇▅▆▄▇▇▇-184.2-417.9-254.0-23.0-34.8-105.0-396.2-247.6-591.5-141.3-256.5-208.1-358.8-86.9-108.8-118.8NANANANANANANANANANANA-449.3-1416.9-44.5-421.2-265.2-132.5-32.8-227.8-72.1-70.8-11.5-44.6-42.7-192.7-27.3-42.5-24.4-27.42.6
us-gaap:NetCashProvidedByUsedInFinancingActivities █▂▂▂▁▂▂▂▂▃▂▂▂▂▂▂2782.5-118.1-123.9-128.7-400.4147.99.78.6112.7507.45.2-44.8132.169.5-1.2-165.6NANANANANANANANANANANA-255.31501.6409.5361.3104.1129.4-92.261.0-25.3-59.569.7-6.7-63.718.0118.0-23.4-32.1-55.815.1
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect █▁▂▂▂▁▁▂▁▂▁▁▂▁▂▂▂▁3014.1-213.499.5472.1369.59.316.660.75.8304.0-23.7-84.2236.0-196.3124.5111.6246.9-115.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet ▃▇▅▂▂▄▃▂▅▄▄▁▆▄▄▃▃▅▃▃▆▅▄▆▅▅▇▂█▆▃▄▄▅▄▄▄▅▄▄▃▄▃▄▄▄-17.071.420.7-26.1-34.911.7-3.5-32.427.315.29.1-52.853.312.4-0.5-6.8-9.628.0-19.3-14.050.517.3-1.940.928.921.659.3-28.486.549.8-22.03.3-0.121.03.71.00.029.012.67.7-4.011.4-21.83.60.210.8
us-gaap:NetCashProvidedByUsedInOperatingActivities ▆▅▅▇█▄▅▅▇▂▅▄▇▁▅▅402.0286.3364.9585.4693.6108.6350.1349.5515.8-96.2260.5191.3530.9-217.6261.0332.3NANANANANANANANANANANA26.4130.776.171.3204.822.651.2163.6116.4110.6-47.6101.184.6104.7-7.319.4122.886.13.5
us-gaap:NetIncomeLoss ▄█▃▄▄▇▃▃▃▇▃▃▃▆▃▃▄▂▃▃▄▂▂▃▃▁▂▂▃▂▂▂▂▁▁▂▂▁▁▂▂▁▂▂▂▁190.2382.1142.2176.6153.7346.398.5126.1110.1334.1117.3127.6114.9273.7105.1130.4171.955.795.1122.8150.046.562.3133.3139.321.951.593.6109.049.360.074.693.540.533.561.771.728.140.546.741.715.254.746.244.029.2
us-gaap:ProfitLoss ▄█▃▄▄▇▂▃▃▇▃▃▃▆▃▃▄▂▂▃▃▁▂▃▃▁▁▂▃▁201.8393.7153.1187.8161.8355.4105.6137.1121.4351.7127.8138.4123.7286.0113.2118.1180.467.8101.0130.4155.757.968.2140.9147.632.454.7101.3113.757.8NANANANANANANANANANANANANANANANA
us-gaap:ShareBasedCompensation ▅▄▄▄▄▃▄▄▄▄▄▄▂▅▄▄▄▄▄▄▄▃▃▃▃▂▃▃▃▃▂▂▂▁▂▂▂▁▃▃█▁▂▃▃▁4.4999999999999993.73.53.43.43.33.53.43.53.63.63.71.64.84.44.44.44.13.83.83.83.33.03.12.92.22.82.72.72.42.32.22.30.92.02.22.31.02.92.68.00.82.32.82.91.0
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▃▅██▇▃▅▁▇▅▆▄▇▇▇-184.2-417.9-254.0-23.0-34.8-105.0-396.2-247.6-591.5-141.3-256.5-208.1-358.8-86.9-108.8-118.8NANANANANANANANANANANA-449.3-1416.9-44.5-421.2-265.2-132.5-32.8-227.8-72.1-70.8-11.5-44.6-42.7-192.7-27.3-42.5-24.4-27.42.6
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities █▂▂▂▁▂▂▂▂▃▂▂▂▂▂▂2782.5-118.1-123.9-128.7-400.4147.99.78.6112.7507.45.2-44.8132.169.5-1.2-165.6NANANANANANANANANANANA-255.31501.6409.5361.3104.1129.4-92.261.0-25.3-59.569.7-6.7-63.718.0118.0-23.4-32.1-55.815.1
us-gaap:ProceedsFromIssuanceOfLongTermDebt █▁▁▁▁▄▁▁▂▄▁▁1561.525.0-49.7-50.2-50.2575.00.00.0125.0600.0-50.00.0NANA300.098.0NANA100.00.0NANANANANANA0.0-100.0700.0600.00.00.0NANA0.0NANANA0.0NANANANANANANA
us-gaap:PaymentsOfDividendsCommonStock █▇▆▆▆▆▆▆▆▆▅▅▅▅▅▅▅▅▄▄▄▄▄▄▄▄▄▃▃▃▂▂▂▂▆▂▂▂▁▁▁▁▁▁▁▁105.097.487.2999999999999786.6000000000000286.187.481.380.180.179.675.675.374.876.171.170.070.271.467.967.967.568.965.067.262.662.758.858.256.849.346.645.945.944.284.741.139.838.837.237.036.934.733.833.833.132.8
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value206195193192191189188186186185184183182182181180180179178177177177176176174166164161159135133131127126125124121118114112112110108102
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.80.90.90.90.91.01.01.01.01.11.11.11.11.41.41.41.51.61.61.61.71.61.71.61.71.61.61.61.91.92.22.32.42.32.52.42.62.62.72.43.03.03.2

Common Stock Shares Issued

us-gaap:CommonStockSharesIssued

us-gaap:CommonStockSharesIssued


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value206195193192191189188186186185184183182182181180180179178177177177176176174166164161159135133131127126125124121118114112112110108102
Percentage of CommonStockSharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStockSharesIssued us-gaap:StatementEquityComponents

us-gaap:CommonStock


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value206195193192191189188186186185184181
Percentage of CommonStockSharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Outstanding

us-gaap:CommonStockSharesOutstanding

us-gaap:CommonStockSharesOutstanding


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value206195193192191189188186186185184183182182181180180179178177177177176176174166164161159135133131127126125124121118114112112110108102
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value201194191190188186185184183182181180179178177177177176170165160154134129127126123119116112111109105104
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount


Antidilutive
Period End2021-06-302021-03-312020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value1600000.0400000.01600000.0300000.001300000.01400000.01300000.01700000.0200000.01700000.01700000.0300000.04500000.06500000.0
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.941.960.740.920.811.830.530.680.591.810.640.70.631.510.580.610.960.310.530.690.850.260.340.760.820.130.30.580.710.370.450.570.730.320.270.50.60.240.360.410.380.140.510.440.420.28
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareDiluted


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.921.920.720.90.791.790.510.660.581.770.620.680.621.480.570.610.950.310.530.690.840.260.350.750.810.130.30.580.70.360.450.570.730.320.270.50.590.240.350.410.370.140.510.440.420.28
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Allocated Share Based Compensation Expense

us-gaap:AllocatedShareBasedCompensationExpense us-gaap:AwardType

us-gaap:AllocatedShareBasedCompensationExpense

ajg:DeferredCashParticipationPlan


Allocated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value2.12.01.91.61.71.71.71.21.21.10.30.91.00.80.70.70.70.40.40.40.40.30.20.30.20.40.60.70.70.80.70.60.2
Percentage of AllocatedShareBasedCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.10.10.10.10.00.10.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.10.10.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:DeferredCashParticipationPlan0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

ajg:DeferredEquityParticipationPlan


Allocated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-30
Value3.82.73.23.03.72.32.62.62.62.02.42.42.41.92.62.63.01.82.02.12.41.42.02.12.1
Percentage of AllocatedShareBasedCompensationExpense181.0135.0168.4187.5217.6135.3152.9216.7216.7181.8800.0266.7240.0237.5371.4371.4428.6450.0500.0525.0600.0466.71000.0700.01050.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.20.20.20.10.20.10.20.10.10.10.10.10.20.20.20.10.10.10.20.10.10.10.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:DeferredEquityParticipationPlan0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

ajg:DeferredEquityParticipationPlanSubPlans


Allocated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.70.7-0.20.70.70.70.60.60.70.50.50.60.60.50.50.50.50.40.50.40.4
Percentage of AllocatedShareBasedCompensationExpense33.335.0-10.543.841.241.235.350.058.345.5166.766.760.062.571.471.471.4100.0125.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.0-0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:DeferredEquityParticipationPlanSubPlans0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value187497369287403-126.42606.6293974.1105-31.533443273209120-48.310679300.0-38.3205-97.7-125.4-44.315658991057518268459395.4303819595639
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.723.021.715.625.5-6.815.20.41.820.00.25.9-1.918.22.717.214.07.3-3.57.25.62.40.0-2.614.9-7.9-10.1-3.413.36.411.112.69.72.73.912.99.27.20.95.57.14.413.012.38.7

Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value111210117.310107.9111811113.3148.65.58.9136.26.68.1149.721-1.4-4.0311.7-1.50.2
Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.60.60.60.50.60.60.40.70.90.70.60.20.80.50.30.60.80.40.40.61.10.71.5-0.1-0.32.50.1-0.10.0

Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value199509379299410-116.1270144041615116-28.234851279218133-42.111387459.7-16.7203-101.7-146.3-36.616167
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.323.522.316.225.9-6.215.70.82.420.90.96.5-1.719.03.217.514.68.1-3.07.76.13.50.7-1.114.8-8.3-11.7-2.813.77.4

Cost Of Goods And Services Sold

us-gaap:CostOfGoodsAndServicesSold

us-gaap:CostOfGoodsAndServicesSold


Cost
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312010-09-30
Value268309216319161185280397292382434508441431309291326270171155146765837272917190.7110.00.0
Percentage of CostOfGoodsAndServicesSold100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.914.312.717.310.29.916.321.817.619.226.228.626.623.525.123.425.322.918.717.517.69.88.65.54.34.53.23.40.12.10.00.0

Cost Of Revenue

us-gaap:CostOfRevenue

us-gaap:CostOfRevenue


Cost
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312010-09-30
Value268309216319161185280397292382434508441431309291326270171155146765837272917190.7110.00.0
Percentage of CostOfRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.914.312.717.310.29.916.321.817.619.226.228.626.623.525.123.425.322.918.717.517.69.88.65.54.34.53.23.40.12.10.00.0

Costs And Expenses

us-gaap:CostsAndExpenses

us-gaap:CostsAndExpenses


Costs
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30
Value17111756156916391412151016371710155216681614168815561595151615161416136013161387128912441306134912421200121511911067
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax88.581.192.288.789.280.995.193.793.683.897.494.993.886.894.995.295.182.695.093.690.495.797.992.790.697.597.692.690.5

Gain Loss On Investments

us-gaap:GainLossOnInvestments

us-gaap:GainLossOnInvestments


Gain
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.26.1-10.42.89999999999999951.3-0.1130.31.5570.20.65.62.0-1.7-0.91.31.41.91.50.92.2-0.43.63.5-0.1-0.2-1.73.921-0.55.12.99.62.50.70.00.70.10.01.3-0.1-8.02.2-1.54.8
Percentage of GainLossOnInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.3-0.60.20.1-0.00.80.00.12.90.00.00.30.1-0.1-0.10.10.10.10.10.10.2-0.00.20.3-0.0-0.0-0.10.32.3-0.10.60.41.40.40.10.00.10.00.00.2-0.0-1.70.5-0.31.0

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

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value22240813320917135684114105321439010324282761475268941375528105128302995
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.518.97.811.310.819.14.96.36.416.22.65.16.213.25.14.89.93.25.06.49.64.32.17.39.42.52.47.4

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, ajg:BrokerageSegment


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value2994802072762474101511991824121111631703181541412121171231491781007312215661
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest134.8117.6155.0131.9144.3115.4180.8174.1172.8128.2258.1180.7164.7131.6188.4183.6144.6225.0180.1157.1129.6179.5258.1115.9121.9197.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax15.522.212.214.915.622.08.811.011.020.76.79.210.317.49.78.914.37.18.910.112.57.75.58.411.45.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:BrokerageSegment21.629.80.021.420.628.60.016.716.129.80.015.617.126.70.015.023.713.40.017.019.012.10.014.717.78.1

us-gaap:OperatingSegments, ajg:RiskManagementSegment


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value3324252513252321212227222421232622222421222419222623
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest15.05.918.912.17.77.228.218.919.96.864.424.723.28.928.434.515.643.835.822.716.343.169.021.220.876.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.71.11.51.40.81.41.41.21.31.11.71.31.41.21.51.71.51.41.81.51.61.81.51.51.91.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:RiskManagementSegment11.99.50.010.45.910.30.08.88.79.30.09.410.19.40.011.810.612.50.012.212.713.40.012.514.113.3

us-gaap:OperatingSegments, us-gaap:Corporate


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-110.8-96.0-98.90000000000003-92.2-89.3-80.4-91.6-106.8-97.8-112.6-96.1-95.2-91.0-98.2-95.9-90.8-88.4-88.3-79.7-75.7-63.1-68.3-64.5-39.2-54.8-53.7
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest-49.8-23.5-74.0-44.0-52.0-22.6-109.0-93.0-92.7-35.0-222.5-105.4-87.8-40.5-116.8-118.1-60.1-168.8-115.8-79.8-45.9-122.6-227.1-37.1-42.6-173.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-5.7-4.4-5.8-5.0-5.6-4.3-5.3-5.9-5.9-5.7-5.8-5.4-5.5-5.3-6.0-5.7-5.9-5.4-5.8-5.1-4.4-5.3-4.8-2.7-4.0-4.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Corporate-42.4-31.80.0-29.7-55.9-44.20.0-27.9-34.4-30.20.0-19.3-21.5-23.80.0-21.1-23.5-25.10.0-17.7-20.3-23.10.0-8.9-18.5-17.7

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxExpenseBenefit


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2014-19.400000000000002219.90.6-21.6-22.3-15.9-29.9-84.6-48.1-20.1-43.7-31.1-41.2-33.4-15.5-32.2-35.5-18.2-2.2-39.8-35.2-19.1-1.5-25.2-5.9-1.9-3.0-10.7103.91.81114194.46.924248.3-20.2242213
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.10.7-1.11.20.60.0-1.3-1.2-1.0-1.5-5.1-2.7-1.2-2.4-1.9-2.6-2.2-0.9-2.3-2.4-1.3-0.2-3.0-2.4-1.4-0.1-2.0-0.5-0.2-0.3-1.21.30.50.31.82.23.00.81.24.34.41.9-4.45.24.82.8

Income Taxes Paid Net

us-gaap:IncomeTaxesPaidNet

us-gaap:IncomeTaxesPaidNet


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312017-09-30
Value73414745-9.929-27.61833-1.817106.810
Percentage of IncomeTaxesPaidNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.81.92.82.5-0.61.6-1.61.02.0-0.11.00.60.40.6

Interest Expense

us-gaap:InterestExpense

us-gaap:InterestExpense


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value56484748505048464440363633313131312928282725252526252525211613131111101010101010109.58.78.68.78.6
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.92.22.82.63.22.72.82.62.72.02.22.12.01.72.02.02.11.82.01.91.92.01.91.81.92.12.12.01.81.81.61.61.51.71.61.61.71.91.81.81.92.11.91.91.91.8

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value19038214217615334698126110334117127114273105130171559512215046621331392151931094960749340336171284046411554464429
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.817.68.39.69.718.55.76.96.616.87.17.26.914.96.68.211.53.46.98.310.53.64.79.210.21.84.17.39.25.46.78.912.06.05.09.511.05.17.08.37.63.411.910.09.66.1

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value111110118.19.17.111111710108.8128.17.18.5125.97.65.7115.97.68.3103.27.74.78.5
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.50.60.60.50.50.40.60.70.90.60.60.50.70.50.40.60.70.40.50.40.90.40.50.60.90.30.60.40.9

Operating Expenses

us-gaap:OperatingExpenses

us-gaap:OperatingExpenses


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value25323323020321425728026825726223722722221622620921120019918920420422220820720322120518415714713313713312912112310810211310894101848781
Percentage of OperatingExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.110.813.511.013.613.816.314.715.513.214.312.813.411.814.213.114.212.214.412.814.315.716.614.315.116.517.715.915.617.216.615.917.719.819.318.719.019.817.820.219.821.022.018.319.016.8

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

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value3058102249-380.1-101.8-60.975-83.1-24.9-150.164-65.41573358-140.1-20.6-56.7-9.9-19.4-138.7
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.62.75.515.8-20.4-5.6-3.73.8-5.0-1.4-9.03.5-4.19.92.33.5-10.1-1.4-4.0-0.8-1.5-9.5

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value3058101250-381.3-98.7-60.774-84.1-25.2-144.662-65.91593356-140.4-19.6-59.1-12.7-23.2-152.7
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax101.099.099.5100.3100.397.099.799.2101.2101.296.396.6100.8101.098.897.3100.295.1104.2128.3119.6110.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.62.75.515.8-20.4-5.4-3.73.7-5.1-1.4-8.73.4-4.110.02.23.4-10.1-1.3-4.1-1.0-1.7-10.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NoncontrollingInterest


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value-0.30.60.5-0.81.2-3.1-0.20.61.00.3-5.5-2.20.5-1.60.41.60.3-1.02.42.83.814
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax-1.01.00.5-0.3-0.33.00.30.8-1.2-1.23.7-3.4-0.8-1.01.22.7-0.24.9-4.2-28.3-19.6-10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.00.00.0-0.10.1-0.2-0.00.00.10.0-0.3-0.10.0-0.10.00.10.0-0.10.20.20.31.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax us-gaap:TradingActivityByType

us-gaap:ForeignExchange


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1.2-2.10.40.10.3-0.10.00.20.1
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax2.00.00.40.0-0.10.0-0.0-0.30.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.10.00.00.0-0.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ForeignExchange0.00.00.00.00.00.00.00.00.0

Other Comprehensive Income Loss Net Of Tax

us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-31
Value0.11.00.40.01.2
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.00.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.0

us-gaap:AccumulatedGainLossNetCashFlowHedgeParent


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-31
Value-33.2569.5-1.8-91.4
Percentage of OtherComprehensiveIncomeLossNetOfTax-33200.05680.02375.00.0-7616.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.72.60.5-0.1-4.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AccumulatedGainLossNetCashFlowHedgeParent0.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-31
Value-2.7115111248-471.5
Percentage of OtherComprehensiveIncomeLossNetOfTax-2700.011580.027950.00.0-39291.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.15.36.015.7-25.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-31
Value3058101250-381.3
Percentage of OtherComprehensiveIncomeLossNetOfTax30400.05800.025475.00.0-31775.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.62.75.515.8-20.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value201393153187161355105137121351127138123286113118180671011301555768140147325410111357
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.418.29.010.210.219.06.17.57.317.77.77.87.515.67.17.412.14.17.38.810.94.55.19.710.82.64.47.99.66.3

us-gaap:ProfitLoss us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Profit
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1111118.19.111111710108.8128.17.48.5125.97.65.7115.97.68.310
Percentage of ProfitLoss5.72.96.05.02.68.09.35.08.27.87.14.37.26.34.717.85.85.83.719.78.75.45.632.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.50.60.50.50.60.70.90.60.60.50.70.50.50.60.70.40.50.40.90.40.50.60.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Profit
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1903821761533461261103341171271142731051301715595122150466213313921
Percentage of ProfitLoss94.397.194.095.097.492.090.795.091.892.292.995.792.8110.495.382.294.294.296.380.391.394.694.467.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.817.69.69.718.56.96.616.87.17.26.914.96.68.211.53.46.98.310.53.64.79.210.21.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Revenue From Contract With Customer Excluding Assessed Tax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value19332165170318491584186617211825165719901657177816601837159915931489164613851482142713001334145413711231124512861179915890835779674673650649546578562546447459463459482
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:OperatingSegments, ajg:BrokerFees, ajg:BrokerageSegment


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value293269295277278256261231253220253195225205
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax15.917.015.816.115.315.413.213.914.313.313.812.214.213.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax15.917.015.816.115.315.413.213.914.313.313.812.214.213.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:BrokerFees ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, ajg:BrokerFees, ajg:RiskManagementSegment


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value202190211214211208202202199201194188190181
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.012.011.312.411.612.610.212.211.212.210.611.812.012.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax11.012.011.312.411.612.610.212.211.212.210.611.812.012.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:BrokerFees ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, ajg:Commissions, ajg:BrokerageSegment


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value8898271017792809777940685707688839624637618
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax48.152.254.546.044.446.947.241.439.841.445.739.040.041.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax48.152.254.546.044.446.947.241.439.841.445.739.040.041.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:Commissions ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, ajg:ContingentRevenue, ajg:BrokerageSegment


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value3437452730294815252134212121
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.92.42.41.61.71.82.40.91.41.31.91.31.41.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.92.42.41.61.71.82.40.91.41.31.91.31.41.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:ContingentRevenue ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, ajg:NetGainsOnDivestitures, ajg:BrokerageSegment


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3.41.00.2133.31.9570.60.66.12.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.00.80.20.12.90.00.00.40.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.00.80.20.12.90.00.00.40.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:NetGainsOnDivestitures ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, ajg:Reimbursements, ajg:RiskManagementSegment


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value4132373734333334373534333335
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.22.02.02.21.92.01.72.12.12.11.92.12.12.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.22.02.02.21.92.01.72.12.12.11.92.12.12.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:Reimbursements ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, ajg:SupplementalRevenueMember, ajg:BrokerageSegment


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value5450595749465645434852383635
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.03.23.23.32.72.82.82.82.52.92.82.42.32.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.03.23.23.32.72.82.82.82.52.92.82.42.32.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:SupplementalRevenueMember ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:InvestmentPerformance, ajg:BrokerageSegment


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value1815182423191722171513151514
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.01.01.01.41.31.20.91.41.00.90.71.01.01.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.01.01.01.41.31.20.91.41.00.90.71.01.01.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:InvestmentPerformance ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:InvestmentPerformance, ajg:RiskManagementSegment


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value0.10.20.30.30.40.50.40.10.10.10.20.20.10.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:InvestmentPerformance ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:ProductAndServiceOther, us-gaap:Corporate


Revenue
Period End2020-09-302020-06-302019-12-312019-09-302019-06-302018-12-312018-09-302018-06-302017-06-30
Value-0.60.20.0-3.00.10.00.30.60.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.00.00.0-0.20.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.00.00.0-0.20.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:ProductAndServiceOther us-gaap:Corporate100.0100.00.0100.0100.00.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:PublicUtilitiesInventoryCoal, us-gaap:Corporate


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value310159181276386284372419492422412401430376
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.810.19.716.121.117.218.725.327.725.422.425.127.025.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.810.19.716.121.117.218.725.327.725.422.425.127.025.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:PublicUtilitiesInventoryCoal us-gaap:Corporate100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:OperatingSegments, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value13901610123512941201143511921195113113811001104910001195895938896878859877939825851835885751816795737564
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax71.974.472.570.075.876.969.365.568.269.460.459.060.265.156.058.960.253.462.159.265.863.563.857.464.661.065.661.862.661.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax71.974.472.570.075.876.969.365.568.269.460.459.060.265.156.058.960.253.462.159.265.863.563.857.464.661.065.661.862.661.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value281252256244223249252246242236236236237229222224216182297176176179181179189177154172172164
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax14.611.715.113.214.113.414.713.514.611.914.313.314.312.513.914.114.611.121.511.912.413.813.612.313.814.412.413.414.717.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax14.611.715.113.214.113.414.713.514.611.914.313.314.312.513.914.114.611.121.511.912.413.813.612.313.814.412.413.414.717.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Corporate


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value261302211310159181276383284372419492423412401430376351313428311295301440296303274318268186
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.514.012.416.810.19.716.121.017.218.725.327.725.522.425.127.025.321.422.628.921.822.722.630.321.624.622.024.822.820.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.514.012.416.810.19.716.121.017.218.725.327.725.522.425.127.025.321.422.628.921.822.722.630.321.624.622.024.822.820.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments us-gaap:Corporate100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:OperatingSegments, ajg:OtherForeign, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value5557614646475336383842313935342733
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.92.63.62.52.92.63.12.02.31.92.61.82.41.92.21.72.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.92.63.62.52.92.63.12.02.31.92.61.82.41.92.21.72.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments ajg:OtherForeign ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:AU, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value7054595656435352584649495343485052
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.72.53.53.13.62.33.12.93.52.33.02.83.22.43.03.23.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.72.53.53.13.62.33.12.93.52.33.02.83.22.43.03.23.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:AU ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:AU, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value3329252624212222202224212523211919
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.71.31.51.41.61.21.31.21.21.11.51.21.51.31.31.21.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.71.31.51.41.61.21.31.21.21.11.51.21.51.31.31.21.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:AU ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:CA, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value7967725758565352585750404742453536
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.13.14.23.13.73.03.12.93.52.93.02.32.92.32.82.22.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.13.14.23.13.73.03.12.93.52.93.02.32.92.32.82.22.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:CA ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:CA, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value1.41.41.41.41.51.01.31.01.11.21.30.91.21.01.11.40.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:CA ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:GB, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value326292247230260254247221248203173169204191164168184
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.913.514.512.516.513.614.412.215.010.210.59.512.310.410.310.612.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.913.514.512.516.513.614.412.215.010.210.59.512.310.410.310.612.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:GB ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:GB, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value1111119.88.211111010.0108.98.78.89.08.68.47.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.50.70.50.50.60.60.60.60.50.50.50.50.50.50.50.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.50.70.50.50.60.60.60.60.50.50.50.50.50.50.50.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:GB ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:NZ, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value4532383738283736413037353930343636
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.31.52.32.02.41.52.22.02.51.52.22.02.41.62.22.32.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.31.52.32.02.41.52.22.02.51.52.22.02.41.62.22.32.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:NZ ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:NZ, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value4.03.73.63.03.22.83.33.84.14.03.84.24.33.54.45.04.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.20.20.20.20.10.20.20.20.20.20.20.30.20.30.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.20.20.20.20.10.20.20.20.20.20.20.30.20.30.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:NZ ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:US, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value812110675686674010057467956851006648724615852568620552
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax42.051.144.446.946.853.943.443.641.350.639.140.737.146.435.538.937.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax42.051.144.446.946.853.943.443.641.350.639.140.737.146.435.538.937.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:US ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:US, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value231207214203185212214208206198198201197192186190185
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.09.612.611.011.711.412.511.412.510.012.011.311.910.511.712.012.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.09.612.611.011.711.412.511.412.510.012.011.311.910.511.712.012.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:US ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:US, us-gaap:Corporate


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value261302211310159181276383284372419492423412401430376
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.514.012.416.810.19.716.121.017.218.725.327.725.522.425.127.025.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.514.012.416.810.19.716.121.017.218.725.327.725.522.425.127.025.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:OperatingSegments country:US us-gaap:Corporate100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductOrService

ajg:BrokerFees


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value495459507491490464464433452422448383416386
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax26.829.027.228.626.928.023.326.125.525.424.424.026.126.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax26.829.027.228.626.928.023.326.125.525.424.424.026.126.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:BrokerFees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:Commissions


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value8898271017792809777940685707688839624637618
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax48.152.254.546.044.446.947.241.439.841.445.739.040.041.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax48.152.254.546.044.446.947.241.439.841.445.739.040.041.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:Commissions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:ContingentRevenue


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value3437452730294815252134212121
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.92.42.41.61.71.82.40.91.41.31.91.31.41.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.92.42.41.61.71.82.40.91.41.31.91.31.41.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:ContingentRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:GainsOnDivestitures


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3.41.00.2133.31.9570.60.66.12.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.00.80.20.12.90.00.00.40.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.00.80.20.12.90.00.00.40.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:GainsOnDivestitures100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:NetGainsOnDivestitures


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3.41.00.2133.31.9570.60.66.12.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.00.80.20.12.90.00.00.40.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.00.80.20.12.90.00.00.40.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:NetGainsOnDivestitures100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:Reimbursements


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value4132373734333334373534333335
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.22.02.02.21.92.01.72.12.12.11.92.12.12.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.22.02.02.21.92.01.72.12.12.11.92.12.12.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:Reimbursements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:SupplementalRevenueMember


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value5450595749465645434852383635
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.03.23.23.32.72.82.82.82.52.92.82.42.32.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.03.23.23.32.72.82.82.82.52.92.82.42.32.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:SupplementalRevenueMember100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentPerformance


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value1916182524191822181513161514
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.01.01.01.51.31.20.91.41.01.00.71.01.01.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.01.01.01.51.31.20.91.41.01.00.71.01.01.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:InvestmentPerformance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductAndServiceOther


Revenue
Period End2020-09-302020-06-302019-12-312019-09-302019-06-302018-12-312018-09-302018-06-302017-06-30
Value-0.60.20.0-3.00.10.00.30.60.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.00.00.0-0.20.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.00.00.0-0.20.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductAndServiceOther100.0100.00.0100.0100.00.0100.0100.0100.0

us-gaap:PublicUtilitiesInventoryCoal


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value310159181276386284372419492422412401430376
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.810.19.716.121.117.218.725.327.725.422.425.127.025.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax16.810.19.716.121.117.218.725.327.725.422.425.127.025.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:PublicUtilitiesInventoryCoal100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:StatementGeographical

ajg:OtherForeign


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value555761464647533638384231393534273331
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.92.63.62.52.92.63.12.02.31.92.61.82.41.92.21.72.31.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.92.63.62.52.92.63.12.02.31.92.61.82.41.92.21.72.31.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax ajg:OtherForeign100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:AU


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1038385828164757578687370796769697159
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.43.85.04.55.23.54.44.14.83.44.43.94.83.74.44.44.83.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.43.85.04.55.23.54.44.14.83.44.43.94.83.74.44.44.83.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:AU100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:CA


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value816873585957545359585141494346363732
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.23.24.33.23.83.13.22.93.62.93.12.33.02.42.92.32.52.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.23.24.33.23.83.13.22.93.62.93.12.33.02.42.92.32.52.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:CA100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:GB


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value337303258240269265258232258213182178213200173177191167
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.514.015.213.017.014.215.012.715.610.711.010.012.810.910.811.112.910.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.514.015.213.017.014.215.012.715.610.711.010.012.810.910.811.112.910.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:GB100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:NZ


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value493642404130413945344139433338414128
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.61.72.52.22.61.62.42.22.71.72.52.22.61.82.42.62.81.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.61.72.52.22.61.62.42.22.71.72.52.22.61.82.42.62.81.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:NZ100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value130516161181138010861400123713871176157712651418123514571156124111141327
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax67.574.769.474.768.675.071.976.071.079.276.479.874.479.372.377.974.880.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax67.574.769.474.768.675.071.976.071.079.276.479.874.479.372.377.974.880.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:US100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenues

us-gaap:Revenues

us-gaap:Revenues


Revenues
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value19332165170318491584186617211825165719901657177816601837159915841563141213851482142713001334145413711231124512861179915890835779674673650649546578562546447459463459482
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.099.4105.085.8100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value27817244142233121814213062083619634191731920018631163341611416230161271289712810125691178011489112001138410712109131051010716973010010998810019727568605970556252255352500951334602448342474581369135963250
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:VariableInterestEntityPrimaryBeneficiary, ajg:ChemModCleanCoalVenture


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-31
Value191614
Percentage of Assets0.10.10.1
Percentage of Assets0.10.10.1
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary ajg:ChemModCleanCoalVenture100.0100.0100.0

us-gaap:Assets us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, ajg:BrokerageSegment


Assetsus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value2185821242191851864118405181151674116261164641598113785137001377913784103361027510052942291838972922586818969863888948092841383778017577155224196
Percentage of Assets78.687.085.985.586.486.985.384.885.885.884.485.084.985.580.180.280.080.079.980.181.081.082.282.283.083.284.083.980.079.380.578.4
Percentage of Assets78.687.085.985.586.486.985.384.885.885.884.485.084.985.580.180.280.080.079.980.181.081.082.282.283.083.284.083.980.079.380.578.4
Percentage of Assets us-gaap:OperatingSegments ajg:BrokerageSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, ajg:RiskManagementSegment


Assetsus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value10581028973964929909898920847806748748739735735733707691666679663690660640623571547621611598544498
Percentage of Assets3.84.24.44.44.44.44.64.84.44.34.64.64.64.65.75.75.65.95.86.15.86.46.06.15.85.95.56.26.18.27.99.3
Percentage of Assets3.84.24.44.44.44.44.64.84.44.34.64.64.64.65.75.75.65.95.86.15.86.46.06.15.85.95.56.26.18.27.99.3
Percentage of Assets us-gaap:OperatingSegments ajg:RiskManagementSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:Corporate


Assetsus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value4900214421722209197118111994199118881843180016651712160718251801180916661639154814941340128412311198106710489891390905793656
Percentage of Assets17.68.89.710.19.38.710.210.49.89.911.010.310.510.014.214.114.414.114.313.813.112.511.811.711.211.010.59.913.912.411.612.3
Percentage of Assets17.68.89.710.19.38.710.210.49.89.911.010.310.510.014.214.114.414.114.313.813.112.511.811.711.211.010.59.913.912.411.612.3
Percentage of Assets us-gaap:OperatingSegments us-gaap:Corporate100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:OperatingSegments, ajg:OtherForeign, ajg:BrokerageSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value959817593461402
Percentage of Assets4.34.23.63.63.5
Percentage of Assets4.34.23.63.63.5
Percentage of Assets us-gaap:OperatingSegments ajg:OtherForeign ajg:BrokerageSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:AU, ajg:BrokerageSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1373121710961102931
Percentage of Assets6.16.26.78.68.1
Percentage of Assets6.16.26.78.68.1
Percentage of Assets us-gaap:OperatingSegments country:AU ajg:BrokerageSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:AU, ajg:RiskManagementSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value8990474856
Percentage of Assets0.40.50.30.40.5
Percentage of Assets0.40.50.30.40.5
Percentage of Assets us-gaap:OperatingSegments country:AU ajg:RiskManagementSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:CA, ajg:BrokerageSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1053913783743584
Percentage of Assets4.74.74.85.85.1
Percentage of Assets4.74.74.85.85.1
Percentage of Assets us-gaap:OperatingSegments country:CA ajg:BrokerageSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:CA, ajg:RiskManagementSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value4.83.14.46.82.8
Percentage of Assets0.00.00.00.10.0
Percentage of Assets0.00.00.00.10.0
Percentage of Assets us-gaap:OperatingSegments country:CA ajg:RiskManagementSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:GB, ajg:BrokerageSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value61354964375834963172
Percentage of Assets27.525.323.027.127.6
Percentage of Assets27.525.323.027.127.6
Percentage of Assets us-gaap:OperatingSegments country:GB ajg:BrokerageSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:GB, ajg:RiskManagementSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1391261039161
Percentage of Assets0.60.60.60.70.5
Percentage of Assets0.60.60.60.70.5
Percentage of Assets us-gaap:OperatingSegments country:GB ajg:RiskManagementSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:NZ, ajg:BrokerageSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value766695688709672
Percentage of Assets3.43.54.25.55.8
Percentage of Assets3.43.54.25.55.8
Percentage of Assets us-gaap:OperatingSegments country:NZ ajg:BrokerageSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:NZ, ajg:RiskManagementSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value242221184.4
Percentage of Assets0.10.10.10.10.0
Percentage of Assets0.10.10.10.10.0
Percentage of Assets us-gaap:OperatingSegments country:NZ ajg:RiskManagementSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:US, ajg:BrokerageSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value88978132686558905545
Percentage of Assets39.841.442.045.748.3
Percentage of Assets39.841.442.045.748.3
Percentage of Assets us-gaap:OperatingSegments country:US ajg:BrokerageSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:US, ajg:RiskManagementSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value716655571572545
Percentage of Assets3.23.33.54.44.7
Percentage of Assets3.23.33.54.44.7
Percentage of Assets us-gaap:OperatingSegments country:US ajg:RiskManagementSegment100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, country:US, us-gaap:Corporate


