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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 | $ 24,644,000 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 | $ 85,555,000 us-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 | 75,789,000 us-gaap_UnrealizedGainLossOnInvestments | 38,207,000 us-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 | 75,800,000 us-gaap_UnrealizedGainLossOnInvestments / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_OtherInvestmentsMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember | 38,200,000 us-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 | 0 us-gaap_UnrealizedGainLossOnInvestments / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = rnr_OtherAssetsAndLiabilitiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherOperatingIncomeExpenseMember | 0 us-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 |  |  |  | 250,000,000 us-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 | 279,000,000 us-gaap_LongTermDebtFairValue / us-gaap_DebtInstrumentAxis = rnr_FivePointSevenFivePercentageSeniorNotesDueMarchFifteenTwoThousandAndTwentyMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember | 273,900,000 us-gaap_LongTermDebtFairValue / us-gaap_DebtInstrumentAxis = rnr_FivePointSevenFivePercentageSeniorNotesDueMarchFifteenTwoThousandAndTwentyMember / dei_LegalEntityAxis = us-gaap_SubsidiariesMember |  |  |  | 279,000,000 us-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 | 823,000 rnr_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 | 310,544,000 us-gaap_AssetsFairValueDisclosureRecurring / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |  |  |  |  | 310,544,000 us-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 | 19,300,000 rnr_InvestmentInClosedEndFund / us-gaap_InvestmentTypeAxis = rnr_SeniorSecuredBankLoanFundsMember |  |  |  |  | 19,300,000 rnr_InvestmentInClosedEndFund / us-gaap_InvestmentTypeAxis = rnr_SeniorSecuredBankLoanFundsMember |  |  |
Hedge funds |  |  |  |  |  |  |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |  |  |  |  |  |  |
Hedge fund side pocket investments | 2,600,000 rnr_NonredeemableSidePocketInvestments / us-gaap_InvestmentTypeAxis = us-gaap_HedgeFundsMember |  |  |  |  | 2,600,000 rnr_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 | 24,644,000 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_FixedMaturitiesMember | 0 us-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 | 15,660,000 us-gaap_AssetsFairValueDisclosureRecurring / us-gaap_FairValueByAssetClassAxis = us-gaap_FixedMaturitiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |  |  |  |  | 15,660,000 us-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 |  |  |  |  |  |  | 48,000,000 us-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 |  |  |  |  | 85,600,000 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_TradingAccountAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / dei_LegalEntityAxis = rnr_EssentGroupLtd.Member |  |  |  |
Equity investment, price per share |  |  |  |  | $ 17.00 us-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 | 15,700,000 us-gaap_AssetsFairValueDisclosureRecurring / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_ValuationTechniqueAxis = rnr_DiscountedCashFlowValuationTechniqueMember |  |  |  |  | 15,700,000 us-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 | 281,900,000 us-gaap_AssetsFairValueDisclosureRecurring / us-gaap_FairValueByAssetClassAxis = us-gaap_PrivateEquityFundsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_ValuationTechniqueAxis = rnr_NetAssetValuationTechniqueMember |  |  |  |  | 281,900,000 us-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 | 8,700,000 us-gaap_LiabilitiesFairValueDisclosureRecurring / us-gaap_FairValueByAssetClassAxis = rnr_AssumedAndCededReInsuranceContractsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_ValuationTechniqueAxis = rnr_InternalValuationModelValuationTechniqueMember |  |  |  |  | 8,700,000 us-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 | 200,000 us-gaap_LiabilitiesFairValueDisclosureRecurring / us-gaap_FairValueByAssetClassAxis = rnr_WeatherContractMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_ValuationTechniqueAxis = rnr_InternalValuationModelValuationTechniqueMember |  |  |  |  | 200,000 us-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 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherInvestmentsMember | 85,555,000 us-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 | 303,818,000 us-gaap_AssetsFairValueDisclosureRecurring / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherInvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |  |  |  |  | 303,818,000 us-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 |  |  |  |  |  |  |  | 30,200,000 us-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 | 17,100,000 us-gaap_InvestmentOwnedAtFairValue / dei_LegalEntityAxis = rnr_TrupanionMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonStockMember |  |  |  |  | 17,100,000 us-gaap_InvestmentOwnedAtFairValue / dei_LegalEntityAxis = rnr_TrupanionMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonStockMember |  |  | 24,600,000 us-gaap_InvestmentOwnedAtFairValue / dei_LegalEntityAxis = rnr_TrupanionMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonStockMember
Equity investment, number of shares |  |  |  |  |  |  |  |  | 2.5 us-gaap_InvestmentOwnedBalanceShares / dei_LegalEntityAxis = rnr_TrupanionMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonStockMember
Equity investment, price per share |  |  |  |  |  |  |  |  | $ 10.00 us-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 | $ 120,000,000 us-gaap_InvestmentOwnedAtFairValue / dei_LegalEntityAxis = rnr_EssentGroupLtd.Member / us-gaap_StatementClassOfStockAxis = us-gaap_CommonStockMember |  |  |  |  | 120,000,000 us-gaap_InvestmentOwnedAtFairValue / dei_LegalEntityAxis = rnr_EssentGroupLtd.Member / us-gaap_StatementClassOfStockAxis = us-gaap_CommonStockMember |  |  |

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