http://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://principal.com/20211231#OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortizationhttp://fasb.org/us-gaap/2021-01-31#PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortizationhttp://fasb.org/us-gaap/2021-01-31#PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortizationhttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitieshttp://fasb.org/us-gaap/2021-01-31#OtherLiabilities0001126328--12-312021FYfalse0.0605http://fasb.org/us-gaap/2021-01-31#PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortizationhttp://fasb.org/us-gaap/2021-01-31#PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortizationhttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitieshttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitieshttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMemberhttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMemberhttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMemberhttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMemberhttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMemberhttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMemberhttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMemberhttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMemberhttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMemberhttp://fasb.org/us-gaap/2021-01-31#ValuationTechniqueDiscountedCashFlowMember0001126328us-gaap:TreasuryStockMember2021-01-012021-12-310001126328us-gaap:TreasuryStockMember2020-01-012020-12-310001126328us-gaap:TreasuryStockMember2019-01-012019-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:USTreasuryAndGovernmentMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:USStatesAndPoliticalSubdivisionsMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:RedeemablePreferredStockMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:PublicUtilityBondsMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:OtherDebtSecuritiesMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:ForeignGovernmentDebtSecuritiesMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:DebtSecuritiesMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:CommercialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:CollateralizedDebtObligationsMember2021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:AllOtherCorporateBondsMember2021-12-310001126328pfg:TradingSecuritiesMemberus-gaap:DebtSecuritiesMember2021-12-310001126328us-gaap:RealEstateInvestmentMember2021-12-310001126328us-gaap:RealEstateAcquiredInSatisfactionOfDebtMember2021-12-310001126328us-gaap:PublicUtilityEquitiesMember2021-12-310001126328us-gaap:PolicyLoansMember2021-12-310001126328us-gaap:OtherLongTermInvestmentsMember2021-12-310001126328us-gaap:NonredeemablePreferredStockMember2021-12-310001126328us-gaap:IndustrialMiscellaneousAndAllOthersMember2021-12-310001126328us-gaap:EquitySecuritiesMember2021-12-310001126328us-gaap:BanksTrustAndInsuranceEquitiesMember2021-12-310001126328pfg:OtherCorporateEquitiesMember2021-12-310001126328pfg:MortgageLoansMember2021-12-310001126328us-gaap:TreasuryStockMember2021-12-310001126328us-gaap:RetainedEarningsMember2021-12-310001126328us-gaap:NoncontrollingInterestMember2021-12-310001126328us-gaap:AdditionalPaidInCapitalMember2021-12-310001126328us-gaap:TreasuryStockMember2020-12-310001126328us-gaap:RetainedEarningsMember2020-12-310001126328us-gaap:NoncontrollingInterestMember2020-12-310001126328us-gaap:AdditionalPaidInCapitalMember2020-12-310001126328srt:CumulativeEffectPeriodOfAdoptionAdjustmentMemberus-gaap:AccountingStandardsUpdate201613Memberus-gaap:RetainedEarningsMember2019-12-310001126328srt:CumulativeEffectPeriodOfAdoptionAdjustmentMemberus-gaap:AccountingStandardsUpdate201613Member2019-12-310001126328us-gaap:TreasuryStockMember2019-12-310001126328us-gaap:RetainedEarningsMember2019-12-310001126328us-gaap:NoncontrollingInterestMember2019-12-310001126328us-gaap:AdditionalPaidInCapitalMember2019-12-310001126328srt:CumulativeEffectPeriodOfAdoptionAdjustmentMemberus-gaap:AccountingStandardsUpdate201602Memberus-gaap:RetainedEarningsMember2018-12-310001126328srt:CumulativeEffectPeriodOfAdoptionAdjustmentMemberus-gaap:AccountingStandardsUpdate201602Member2018-12-310001126328us-gaap:TreasuryStockMember2018-12-310001126328us-gaap:RetainedEarningsMember2018-12-310001126328us-gaap:NoncontrollingInterestMember2018-12-310001126328us-gaap:AdditionalPaidInCapitalMember2018-12-310001126328us-gaap:AccumulatedTranslationAdjustmentMember2021-12-310001126328us-gaap:AccumulatedOtherComprehensiveIncomeMember2021-12-310001126328us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2021-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2021-12-310001126328srt:CumulativeEffectPeriodOfAdoptionAdjustmentMemberus-gaap:AccountingStandardsUpdate201613Memberus-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember2020-12-310001126328srt:CumulativeEffectPeriodOfAdoptionAdjustmentMemberus-gaap:AccountingStandardsUpdate201613Memberpfg:AccumulatedNoncreditOtherThanTemporaryImpairmentMember2020-12-310001126328us-gaap:AccumulatedTranslationAdjustmentMember2020-12-310001126328us-gaap:AccumulatedOtherComprehensiveIncomeMember2020-12-310001126328us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2020-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2020-12-310001126328us-gaap:AccumulatedTranslationAdjustmentMember2019-12-310001126328us-gaap:AccumulatedOtherComprehensiveIncomeMember2019-12-310001126328us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember2019-12-310001126328us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2019-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2019-12-310001126328pfg:AccumulatedNoncreditOtherThanTemporaryImpairmentMember2019-12-310001126328us-gaap:AccumulatedTranslationAdjustmentMember2018-12-310001126328us-gaap:AccumulatedOtherComprehensiveIncomeMember2018-12-310001126328us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember2018-12-310001126328us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2018-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2018-12-310001126328pfg:AccumulatedNoncreditOtherThanTemporaryImpairmentMember2018-12-310001126328pfg:SubsidiariesPrincipalLifeInsuranceCompanyMember2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMember2020-01-012020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMember2019-01-012019-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractsAccidentYear2018Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractsAccidentYear2017Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2016Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2015Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2014Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2013Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractAccidentYear2021Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractAccidentYear2020Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractAccidentYear2019Member2021-12-310001126328pfg:GroupLifeMemberus-gaap:ShortDurationInsuranceContractAccidentYear2021Member2021-12-310001126328pfg:GroupLifeMemberus-gaap:ShortDurationInsuranceContractAccidentYear2020Member2021-12-310001126328pfg:DentalVisionShortTermDisabilityCriticalIllnessAccidentMemberus-gaap:ShortDurationInsuranceContractAccidentYear2021Member2021-12-310001126328pfg:DentalVisionShortTermDisabilityCriticalIllnessAccidentMemberus-gaap:ShortDurationInsuranceContractAccidentYear2020Member2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractsAccidentYear2018Member2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractsAccidentYear2017Member2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2016Member2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2015Member2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2014Member2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2013Member2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractAccidentYear2020Member2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractAccidentYear2019Member2020-12-310001126328pfg:GroupLifeMemberus-gaap:ShortDurationInsuranceContractAccidentYear2020Member2020-12-310001126328pfg:DentalVisionShortTermDisabilityCriticalIllnessAccidentMemberus-gaap:ShortDurationInsuranceContractAccidentYear2020Member2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractsAccidentYear2018Member2019-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractsAccidentYear2017Member2019-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2016Member2019-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2015Member2019-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2014Member2019-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2013Member2019-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2019-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractAccidentYear2019Member2019-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractsAccidentYear2018Member2018-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractsAccidentYear2017Member2018-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2016Member2018-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2015Member2018-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2014Member2018-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2013Member2018-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2018-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortDurationInsuranceContractsAccidentYear2017Member2017-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2016Member2017-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2015Member2017-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2014Member2017-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2013Member2017-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2017-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2016Member2016-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2015Member2016-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2014Member2016-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2013Member2016-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2016-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2015Member2015-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2014Member2015-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2015-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2014Member2014-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2013Member2014-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2014-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2013Member2013-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2013-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMemberus-gaap:ShortdurationInsuranceContractsAccidentYear2012Member2012-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMember2021-01-012021-12-310001126328pfg:GroupLifeMember2021-01-012021-12-310001126328pfg:DentalVisionShortTermDisabilityCriticalIllnessAccidentMember2021-01-012021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMembersrt:MinimumMember2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMembersrt:MaximumMember2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMembersrt:MinimumMember2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMembersrt:MaximumMember2020-12-310001126328pfg:GroupLifeMember2021-12-310001126328pfg:DentalVisionShortTermDisabilityCriticalIllnessAccidentMember2021-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMember2020-12-310001126328pfg:GroupLifeMember2020-12-310001126328pfg:DentalVisionShortTermDisabilityCriticalIllnessAccidentMember2020-12-310001126328us-gaap:CommonStockMember2021-12-310001126328us-gaap:CommonStockMember2019-12-310001126328us-gaap:CommonStockMember2018-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceTotalRangeMember2021-01-012021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange5Member2021-01-012021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange4Member2021-01-012021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange3Member2021-01-012021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange2Member2021-01-012021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange1Member2021-01-012021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceTotalRangeMember2021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange5Member2021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange4Member2021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange3Member2021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange2Member2021-12-310001126328us-gaap:EmployeeStockOptionMemberpfg:ExercisePriceRange1Member2021-12-310001126328us-gaap:EmployeeStockOptionMember2020-12-310001126328pfg:StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember2020-01-012020-12-310001126328pfg:StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember2019-01-012019-12-310001126328pfg:StockBasedCompensationPlans2021StockIncentivePlanMember2021-12-310001126328us-gaap:RestrictedStockUnitsRSUMember2020-12-310001126328us-gaap:PerformanceSharesMember2020-12-310001126328us-gaap:RestrictedStockUnitsRSUMemberpfg:StockBasedCompensationPlans2021StockIncentivePlan2020DirectorsStockPlan2014DirectorsStockPlanAnd2005DirectorsStockPlanMember2021-01-012021-12-310001126328us-gaap:RestrictedStockUnitsRSUMemberpfg:StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember2021-01-012021-12-310001126328pfg:StockBasedCompensationPlans2014StockIncentivePlanAmendedAndRestated2010StockIncentivePlanStockIncentivePlanMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:DepositAccountMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsSpreadMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:AdministrativeServiceMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentSpecialtyBenefitsInsuranceMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:AdministrativeServiceMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentIndividualLifeInsuranceMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:AdministrativeServiceMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CommissionIncomeMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentIndividualLifeInsuranceMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CommissionIncomeMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsSpreadMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:ManagementServiceMemberpfg:SegmentPrincipalInternationalMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:ManagementServiceMemberpfg:SegmentPrincipalGlobalInvestorsMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentPrincipalInternationalMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentPrincipalGlobalInvestorsMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentCorporateMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMembersrt:LatinAmericaMemberpfg:SegmentPrincipalInternationalMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMembersrt:AsiaMemberpfg:SegmentPrincipalInternationalMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentUSInsuranceSolutionsEliminationsMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentGeographicalAreaEliminationsMemberpfg:SegmentPrincipalInternationalMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:ProductsAndServicesEliminationsMemberpfg:SegmentCorporateMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CorporateAndRegionalMemberpfg:SegmentPrincipalInternationalMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CommissionIncomeMemberpfg:SegmentCorporateMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:DepositAccountMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsSpreadMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:AdministrativeServiceMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentSpecialtyBenefitsInsuranceMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:AdministrativeServiceMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentIndividualLifeInsuranceMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:AdministrativeServiceMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CommissionIncomeMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentIndividualLifeInsuranceMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CommissionIncomeMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsSpreadMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:ManagementServiceMemberpfg:SegmentPrincipalInternationalMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:ManagementServiceMemberpfg:SegmentPrincipalGlobalInvestorsMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentPrincipalInternationalMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentPrincipalGlobalInvestorsMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentCorporateMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMembersrt:LatinAmericaMemberpfg:SegmentPrincipalInternationalMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMembersrt:AsiaMemberpfg:SegmentPrincipalInternationalMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentUSInsuranceSolutionsEliminationsMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentGeographicalAreaEliminationsMemberpfg:SegmentPrincipalInternationalMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:ProductsAndServicesEliminationsMemberpfg:SegmentCorporateMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CorporateAndRegionalMemberpfg:SegmentPrincipalInternationalMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CommissionIncomeMemberpfg:SegmentCorporateMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:DepositAccountMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsSpreadMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:AdministrativeServiceMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentSpecialtyBenefitsInsuranceMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:AdministrativeServiceMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentIndividualLifeInsuranceMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:AdministrativeServiceMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CommissionIncomeMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentIndividualLifeInsuranceMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:ManagementServiceMemberpfg:SegmentPrincipalInternationalMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:ManagementServiceMemberpfg:SegmentPrincipalGlobalInvestorsMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentPrincipalInternationalMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentPrincipalGlobalInvestorsMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberus-gaap:FinancialServiceOtherMemberpfg:SegmentCorporateMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMembersrt:LatinAmericaMemberpfg:SegmentPrincipalInternationalMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMembersrt:AsiaMemberpfg:SegmentPrincipalInternationalMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentUSInsuranceSolutionsEliminationsMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentGeographicalAreaEliminationsMemberpfg:SegmentPrincipalInternationalMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:ProductsAndServicesEliminationsMemberpfg:SegmentCorporateMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CorporateAndRegionalMemberpfg:SegmentPrincipalInternationalMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:CommissionIncomeMemberpfg:SegmentCorporateMember2019-01-012019-12-310001126328pfg:NotesPayable6.05PercentDue2036Memberus-gaap:SeniorNotesMember2016-10-012016-12-310001126328pfg:NotesPayable7.875PercentDue2014Memberus-gaap:SeniorNotesMember2012-09-052012-09-050001126328pfg:SuttonCaymanLtd.Memberpfg:ReinsuranceMemberus-gaap:SubsequentEventMemberpfg:MasterTransactionAgreementMember2022-01-312022-01-310001126328pfg:SuttonCaymanLtd.Memberpfg:CoinsuranceWithFundsWithheldMemberus-gaap:SubsequentEventMemberpfg:MasterTransactionAgreementMember2022-01-312022-01-310001126328pfg:OperatingExpensesMemberus-gaap:AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2021-01-012021-12-310001126328pfg:NetRealizedCapitalGainsLossesMemberus-gaap:AccumulatedNetInvestmentGainLossIncludingPortionAttributableToNoncontrollingInterestMember2021-01-012021-12-310001126328pfg:NetRealizedCapitalGainsLossesMemberus-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2021-01-012021-12-310001126328pfg:OperatingExpensesMemberus-gaap:AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2020-01-012020-12-310001126328pfg:NetRealizedCapitalGainsLossesMemberus-gaap:AccumulatedNetInvestmentGainLossIncludingPortionAttributableToNoncontrollingInterestMember2020-01-012020-12-310001126328pfg:NetRealizedCapitalGainsLossesMemberus-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2020-01-012020-12-310001126328pfg:NetIncomeLossAttributableToNoncontrollingInterestMemberus-gaap:AccumulatedForeignCurrencyAdjustmentAttributableToNoncontrollingInterestMember2020-01-012020-12-310001126328pfg:OperatingExpensesMemberus-gaap:AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2019-01-012019-12-310001126328pfg:NetRealizedCapitalGainsLossesMemberus-gaap:AccumulatedNetInvestmentGainLossIncludingPortionAttributableToNoncontrollingInterestMember2019-01-012019-12-310001126328pfg:NetRealizedCapitalGainsLossesMemberus-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2019-01-012019-12-310001126328pfg:NetIncomeLossAttributableToNoncontrollingInterestMemberus-gaap:AccumulatedForeignCurrencyAdjustmentAttributableToNoncontrollingInterestMember2019-01-012019-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMember2020-01-022020-12-310001126328pfg:ReinsuranceRecoverablesMember2020-01-022020-12-310001126328pfg:SubsegmentIndividualLifeInsuranceMember2021-01-012021-12-310001126328pfg:SubsegmentIndividualLifeInsuranceMember2020-01-012020-12-310001126328pfg:SubsegmentIndividualLifeInsuranceMember2019-01-012019-12-310001126328pfg:AccumulatedNoncreditOtherThanTemporaryImpairmentMember2019-01-012019-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:NetInvestmentHedgingMember2021-01-012021-12-310001126328us-gaap:NetInvestmentHedgingMember2021-01-012021-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:NetInvestmentHedgingMember2020-01-012020-12-310001126328us-gaap:NetInvestmentHedgingMember2020-01-012020-12-310001126328pfg:InvestmentContractMemberus-gaap:InterestRateContractMember2021-01-012021-12-310001126328pfg:FixedMaturitiesSecuritiesAvailableForSaleMemberus-gaap:ForeignExchangeContractMember2021-01-012021-12-310001126328pfg:FixedMaturitiesSecuritiesAvailableForSaleMemberus-gaap:InterestRateContractMember2020-01-012020-12-310001126328pfg:FixedMaturitiesSecuritiesAvailableForSaleMemberus-gaap:ForeignExchangeContractMember2020-01-012020-12-310001126328pfg:FixedMaturitiesSecuritiesAvailableForSaleMemberus-gaap:InterestRateContractMember2019-01-012019-12-310001126328pfg:FixedMaturitiesSecuritiesAvailableForSaleMemberus-gaap:ForeignExchangeContractMember2019-01-012019-12-310001126328us-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2021-01-012021-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2021-01-012021-12-310001126328us-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2020-01-012020-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2020-01-012020-12-310001126328us-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2019-01-012019-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember2019-01-012019-12-310001126328us-gaap:AccumulatedTranslationAdjustmentMember2021-01-012021-12-310001126328us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember2021-01-012021-12-310001126328us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2021-01-012021-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2021-01-012021-12-310001126328us-gaap:AccumulatedTranslationAdjustmentMember2020-01-012020-12-310001126328us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember2020-01-012020-12-310001126328us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2020-01-012020-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2020-01-012020-12-310001126328us-gaap:AccumulatedTranslationAdjustmentMember2019-01-012019-12-310001126328us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember2019-01-012019-12-310001126328us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2019-01-012019-12-310001126328us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2019-01-012019-12-310001126328us-gaap:InterestRateContractMemberus-gaap:CashFlowHedgingMemberus-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember2021-01-012021-12-310001126328pfg:LawsuitAllegingBreachOfFiduciaryDutyInConnectionWithPrincipalFixedIncomeOptionMember2021-12-310001126328pfg:PrincipalInternationalChileMemberpfg:UnsecuredLineOfCreditMember2021-12-310001126328pfg:PrincipalFinancialServicesIncAndPrincipalLifeInsuranceCompanyAndPrincipalFinancialServicesVLTDAndPrincipalFinancialGroupCoborrowersMemberpfg:CreditFacilityMaturingNovember2023Member2021-12-310001126328pfg:PrincipalFinancialServicesIncAndPrincipalLifeInsuranceCompanyAndPrincipalFinancialGroupCoborrowersMemberpfg:CreditFacilityMaturingNovember2023Member2021-12-310001126328pfg:PrincipalInternationalChileMemberpfg:UnsecuredLineOfCreditMember2020-12-310001126328pfg:PrincipalFinancialServicesIncAndPrincipalLifeInsuranceCompanyAndPrincipalFinancialServicesVLTDAndPrincipalFinancialGroupCoborrowersMemberpfg:CreditFacilityMaturingNovember2023Member2020-12-310001126328pfg:PrincipalFinancialServicesIncAndPrincipalLifeInsuranceCompanyAndPrincipalFinancialGroupCoborrowersMemberpfg:CreditFacilityMaturingNovember2023Member2020-12-310001126328pfg:WMAdvisorsMember2021-12-310001126328pfg:WMAdvisorsMember2020-12-310001126328pfg:GuaranteesToUnconsolidatedTrustsUnderContingentFundingAgreementsMember2021-12-310001126328pfg:GuaranteesToThirdPartiesPrimarilyRelatedToFormerSubsidiariesAndJointVenturesMember2021-12-310001126328pfg:SegmentUSInsuranceSolutionsMember2019-12-310001126328pfg:SegmentRetirementAndIncomeSolutionsMember2019-12-310001126328pfg:SegmentPrincipalInternationalMember2019-12-310001126328pfg:SegmentPrincipalGlobalInvestorsMember2019-12-310001126328pfg:SegmentCorporateMember2019-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:CashFlowHedgingMemberus-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember2021-01-012021-12-310001126328us-gaap:InterestRateContractMemberus-gaap:CashFlowHedgingMemberus-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember2020-01-012020-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:NetInvestmentHedgingMemberus-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember2020-01-012020-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:CashFlowHedgingMemberus-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember2020-01-012020-12-310001126328us-gaap:NetInvestmentHedgingMemberus-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember2020-01-012020-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:CashFlowHedgingMemberus-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember2019-01-012019-12-310001126328us-gaap:InterestRateContractMemberus-gaap:CashFlowHedgingMemberpfg:NetRealizedCapitalGainsLossesMember2021-01-012021-12-310001126328us-gaap:InterestRateContractMemberus-gaap:CashFlowHedgingMemberpfg:NetRealizedCapitalGainsLossesMember2020-01-012020-12-310001126328us-gaap:InterestRateContractMemberus-gaap:CashFlowHedgingMemberpfg:NetRealizedCapitalGainsLossesMember2019-01-012019-12-310001126328us-gaap:CashFlowHedgingMemberpfg:NetRealizedCapitalGainsLossesMember2021-01-012021-12-310001126328us-gaap:CashFlowHedgingMemberpfg:NetInvestmentIncomeLossMember2021-01-012021-12-310001126328us-gaap:CashFlowHedgingMemberpfg:BenefitsClaimsAndSettlementExpensesMember2021-01-012021-12-310001126328us-gaap:CashFlowHedgingMemberpfg:NetRealizedCapitalGainsLossesMember2020-01-012020-12-310001126328us-gaap:CashFlowHedgingMemberpfg:NetInvestmentIncomeLossMember2020-01-012020-12-310001126328us-gaap:CashFlowHedgingMemberpfg:BenefitsClaimsAndSettlementExpensesMember2020-01-012020-12-310001126328us-gaap:CashFlowHedgingMemberpfg:OperatingExpensesMember2019-01-012019-12-310001126328us-gaap:CashFlowHedgingMemberpfg:NetRealizedCapitalGainsLossesMember2019-01-012019-12-310001126328us-gaap:CashFlowHedgingMemberpfg:NetInvestmentIncomeLossMember2019-01-012019-12-310001126328us-gaap:CashFlowHedgingMemberpfg:BenefitsClaimsAndSettlementExpensesMember2019-01-012019-12-310001126328us-gaap:ResidentialMortgageMember2020-01-012020-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMember2020-01-012020-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMember2019-01-012019-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember2021-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancingReceivables60To89DaysPastDueMember2021-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancingReceivables30To59DaysPastDueMember2021-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancialAssetPastDueMember2021-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancialAssetNotPastDueMember2021-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMemberus-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember2021-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMemberus-gaap:FinancingReceivables60To89DaysPastDueMember2021-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMemberus-gaap:FinancialAssetPastDueMember2021-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMemberus-gaap:FinancialAssetNotPastDueMember2021-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMemberus-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember2021-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMemberus-gaap:FinancingReceivables30To59DaysPastDueMember2021-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMemberus-gaap:FinancialAssetPastDueMember2021-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMemberus-gaap:FinancialAssetNotPastDueMember2021-12-310001126328pfg:StandardPoorsBPlusAndBelowRatingMemberus-gaap:FinanceLeasesPortfolioSegmentMember2021-12-310001126328pfg:StandardPoorsBPlusAndBelowRatingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:StandardPoorsBBPlusThruBBMinusRatingMemberus-gaap:FinanceLeasesPortfolioSegmentMember2021-12-310001126328pfg:StandardPoorsBBPlusThruBBMinusRatingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:StandardPoorsBBBPlusThruBBBMinusRatingMemberus-gaap:FinanceLeasesPortfolioSegmentMember2021-12-310001126328pfg:StandardPoorsBBBPlusThruBBBMinusRatingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:StandardPoorsAMinusAndAboveRatingMemberus-gaap:FinanceLeasesPortfolioSegmentMember2021-12-310001126328pfg:StandardPoorsAMinusAndAboveRatingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:PerformingMemberus-gaap:ResidentialMortgageMember2021-12-310001126328pfg:NonperformingMemberus-gaap:ResidentialMortgageMember2021-12-310001126328us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember2021-12-310001126328us-gaap:FinancingReceivables60To89DaysPastDueMember2021-12-310001126328us-gaap:FinancingReceivables30To59DaysPastDueMember2021-12-310001126328us-gaap:FinancialAssetPastDueMember2021-12-310001126328us-gaap:FinancialAssetNotPastDueMember2021-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember2020-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancingReceivables60To89DaysPastDueMember2020-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancingReceivables30To59DaysPastDueMember2020-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancialAssetPastDueMember2020-12-310001126328us-gaap:ResidentialMortgageMemberus-gaap:FinancialAssetNotPastDueMember2020-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMemberus-gaap:FinancingReceivables60To89DaysPastDueMember2020-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMemberus-gaap:FinancialAssetPastDueMember2020-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMemberus-gaap:FinancialAssetNotPastDueMember2020-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMemberus-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember2020-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMemberus-gaap:FinancingReceivables60To89DaysPastDueMember2020-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMemberus-gaap:FinancingReceivables30To59DaysPastDueMember2020-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMemberus-gaap:FinancialAssetPastDueMember2020-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMemberus-gaap:FinancialAssetNotPastDueMember2020-12-310001126328pfg:StandardPoorsBBPlusThruBBMinusRatingMemberus-gaap:FinanceLeasesPortfolioSegmentMember2020-12-310001126328us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember2020-12-310001126328us-gaap:FinancingReceivables60To89DaysPastDueMember2020-12-310001126328us-gaap:FinancingReceivables30To59DaysPastDueMember2020-12-310001126328us-gaap:FinancialAssetPastDueMember2020-12-310001126328us-gaap:FinancialAssetNotPastDueMember2020-12-310001126328us-gaap:ResidentialMortgageMember2021-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMember2021-12-310001126328pfg:ReinsuranceRecoverablesMember2021-12-310001126328pfg:ReinsuranceRecoverablesMember2020-12-310001126328us-gaap:ResidentialMortgageMember2020-01-010001126328us-gaap:CommercialRealEstatePortfolioSegmentMember2020-01-010001126328pfg:ReinsuranceRecoverablesMember2020-01-0100011263282020-01-010001126328us-gaap:ResidentialMortgageMember2018-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMember2018-12-310001126328us-gaap:ResidentialMortgageMember2019-01-012019-12-310001126328us-gaap:ResidentialMortgageMember2019-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMember2019-12-310001126328us-gaap:EquityMethodInvestmentsMember2021-01-012021-12-310001126328us-gaap:EquityMethodInvestmentsMember2020-01-012020-12-310001126328us-gaap:EquityMethodInvestmentsMember2019-01-012019-12-310001126328pfg:CommercialMortgageLoansOfConsolidatedVariableInterestEntitiesMember2019-01-012019-12-310001126328us-gaap:FairValueMeasurementsRecurringMember2019-12-310001126328us-gaap:FairValueMeasurementsRecurringMember2018-12-310001126328pfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328pfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328pfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMember2019-12-310001126328pfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMember2018-12-310001126328us-gaap:USStatesAndPoliticalSubdivisionsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:TradingSecuritiesMember2021-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:TradingSecuritiesMember2019-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueMeasurementsRecurringMember2019-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueMeasurementsRecurringMember2019-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2018-12-310001126328us-gaap:ForeignGovernmentDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2018-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2018-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2018-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2018-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2018-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueMeasurementsRecurringMember2018-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueMeasurementsRecurringMember2018-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:TradingSecuritiesMember2020-01-012020-12-310001126328us-gaap:ForeignGovernmentDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-01-012019-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:TradingSecuritiesMember2021-01-012021-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:TradingSecuritiesMember2019-01-012019-12-310001126328us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember2021-12-310001126328us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember2020-12-310001126328us-gaap:EmployeeStockOptionMember2020-01-012020-12-310001126328us-gaap:EmployeeStockOptionMember2019-01-012019-12-310001126328us-gaap:EmployeeStockOptionMember2021-01-012021-12-310001126328us-gaap:RestrictedStockUnitsRSUMember2021-12-310001126328us-gaap:PerformanceSharesMember2021-12-310001126328us-gaap:EmployeeStockOptionMember2021-12-310001126328us-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328us-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputPriceVolatilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLapseRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputNonPerformanceRiskMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLongDurationInterestRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputPriceVolatilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLapseRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputNonPerformanceRiskMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLongDurationInterestRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputPriceVolatilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLapseRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputNonPerformanceRiskMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLongDurationInterestRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputPriceVolatilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLapseRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputNonPerformanceRiskMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputPriceVolatilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLapseRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputNonPerformanceRiskMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MinimumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLongDurationInterestRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputPriceVolatilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLapseRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputNonPerformanceRiskMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MaximumMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLongDurationInterestRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328pfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsSpreadMember2021-01-012021-12-310001126328pfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2021-01-012021-12-310001126328us-gaap:SingleStockFutureMember2021-12-310001126328us-gaap:EmbeddedDerivativeFinancialInstrumentsMember2021-12-310001126328pfg:InterestRateFutureMember2021-12-310001126328us-gaap:SwaptionMember2020-12-310001126328us-gaap:SingleStockFutureMember2020-12-310001126328us-gaap:EmbeddedDerivativeFinancialInstrumentsMember2020-12-310001126328pfg:InterestRateFutureMember2020-12-310001126328us-gaap:OtherContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2021-12-310001126328us-gaap:OtherContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2020-12-310001126328us-gaap:InterestRateContractMemberus-gaap:DesignatedAsHedgingInstrumentMember2020-12-310001126328us-gaap:OtherContractMember2021-01-012021-12-310001126328us-gaap:InterestRateContractMember2021-01-012021-12-310001126328us-gaap:ForeignExchangeContractMember2021-01-012021-12-310001126328us-gaap:EquityContractMember2021-01-012021-12-310001126328us-gaap:CreditRiskContractMember2021-01-012021-12-310001126328us-gaap:OtherContractMember2020-01-012020-12-310001126328us-gaap:InterestRateContractMember2020-01-012020-12-310001126328us-gaap:ForeignExchangeContractMember2020-01-012020-12-310001126328us-gaap:EquityContractMember2020-01-012020-12-310001126328us-gaap:CreditRiskContractMember2020-01-012020-12-310001126328us-gaap:OtherContractMember2019-01-012019-12-310001126328us-gaap:InterestRateContractMember2019-01-012019-12-310001126328us-gaap:ForeignExchangeContractMember2019-01-012019-12-310001126328us-gaap:EquityContractMember2019-01-012019-12-310001126328us-gaap:CreditRiskContractMember2019-01-012019-12-310001126328us-gaap:InterestRateContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2021-12-310001126328us-gaap:InterestRateContractMemberus-gaap:DesignatedAsHedgingInstrumentMember2021-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2021-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:DesignatedAsHedgingInstrumentMember2021-12-310001126328us-gaap:EquityContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2021-12-310001126328us-gaap:CreditRiskContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2021-12-310001126328us-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2021-12-310001126328us-gaap:DesignatedAsHedgingInstrumentMember2021-12-310001126328us-gaap:InterestRateContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2020-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2020-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:DesignatedAsHedgingInstrumentMember2020-12-310001126328us-gaap:EquityContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2020-12-310001126328us-gaap:CreditRiskContractMemberus-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2020-12-310001126328us-gaap:NotDesignatedAsHedgingInstrumentEconomicHedgeMember2020-12-310001126328us-gaap:DesignatedAsHedgingInstrumentMember2020-12-310001126328pfg:SegmentCorporateMember2021-01-012021-12-310001126328pfg:SegmentCorporateMember2020-01-012020-12-310001126328pfg:SegmentCorporateMember2019-01-012019-12-310001126328us-gaap:QualifiedPlanMemberpfg:DefinedContributionPlanGeneralParticipantMember2021-01-012021-12-310001126328us-gaap:NonqualifiedPlanMemberpfg:DefinedContributionPlanGrandfatheredChoiceParticipantMember2021-01-012021-12-310001126328us-gaap:NonqualifiedPlanMemberpfg:DefinedContributionPlanGeneralParticipantMember2021-01-012021-12-310001126328srt:MinimumMemberus-gaap:FixedIncomeSecuritiesMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328srt:MinimumMemberus-gaap:DefinedBenefitPlanEquitySecuritiesMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328srt:MinimumMemberpfg:AlternativesMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328srt:MaximumMemberus-gaap:FixedIncomeSecuritiesMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328srt:MaximumMemberus-gaap:DefinedBenefitPlanEquitySecuritiesMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328srt:MaximumMemberpfg:AlternativesMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanRealEstateMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:USTreasuryAndGovernmentMemberus-gaap:FairValueInputsLevel1Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:USStatesAndPoliticalSubdivisionsMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:HedgeFundsMemberus-gaap:FairValueMeasuredAtNetAssetValuePerShareMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanRealEstateMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesUsLargeCapMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesNonUsMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328pfg:SingleClientSeparateAccountsInvestedInPooledSeparateAccountMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328pfg:OtherPlanAssetsMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328pfg:DefinedBenefitPlanEquitySecuritiesUsSmallMidCapMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328pfg:BalancedAssetAllocationPortfoliosMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:USTreasuryAndGovernmentMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:USStatesAndPoliticalSubdivisionsMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:OtherDebtSecuritiesMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:HedgeFundsMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanRealEstateMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesUsLargeCapMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesNonUsMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:CorporateDebtSecuritiesMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328pfg:SingleClientSeparateAccountsInvestedInPooledSeparateAccountMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328pfg:OtherPlanAssetsMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328pfg:DefinedBenefitPlanEquitySecuritiesUsSmallMidCapMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328pfg:BalancedAssetAllocationPortfoliosMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:FixedIncomeSecuritiesMemberus-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:FairValueMeasuredAtNetAssetValuePerShareMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesUsMemberus-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesNonUsMemberus-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanCashAndCashEquivalentsMemberus-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesUsMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesNonUsMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:DefinedBenefitPlanCashAndCashEquivalentsMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:USTreasuryAndGovernmentMemberus-gaap:FairValueInputsLevel1Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:USStatesAndPoliticalSubdivisionsMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:HedgeFundsMemberus-gaap:FairValueMeasuredAtNetAssetValuePerShareMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanRealEstateMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesUsLargeCapMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesNonUsMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328pfg:SingleClientSeparateAccountsInvestedInPooledSeparateAccountMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328pfg:OtherPlanAssetsMemberus-gaap:FairValueInputsLevel2Memberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328pfg:DefinedBenefitPlanEquitySecuritiesUsSmallMidCapMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328pfg:BalancedAssetAllocationPortfoliosMemberus-gaap:FairValueInputsLevel2Memberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:USTreasuryAndGovernmentMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:USStatesAndPoliticalSubdivisionsMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:OtherDebtSecuritiesMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:HedgeFundsMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanRealEstateMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesUsLargeCapMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesNonUsMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:CorporateDebtSecuritiesMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328pfg:SingleClientSeparateAccountsInvestedInPooledSeparateAccountMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328pfg:OtherPlanAssetsMemberpfg:SingleClientSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328pfg:DefinedBenefitPlanEquitySecuritiesUsSmallMidCapMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328pfg:BalancedAssetAllocationPortfoliosMemberpfg:PooledSeparateAccountInvestmentsMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:FixedIncomeSecuritiesMemberus-gaap:FairValueInputsLevel2Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:FixedIncomeSecuritiesMemberus-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:FairValueMeasuredAtNetAssetValuePerShareMemberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesUsMemberus-gaap:FairValueInputsLevel2Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesUsMemberus-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesNonUsMemberus-gaap:FairValueInputsLevel2Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesNonUsMemberus-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanCashAndCashEquivalentsMemberus-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:FixedIncomeSecuritiesMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesUsMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanEquitySecuritiesNonUsMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:DefinedBenefitPlanCashAndCashEquivalentsMemberus-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328srt:MaximumMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:PensionPlansDefinedBenefitMember2019-12-310001126328us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2019-12-310001126328pfg:PensionPlansDefinedBenefitTraditionalBenefitMember2021-01-012021-12-310001126328pfg:PensionPlansDefinedBenefitCashBalanceBenefitMember2021-01-012021-12-310001126328pfg:PensionPlansDefinedBenefitTraditionalBenefitMember2020-01-012020-12-310001126328pfg:PensionPlansDefinedBenefitCashBalanceBenefitMember2020-01-012020-12-310001126328pfg:PensionPlansDefinedBenefitTraditionalBenefitMember2019-01-012019-12-310001126328pfg:PensionPlansDefinedBenefitCashBalanceBenefitMember2019-01-012019-12-310001126328pfg:Post65MedicalPlansMember2021-01-012021-12-310001126328pfg:HomeOfficeMedicalAndLifePlansMember2021-01-012021-12-310001126328pfg:AgentMedicalAndLifePlanMember2021-01-012021-12-310001126328us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-04-012020-12-310001126328us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-01-012020-03-310001126328us-gaap:PensionPlansDefinedBenefitMember2019-06-012019-12-310001126328us-gaap:PensionPlansDefinedBenefitMember2019-01-012019-05-310001126328us-gaap:PensionPlansDefinedBenefitMember2019-01-012019-12-310001126328us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2019-01-012019-12-310001126328us-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:NonqualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:NonqualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328pfg:SegmentUSInsuranceSolutionsMember2021-01-012021-12-310001126328pfg:SegmentPrincipalInternationalMember2021-01-012021-12-310001126328pfg:SegmentUSInsuranceSolutionsMember2020-01-012020-12-310001126328pfg:SegmentPrincipalInternationalMember2020-01-012020-12-310001126328pfg:SegmentUSInsuranceSolutionsMember2019-01-012019-12-310001126328pfg:SegmentPrincipalInternationalMember2019-01-012019-12-310001126328us-gaap:DomesticCountryMember2021-12-310001126328us-gaap:DomesticCountryMember2020-12-310001126328us-gaap:StateAndLocalJurisdictionMember2021-12-310001126328us-gaap:ForeignCountryMember2021-12-310001126328us-gaap:StateAndLocalJurisdictionMember2020-12-310001126328us-gaap:ForeignCountryMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:DebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:TradingSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputLossSeverityMemberus-gaap:MarketApproachValuationTechniqueMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDefaultRateMemberus-gaap:MarketApproachValuationTechniqueMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MinimumMemberus-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:MaximumMemberus-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:TradingSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputLossSeverityMemberus-gaap:MarketApproachValuationTechniqueMember2021-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDefaultRateMemberus-gaap:MarketApproachValuationTechniqueMember2021-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2021-12-310001126328srt:WeightedAverageMemberus-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputLossSeverityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDefaultRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputComparabilityAdjustmentMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputLossSeverityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDefaultRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputLossSeverityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDefaultRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MinimumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MinimumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MinimumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputComparabilityAdjustmentMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MaximumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MaximumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:MaximumMemberus-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputComparabilityAdjustmentMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputLossSeverityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDefaultRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputLossSeverityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDefaultRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputLossSeverityMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:MeasurementInputDefaultRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328srt:WeightedAverageMemberus-gaap:FairValueInputsLevel3Memberpfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLongDurationInterestRateMemberus-gaap:ValuationTechniqueDiscountedCashFlowMember2020-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:USStatesAndPoliticalSubdivisionsMember2021-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CommercialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedDebtObligationsMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:USStatesAndPoliticalSubdivisionsMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:ForeignGovernmentDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CommercialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedDebtObligationsMember2021-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMember2021-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:ForeignGovernmentDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMember2021-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USStatesAndPoliticalSubdivisionsMember2021-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ForeignGovernmentDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2021-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CommercialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedDebtObligationsMember2021-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherDebtSecuritiesMember2020-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2020-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CommercialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedDebtObligationsMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:USStatesAndPoliticalSubdivisionsMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherDebtSecuritiesMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:ForeignGovernmentDebtSecuritiesMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CommercialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedDebtObligationsMember2020-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMember2020-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:ForeignGovernmentDebtSecuritiesMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USTreasuryAndGovernmentMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:USStatesAndPoliticalSubdivisionsMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:OtherDebtSecuritiesMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:ForeignGovernmentDebtSecuritiesMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CorporateDebtSecuritiesMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CommercialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMemberus-gaap:CollateralizedDebtObligationsMember2020-12-310001126328us-gaap:CollateralizedDebtObligationsMember2021-01-012021-12-310001126328us-gaap:OtherDebtSecuritiesMember2021-01-012021-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMember2021-01-012021-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMember2020-01-012020-12-310001126328us-gaap:CollateralizedDebtObligationsMember2020-01-012020-12-310001126328pfg:PrincipalInternationalChileMembersrt:MaximumMemberpfg:UnsecuredLineOfCreditMember2020-01-012021-12-310001126328srt:MinimumMemberpfg:NonRecourseMortgagesAndNotesPayableConsolidateMember2021-12-310001126328srt:MaximumMemberpfg:NonRecourseMortgagesAndNotesPayableConsolidateMember2021-12-310001126328srt:MinimumMemberpfg:NonRecourseMortgagesAndNotesPayableConsolidateMember2020-12-310001126328srt:MaximumMemberpfg:NonRecourseMortgagesAndNotesPayableConsolidateMember2020-12-310001126328pfg:Delaware2048TrustMemberpfg:SeniorNotesDue2048Memberpfg:ContingentFundingAgreement30YearMember2018-03-080001126328pfg:Delaware2028TrustMemberpfg:SeniorNotesDue2028Memberpfg:ContingentFundingAgreement10YearMember2018-03-080001126328pfg:NotesPayable2.125PercentDue2030Memberus-gaap:SeniorNotesMember2020-08-030001126328pfg:NotesPayable2.125PercentDue2030Memberus-gaap:SeniorNotesMember2020-06-120001126328pfg:NotesPayable3.7PercentDue2029Memberus-gaap:SeniorNotesMember2019-05-070001126328pfg:NotesPayable4.3PercentDue2046Memberus-gaap:SeniorNotesMember2016-11-100001126328pfg:NotesPayable3.1PercentDue2026Memberus-gaap:SeniorNotesMember2016-11-100001126328pfg:NotesPayable3.1PercentDue2026AndNotesPayable4.3PercentDue2046Memberus-gaap:SeniorNotesMember2016-11-100001126328pfg:NotesPayable4.7PercentDue2055Memberus-gaap:JuniorSubordinatedDebtMember2015-05-070001126328pfg:NotesPayable3.4PercentDue2025Memberus-gaap:SeniorNotesMember2015-05-070001126328pfg:NotesPayable4.35PercentDue2043Memberus-gaap:SeniorNotesMember2012-11-160001126328pfg:NotesPayable3.125PercentDue2023Memberus-gaap:SeniorNotesMember2012-11-160001126328pfg:NotesPayable1.85PercentDue2017Memberus-gaap:SeniorNotesMember2012-11-160001126328pfg:NotesPayable1.85PercentDue2017And3.125PercentDue2023And4.35PercentDue2043Memberus-gaap:SeniorNotesMember2012-11-160001126328pfg:NotesPayable4.625PercentDue2042Memberus-gaap:SeniorNotesMember2012-09-050001126328pfg:NotesPayable3.3PercentDue2022Memberus-gaap:SeniorNotesMember2012-09-050001126328pfg:NotesPayable3.3PercentDue2022And4.625PercentDue2042Memberus-gaap:SeniorNotesMember2012-09-050001126328pfg:NotesPayable6.05PercentDue2036IssuedDecember2006Memberus-gaap:SeniorNotesMember2006-12-050001126328pfg:NotesPayable6.05PercentDue2036IssuedOctober2006Memberus-gaap:SeniorNotesMember2006-10-160001126328pfg:NotesPayableFloatingRateDue2055Member2021-12-310001126328pfg:NotesPayable6.05PercentDue2036Member2021-12-310001126328pfg:NotesPayable4.625PercentDue2042Member2021-12-310001126328pfg:NotesPayable4.3PercentDue2046Member2021-12-310001126328pfg:NotesPayable4.35PercentDue2043Member2021-12-310001126328pfg:NotesPayable3.7PercentDue2029Member2021-12-310001126328pfg:NotesPayable3.4PercentDue2025Member2021-12-310001126328pfg:NotesPayable3.3PercentDue2022Member2021-12-310001126328pfg:NotesPayable3.1PercentDue2026Member2021-12-310001126328pfg:NotesPayable3.125PercentDue2023Member2021-12-310001126328pfg:NotesPayable2.125PercentDue2030Member2021-12-310001126328pfg:NotesPayableFloatingRateDue2055Member2020-12-310001126328pfg:NotesPayable6.05PercentDue2036Member2020-12-310001126328pfg:NotesPayable4.625PercentDue2042Member2020-12-310001126328pfg:NotesPayable4.3PercentDue2046Member2020-12-310001126328pfg:NotesPayable4.35PercentDue2043Member2020-12-310001126328pfg:NotesPayable3.7PercentDue2029Member2020-12-310001126328pfg:NotesPayable3.4PercentDue2025Member2020-12-310001126328pfg:NotesPayable3.3PercentDue2022Member2020-12-310001126328pfg:NotesPayable3.1PercentDue2026Member2020-12-310001126328pfg:NotesPayable3.125PercentDue2023Member2020-12-310001126328pfg:NotesPayable2.125PercentDue2030Member2020-12-310001126328pfg:NotesPayable4.7PercentDue2055Memberus-gaap:JuniorSubordinatedDebtMember2015-05-072015-05-070001126328us-gaap:CommonStockMember2021-01-012021-12-310001126328us-gaap:CommonStockMember2020-01-012020-12-310001126328us-gaap:CommonStockMember2019-01-012019-12-310001126328us-gaap:AccidentAndHealthInsuranceSegmentMember2021