XML 38 R44.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Note 4 - Fair Value of Financial Instruments Fair Value Assets Liabilities by Hierarchy Level (Details) (USD $) | Mar. 31, 2015 | Dec. 31, 2014 | Mar. 31, 2014
--- | --- | --- | ---
Carrying (Reported) Amount, Fair Value Disclosure [Member] |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Other Invested Assets, Carrying Amount | $ 14,000,000 rdn_OtherInvestedAssetsCarryingAmount / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember |  | $ 14,600,000 rdn_OtherInvestedAssetsCarryingAmount / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember |  |
Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 3,607,600,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [1] | 3,614,700,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] |
Total Assets at Fair Value | 3,607,600,000 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 3,614,700,000 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount | 0 us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |  | 0 us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount | 0 us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |  |  | 0 us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember
US government and agency securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 633,600,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USTreasuryAndGovernmentMember |  | 839,900,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USTreasuryAndGovernmentMember |  |
State and municipal obligations | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 353,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 362,800,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  |
Money market instruments | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 601,300,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_MoneyMarketFundsMember |  | 600,300,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_MoneyMarketFundsMember |  |
Corporate bonds and notes | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 1,115,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CorporateDebtSecuritiesMember |  | 992,800,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CorporateDebtSecuritiesMember |  |
RMBS | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 128,100,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 132,300,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |
CMBS | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 247,900,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 246,800,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |
Other ABS | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 177,600,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_AssetBackedSecuritiesMember |  | 185,500,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_AssetBackedSecuritiesMember |  |
Foreign government securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 35,300,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  | 37,700,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  |
Equity securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 214,800,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquitySecuritiesMember | [3] | 215,600,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquitySecuritiesMember | [3] |
Other investments | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 101,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_OtherInvestmentsMember | [4] | 1,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_OtherInvestmentsMember | [5] |
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 1,394,500,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [1] | 1,601,200,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] |
Total Assets at Fair Value | 1,394,500,000 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 1,601,200,000 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |
Assets Held-for-sale, Long Lived, Fair Value Disclosure | 502,100,000 us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 495,100,000 us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |
Fair Value, Inputs, Level 1 | US government and agency securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 630,600,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USTreasuryAndGovernmentMember |  | 836,900,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USTreasuryAndGovernmentMember |  |
Fair Value, Inputs, Level 1 | State and municipal obligations | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  |
Fair Value, Inputs, Level 1 | Money market instruments | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 601,300,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_MoneyMarketFundsMember |  | 600,300,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_MoneyMarketFundsMember |  |
Fair Value, Inputs, Level 1 | Corporate bonds and notes | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CorporateDebtSecuritiesMember |  | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CorporateDebtSecuritiesMember |  |
Fair Value, Inputs, Level 1 | RMBS | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |
Fair Value, Inputs, Level 1 | CMBS | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |
Fair Value, Inputs, Level 1 | Other ABS | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_AssetBackedSecuritiesMember |  |
Fair Value, Inputs, Level 1 | Foreign government securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  |
Fair Value, Inputs, Level 1 | Equity securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 162,600,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquitySecuritiesMember | [3] | 164,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquitySecuritiesMember | [3] |
Fair Value, Inputs, Level 1 | Other investments | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_OtherInvestmentsMember | [4] | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_OtherInvestmentsMember | [5] |
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 2,213,100,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [1] | 2,013,500,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember | [2] |
Total Assets at Fair Value | 2,213,100,000 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 2,013,500,000 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |
Assets Held-for-sale, Long Lived, Fair Value Disclosure | 838,000,000 us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 839,200,000 us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |
Fair Value, Inputs, Level 2 | US government and agency securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 3,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USTreasuryAndGovernmentMember |  | 3,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USTreasuryAndGovernmentMember |  |
Fair Value, Inputs, Level 2 | State and municipal obligations | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 353,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  | 362,800,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |  |
Fair Value, Inputs, Level 2 | Money market instruments | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_MoneyMarketFundsMember |  | 0 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_MoneyMarketFundsMember |  |
Fair Value, Inputs, Level 2 | Corporate bonds and notes | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 1,115,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CorporateDebtSecuritiesMember |  | 992,800,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CorporateDebtSecuritiesMember |  |
Fair Value, Inputs, Level 2 | RMBS | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 128,100,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  | 132,300,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |  |
Fair Value, Inputs, Level 2 | CMBS | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 247,900,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  | 246,800,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |  |
Fair Value, Inputs, Level 2 | Other ABS | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 177,600,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_AssetBackedSecuritiesMember |  | 185,500,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_AssetBackedSecuritiesMember |  |
Fair Value, Inputs, Level 2 | Foreign government securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 35,300,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  | 37,700,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  |
Fair Value, Inputs, Level 2 | Equity securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 52,200,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquitySecuritiesMember | [3] | 51,600,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_EquitySecuritiesMember | [3] |
Fair Value, Inputs, Level 2 | Other investments | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 101,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_OtherInvestmentsMember | [4] | 1,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_OtherInvestmentsMember | [5] |
Fair Value, Inputs, Level 2 | Trust Preferred Securities [Member] | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 100,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = us-gaap_CommercialPaperMember |  |  |  |
Fair Value, Inputs, Level 2 | Short Term CDs | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value | 1,000,000 us-gaap_InvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_InvestmentTypeAxis = rdn_ShortTermCdsMember |  |  |  |
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Assets at Fair Value | 0 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 0 us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |
Assets Held-for-sale, Long Lived, Fair Value Disclosure | 102,800,000 us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 102,600,000 us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |
Variable Interest Entity Debt |  |  | $ 3,800,000 rdn_VariableInterestEntityDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |
Total Level III Liabilities |  |  | 100.00%rdn_TotalLevelIIILiabilitiesasaPercentageofTotalLiabilitiesMeasuredatFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  |
[1] | Does not include certain other invested assets ($14.0 million), primarily invested in limited partnerships, accounted for as cost-method investments and not measured at fair value. Also excludes investments classified as assets held for sale of $502.1 million, $838.0 million and $102.8 million, with fair values categorized in Level I, Level II and Level III, respectively.
[2] | Does not include certain other invested assets ($14.6 million), primarily invested in limited partnerships, accounted for as cost-method investments and not measured at fair value. Also excludes investments classified as assets held for sale of $495.1 million, $839.2 million and $102.6 million, with fair values categorized in Level I, Level II and Level III, respectively.
[3] | Comprising broadly diversified domestic equity mutual funds and certain common stocks included within Level I and various preferred stocks invested across numerous companies and industries included within Level II.
[4] | Comprising short-term certificates of deposit ($1.0 million) and short-term commercial paper ($100.0 million) included within Level II.
[5] | Comprising short-term certificates of deposit.

X
- Definition Aggregate carrying amount, as of the balance sheet date, of other invested assets not separately disclosed in the balance sheet. + References No definition available. + Details
Name: | rdn_OtherInvestedAssetsCarryingAmount
Namespace Prefix: | rdn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Total Level III Liabilities is the percentage of total level III liabilities to the total liabilities measured at fair value + References No definition available. + Details
Name: | rdn_TotalLevelIIILiabilitiesasaPercentageofTotalLiabilitiesMeasuredatFairValue
Namespace Prefix: | rdn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition This concept represents the amount of debt related to Variable Interest Entities that have been consolidated as the entity is the primary beneficiary of that VIE or has the ability to control its actions. + References No definition available. + Details
Name: | rdn_VariableInterestEntityDebt
Namespace Prefix: | rdn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of assets classified as held for sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19190-110258 + Details
Name: | us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bb) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bb) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Available-for-Sale Securities -URI http://asc.fasb.org/extlink&oid=6505594 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Subparagraph a, f, g -Article 7 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560 + Details
Name: | us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_OtherInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |