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Fair Value Measurements (Narrative) (Details) (USD $)
Share data in Millions, except Per Share data, unless otherwise specified
12 Months Ended 0 Months Ended 3 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Mar. 17, 2010
Oct. 31, 2013
Dec. 31, 2014
Sep. 30, 2013
Jun. 30, 2014
Jul. 18, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Fair value transfers out of level 3 $ 24,644,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 $ 85,555,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3              
Total other assets and (liabilities) (13,908,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis (8,233,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis       (13,908,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis      
Net unrealized gains (losses) recognized in earnings (1,393,000)us-gaap_UnrealizedGainLossOnInvestments 75,789,000us-gaap_UnrealizedGainLossOnInvestments 38,207,000us-gaap_UnrealizedGainLossOnInvestments            
Other Investments | Net investment income                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Net unrealized gains (losses) recognized in earnings (1,400,000)us-gaap_UnrealizedGainLossOnInvestments
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_OtherInvestmentsMember
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_InvestmentIncomeMember
75,800,000us-gaap_UnrealizedGainLossOnInvestments
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_OtherInvestmentsMember
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_InvestmentIncomeMember
38,200,000us-gaap_UnrealizedGainLossOnInvestments
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_OtherInvestmentsMember
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_InvestmentIncomeMember
           
Other Assets and Liabilities | Other income (loss)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Net unrealized gains (losses) recognized in earnings 0us-gaap_UnrealizedGainLossOnInvestments
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= rnr_OtherAssetsAndLiabilitiesMember
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_OtherOperatingIncomeExpenseMember
0us-gaap_UnrealizedGainLossOnInvestments
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= rnr_OtherAssetsAndLiabilitiesMember
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_OtherOperatingIncomeExpenseMember
(3,200,000)us-gaap_UnrealizedGainLossOnInvestments
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= rnr_OtherAssetsAndLiabilitiesMember
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_OtherOperatingIncomeExpenseMember
           
5.75% Senior Notes Due March 15, 2020 | RenRe North America Holdings Inc.                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
5.75% Senior Notes Due March 15, 2020       250,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= rnr_FivePointSevenFivePercentageSeniorNotesDueMarchFifteenTwoThousandAndTwentyMember
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
         
Senior notes interest rate       5.75%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= rnr_FivePointSevenFivePercentageSeniorNotesDueMarchFifteenTwoThousandAndTwentyMember
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
         
Debt instrument maturity date       March 15, 2020          
Senior Notes, fair value 279,000,000us-gaap_LongTermDebtFairValue
/ us-gaap_DebtInstrumentAxis
= rnr_FivePointSevenFivePercentageSeniorNotesDueMarchFifteenTwoThousandAndTwentyMember
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
273,900,000us-gaap_LongTermDebtFairValue
/ us-gaap_DebtInstrumentAxis
= rnr_FivePointSevenFivePercentageSeniorNotesDueMarchFifteenTwoThousandAndTwentyMember
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
      279,000,000us-gaap_LongTermDebtFairValue
/ us-gaap_DebtInstrumentAxis
= rnr_FivePointSevenFivePercentageSeniorNotesDueMarchFifteenTwoThousandAndTwentyMember
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
     
Quoted Prices In Active Markets For Identical Assets (Level 1)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Total other assets and (liabilities) (569,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
823,000rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
      (569,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
     
Significant Other Observable Inputs (Level 2)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Total other assets and (liabilities) (4,405,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
(6,566,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
      (4,405,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
     
Significant Other Observable Inputs (Level 2) | Cash Settled Restricted Stock Unit                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Total other assets and (liabilities) (11,500,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementBasisAxis
= us-gaap_RestrictedStockUnitsRSUMember
        (11,500,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementBasisAxis
= us-gaap_RestrictedStockUnitsRSUMember
     
Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Assets, fair value 310,544,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
        310,544,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
     
Total other assets and (liabilities) (8,934,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
(2,490,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
      (8,934,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
     
U.S. treasuries                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 1.00%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
0.80%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
      1.00%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
     
Agencies                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 1.20%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
1.30%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
      1.20%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
     
Non-U.S. government (Sovereign Debt)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 1.10%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember
1.30%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember
      1.10%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember
     
Non-U.S. government-backed corporate                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 1.10%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= rnr_NonUSGovernmentBackedCorporateDebtSecuritiesMember
1.10%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= rnr_NonUSGovernmentBackedCorporateDebtSecuritiesMember
      1.10%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= rnr_NonUSGovernmentBackedCorporateDebtSecuritiesMember
     
