0001267395 2019-01-01 2019-12-31 0001267395 2020-03-06 0001267395 srt:RestatementAdjustmentMember us-gaap:RetainedEarningsMember 2017-01-01 2017-12-31 0001267395 us-gaap:SeriesDPreferredStockMember 2018-12-31 0001267395 2018-12-31 0001267395 2019-12-31 0001267395 us-gaap:SeriesFPreferredStockMember 2018-12-31 0001267395 us-gaap:SeriesDPreferredStockMember 2019-12-31 0001267395 us-gaap:SeriesFPreferredStockMember 2019-12-31 0001267395 us-gaap:SeriesEPreferredStockMember 2019-12-31 0001267395 us-gaap:SeriesEPreferredStockMember 2018-12-31 0001267395 us-gaap:FixedIncomeInvestmentsMember 2018-12-31 0001267395 us-gaap:ShortTermInvestmentsMember 2018-12-31 0001267395 us-gaap:FixedIncomeInvestmentsMember 2019-12-31 0001267395 us-gaap:ShortTermInvestmentsMember 2019-12-31 0001267395 us-gaap:SeriesFPreferredStockMember 2019-01-01 2019-12-31 0001267395 us-gaap:SeriesEPreferredStockMember 2019-01-01 2019-12-31 0001267395 2018-01-01 2018-12-31 0001267395 us-gaap:SeriesEPreferredStockMember 2018-01-01 2018-12-31 0001267395 us-gaap:SeriesDPreferredStockMember 2019-01-01 2019-12-31 0001267395 us-gaap:SeriesFPreferredStockMember 2018-01-01 2018-12-31 0001267395 us-gaap:SeriesDPreferredStockMember 2018-01-01 2018-12-31 0001267395 2017-01-01 2017-12-31 0001267395 us-gaap:CommonStockMember 2019-12-31 0001267395 us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2018-12-31 0001267395 us-gaap:CommonStockMember 2016-12-31 0001267395 us-gaap:AdditionalPaidInCapitalMember 2018-12-31 0001267395 us-gaap:CommonStockMember us-gaap:AdditionalPaidInCapitalMember 2018-01-01 2018-12-31 0001267395 us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2016-12-31 0001267395 us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2019-12-31 0001267395 us-gaap:PreferredStockMember us-gaap:RetainedEarningsMember 2019-01-01 2019-12-31 0001267395 us-gaap:CommonStockMember 2018-12-31 0001267395 ahl:MinorityinterestbuyoutMember 2017-01-01 2017-12-31 0001267395 us-gaap:RetainedEarningsMember 2019-01-01 2019-12-31 0001267395 us-gaap:CommonStockMember 2017-12-31 0001267395 us-gaap:AdditionalPaidInCapitalMember 2018-01-01 2018-12-31 0001267395 us-gaap:CommonStockMember 2017-01-01 2017-12-31 0001267395 us-gaap:CommonStockMember us-gaap:AdditionalPaidInCapitalMember 2019-01-01 2019-12-31 0001267395 us-gaap:NoncontrollingInterestMember 2017-12-31 0001267395 us-gaap:NoncontrollingInterestMember 2017-01-01 2017-12-31 0001267395 us-gaap:AccumulatedTranslationAdjustmentMember 2018-01-01 2018-12-31 0001267395 us-gaap:AccountingStandardsUpdate201609Member us-gaap:RetainedEarningsMember 2017-12-31 0001267395 us-gaap:PreferredStockMember 2018-12-31 0001267395 us-gaap:RetainedEarningsMember 2018-12-31 0001267395 us-gaap:AccumulatedTranslationAdjustmentMember 2016-12-31 0001267395 us-gaap:PreferredStockMember us-gaap:RetainedEarningsMember 2018-01-01 2018-12-31 0001267395 us-gaap:CommonStockMember 2019-01-01 2019-12-31 0001267395 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2016-12-31 0001267395 us-gaap:PreferredStockMember us-gaap:AdditionalPaidInCapitalMember 2018-01-01 2018-12-31 0001267395 us-gaap:AdditionalPaidInCapitalMember 2017-01-01 2017-12-31 0001267395 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2017-12-31 0001267395 us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2017-12-31 0001267395 us-gaap:RetainedEarningsMember 2019-12-31 0001267395 us-gaap:AccumulatedTranslationAdjustmentMember 2019-12-31 0001267395 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2018-12-31 0001267395 2017-12-31 0001267395 us-gaap:PreferredStockMember us-gaap:RetainedEarningsMember 2017-01-01 2017-12-31 0001267395 us-gaap:AdditionalPaidInCapitalMember 2019-12-31 0001267395 us-gaap:PreferredStockMember us-gaap:AdditionalPaidInCapitalMember 2019-01-01 2019-12-31 0001267395 us-gaap:AccumulatedTranslationAdjustmentMember 2019-01-01 2019-12-31 0001267395 us-gaap:AdditionalPaidInCapitalMember 2017-12-31 0001267395 us-gaap:CommonStockMember us-gaap:AdditionalPaidInCapitalMember 2017-01-01 2017-12-31 0001267395 us-gaap:AccountingStandardsUpdate201609Member us-gaap:RetainedEarningsMember 2018-12-31 0001267395 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2018-01-01 2018-12-31 0001267395 us-gaap:AccumulatedTranslationAdjustmentMember 2017-12-31 0001267395 us-gaap:AdditionalPaidInCapitalMember 2019-01-01 2019-12-31 0001267395 us-gaap:RetainedEarningsMember 2018-01-01 2018-12-31 0001267395 us-gaap:RetainedEarningsMember 2017-12-31 0001267395 us-gaap:AdditionalPaidInCapitalMember 2016-12-31 0001267395 us-gaap:CommonStockMember us-gaap:RetainedEarningsMember 2019-01-01 2019-12-31 0001267395 us-gaap:PreferredStockMember us-gaap:AdditionalPaidInCapitalMember 2017-01-01 2017-12-31 0001267395 ahl:MinorityinterestbuyoutMember 2018-01-01 2018-12-31 0001267395 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2019-12-31 0001267395 us-gaap:NoncontrollingInterestMember 2018-12-31 0001267395 us-gaap:AccumulatedTranslationAdjustmentMember 2018-12-31 0001267395 ahl:MinorityinterestbuyoutMember 2019-01-01 2019-12-31 0001267395 us-gaap:AccountingStandardsUpdate201609Member us-gaap:RetainedEarningsMember 2019-12-31 0001267395 us-gaap:PreferredStockMember us-gaap:AdditionalPaidInCapitalMember 2016-01-01 2016-12-31 0001267395 us-gaap:AccumulatedTranslationAdjustmentMember 2017-01-01 2017-12-31 0001267395 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2019-01-01 2019-12-31 0001267395 us-gaap:RetainedEarningsMember 2017-01-01 2017-12-31 0001267395 us-gaap:CommonStockMember 2018-01-01 2018-12-31 0001267395 us-gaap:PreferredStockMember 2016-12-31 0001267395 us-gaap:NoncontrollingInterestMember 2019-01-01 2019-12-31 0001267395 us-gaap:PreferredStockMember 2017-12-31 0001267395 us-gaap:NoncontrollingInterestMember 2019-12-31 0001267395 us-gaap:CommonStockMember us-gaap:RetainedEarningsMember 2018-01-01 2018-12-31 0001267395 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2017-01-01 2017-12-31 0001267395 us-gaap:NoncontrollingInterestMember 2018-01-01 2018-12-31 0001267395 us-gaap:RetainedEarningsMember 2016-12-31 0001267395 us-gaap:CommonStockMember us-gaap:RetainedEarningsMember 2017-01-01 2017-12-31 0001267395 us-gaap:NoncontrollingInterestMember 2016-12-31 0001267395 us-gaap:SeriesBPreferredStockMember 2017-01-01 2017-12-31 0001267395 us-gaap:SeriesCPreferredStockMember 2017-01-01 2017-12-31 0001267395 us-gaap:AccountingStandardsUpdate201609Member us-gaap:AdditionalPaidInCapitalMember 2017-12-31 0001267395 us-gaap:AccountingStandardsUpdate201609Member us-gaap:AdditionalPaidInCapitalMember 2018-12-31 0001267395 us-gaap:PreferredStockMember 2019-12-31 0001267395 2015-12-31 0001267395 2019-03-31 0001267395 us-gaap:AccountingStandardsUpdate201613Member us-gaap:SubsequentEventMember 2020-01-01 2020-01-01 0001267395 us-gaap:FurnitureAndFixturesMember 2019-01-01 2019-12-31 0001267395 srt:MinimumMember us-gaap:ComputerEquipmentMember 2019-01-01 2019-12-31 0001267395 2019-01-01 0001267395 srt:MaximumMember us-gaap:ComputerEquipmentMember 2019-01-01 2019-12-31 0001267395 us-gaap:AccountingStandardsUpdate201613Member us-gaap:RetainedEarningsMember us-gaap:SubsequentEventMember 2020-01-01 0001267395 us-gaap:LeaseholdImprovementsMember 2019-01-01 2019-12-31 0001267395 us-gaap:FixedMaturitiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:OperatingSegmentsMember ahl:ReinsuranceMember 2019-01-01 2019-12-31 0001267395 us-gaap:OperatingSegmentsMember ahl:InsuranceMember 2019-01-01 2019-12-31 0001267395 ahl:InsuranceMember 2019-01-01 2019-12-31 0001267395 ahl:ReinsuranceMember 2019-01-01 2019-12-31 0001267395 ahl:ReinsuranceMember 2019-12-31 0001267395 ahl:InsuranceMember 2019-12-31 0001267395 us-gaap:OperatingSegmentsMember ahl:ReinsuranceMember 2017-01-01 2017-12-31 0001267395 ahl:ReinsuranceMember 2017-01-01 2017-12-31 0001267395 us-gaap:OperatingSegmentsMember ahl:InsuranceMember 2017-01-01 2017-12-31 0001267395 ahl:InsuranceMember 2017-12-31 0001267395 ahl:InsuranceMember 2017-01-01 2017-12-31 0001267395 ahl:ReinsuranceMember 2017-12-31 0001267395 ahl:CaribbeanMember 2019-01-01 2019-12-31 0001267395 ahl:OtherCountriesMember 2017-01-01 2017-12-31 0001267395 us-gaap:NonUsMember 2019-01-01 2019-12-31 0001267395 country:GB 2019-01-01 2019-12-31 0001267395 srt:EuropeMember 2018-01-01 2018-12-31 0001267395 srt:EuropeMember 2017-01-01 2017-12-31 0001267395 srt:AsiaPacificMember 2018-01-01 2018-12-31 0001267395 us-gaap:NonUsMember 2017-01-01 2017-12-31 0001267395 ahl:UnitedStatesAndCanadaMember 2017-01-01 2017-12-31 0001267395 srt:AsiaPacificMember 2019-01-01 2019-12-31 0001267395 ahl:UnitedStatesAndCanadaMember 2018-01-01 2018-12-31 0001267395 country:GB 2017-01-01 2017-12-31 0001267395 us-gaap:NonUsMember 2018-01-01 2018-12-31 0001267395 country:GB 2018-01-01 2018-12-31 0001267395 ahl:OtherCountriesMember 2019-01-01 2019-12-31 0001267395 srt:AsiaPacificMember 2017-01-01 2017-12-31 0001267395 ahl:WorldwideIncludingUnitedStatesMember 2019-01-01 2019-12-31 0001267395 ahl:WorldwideIncludingUnitedStatesMember 2017-01-01 2017-12-31 0001267395 ahl:WorldwideIncludingUnitedStatesMember 2018-01-01 2018-12-31 0001267395 ahl:CaribbeanMember 2018-01-01 2018-12-31 0001267395 srt:EuropeMember 2019-01-01 2019-12-31 0001267395 ahl:OtherCountriesMember 2018-01-01 2018-12-31 0001267395 ahl:CaribbeanMember 2017-01-01 2017-12-31 0001267395 ahl:UnitedStatesAndCanadaMember 2019-01-01 2019-12-31 0001267395 ahl:InsuranceMember 2018-01-01 2018-12-31 0001267395 ahl:ReinsuranceMember 2018-01-01 2018-12-31 0001267395 ahl:ReinsuranceMember 2018-12-31 0001267395 us-gaap:OperatingSegmentsMember ahl:ReinsuranceMember 2018-01-01 2018-12-31 0001267395 us-gaap:OperatingSegmentsMember ahl:InsuranceMember 2018-01-01 2018-12-31 0001267395 ahl:InsuranceMember 2018-12-31 0001267395 srt:IndustrialPropertyMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 srt:OtherPropertyMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 us-gaap:RetailMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 ahl:InvestmentNetCarryingValueMember us-gaap:GeographicConcentrationRiskMember us-gaap:GeographicDistributionForeignMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 srt:HotelMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 srt:OfficeBuildingMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 us-gaap:RetailMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 ahl:InvestmentNetCarryingValueMember us-gaap:GeographicConcentrationRiskMember us-gaap:GeographicDistributionDomesticMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 srt:OtherPropertyMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 ahl:InvestmentNetCarryingValueMember us-gaap:GeographicConcentrationRiskMember us-gaap:GeographicDistributionForeignMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 ahl:InvestmentNetCarryingValueMember us-gaap:GeographicConcentrationRiskMember us-gaap:GeographicDistributionDomesticMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 srt:IndustrialPropertyMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 srt:ApartmentBuildingMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 srt:ApartmentBuildingMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 srt:OfficeBuildingMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 srt:HotelMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 ahl:BeneAssicurazioniMember 2018-01-01 2018-12-31 0001267395 us-gaap:ShortTermInvestmentsMember 2018-01-01 2018-12-31 0001267395 ahl:PrivatelyheldinvestmentsMember 2019-01-01 2019-12-31 0001267395 us-gaap:CashAndCashEquivalentsMember 2018-01-01 2018-12-31 0001267395 ahl:PrivatelyheldinvestmentsMember 2018-01-01 2018-12-31 0001267395 ahl:MVIMember 2017-01-01 2017-12-31 0001267395 us-gaap:CashAndCashEquivalentsMember 2017-01-01 2017-12-31 0001267395 us-gaap:ShortTermInvestmentsMember 2017-01-01 2017-12-31 0001267395 us-gaap:ShortTermInvestmentsMember 2019-01-01 2019-12-31 0001267395 ahl:ChasparkMaritimeHoldingsLtdMember 2017-01-01 2017-12-31 0001267395 us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember ahl:AgriLogicMember 2019-01-01 2019-12-31 0001267395 ahl:BeneAssicurazioniMember 2019-01-01 2019-12-31 0001267395 ahl:ChasparkMaritimeHoldingsLtdMember 2019-01-01 2019-12-31 0001267395 us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember ahl:AgriLogicMember 2018-01-01 2018-12-31 0001267395 ahl:MVIMember 2018-01-01 2018-12-31 0001267395 ahl:BeneAssicurazioniMember 2017-01-01 2017-12-31 0001267395 ahl:PrivatelyheldinvestmentsMember 2017-01-01 2017-12-31 0001267395 ahl:MVIMember 2019-01-01 2019-12-31 0001267395 us-gaap:CashAndCashEquivalentsMember 2019-01-01 2019-12-31 0001267395 us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember ahl:AgriLogicMember 2017-01-01 2017-12-31 0001267395 ahl:DigitalRiskMember 2019-01-01 2019-12-31 0001267395 ahl:DigitalRiskMember 2017-01-01 2017-12-31 0001267395 ahl:DigitalRiskMember 2018-01-01 2018-12-31 0001267395 ahl:ChasparkMaritimeHoldingsLtdMember 2018-01-01 2018-12-31 0001267395 us-gaap:ProductMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 ahl:MiddlemarketloansMember 2019-12-31 0001267395 ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 us-gaap:EnergyCommoditiesAndServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 us-gaap:EnergyCommoditiesAndServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 ahl:IndustrialServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 ahl:ConsumerDiscretionaryServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 us-gaap:TechnologyServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 us-gaap:ProductMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 ahl:ConsumerDiscretionaryServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 us-gaap:HealthCareMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 us-gaap:FinancialServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 ahl:ConsumerStaplesServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 ahl:IndustrialServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 us-gaap:FinancialServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 us-gaap:HealthCareMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 ahl:ConsumerStaplesServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 us-gaap:TechnologyServiceMember ahl:InvestmentNetCarryingValueMember us-gaap:ProductConcentrationRiskMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 ahl:InvestmentNetCarryingValueMember us-gaap:GeographicConcentrationRiskMember us-gaap:GeographicDistributionDomesticMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 ahl:InvestmentNetCarryingValueMember us-gaap:GeographicConcentrationRiskMember us-gaap:GeographicDistributionForeignMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 ahl:InvestmentNetCarryingValueMember us-gaap:GeographicConcentrationRiskMember us-gaap:GeographicDistributionForeignMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 ahl:InvestmentNetCarryingValueMember us-gaap:GeographicConcentrationRiskMember us-gaap:GeographicDistributionDomesticMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 ahl:DebtServiceCoverageRatioLessThan1.00xMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 ahl:DebtServiceCoverageRatioGreaterThan1.2xMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 ahl:DebtServiceCoverageRatio1.00to1.20xMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 us-gaap:AssetBackedSecuritiesMember 2018-12-31 0001267395 us-gaap:USTreasurySecuritiesMember 2018-12-31 0001267395 us-gaap:MunicipalBondsMember 2018-12-31 0001267395 us-gaap:AvailableforsaleSecuritiesMember 2018-12-31 0001267395 us-gaap:CorporateDebtSecuritiesMember 2018-12-31 0001267395 us-gaap:MortgageBackedSecuritiesMember 2018-12-31 0001267395 us-gaap:ForeignGovernmentDebtSecuritiesMember 2018-12-31 0001267395 us-gaap:ForeignCorporateDebtSecuritiesMember 2018-12-31 0001267395 us-gaap:USGovernmentAgenciesDebtSecuritiesMember 2018-12-31 0001267395 ahl:DebtServiceCoverageRatio1.00to1.20xMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 ahl:DebtServiceCoverageRatioLessThan1.00xMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 ahl:DebtServiceCoverageRatioGreaterThan1.2xMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FixedMaturitiesMember 2019-12-31 0001267395 us-gaap:MortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 ahl:NonagencycommercialmortgagebackedsecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:AssetBackedSecuritiesMember 2019-12-31 0001267395 us-gaap:AssetBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:FixedIncomeSecuritiesMember 2019-01-01 2019-12-31 0001267395 ahl:NonagencycommercialmortgagebackedsecuritiesMember 2019-12-31 0001267395 us-gaap:MortgageBackedSecuritiesMember 2019-12-31 0001267395 ahl:MVIMember 2018-12-31 0001267395 ahl:BeneAssicurazioniMember 2018-12-31 0001267395 ahl:DigitalRiskMember 2017-12-31 0001267395 ahl:CropReMember 2019-01-01 2019-12-31 0001267395 ahl:BeneAssicurazioniMember 2017-12-31 0001267395 ahl:MVIMember 2019-12-31 0001267395 ahl:CropReMember 2018-01-01 2018-12-31 0001267395 ahl:CropReMember 2019-12-31 0001267395 ahl:BeneAssicurazioniMember 2019-12-31 0001267395 ahl:DigitalRiskMember 2018-12-31 0001267395 ahl:CropReMember 2018-12-31 0001267395 ahl:DigitalRiskMember 2019-12-31 0001267395 ahl:CropReMember 2017-12-31 0001267395 ahl:MVIMember 2017-12-31 0001267395 ahl:TotalTradingMember 2018-12-31 0001267395 ahl:CatastropheBondsMember 2018-12-31 0001267395 ahl:TradingFixedMaturityInvestmentsMember 2018-12-31 0001267395 ahl:TotalTradingMember 2019-12-31 0001267395 ahl:PrivatelyheldinvestmentsMember 2019-12-31 0001267395 ahl:TradingFixedMaturityInvestmentsMember 2019-12-31 0001267395 us-gaap:MunicipalBondsMember 2019-12-31 0001267395 ahl:CatastropheBondsMember 2019-12-31 0001267395 us-gaap:USTreasurySecuritiesMember 2019-12-31 0001267395 us-gaap:CorporateDebtSecuritiesMember 2019-12-31 0001267395 us-gaap:EquitySecuritiesMember 2019-12-31 0001267395 ahl:SecuritiesassetbackedMember 2019-12-31 0001267395 us-gaap:ForeignGovernmentDebtSecuritiesMember 2019-12-31 0001267395 us-gaap:FixedMaturitiesMember 2018-12-31 0001267395 us-gaap:DebtSecuritiesMember 2018-12-31 0001267395 ahl:MVIMember 2015-01-01 2015-01-31 0001267395 ahl:PrivatelyheldinvestmentsMember 2018-12-31 0001267395 ahl:CropReMember 2017-12-18 2017-12-18 0001267395 ahl:ChasparkMaritimeHoldingsLtdMember 2012-10-02 0001267395 ahl:ManagedPortfolioMember 2019-01-01 2019-12-31 0001267395 ahl:CropReMember 2017-12-18 0001267395 ahl:AgriLogicConsultingLLCMember 2018-09-18 0001267395 us-gaap:RealEstateFundsMember 2019-01-01 2019-12-31 0001267395 us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember us-gaap:CustomerRelatedIntangibleAssetsMember ahl:AgriLogicConsultingLLCMember 2018-09-18 0001267395 ahl:BBBEmergingMarketDebtMember 2019-01-01 2019-12-31 0001267395 us-gaap:RealEstateFundsMember us-gaap:LimitedPartnerMember 2018-09-19 0001267395 ahl:ManagedPortfolioMember 2018-01-01 2018-12-31 0001267395 ahl:MMLandCMLMember 2019-01-01 2019-12-31 0001267395 ahl:CGBInsuranceDiversifiedServicesInc.Member ahl:CropReMember 2017-12-18 0001267395 us-gaap:RealEstateFundsMember us-gaap:LimitedPartnerMember 2017-12-31 0001267395 us-gaap:RealEstateFundsMember us-gaap:LimitedPartnerMember 2018-05-01 0001267395 ahl:DigitalRiskMember 2017-01-01 0001267395 us-gaap:EquityFundsMember 2019-12-27 0001267395 ahl:BeneAssicurazioniMember 2016-07-26 2016-07-26 0001267395 us-gaap:EquityFundsMember 2019-12-23 0001267395 ahl:BeneAssicurazioniMember 2016-07-26 0001267395 ahl:ShorttermInvestmentTradingMember 2018-01-01 2018-12-31 0001267395 ahl:CatastropheBondsMember 2018-01-01 2018-12-31 0001267395 us-gaap:OtherAggregatedInvestmentsMember 2017-01-01 2017-12-31 0001267395 ahl:CatastropheBondsMember 2019-01-01 2019-12-31 0001267395 us-gaap:FixedIncomeSecuritiesMember 2018-01-01 2018-12-31 0001267395 ahl:ShorttermInvestmentTradingMember 2017-01-01 2017-12-31 0001267395 us-gaap:DebtSecuritiesMember 2018-01-01 2018-12-31 0001267395 us-gaap:OtherAggregatedInvestmentsMember 2018-01-01 2018-12-31 0001267395 us-gaap:EquitySecuritiesMember 2018-01-01 2018-12-31 0001267395 us-gaap:DebtSecuritiesMember 2017-01-01 2017-12-31 0001267395 ahl:ShorttermInvestmentTradingMember 2019-01-01 2019-12-31 0001267395 us-gaap:DebtSecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:FixedIncomeSecuritiesMember 2017-01-01 2017-12-31 0001267395 us-gaap:EquitySecuritiesMember 2019-01-01 2019-12-31 0001267395 ahl:CatastropheBondsMember 2017-01-01 2017-12-31 0001267395 us-gaap:OtherAggregatedInvestmentsMember 2019-01-01 2019-12-31 0001267395 us-gaap:EquitySecuritiesMember 2017-01-01 2017-12-31 0001267395 us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FixedMaturitiesMember 2018-12-31 0001267395 us-gaap:AssetBackedSecuritiesMember 2018-01-01 2018-12-31 0001267395 us-gaap:MortgageBackedSecuritiesMember 2018-01-01 2018-12-31 0001267395 us-gaap:CommercialMortgageBackedSecuritiesMember ahl:DebttoValueRatio61to70PercentMember 2019-12-31 0001267395 us-gaap:CommercialMortgageBackedSecuritiesMember ahl:DebttoValueRatio50to60PercentMember 2019-12-31 0001267395 us-gaap:CommercialMortgageBackedSecuritiesMember ahl:DebttoValueRatio71to80PercentMember 2019-12-31 0001267395 us-gaap:ForeignCorporateDebtSecuritiesMember 2019-12-31 0001267395 us-gaap:USGovernmentAgenciesDebtSecuritiesMember 2019-12-31 0001267395 us-gaap:DebtSecuritiesMember 2019-12-31 0001267395 us-gaap:FixedMaturitiesMember 2019-12-31 0001267395 us-gaap:AvailableforsaleSecuritiesMember 2019-12-31 0001267395 ahl:MiddlemarketloansMember ahl:DebttoValueRatioLessthan50PercentMember 2019-12-31 0001267395 ahl:MiddlemarketloansMember ahl:DebttoValueRatio50to60PercentMember 2019-12-31 0001267395 ahl:ThirdPartyMember 2018-12-31 0001267395 srt:ParentCompanyMember 2018-01-01 2018-12-31 0001267395 ahl:ThirdPartyMember 2017-12-31 0001267395 srt:ParentCompanyMember 2018-12-31 0001267395 ahl:ThirdPartyMember 2018-01-01 2018-12-31 0001267395 ahl:ThirdPartyMember srt:ParentCompanyMember 2018-01-01 2018-12-31 0001267395 srt:ParentCompanyMember 2017-12-31 0001267395 ahl:ThirdPartyMember 2019-12-31 0001267395 srt:ParentCompanyMember 2019-12-31 0001267395 ahl:ThirdPartyMember srt:ParentCompanyMember 2019-01-01 2019-12-31 0001267395 srt:ParentCompanyMember 2019-01-01 2019-12-31 0001267395 ahl:ThirdPartyMember 2019-01-01 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:MiddlemarketloansMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 srt:MinimumMember us-gaap:FairValueInputsLevel3Member ahl:MiddlemarketloansMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 srt:MinimumMember us-gaap:FairValueInputsLevel3Member us-gaap:CommercialMortgageBackedSecuritiesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 srt:WeightedAverageMember us-gaap:FairValueInputsLevel3Member us-gaap:AssetBackedSecuritiesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:EquitySecuritiesMember us-gaap:ValuationTechniqueOptionPricingModelMember 2019-12-31 0001267395 srt:MaximumMember us-gaap:FairValueInputsLevel3Member us-gaap:CommercialMortgageBackedSecuritiesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 srt:MaximumMember us-gaap:FairValueInputsLevel3Member us-gaap:AssetBackedSecuritiesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 srt:WeightedAverageMember us-gaap:FairValueInputsLevel3Member us-gaap:CommercialMortgageBackedSecuritiesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CommercialMortgageBackedSecuritiesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 srt:MinimumMember us-gaap:FairValueInputsLevel3Member us-gaap:AssetBackedSecuritiesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 srt:WeightedAverageMember us-gaap:FairValueInputsLevel3Member ahl:MiddlemarketloansMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 srt:MaximumMember us-gaap:FairValueInputsLevel3Member ahl:MiddlemarketloansMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CommercialMortgageBackedSecuritiesMember us-gaap:ValuationTechniqueOptionPricingModelMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:RealEstateFundsMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USGovernmentAgenciesDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:USGovernmentAgenciesDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 ahl:NonagencycommercialmortgagebackedsecuritiesMember us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USGovernmentAgenciesDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:RealEstateFundsMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 ahl:NonagencycommercialmortgagebackedsecuritiesMember us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:RealEstateFundsMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AvailableforsaleSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ShortTermInvestmentsMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember ahl:ShortTermInvestmentsTradingAtFairValueMember 2019-12-31 0001267395 us-gaap:InterestRateContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:RealEstateFundsMember 2019-12-31 0001267395 us-gaap:InterestRateContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:AvailableforsaleSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 ahl:NonagencycommercialmortgagebackedsecuritiesMember us-gaap:FairValueMeasurementsRecurringMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember ahl:ShortTermInvestmentsTradingAtFairValueMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AvailableforsaleSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember ahl:ShortTermInvestmentsTradingAtFairValueMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ShortTermInvestmentsMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:InterestRateContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 ahl:NonagencycommercialmortgagebackedsecuritiesMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ShortTermInvestmentsMember 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ShortTermInvestmentsMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USGovernmentAgenciesDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:ShortTermInvestmentsTradingAtFairValueMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AvailableforsaleSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2019-12-31 0001267395 us-gaap:InterestRateContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2019-12-31 0001267395 ahl:Silverton2016ThirdpartyFundedMember 2016-10-01 2016-12-31 0001267395 ahl:Silverton2015ThirdpartyFundedMember 2014-10-01 2014-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 ahl:Silverton2017ThirdpartyFundedMember 2018-01-01 2018-12-31 0001267395 ahl:Silverton2016Member 2016-10-01 2016-12-31 0001267395 ahl:Silverton2017Member 2017-10-01 2017-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:Silverton2016Member 2018-01-01 2018-12-31 0001267395 ahl:Silverton2015Member 2014-10-01 2014-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:SilvertonMember 2019-01-01 2019-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:EquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:LiabilityMember us-gaap:FairValueMeasurementsRecurringMember 2018-01-01 2018-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:MiddlemarketloansMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2019-01-01 2019-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:EquitySecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2019-01-01 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:EquitySecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:LiabilityMember us-gaap:FairValueMeasurementsRecurringMember ahl:SilvertonMember 2019-01-01 2019-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CommercialMortgageBackedSecuritiesMember 2018-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:MiddlemarketloansMember 2019-01-01 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:LiabilityMember us-gaap:FairValueMeasurementsRecurringMember 2019-01-01 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:LiabilityMember us-gaap:FairValueMeasurementsRecurringMember ahl:SilvertonMember 2018-01-01 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:LiabilityMember us-gaap:FairValueMeasurementsRecurringMember ahl:SilvertonMember 2018-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:LiabilityMember us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:EquitySecuritiesMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:LiabilityMember us-gaap:FairValueMeasurementsRecurringMember ahl:SilvertonMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2017-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:AssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:LiabilityMember us-gaap:FairValueMeasurementsRecurringMember ahl:SilvertonMember 2017-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:MiddlemarketloansMember 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CommercialMortgageBackedSecuritiesMember 2019-01-01 2019-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:LiabilityMember us-gaap:FairValueMeasurementsRecurringMember 2019-12-31 0001267395 srt:MinimumMember us-gaap:FairValueInputsLevel3Member 2018-01-01 2018-12-31 0001267395 srt:MaximumMember us-gaap:FairValueInputsLevel3Member 2018-01-01 2018-12-31 0001267395 srt:MinimumMember us-gaap:FairValueInputsLevel3Member 2018-12-31 0001267395 srt:MaximumMember us-gaap:FairValueInputsLevel3Member 2018-12-31 0001267395 srt:MaximumMember us-gaap:FairValueInputsLevel3Member us-gaap:MeasurementInputExpectedTermMember 2018-01-01 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:Silverton2016Member 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USGovernmentAgenciesDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember ahl:ShortTermInvestmentsTradingAtFairValueMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:RealEstateFundsMember 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AvailableforsaleSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:RealEstateFundsMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USGovernmentAgenciesDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember ahl:ShortTermInvestmentsTradingAtFairValueMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AvailableforsaleSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:RealEstateFundsMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsAssetsMember us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ShortTermInvestmentsMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AvailableforsaleSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ShortTermInvestmentsMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ShortTermInvestmentsMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:AvailableforsaleSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember ahl:ShortTermInvestmentsTradingAtFairValueMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:USGovernmentAgenciesDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:RealEstateFundsMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ShortTermInvestmentsMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MortgageBackedSecuritiesMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignCorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MunicipalBondsMember us-gaap:TradingAssetsExcludingDebtAndEquitySecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USGovernmentAgenciesDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember ahl:ShortTermInvestmentsTradingAtFairValueMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:AssetBackedSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasurySecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:ForeignGovernmentDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FixedIncomeSecuritiesMember 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember 2018-12-31 0001267395 us-gaap:InterestRateSwapMember us-gaap:NondesignatedMember us-gaap:GainLossOnDerivativeInstrumentsMember 2018-01-01 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:NondesignatedMember 2019-12-31 0001267395 us-gaap:InterestRateSwapMember us-gaap:NondesignatedMember us-gaap:GainLossOnDerivativeInstrumentsMember 2019-01-01 2019-12-31 0001267395 ahl:LiabilitiesUnderDerivativeContractsMember us-gaap:InterestRateSwapMember us-gaap:NondesignatedMember 2019-03-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:NondesignatedMember us-gaap:GainLossOnDerivativeInstrumentsMember 2019-01-01 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DesignatedAsHedgingInstrumentMember us-gaap:GeneralAndAdministrativeExpenseMember 2019-01-01 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DesignatedAsHedgingInstrumentMember ahl:NetchangefromcurrentperiodhedgedtransactionsMember 2019-01-01 2019-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DesignatedAsHedgingInstrumentMember us-gaap:GeneralAndAdministrativeExpenseMember 2018-01-01 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:DesignatedAsHedgingInstrumentMember ahl:NetchangefromcurrentperiodhedgedtransactionsMember 2018-01-01 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:NondesignatedMember us-gaap:GainLossOnDerivativeInstrumentsMember 2018-01-01 2018-12-31 0001267395 us-gaap:InterestRateSwapMember us-gaap:NondesignatedMember 2018-12-31 0001267395 us-gaap:InterestRateSwapMember us-gaap:NondesignatedMember 2019-12-31 0001267395 ahl:LiabilitiesUnderDerivativeContractsMember us-gaap:ForeignExchangeContractMember us-gaap:DesignatedAsHedgingInstrumentMember 2018-12-31 0001267395 us-gaap:ForeignExchangeContractMember us-gaap:NondesignatedMember 2018-12-31 0001267395 ahl:LiabilitiesUnderDerivativeContractsMember us-gaap:InterestRateSwapMember us-gaap:NondesignatedMember 2019-12-31 0001267395 ahl:LiabilitiesUnderDerivativeContractsMember us-gaap:ForeignExchangeContractMember us-gaap:NondesignatedMember 2018-12-31 0001267395 ahl:DerivativeAtFairValueMember us-gaap:ForeignExchangeContractMember us-gaap:NondesignatedMember 2018-12-31 0001267395 ahl:DerivativeAtFairValueMember us-gaap:ForeignExchangeContractMember us-gaap:NondesignatedMember 2019-12-31 0001267395 ahl:LiabilitiesUnderDerivativeContractsMember us-gaap:ForeignExchangeContractMember us-gaap:NondesignatedMember 2019-12-31 0001267395 ahl:LiabilitiesUnderDerivativeContractsMember us-gaap:InterestRateSwapMember us-gaap:NondesignatedMember 2018-12-31 0001267395 ahl:LiabilitiesUnderDerivativeContractsMember us-gaap:ForeignExchangeContractMember us-gaap:DesignatedAsHedgingInstrumentMember 2019-12-31 0001267395 ahl:DerivativeAtFairValueMember us-gaap:ForeignExchangeContractMember us-gaap:DesignatedAsHedgingInstrumentMember 2019-12-31 0001267395 ahl:DerivativeAtFairValueMember us-gaap:ForeignExchangeContractMember us-gaap:DesignatedAsHedgingInstrumentMember 2018-12-31 0001267395 2016-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2019-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2016-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2017-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2015-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2013-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractAccidentYear2019Member 2019-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2019-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2019-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2018-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2019-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember 2019-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2018-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2019-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2018-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2017-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2016-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2017-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2016-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2019-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2015-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2017-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2017-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2019-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2014-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2012-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2015-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2018-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2013-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2018-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2014-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2017-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2016-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2016-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2014-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2018-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2018-12-31 0001267395 us-gaap:PropertyInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2015-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2014-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2013-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2017-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2017-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2019-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2018-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2017-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2014-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember 2019-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2019-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2016-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2019-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2013-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2017-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2019-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember 2018-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2016-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2018-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2019-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2018-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2019-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2016-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2019-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractAccidentYear2019Member 2019-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2015-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2018-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2018-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2012-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2015-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2015-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2018-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2017-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2014-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2015-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2017-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2016-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2018-12-31 0001267395 ahl:CasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2016-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractAccidentYear2019Member 2019-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2019-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2014-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2019-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2018-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2017-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2019-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2017-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2015-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2019-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2017-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2018-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2014-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2019-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2016-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2013-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2018-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2015-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2015-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2018-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2016-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2016-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2017-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2019-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2018-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2019-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2013-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2018-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2015-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2016-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2014-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember 2019-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2016-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2017-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2018-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2017-12-31 0001267395 ahl:MarineAviationandEnergyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2012-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2019-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2016-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember 2019-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2016-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2013-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2019-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2018-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2018-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2019-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2015-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2019-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2017-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2015-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2017-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2016-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2015-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2014-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2017-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2015-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2019-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2014-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2019-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2014-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2017-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2013-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2016-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2017-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2018-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2018-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractAccidentYear2019Member 2019-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2018-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2018-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2017-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2016-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2019-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2018-12-31 0001267395 