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Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2015 | Mar. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2013
Funds Withheld At Interest Embedded Derivatives [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | $ 22,094 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | $ (176,270)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 19,769 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | (99,029)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Funds Withheld At Interest Embedded Derivatives [Member] | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Funds Withheld At Interest Embedded Derivatives [Member] | Investment Related Gains Losses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 77,241 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | (2,325)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 77,241 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Funds Withheld At Interest Embedded Derivatives [Member] | Insurance Claims [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Funds Withheld At Interest Embedded Derivatives [Member] | Interest Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | (2,325)us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Funds Withheld At Interest Embedded Derivatives [Member] | Policy Acquisition Costs And Other Insurance Expenses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |
Funds Withheld At Interest Embedded Derivatives [Member] | Other Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_FundsWithheldAtInterestEmbeddedDerivativesMember |  |  |  |  |
Nonredeemable Preferred Stock [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 7,904 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 4,962 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 88 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 29 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | (29)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 4,962 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 7,992 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Nonredeemable Preferred Stock [Member] | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Nonredeemable Preferred Stock [Member] | Investment Related Gains Losses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Nonredeemable Preferred Stock [Member] | Insurance Claims [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Nonredeemable Preferred Stock [Member] | Interest Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Nonredeemable Preferred Stock [Member] | Policy Acquisition Costs And Other Insurance Expenses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |
Nonredeemable Preferred Stock [Member] | Other Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_NonredeemablePreferredStockMember |  |  |  |  |
Longevity Swap [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 7,727 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 1,821 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 8,602 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Longevity Swap [Member] | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Longevity Swap [Member] | Investment Related Gains Losses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Longevity Swap [Member] | Insurance Claims [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Longevity Swap [Member] | Interest Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Longevity Swap [Member] | Policy Acquisition Costs And Other Insurance Expenses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Longevity Swap [Member] | Other Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | (946)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_LongevitySwapMember |  |  |  |  |
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value | (1,132,270)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | (911,987)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | (1,085,166)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember | (868,726)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss) | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases | (11,644)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember | [1] | (15,193)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySales / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySales / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember | [1] | 19,433 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3 | 18,999 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Investment Related Gains Losses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
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Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | (25,133)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | (23,661)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Insurance Claims [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Interest Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | (48,324)us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | (43,273)us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | (23,840)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Policy Acquisition Costs And Other Insurance Expenses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Other Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_InterestSensitiveContractLiabilitiesEmbeddedDerivativesMember |  |  |  |  |
Mortality Swap [Member] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value | (1,276)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  | (797)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss) | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember | [1] |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySales / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember | [1] |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember | [1] |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersIntoLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3 / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Mortality Swap [Member] | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
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Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Mortality Swap [Member] | Investment Related Gains Losses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Mortality Swap [Member] | Insurance Claims [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Mortality Swap [Member] | Interest Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Mortality Swap [Member] | Policy Acquisition Costs And Other Insurance Expenses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss) | (479)us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings | (479)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings / us-gaap_IncomeStatementLocationAxis = us-gaap_OtherIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = rga_MortalitySwapMember |  |  |  |  |
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 1,310,427 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 1,345,289 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 6,069 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 2,450 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 36,900 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | 79,512 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | (38,747)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | (59,600)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | (51,944)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 6,930 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | (5,609)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | (50,517)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 1,286,979 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 1,291,701 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | (803)us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | (1,062)us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | (803)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | (1,111)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Insurance Claims [Member] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Interest Income [Member] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Residential mortgage-backed securities |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 188,094 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 153,505 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 523 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 2,887 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 11,439 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] | 18,750 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (714)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] | (744)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | (5,719)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] | (6,172)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 600 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 10,563 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | (1,422)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | (1,024)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 192,579 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 177,927 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | (141)us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 52 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | (140)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 56 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Investment Related Gains Losses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | (82)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 106 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Insurance Claims [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Interest Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Policy Acquisition Costs And Other Insurance Expenses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Asset-backed securities |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 572,960 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 471,848 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 3,632 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 5,501 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 40,991 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | [1] | 59,224 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (7,356)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | [1] | (6,612)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | (4,122)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | [1] | (6,315)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 9,055 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 5,948 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | (7,216)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | (29,280)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 609,436 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 502,675 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Asset-backed securities | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 1,399 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 2,050 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 1,419 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 2,057 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Asset-backed securities | Investment Related Gains Losses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 73 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 304 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Asset-backed securities | Insurance Claims [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Asset-backed securities | Interest Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Asset-backed securities | Policy Acquisition Costs And Other Insurance Expenses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 86,746 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 101,785 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | (310)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 3,035 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | (956)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1] | (14,626)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | (5,120)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1] | (279)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 12,828 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 93,869 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 90,373 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 589 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 428 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 594 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 372 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Investment Related Gains Losses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 87 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 86 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_InvestmentRelatedGainsLossesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Insurance Claims [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Interest Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Policy Acquisition Costs And Other Insurance Expenses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = rga_PolicyAcquisitionCostsAndOtherInsuranceExpensesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |  |
Available-for-sale Securities [Member] | US Treasury And Government Member |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 28,529 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |  |  |  |  |
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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember | [1] |  |  |  |
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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |  |  |  |  |
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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 27,756 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Available-for-sale Securities [Member] | US Treasury And Government Member | Insurance Claims [Member] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InsuranceClaimsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) | 25 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 113 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | [1] | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | (29)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | [1] | (64)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | [1] |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | (835)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 41,875 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 43,833 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  |  |
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Investment Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 7 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 12 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InvestmentIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Interest Income [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss) | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 0 us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss / us-gaap_EligibleItemOrGroupForFairValueOptionAxis = us-gaap_AvailableforsaleSecuritiesMember / us-gaap_IncomeStatementLocationAxis = us-gaap_InterestIncomeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Policy Acquisition Costs And Other Insurance Expenses [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |  |  |  |
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[1] | The amount reported within purchases, sales and settlements is the purchase price (for purchases) and the sales/settlement proceeds (for sales and settlements) based upon the actual date purchased or sold/settled. Items purchased and sold/settled in the same period are excluded from the rollforward. The Company had no issuances during the period.

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