Corporate                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 3.20%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
2.70%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
      3.20%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
     
Agency mortgage-backed                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 2.30%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
2.90%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
      2.30%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
     
Weighted average life 5 years 7 months 6 days 6 years 2 months 12 days              
Non-agency prime residential mortgage-backed                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 3.40%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= rnr_NonAgencyPrimeResidentialMortgageBackedSecuritiesMember
3.70%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= rnr_NonAgencyPrimeResidentialMortgageBackedSecuritiesMember
      3.40%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= rnr_NonAgencyPrimeResidentialMortgageBackedSecuritiesMember
     
Weighted average life 4 years 1 month 6 days 4 years 4 months 24 days              
AltA non-agency mortgage-backed                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 4.30%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= rnr_AltaNonAgencyMortgageBackedSecuritiesMember
4.70%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= rnr_AltaNonAgencyMortgageBackedSecuritiesMember
      4.30%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= rnr_AltaNonAgencyMortgageBackedSecuritiesMember
     
Weighted average life 5 years 4 years              
Commercial mortgage-backed                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 2.10%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember
2.10%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember
      2.10%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember
     
Weighted average life 3 years 6 months 0 days 3 years 3 months 18 days              
Asset-backed                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Weighted average effective yield 1.50%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember
2.00%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember
      1.50%rnr_WeightedAverageEffectiveYield
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember
     
Weighted average life 2 years 6 months 3 years 6 months              
Senior secured bank loan funds                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Investment in closed end fund 19,300,000rnr_InvestmentInClosedEndFund
/ us-gaap_InvestmentTypeAxis
= rnr_SeniorSecuredBankLoanFundsMember
        19,300,000rnr_InvestmentInClosedEndFund
/ us-gaap_InvestmentTypeAxis
= rnr_SeniorSecuredBankLoanFundsMember
     
Hedge funds                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Hedge fund side pocket investments 2,600,000rnr_NonredeemableSidePocketInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_HedgeFundsMember
        2,600,000rnr_NonredeemableSidePocketInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_HedgeFundsMember
     
Fixed maturity investments                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Fair value transfers out of level 3 24,644,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_FixedMaturitiesMember
0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_FixedMaturitiesMember
             
Fixed maturity investments | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Assets, fair value 15,660,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_FixedMaturitiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
        15,660,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_FixedMaturitiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
     
Miscellaneous Investments | Internal Valuation Model Valuation Technique | Significant Unobservable Inputs (Level 3) | Essent Group Ltd.                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Assets, fair value             48,000,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_MiscellaneousInvestmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ dei_LegalEntityAxis
= rnr_EssentGroupLtd.Member
/ us-gaap_ValuationTechniqueAxis
= rnr_InternalValuationModelValuationTechniqueMember
   
Trading Securities | Quoted Prices In Active Markets For Identical Assets (Level 1) | Essent Group Ltd.                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Fair value transfers out of level 3         85,600,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_TradingAccountAssetsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ dei_LegalEntityAxis
= rnr_EssentGroupLtd.Member
       
Equity investment, price per share         $ 17.00us-gaap_SharePrice
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_TradingAccountAssetsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ dei_LegalEntityAxis
= rnr_EssentGroupLtd.Member
       
Corporate | Discounted Cash Flow Valuation Technique | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Assets, fair value 15,700,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_DiscountedCashFlowValuationTechniqueMember
        15,700,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_DiscountedCashFlowValuationTechniqueMember
     
Private equity partnerships | Net Asset Valuation Technique | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Assets, fair value 281,900,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_NetAssetValuationTechniqueMember
        281,900,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_NetAssetValuationTechniqueMember
     
Assumed And Ceded Re Insurance Contracts Member | Internal Valuation Model Valuation Technique | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Total other assets and (liabilities) (8,744,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByAssetClassAxis
= rnr_AssumedAndCededReInsuranceContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_InternalValuationModelValuationTechniqueMember
        (8,744,000)rnr_OtherAssetsAndliabilitiesMeasuredonRecurringBasis
/ us-gaap_FairValueByAssetClassAxis
= rnr_AssumedAndCededReInsuranceContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_InternalValuationModelValuationTechniqueMember
     
Liabilities, fair value 8,700,000us-gaap_LiabilitiesFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= rnr_AssumedAndCededReInsuranceContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_InternalValuationModelValuationTechniqueMember
        8,700,000us-gaap_LiabilitiesFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= rnr_AssumedAndCededReInsuranceContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_InternalValuationModelValuationTechniqueMember
     
