v3.26.1
Stockholders' Equity - AOCI and Noncontrolling Interest (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Change in accumulated other comprehensive income (loss) rollforward        
Balances     $ 11,883.9  
Balances $ 12,142.8   12,142.8  
Change in redeemable noncontrolling interest rollforward        
Redeemable noncontrolling interest, balance at beginning of period 544.1 $ 326.7 474.3 $ 337.7
Net income (loss) attributable to redeemable noncontrolling interest 26.3 25.9 14.2 37.4
Redeemable noncontrolling interest of deconsolidated entities (0.2) (10.4) (7.5) (22.9)
Contributions from redeemable noncontrolling interest 157.3 58.1 283.4 88.9
Distributions to redeemable noncontrolling interest (15.1) (13.3) (46.0) (45.1)
Purchase of subsidiary shares from redeemable noncontrolling interest     (0.9) (1.6)
Stock-based compensation attributable to redeemable noncontrolling interest   0.1   0.1
Other comprehensive income (loss) attributable to redeemable noncontrolling interest (0.7) 4.1 (5.8) (3.3)
Redeemable noncontrolling interest, balance at end of period 711.7 391.2 711.7 391.2
Accumulated other comprehensive income (loss)        
Change in accumulated other comprehensive income (loss) rollforward        
Balances (4,343.7) (4,785.9) (4,188.4) (5,224.8)
Other comprehensive income (loss) during the period, net of adjustments 230.8 34.5 31.3 421.6
Amounts reclassified from AOCI 47.1 38.1 91.3 89.9
Other comprehensive income (loss) 277.9 72.6 122.6 511.5
Balances (4,065.8) (4,713.3) (4,065.8) (4,713.3)
Net unrealized gains (losses) on available-for-sale securities        
Change in accumulated other comprehensive income (loss) rollforward        
Balances (3,807.6) (4,103.5) (3,229.1) (4,692.9)
Other comprehensive income (loss) during the period, net of adjustments 152.2 213.9 (467.1) 753.9
Amounts reclassified from AOCI 43.8 35.0 84.6 84.4
Other comprehensive income (loss) 196.0 248.9 (382.5) 838.3
Balances (3,611.6) (3,854.6) (3,611.6) (3,854.6)
Net unrealized gains (losses) on available-for-sale debt securities with allowance for credit losses (12.1) (4.5) (12.1) (4.5)
Net unrealized gains (losses) on derivative instruments        
Change in accumulated other comprehensive income (loss) rollforward        
Balances 22.6 65.9 (31.9) 51.8
Other comprehensive income (loss) during the period, net of adjustments (21.9) (164.3) 32.5 (149.7)
Amounts reclassified from AOCI 0.1 (0.4) 0.2 (0.9)
Other comprehensive income (loss) (21.8) (164.7) 32.7 (150.6)
Balances 0.8 (98.8) 0.8 (98.8)
Liability for future policy benefits discount rate remeasurement gain (loss)        
Change in accumulated other comprehensive income (loss) rollforward        
Balances 1,202.2 1,188.4 812.5 1,438.2
Other comprehensive income (loss) during the period, net of adjustments 70.8 (82.5) 460.5 (332.3)
Other comprehensive income (loss) 70.8 (82.5) 460.5 (332.3)
Balances 1,273.0 1,105.9 1,273.0 1,105.9
Market risk benefit nonperformance risk remeasurement gain (loss)        
Change in accumulated other comprehensive income (loss) rollforward        
Balances (10.8) (12.9) (13.4) (15.0)
Other comprehensive income (loss) during the period, net of adjustments (2.0) (0.4) 0.6 1.7
Other comprehensive income (loss) (2.0) (0.4) 0.6 1.7
Balances (12.8) (13.3) (12.8) (13.3)
Foreign currency translation adjustment        
Change in accumulated other comprehensive income (loss) rollforward        
Balances (1,569.9) (1,705.7) (1,546.6) (1,785.9)
Other comprehensive income (loss) during the period, net of adjustments 29.3 77.9 6.3 158.1
Amounts reclassified from AOCI 1.7   1.4  
Other comprehensive income (loss) 31.0 77.9 7.7 158.1
Balances (1,538.9) (1,627.8) (1,538.9) (1,627.8)
Unrecognized postretirement benefit obligations        
Change in accumulated other comprehensive income (loss) rollforward        
Balances (180.2) (218.1) (179.9) (221.0)
Other comprehensive income (loss) during the period, net of adjustments 2.4 (10.1) (1.5) (10.1)
Amounts reclassified from AOCI 1.5 3.5 5.1 6.4
Other comprehensive income (loss) 3.9 (6.6) 3.6 (3.7)
Balances $ (176.3) $ (224.7) $ (176.3) $ (224.7)