ahl:FinancialandProfessionalCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2012-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2013-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2018-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2019-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2019-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2014-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2016-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2015-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember 2019-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2016-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2013-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2018-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2015-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2014-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2019-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2014-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2018-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractAccidentYear2019Member 2019-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2017-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2019-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2017-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2015-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2016-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2018-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2017-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2017-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2019-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2016-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2016-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2015-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2017-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2018-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2018-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2018-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2019-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2019-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2017-12-31 0001267395 ahl:AssumedSpecialtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2012-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2015-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2019-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2019-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2016-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2019-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2018-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember 2019-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2016-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2013-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2018-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2018-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2019-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2019-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2014-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2017-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2012-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2015-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2013-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2017-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2014-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2017-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2017-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2014-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2016-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2018-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2018-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2018-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2017-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2019-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractAccidentYear2019Member 2019-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2016-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2016-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2018-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2019-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2015-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2015-12-31 0001267395 ahl:AssumedPropertyCatastropheandOtherPropertyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2017-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2019-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2019-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2018-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2019-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2017-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2019-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2017-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2019-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractAccidentYear2019Member 2019-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2017-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2019-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2018Member 2018-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember 2019-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2017-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2014-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2015-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2019-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2018-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2016-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2013-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2015-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2018-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2015-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2017-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2018-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2016-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2018-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2015-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2016Member 2016-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2015Member 2016-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2016-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2014-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortDurationInsuranceContractsAccidentYear2017Member 2017-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2014Member 2014-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2018-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2013Member 2013-12-31 0001267395 ahl:AssumedCasualtyCommercialInsuranceProductLineMember us-gaap:ShortdurationInsuranceContractsAccidentYear2012Member 2012-12-31 0001267395 us-gaap:OtherShortdurationInsuranceProductLineMember 2019-12-31 0001267395 us-gaap:PropertyAndCasualtyCommercialInsuranceProductLineMember 2019-12-31 0001267395 us-gaap:OtherLongdurationInsuranceProductLineMember 2019-12-31 0001267395 ahl:AssumedPropertyandCasualtyCommercialInsuranceProductLineMember 2019-12-31 0001267395 us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2018-01-01 2018-12-31 0001267395 us-gaap:OfficeOfTheTaxCommissionerBermudaMember 2017-01-01 2017-12-31 0001267395 us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2017-01-01 2017-12-31 0001267395 us-gaap:OfficeOfTheTaxCommissionerBermudaMember 2019-01-01 2019-12-31 0001267395 us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2019-01-01 2019-12-31 0001267395 us-gaap:OfficeOfTheTaxCommissionerBermudaMember 2018-01-01 2018-12-31 0001267395 srt:ScenarioForecastMember us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2020-08-01 2021-03-31 0001267395 us-gaap:ValuationAllowanceOperatingLossCarryforwardsMember 2018-01-01 2018-12-31 0001267395 us-gaap:InternalRevenueServiceIRSMember 2019-12-31 0001267395 us-gaap:InternalRevenueServiceIRSMember 2018-12-31 0001267395 us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2018-12-31 0001267395 us-gaap:OtherComprehensiveIncomeMember 2019-12-31 0001267395 us-gaap:OtherComprehensiveIncomeMember 2018-12-31 0001267395 us-gaap:ValuationAllowanceOperatingLossCarryforwardsMember 2019-01-01 2019-12-31 0001267395 us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2019-12-31 0001267395 us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2017-04-01 2018-03-31 0001267395 us-gaap:HerMajestysRevenueAndCustomsHMRCMember us-gaap:OtherComprehensiveIncomeMember 2019-12-31 0001267395 srt:MinimumMember us-gaap:InternalRevenueServiceIRSMember 2019-01-01 2019-12-31 0001267395 us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2018-01-01 2018-03-31 0001267395 us-gaap:ValuationAllowanceOperatingLossCarryforwardsMember us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2019-12-31 