1.0.0.3 false Consolidated Statements of Operations (USD $) In Millions, except Per Share data 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 false 3 $ 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 4 $ 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 Revenues 2 us-gaap_RevenuesAbstract 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 3 false false 0 0 false false 4 false false 0 0 false false No definition available. false 5 Premiums and other considerations 3 us-gaap_PremiumsEarnedNet us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 932900000 932.9 false false 2 true true 1049700000 1049.7 false false 3 true true 2820500000 2820.5 false false 4 true true 3258900000 3258.9 false false No definition available. No authoritative reference available. false 6 Fees and other revenues 3 us-gaap_FeesAndCommissions us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 550700000 550.7 false false 2 false true 599000000 599.0 false false 3 false true 1539400000 1539.4 false false 4 false true 1834900000 1834.9 false false No definition available. No authoritative reference available. false 7 Net investment income 3 us-gaap_NetInvestmentIncome us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 853300000 853.3 false false 2 false true 1079700000 1079.7 false false 3 false true 2541900000 2541.9 false false 4 false true 3030900000 3030.9 false false No definition available. No authoritative reference available. false 8 Net realized capital gains (losses), excluding impairment losses on available-for-sale securities 3 pfg_NetGainLossExcludingAvailableForSaleImpairments pfg false credit duration monetary This item represents the net realized and unrealized gains (losses), excluding impairment losses on available-for-sale... false false false false false false false false false 1 false true 50600000 50.6 false false 2 false true -20900000 -20.9 false false 3 false true 62500000 62.5 false false 4 false true -145000000 -145.0 false false This item represents the net realized and unrealized gains (losses), excluding impairment losses on available-for-sale securities, included in net income for the period as the result of selling or holding invested assets. This item includes the net gain or loss realized from the sale, exchange, redemption or retirement of securities and the unrealized holding gain or loss for certain invested assets. This item excludes other than temporary impairments on available-for-sale debt and equity securities. No authoritative reference available. false 9 Total other-than-temporary impairment losses on available-for-sale securities 3 pfg_OtherThanTemporaryImpairmentLossesInvestmentsAvailableForSaleSecurities pfg false debit duration monetary The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less... false false false false false false false false false 1 false true -162500000 -162.5 false false 2 false true -209700000 -209.7 false false 3 false true -510000000 -510.0 false false 4 false true -323100000 -323.1 false false The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income. No authoritative reference available. false 10 Portion of impairment losses on fixed maturities, available-for-sale recognized in other comprehensive income 3 pfg_OtherThanTemporaryImpairmentLossesInvestmentsPortionInOtherComprehensiveIncomeLossBeforeTaxIncludingPortionAttributableToNoncontrollingInterest pfg false debit duration monetary The amount of other than temporary impairment loss on a debt security, categorized as either Available-for-sale or... false false false false false false false false false 1 false true 45300000 45.3 false false 2 false false 0 0 false false 3 false true 162400000 162.4 false false 4 false false 0 0 false false The amount of other than temporary impairment loss on a debt security, categorized as either Available-for-sale or Held-to-maturity, related to factors other than credit losses when the entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis. This amount, which includes the portion attributable to the noncontrolling interest, if any, is deducted from the total impairment losses of investments (before taxes) presented on the income statement; this amount is also referred to as the amount incurred by the reporting entity or the consolidated entity. No authoritative reference available. false 11 Net impairment losses on available-for-sale securities 3 pfg_NetImpairmentLossesOnAvailableForSaleSecurities pfg false debit duration monetary This item represents the amount of loss recognized for other than temporary impairments of investments in debt and equity... false false false false false false false false false 1 false true -117200000 -117.2 false false 2 false true -209700000 -209.7 false false 3 false true -347600000 -347.6 false false 4 false true -323100000 -323.1 false false This item represents the amount of loss recognized for other than temporary impairments of investments in debt and equity securities, net of noncredit impairment losses on certain debt securities that are recognized in other comprehensive income. No authoritative reference available. true 12 Net realized capital losses 3 us-gaap_GainLossOnInvestments us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -66600000 -66.6 false false 2 false true -230600000 -230.6 false false 3 false true -285100000 -285.1 false false 4 false true -468100000 -468.1 false false No definition available. No authoritative reference available. true 13 Total revenues 3 us-gaap_Revenues us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 2270300000 2270.3 false false 2 false true 2497800000 2497.8 false false 3 false true 6616700000 6616.7 false false 4 false true 7656600000 7656.6 false false No definition available. No authoritative reference available. true 14 Expenses 2 us-gaap_BenefitsLossesAndExpensesAbstract 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 3 false false 0 0 false false 4 false false 0 0 false false No definition available. false 15 Benefits, claims and settlement expenses 3 us-gaap_PolicyholderBenefitsAndClaimsIncurredNet us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1317100000 1317.1 false false 2 false true 1597200000 1597.2 false false 3 false true 3958000000 3958.0 false false 4 false true 4703200000 4703.2 false false No definition available. No authoritative reference available. false 16 Dividends to policyholders 3 us-gaap_PolicyholderDividends us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 61900000 61.9 false false 2 false true 70400000 70.4 false false 3 false true 188300000 188.3 false false 4 false true 210200000 210.2 false false No definition available. No authoritative reference available. false 17 Operating expenses 3 pfg_OperatingExpensesIncludingDeferredAcquisitionCostsCapitalizationAndAmortization pfg false debit duration monetary Expenses other than those for payments of benefits, claims and policyholder dividends that are incurred related to the... false false false false false false false false false 1 false true 643000000 643.0 false false 2 false true 723700000 723.7 false false 3 false true 1894100000 1894.1 false false 4 false true 2217000000 2217.0 false false Expenses other than those for payments of benefits, claims and policyholder dividends that are incurred related to the operations of the company. Includes commission expense, capitalization of deferred policy acquisitions costs ("DPAC"), amortization of DPAC, depreciation and amortization expense, interest expense on corporate debt, compensation costs and other general and administrative expenses. No authoritative reference available. false 18 Total expenses 3 us-gaap_BenefitsLossesAndExpenses us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 2022000000 2022.0 false false 2 false true 2391300000 2391.3 false false 3 false true 6040400000 6040.4 false false 4 false true 7130400000 7130.4 false false No definition available. No authoritative reference available. true 19 Income before income taxes 2 pfg_IncomeLossFromContinuingOperationsBeforeIncomeTaxes pfg false credit duration monetary The sum of income (expense), including income (expense) attributable to the noncontrolling interest, before income taxes for... false false false false false false false false false 1 false true 248300000 248.3 false false 2 false true 106500000 106.5 false false 3 false true 576300000 576.3 false false 4 false true 526200000 526.2 false false The sum of income (expense), including income (expense) attributable to the noncontrolling interest, before income taxes for continuing operations. No authoritative reference available. true 20 Income taxes (benefits) 2 us-gaap_IncomeTaxExpenseBenefit us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 44100000 44.1 false false 2 false true -2200000 -2.2 false false 3 false true 85500000 85.5 false false 4 false true 56800000 56.8 false false No definition available. No authoritative reference available. false 21 Net income 2 us-gaap_ProfitLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 204200000 204.2 false false 2 false true 108700000 108.7 false false 3 false true 490800000 490.8 false false 4 false true 469400000 469.4 false false No definition available. No authoritative reference available. true 22 Net income attributable to noncontrolling interest 2 us-gaap_NetIncomeLossAttributableToNoncontrollingInterest us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 11300000 11.3 false false 2 false true 10400000 10.4 false false 3 false true 18300000 18.3 false false 4 false true 12100000 12.1 false false No definition available. No authoritative reference available. false 23 Net income attributable to Principal Financial Group, Inc. 2 us-gaap_NetIncomeLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 192900000 192.9 false false 2 false true 98300000 98.3 false false 3 false true 472500000 472.5 false false 4 false true 457300000 457.3 false false No definition available. No authoritative reference available. true 24 Preferred stock dividends 2 us-gaap_PreferredStockDividends us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 8200000 8.2 false false 2 false true 8200000 8.2 false false 3 false true 24700000 24.7 false false 4 false true 24700000 24.7 false false No definition available. No authoritative reference available. false 25 Net income available to common stockholders 2 us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 184700000 184.7 false false 2 true true 90100000 90.1 false false 3 true true 447800000 447.8 false false 4 true true 432600000 432.6 false false No definition available. No authoritative reference available. true 26 Earnings per common share 2 us-gaap_EarningsPerShareAbstract 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 3 false false 0 0 false false 4 false false 0 0 false false No definition available. false 27 Basic earnings per common share (in dollars per share) 3 us-gaap_EarningsPerShareBasic us-gaap true na duration decimal No definition available. false false false false false false false false true 1 true true 0.58 0.58 false false 2 true true 0.35 0.35 false false 3 true true 1.54 1.54 false false 4 true true 1.67 1.67 false false No definition available. No authoritative reference available. true 28 Diluted earnings per common share (in dollars per share) 3 us-gaap_EarningsPerShareDiluted us-gaap true na duration decimal No definition available. false false false false false false false false true 1 true true 0.57 0.57 false false 2 true true 0.35 0.35 false false 3 true true 1.54 1.54 false false 4 true true 1.66 1.66 false false No definition available. No authoritative reference available. true false 4 25 false HundredThousands UnKnown Hundreds false true