Weather Contract | Internal Valuation Model Valuation Technique | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Liabilities, fair value 200,000us-gaap_LiabilitiesFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= rnr_WeatherContractMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_InternalValuationModelValuationTechniqueMember
        200,000us-gaap_LiabilitiesFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= rnr_WeatherContractMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_ValuationTechniqueAxis
= rnr_InternalValuationModelValuationTechniqueMember
     
Other Investments                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Fair value transfers out of level 3 0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_OtherInvestmentsMember
85,555,000us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_OtherInvestmentsMember
             
Other Investments | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Assets, fair value 303,818,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_OtherInvestmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
        303,818,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_OtherInvestmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
     
Weighted Average or Actual | Corporate | Discounted Cash Flow Valuation Technique | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Dividend rate 6.50%us-gaap_FairValueAssumptionsExpectedDividendRate
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_RangeAxis
= rnr_WeightedAverageOrActualMember
/ us-gaap_ValuationTechniqueAxis
= rnr_DiscountedCashFlowValuationTechniqueMember
               
Liquidity discount 1.00%us-gaap_FairValueInputsDiscountForLackOfMarketability
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_RangeAxis
= rnr_WeightedAverageOrActualMember
/ us-gaap_ValuationTechniqueAxis
= rnr_DiscountedCashFlowValuationTechniqueMember
               
Risk-free rate 0.50%us-gaap_FairValueAssumptionsRiskFreeInterestRate
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_RangeAxis
= rnr_WeightedAverageOrActualMember
/ us-gaap_ValuationTechniqueAxis
= rnr_DiscountedCashFlowValuationTechniqueMember
               
Credit spread 0.80%us-gaap_FairValueInputsEntityCreditRisk
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_CorporateDebtSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_RangeAxis
= rnr_WeightedAverageOrActualMember
/ us-gaap_ValuationTechniqueAxis
= rnr_DiscountedCashFlowValuationTechniqueMember
               
Weighted Average or Actual | Private equity partnerships | Net Asset Valuation Technique | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Estimated performance           0.10%rnr_FairValueInputsEstimatedPerformance
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_RangeAxis
= rnr_WeightedAverageOrActualMember
/ us-gaap_ValuationTechniqueAxis
= rnr_NetAssetValuationTechniqueMember
     
Minimum | Private equity partnerships                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Liquidating period 7 years                
Minimum | Senior secured bank loan funds                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Liquidating period 4 years                
Minimum | Private equity partnerships | Net Asset Valuation Technique | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Estimated performance           (42.10%)rnr_FairValueInputsEstimatedPerformance
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= rnr_NetAssetValuationTechniqueMember
     
Maximum | Private equity partnerships                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Liquidating period 10 years                
Maximum | Senior secured bank loan funds                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Liquidating period 5 years                
Maximum | Private equity partnerships | Net Asset Valuation Technique | Significant Unobservable Inputs (Level 3)                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Estimated performance           17.00%rnr_FairValueInputsEstimatedPerformance
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_PrivateEquityFundsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= rnr_NetAssetValuationTechniqueMember
     
Convertible preferred stock | Trupanion                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Equity investment, fair value               30,200,000us-gaap_InvestmentOwnedAtFairValue
/ dei_LegalEntityAxis
= rnr_TrupanionMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_ConvertiblePreferredStockMember
 
Common stock | Trupanion                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Equity investment, fair value 17,100,000us-gaap_InvestmentOwnedAtFairValue
/ dei_LegalEntityAxis
= rnr_TrupanionMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
        17,100,000us-gaap_InvestmentOwnedAtFairValue
/ dei_LegalEntityAxis
= rnr_TrupanionMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
    24,600,000us-gaap_InvestmentOwnedAtFairValue
/ dei_LegalEntityAxis
= rnr_TrupanionMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
Equity investment, number of shares                 2.5us-gaap_InvestmentOwnedBalanceShares
/ dei_LegalEntityAxis
= rnr_TrupanionMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
Equity investment, price per share                 $ 10.00us-gaap_SharePrice
/ dei_LegalEntityAxis
= rnr_TrupanionMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
Common stock | Essent Group Ltd.                  
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]                  
Equity investment, fair value $ 120,000,000us-gaap_InvestmentOwnedAtFairValue
/ dei_LegalEntityAxis
= rnr_EssentGroupLtd.Member
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
        120,000,000us-gaap_InvestmentOwnedAtFairValue
/ dei_LegalEntityAxis
= rnr_EssentGroupLtd.Member
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember