1.0.0.3 false Consolidated Statements of Cash Flows (USD $) In Millions false 1 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 2 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 4 Operating activities 2 us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false No definition available. false 5 Net income 3 us-gaap_ProfitLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 490800000 490.8 false false 2 true true 469400000 469.4 false false No definition available. No authoritative reference available. false 6 Adjustments to reconcile net income to net cash provided by operating activities: 3 us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false No definition available. false 7 Amortization of deferred policy acquisition costs 4 us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 70400000 70.4 false false 2 false true 212600000 212.6 false false No definition available. No authoritative reference available. false 8 Additions to deferred policy acquisition costs 4 us-gaap_DeferredPolicyAcquisitionCostsAdditions us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -361000000 -361.0 false false 2 false true -540100000 -540.1 false false No definition available. No authoritative reference available. false 9 Accrued investment income 4 us-gaap_IncreaseDecreaseInAccruedInvestmentIncomeReceivable us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 8000000 8.0 false false 2 false true -32800000 -32.8 false false No definition available. No authoritative reference available. false 10 Net cash flows from trading securities 4 us-gaap_ProceedsFromPaymentsForTradingSecurities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -101000000 -101.0 false false 2 false true -451900000 -451.9 false false No definition available. No authoritative reference available. false 11 Premiums due and other receivables 4 us-gaap_IncreaseDecreaseInReceivables us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -106100000 -106.1 false false 2 false true 10000000 10.0 false false No definition available. No authoritative reference available. false 12 Contractholder and policyholder liabilities and dividends 4 us-gaap_IncreaseDecreaseInInsuranceLiabilities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1189600000 1189.6 false false 2 false true 1747000000 1747.0 false false No definition available. No authoritative reference available. false 13 Current and deferred income taxes (benefits) 4 pfg_IncreaseDecreaseInAccruedAndDeferredIncomeTaxes pfg false debit duration monetary The net change during the reporting period of current accrued and deferred income taxes payable. Accrued income taxes... false false false false false false false false false 1 false true 128000000 128.0 false false 2 false true -93500000 -93.5 false false The net change during the reporting period of current accrued and deferred income taxes payable. Accrued income taxes payable are defined as the carrying amount as of the balance sheet date of the unpaid sum of the known and estimated amounts payable to satisfy all currently due domestic and foreign income tax obligations. In theory, the sum represents amounts due to tax jurisdictions based on tax returns as if they were ready and available for filing on and as of the balance sheet date, plus penalties pertaining to amounts of tax uncertainties. Deferred income taxes payable represent the temporary differences that result from income (loss) that is recognized for accounting purposes but not for tax purposes and vice versa. No authoritative reference available. false 14 Net realized capital losses 4 us-gaap_GainLossOnInvestments us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 285100000 285.1 false false 2 false true 468100000 468.1 false false No definition available. No authoritative reference available. false 15 Depreciation and amortization expense 4 us-gaap_DepreciationAmortizationAndAccretionNet us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 104400000 104.4 false false 2 false true 105400000 105.4 false false No definition available. No authoritative reference available. false 16 Mortgage loans held for sale, acquired or originated 4 us-gaap_PaymentsForOriginationAndPurchasesOfLoansHeldForSale us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -41700000 -41.7 false false 2 false true -56400000 -56.4 false false No definition available. No authoritative reference available. false 17 Mortgage loans held for sale, sold or repaid, net of gain 4 us-gaap_ProceedsFromSaleAndCollectionOfLoansHeldforsale us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 49400000 49.4 false false 2 false true 52100000 52.1 false false No definition available. No authoritative reference available. false 18 Real estate acquired through operating activities 4 us-gaap_PaymentsToAcquireHeldForSaleRealEstate us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -25100000 -25.1 false false 2 false true -50700000 -50.7 false false No definition available. No authoritative reference available. false 19 Real estate sold through operating activities 4 us-gaap_ProceedsFromSaleOfWhollyOwnedRealEstateAndRealEstateAcquiredInSettlementOfLoans us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 3200000 3.2 false false 2 false true 14600000 14.6 false false No definition available. No authoritative reference available. false 20 Stock-based compensation 4 us-gaap_ShareBasedCompensation us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 26900000 26.9 false false 2 false true 32800000 32.8 false false No definition available. No authoritative reference available. false 21 Other 4 us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesOther us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 73500000 73.5 false false 2 false true -19400000 -19.4 false false No definition available. No authoritative reference available. false 22 Net adjustments 4 us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1303600000 1303.6 false false 2 false true 1397800000 1397.8 false false No definition available. No authoritative reference available. true 23 Net cash provided by operating activities 4 us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 1794400000 1794.4 false false 2 false true 1867200000 1867.2 false false No definition available. No authoritative reference available. true 24 Investing activities 2 us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false No definition available. false 25 Available-for-sale securities: purchases 3 us-gaap_PaymentsToAcquireAvailableForSaleSecurities us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -6600700000 -6600.7 false false 2 false true -6205600000 -6205.6 false false No definition available. No authoritative reference available. false 26 Available-for-sale securities: sales 3 us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 3770500000 3770.5 false false 2 false true 524500000 524.5 false false No definition available. No authoritative reference available. false 27 Available-for-sale securities: maturities 3 us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 3146000000 3146.0 false false 2 false true 2483700000 2483.7 false false No definition available. No authoritative reference available. false 28 Mortgage loans acquired or originated 3 us-gaap_PaymentsToAcquireMortgageNotesReceivable us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -271800000 -271.8 false false 2 false true -1682300000 -1682.3 false false No definition available. No authoritative reference available. false 29 Mortgage loans sold or repaid 3 us-gaap_ProceedsFromSaleAndCollectionOfMortgageNotesReceivable us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1247200000 1247.2 false false 2 false true 1041800000 1041.8 false false No definition available. No authoritative reference available. false 30 Real estate acquired 3 us-gaap_PaymentsToAcquireRealEstateHeldForInvestment us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -50200000 -50.2 false false 2 false true -20600000 -20.6 false false No definition available. No authoritative reference available. false 31 Real estate sold 3 us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 22100000 22.1 false false 2 false true 68700000 68.7 false false No definition available. No authoritative reference available. false 32 Net purchases of property and equipment 3 pfg_PaymentsToAcquirePropertyPlantAndEquipmentNet pfg false credit duration monetary The net cash inflow/outflow associated with the acquisition, sales and disposals of property, plant and equipment, and other... false false false false false false false false false 1 false true -20600000 -20.6 false false 2 false true -83300000 -83.3 false false The net cash inflow/outflow associated with the acquisition, sales and disposals of property, plant and equipment, and other productive assets, including intangible assets for software. No authoritative reference available. false 33 Purchases of interest in subsidiaries, net of cash acquired 3 us-gaap_PaymentsToAcquireInterestInSubsidiariesAndAffiliates us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -45700000 -45.7 false false 2 false true -20300000 -20.3 false false No definition available. No authoritative reference available. false 34 Net change in other investments 3 us-gaap_PaymentsForProceedsFromOtherInvestingActivities us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -40600000 -40.6 false false 2 false true -124900000 -124.9 false false No definition available. No authoritative reference available. false 35 Net cash provided by (used in) investing activities 3 us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1156200000 1156.2 false false 2 false true -4018300000 -4018.3 false false No definition available. No authoritative reference available. true 36 Financing activities 2 us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false No definition available. false 37 Issuance of common stock 3 us-gaap_ProceedsFromIssuanceOfCommonStock us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1123000000 1123.0 false false 2 false true 31500000 31.5 false false No definition available. No authoritative reference available. false 38 Acquisition of treasury stock 3 us-gaap_PaymentsForRepurchaseOfCommonStock us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -4100000 -4.1 false false 2 false true -6400000 -6.4 false false No definition available. No authoritative reference available. false 39 Proceeds from financing element derivatives 3 pfg_ProceedsFromFinancingElementDerivatives pfg false debit duration monetary The cash inflow from financing element derivatives. false false false false false false false false false 1 false true 121300000 121.3 false false 2 false true 130600000 130.6 false false The cash inflow from financing element derivatives. No authoritative reference available. false 40 Payments for financing element derivatives 3 pfg_PaymentsForFinancingElementDerivatives pfg false credit duration monetary The cash outflow from financing element derivatives. false false false false false false false false false 1 false true -57700000 -57.7 false false 2 false true -91300000 -91.3 false false The cash outflow from financing element derivatives. No authoritative reference available. false 41 Excess tax benefits from share-based payment arrangements 3 us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 200000 0.2 false false 2 false true 2800000 2.8 false false No definition available. No authoritative reference available. false 42 Dividends to preferred stockholders 3 us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -24700000 -24.7 false false 2 false true -24700000 -24.7 false false No definition available. No authoritative reference available. false 43 Issuance of long-term debt 3 us-gaap_ProceedsFromIssuanceOfLongTermDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 745100000 745.1 false false 2 false true 6400000 6.4 false false No definition available. No authoritative reference available. false 44 Principal repayments of long-term debt 3 us-gaap_RepaymentsOfLongTermDebt us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -465900000 -465.9 false false 2 false true -17300000 -17.3 false false No definition available. No authoritative reference available. false 45 Net proceeds (repayments) of short-term borrowings 3 us-gaap_ProceedsFromRepaymentsOfShortTermDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -397400000 -397.4 false false 2 false true 63900000 63.9 false false No definition available. No authoritative reference available. false 46 Investment contract deposits 3 us-gaap_AdditionsToContractHoldersFunds us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 3438200000 3438.2 false false 2 false true 9852400000 9852.4 false false No definition available. No authoritative reference available. false 47 Investment contract withdrawals 3 us-gaap_WithdrawalFromContractHoldersFunds us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -6871100000 -6871.1 false false 2 false true -7160600000 -7160.6 false false No definition available. No authoritative reference available. false 48 Net increase in banking operation deposits 3 us-gaap_IncreaseDecreaseInDeposits us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 80200000 80.2 false false 2 false true 293000000 293.0 false false No definition available. No authoritative reference available. false 49 Other 3 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -4500000 -4.5 false false 2 false true -4600000 -4.6 false false No definition available. No authoritative reference available. false 50 Net cash provided by (used in) financing activities 3 us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -2317400000 -2317.4 false false 2 false true 3075700000 3075.7 false false No definition available. No authoritative reference available. true 51 Net increase in cash and cash equivalents 2 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 633200000 633.2 false false 2 false true 924600000 924.6 false false No definition available. No authoritative reference available. true 52 Cash and cash equivalents at beginning of period 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false true false false 1 false true 2608000000 2608.0 false false 2 false true 1344400000 1344.4 false false No definition available. No authoritative reference available. false 53 Cash and cash equivalents at end of period 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false true false 1 true true 3241200000 3241.2 false false 2 true true 2269000000 2269.0 false false No definition available. No authoritative reference available. false false 2 50 false HundredThousands UnKnown UnKnown false true