-01-012021-12-310001126328us-gaap:AccidentAndHealthInsuranceSegmentMember2020-01-012020-12-310001126328us-gaap:AccidentAndHealthInsuranceSegmentMember2019-01-012019-12-310001126328srt:ParentCompanyMembersrt:ReportableLegalEntitiesMember2019-12-310001126328srt:ParentCompanyMembersrt:ReportableLegalEntitiesMember2018-12-3100011263282018-12-310001126328us-gaap:USTreasuryAndGovernmentMember2021-12-310001126328us-gaap:USStatesAndPoliticalSubdivisionsMember2021-12-310001126328us-gaap:ResidentialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:OtherDebtSecuritiesMember2021-12-310001126328us-gaap:ForeignGovernmentDebtSecuritiesMember2021-12-310001126328us-gaap:CorporateDebtSecuritiesMember2021-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:CollateralizedDebtObligationsMember2021-12-310001126328us-gaap:USTreasuryAndGovernmentMember2020-12-310001126328us-gaap:USStatesAndPoliticalSubdivisionsMember2020-12-310001126328us-gaap:ResidentialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:OtherDebtSecuritiesMember2020-12-310001126328us-gaap:ForeignGovernmentDebtSecuritiesMember2020-12-310001126328us-gaap:CorporateDebtSecuritiesMember2020-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:CollateralizedDebtObligationsMember2020-12-310001126328us-gaap:LifeAndAnnuityInsuranceProductLineMember2021-01-012021-12-310001126328us-gaap:LifeAndAnnuityInsuranceProductLineMember2020-01-012020-12-310001126328us-gaap:LifeAndAnnuityInsuranceProductLineMember2019-01-012019-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:TradingSecuritiesMember2021-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:OtherDebtSecuritiesMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:CorporateDebtSecuritiesMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:CommercialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:CollateralizedDebtObligationsMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:TradingSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:TradingSecuritiesMemberus-gaap:OtherDebtSecuritiesMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:TradingSecuritiesMemberus-gaap:CommercialMortgageBackedSecuritiesMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:TradingSecuritiesMemberus-gaap:CollateralizedDebtObligationsMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:EquitySecuritiesMember2021-12-310001126328us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2021-12-310001126328pfg:VariableInterestEntityPrimaryBeneficiaryResidentialMortgageLoansMember2021-12-310001126328pfg:VariableInterestEntityPrimaryBeneficiaryRealEstateMember2021-12-310001126328pfg:VariableInterestEntityPrimaryBeneficiaryMandatoryRetirementSavingsMember2021-12-310001126328pfg:SegmentPrincipalGlobalInvestorsMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:OtherDebtSecuritiesMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:CorporateDebtSecuritiesMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:CommercialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:AvailableforsaleSecuritiesMemberus-gaap:CollateralizedDebtObligationsMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:TradingSecuritiesMemberus-gaap:ResidentialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:TradingSecuritiesMemberus-gaap:OtherDebtSecuritiesMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:TradingSecuritiesMemberus-gaap:CommercialMortgageBackedSecuritiesMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:TradingSecuritiesMemberus-gaap:CollateralizedDebtObligationsMember2020-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberus-gaap:EquitySecuritiesMember2020-12-310001126328us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2020-12-310001126328pfg:VariableInterestEntityPrimaryBeneficiaryResidentialMortgageLoansMember2020-12-310001126328pfg:VariableInterestEntityPrimaryBeneficiaryRealEstateMember2020-12-310001126328pfg:VariableInterestEntityPrimaryBeneficiaryMandatoryRetirementSavingsMember2020-12-310001126328pfg:SegmentPrincipalGlobalInvestorsMember2020-12-310001126328us-gaap:PensionPlansDefinedBenefitMember2020-01-012020-12-310001126328us-gaap:OtherIntangibleAssetsMember2021-01-012021-12-310001126328us-gaap:OtherIntangibleAssetsMember2020-01-012020-12-310001126328srt:MaximumMemberus-gaap:JuniorSubordinatedDebtMember2015-05-072015-05-070001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:OtherLimitedPartnershipAndFundInterestsMember2021-12-310001126328us-gaap:VariableInterestEntityNotPrimaryBeneficiaryMemberpfg:OtherLimitedPartnershipAndFundInterestsMember2020-12-310001126328us-gaap:SubsequentEventMember2022-01-012022-01-310001126328us-gaap:CommonStockMember2022-01-012022-01-310001126328us-gaap:CommonStockMember2021-06-012021-06-300001126328us-gaap:CommonStockMember2020-02-012020-02-290001126328us-gaap:CommonStockMember2018-11-012018-11-300001126328pfg:ContingentFundingAgreementMember2018-03-080001126328us-gaap:RetainedEarningsMember2021-01-012021-12-310001126328us-gaap:RetainedEarningsMember2020-01-012020-12-310001126328us-gaap:RetainedEarningsMember2019-01-012019-12-310001126328pfg:StockBasedCompensationPlansMember2021-01-012021-12-310001126328pfg:StockBasedCompensationPlansMember2020-01-012020-12-310001126328pfg:StockBasedCompensationPlansMember2019-01-012019-12-310001126328pfg:StockBasedCompensationDirectorsStockPlanStockIncentivePlanAmendedAndRestatedStockIncentivePlanDirectorsStockPlanMember2014-05-200001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMemberpfg:DiscountedCashFlowRealEstateMember2021-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowRealEstateMember2021-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowMortgageLoansMember2021-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputCreditSpreadMemberpfg:DiscountedCashFlowMortgageLoansMember2021-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputTerminalCapitalizationRateMemberpfg:DiscountedCashFlowRealEstateMember2021-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputMarketInterestRateMemberpfg:DiscountedCashFlowRealEstateDebtMember2021-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLoanToValueRatioMemberpfg:DiscountedCashFlowRealEstateDebtMember2021-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMemberpfg:DiscountedCashFlowRealEstateMember2021-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowRealEstateMember2021-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputTerminalCapitalizationRateMemberpfg:DiscountedCashFlowRealEstateMember2021-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputMarketInterestRateMemberpfg:DiscountedCashFlowRealEstateDebtMember2021-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLoanToValueRatioMemberpfg:DiscountedCashFlowRealEstateDebtMember2021-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMemberpfg:DiscountedCashFlowRealEstateMember2021-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowRealEstateMember2021-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputTerminalCapitalizationRateMemberpfg:DiscountedCashFlowRealEstateMember2021-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputMarketInterestRateMemberpfg:DiscountedCashFlowRealEstateDebtMember2021-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLoanToValueRatioMemberpfg:DiscountedCashFlowRealEstateDebtMember2021-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowMortgageLoansMember2021-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputCreditSpreadMemberpfg:DiscountedCashFlowMortgageLoansMember2021-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowMortgageLoansMember2020-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberpfg:DiscountedCashFlowMortgageLoansMember2020-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputCreditSpreadMemberpfg:DiscountedCashFlowMortgageLoansMember2020-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputTerminalCapitalizationRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputMarketInterestRateMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328srt:WeightedAverageMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLoanToValueRatioMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputTerminalCapitalizationRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputMarketInterestRateMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328srt:MinimumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLoanToValueRatioMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputTerminalCapitalizationRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputMarketInterestRateMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328srt:MaximumMemberpfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLoanToValueRatioMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowMortgageLoansMember2020-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountForLackOfMarketabilityMemberpfg:DiscountedCashFlowMortgageLoansMember2020-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputCreditSpreadMemberpfg:DiscountedCashFlowMortgageLoansMember2020-12-310001126328pfg:LongTermDisabilityGroupLifeWaiverMember2021-12-310001126328pfg:Delaware2048TrustMember2018-03-082018-03-080001126328pfg:Delaware2028TrustMember2018-03-082018-03-080001126328srt:ParentCompanyMembersrt:ReportableLegalEntitiesMemberus-gaap:NonqualifiedPlanMember2021-12-310001126328srt:ParentCompanyMembersrt:ReportableLegalEntitiesMemberus-gaap:NonqualifiedPlanMember2020-12-310001126328us-gaap:InterestRateContractMemberus-gaap:FairValueHedgingMemberpfg:NetInvestmentIncomeLossMember2021-01-012021-12-310001126328us-gaap:InterestRateContractMemberus-gaap:CashFlowHedgingMemberpfg:BenefitsClaimsAndSettlementExpensesMember2021-01-012021-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:CashFlowHedgingMemberpfg:NetInvestmentIncomeLossMember2021-01-012021-12-310001126328us-gaap:InterestRateContractMemberus-gaap:FairValueHedgingMemberpfg:NetInvestmentIncomeLossMember2020-01-012020-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:CashFlowHedgingMemberpfg:NetInvestmentIncomeLossMember2020-01-012020-12-310001126328us-gaap:InterestRateContractMemberus-gaap:FairValueHedgingMemberpfg:NetInvestmentIncomeLossMember2019-01-012019-12-310001126328us-gaap:ForeignExchangeContractMemberus-gaap:CashFlowHedgingMemberpfg:NetInvestmentIncomeLossMember2019-01-012019-12-310001126328pfg:Delaware2028TrustMemberpfg:ContingentFundingAgreement10YearMember2018-03-082018-03-080001126328srt:RetailSiteMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328srt:OtherPropertyMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328srt:OfficeBuildingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328srt:IndustrialPropertyMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328srt:HotelMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328srt:ApartmentBuildingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:WestSouthCentralMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:WestNorthCentralMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:SouthAtlanticMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:PacificMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:NewEnglandMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:MountainMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:MiddleAtlanticMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:InternationalMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:EastSouthCentralMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328pfg:EastNorthCentralMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMember2021-12-310001126328srt:RetailSiteMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328srt:OtherPropertyMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328srt:OfficeBuildingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328srt:IndustrialPropertyMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328srt:HotelMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328srt:ApartmentBuildingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:WestSouthCentralMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:WestNorthCentralMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:SouthAtlanticMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:PacificMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:NewEnglandMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:MountainMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:MiddleAtlanticMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:InternationalMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:EastSouthCentralMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:EastNorthCentralMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:Delaware2048TrustMemberpfg:ContingentFundingAgreement30YearMember2018-03-082018-03-080001126328pfg:SubsegmentIndividualLifeInsuranceMember2021-12-310001126328pfg:SubsegmentIndividualLifeInsuranceMember2020-12-310001126328pfg:SubsegmentIndividualLifeInsuranceMember2019-12-310001126328srt:WeightedAverageMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:RevenueMultiplesMemberus-gaap:MarketApproachValuationTechniqueMember2021-12-310001126328srt:MinimumMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:RevenueMultiplesMemberus-gaap:MarketApproachValuationTechniqueMember2021-12-310001126328srt:MaximumMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:RevenueMultiplesMemberus-gaap:MarketApproachValuationTechniqueMember2021-12-310001126328srt:WeightedAverageMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:WeightedAverageMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:ValuationTechniqueDiscountedCashFlowOtherInvestmentsMember2020-12-310001126328srt:WeightedAverageMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:WeightedAverageMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputCreditSpreadMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328srt:WeightedAverageMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:TerminalEarningsBeforeInterestTaxesDepreciationAndAmortizationMultipleMemberpfg:ValuationTechniqueDiscountedCashFlowOtherInvestmentsMember2020-12-310001126328srt:WeightedAverageMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:RevenueMultiplesMemberus-gaap:MarketApproachValuationTechniqueMember2020-12-310001126328srt:WeightedAverageMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputTerminalCapitalizationRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328srt:WeightedAverageMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLoanToValueRatioMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328srt:MinimumMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:ValuationTechniqueDiscountedCashFlowOtherInvestmentsMember2020-12-310001126328srt:MinimumMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:TerminalEarningsBeforeInterestTaxesDepreciationAndAmortizationMultipleMemberpfg:ValuationTechniqueDiscountedCashFlowOtherInvestmentsMember2020-12-310001126328srt:MinimumMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:RevenueMultiplesMemberus-gaap:MarketApproachValuationTechniqueMember2020-12-310001126328srt:MaximumMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:ValuationTechniqueDiscountedCashFlowOtherInvestmentsMember2020-12-310001126328srt:MaximumMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:TerminalEarningsBeforeInterestTaxesDepreciationAndAmortizationMultipleMemberpfg:ValuationTechniqueDiscountedCashFlowOtherInvestmentsMember2020-12-310001126328srt:MaximumMemberpfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:RevenueMultiplesMemberus-gaap:MarketApproachValuationTechniqueMember2020-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputLongTermRevenueGrowthRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputDiscountRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:MeasurementInputCreditSpreadMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputTerminalCapitalizationRateMemberpfg:DiscountedCashFlowRealEstateMember2020-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMemberpfg:MeasurementInputLoanToValueRatioMemberpfg:DiscountedCashFlowRealEstateDebtMember2020-12-310001126328us-gaap:AccumulatedOtherComprehensiveIncomeMember2021-01-012021-12-310001126328us-gaap:AccumulatedOtherComprehensiveIncomeMember2020-01-012020-12-310001126328us-gaap:AccumulatedOtherComprehensiveIncomeMember2019-01-012019-12-310001126328srt:ParentCompanyMembersrt:ReportableLegalEntitiesMember2021-12-310001126328srt:ParentCompanyMembersrt:ReportableLegalEntitiesMember2020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentEliminationsMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentRetirementAndIncomeSolutionsMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentEliminationsMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentRetirementAndIncomeSolutionsMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentEliminationsMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentRetirementAndIncomeSolutionsMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMember2019-01-012019-12-310001126328us-gaap:InterestRateContractMemberus-gaap:CashFlowHedgingMemberus-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember2019-01-012019-12-310001126328pfg:ContingentFundingAgreementMember2018-03-082018-03-0800011263282019-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:EstimateOfFairValueFairValueDisclosureMember2021-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:EstimateOfFairValueFairValueDisclosureMember2020-12-310001126328us-gaap:RestrictedStockUnitsRSUMember2021-01-012021-12-310001126328us-gaap:PerformanceSharesMember2021-01-012021-12-310001126328us-gaap:RestrictedStockUnitsRSUMember2020-01-012020-12-310001126328us-gaap:PerformanceSharesMember2020-01-012020-12-310001126328us-gaap:RestrictedStockUnitsRSUMember2019-01-012019-12-310001126328us-gaap:PerformanceSharesMember2019-01-012019-12-310001126328pfg:SegmentRetirementAndIncomeSolutionsMember2021-01-012021-12-310001126328pfg:SegmentPrincipalGlobalInvestorsMember2021-01-012021-12-310001126328pfg:SegmentRetirementAndIncomeSolutionsMember2020-01-012020-12-310001126328pfg:SegmentPrincipalGlobalInvestorsMember2020-01-012020-12-310001126328pfg:SegmentRetirementAndIncomeSolutionsMember2019-01-012019-12-310001126328pfg:SegmentPrincipalGlobalInvestorsMember2019-01-012019-12-310001126328us-gaap:InterestRateSwapMember2021-01-012021-12-310001126328pfg:FixedMaturitiesSecuritiesAvailableForSaleMember2021-12-310001126328pfg:FixedMaturitiesSecuritiesAvailableForSaleMember2020-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:DebtSecuritiesMember2021-01-012021-12-310001126328pfg:TradingSecuritiesMemberus-gaap:DebtSecuritiesMember2021-01-012021-12-310001126328us-gaap:PolicyLoansMember2021-01-012021-12-310001126328us-gaap:EquitySecuritiesMember2021-01-012021-12-310001126328us-gaap:DerivativeMember2021-01-012021-12-310001126328us-gaap:CashAndCashEquivalentsMember2021-01-012021-12-310001126328pfg:OtherInvestmentTypesMember2021-01-012021-12-310001126328pfg:MortgageLoansMember2021-01-012021-12-310001126328pfg:InvestmentsInRealEstateMember2021-01-012021-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:DebtSecuritiesMember2020-01-012020-12-310001126328pfg:TradingSecuritiesMemberus-gaap:DebtSecuritiesMember2020-01-012020-12-310001126328us-gaap:PolicyLoansMember2020-01-012020-12-310001126328us-gaap:EquitySecuritiesMember2020-01-012020-12-310001126328us-gaap:DerivativeMember2020-01-012020-12-310001126328us-gaap:CashAndCashEquivalentsMember2020-01-012020-12-310001126328pfg:OtherInvestmentTypesMember2020-01-012020-12-310001126328pfg:MortgageLoansMember2020-01-012020-12-310001126328pfg:InvestmentsInRealEstateMember2020-01-012020-12-310001126328us-gaap:AvailableforsaleSecuritiesMemberus-gaap:DebtSecuritiesMember2019-01-012019-12-310001126328us-gaap:PolicyLoansMember2019-01-012019-12-310001126328us-gaap:EquitySecuritiesMember2019-01-012019-12-310001126328us-gaap:DerivativeMember2019-01-012019-12-310001126328us-gaap:CashAndCashEquivalentsMember2019-01-012019-12-310001126328pfg:OtherInvestmentTypesMember2019-01-012019-12-310001126328pfg:MortgageLoansMember2019-01-012019-12-310001126328pfg:InvestmentsInRealEstateMember2019-01-012019-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMember2021-01-012021-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2011ProgramMember2011-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2006ProgramMember2006-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2001ProgramMember2001-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement1998ProgramMember1998-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2011ProgramMember2021-02-280001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2011ProgramMember2017-11-300001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2011ProgramMember2015-06-300001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreementsFederalHomeLoanBankDesMoinesMember2021-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2011ProgramMember2021-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2006ProgramMember2021-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement1998ProgramMember2021-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreementsFederalHomeLoanBankDesMoinesMember2020-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2011ProgramMember2020-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2006ProgramMember2020-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement2001ProgramMember2020-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberpfg:FundingAgreement1998ProgramMember2020-12-310001126328pfg:StandardPoorsBPlusAndBelowRatingMemberus-gaap:FinanceLeasesPortfolioSegmentMember2020-12-310001126328pfg:StandardPoorsBPlusAndBelowRatingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:StandardPoorsBBPlusThruBBMinusRatingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:StandardPoorsBBBPlusThruBBBMinusRatingMemberus-gaap:FinanceLeasesPortfolioSegmentMember2020-12-310001126328pfg:StandardPoorsBBBPlusThruBBBMinusRatingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:StandardPoorsAMinusAndAboveRatingMemberus-gaap:FinanceLeasesPortfolioSegmentMember2020-12-310001126328pfg:StandardPoorsAMinusAndAboveRatingMemberus-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328pfg:PerformingMemberus-gaap:ResidentialMortgageMember2020-12-310001126328pfg:NonperformingMemberus-gaap:ResidentialMortgageMember2020-12-310001126328us-gaap:ResidentialMortgageMember2020-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMember2020-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMember2020-12-310001126328us-gaap:FinanceLeasesPortfolioSegmentMember2021-01-012021-12-310001126328us-gaap:ResidentialMortgageMember2020-01-022020-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMember2020-01-022020-12-3100011263282020-01-022020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentSpecialtyBenefitsInsuranceMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentIndividualLifeInsuranceMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsSpreadMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentPrincipalInternationalMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentPrincipalGlobalInvestorsMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentCorporateMember2021-01-012021-12-310001126328us-gaap:MaterialReconcilingItemsMember2021-01-012021-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentSpecialtyBenefitsInsuranceMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentIndividualLifeInsuranceMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsSpreadMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentPrincipalInternationalMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentPrincipalGlobalInvestorsMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentCorporateMember2020-01-012020-12-310001126328us-gaap:MaterialReconcilingItemsMember2020-01-012020-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentSpecialtyBenefitsInsuranceMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentUSInsuranceSolutionsMemberpfg:SubsegmentIndividualLifeInsuranceMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsSpreadMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentRetirementAndIncomeSolutionsMemberpfg:SubsegmentRetirementAndIncomeSolutionsFeeMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentPrincipalInternationalMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentPrincipalGlobalInvestorsMember2019-01-012019-12-310001126328us-gaap:OperatingSegmentsMemberpfg:SegmentCorporateMember2019-01-012019-12-310001126328us-gaap:MaterialReconcilingItemsMember2019-01-012019-12-310001126328us-gaap:EquityMethodInvestmentsMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMember2021-01-012021-12-310001126328us-gaap:FairValueMeasurementsRecurringMember2020-01-012020-12-310001126328us-gaap:FairValueMeasurementsRecurringMember2019-01-012019-12-310001126328pfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMember2021-01-012021-12-310001126328pfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMember2020-01-012020-12-310001126328pfg:InvestmentAndUniversalLifeContractsMemberus-gaap:FairValueMeasurementsRecurringMember2019-01-012019-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-01-012021-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueMeasurementsRecurringMember2021-01-012021-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueMeasurementsRecurringMember2021-01-012021-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueMeasurementsRecurringMember2020-01-012020-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueMeasurementsRecurringMember2020-01-012020-12-310001126328us-gaap:FairValueMeasuredAtNetAssetValuePerShareMemberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328us-gaap:FairValueMeasuredAtNetAssetValuePerShareMemberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-01-012020-12-310001126328pfg:TradingSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMember2020-01-012020-12-310001126328pfg:SeparateAccountAssetsMemberus-gaap:FairValueMeasurementsRecurringMember2019-01-012019-12-310001126328us-gaap:USStatesAndPoliticalSubdivisionsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-01-012021-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-01-012021-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-01-012021-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-01-012021-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2021-01-012021-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-01-012020-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-01-012020-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-01-012020-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2020-01-012020-12-310001126328us-gaap:OtherDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-01-012019-12-310001126328us-gaap:DebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-01-012019-12-310001126328us-gaap:CorporateDebtSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-01-012019-12-310001126328us-gaap:CommercialMortgageBackedSecuritiesMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-01-012019-12-310001126328us-gaap:CollateralizedDebtObligationsMemberus-gaap:FairValueMeasurementsRecurringMemberus-gaap:AvailableforsaleSecuritiesMember2019-01-012019-12-310001126328pfg:InvestmentsOtherMemberus-gaap:FairValueMeasurementsRecurringMember2019-01-012019-12-310001126328us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2021-01-012021-12-310001126328us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2020-01-012020-12-310001126328us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember2019-01-012019-12-310001126328pfg:EmployeeStockPurchasePlanMember2021-12-310001126328pfg:EmployeeStockPurchasePlanMember2022-01-012022-01-010001126328srt:ParentCompanyMembersrt:ReportableLegalEntitiesMember2021-01-012021-12-310001126328srt:ParentCompanyMembersrt:ReportableLegalEntitiesMember2020-01-012020-12-310001126328srt:ParentCompanyMembersrt:ReportableLegalEntitiesMember2019-01-012019-12-310001126328pfg:SubsidiariesPrincipalLifeInsuranceCompanyMember2021-01-012021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328us-gaap:FairValueMeasurementsRecurringMember2021-12-310001126328us-gaap:FairValueInputsLevel3Memberus-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328us-gaap:FairValueMeasurementsRecurringMember2020-12-310001126328us-gaap:StockOptionMember2021-12-310001126328us-gaap:InterestRateSwapMember2021-12-310001126328us-gaap:ForeignExchangeForwardMember2021-12-310001126328us-gaap:CurrencySwapMember2021-12-310001126328us-gaap:CreditDefaultSwapMember2021-12-310001126328pfg:InterestRateOptionsMember2021-12-310001126328pfg:InterestRateForwardsMember2021-12-310001126328us-gaap:StockOptionMember2020-12-310001126328us-gaap:InterestRateSwapMember2020-12-310001126328us-gaap:ForeignExchangeForwardMember2020-12-310001126328us-gaap:CurrencySwapMember2020-12-310001126328us-gaap:CreditDefaultSwapMember2020-12-310001126328pfg:InterestRateOptionsMember2020-12-310001126328pfg:InterestRateForwardsMember2020-12-310001126328us-gaap:QualifiedPlanMemberpfg:DefinedContributionPlanGrandfatheredChoiceParticipantMember2021-01-012021-12-310001126328us-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-01-012021-12-310001126328us-gaap:NonqualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2021-01-012021-12-310001126328us-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-01-012020-12-310001126328us-gaap:NonqualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2020-01-012020-12-310001126328us-gaap:QualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2019-01-012019-12-310001126328us-gaap:NonqualifiedPlanMemberus-gaap:PensionPlansDefinedBenefitMember2019-01-012019-12-310001126328us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-01-012021-12-310001126328us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-01-012020-12-310001126328us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-01-010001126328us-gaap:PensionPlansDefinedBenefitMember2021-12-310001126328us-gaap:PensionPlansDefinedBenefitMember2020-12-310001126328us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2021-12-310001126328us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember2020-12-310001126328us-gaap:PensionPlansDefinedBenefitMember2021-01-012021-12-310001126328pfg:LongTermCarePlansMember2020-04-012020-06-300001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberus-gaap:CorporateDebtSecuritiesMember2021-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberus-gaap:CommercialMortgageBackedSecuritiesMember2021-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberus-gaap:CollateralizedDebtObligationsMember2021-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberus-gaap:CorporateDebtSecuritiesMember2020-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberus-gaap:CommercialMortgageBackedSecuritiesMember2020-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMemberus-gaap:CollateralizedDebtObligationsMember2020-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMember2021-12-310001126328pfg:PrincipalLifeInsuranceCompanyConsolidatedMember2020-12-310001126328us-gaap:CorporateDebtSecuritiesMember2021-01-012021-12-310001126328us-gaap:CorporateDebtSecuritiesMember2020-01-012020-12-310001126328pfg:NonRecourseMortgagesAndNotesPayableConsolidateMember2021-12-310001126328pfg:NonRecourseMortgagesAndNotesPayableConsolidateMember2020-12-310001126328us-gaap:ResidentialMortgageMember2021-01-012021-12-310001126328us-gaap:CommercialRealEstatePortfolioSegmentMember2021-01-012021-12-310001126328pfg:NonperformingMemberus-gaap:ResidentialMortgageMember2021-01-012021-12-310001126328srt:StandardPoorsBBBRatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:CorporateDebtSecuritiesMember2021-01-012021-12-310001126328srt:StandardPoorsARatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:SovereignDebtMember2021-01-012021-12-310001126328srt:StandardPoorsARatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:CorporateDebtSecuritiesMember2021-01-012021-12-310001126328us-gaap:CreditDefaultSwapMember2021-01-012021-12-310001126328srt:StandardPoorsBBBRatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:SovereignDebtMember2020-01-012020-12-310001126328srt:StandardPoorsBBBRatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:CorporateDebtSecuritiesMember2020-01-012020-12-310001126328srt:StandardPoorsARatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:SovereignDebtMember2020-01-012020-12-310001126328srt:StandardPoorsARatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:CorporateDebtSecuritiesMember2020-01-012020-12-310001126328us-gaap:CreditDefaultSwapMember2020-01-012020-12-310001126328srt:StandardPoorsBBBRatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:CorporateDebtSecuritiesMember2021-12-310001126328srt:StandardPoorsARatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:SovereignDebtMember2021-12-310001126328srt:StandardPoorsARatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:CorporateDebtSecuritiesMember2021-12-310001126328us-gaap:CreditDefaultSwapMember2021-12-310001126328srt:StandardPoorsBBBRatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:SovereignDebtMember2020-12-310001126328srt:StandardPoorsBBBRatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:CorporateDebtSecuritiesMember2020-12-310001126328srt:StandardPoorsARatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:SovereignDebtMember2020-12-310001126328srt:StandardPoorsARatingMemberpfg:SingleNameCreditDefaultSwapsMemberus-gaap:CorporateDebtSecuritiesMember2020-12-310001126328us-gaap:CreditDefaultSwapMember2020-12-310001126328us-gaap:VariableInterestEntityPrimaryBeneficiaryMember2021-12-310001126328us-gaap:VariableInterestEntityPrimaryBeneficiaryMember2020-12-310001126328pfg:SegmentUSInsuranceSolutionsMember2021-12-310001126328pfg:SegmentRetirementAndIncomeSolutionsMember2021-12-310001126328pfg:SegmentPrincipalInternationalMember2021-12-310001126328pfg:SegmentCorporateMember2021-12-310001126328pfg:SegmentUSInsuranceSolutionsMember2020-12-310001126328pfg:SegmentRetirementAndIncomeSolutionsMember2020-12-310001126328pfg:SegmentPrincipalInternationalMember2020-12-310001126328pfg:SegmentCorporateMember2020-12-310001126328us-gaap:DerivativeFinancialInstrumentsAssetsMember2021-12-310001126328pfg:ReverseRepurchaseAgreementMember2021-12-310001126328us-gaap:DerivativeFinancialInstrumentsAssetsMember2020-12-310001126328pfg:ReverseRepurchaseAgreementMember2020-12-310001126328us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember2021-12-310001126328us-gaap:DerivativeFinancialInstrumentsLiabilitiesMember2020-12-310001126328pfg:EmployeeStockPurchasePlanMember2021-01-012021-12-310001126328pfg:EmployeeStockPurchasePlanMember2020-01-012020-12-310001126328pfg:EmployeeStockPurchasePlanMember2019-01-012019-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:EstimateOfFairValueFairValueDisclosureMember2021-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:EstimateOfFairValueFairValueDisclosureMember2021-12-310001126328us-gaap:EstimateOfFairValueFairValueDisclosureMember2021-12-310001126328us-gaap:CarryingReportedAmountFairValueDisclosureMember2021-12-310001126328us-gaap:FairValueInputsLevel2Memberus-gaap:EstimateOfFairValueFairValueDisclosureMember2020-12-310001126328us-gaap:FairValueInputsLevel1Memberus-gaap:EstimateOfFairValueFairValueDisclosureMember2020-12-310001126328us-gaap:EstimateOfFairValueFairValueDisclosureMember2020-12-310001126328us-gaap:CarryingReportedAmountFairValueDisclosureMember2020-12-310001126328us-gaap:CommercialPaperMember2021-12-310001126328us-gaap:CommercialPaperMember2020-12-310001126328