0001267395 2018-01-01 2018-03-31 0001267395 us-gaap:ValuationAllowanceOperatingLossCarryforwardsMember us-gaap:HerMajestysRevenueAndCustomsHMRCMember 2018-12-31 0001267395 ahl:LloydsMember 2019-01-01 2019-12-31 0001267395 ahl:U.SbranchofAspenU.K.Member 2019-01-01 2019-12-31 0001267395 srt:MaximumMember us-gaap:InternalRevenueServiceIRSMember 2019-01-01 2019-12-31 0001267395 us-gaap:HerMajestysRevenueAndCustomsHMRCMember us-gaap:OtherComprehensiveIncomeMember 2018-12-31 0001267395 2013-05-02 0001267395 us-gaap:SeriesFPreferredStockMember 2019-08-13 2019-08-13 0001267395 2019-08-13 0001267395 us-gaap:SeriesEPreferredStockMember 2016-09-20 2016-09-20 0001267395 us-gaap:SeriesDPreferredStockMember 2013-05-02 0001267395 us-gaap:SeriesEPreferredStockMember 2016-01-01 2016-12-31 0001267395 us-gaap:SeriesEPreferredStockMember 2016-12-31 0001267395 us-gaap:SeriesFPreferredStockMember 2019-08-13 0001267395 us-gaap:SeriesBPreferredStockMember 2017-01-03 2017-01-03 0001267395 us-gaap:SeriesCPreferredStockMember 2017-07-01 2017-07-31 0001267395 2017-07-03 0001267395 2017-01-03 0001267395 us-gaap:SeriesBPreferredStockMember 2017-07-03 0001267395 us-gaap:SeriesFPreferredStockMember us-gaap:SubsequentEventMember 2020-02-28 2020-02-28 0001267395 country:BM 2019-12-31 0001267395 country:GB 2019-12-31 0001267395 country:US 2019-12-31 0001267395 country:BM 2019-01-01 2019-12-31 0001267395 ahl:SubsidiariesOneMember 2019-12-31 0001267395 ahl:SubsidiariesOneMember country:BM 2019-12-31 0001267395 country:US 2018-12-31 0001267395 country:BM 2018-12-31 0001267395 country:GB 2018-12-31 0001267395 us-gaap:SeriesEPreferredStockMember us-gaap:SubsequentEventMember 2020-02-28 0001267395 us-gaap:SeriesEPreferredStockMember us-gaap:SubsequentEventMember 2020-02-28 2020-02-28 0001267395 us-gaap:SeriesDPreferredStockMember us-gaap:SubsequentEventMember 2020-02-28 2020-02-28 0001267395 us-gaap:SeriesDPreferredStockMember us-gaap:SubsequentEventMember 2020-02-28 0001267395 us-gaap:SeriesFPreferredStockMember us-gaap:SubsequentEventMember 2020-02-28 0001267395 us-gaap:SeriesFPreferredStockMember 2020-02-28 2020-02-28 0001267395 us-gaap:SeriesEPreferredStockMember 2020-02-28 2020-02-28 0001267395 ahl:DeferredcashawardsMember 2019-01-01 2019-12-31 0001267395 us-gaap:PerformanceSharesMember 2019-01-01 2019-12-31 0001267395 ahl:BlueWatersMember 2016-10-31 2016-10-31 0001267395 ahl:BlueWatersMember 2019-01-01 2019-12-31 0001267395 ahl:BlueWatersMember us-gaap:TrademarksMember 2019-12-31 0001267395 ahl:AspenTrademarkMember 2019-12-31 0001267395 ahl:DigitalRiskMember 2017-01-01 2017-01-01 0001267395 us-gaap:CustomerListsMember 2018-01-01 2018-12-31 0001267395 us-gaap:ContractualRightsMember 2017-12-31 0001267395 us-gaap:NoncompeteAgreementsMember 2017-12-31 0001267395 us-gaap:LicensingAgreementsMember 2018-01-01 2018-12-31 0001267395 us-gaap:NoncompeteAgreementsMember 2018-01-01 2018-12-31 0001267395 us-gaap:CustomerListsMember 2017-12-31 0001267395 us-gaap:ContractualRightsMember 2018-01-01 2018-12-31 0001267395 us-gaap:TrademarksMember 2017-12-31 0001267395 us-gaap:NoncompeteAgreementsMember 2018-12-31 0001267395 us-gaap:TrademarksMember 2018-01-01 2018-12-31 0001267395 us-gaap:TrademarksMember 2018-12-31 0001267395 us-gaap:LicensingAgreementsMember 2017-12-31 0001267395 us-gaap:CustomerListsMember 2018-12-31 0001267395 us-gaap:ContractualRightsMember 2018-12-31 0001267395 us-gaap:LicensingAgreementsMember 2018-12-31 0001267395 us-gaap:CustomerListsMember 2019-01-01 2019-12-31 0001267395 us-gaap:ContractualRightsMember 2019-01-01 2019-12-31 0001267395 us-gaap:LicensingAgreementsMember 2019-01-01 2019-12-31 0001267395 us-gaap:TrademarksMember 2019-12-31 0001267395 us-gaap:TrademarksMember 2019-01-01 2019-12-31 0001267395 us-gaap:NoncompeteAgreementsMember 2019-01-01 2019-12-31 0001267395 us-gaap:LicensingAgreementsMember 2019-12-31 0001267395 us-gaap:NoncompeteAgreementsMember 2019-12-31 0001267395 us-gaap:TrademarksMember 2017-12-18 2017-12-18 0001267395 us-gaap:NoncompeteAgreementsMember 2017-12-18 2017-12-18 0001267395 us-gaap:ContractualRightsMember 2019-12-31 0001267395 us-gaap:CustomerListsMember 2017-12-18 2017-12-18 0001267395 us-gaap:CustomerListsMember 2019-12-31 0001267395 srt:AffiliatedEntityMember 2019-01-01 2019-12-31 0001267395 us-gaap:BeneficialOwnerMember 2019-12-31 0001267395 ahl:ManagementConsultingAgreementMember 2019-12-31 0001267395 us-gaap:AssetManagementArrangementMember 2019-12-31 0001267395 srt:MaximumMember us-gaap:BeneficialOwnerMember 2019-12-31 0001267395 srt:MaximumMember 2019-01-01 2019-12-31 0001267395 srt:MaximumMember 2019-12-31 0001267395 us-gaap:AssetManagementArrangementMember 2019-01-01 2019-12-31 0001267395 srt:AffiliatedEntityMember 2018-12-31 0001267395 us-gaap:LetterOfCreditMember 2018-12-31 0001267395 us-gaap:RealEstateFundsMember us-gaap:LimitedPartnerMember 2019-12-31 0001267395 us-gaap:LetterOfCreditMember 2019-12-31 0001267395 us-gaap:RealEstateFundsMember us-gaap:LimitedPartnerMember 2018-12-31 0001267395 ahl:ThirdPartyMember 2018-12-31 0001267395 ahl:ThirdPartyMember 2019-12-31 0001267395 srt:AffiliatedEntityMember 2019-12-31 0001267395 ahl:SingaporeTrustFundMember 2018-12-31 0001267395 ahl:UsSurplusLinesTrustFundMember 2018-12-31 0001267395 ahl:UsMultiBeneficiaryTrustFundMember 2019-12-31 0001267395 ahl:AustralianTrustFundMember 2018-12-31 0001267395 ahl:CanadianTrustFundMember 2019-12-31 0001267395 ahl:CanadianTrustFundMember 2018-12-31 0001267395 ahl:AspenBermudaMember 2018-12-31 0001267395 ahl:SwissTrustFundMember 2019-12-31 0001267395 ahl:AspenBermudaMember 2019-12-31 0001267395 ahl:AustralianTrustFundMember 2019-12-31 0001267395 ahl:UsSurplusLinesTrustFundMember 2019-12-31 0001267395 ahl:UsMultiBeneficiaryTrustFundMember 2018-12-31 0001267395 ahl:SwissTrustFundMember 2018-12-31 0001267395 ahl:SingaporeTrustFundMember 2019-12-31 0001267395 srt:AMBestAPlusRatingMember srt:StandardPoorsAPlusRatingMember ahl:EverestReMember 2018-01-01 2018-12-31 0001267395 srt:AMBestAPlusRatingMember srt:StandardPoorsAPlusRatingMember ahl:MSADGroupMember 2019-01-01 2019-12-31 0001267395 srt:AMBestAPlusRatingMember srt:StandardPoorsAAMinusRatingMember ahl:MunichReMember 2019-01-01 2019-12-31 0001267395 srt:AMBestAPlusRatingMember srt:StandardPoorsAAMinusRatingMember ahl:MunichReMember 2018-01-01 2018-12-31 0001267395 srt:AMBestAPlusRatingMember srt:StandardPoorsAPlusRatingMember ahl:EverestReMember 2019-01-01 2019-12-31 0001267395 srt:AMBestAPlusRatingMember srt:StandardPoorsAPlusRatingMember ahl:MSADGroupMember 2018-01-01 2018-12-31 0001267395 ahl:OthersMember 2019-01-01 2019-12-31 0001267395 ahl:WillisGroupHoldingsLtdMember 2017-01-01 2017-12-31 0001267395 ahl:OthersMember 2017-01-01 2017-12-31 0001267395 ahl:OthersMember 2018-01-01 2018-12-31 0001267395 ahl:WillisGroupHoldingsLtdMember 2018-01-01 2018-12-31 0001267395 ahl:AonCorporationMember 2017-01-01 2017-12-31 0001267395 ahl:MarshAndMcLennanCompaniesIncMember 2018-01-01 2018-12-31 0001267395 ahl:AonCorporationMember 2019-01-01 2019-12-31 0001267395 ahl:MarshAndMcLennanCompaniesIncMember 2019-01-01 2019-12-31 0001267395 ahl:WillisGroupHoldingsLtdMember 2019-01-01 2019-12-31 0001267395 ahl:AonCorporationMember 2018-01-01 2018-12-31 0001267395 ahl:MarshAndMcLennanCompaniesIncMember 2017-01-01 2017-12-31 0001267395 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetInvestmentGainLossIncludingPortionAttributableToNoncontrollingInterestMember 2018-01-01 2018-12-31 0001267395 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember 2019-01-01 2019-12-31 0001267395 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetGainLossFromCashFlowHedgesIncludingPortionAttributableToNoncontrollingInterestMember 2018-01-01 2018-12-31 0001267395 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetInvestmentGainLossIncludingPortionAttributableToNoncontrollingInterestMember 2019-01-01 2019-12-31 0001267395 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetGainLossFromCashFlowHedgesIncludingPortionAttributableToNoncontrollingInterestMember 2019-01-01 2019-12-31 0001267395 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember 2018-01-01 2018-12-31 0001267395 us-gaap:LondonInterbankOfferedRateLIBORMember 2019-01-01 2019-12-31 0001267395 us-gaap:SeniorNotesMember 2019-01-01 2019-12-31 0001267395 2017-03-27 2017-03-27 0001267395 us-gaap:SeniorNotesMember 2013-11-13 2013-11-13 0001267395 us-gaap:LetterOfCreditMember ahl:CitibankEuropeplcMember 2016-06-30 0001267395 us-gaap:SeniorNotesMember 2013-11-13 0001267395 us-gaap:SeniorNotesMember 2010-12-15 0001267395 us-gaap:SeniorNotesMember 2010-12-15 2010-12-15 0001267395 2017-03-27 0001267395 ahl:CitibankEuropeMember 2019-01-01 2019-12-31 0001267395 ahl:CitibankEuropeMember 2018-01-01 2018-12-31 0001267395 ahl:EnstarMember srt:MaximumMember us-gaap:SubsequentEventMember 2020-03-02 2020-03-02 0001267395 ahl:EnstarMember us-gaap:SubsequentEventMember 2020-03-02 0001267395 ahl:EnstarMember srt:MinimumMember us-gaap:SubsequentEventMember 2020-03-02 2020-03-02 0001267395 ahl:EnstarMember us-gaap:SubsequentEventMember 2020-01-01 0001267395 ahl:EnstarMember us-gaap:SubsequentEventMember 2020-01-01 2020-01-01 0001267395 srt:ParentCompanyMember us-gaap:SeriesDPreferredStockMember 2018-12-31 0001267395 srt:ParentCompanyMember us-gaap:SeriesEPreferredStockMember 2019-12-31 0001267395 srt:ParentCompanyMember us-gaap:SeriesEPreferredStockMember 2018-12-31 0001267395 srt:ParentCompanyMember us-gaap:SeriesFPreferredStockMember 2019-12-31 0001267395 srt:ParentCompanyMember us-gaap:SeriesFPreferredStockMember 2018-12-31 0001267395 srt:ParentCompanyMember us-gaap:SeriesDPreferredStockMember 2019-12-31 0001267395 srt:ParentCompanyMember 2017-01-01 2017-12-31 0001267395 srt:ParentCompanyMember us-gaap:ParentMember 2018-01-01 2018-12-31 0001267395 srt:ParentCompanyMember us-gaap:ParentMember 2017-01-01 2017-12-31 0001267395 srt:ParentCompanyMember 2016-12-31 0001267395 us-gaap:ParentMember 2017-01-01 2017-12-31 0001267395 us-gaap:ParentMember 2018-01-01 2018-12-31 0001267395 srt:ParentCompanyMember ahl:MVIMember 2018-01-01 2018-12-31 0001267395 srt:ParentCompanyMember ahl:MVIMember 2019-01-01 2019-12-31 0001267395 us-gaap:ParentMember 2019-01-01 2019-12-31 0001267395 srt:ParentCompanyMember us-gaap:ParentMember 2019-01-01 2019-12-31 0001267395 srt:ParentCompanyMember ahl:MVIMember 2017-01-01 2017-12-31 0001267395 us-gaap:PremiumsReceivableMember 2018-01-01 2018-12-31 0001267395 ahl:ReinsuranceMember 2019-01-01 2019-12-31 0001267395 us-gaap:PremiumsReceivableMember 2019-01-01 2019-12-31 0001267395 ahl:ReinsuranceMember 2018-01-01 2018-12-31 0001267395 us-gaap:PremiumsReceivableMember 2017-12-31 0001267395 ahl:ReinsuranceMember 2018-12-31 0001267395 us-gaap:PremiumsReceivableMember 2016-12-31 0001267395 ahl:ReinsuranceMember 2017-12-31 0001267395 us-gaap:PremiumsReceivableMember 2018-12-31 0001267395 ahl:ReinsuranceMember 2017-01-01 2017-12-31 0001267395 ahl:ReinsuranceMember 2019-12-31 0001267395 us-gaap:PremiumsReceivableMember 2017-01-01 2017-12-31 0001267395 ahl:ReinsuranceMember 2016-12-31 0001267395 us-gaap:PremiumsReceivableMember 2019-12-31 iso4217:USD xbrli:pure ahl:segement xbrli:shares ahl:period iso4217:USD xbrli:shares ahl:security ahl:Investment ahl:Security ahl:Integer iso4217:USD ahl:Investment iso4217:GBP iso4217:AUD iso4217:CHF iso4217:CAD iso4217:SGD 300000 4300000 525000000 775000000 21600000 1631000 745434 745000 AAA AA+ AA+ AAA AA+ -2000000 -4800000 13600000 AA- AA- AA- AA- AA- AA- AA- AA -14800000 -81300000 164900000 0 0 0.6 0 0 0 0 0 0 0 0 800000 -2500000 2500000 800000 470000000 26900000 69100000 36200000 28600000 37900000 0 36200000 0 36200000 29400000 0 28600000 0 28600000 -200000 -200000 2100000 -8000000 8000000 0 0 0 0 8000000 0.564 0.544 1469000 700000 0 0 800000 58300000 56800000 54500000 0.19 0.17 0.20 1000000 50000000.0 0 0 4600000 4600000 0 0 0 0 325000000 325000000 3500000 400500000 165000000 235500000 371600000 110700000 260900000 412700000 147800000 264900000 0 100000 3300000 21500000 581900000 24900000 11100000 16800000 15500000 15300000 0 0 0 19900000 600000 0 0.2 771100000 635400000 6100000 6700000 0.35156 0.00001 0 801900000 772100000 351000000 788400000 782000000 404000000 0.25 28200000 9900000 900000 4400000 1000000 0 6000000 300000 -590700000 -371300000 -415100000 0.768 0 0 7700000 2935200000 2687900000 2811400000 2.2 2.4 16600000 -5900000 -73800000 0 0 0 0 0 0 0 0 0 0 491900000 21200000 -4400000 4400000 5500000 1100000 -3100000 3100000 3900000 800000 15000000 800000 -28100000 27500000 -63900000 59000000 -70600000 -44000000 100000 8783300000 8689500000 P5Y 0 0 0 0 -4600000 0 0.058 0.032 0.036 0.082 0.014 6739400000 6771400000 122000 636000 -125500000 0 0 -125500000 100000000 444200000 444200000 0.25 0.25 2323100000.0 1100000 0 1994700000 878300000 1116400000 1573000000 646000000 927000000 1679700000 761800000 917900000 0 111100000 20000000 -9900000 -5500000 -400000 323000000 224500000 174600000 2000000 700000 -9600000 120500000 -64700000 86200000 6 0.0015144558 6787880 0 10000 0 15200000 37500000 22200000 39000000 103400000 12300000 11300000 2 1 2039 2026 1900000 0 8600000 5500000 2400000 1400000 1100000 130700000 130800000 182700000 0 8600000 5500000 500000 0 0 0 0 287300000 1.2 0.02 0.35 1 1 0.1 0.0595 0.05625 0 0.0595 0.05625 0 0.0595 0.05625 0.05625 0.0595 0.05625 0.05625 8400000 8700000 13100000 21500000 152000 45000 3209200000 1757400000 1451800000 3534400000 1940500000 1593900000 3422400000 1927500000 1494900000 15700000 1.000 0.164 0.160 0.545 0.131 1.000 0.158 0.158 0.560 0.124 1.000 0.134 0.136 0.627 0.103 59474085 59743156 0 0 279700000 0 0 0 111700000 8700000 125700000 30900000 2700000 279700000 279700000 0 279200000 316300000 505600000 0 189500000 113200000 159000000 0 9800000 131300000 16500000 0 -7400000 4100000 -7500000 6000000 6100000 1311400000 647800000 1374400000 427700000 560700000 1515200000 2077600000 300000000 1497800000 1817500000 4800000000 0.15 0.0375 0.25 P60D P12M P8Y P9Y P8Y 0.9 P30D 100000000 4419200000 2511700000 1033900000 771100000 4268300000 2766600000 754900000 635400000 3500000 1201200000 508000000 545900000 627200000 640100000 579900000 186600000 9500000 79200000 227400000 105600000 117600000 0.15 39752.6646026832 6993 0 2600000 1900000 200000 0 1600000 100000 6400000 6300000 0 2400000 11600000 7400000 900000 100000 1800000 0 200000 700000 0 24900000 24200000 300000 200000 0 0 16600000 5200000 1100000 100000 500000 1800000 25300000 23500000 0 1700000 100000 100000 0 0 100000 800000 200000 200000 0 3000000 2000000 0 0 0 -2400000 2200000 900000 0 0 -943700000 -575800000 -236300000 false --12-31 true FY 2019 2019-12-31 false false 20-F 0001267395 60395839 Yes false Non-accelerated Filer Yes ASPEN INSURANCE HOLDINGS LTD false No No 400000 400000 684500000 865700000 700000 2200000 18100000 100000 2700000 247400000 47300000 220800000 7200000 -66800000 84500000 -55400000 -80200000 -55900000 -121900000 -121900000 8600000 8600000 0.174 0.150 0.195 0.168 0.116 0.208 0.180 0.142 0.211 967500000 967500000 1201700000 1201700000 21600000 800000 800000 1600000 400000 500000 0 300000 400000 1500000 100000 600000 0 200000 600000 12532900000 3232500000 12580500000 3095000000 503200000 513100000 1336400000 209300000 152700000 135900000 9000000 1112400000 198800000 1395200000 226900000 155400000 148900000 8400000 846200000 215500000 1451800000 1593900000 1494900000 1548500000 1495700000 1485500000 26300000 0 7800000 200000 3600000 6500000 1300000 100000 6800000 0 26300000 116800000 0 0 54800000 500000 4500000 21900000 2900000 900000 31300000 0 116800000 77900000 100000 40500000 200000 800000 19000000 800000 400000 16100000 0 77900000 3800000 200000 0 600000 100000 400000 1100000 0 0 1400000 0 3800000 5282300000 17400000 2238900000 4239800000 93200000 399800000 1025100000 46700000 47700000 1413500000 105600000 5387900000 4845200000 6700000 200000 1905600000 3786100000 86100000 324700000 1052200000 47800000 38700000 1383200000 117600000 4962800000 17400000 5282300000 1025100000 6700000 200000 4845200000 1052200000 58800000 100000 25300000 200000 500000 16400000 700000 200000 15400000 58800000 0 1200000 0 0 0 0 0 800000 0 0 400000 1200000 0 77900000 100000 40500000 200000 800000 19000000 800000 400000 16100000 77900000 0 3800000 200000 0 600000 100000 400000 1100000 0 0 1400000 3800000 0 3682000000 17100000 1761300000 40300000 155000000 693000000 28100000 31900000 920800000 3647500000 34500000 833000000 6500000 200000 204800000 31800000 49200000 218100000 3700000 9000000 280200000 803500000 29500000 19100000 0 15200000 0 300000 2600000 100000 200000 700000 19100000 0 2600000 200000 0 600000 100000 400000 300000 0 0 1000000 2600000 0 1560900000 6300000 999100000 14500000 64000000 245700000 3100000 13500000 180200000 1526400000 34500000 582500000 6500000 0 167700000 31800000 48600000 149700000 3700000 3000000 142000000 553000000 29500000 2121100000 10800000 762200000 25800000 91000000 447300000 25000000 18400000 740600000 2121100000 0 250500000 0 200000 37100000 0 600000 68400000 0 6000000 138200000 250500000 0 1047900000 864100000 1028300000 896300000 2605700000 2230300000 2582000000 2269300000 121900000 119000000 127000000 138300000 464300000 572700000 463500000 574600000 5230700000 17300000 2206200000 4200800000 5230700000 93200000 402600000 1012600000 47200000 47400000 1404200000 105600000 5230700000 5336300000 105600000 4958200000 6500000 200000 1959800000 3878500000 4958200000 86500000 328800000 1073000000 50700000 39600000 1413100000 117600000 495820000