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value21721994180017661548
Percentage of Assets9.710.211.013.713.5
Percentage of Assets9.710.211.013.713.5
Percentage of Assets us-gaap:OperatingSegments country:US us-gaap:Corporate100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:StatementGeographical

ajg:OtherForeign


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value959817593446348222224171
Percentage of Assets4.34.23.63.53.02.02.22.5
Percentage of Assets4.34.23.63.53.02.02.22.5
Percentage of Assets ajg:OtherForeign100.0100.0100.0100.0100.0100.0100.0100.0

country:AU


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value1462130711431110951951642277260
Percentage of Assets6.66.77.08.68.38.76.44.14.9
Percentage of Assets6.66.77.08.68.38.76.44.14.9
Percentage of Assets country:AU100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:CA


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value10589167877335765781031108102
Percentage of Assets4.74.74.85.75.05.310.31.61.9
Percentage of Assets4.74.74.85.75.05.310.31.61.9
Percentage of Assets country:CA100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:GB


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value627450913862271223832652245018781170946
Percentage of Assets28.125.923.621.020.724.324.527.421.921.1
Percentage of Assets28.125.923.621.020.724.324.527.421.921.1
Percentage of Assets country:GB100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:NZ


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value7907187097266736276151.8
Percentage of Assets3.53.74.35.65.95.76.20.0
Percentage of Assets3.53.74.35.65.95.76.20.0
Percentage of Assets country:NZ100.0100.0100.0100.0100.0100.0100.0100.0

country:US


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value117861078292377168655658825046442236753202
Percentage of Assets52.854.956.655.657.153.950.464.568.771.4
Percentage of Assets52.854.956.655.657.153.950.464.568.771.4
Percentage of Assets country:US100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Liabilities

us-gaap:Liabilities

us-gaap:Liabilities


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1946317635160981599615771157661441914261142521367311764115021171711543873286388659805378337459772870607225680270046511678067326769513147754038386035603693337336603246323930273379254424892357
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets70.072.272.173.374.075.773.474.474.273.472.071.472.271.667.767.468.968.468.266.667.965.966.264.765.466.967.767.467.670.569.667.669.468.169.067.371.370.572.371.373.768.969.272.5

us-gaap:Liabilities us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:VariableInterestEntityNotPrimaryBeneficiary, ajg:VentureCapitalFundsAndOther


Liabilitiesus-gaap:
Period End2020-12-31
Value0.5
Percentage of Liabilities0.0
Percentage of Assets0.0
Percentage of Assets us-gaap:VariableInterestEntityNotPrimaryBeneficiary ajg:VentureCapitalFundsAndOther0.0

us-gaap:VariableInterestEntityPrimaryBeneficiary, ajg:ChemModCleanCoalVenture


Liabilitiesus-gaap:
Period End2020-12-312019-12-312018-12-31
Value4.42.81.4
Percentage of Liabilities0.00.00.0
Percentage of Assets0.00.00.0
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary ajg:ChemModCleanCoalVenture23.217.210.0

us-gaap:Liabilities us-gaap:InvestmentType, us-gaap:LineOfCreditFacility

us-gaap:StandbyLettersOfCredit, ajg:UnsecuredMulticurrencyCreditAgreement


Liabilitiesus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value1716151312121211111111109.79.38.99.0
Percentage of Liabilities0.10.10.10.20.20.20.20.20.20.20.20.20.10.10.10.2
Percentage of Assets0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets us-gaap:StandbyLettersOfCredit ajg:UnsecuredMulticurrencyCreditAgreement0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value27817244142233121814213062083619634191731920018631163341611416230161271289712810125691178011489112001138410712109131051010716973010010998810019727568605970556252255352500951334602448342474581369135963250
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-312007-12-31
Value8312673161865771548850295155484348794880449845444443451441054110384436623596368635993597363836523638314532293256324921442085193217021664165816361472135612431219120211471106892738715
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets29.927.627.726.525.824.126.325.325.426.227.528.227.428.031.832.130.631.131.332.931.633.633.334.834.032.332.332.632.429.530.432.430.631.931.032.728.729.527.728.726.331.130.827.50.00.0

Assets Current

us-gaap:AssetsCurrent

us-gaap:AssetsCurrent


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value15939126671112411200107601052791179328954796698118808483658533517050875107448344164213448539394335402042613594381139724440319828752546260223012429232426312225219920882416174917261540
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets57.351.949.851.350.550.546.448.749.751.949.750.251.552.940.139.740.638.138.437.639.436.839.738.239.836.938.139.844.344.041.942.746.844.045.446.451.348.349.149.252.747.448.047.4

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashAndCashEquivalentsAtCarryingValue


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value3204526664629349352604578512871607605652697681564587564545531411425480369321276314290973739298286240224302305282301291241263333249296230227205194255
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets11.52.23.02.91.61.73.13.02.74.73.73.84.04.35.34.44.74.84.74.73.64.04.43.53.02.83.12.99.710.24.34.84.34.35.66.15.56.66.55.75.79.06.90.00.00.06.30.00.0

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-31
Value637533603574347430022633262326072546254022362260234421082305218020681822193718921682
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets22.913.816.015.914.112.613.413.613.313.613.714.014.413.117.917.016.515.516.917.316.8

Other Assets Current

us-gaap:OtherAssetsCurrent

us-gaap:OtherAssetsCurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value116999711131023884799107410369938751024951878749708679664594633601605503709700731587666670360289261260203227179182157165188146127117126117
Percentage of OtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.24.15.04.74.13.85.55.45.24.76.35.95.44.65.55.35.35.05.55.45.34.76.56.76.86.06.76.73.64.03.84.43.74.43.43.63.13.64.23.52.83.23.53.6

Machinery And Equipment Gross

us-gaap:MachineryAndEquipmentGross

us-gaap:MachineryAndEquipmentGross


Machinery
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value3332302822212316151111
Percentage of MachineryAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.20.20.20.20.20.20.20.30.30.3

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:PropertyPlantAndEquipmentGross


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value11791059941880789601548445363336277
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.35.45.86.86.95.55.56.56.87.57.7

Furniture And Fixtures Gross

us-gaap:FurnitureAndFixturesGross

us-gaap:FurnitureAndFixturesGross


Furniture
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value13812611611296928978747166
Percentage of FurnitureAndFixturesGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.60.60.70.90.80.80.91.11.41.61.9

Leasehold Improvements Gross

us-gaap:LeaseholdImprovementsGross

us-gaap:LeaseholdImprovementsGross


Leasehold
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value16615013212410710610277524541
Percentage of LeaseholdImprovementsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.80.81.00.91.01.01.11.01.01.1

Construction In Progress Gross

us-gaap:ConstructionInProgressGross

us-gaap:ConstructionInProgressGross


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value141814201046
Percentage of ConstructionInProgressGross100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.20.10.4

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value728591504468411398353285258245201
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.33.03.13.63.63.73.54.24.85.55.6

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:PropertyPlantAndEquipmentNet


Property
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value45444945045846145446745845845043642942742441241338737537721321321820220019819019519619316516014812310810510110095919087797580
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.61.82.02.12.22.22.42.42.42.42.72.72.62.63.23.23.13.23.31.91.92.01.91.91.82.02.02.01.92.32.32.52.22.12.02.02.02.12.02.11.92.22.12.5

Goodwill

us-gaap:Goodwill

us-gaap:Goodwill


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value66306510612758325756555556185314524148004625450144034236419741603989389637673762371636933662357935693418344932963027214221451771150614681472137312851195115510921072925883742
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets23.826.727.426.727.026.728.627.727.325.828.327.927.126.332.532.531.733.132.833.632.634.533.634.133.335.134.533.030.229.431.329.727.128.127.527.425.026.025.825.723.425.124.622.8

us-gaap:Goodwill us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, ajg:BrokerageSegment


Goodwillus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value605355484573415237363635342721221451
Percentage of Goodwill98.898.898.998.999.299.399.499.098.6
Percentage of Assets27.128.328.032.232.533.334.230.927.1
Percentage of Assets us-gaap:OperatingSegments ajg:BrokerageSegment31.633.133.240.240.740.540.738.434.6

us-gaap:OperatingSegments, ajg:RiskManagementSegment


Goodwillus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value706649422827222221
Percentage of Goodwill1.21.21.11.00.70.70.61.01.4
Percentage of Assets0.30.30.30.30.20.30.20.30.4
Percentage of Assets us-gaap:OperatingSegments ajg:RiskManagementSegment7.27.46.65.84.24.14.04.14.3

us-gaap:OperatingSegments, us-gaap:Corporate


Goodwillus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value2.93.02.73.02.8
Percentage of Goodwill0.00.10.10.10.1
Percentage of Assets0.00.00.00.00.0
Percentage of Assets us-gaap:OperatingSegments us-gaap:Corporate0.10.20.10.20.2

us-gaap:Goodwill us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-31
Value65246418605357615686548855485246519047484573445243584189415241143946386537363734368736643635355235413392342732733005211921221750148414471451135312651174113610741055866732
Percentage of Goodwill98.498.698.898.898.898.898.898.799.098.998.998.999.098.998.998.998.999.299.299.299.299.299.399.299.299.399.499.399.399.099.098.898.698.698.698.598.498.398.498.398.498.198.7
Percentage of Assets23.526.327.126.426.726.328.327.427.025.528.027.626.926.032.232.131.432.832.533.332.434.233.333.833.134.934.232.830.029.130.929.326.727.727.127.024.625.525.425.323.024.122.5
Percentage of Assets ajg:BrokerageSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.039.037.336.638.437.534.336.634.635.332.034.134.033.429.933.831.3

ajg:RiskManagementSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-31
Value10289706766636664484949464243424340282828282827272725222222222221212121202020181817179.7
Percentage of Goodwill1.61.41.21.21.21.11.21.20.91.01.11.01.01.01.01.01.00.70.70.80.80.80.70.80.80.70.60.70.71.01.01.21.41.41.41.51.61.71.61.71.61.91.3
Percentage of Assets0.40.40.30.30.30.30.30.30.30.30.30.30.30.30.30.30.30.20.20.30.30.30.30.30.30.30.20.20.20.30.30.40.40.40.40.40.40.40.40.40.40.50.3
Percentage of Assets ajg:RiskManagementSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.03.83.93.94.13.94.04.24.33.83.83.93.53.73.33.32.6

us-gaap:Corporate


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-312012-12-31
Value2.92.92.92.92.82.83.03.13.12.72.72.62.82.93.02.92.92.92.80.00.00.00.00.00.00.00.00.0
Percentage of Goodwill0.00.00.00.00.00.10.10.10.10.10.10.10.10.10.10.10.10.10.10.00.00.00.00.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:Corporate0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Goodwill us-gaap:StatementGeographical

ajg:OtherForeign


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value1521491511461431261311151161121121181181041011038986826948494242
Percentage of Goodwill2.32.32.52.52.52.32.32.22.22.32.42.62.72.52.42.52.22.22.21.81.31.31.21.2
Percentage of Assets0.50.60.70.70.70.60.70.60.60.60.70.70.70.70.80.80.70.70.70.60.40.50.40.4
Percentage of Assets ajg:OtherForeign0.00.015.80.00.00.016.10.00.00.019.00.00.00.022.70.00.00.023.70.00.00.019.118.8

country:AU


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value48047847344442736742741441640940641140041441642740541038240039339738034237232433637
Percentage of Goodwill7.27.47.77.67.46.67.67.87.98.58.89.19.19.89.910.310.210.510.210.610.610.810.49.610.49.59.81.7
Percentage of Assets1.72.02.12.02.01.82.22.22.22.22.52.62.52.63.23.33.23.53.33.63.53.73.53.33.53.33.40.5
Percentage of Assets country:AU0.00.032.40.00.00.032.60.00.00.035.60.00.00.037.50.00.00.040.20.00.00.040.00.00.00.052.513.4

country:CA


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value54051549245043941845444544643737837336036737534529529329229830229728229331629931826
Percentage of Goodwill8.17.98.07.77.67.58.18.48.59.18.28.38.28.78.98.37.47.57.87.98.18.07.78.28.98.89.21.2
Percentage of Assets1.92.12.22.12.12.02.32.32.32.32.32.32.22.32.92.72.42.52.52.72.72.82.62.83.03.13.20.4
Percentage of Assets country:CA0.00.046.60.00.00.049.60.00.00.048.10.00.00.051.20.00.00.050.70.00.00.048.90.00.00.030.924.6

country:GB


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value161816011343127412501199119011501153793762733739783745745699672666688705749782806828788820833882571597226
Percentage of Goodwill24.424.621.921.821.721.621.221.722.016.516.516.316.818.517.817.917.517.217.718.319.020.321.422.523.223.123.825.329.126.727.815.3
Percentage of Assets5.86.66.05.85.95.86.16.06.04.34.74.64.64.95.85.85.65.75.86.16.27.07.27.77.78.18.28.38.87.98.74.2
Percentage of Assets country:GB0.00.021.40.00.00.023.40.00.00.019.80.00.00.027.50.00.00.028.00.00.00.029.50.00.00.033.50.00.00.031.819.3

country:NZ


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value230230232216211191218206218223219207214224218226224208205216210200204258
Percentage of Goodwill3.53.53.83.73.73.43.93.94.24.74.84.64.95.35.25.45.65.45.45.85.75.45.67.5
Percentage of Assets0.80.91.01.01.00.91.11.11.11.21.31.31.31.41.71.81.81.81.81.91.91.91.92.6
Percentage of Assets country:NZ0.00.029.40.00.00.030.30.00.00.031.00.00.00.030.10.00.00.030.50.00.00.032.642.0

country:US


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value36083535343333003284325231962983289128242744265625702341234023112274222521382088205519991970190818071710167215921551150514691177
Percentage of Goodwill54.454.356.056.657.058.556.956.155.258.859.359.058.455.355.755.657.057.156.855.555.354.153.853.350.650.048.548.351.270.368.579.9
Percentage of Assets13.014.515.415.115.415.616.315.615.115.216.816.515.814.518.118.018.118.918.618.618.118.718.118.216.917.616.715.915.520.721.422.0
Percentage of Assets country:US0.00.029.10.00.00.029.60.00.00.029.70.00.00.032.60.00.00.032.60.00.00.033.50.00.00.033.10.00.00.033.232.0

us-gaap:Goodwill us-gaap:StatementGeographical, us-gaap:StatementBusinessSegments

ajg:OtherForeign, ajg:BrokerageSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value14914614814314012312811211310911011611599
Percentage of Goodwill2.32.22.42.52.42.22.32.12.22.32.42.62.62.4
Percentage of Assets0.50.60.70.70.70.60.70.60.60.60.70.70.70.8
Percentage of Assets ajg:OtherForeign ajg:BrokerageSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

ajg:OtherForeign, us-gaap:Corporate


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value2.92.92.92.92.82.83.03.13.12.72.72.62.83.0
Percentage of Goodwill0.00.00.00.00.00.10.10.10.10.10.10.10.10.1
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets ajg:OtherForeign us-gaap:Corporate0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

country:AU, ajg:BrokerageSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value468467462433417358416404415409406411400416
Percentage of Goodwill7.17.27.57.47.26.57.47.67.98.58.89.19.19.9
Percentage of Assets1.71.92.12.02.01.72.12.12.22.22.52.62.53.2
Percentage of Assets country:AU ajg:BrokerageSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

country:AU, ajg:RiskManagementSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value11111110109.010100.30.30.3
Percentage of Goodwill0.20.20.20.20.20.20.20.20.00.00.0
Percentage of Assets0.00.00.10.00.00.00.10.10.00.00.0
Percentage of Assets country:AU ajg:RiskManagementSegment0.00.00.00.00.00.00.00.00.00.00.0

country:CA, ajg:BrokerageSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value540515492450439418454445446437378373360374
Percentage of Goodwill8.17.98.07.77.67.58.18.48.59.18.28.38.28.9
Percentage of Assets1.92.12.22.12.12.02.32.32.32.32.32.32.22.9
Percentage of Assets country:CA ajg:BrokerageSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

country:GB, ajg:BrokerageSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value160215851328126012371186117711381144784753726732738
Percentage of Goodwill24.224.421.721.621.521.421.021.421.816.316.316.116.617.6
Percentage of Assets5.86.55.95.85.85.76.05.96.04.24.64.54.55.7
Percentage of Assets country:GB ajg:BrokerageSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

country:GB, ajg:RiskManagementSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value15151513131212128.89.69.27.07.17.2
Percentage of Goodwill0.20.20.20.20.20.20.20.20.20.20.20.20.20.2
Percentage of Assets0.10.10.10.10.10.10.10.10.00.10.10.00.00.1
Percentage of Assets country:GB ajg:RiskManagementSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

country:NZ, ajg:BrokerageSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value220220221206201182208196207213209197204209
Percentage of Goodwill3.33.43.63.53.53.33.73.74.04.44.54.44.65.0
Percentage of Assets0.80.91.00.90.90.91.11.01.11.11.31.21.31.6
Percentage of Assets country:NZ ajg:BrokerageSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

country:NZ, ajg:RiskManagementSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value10101010.09.88.8109.510101010109.6
Percentage of Goodwill0.20.20.20.20.20.20.20.20.20.20.20.20.20.2
Percentage of Assets0.00.00.00.00.00.00.10.00.10.10.10.10.10.1
Percentage of Assets country:NZ ajg:RiskManagementSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

country:US, ajg:BrokerageSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value35433483339932673250321931632950286127942715262625452280
Percentage of Goodwill53.453.555.556.056.558.056.355.554.658.258.758.457.854.3
Percentage of Assets12.714.315.215.015.315.516.115.414.915.016.616.315.717.7
Percentage of Assets country:US ajg:BrokerageSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

country:US, ajg:RiskManagementSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value6552333333333333292929292525
Percentage of Goodwill1.00.80.50.60.60.60.60.60.60.60.60.70.60.6
Percentage of Assets0.20.20.10.20.20.20.20.20.20.20.20.20.20.2
Percentage of Assets country:US ajg:RiskManagementSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill


Intangible
Period End2020-12-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2399222622462318207320081841177317721731163916441671166216821627162916591672169817411761172317761771163110931078918784768809722644598561556562489483438
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets10.710.410.811.810.810.59.910.911.010.710.212.813.013.214.314.214.614.615.615.616.616.417.717.717.716.315.015.715.414.114.715.114.412.613.012.513.112.313.313.413.5

us-gaap:IntangibleAssetsNetExcludingGoodwill us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, ajg:BrokerageSegment


Intangible
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value23762289175316301613167717611061791
Percentage of IntangibleAssetsNetExcludingGoodwill99.098.898.999.199.298.899.298.497.8
Percentage of Assets10.611.710.712.614.015.417.615.514.8
Percentage of Assets us-gaap:OperatingSegments ajg:BrokerageSegment12.413.712.715.817.618.720.919.218.9

us-gaap:OperatingSegments, ajg:RiskManagementSegment


Intangible
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value232819141321141718
Percentage of IntangibleAssetsNetExcludingGoodwill1.01.21.10.90.81.20.81.62.2
Percentage of Assets0.10.10.10.10.10.20.10.30.3
Percentage of Assets us-gaap:OperatingSegments ajg:RiskManagementSegment2.43.22.61.92.13.22.73.23.6

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet

us-gaap:FiniteLivedIntangibleAssetsNet


Finite
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value24472478239921952318918784768809722644598561556562483
Percentage of FiniteLivedIntangibleAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets8.810.210.710.111.815.414.114.715.114.412.613.012.513.112.313.4

us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass

ajg:ExpirationLists


Finite
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-31
Value23622391231621242241895763747784699624577540535473
Percentage of FiniteLivedIntangibleAssetsNet96.696.596.596.896.797.597.297.396.996.896.896.696.396.397.9
Percentage of Assets8.59.810.49.711.415.013.714.314.714.012.212.612.112.613.2
Percentage of Assets ajg:ExpirationLists0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NoncompeteAgreements


Finite
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-31
Value25281811156.86.36.37.67.55.94.95.04.54.1
Percentage of FiniteLivedIntangibleAssetsNet1.11.10.80.50.70.70.80.80.91.00.90.80.90.80.8
Percentage of Assets0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets us-gaap:NoncompeteAgreements0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TradeNames


Finite
Period End2021-06-302021-03-312020-12-312020-09-302019-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-31
Value58596559611515141715141515166.1
Percentage of FiniteLivedIntangibleAssetsNet2.42.42.72.72.61.72.01.92.22.22.32.62.82.91.3
Percentage of Assets0.20.20.30.30.30.30.30.30.30.30.30.30.40.40.2
Percentage of Assets us-gaap:TradeNames0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Deferred Tax Assets Liabilities Net

us-gaap:DeferredTaxAssetsLiabilitiesNet

us-gaap:DeferredTaxAssetsLiabilitiesNet


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value978818699573425291116155156191211
Percentage of DeferredTaxAssetsLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.44.24.34.43.72.71.22.32.94.35.9

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OperatingLeaseRightOfUseAsset


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312019-01-01
Value358370373346362374393384368368379
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.31.51.71.61.71.82.02.01.92.00.0

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent

us-gaap:OtherAssetsNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value860850769732727674773660670630573584586585567559561536504630606528492480487408385399397383320302270319283245232251235204208204181177
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.13.53.43.43.43.23.93.43.53.43.53.63.63.64.44.44.54.64.45.65.34.94.54.64.64.23.84.04.05.34.75.14.96.15.34.94.55.55.34.84.65.55.15.5

Liabilities Current

us-gaap:LiabilitiesCurrent

us-gaap:LiabilitiesCurrent


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value120211151610135101179864983789218910893286377693742275687742491247054858478446114398438340224191372939053438364237693875303332842577234322152362209024422044207319432287148515771474
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets43.247.245.446.446.347.245.446.546.546.447.146.146.648.038.136.738.640.640.139.338.537.538.435.536.435.336.437.738.741.747.943.242.142.444.141.747.644.446.245.849.940.243.945.4

Operating Lease Liability Current

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OperatingLeaseLiabilityCurrent


Operating
Period End2020-12-31
Value88
Percentage of OperatingLeaseLiabilityCurrent100.0
Percentage of Assets0.4

Long Term Debt

us-gaap:LongTermDebt

us-gaap:LongTermDebt


Long
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value19181919266246363217
Percentage of LongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.20.20.60.50.50.60.4

us-gaap:LongTermDebt us-gaap:Collateral, us-gaap:ShortTermDebtType

us-gaap:CollateralPledged, us-gaap:LetterOfCredit


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302018-09-30
Value1.01.01.01.00.91.3
Percentage of LongTermDebt0.00.05.10.00.00.0
Percentage of Assets0.00.00.00.00.00.0
Percentage of Assets us-gaap:CollateralPledged us-gaap:LetterOfCredit0.00.00.00.00.00.0

us-gaap:LongTermDebt us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:LineOfCreditFacility

us-gaap:FairValueInputsLevel3, ajg:NotePurchaseAgreement


Long
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value4348392331982798245024002400212521252125212521252125212522251525925925925725725
Percentage of LongTermDebt22183.721205.416070.414203.09107.80.00.00.03383.80.00.00.04609.50.00.00.02534.20.00.00.02237.7
Percentage of Assets19.520.019.621.721.321.421.119.819.520.219.821.821.221.322.221.013.515.516.613.913.5
Percentage of Assets us-gaap:FairValueInputsLevel3 ajg:NotePurchaseAgreement0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LongTermDebt us-gaap:LineOfCreditFacility

ajg:CollateralToClaimFundsHeldInFiduciaryCapacityByRecentAcquisitionExpiresTwoThousandTwentyOne


Long
Period End2020-12-31
Value1.0
Percentage of LongTermDebt5.1
Percentage of Assets0.0
Percentage of Assets ajg:CollateralToClaimFundsHeldInFiduciaryCapacityByRecentAcquisitionExpiresTwoThousandTwentyOne0.0

ajg:CreditEnhancementUnderLettersOfCreditForOurCaptiveInsuranceOperationsToMeetMinimumStatutoryCapitalRequirementsExpiresAfterTwoThousandAndTwentyFive


Long
Period End2020-12-31
Value7.5
Percentage of LongTermDebt38.3
Percentage of Assets0.0
Percentage of Assets ajg:CreditEnhancementUnderLettersOfCreditForOurCaptiveInsuranceOperationsToMeetMinimumStatutoryCapitalRequirementsExpiresAfterTwoThousandAndTwentyFive0.0

ajg:CreditSupportUnderLettersOfCreditForDeductiblesDueByUsOnOurOwnInsuranceCoverageExpiresAfterTwoThousandAndTwentyFive


Long
Period End2020-12-31
Value9.4
Percentage of LongTermDebt48.0
Percentage of Assets0.0
Percentage of Assets ajg:CreditSupportUnderLettersOfCreditForDeductiblesDueByUsOnOurOwnInsuranceCoverageExpiresAfterTwoThousandAndTwentyFive0.0

ajg:CreditSupportUnderLettersOfCreditInLieuOfSecurityDepositForAcquisitionLeaseExpiresTwoThousandAndTwentyFive


Long
Period End2020-12-31
Value0.5
Percentage of LongTermDebt2.6
Percentage of Assets0.0
Percentage of Assets ajg:CreditSupportUnderLettersOfCreditInLieuOfSecurityDepositForAcquisitionLeaseExpiresTwoThousandAndTwentyFive0.0

ajg:FinancialGuaranteesOfLoansToFiveCanadianBasedEmployeesTrigger


Long
Period End2020-12-31
Value1.2
Percentage of LongTermDebt6.1
Percentage of Assets0.0
Percentage of Assets ajg:FinancialGuaranteesOfLoansToFiveCanadianBasedEmployeesTrigger0.0

us-gaap:LongTermDebt us-gaap:LineOfCreditFacility, us-gaap:ShortTermDebtType

ajg:RentCaptiveFacility, us-gaap:LetterOfCredit


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value4.34.37.57.57.57.46.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.36.2
Percentage of LongTermDebt0.00.038.30.00.00.034.10.00.00.031.70.00.00.032.00.00.00.023.40.00.00.010.00.00.00.013.70.00.00.017.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets ajg:RentCaptiveFacility us-gaap:LetterOfCredit0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

ajg:SelfInsuranceDeductibles, us-gaap:LetterOfCredit


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value9.49.49.49.49.49.59.4101010109.79.79.712131212121211111111109.79.39.89.89.8
Percentage of LongTermDebt0.00.048.00.00.00.050.80.00.00.051.30.00.049.20.00.00.045.70.00.00.018.80.00.00.021.00.00.00.026.8
Percentage of Assets0.00.00.00.00.00.00.00.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets ajg:SelfInsuranceDeductibles us-gaap:LetterOfCredit0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Long Term Debt Noncurrent

us-gaap:LongTermDebtNoncurrent

us-gaap:LongTermDebtNoncurrent


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value571243664266426543154315381638153815369030913141314127922691274126442144214420442344207120752125212521252125212521251425825825925725725725675675675675675675550550
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets20.517.919.119.620.320.719.419.919.919.818.919.519.417.320.921.421.018.218.718.320.619.319.020.219.821.821.221.321.219.612.013.816.613.913.514.513.114.715.115.914.718.315.316.9

Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value2730335253545417646420
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.20.20.40.50.50.50.31.21.40.6

Minority Interest

us-gaap:MinorityInterest

us-gaap:MinorityInterest


Minority
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value414846464540606868777068696959626564595455554955737475
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.20.20.20.20.20.30.40.40.40.40.40.40.40.50.50.50.60.50.50.50.50.50.50.70.80.8

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OtherLiabilitiesNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value13651373131112551218122512711127110193790086293193311281191115611231077101510009669589489749471012837769672665635591620605557543526491409417383362333
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.95.65.95.85.75.96.55.95.75.05.55.35.75.88.79.39.29.59.49.18.89.08.89.09.19.710.18.47.79.29.710.610.611.911.311.110.611.411.09.69.110.410.110.2

Operating Lease Liability Noncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value302315320292307319340335327
Percentage of OperatingLeaseLiabilityNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.11.31.41.31.41.51.71.71.7

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo


Lessee
Period End2020-12-31
Value93
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0
Percentage of Assets0.4

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree


Lessee
Period End2020-12-31
Value75
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0
Percentage of Assets0.3

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour


Lessee
Period End2020-12-31
Value54
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0
Percentage of Assets0.2

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive


Lessee
Period End2020-12-31
Value41
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0
Percentage of Assets0.2

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive


Lessee
Period End2020-12-31
Value77
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0
Percentage of Assets0.3

Operating Lease Liability

us-gaap:OperatingLeaseLiability

us-gaap:OperatingLeaseLiability


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312019-01-01
Value409427417402410420
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0100.0
Percentage of Assets1.82.22.22.12.20.0

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue


Lessee
Period End2020-12-31
Value451
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0
Percentage of Assets2.0

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount


Lessee
Period End2020-12-31
Value42
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount100.0
Percentage of Assets0.2

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-312007-12-31
Value8312673161865771548850295155484348794880449845444443451441054110384436623596368635993597363836523638314532293256324921442085193217021664165816361472135612431219120211471106892738715
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets29.927.627.726.525.824.126.325.325.426.227.528.227.428.031.832.130.631.131.332.931.633.633.334.834.032.332.332.632.429.530.432.430.631.931.032.728.729.527.728.726.331.130.827.50.00.0

Stockholders Equity Including Portion Attributable To Noncontrolling Interest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-31
Value83546779623258185534507052154912494749584569461245134584416441723910372736553741365536523688370737113219330521141672
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.027.827.926.726.024.326.625.625.826.628.028.627.828.432.332.631.131.631.833.432.134.133.835.334.633.133.030.831.3

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-31
Value-530.5-527.8-643.6-870.4-982.2-1231.1-759.6-925.1-802.5-721.5-785.6-673.4-651.4-499.5-559.9-498.9-661.9-699.1-763.6-620.5-603.5-535.4-522.5-496.3-338.7-380.2-260.6-2.6-32.8
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-6.4-7.8-10.3-15.0-17.7-24.3-14.6-18.8-16.2-14.6-17.2-14.6-14.4-10.9-13.4-12.0-16.9-18.8-20.9-16.6-16.5-14.7-14.2-13.4-9.1-11.8-7.9-0.1-2.0
Percentage of Assets-1.9-2.2-2.9-4.0-4.6-5.9-3.9-4.8-4.2-3.9-4.8-4.2-4.0-3.1-4.3-3.9-5.3-5.9-6.6-5.5-5.3-5.0-4.8-4.7-3.2-3.9-2.6-0.0-0.6
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-31
Value58874404426441324051390938253697365636063541351634463405338833663323328032653239319132023209319330912722264913581055
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest70.565.068.471.073.277.173.475.373.972.777.576.276.474.381.480.785.088.089.386.687.387.787.086.183.384.680.264.263.1
Percentage of Assets21.218.019.118.919.018.819.519.319.019.421.721.821.221.126.326.326.427.828.428.928.029.929.430.428.928.026.519.819.7
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-31
Value206195193192191189188186186185184183182182181180180179178177177177176176174166164133125
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest2.52.93.13.33.53.73.63.83.83.74.04.04.04.04.34.34.64.84.94.84.84.84.84.84.75.25.06.37.5
Percentage of Assets0.70.80.90.90.90.91.01.01.01.01.11.11.11.11.41.41.41.51.61.61.61.71.61.71.61.71.61.92.3
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-31
Value4148464645406068687770686969596265645954555549557374752914
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.50.70.70.80.80.81.21.41.41.61.51.51.51.51.41.51.71.71.61.51.51.51.41.52.02.32.31.40.8
Percentage of Assets0.10.20.20.20.20.20.30.40.40.40.40.40.40.40.50.50.50.60.50.50.50.50.50.50.70.80.80.40.3
Percentage of Assets us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-31
Value27492658237123172228216119011884183918101558151714661426109510621002901916889835753774778710636676596510
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest32.939.238.139.840.342.636.538.437.236.534.132.932.531.126.325.525.624.225.123.822.820.621.021.019.219.820.528.230.5
Percentage of Assets9.910.910.610.610.510.49.79.89.69.79.59.49.08.88.58.38.07.78.07.97.37.07.17.46.66.56.88.79.5
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value206195193192191189188186186185184183182182181180180179178177177177176176174166164161159135133131127126125124121118114112112110108102
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.80.90.90.90.91.01.01.01.01.11.11.11.11.41.41.41.51.61.61.61.71.61.71.61.71.61.61.61.91.92.22.32.42.32.52.42.62.62.72.43.03.03.2

Additional Paid In Capital Common Stock

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:AdditionalPaidInCapitalCommonStock


Additional
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value588744044264413240513909382536973656360635413516344634053388336633233280326532393191320232093193309127222649249423881405135812591092108610551017899803693638615563507349
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets21.218.019.118.919.018.819.519.319.019.421.721.821.221.126.326.326.427.828.428.928.029.929.430.428.928.026.525.023.819.319.821.119.620.819.720.317.517.515.515.013.415.314.110.7

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value27492658237123172228216119011884183918101558151714661426109510621002901916889835753774778710636676683648596596583554506510519500470482480471466488450
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets9.910.910.610.610.510.49.79.89.69.79.59.49.08.88.58.38.07.78.07.97.37.07.17.46.66.56.86.86.58.28.79.810.09.79.510.49.810.210.811.310.312.613.613.9

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value-530.5-527.8-643.6-870.4-982.2-1231.1-759.6-925.1-802.5-721.5-785.6-673.4-651.4-499.5-559.9-498.9-661.9-699.1-763.6-620.5-603.5-535.4-522.5-496.3-338.7-380.2-260.6-83.7546.9-2.6-41.8-72.6-55.0-32.8-25.8-48.1-36.0-47.2-12.13.76.52.2-9.0
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-1.9-2.2-2.9-4.0-4.6-5.9-3.9-4.8-4.2-3.9-4.8-4.2-4.0-3.1-4.3-3.9-5.3-5.9-6.6-5.5-5.3-5.0-4.8-4.7-3.2-3.9-2.6-0.80.50.1-0.0-0.7-1.3-1.1-0.6-0.5-0.9-0.8-1.1-0.30.10.20.1-0.3

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-31
Value-55.0-55.1-56.1-54.9-55.3-55.3-56.5-57.8-58.8-59.6-61.2-48.7-49.4-43.9-43.0-43.6-44.7-46.1-47.3-38.5-39.3-42.1-42.9-42.9-43.5-43.5-44.2-24.2-24.7-25.4-25.6-52.4-49.0-18.4
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax10.410.48.76.35.64.57.46.27.38.37.87.27.68.87.78.76.86.66.26.26.57.98.28.612.811.417.028.9-45.6-368.1984.6159.8103.8-836.4
Percentage of Assets-0.2-0.2-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.4-0.3-0.3-0.3-0.3-0.3-0.4-0.4-0.4-0.3-0.3-0.4-0.4-0.4-0.4-0.4-0.4-0.2-0.2-0.3-0.4-1.0-1.1-0.5
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedGainLossNetCashFlowHedgeParent


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-31
Value-72.8-39.6-96.4-112.0-121.5-119.7-28.3-63.4-38.5-17.4-5.4107.78.9-7.1
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax13.77.515.012.912.49.73.76.94.82.40.7-1.5-1.2-1.60.9
Percentage of Assets-0.3-0.2-0.4-0.5-0.6-0.6-0.1-0.3-0.2-0.1-0.00.10.00.1-0.1
Percentage of Assets us-gaap:AccumulatedGainLossNetCashFlowHedgeParent0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncome


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-31
Value-530.5-527.8-643.6-870.4-982.2-1231.1-759.6-925.1-802.5-721.5-785.6-673.4-651.4-499.5-559.9-498.9-661.9-699.1-763.6-620.5-603.5-535.4-522.5-496.3-338.7-380.2-260.6-83.7546.9-2.6-32.8-47.22.2
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-1.9-2.2-2.9-4.0-4.6-5.9-3.9-4.8-4.2-3.9-4.8-4.2-4.0-3.1-4.3-3.9-5.3-5.9-6.6-5.5-5.3-5.0-4.8-4.7-3.2-3.9-2.6-0.80.50.1-0.0-0.6-1.10.1
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-31
Value-402.7-433.1-491.1-703.5-805.4-1056.1-674.8-803.9-705.2-644.5-719.0-634.9-609.7-459.0-525.8-459.9-618.9-652.4-709.2-568.8-549.2-490.1-477.4-454.2-301.5-336.6-216.3-59.9763022204.420
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax75.982.176.380.882.085.888.886.987.989.391.594.393.691.993.992.293.593.392.991.791.091.591.491.589.088.583.071.6141.3447.8-850.0-62.5-9.3931.8
Percentage of Assets-1.4-1.8-2.2-3.2-3.8-5.1-3.4-4.2-3.7-3.5-4.4-3.9-3.8-2.8-4.1-3.6-4.9-5.5-6.2-5.1-4.8-4.6-4.4-4.3-2.8-3.5-2.2-0.60.80.40.30.40.10.6
Percentage of Assets us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Minority Interest

us-gaap:MinorityInterest

us-gaap:MinorityInterest


Minority
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value414846464540606868777068696959626564595455554955737475
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.20.20.20.20.20.30.40.40.40.40.40.40.40.50.50.50.60.50.50.50.50.50.50.70.80.8

Stock Issued During Period Value New Issues

us-gaap:StockIssuedDuringPeriodValueNewIssues

us-gaap:StockIssuedDuringPeriodValueNewIssues


Stock
Period End2021-06-302014-12-312014-09-302014-04-16
Value14370.00.0911
Percentage of StockIssuedDuringPeriodValueNewIssues100.00.00.0100.0
Percentage of Assets0.00.00.00.0

us-gaap:StockIssuedDuringPeriodValueNewIssues us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-302014-12-312014-09-30
Value14270.00.0
Percentage of StockIssuedDuringPeriodValueNewIssues99.30.00.0
Percentage of Assets0.00.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.0

us-gaap:CommonStock


Stock
Period End2021-06-302014-12-312014-09-30
Value100.00.0
Percentage of StockIssuedDuringPeriodValueNewIssues0.70.00.0
Percentage of Assets0.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.0

Minority Interest Decrease From Distributions To Noncontrolling Interest Holders

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders


Minority
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value7.410106.3188.5131110108.28.79.88.97.68.110.07.87.48.9
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Minority
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value7.410106.3188.5131110108.28.79.88.97.68.110.07.87.48.9
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value402286364585693108350349515-96.2260191530-217.62613322613076712042251163116110-47.610184104-7.319122863.5
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.813.221.431.743.85.820.319.131.1-4.815.710.832.0-11.816.320.92.111.18.38.024.52.97.624.317.917.0-8.717.515.019.2-1.64.226.518.70.7

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-184200000.0-417900000.0-254000000.0-23000000.0-34800000.0-105000000.0-396200000.0-247600000.0-591500000.0-141300000.0-256500000.0-208100000.0-358800000.0-86900000.0-108800000.0-118800000.0-449300000.0-1416900000.0-44500000.0-421200000.0-265200000.0-132500000.0-32800000.0-227800000.0-72100000.0-70800000.0-11500000.0-44600000.0-42700000.0-192700000.0-27300000.0-42500000.0-24400000.0-27400000.02600000.0
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-9.5-19.3-14.9-1.2-2.2-5.6-23.0-13.6-35.7-7.1-15.5-11.7-21.6-4.7-6.8-7.5-34.9-120.1-4.9-47.3-31.7-17.0-4.9-33.8-11.1-10.9-2.1-7.7-7.6-35.3-6.1-9.3-5.3-6.00.5

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2782-118.1-123.9-128.7-400.41479.78.61125075.2-44.813269-1.2-165.6-255.31501409361104129-92.261-25.3-59.569-6.7-63.718118-23.4-32.1-55.815
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax143.9-5.5-7.3-7.0-25.37.90.60.56.825.50.3-2.58.03.8-0.1-10.4-19.8127.344.840.612.516.6-13.79.1-3.9-9.212.7-1.2-11.33.326.4-5.1-6.9-12.13.1

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

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value3014-213.4994723699.316605.8304-23.7-84.2236-196.3124111246-115.6
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax155.9-9.95.825.523.30.51.03.30.315.3-1.4-4.714.2-10.77.87.016.6-7.0

Increase Decrease In Other Operating Capital Net

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-17.07120-26.1-34.911-3.5-32.427159.1-52.85312-0.5-6.8-9.628-19.3-14.05017-1.940282159-28.48649-22.03.3-0.1213.71.00.029127.7-4.011-21.83.60.210
Percentage of IncreaseDecreaseInOtherOperatingCapitalNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value402286364585693108350349515-96.2260191530-217.62613322613076712042251163116110-47.610184104-7.319122863.5
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.813.221.431.743.85.820.319.131.1-4.815.710.832.0-11.816.320.92.111.18.38.024.52.97.624.317.917.0-8.717.515.019.2-1.64.226.518.70.7

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value19038214217615334698126110334117127114273105130171559512215046621331392151931094960749340336171284046411554464429
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.817.68.39.69.718.55.76.96.616.87.17.26.914.96.68.211.53.46.98.310.53.64.79.210.21.84.17.39.25.46.78.912.06.05.09.511.05.17.08.37.63.411.910.09.66.1

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value201393153187161355105137121351127138123286113118180671011301555768140147325410111357
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.418.29.010.210.219.06.17.57.317.77.77.87.515.67.17.412.14.17.38.810.94.55.19.710.82.64.47.99.66.3

us-gaap:ProfitLoss us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Profit
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1111118.19.111111710108.8128.17.48.5125.97.65.7115.97.68.310
Percentage of ProfitLoss5.72.96.05.02.68.09.35.08.27.87.14.37.26.34.717.85.85.83.719.78.75.45.632.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.50.60.50.50.60.70.90.60.60.50.70.50.50.60.70.40.50.40.90.40.50.60.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Profit
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value1903821761533461261103341171271142731051301715595122150466213313921
Percentage of ProfitLoss94.397.194.095.097.492.090.795.091.892.292.995.792.8110.495.382.294.294.296.380.391.394.694.467.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.817.69.69.718.56.96.616.87.17.26.914.96.68.211.53.46.98.310.53.64.79.210.21.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Share Based Compensation

us-gaap:ShareBasedCompensation

us-gaap:ShareBasedCompensation


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value4.4999999999999993.73.53.43.43.33.53.43.53.63.63.71.64.84.44.44.44.13.83.83.83.33.03.12.92.22.82.72.72.42.32.22.30.92.02.22.31.02.92.68.00.82.32.82.91.0
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-184200000.0-417900000.0-254000000.0-23000000.0-34800000.0-105000000.0-396200000.0-247600000.0-591500000.0-141300000.0-256500000.0-208100000.0-358800000.0-86900000.0-108800000.0-118800000.0-449300000.0-1416900000.0-44500000.0-421200000.0-265200000.0-132500000.0-32800000.0-227800000.0-72100000.0-70800000.0-11500000.0-44600000.0-42700000.0-192700000.0-27300000.0-42500000.0-24400000.0-27400000.02600000.0
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-9.5-19.3-14.9-1.2-2.2-5.6-23.0-13.6-35.7-7.1-15.5-11.7-21.6-4.7-6.8-7.5-34.9-120.1-4.9-47.3-31.7-17.0-4.9-33.8-11.1-10.9-2.1-7.7-7.6-35.3-6.1-9.3-5.3-6.00.5

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2782-118.1-123.9-128.7-400.41479.78.61125075.2-44.813269-1.2-165.6-255.31501409361104129-92.261-25.3-59.569-6.7-63.718118-23.4-32.1-55.815
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax143.9-5.5-7.3-7.0-25.37.90.60.56.825.50.3-2.58.03.8-0.1-10.4-19.8127.344.840.612.516.6-13.79.1-3.9-9.212.7-1.2-11.33.326.4-5.1-6.9-12.13.1

Proceeds From Issuance Of Long Term Debt

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:ProceedsFromIssuanceOfLongTermDebt


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312017-09-302016-12-312016-09-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302012-12-312011-12-31
Value156125-49.7-50.2-50.25750.00.0125600-50.00.0300981000.00.0-100.07006000.00.00.00.0
Percentage of ProceedsFromIssuanceOfLongTermDebt100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.00.0100.0100.0100.00.00.0100.0100.0100.00.00.00.00.0

Payments Of Dividends Common Stock

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:PaymentsOfDividendsCommonStock


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value105978786868781808079757574767170707167676768656762625858564946454544844139383737363433333332
Percentage of PaymentsOfDividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value8.18.47.58.08.59.07.98.48.79.38.89.19.69.810101111101010118.88.99.19.78.48.69.09.78.38.58.89.79.09.81010101111121313
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber us-gaap:PlanName

ajg:LongTermIncentivePlan


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value1.81.82.32.22.22.22.82.82.82.83.33.33.53.54.04.04.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber22.221.430.727.525.924.435.433.332.230.137.536.336.535.737.737.436.4

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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value79.5978.4865.0963.8263.1262.3256.455.9255.5554.9250.1649.9349.4949.3644.9544.8344.6244.3541.441.1840.7940.4239.2539.1638.938.1335.4935.3135.034.5731.3531.2931.1230.7728.828.6228.528.3727.227.1627.1426.7126.2626.2
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

ajg:Range01


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value43.7143.7143.7143.7143.7143.7139.1739.1739.1739.1738.238.0837.9237.8936.1836.1235.9135.6831.5431.3630.9930.7130.5730.5127.2427.2225.7825.8125.8125.8425.8625.8724.8324.4424.2424.2524.1924.02
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice54.955.767.268.569.270.169.570.070.571.376.276.376.676.880.580.680.580.576.276.276.076.077.977.970.071.472.673.173.774.782.582.779.879.484.284.784.984.7

ajg:Range02


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value46.1746.1746.3346.4146.4346.4343.7143.7143.7143.7143.7143.7143.7143.7143.7144.7744.7744.7739.1539.1539.1539.1542.9342.9337.6437.6133.1833.0432.6529.7929.7429.7327.5627.4927.026.9426.9326.93
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice58.058.871.272.773.674.577.578.278.779.687.187.588.388.697.299.9100.3100.994.695.196.096.9109.4109.696.898.693.593.693.386.294.995.088.689.393.894.194.594.9

ajg:Range03


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value56.8356.8356.8356.8356.8356.8146.4346.4646.4746.4746.4846.4946.4946.4946.5146.9446.9446.8943.7143.7143.7143.7146.8746.8746.1746.1739.1939.1539.1535.6235.4335.430.0430.0329.1229.129.129.1
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice71.472.487.389.090.091.282.383.183.784.692.793.193.994.2103.5104.7105.2105.7105.6106.1107.2108.1119.4119.7118.7121.1110.4110.9111.9103.0113.0113.196.597.6101.1101.7102.1102.6

ajg:Range04


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value70.7470.7470.7470.7470.7470.7456.8156.8156.8356.8156.8156.8156.856.856.7856.8656.8656.8646.5346.5346.5346.5347.9247.9246.8846.8746.8746.8746.1639.1735.9535.9535.3835.3533.5133.4431.2433.39
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice88.990.1108.7110.8112.1113.5100.7101.6102.3103.4113.3113.8114.8115.1126.3126.8127.4128.2112.4113.0114.1115.1122.1122.4120.5122.9132.1132.7131.9113.3114.7114.9113.7114.9116.4116.8109.6117.7

ajg:Range05


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-06-302012-03-31
Value79.5979.5979.5979.5979.5979.5970.7470.7470.7470.7470.7470.7470.7470.7446.8746.8739.1739.1739.1739.1728.835.7135.86
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0101.4122.3124.7126.1127.7125.4126.5127.3128.8141.0141.7142.9143.3133.9135.6124.9125.2125.9127.3100.0125.3126.4

ajg:Range06


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312014-03-312013-12-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-31
Value86.1786.1786.1786.1786.1786.1779.5979.5979.5979.5934.5731.3531.2931.1230.7728.6228.528.37
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice108.3109.8132.4135.0136.5138.3141.1142.3143.3144.9100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod us-gaap:PlanName

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod

ajg:LongTermIncentivePlan


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value01800000.0100000.0002200000.00002800000.00-200000.003500000.0003600000.0400000.00001000000.00-500000.002000000.0001800000.0200000.0000500000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod0.0100.0100.00.00.0100.00.00.00.0100.00.0100.00.0100.00.00.0100.0100.00.00.00.0100.00.0100.00.0100.00.00.0100.0100.00.00.00.0100.0

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value49549044533237135237820916311582
Percentage of DeferredTaxLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilities us-gaap:BalanceSheetLocation

ajg:NoncurrentLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value106127106332371347374204158
Percentage of DeferredTaxLiabilities21.626.024.0100.0100.098.798.997.696.8

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsNet


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value147313091144905796643494364320306293
Percentage of DeferredTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Unrecognized Tax Benefits

us-gaap:UnrecognizedTaxBenefits

us-gaap:UnrecognizedTaxBenefits


Unrecognized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value111110101415129.26.75.87.945
Percentage of UnrecognizedTaxBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Valuation Allowance

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:DeferredTaxAssetsValuationAllowance


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value948067796652758.87.47.76.4
Percentage of DeferredTaxAssetsValuationAllowance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:AdjustmentsToAdditionalPaidInCapitalOtherCompensationExpense

ajg:AdjustmentsToAdditionalPaidInCapitalOtherCompensationExpense


Adjustments
Period End2021-06-30
Value300000.0
Percentage of AdjustmentsToAdditionalPaidInCapitalOtherCompensationExpense100.0

ajg:AdjustmentsToAdditionalPaidInCapitalOtherCompensationExpense us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Adjustments
Period End2021-06-30
Value300000.0
Percentage of AdjustmentsToAdditionalPaidInCapitalOtherCompensationExpense100.0

ajg:AmortizationOfDeferredCompensationAndRestrictedStock

ajg:AmortizationOfDeferredCompensationAndRestrictedStock


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value17141514151512121210.09.99.8129.98.18.5106.26.97.08.95.75.95.57.14.25.66.16.44.88.44.93.52.21.92.02.71.71.51.52.21.61.81.51.91.4
Percentage of AmortizationOfDeferredCompensationAndRestrictedStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitments

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitments


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value-0.117-0.2-1.80.621-4.22.9-0.1190.51.2-0.819-3.5-0.3-0.323-12.0-11.41337-77.995-5.950-33.8-373.441834
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitments us-gaap:GuaranteeObligationsByNature

us-gaap:FinancialGuarantee


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.01.10.00.00.01.20.0-0.1-0.11.60.0-0.1-0.11.80.00.1-0.32.3-0.1-1.8-0.14.4-13.7-1.0-0.419-0.5120.09.1
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitments-0.06.3-0.0-0.00.05.7-0.0-3.4100.08.00.0-8.312.59.5-0.0-33.3100.09.70.815.8-0.811.917.6-1.06.839.11.5-3.20.026.1

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitments us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

ajg:LettersOfCredit


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value0.0150.00.10.018-0.7-0.50.0180.51.3-0.717-3.5-0.40.0210.00.0-0.421-1.60.50.0222.0-0.50.0210.8-0.70.0150.00.00.015-0.60.0
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitments-0.087.4-0.0-5.60.087.116.7-17.2-0.092.0100.0108.387.590.5100.0133.3-0.088.7-0.0-0.0-3.058.02.10.5-0.044.4-5.90.10.060.60.00.00.00.00.00.00.00.00.00.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitments us-gaap:OtherCommitments

ajg:FundingCommitments


Amount
Period End2021-06-302021-03-312020-09-302020-06-302020-03-31
Value-0.11.1-1.90.61.5
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitments100.06.3105.6100.07.1

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFive

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFive


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0200000.0000200000.0000200000.0000200000.0000200000.00-200000.00400000.0-1900000.001500000.0800000.0900000.00
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFive0.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.0100.00.0100.0100.00.0100.0100.0100.00.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFive us-gaap:GuaranteeObligationsByNature

us-gaap:FinancialGuarantee


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0200000.0000200000.0000200000.0000200000.0000200000.00-200000.00400000.0-400000.000800000.0900000.00
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFive0.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.0100.00.0100.021.10.00.0100.0100.00.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFour

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFour


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0200000.0000200000.0000200000.0000200000.0000200000.0-1300000.01100000.00400000.01200000.0-100000.00800000.0800000.00
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFour0.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.00.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFour us-gaap:GuaranteeObligationsByNature

us-gaap:FinancialGuarantee


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0200000.0000200000.0000200000.0000200000.0000200000.00-200000.00400000.0-300000.0-100000.00800000.0800000.00
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearFour0.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.0-0.0-18.20.0100.0-25.0100.00.0100.0100.00.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearOne

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearOne


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value-0.11.20.0-2.00.61.6-3.33.4-1.41.5-0.80.91.3-0.10.00.1-9.7-5.19.08.7-36.251-5.56.2-34.5-384.94181.7
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearOne100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearOne us-gaap:GuaranteeObligationsByNature

us-gaap:FinancialGuarantee


Amount
Period End2021-06-302021-03-312020-06-302020-03-312019-06-302019-03-312018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0.00.10.00.1-0.10.2-0.10.20.2-0.10.00.1-0.20.4-0.30.00.00.70.80.0
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearOne-0.08.30.06.27.113.312.522.215.4100.00.0100.0-2.24.60.80.0-0.011.3-2.3-0.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearOne us-gaap:OtherCommitments

ajg:FundingCommitments


Amount
Period End2021-06-302021-03-312020-09-302020-06-302020-03-31
Value-0.11.1-1.90.61.5
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearOne100.091.795.0100.093.8

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThereafter

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThereafter


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.015-0.20.20.018-0.9-0.51.317-1.01.30.017-4.8-0.2-0.322-0.50.1-0.323-13.7-0.2-1.941-2.6110.033
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThereafter0.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThereafter us-gaap:GuaranteeObligationsByNature

us-gaap:FinancialGuarantee


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.00.2-0.20.10.00.3-0.20.00.00.6-0.20.00.00.8-0.20.2-0.31.4-0.3-0.80.12.4-12.1-0.7-0.416-4.6120.09.1
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThereafter0.01.3100.050.00.01.622.2-0.00.03.420.00.00.04.64.2-100.0100.06.160.0-800.0-33.310.088.3350.021.138.6176.9104.30.027.5

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThereafter us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

ajg:LettersOfCredit


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value0.0150.00.10.018-0.7-0.51.317-0.81.30.016-4.2-0.40.0210.00.0-0.421-1.60.50.0222.0-0.50.0210.8-0.70.0150.00.00.015-0.60.0
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThereafter0.098.7-0.050.00.098.477.8100.0100.096.680.0100.00.095.487.5200.0-0.092.1-0.00.0133.390.011.7-250.0-0.054.5-76.9-4.30.063.70.00.00.00.00.00.00.00.00.00.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThree

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThree


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0200000.0000200000.0000200000.0000200000.0000200000.00-200000.0-200000.0600000.0-3000000.02600000.00800000.0800000.00
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThree0.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.0100.0100.0100.0100.0100.00.0100.0100.00.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThree us-gaap:GuaranteeObligationsByNature

us-gaap:FinancialGuarantee


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0200000.0000200000.0000200000.0000200000.0000200000.00-200000.0-200000.0600000.0-300000.0-100000.00800000.0800000.00
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearThree0.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.0100.0100.0100.010.0-3.80.0100.0100.00.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearTwo

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearTwo


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0.00.20.00.00.00.20.00.00.00.21.30.00.00.20.00.00.00.2-0.5-7.14.73.1-24.3410.00.80.80.0
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearTwo0.0100.00.00.00.0100.00.00.00.0100.0100.00.00.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.00.0

ajg:AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearTwo us-gaap:GuaranteeObligationsByNature

us-gaap:FinancialGuarantee


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0.00.20.00.00.00.20.00.00.00.20.00.00.00.20.00.00.00.20.0-0.20.20.2-0.3-0.10.00.80.80.0
Percentage of AmountOfCommitmentExpirationOffBalanceSheetCommitmentsWithinYearTwo0.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.0-0.02.84.36.51.2-0.20.0100.0100.00.0

ajg:AmountOfGainLossRecognizedEffectivenessTesting

ajg:AmountOfGainLossRecognizedEffectivenessTesting


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value300000.0600000.0900000.0700000.0500000.0200000.0200000.0300000.0400000.0400000.0
Percentage of AmountOfGainLossRecognizedEffectivenessTesting100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:AmountOfGainLossRecognizedEffectivenessTesting us-gaap:DerivativeInstrumentRisk, us-gaap:IncomeStatementLocation

us-gaap:ForeignExchangeContract, ajg:CommissionRevenue


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-100000.0-100000.00-100000.0-100000.0-200000.0-200000.0-200000.0-200000.0-200000.0
Percentage of AmountOfGainLossRecognizedEffectivenessTesting-33.3-16.70.0-14.3-20.0-100.0-100.0-66.7-50.0-50.0

ajg:AmountOfGainLossRecognizedEffectivenessTesting us-gaap:IncomeStatementLocation

ajg:CompensationExpense


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value200000.0400000.0600000.0400000.0400000.0200000.0200000.0300000.0300000.0400000.0
Percentage of AmountOfGainLossRecognizedEffectivenessTesting66.766.766.757.180.0100.0100.0100.075.0100.0

us-gaap:OperatingExpense


Amount
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value200000.0300000.0300000.0400000.0200000.0200000.0200000.0200000.0300000.0200000.0
Percentage of AmountOfGainLossRecognizedEffectivenessTesting66.750.033.357.140.0100.0100.066.775.050.0

ajg:BusinessAcquisitionsProFormaNetIncomeLossToControllingInterest

ajg:BusinessAcquisitionsProFormaNetIncomeLossToControllingInterest


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value19038214017615334610212710933412212711627310611317255991221494666134139225596
Percentage of BusinessAcquisitionsProFormaNetIncomeLossToControllingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:BusinessCombinationAggregateEarnoutObligationMaximum

ajg:BusinessCombinationAggregateEarnoutObligationMaximum


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-312018-09-302018-06-302016-12-312016-09-302016-06-302012-12-312012-09-302012-06-302011-09-30
Value-78.000000000000111146102-34.60000000000012-69.911302183262495552235035017031428920
Percentage of BusinessCombinationAggregateEarnoutObligationMaximum100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:BusinessCombinationAnnualizeRevenue us-gaap:BusinessAcquisition

ajg:BusinessCombinationAnnualizeRevenue

ajg:BusinessAcquisition


Business
Period End2021-06-302021-03-312015-09-30
Value7010361
Percentage of BusinessCombinationAnnualizeRevenue100.0100.0100.0

ajg:CashAndEquityAwardWithAggregateFairValueVestedAndDistributedToParticipants us-gaap:AwardType

ajg:CashAndEquityAwardWithAggregateFairValueVestedAndDistributedToParticipants

ajg:DeferredCashParticipationPlan


Cash
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value-4.10.07.30.00.00.01.70.83.60.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of CashAndEquityAwardWithAggregateFairValueVestedAndDistributedToParticipants100.00.0100.00.00.00.0100.0100.0100.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

ajg:DeferredEquityParticipationPlan


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2.42.4310.07.52.30.01.81.30.06.40.00.08.40.00.00.00.60.41.74.9
Percentage of CashAndEquityAwardWithAggregateFairValueVestedAndDistributedToParticipants0.00.0-765.90.0102.70.00.00.076.50.0177.80.00.00.00.00.00.00.00.00.00.0

ajg:CashBasedCompensationAwardExpenses us-gaap:AwardType

ajg:CashBasedCompensationAwardExpenses

ajg:RestrictedStockUnitProvisionalCashAwards


Cash
Period End2020-09-302019-09-30
Value3.32.5
Percentage of CashBasedCompensationAwardExpenses100.0100.0

ajg:TwoThousandEighteenProvisionalCashAwards


Cash
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-03-31
Value0.0172.70.92.62.52.21.90.0
Percentage of CashBasedCompensationAwardExpenses0.00.081.80.00.0100.00.00.00.0

ajg:TwoThousandNineteenProvisionalCashAwards


Cash
Period End2021-06-302020-06-302019-12-312019-09-302019-06-302019-03-31
Value1.91.92.32.52.21.9
Percentage of CashBasedCompensationAwardExpenses0.00.00.0100.00.00.0

ajg:TwoThousandSeventeenProvisionalCashAwards


Cash
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312017-03-16
Value0.00.0182.62.72.62.42.42.41.92.00.00.00.00.00.0
Percentage of CashBasedCompensationAwardExpenses0.00.00.00.0108.00.00.00.00.00.00.00.00.00.00.00.0

ajg:TwoThousandTwentyProvisionalCashAwards


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-09-30
Value2.32.93.42.91.92.22.9
Percentage of CashBasedCompensationAwardExpenses0.00.00.087.90.00.0116.0

ajg:ChangeInEstimatedAcquisitionEarnoutPayables

ajg:ChangeInEstimatedAcquisitionEarnoutPayables


Change
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1315202015-89.03.35.73.42.92.45.8-6.07.43.4105.111104.1133.9149.75.6100.94.57.05.10.2-0.4-2.54.42.43.7-5.22.5-0.2-4.3-2.50.80.3-3.9-0.91.9
Percentage of ChangeInEstimatedAcquisitionEarnoutPayables100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:CompensationApprovedByCommitteeValue us-gaap:AwardType

ajg:CompensationApprovedByCommitteeValue

ajg:DeferredCashParticipationPlan


Compensation
Period End2021-03-312020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-06-302017-03-312016-06-302016-03-312015-03-312014-03-312013-03-31
Value7.23.02.42.42.45.65.65.65.15.13.13.12.72.92.7
Percentage of CompensationApprovedByCommitteeValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:DeferredEquityParticipationPlan


Compensation
Period End2021-03-312020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-03-312015-03-312014-03-31
Value1714101010110.00.011140.00.01410108.99.2
Percentage of CompensationApprovedByCommitteeValue236.1470.0420.8420.8420.80.00.00.0205.40.00.00.0274.50.0325.8329.6317.2

ajg:DeferredEquityParticipationPlanSubPlans


Compensation
Period End2021-03-312020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-06-30
Value3.21.82.62.62.60.00.00.90.00.04.013
Percentage of CompensationApprovedByCommitteeValue44.460.0108.3108.3108.30.00.016.10.00.078.4438.7

ajg:ContractWithCustomerImpactOfChangeInForeignExchangeRates

ajg:ContractWithCustomerImpactOfChangeInForeignExchangeRates


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value1.44.4124.3-23.317
Percentage of ContractWithCustomerImpactOfChangeInForeignExchangeRates100.0100.0100.0100.0100.0100.0

ajg:ContractWithCustomerImpactOfChangeInForeignExchangeRates us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value1.40000000000000044.1104.5-23.317
Percentage of ContractWithCustomerImpactOfChangeInForeignExchangeRates100.093.285.2104.7100.0100.0

ajg:RiskManagementSegment


Contract
Period End2021-06-302021-03-312020-12-31
Value0.00.31.8
Percentage of ContractWithCustomerImpactOfChangeInForeignExchangeRates0.06.814.8

ajg:ContractWithCustomerLiabilityAdditions

ajg:ContractWithCustomerLiabilityAdditions


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value92214614.7992086437106204
Percentage of ContractWithCustomerLiabilityAdditions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:ContractWithCustomerLiabilityAdditions us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value67188381464166374.971162
Percentage of ContractWithCustomerLiabilityAdditions73.387.762.1300.064.779.757.313.266.979.6

ajg:RiskManagementSegment


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value242623-9.4354227323541
Percentage of ContractWithCustomerLiabilityAdditions26.712.337.9-200.035.320.342.786.833.120.4

ajg:CostReimbursements

ajg:CostReimbursements


Cost
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value363240413237373433333437353433333533
Percentage of CostReimbursements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:DeferredCompensationAndRestrictedStockExpensesBenefit

ajg:DeferredCompensationAndRestrictedStockExpensesBenefit


Deferred
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-12.237-14.65.215114.2-7.59.38.612-14.18.18.410-22.36.46.8-4.9-8.2
Percentage of DeferredCompensationAndRestrictedStockExpensesBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:DeferredCompensationAndRestrictedStockExpensesBenefit us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Deferred
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-12.138-14.65.315114.1-7.59.38.512-14.38.18.410-22.56.46.8-4.9-8.4
Percentage of DeferredCompensationAndRestrictedStockExpensesBenefit99.2100.8100.0101.9102.0100.097.6100.0100.098.8100.0101.4100.0100.099.1100.9100.0100.0100.0102.4

us-gaap:CommonStock


Deferred
Period End2021-06-302021-03-312020-06-302020-03-312019-06-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-0.1-0.3-0.1-0.30.10.00.10.00.20.00.00.10.20.00.00.00.2
Percentage of DeferredCompensationAndRestrictedStockExpensesBenefit0.8-0.8-1.9-2.02.40.01.20.0-1.40.00.00.9-0.90.00.0-0.0-2.4

ajg:DeferredCompensationAndRestrictedStockInShares us-gaap:StatementEquityComponents

ajg:DeferredCompensationAndRestrictedStockInShares

us-gaap:CommonStock


Deferred
Period End2021-06-302021-03-312020-06-302020-03-312019-06-302018-09-302018-03-31
Value100000.0300000.0-100000.0-300000.0100000.0100000.0200000.0
Percentage of DeferredCompensationAndRestrictedStockInShares100.0100.0100.0100.0100.0100.0100.0

ajg:DefinedBenefitPlanPercentageOfEligibleCompensationForMatchingContributionsByEmployer us-gaap:RetirementPlanType

ajg:DefinedBenefitPlanPercentageOfEligibleCompensationForMatchingContributionsByEmployer

ajg:QualifiedContributorySavingsAndThriftFourZeroOneKPlan


Defined
Period End2021-06-302021-03-312020-12-31
Value5.05.00
Percentage of DefinedBenefitPlanPercentageOfEligibleCompensationForMatchingContributionsByEmployer100.0100.00.0

ajg:EarnoutPaymentsForAcquisitions

ajg:EarnoutPaymentsForAcquisitions


Earnout
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value97176.21.99.7218.9235.88.25.531159.4114.515103.811227.8
Percentage of EarnoutPaymentsForAcquisitions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:GoodwillWrittenOffRelatedToSaleOfBusinessAndImpairment

ajg:GoodwillWrittenOffRelatedToSaleOfBusinessAndImpairment


Goodwill
Period End2021-06-302021-03-31
Value01000000.0
Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessAndImpairment0.0100.0

ajg:GoodwillWrittenOffRelatedToSaleOfBusinessAndImpairment us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Goodwill
Period End2021-06-302021-03-31
Value01000000.0
Percentage of GoodwillWrittenOffRelatedToSaleOfBusinessAndImpairment0.0100.0

ajg:IncreaseDecreaseInPremiumsAndFeeReceivable

ajg:IncreaseDecreaseInPremiumsAndFeeReceivable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-12.61691-501.4-271.2-486.72055-397.4-276.9-176.612850.8-315.0-408.11505-752.4-734.3
Percentage of IncreaseDecreaseInPremiumsAndFeeReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:MinorityInterestIncreaseDecreaseFromRedemptions

ajg:MinorityInterestIncreaseDecreaseFromRedemptions


Minority
Period End2021-06-302020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value-11000000.0-800000.04300000.0-10800000.0900000.0-7300000.0-300000.0
Percentage of MinorityInterestIncreaseDecreaseFromRedemptions100.0100.0100.0100.0100.0100.0100.0

ajg:MinorityInterestIncreaseDecreaseFromRedemptions us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Minority
Period End2021-06-302020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value-11000000.0-800000.04300000.0-10800000.0900000.0-7300000.0-100000.0
Percentage of MinorityInterestIncreaseDecreaseFromRedemptions100.0100.0100.0100.0100.0100.033.3

ajg:NetBorrowingsOnPremiumFinancingDebtFacility

ajg:NetBorrowingsOnPremiumFinancingDebtFacility


Net
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-0.979-36.2-26.5-4.0385.1-20.513
Percentage of NetBorrowingsOnPremiumFinancingDebtFacility100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:NetBorrowingsPaymentsOnPremiumFinancingDebtFacility

ajg:NetBorrowingsPaymentsOnPremiumFinancingDebtFacility


Net
Period End2021-06-302021-03-312020-06-302020-03-31
Value-16.8543626
Percentage of NetBorrowingsPaymentsOnPremiumFinancingDebtFacility100.0100.0100.0100.0

ajg:NetChangeInAccruedCompensationAndOtherAccruedLiabilities

ajg:NetChangeInAccruedCompensationAndOtherAccruedLiabilities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value209-155.9-98.2-200.0-100.6307-127.9-116.9-41.2209-101.0-79.6-29.7165-100.0-46.3120-43.1-141.2-10.2101-19.0-180.4-27.027-38.1-72.8-58.157-111.113-56.548-41.9-61.8-26.2-22.190-54.6-23.1-8.964-22.4-4.0-28.558
Percentage of NetChangeInAccruedCompensationAndOtherAccruedLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:NetChangeInCollectedBillingsAndDepositsReceivedFromCustomers

ajg:NetChangeInCollectedBillingsAndDepositsReceivedFromCustomers


Net
Period End2021-06-302021-03-312020-12-31
Value-9.60000000000000116-0.7
Percentage of NetChangeInCollectedBillingsAndDepositsReceivedFromCustomers100.0100.0100.0

ajg:NetChangeInCollectedBillingsAndDepositsReceivedFromCustomers us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Net
Period End2021-06-302021-03-312020-12-31
Value-5.85.61.2
Percentage of NetChangeInCollectedBillingsAndDepositsReceivedFromCustomers60.434.8-171.4

ajg:RiskManagementSegment


Net
Period End2021-06-302021-03-312020-12-31
Value-3.810-1.9
Percentage of NetChangeInCollectedBillingsAndDepositsReceivedFromCustomers39.665.2271.4

ajg:NetProceedsFromSalesOfOperations

ajg:NetProceedsFromSalesOfOperations


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value4.15.3-0.80000000000000096.51.41.11.62.33.1741.90.59.92.20.30.31.21.40.54.21.41.70.54.33.60.85.10.40.72.02.20.42.50.42.50.73.54.71.30.8101.1
Percentage of NetProceedsFromSalesOfOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:PaymentsOnSettlementsOfTerminatedInterestRateSwaps

ajg:PaymentsOnSettlementsOfTerminatedInterestRateSwaps


Payments
Period End2020-09-302019-09-30
Value7.450580596923828e-150.0
Percentage of PaymentsOnSettlementsOfTerminatedInterestRateSwaps100.00.0

ajg:PaymentsToAcquireBusinessesNetOfCashAndRestrictedCashAcquired

ajg:PaymentsToAcquireBusinessesNetOfCashAndRestrictedCashAcquired


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1563952338.46.77631521755817520918033857738877137
Percentage of PaymentsToAcquireBusinessesNetOfCashAndRestrictedCashAcquired100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:RecordedEarnOutPayable

ajg:RecordedEarnOutPayable


Recorded
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value29194617101321023796354121171331181732196.3153.1133.329112828176.226172.73.82927
Percentage of RecordedEarnOutPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax

ajg:RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value18962132166318071551182916831790162419571623174116251802148515591454
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, ajg:BrokerFees, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value296333269295
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax15.615.617.316.2

us-gaap:OperatingSegments, ajg:BrokerFees, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value244220190211
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax12.910.312.311.6

us-gaap:OperatingSegments, ajg:Commissions, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value97711258271017
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax51.552.853.355.6

us-gaap:OperatingSegments, ajg:ContingentRevenue, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value43633745
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax2.33.02.42.5

us-gaap:OperatingSegments, ajg:NetGainsOnDivestitures, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value0.54.11.00.2
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax0.00.20.10.0

us-gaap:OperatingSegments, ajg:NetGainsOnDivestitures, ajg:RiskManagementSegment


Revenue
Period End2021-06-30
Value0.1
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax0.0

us-gaap:OperatingSegments, ajg:SupplementalRevenueMember, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value55665059
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax2.93.13.23.2

us-gaap:OperatingSegments, us-gaap:InvestmentPerformance, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value18171518
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax1.00.81.01.0

us-gaap:OperatingSegments, us-gaap:InvestmentPerformance, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value0.00.10.20.3
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax0.00.00.00.0

us-gaap:OperatingSegments, us-gaap:ProductAndServiceOther, us-gaap:Corporate


Revenue
Period End2021-06-302021-03-312020-06-30
Value0.61.50.2
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax0.00.10.0

us-gaap:OperatingSegments, us-gaap:PublicUtilitiesInventoryCoal, us-gaap:Corporate


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value261300159181
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax13.814.110.39.9

ajg:RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, ajg:BrokerageSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value13901610123512941201143511921195113113811001104910001195895938896
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax73.375.574.371.677.478.570.866.869.670.661.760.361.566.360.360.261.6

us-gaap:OperatingSegments, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value245220216202190211214211209203202199201195188190181
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax12.910.313.011.212.311.612.711.812.910.412.511.412.410.812.712.212.5

us-gaap:OperatingSegments, us-gaap:Corporate


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value261302211310159181276383284372419492423412401430376
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax13.814.212.717.210.39.916.421.417.519.025.828.326.022.927.027.625.9

ajg:RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax us-gaap:ProductOrService

ajg:BrokerFees


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value540553459507
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax28.526.029.627.7

ajg:Commissions


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value97711258271017
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax51.552.853.355.6

ajg:ContingentRevenue


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value43633745
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax2.33.02.42.5

ajg:NetGainsOnDivestitures


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value0.64.11.00.2
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax0.00.20.10.0

ajg:SupplementalRevenue


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value55665059
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax2.93.13.23.2

ajg:SupplementalRevenueMember


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value55665059
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax2.93.13.23.2

us-gaap:InvestmentPerformance


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value18171618
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax1.00.81.01.0

us-gaap:ProductAndServiceOther


Revenue
Period End2021-06-302021-03-312020-06-30
Value0.61.50.2
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax0.00.10.0

us-gaap:PublicUtilitiesInventoryCoal


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value261300159181
Percentage of RevenueFromContractWithCustomerBeforeReimbursementsExcludingAssessedTax13.814.110.39.9

ajg:RevenueFromContractWithCustomerExcludingAssessedTaxReimbursements

ajg:RevenueFromContractWithCustomerExcludingAssessedTaxReimbursements


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value36323237
Percentage of RevenueFromContractWithCustomerExcludingAssessedTaxReimbursements100.0100.0100.0100.0

ajg:RevenueFromContractWithCustomerExcludingAssessedTaxReimbursements us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, ajg:RiskManagementSegment


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value36323237
Percentage of RevenueFromContractWithCustomerExcludingAssessedTaxReimbursements100.0100.0100.0100.0

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardAggregateFairValue us-gaap:AwardType

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardAggregateFairValue

us-gaap:PerformanceShares


Share
Period End2021-03-162020-03-122019-03-142018-09-302018-06-302018-03-152018-03-312017-09-302017-06-302017-03-162017-03-312016-03-172016-03-112015-03-112014-03-12
Value8600000.07100000.05800000.0005300000.05300000.0004900000.04900000.03200000.03200000.02500000.02300000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardAggregateFairValue100.0100.0100.00.00.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue us-gaap:AwardType

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue

us-gaap:RestrictedStockUnitsRSU


Share
Period End2021-03-312020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-06-302017-03-312016-03-31
Value4034313131281.3281.22620
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodIntrinsicValue

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodIntrinsicValue


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-30
Value294837212125171220277.0134.1294.45.56.2164.46.96.31.70.73.512103.96.9109.33.25.5
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodIntrinsicValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearOne us-gaap:TitleOfIndividual, us-gaap:PlanName

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearOne

srt:Officer, ajg:LongTermIncentivePlan


Share
Period End2021-03-162020-03-122019-03-142018-03-15
Value34.00.340.340.34
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearOne100.0100.0100.0100.0

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearThree us-gaap:TitleOfIndividual, us-gaap:PlanName

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearThree

srt:Officer, ajg:LongTermIncentivePlan


Share
Period End2021-03-162020-03-122019-03-142018-03-15
Value33.00.330.330.33
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearThree100.0100.0100.0100.0

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearTwo us-gaap:TitleOfIndividual, us-gaap:PlanName

ajg:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearTwo

srt:Officer, ajg:LongTermIncentivePlan


Share
Period End2021-03-162020-03-122019-03-142018-03-15
Value33.00.330.330.33
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodExercisePercentageYearTwo100.0100.0100.0100.0

ajg:UnearnedDeferredCompensationShare us-gaap:AwardType

ajg:UnearnedDeferredCompensationShare

ajg:DeferredEquityParticipationPlan


Unearned
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value0.12.6-0.30.00.02.90.00.00.02.92.85454-0.10.02.62.70.00.3
Percentage of UnearnedDeferredCompensationShare100.0100.0100.00.00.0100.00.00.00.0100.0100.0100.0100.0100.00.0100.0100.00.0100.0

ajg:UnearnedDeferredCompensationValue us-gaap:AwardType

ajg:UnearnedDeferredCompensationValue

ajg:DeferredEquityParticipationPlan


Unearned
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-6.585-4.8-5.4-6.176-4.9-3.64.069606267-3.7-3.82.866-2.9-2.8
Percentage of UnearnedDeferredCompensationValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

ajg:WeightedAverageNumberOfCommonAndCommonEquivalentSharesOutstanding

ajg:WeightedAverageNumberOfCommonAndCommonEquivalentSharesOutstanding


Weighted
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value2051990.51961941930.51901891880.51861851850.51821811800.21781781771.41761711663.31611551351.21311281271.31241211170.81131111100.7105104
Percentage of WeightedAverageNumberOfCommonAndCommonEquivalentSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AdjustmentForAmortization

us-gaap:AdjustmentForAmortization


Adjustment
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value10810596978813593847976767273686569656462636259685859545454423835302929252526212420181615141613
Percentage of AdjustmentForAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts us-gaap:BusinessAcquisition, us-gaap:StatementEquityComponents

us-gaap:AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts

ajg:WillisTowersWatsonPLC, us-gaap:CommonStock


Adjustments
Period End2021-05-17
Value1437
Percentage of AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts100.0

us-gaap:BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued

us-gaap:BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value0.0920.060.6570.2250.3570.6041.1790.0850.0710.4520.0480.5050.2130.060.2730.00.2490.1660.00.4220.9340.4940.1171.8153.3251.0932.1661.7081.350.5151.6733.4-5549.03455511.6771.6660.9720.424
Percentage of BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessAcquisitionProFormaEarningsPerShareBasic

us-gaap:BusinessAcquisitionProFormaEarningsPerShareBasic


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value0.951.960.710.920.811.830.520.680.591.810.670.70.641.510.580.620.960.310.560.690.840.260.370.760.810.130.250.590.710.370.510.570.730.320.310.50.590.240.370.420.360.150.430.460.44
Percentage of BusinessAcquisitionProFormaEarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessAcquisitionProFormaEarningsPerShareDiluted

us-gaap:BusinessAcquisitionProFormaEarningsPerShareDiluted


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value0.931.920.70.90.791.790.510.670.571.770.650.680.631.480.580.620.950.310.560.690.840.260.370.760.80.130.250.580.70.360.50.570.730.320.30.490.590.240.370.420.360.150.430.460.44
Percentage of BusinessAcquisitionProFormaEarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax us-gaap:BusinessAcquisition

us-gaap:BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax

ajg:BusinessAcquisition


Business
Period End2021-06-302021-03-312015-03-312014-12-312014-09-302014-06-302014-03-31
Value1.71.00.31016100.4
Percentage of BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessAcquisitionsProFormaNetIncomeLoss

us-gaap:BusinessAcquisitionsProFormaNetIncomeLoss


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value-4.6-6.0-11.999999999999993-14.2-8.0995.21.42.42.71.91.3102.35805.70.1-6.7-23.90.2-9.20.3106.01.36.4-3.00.63.61.83.03.35.41.5-0.11.37.4-0.12.36.64.41.21.25.62.5
Percentage of BusinessAcquisitionsProFormaNetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessAcquisitionsProFormaRevenue

us-gaap:BusinessAcquisitionsProFormaRevenue


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value193621711793185015861868181318351672199317391780168318391622165015661414142014821429130413771461137912341303129312519161075850779674747653654550434740455484946
Percentage of BusinessAcquisitionsProFormaRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessAcquisitionsProFormaRevenue us-gaap:BusinessAcquisition

ajg:BusinessAcquisition


Business
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value4119106.01407243186961206.2433122143422142.25240215.6167161822.2
Percentage of BusinessAcquisitionsProFormaRevenue2.10.90.70.37.73.92.60.94.03.51.20.32.71.91.41.02.41.51.00.23.82.81.50.512.812.56.60.2

us-gaap:BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable

us-gaap:BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-262018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value136.3702135621076.85.3353.53424123.7150.0138.40.02037174.57714948
Percentage of BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable us-gaap:BusinessAcquisition

ajg:CapsicumReinsuranceBrokersLLP


Business
Period End2020-12-312020-09-302020-06-302020-03-31
Value0.00.00.062
Percentage of BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable0.00.00.0100.0

ajg:FourOtherAcquisitions


Business
Period End2021-03-31
Value6.3
Percentage of BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable100.0

ajg:OtherAcquisition


Business
Period End2020-09-302019-09-302018-12-312018-09-30
Value216.83.510
Percentage of BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable100.0100.0100.029.9

us-gaap:BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1

us-gaap:BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-18600000.0-5700000.00-200000.0-13200000.0-1100000.0-1900000.0-4900000.0-2700000.0-7100000.0-1800000.0
Percentage of BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed

us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed


Business
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value9.29.08.25.97.7108.57.15.85.64.34.54.95.15.04.95.25.14.44.34.04.24.03.74.34.23.93.93.43.33.22.92.92.92.32.42.22.42.12.31.92.01.51.71.6
Percentage of BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination

us-gaap:ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1.57.15.50.42.91.16.34.420-0.4
Percentage of ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1.57.15.50.42.91.16.34.420-0.4
Percentage of ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiabilityRevenueRecognized

us-gaap:ContractWithCustomerLiabilityRevenueRecognized


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value841926823842046151103181
Percentage of ContractWithCustomerLiabilityRevenueRecognized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiabilityRevenueRecognized us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value58167462259154331567137
Percentage of ContractWithCustomerLiabilityRevenueRecognized69.186.967.195.869.875.654.630.365.775.7

ajg:RiskManagementSegment


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value2625221.0255027363544
Percentage of ContractWithCustomerLiabilityRevenueRecognized30.913.132.94.230.224.445.469.734.324.3

us-gaap:DefinedContributionPlanCostRecognized us-gaap:RetirementPlanType

us-gaap:DefinedContributionPlanCostRecognized

ajg:QualifiedContributorySavingsAndThriftFourZeroOneKPlan


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value1717171514151514
Percentage of DefinedContributionPlanCostRecognized100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Depreciation

us-gaap:Depreciation


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value373837363436363535343333303030303029272526242523222119181614151413101010109.79.39.49.18.18.38.38.07.7
Percentage of Depreciation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DepreciationAmortizationAndAccretionNet

us-gaap:DepreciationAmortizationAndAccretionNet


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1451431331331221721291191151101091061049896100959389888884938182767372595250454240363636303329272424222421
Percentage of DepreciationAmortizationAndAccretionNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-2000000.0-1700000.0-2400000.0-1400000.0-1300000.0-1200000.0-2200000.0-1100000.0-1200000.0-700000.01500000.01100000.01300000.01800000.0500000.0-1600000.0-1700000.0-2400000.0-3000000.0-3300000.0-700000.0-1200000.0
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:ForeignExchangeContract, ajg:CommissionRevenue


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-1400000.0-900000.0-1500000.0-400000.0-100000.0-400000.0-1200000.0-200000.0-100000.0-100000.0800000.0400000.0400000.0700000.0-1100000.0-2300000.0-2500000.0-2800000.0-3400000.0-3600000.0-900000.0-1200000.0
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet70.052.962.528.67.733.354.518.28.314.353.336.430.838.9-220.0143.8147.1116.7113.3109.1128.6100.0

us-gaap:InterestRateContract, us-gaap:InterestExpense


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-300000.0-300000.0-200000.0-300000.0-300000.0-300000.0-300000.0-300000.0-300000.0-300000.0300000.0300000.0300000.0200000.0
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet15.017.68.321.423.125.013.627.325.042.920.027.323.111.1

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet us-gaap:IncomeStatementLocation

ajg:CompensationExpense


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-200000.0-300000.0-400000.0-400000.0-500000.0-300000.0-400000.0-400000.0-400000.0-200000.0200000.0200000.0400000.0500000.0700000.0400000.0500000.0200000.0200000.0200000.0
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet10.017.616.728.638.525.018.236.433.328.613.318.230.827.8140.0-25.0-29.4-8.3-6.7-6.1

us-gaap:OperatingExpense


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-100000.0-200000.0-300000.0-300000.0-400000.0-200000.0-300000.0-200000.0-400000.0-100000.0200000.0200000.0200000.0400000.0500000.0300000.0300000.0200000.0100000.0100000.0
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet5.011.812.521.430.816.713.618.233.314.313.318.215.422.2100.0-18.8-17.6-8.3-3.3-3.0

us-gaap:DividendsCommonStockCash

us-gaap:DividendsCommonStockCash


Dividends
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value1009487868681818076767575717170706868686766656461595857484646454442206-122.54038373736
Percentage of DividendsCommonStockCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStockCash us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value1009487868681818076767575717170706868686766656461595857484646454442206-122.54038373736
Percentage of DividendsCommonStockCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Effect
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value38111-142.253-49.8-31.234-32.9-22.6-68.238-26.5631519
Percentage of EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations


Effect
Period End2021-06-302021-03-312020-06-302020-03-31
Value1336111-142.2
Percentage of EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations100.0100.0100.0100.0

us-gaap:ForeignCurrencyTransactionGainLossUnrealized

us-gaap:ForeignCurrencyTransactionGainLossUnrealized


Foreign
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value-1.7-4.8-5.9-3.5-5.912-3.91.3-1.5-2.60.90.62.7-1.31.5-3.81.0-1.54.0-2.31.4-0.10.40.0-0.1-0.1-0.20.30.20.20.2-0.60.40.2-1.0-0.6-0.1-0.2-0.20.2
Percentage of ForeignCurrencyTransactionGainLossUnrealized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnDerivativeInstrumentsNetPretax us-gaap:LongtermDebtType, us-gaap:SubsidiarySaleOfStock

us-gaap:GainLossOnDerivativeInstrumentsNetPretax

ajg:SeniorUnsecuredNote, us-gaap:PrivatePlacement


Gain
Period End2021-05-20
Value-57800000.0
Percentage of GainLossOnDerivativeInstrumentsNetPretax100.0

us-gaap:GoodwillAcquiredDuringPeriod

us-gaap:GoodwillAcquiredDuringPeriod


Goodwill
Period End2021-03-312020-03-312019-03-312018-03-312017-03-312016-03-312015-03-312014-03-312013-03-312012-03-31
Value28815913141913343205.535
Percentage of GoodwillAcquiredDuringPeriod100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GoodwillAcquiredDuringPeriod us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Goodwill
Period End2021-03-312020-03-312019-03-312018-03-312017-03-312016-03-312015-03-312014-03-312013-03-312012-03-31
Value26915913138913343205.535
Percentage of GoodwillAcquiredDuringPeriod93.4100.0100.093.4100.0100.0100.0100.0100.0100.0

ajg:RiskManagementSegment


Goodwill
Period End2021-03-312018-03-312015-03-31
Value192.70.0
Percentage of GoodwillAcquiredDuringPeriod6.66.60.0

us-gaap:GoodwillPurchaseAccountingAdjustments

us-gaap:GoodwillPurchaseAccountingAdjustments


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value0.4521.01.310.019-18.88.68.4-1.51.20.6-0.40.3-0.3131.61.4-0.21.90.3-9.52.2292.918-2.23.4-28.90.00.0-0.33.6-1.61.6-0.3-0.50.07.2
Percentage of GoodwillPurchaseAccountingAdjustments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.00.0100.0

us-gaap:GoodwillPurchaseAccountingAdjustments us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value0.4520.61.39.8181.5-18.68.98.4-1.51.20.61.90.3-0.3131.61.4-0.21.9-1.3-9.52.2292.918-2.23.4-28.90.00.0-0.33.6-1.21.2-0.1-0.50.05.6
Percentage of GoodwillPurchaseAccountingAdjustments100.0100.060.0100.098.094.30.098.9103.5100.0100.0100.0100.0-475.0100.0100.0100.0100.0100.0100.0100.0-433.3100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.075.075.033.3100.00.077.8

ajg:RiskManagementSegment


Goodwill
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302012-12-312012-09-302011-12-31
Value0.40.00.21.10.3-0.20.00.00.0-2.30.00.00.01.60.00.00.00.00.00.0-0.40.40.0
Percentage of GoodwillPurchaseAccountingAdjustments40.00.02.05.70.01.1-0.00.00.0575.00.0-0.00.0533.3-0.00.00.00.00.0-0.025.025.00.0

us-gaap:GoodwillTranslationAndPurchaseAccountingAdjustments

us-gaap:GoodwillTranslationAndPurchaseAccountingAdjustments


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value204413464159-241.782-60.1-39.842-54.1-14.0-86.530-39.2981635-74.4-10.6-35.6-3.3-16.0-94.422-78.2-90.5-74.1246.18.714-32.6130.19.4-5.45.2-1.9-5.1
Percentage of GoodwillTranslationAndPurchaseAccountingAdjustments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GoodwillTranslationAndPurchaseAccountingAdjustments us-gaap:StatementBusinessSegments

ajg:BrokerageSegment


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value204313263157-237.681-59.5-39.141-54.2-13.3-85.430-38.9971635-74.1-10.5-35.3-3.2-15.9-94.321-78.1-90.2-74.1236.18.614-32.4130.19.3-5.45.2-1.9-5.1
Percentage of GoodwillTranslationAndPurchaseAccountingAdjustments100.099.198.498.398.298.398.499.098.298.8100.295.098.798.499.299.598.299.799.699.199.297.099.499.999.599.999.7100.099.6100.098.999.399.499.3100.098.9100.0100.0100.0100.0

ajg:RiskManagementSegment


Goodwill
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-06-302013-03-312012-12-31
Value0.00.42.9-3.91.4-0.6-0.70.50.0-0.5-1.00.6-0.40.5-0.3-0.1-0.3-0.1-0.1-0.10.1-0.1-0.30.0-0.20.10.0
Percentage of GoodwillTranslationAndPurchaseAccountingAdjustments0.00.91.81.61.71.01.81.2-0.03.61.21.91.00.50.40.90.83.00.60.10.50.10.3-0.00.60.70.0

us-gaap:Corporate


Goodwill
Period End2020-12-312020-09-302020-06-302020-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value0.00.10.0-0.20.1-0.2-0.1-0.10.10.00.00.10.00.00.00.00.00.0
Percentage of GoodwillTranslationAndPurchaseAccountingAdjustments0.00.20.00.1-0.21.40.1-0.3-0.30.00.00.3-0.0-0.00.0-0.0-0.0-0.0

us-gaap:ImpairmentOfIntangibleAssetsFinitelived us-gaap:StatementBusinessSegments

us-gaap:ImpairmentOfIntangibleAssetsFinitelived

ajg:BrokerageSegment


Impairment
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-06-302019-03-31
Value8.05.13.70.2450.00.0
Percentage of ImpairmentOfIntangibleAssetsFinitelived100.0100.0100.0100.0100.00.00.0

us-gaap:IncomeTaxCreditsAndAdjustments

us-gaap:IncomeTaxCreditsAndAdjustments


Income
Period End2021-06-302021-03-312020-12-31
Value0.01080.0
Percentage of IncomeTaxCreditsAndAdjustments0.0100.00.0

us-gaap:IncreaseDecreaseInAccruedIncomeTaxesPayable

us-gaap:IncreaseDecreaseInAccruedIncomeTaxesPayable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-23.5-7.4-10.027312.630-0.4-29.935-51.71.0-11.5162.810-5.7-5.9-16.212-3.7-3.4-6.814-8.3-18.2-1.05.26.3-5.6-5.26.45.1-2.01.1-3.017-1.7-0.4-8.42.6-4.2-42.4105.23.5
Percentage of IncreaseDecreaseInAccruedIncomeTaxesPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInContractWithCustomerLiability

us-gaap:IncreaseDecreaseInContractWithCustomerLiability


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-1.537-6.46.5134.5-4.3-9.98.418-14.60.63.129
Percentage of IncreaseDecreaseInContractWithCustomerLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.12245504137124425674722707550605517346145164957522.1502930161710187.423-2.01.3-2.6-2.3-19.0-7.3-3.1-12.1-5.7-7.8-5.1
Percentage of IncreaseDecreaseInDeferredIncomeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingAssets

us-gaap:IncreaseDecreaseInOtherOperatingAssets


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value166-113.852127103-206.4535783-133.45777118-119.1237.673-56.2262.7111-85.9-9.07.2120-84.427663620-14.147-27.451-40.224-9.1-27.1261612-13.6-5.212-13.710
Percentage of IncreaseDecreaseInOtherOperatingAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInReinsurancePayables

us-gaap:IncreaseDecreaseInReinsurancePayables


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value4091208-441.8-127.6-139.51863-381.7-235.920287690-377.8127979135-246.4475-30.1264-385.3587-114.2187-105.8405-81.421-5.7239-195.1121-178.4206-35.688-405.9339119.6-339.3312-53.4-63.5-165.6247-25.3
Percentage of IncreaseDecreaseInReinsurancePayables100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements


Incremental
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value4500000.04500000.0-100000.04400000.03600000.04500000.004400000.04000000.03900000.0200000.03500000.03100000.03500000.0200000.02000000.01700000.01700000.00900000.0900000.0600000.0-100000.0800000.01100000.01200000.001300000.01400000.01600000.001500000.01600000.01400000.001400000.01500000.01400000.0100000.0500000.0800000.01000000.0100000.0200000.0200000.0
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestPaid

us-gaap:InterestPaid


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value435144534645494445294032372834283130302825292228232822318.3198.8175.7174.2165.0164.6164.2134.5124.512
Percentage of InterestPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LaborAndRelatedExpense

us-gaap:LaborAndRelatedExpense


Labor
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value937975881873815896857838806837760765724775738680675657659626631622633604615575606564530466473412415383411373364344364341324295299280275262
Percentage of LaborAndRelatedExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:NotesIssued1 us-gaap:ExtinguishmentOfDebt, us-gaap:LongtermDebtType, us-gaap:SubsidiarySaleOfStock

us-gaap:NotesIssued1

ajg:FixedRateOfThreePointFiveZeroPercentBalloonDueMayTwentyTwoThousandFiftyOne, ajg:SeniorUnsecuredNote, us-gaap:PrivatePlacement


Notes
Period End2021-05-20
Value850
Percentage of NotesIssued1100.0

ajg:FixedRateOfTwoPointFiveZeroPercentBalloonDueMayTwentyTwoThousandThirtyOne, ajg:SeniorUnsecuredNote, us-gaap:PrivatePlacement


Notes
Period End2021-05-20
Value650
Percentage of NotesIssued176.5

us-gaap:NotesIssued1 us-gaap:LongtermDebtType, us-gaap:SubsidiarySaleOfStock

ajg:SeniorUnsecuredNote, us-gaap:PrivatePlacement


Notes
Period End2021-05-20
Value1500
Percentage of NotesIssued1176.5

us-gaap:OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax

us-gaap:OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value3058212101250-381.3128-98.7-60.774-84.1-25.2-150.762-66.31573358-140.4-19.6-59.1-12.7-23.2-152.749-134.8-156.4-136.5458.81129-15.9-23.1-1.319-12.610-1.1-16.0-3.04.03.410-4.3
Percentage of OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-33.256159.5-1.8-91.435-24.9-21.1-11.8
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value-33.2569.5-1.8-91.4-24.9-21.1-11.8
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-46.17417108.1-121.343-34.0-29.4-17.2
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax us-gaap:DerivativeInstrumentRisk, us-gaap:IncomeStatementLocation

us-gaap:ForeignExchangeContract, ajg:CommissionRevenue


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-4.4-1.75.77.02.0-19.315-6.0-3.63.7
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax9.5-2.331.867.324.715.936.317.612.2-21.5

us-gaap:InterestRateContract, us-gaap:InterestExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-41.775123.46.1-102.027-28.0-25.8-20.9
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax90.5102.368.232.775.384.163.782.487.8121.5

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value-10.9191.60.0-28.9-8.2-7.1-4.4
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationTax100.0100.0100.00.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value-2000000.0-1700000.010200000.0-6400000.03700000.0-1200000.08200000.0-4900000.0
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value-0.1-1.01.2-0.40.0-1.2-1.3-1.0-0.8-1.612-0.75.5-7.0-0.6-1.1-1.4-1.28.8-0.8-2.8-0.80.0-0.60.0-0.720-0.5-0.7-0.2-26.4-0.20.9-1.11.41.02.21.2290.20.2
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-09-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value-0.1-1.0-0.4-1.2-1.0-0.8-1.612-0.7-0.6-7.0-0.6-1.1-1.4-1.28.8-0.8-2.8-0.80.0-0.60.0-0.720-0.5-0.7-0.2-26.4-0.20.9-1.11.41.0
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0-10.9100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax


Other
Period End2021-06-302021-03-312020-09-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value0.10.20.10.30.20.21.00.13.74.6
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value1.51.41.51.51.51.61.61.81.81.81.21.31.21.20.91.41.31.4-9.41.31.31.51.51.51.61.6120.60.60.613-9.81.92.012
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForCapitalImprovements

us-gaap:PaymentsForCapitalImprovements


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value32271920292931323639332831313528362979
Percentage of PaymentsForCapitalImprovements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromInvestments

us-gaap:PaymentsForProceedsFromInvestments


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value0.30.40.40.40.20.4510.30.30.4150.4-1.00.70.32.31.15.29.6105.56.58.9136.01.30.6-0.5163.14.912135.39.22.5
Percentage of PaymentsForProceedsFromInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsOfDebtIssuanceCosts

us-gaap:PaymentsOfDebtIssuanceCosts


Payments
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.00.00.01.30.00.03.70.2
Percentage of PaymentsOfDebtIssuanceCosts0.00.00.0100.00.00.0100.0100.0

us-gaap:PaymentsToAcquireBusinessesGross

us-gaap:PaymentsToAcquireBusinessesGross


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-012016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-30
Value1494422418.45.0143310214572176231136361627285711431074.651474110995202477442138013428201
Percentage of PaymentsToAcquireBusinessesGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToMinorityShareholders

us-gaap:PaymentsToMinorityShareholders


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value11108.0-5.06.674359.51910238.7138.68.9107.97.69.0158.18.99.8109.3109.39.08.08.0
Percentage of PaymentsToMinorityShareholders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromIssuanceOfCommonStock


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value146437282534231818323212221532101514208.815146.84.310170183612929181113242721122126198.12026103.31112
Percentage of ProceedsFromIssuanceOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromLinesOfCredit

us-gaap:ProceedsFromLinesOfCredit


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-312010-09-30
Value4954300.0808201730158073597510257804909908154201113115595511205976903323152712461792147503367445217210181410.05.015749170.00.0
Percentage of ProceedsFromLinesOfCredit100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.00.00.0

us-gaap:RepaymentsOfLinesOfCredit

us-gaap:RepaymentsOfLinesOfCredit


Repayments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-312010-09-30
Value4954300.01801000197014506709101030645495121564530513561232838110057476122127327320642991537175305082260971248497539520.00.0
Percentage of RepaymentsOfLinesOfCredit100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0

us-gaap:RestrictedStockExpense us-gaap:AwardType

us-gaap:RestrictedStockExpense

us-gaap:PerformanceShares


Restricted
Period End2021-06-302021-03-312020-06-302020-03-31
Value3.23.02.46.1
Percentage of RestrictedStockExpense100.0100.0100.0100.0

us-gaap:RestrictedStockUnitsRSU


Restricted
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value7.65.9118.99.5107.37.78.46.46.66.08.26.54.44.76.54.04.04.26.0
Percentage of RestrictedStockExpense237.5196.70.00.0395.8173.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue

ajg:UnvestedRestrictedStock


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1.346-28.60.00.8290.10.02.00.01.20.01.221
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue100.0100.0100.00.0100.0100.0100.00.0100.00.0100.00.0100.0100.0

us-gaap:PerformanceShares


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-0.4190.00.00.0120.00.00.05.70.00.00.03.70.50.00.02.8
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue-30.841.8-0.00.00.041.90.00.00.00.00.00.00.017.50.00.00.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-31
Value022.9017.12700.1730000.1560000.1510000.2720000.2770000.2820000.2890000.29600.00200.2670000.2680
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate0.0100.00.0100.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.0100.00.0100.00.00.00.0100.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-31
Value00.900.69300.0070000.0250000.0270000.0230000.0160000.0180000.0180000.0120000.0120000.0270
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate0.0100.00.0100.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue

ajg:DeferredEquityParticipationPlan


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value54329192448235174.030224210183192-3.0121661532.822
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod


Share
Period End2020-12-31
Value-100000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross


Share
Period End2021-06-302021-03-312020-12-31
Value01600000.00
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross0.0100.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue us-gaap:ValuationTechnique

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue

ajg:BlackScholesOptionPricingModel


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value023.380009.9900010.710009.2700011.420008.450009.250009.660007.510
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue0.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.0

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice


Share
Period End2021-06-302021-03-312020-12-31
Value-0.2149.640.33
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice


Share
Period End2020-12-31
Value0.84
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice100.0

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice


Share
Period End2021-06-302021-03-312020-12-31
Value0127.90
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice0.0100.00.0

us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit

us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit


Share
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value043.710043.7100039.17009.6226.0900023.7600023.7600021.2800
Percentage of ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit0.0100.00.00.0100.00.00.00.0100.00.00.0100.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.0

us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRange

ajg:Range01


Share
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value043.710043.7100039.17009.6226.0900023.7600023.7600021.280010.710.5800010.584.79005.79
Percentage of ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit0.0100.00.00.0100.00.00.00.0100.00.00.0100.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.00.00.00.00.00.00.00.00.00.0

ajg:Range02


Share
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30<