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 | us-gaap:OtherThanSecuritiesInvestmentMember | domain-member | http://fasb.org/us-gaap/role/disclosure/InvestmentHoldings |
 | us-gaap:OtherThanSecuritiesInvestmentMember | parent-child | http://fasb.org/us-gaap/role/disclosure/SummaryOfInvestmentHoldings |
 | us-gaap:OtherThanSecuritiesInvestmentMember | domain-member | http://fasb.org/us-gaap/role/disclosure/SummaryOfInvestmentHoldings |
 | us-gaap:OtherThanSecuritiesInvestmentMember | parent-child | http://fasb.org/us-gaap/role/disclosure/OtherThanSecuritiesInvestmentHoldings |
 | us-gaap:OtherThanSecuritiesInvestmentMember | domain-member | http://fasb.org/us-gaap/role/disclosure/OtherThanSecuritiesInvestmentHoldingsInvestmentHoldingsOtherThanSecuritiesTable |
 | us-gaap:OtherThanSecuritiesInvestmentMember | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentsFederalTaxNote |
 | us-gaap:OtherThanSecuritiesInvestmentMember | domain-member | http://fasb.org/us-gaap/role/disclosure/InvestmentsFederalTaxNoteFederalIncomeTaxNoteTable |
 | us-gaap:MutualFundMember | parent-child | http://fasb.org/us-gaap/role/disclosure/CompensationRelatedCostsRetirementBenefits |
 | us-gaap:MutualFundMember | domain-member | http://fasb.org/us-gaap/role/disclosure/CompensationRelatedCostsRetirementBenefitsDefinedBenefitPlanPlanAssetsAllocationTable |
 | us-gaap:MutualFundMember | domain-member | http://fasb.org/us-gaap/role/disclosure/CompensationRelatedCostsRetirementBenefitsDefinedBenefitPlanPlanAssetsCategoryTable |
 | us-gaap:MutualFundMember | domain-member | http://fasb.org/us-gaap/role/disclosure/CompensationRelatedCostsRetirementBenefitsDefinedBenefitPlanPlanAssetsLevel3ReconciliationTable |
 | us-gaap:MutualFundMember | domain-member | http://fasb.org/us-gaap/role/disclosure/CompensationRelatedCostsRetirementBenefitsScheduleOfDefinedBenefitPlansDisclosuresTable |
 | us-gaap:MutualFundMember | parent-child | http://fasb.org/us-gaap/role/disclosure/FinancialServicesInsurance |
 | us-gaap:MutualFundMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialServicesInsuranceScheduleOfFairValueOfSeparateAccountsByMajorCategoryOfInvestmentTable |
 | us-gaap:MutualFundMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialServicesInsuranceScheduleOfInvestmentIncomeReportedAmountsByCategoryTable |
 | us-gaap:OtherThanSecuritiesInvestmentMember | parent-child | http://fasb.org/us-gaap/role/disclosure/FinancialServicesInvestmentCompany |
 | us-gaap:OtherThanSecuritiesInvestmentMember | domain-member | http://fasb.org/us-gaap/role/disclosure/FinancialServicesInvestmentCompanyInvestmentHoldingsTable |