 | us-gaap:FixedIncomeInvestmentsMember | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentHoldings |
 | us-gaap:FixedIncomeInvestmentsMember | domain-member | http://fasb.org/us-gaap/role/disclosure/InvestmentHoldings |
 | us-gaap:FixedIncomeInvestmentsMember | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentsSoldNotYetPurchased |
 | us-gaap:FixedIncomeInvestmentsMember | domain-member | http://fasb.org/us-gaap/role/disclosure/InvestmentsSoldNotYetPurchasedInvestmentsSoldNotYetPurchasedTable |
 | us-gaap:FixedIncomeInvestmentsMember | parent-child | http://fasb.org/us-gaap/role/disclosure/SummaryOfInvestmentHoldings |
 | us-gaap:FixedIncomeInvestmentsMember | domain-member | http://fasb.org/us-gaap/role/disclosure/SummaryOfInvestmentHoldings |
 | us-gaap:FixedIncomeInvestmentsMember | parent-child | http://fasb.org/us-gaap/role/disclosure/OtherThanSecuritiesInvestmentHoldings |
 | us-gaap:FixedIncomeInvestmentsMember | domain-member | http://fasb.org/us-gaap/role/disclosure/OtherThanSecuritiesInvestmentHoldingsInvestmentHoldingsOtherThanSecuritiesTable |
 | us-gaap:FixedIncomeInvestmentsMember | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentsFederalTaxNote |
 | us-gaap:FixedIncomeInvestmentsMember | domain-member | http://fasb.org/us-gaap/role/disclosure/InvestmentsFederalTaxNoteFederalIncomeTaxNoteTable |
 | us-gaap:MortgageBackedSecuritiesMember | parent-child | http://fasb.org/us-gaap/role/disclosure/FinancialInstrumentsFairValueDisclosures |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialInstrumentsFairValueDisclosuresFairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationTable |
 | us-gaap:MortgageBackedSecuritiesMember | parent-child | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicing |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingAssumptionForFairValueAsOfBalanceSheetDateOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingAssumptionForFairValueOnSecuritizationDateOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingCustomerSecuritiesForWhichEntityHasRightToSellOrRepledgeTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingFeesEarnedInExchangeForServicingFinancialAssetsTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingFinancialInstrumentsOwnedAndPledgedAsCollateralTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingScheduleOfAssetsAndAssociatedLiabilitiesAccountedForAsSecuredBorrowingsTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingScheduleOfDerecognizedAssetsSecuritizedOrAssetbackedFinancingArrangementAssetsAndAnyOtherFinancialAssetsManagedTogetherTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingSecuritizationFinancialAssetForWhichTransferIsAccountedAsSaleTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingSecuritizedAssetsAndAnyOtherFinancialAssetsManagedTogetherTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingSensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingServicingAssetsAtAmortizedValueTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingServicingAssetsAtFairValueTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingServicingLiabilitiesAtFairValueTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingServicingLiabilityAtAmortizedValueTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingTransferOfCertainFinancialAssetsAccountedForAsSecuredBorrowingsTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/TransfersAndServicingValuationAllowanceForImpairmentOfRecognizedServicingAssetsTable |
 | us-gaap:MortgageBackedSecuritiesMember | parent-child | http://fasb.org/us-gaap/role/disclosure/FinancialServicesBankingAndThrift |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialServicesBankingAndThriftDistributionOfAssetsLiabilitiesAndStockholdersEquityTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialServicesBankingAndThriftFinancingReceivableBeforeAllowanceForCreditLossMaturityTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialServicesBankingAndThriftInterestRateAndInterestDifferentialAnalysisTable |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialServicesBankingAndThriftTransferOfCertainFinancialAssetsAccountedForAsSecuredBorrowingsTable |
 | us-gaap:MortgageBackedSecuritiesMember | parent-child | http://fasb.org/us-gaap/role/disclosure/FinancialServicesBrokersAndDealers |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialServicesBrokersAndDealersCustomerSecuritiesForWhichEntityHasRightToSellOrRepledgeTable |
 | us-gaap:MortgageBackedSecuritiesMember | parent-child | http://fasb.org/us-gaap/role/disclosure/SECScheduleArticle12-15SummaryOfInvestments-OtherThanInvestmentsInRelatedParties |
 | us-gaap:MortgageBackedSecuritiesMember | domain-member | http://fasb.org/us-gaap/role/disclosure/SECScheduleArticle12-15SummaryOfInvestments-OtherThanInvestmentsInRelatedPartiesSummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesTable |
 | us-gaap:FixedIncomeInvestmentsMember | parent-child | http://fasb.org/us-gaap/role/disclosure/FinancialServicesInvestmentCompany |
 | us-gaap:FixedIncomeInvestmentsMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialServicesInvestmentCompanyInvestmentHoldingsTable |