v3.26.1
Derivative Financial Instruments - Effect of Hedges on Consolidated Statements of Operations (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Gains (losses) recognized for hedging relationships        
Net investment income (loss) $ 1,301.8 $ 1,162.8 $ 2,500.8 $ 2,328.5
Net realized capital gains (losses) [1] 109.7 5.4 (12.4) (111.7)
Benefits, claims and settlement expenses 1,992.1 1,839.9 3,603.2 4,059.9
Fair Value Hedges | Location, Statement of Income, Balance [Axis]: pfg:BenefitsClaimsAndSettlementExpenses        
Gains (losses) recognized for hedging relationships        
Total gain (loss) recognized for hedging relationships 3.4 (9.4) 2.9 (14.7)
Fair Value Hedges | Location, Statement of Income, Balance [Axis]: pfg:NetInvestmentIncomeLoss        
Gains (losses) recognized for hedging relationships        
Total gain (loss) recognized for hedging relationships 6.5 10.7 14.1 23.4
Fair Value Hedges | Interest rate contracts | Location, Statement of Income, Balance [Axis]: pfg:BenefitsClaimsAndSettlementExpenses        
Gains (losses) recognized for hedging relationships        
Gain (loss) recognized on hedged item 36.8 16.2 64.9 51.7
Gain (loss) recognized on derivatives (33.9) (20.6) (62.6) (56.6)
Amounts related to periodic settlements on derivatives 0.5 (5.0) 0.6 (9.8)
Fair Value Hedges | Interest rate contracts | Location, Statement of Income, Balance [Axis]: pfg:NetInvestmentIncomeLoss        
Gains (losses) recognized for hedging relationships        
Gain (loss) recognized on hedged item (8.0) 15.0 (10.7) 42.4
Gain (loss) recognized on derivatives 6.9 (16.4) 10.1 (42.5)
Amortization of hedged item basis adjustments 1.7 1.3 2.3 1.9
Amounts related to periodic settlements on derivatives 5.2 10.0 10.9 20.1
Fair Value Hedges | Foreign exchange contracts | Location, Statement of Income, Balance [Axis]: pfg:NetInvestmentIncomeLoss        
Gains (losses) recognized for hedging relationships        
Amounts related to periodic settlements on derivatives 0.7 0.8 1.5 1.5
Fair Value Hedges | Foreign exchange contracts | Location, Statement of Income, Balance [Axis]: pfg:NetRealizedCapitalGainsLosses        
Gains (losses) recognized for hedging relationships        
Gain (loss) recognized on hedged item (2.0) 17.2 (7.5) 25.0
Gain (loss) recognized on derivatives 2.0 (17.2) 7.5 (25.0)
Cash Flow Hedges | Location, Statement of Income, Balance [Axis]: pfg:BenefitsClaimsAndSettlementExpenses        
Gains (losses) recognized for hedging relationships        
Benefits, claims and settlement expenses (0.1)      
Total gain (loss) recognized for hedging relationships     (0.1) (0.1)
Cash Flow Hedges | Location, Statement of Income, Balance [Axis]: pfg:NetInvestmentIncomeLoss        
Gains (losses) recognized for hedging relationships        
Total gain (loss) recognized for hedging relationships 8.8 9.5 17.1 18.6
Cash Flow Hedges | Location, Statement of Income, Balance [Axis]: pfg:NetRealizedCapitalGainsLosses        
Gains (losses) recognized for hedging relationships        
Total gain (loss) recognized for hedging relationships   2.7 (0.1) 2.7
Cash Flow Hedges | Interest rate contracts | Location, Statement of Income, Balance [Axis]: pfg:BenefitsClaimsAndSettlementExpenses        
Gains (losses) recognized for hedging relationships        
Gain (loss) reclassified from AOCI on derivatives (0.1)   (0.1) (0.1)
Cash Flow Hedges | Interest rate contracts | Location, Statement of Income, Balance [Axis]: pfg:NetInvestmentIncomeLoss        
Gains (losses) recognized for hedging relationships        
Gain (loss) reclassified from AOCI on derivatives   0.6   1.3
Amounts related to periodic settlements on derivatives (0.2) (0.2) (0.3) (0.3)
Cash Flow Hedges | Foreign exchange contracts | Location, Statement of Income, Balance [Axis]: pfg:NetInvestmentIncomeLoss        
Gains (losses) recognized for hedging relationships        
Amounts related to periodic settlements on derivatives $ 9.0 9.1 17.4 17.6
Cash Flow Hedges | Foreign exchange contracts | Location, Statement of Income, Balance [Axis]: pfg:NetRealizedCapitalGainsLosses        
Gains (losses) recognized for hedging relationships        
Gain (loss) reclassified from AOCI on derivatives   $ 2.7 $ (0.1) $ 2.7
[1] Includes realized and unrealized gains (losses). See Note 3, Investments, for further details.