v3.26.1
Stockholders' Equity - Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Other Comprehensive Income (Loss)        
Other comprehensive income (loss), pre-tax $ 347.7 $ 79.9 $ 158.6 $ 613.2
Other comprehensive income (loss), tax (70.3) (2.9) (42.2) (104.1)
Other comprehensive income (loss) 277.4 77.0 116.4 509.1
Net unrealized gains (losses) on available-for-sale securities including NCI        
Other Comprehensive Income (Loss)        
Other comprehensive income (loss) before reclassifications, pre-tax 186.5 273.5 (611.7) 940.3
Adjustments for assumed changes in amortization patterns, pre-tax (0.2) (0.1) 0.4 (0.5)
Adjustments for assumed changes in policyholder liabilities, pre-tax (2.2) (2.6) 9.9 15.7
Other comprehensive income (loss), pre-tax 239.7 315.3 (494.0) 1,062.5
Other comprehensive income (loss) before reclassifications, tax (32.4) (57.6) 136.4 (198.5)
Reclassification from accumulated other comprehensive income, tax (11.8) (9.5) (22.8) (22.6)
Adjustments for assumed changes in amortization patterns, tax 0.1 0.1   0.2
Adjustments for assumed changes in policyholder liabilities, tax 0.4 0.6 (2.1) (3.3)
Other comprehensive income (loss), tax (43.7) (66.4) 111.5 (224.2)
Other comprehensive income (loss) before reclassifications, after-tax 154.1 215.9 (475.3) 741.8
Reclassification from accumulated other comprehensive income, after-tax 43.8 35.0 84.6 84.4
Adjustments for assumed changes in amortization patterns, after-tax (0.1)   0.4 (0.3)
Adjustments for assumed changes in policyholder liabilities, after-tax (1.8) (2.0) 7.8 12.4
Other comprehensive income (loss) 196.0 248.9 (382.5) 838.3
Net unrealized gains (losses) on available-for-sale securities including NCI | Location, Statement of Income, Balance [Axis]: pfg:NetRealizedCapitalGainsLosses        
Other Comprehensive Income (Loss)        
Reclassification from accumulated other comprehensive income, pre-tax 55.6 44.5 107.4 107.0
Net unrealized gains (losses) on derivative instruments including NCI        
Other Comprehensive Income (Loss)        
Other comprehensive income (loss) before reclassifications, pre-tax (27.7) (208.0) 41.2 (189.5)
Reclassification from accumulated other comprehensive income, pre-tax 0.1 (0.6) 0.2 (1.2)
Adjustments for assumed changes in amortization patterns, pre-tax 0.1 0.1 0.1 0.1
Other comprehensive income (loss), pre-tax (27.5) (208.5) 41.5 (190.6)
Other comprehensive income (loss) before reclassifications, tax 5.8 43.6 (8.7) 39.7
Reclassification from accumulated other comprehensive income, tax   0.2   0.3
Adjustments for assumed changes in amortization patterns, tax (0.1)   (0.1)  
Other comprehensive income (loss), tax 5.7 43.8 (8.8) 40.0
Other comprehensive income (loss) before reclassifications, after-tax (21.9) (164.4) 32.5 (149.8)
Reclassification from accumulated other comprehensive income, after-tax 0.1 (0.4) 0.2 (0.9)
Adjustments for assumed changes in amortization patterns, after-tax   0.1   0.1
Other comprehensive income (loss) (21.8) (164.7) 32.7 (150.6)
Liability for future policy benefits discount rate remeasurement gain (loss)        
Other Comprehensive Income (Loss)        
Other comprehensive income (loss), pre-tax 102.2 (107.2) 595.1 (419.6)
Other comprehensive income (loss), tax (31.4) 24.7 (134.6) 87.3
Other comprehensive income (loss) 70.8 (82.5) 460.5 (332.3)
Market risk benefit nonperformance risk remeasurement gain(loss)        
Other Comprehensive Income (Loss)        
Other comprehensive income (loss), pre-tax (2.5) (0.5) 0.8 2.2
Other comprehensive income (loss), tax 0.5 0.1 (0.2) (0.5)
Other comprehensive income (loss) (2.0) (0.4) 0.6 1.7
Foreign currency translation adjustment including NCI        
Other Comprehensive Income (Loss)        
Other comprehensive income (loss) before reclassifications, pre-tax 28.7   8.8  
Reclassification from accumulated other comprehensive income, pre-tax 1.8   1.5  
Other comprehensive income (loss), pre-tax 30.5 89.6 10.3 163.7
Other comprehensive income (loss) before reclassifications, tax     (8.8)  
Other comprehensive income (loss), tax   (7.3) (8.8) (8.0)
Other comprehensive income (loss) before reclassifications, after-tax 28.7      
Reclassification from accumulated other comprehensive income, after-tax 1.8   1.5  
Other comprehensive income (loss) 30.5 82.3 1.5 155.7
Unrecognized postretirement benefit obligation including NCI        
Other Comprehensive Income (Loss)        
Other comprehensive income (loss) before reclassifications, pre-tax 3.2 (13.6) (2.0) (13.6)
Other comprehensive income (loss), pre-tax 5.3 (8.8) 4.9 (5.0)
Other comprehensive income (loss) before reclassifications, tax (0.8) 3.5 0.5 3.5
Reclassification from accumulated other comprehensive income, tax (0.6) (1.3) (1.8) (2.2)
Other comprehensive income (loss), tax (1.4) 2.2 (1.3) 1.3
Other comprehensive income (loss) before reclassifications, after-tax 2.4 (10.1) (1.5) (10.1)
Reclassification from accumulated other comprehensive income, after-tax 1.5 3.5 5.1 6.4
Other comprehensive income (loss) 3.9 (6.6) 3.6 (3.7)
Unrecognized postretirement benefit obligation including NCI | Location, Statement of Income, Balance [Axis]: pfg:OperatingExpenses        
Other Comprehensive Income (Loss)        
Reclassification from accumulated other comprehensive income, pre-tax $ 2.1 $ 4.8 $ 6.9 $ 8.6