v3.26.1
Future Policy Benefits and Claims - Benefits and Protection (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended 12 Months Ended
Sep. 30, 2025
Jun. 30, 2026
Dec. 31, 2025
Present value of expected future policy benefit payments      
Future policy benefits   $ 39,320.6 $ 39,993.8
Benefits and Protection      
Present value of expected future policy benefit payments      
Future policy benefits   3,595.1 3,509.9
Benefits and Protection | Life Insurance | Term life      
Present value of expected net premiums      
Balance at beginning of period, Present value of expected net premiums   4,392.2 4,107.2
Effect of changes in discount rate assumptions at beginning of period   198.4 290.1
Balance at beginning of period at original discount rate   4,590.6 4,397.3
Effect of changes in cash flow assumptions     163.2
Effect of actual variances from expected experience   (16.4) 11.7
Adjusted beginning of period balance at original discount rate   4,574.2 4,572.2
Interest accrual   107.3 208.7
Net premiums collected   (213.2) (418.8)
Issuances   109.6 228.5
Balance at end of period at original discount rate   4,577.9 4,590.6
Effect of changes in discount rate assumptions at end of period   (260.1) (198.4)
Balance at end of period, Present value of expected net premiums   4,317.8 4,392.2
Present value of expected future policy benefit payments      
Balance at beginning of period, Present value of expected future policy benefit payments   5,907.9 5,355.2
Effect of changes in discount rate assumptions at beginning of period   215.7 366.0
Balance at beginning of period at original discount rate   6,123.6 5,721.2
Effect of changes in cash flow assumptions     240.4
Effect of actual variances from expected experience   (26.8) 4.1
Adjusted beginning of period balance at original discount rate   6,096.8 5,965.7
Interest accrual   143.7 275.3
Benefit payments   (177.2) (359.7)
Issuances   116.1 242.3
Balance at end of period at original discount rate   6,179.4 6,123.6
Effect of changes in discount rate assumptions at end of period   (305.9) (215.7)
Balance at end of period, Present value of expected future policy benefit payments   5,873.5 5,907.9
Future policy benefits   1,555.7 1,515.7
Reinsurance impact   9.6 9.8
Future policy benefits after reinsurance   $ 1,565.3 $ 1,525.5
Weighted-average duration for future policy benefits (in years)   7 years 1 month 6 days 7 years 4 months 24 days
Increase (decrease) in LFPB from actuarial assumptions $ 77.2    
Income before taxes, net of reinsurance increase (decrease) from actuarial assumptions (63.0)    
Benefits and Protection | Specialty Benefits | Individual disability      
Present value of expected net premiums      
Balance at beginning of period, Present value of expected net premiums   $ 2,740.8 $ 2,680.6
Effect of changes in discount rate assumptions at beginning of period   349.8 436.4
Balance at beginning of period at original discount rate   3,090.6 3,117.0
Effect of changes in cash flow assumptions     (22.5)
Effect of actual variances from expected experience   50.8 114.8
Adjusted beginning of period balance at original discount rate   3,141.4 3,209.3
Interest accrual   54.7 108.8
Net premiums collected   (148.7) (298.0)
Issuances   31.7 70.5
Balance at end of period at original discount rate   3,079.1 3,090.6
Effect of changes in discount rate assumptions at end of period   (384.7) (349.8)
Balance at end of period, Present value of expected net premiums   2,694.4 2,740.8
Present value of expected future policy benefit payments      
Balance at beginning of period, Present value of expected future policy benefit payments   4,735.0 4,509.6
Effect of changes in discount rate assumptions at beginning of period   1,191.3 1,302.8
Balance at beginning of period at original discount rate   5,926.3 5,812.4
Effect of changes in cash flow assumptions     (42.6)
Effect of actual variances from expected experience   48.1 107.9
Adjusted beginning of period balance at original discount rate   5,974.4 5,877.7
Interest accrual   108.7 213.8
Benefit payments   (122.9) (234.1)
Issuances   30.6 68.9
Balance at end of period at original discount rate   5,990.8 5,926.3
Effect of changes in discount rate assumptions at end of period   (1,257.0) (1,191.3)
Balance at end of period, Present value of expected future policy benefit payments   4,733.8 4,735.0
Future policy benefits   2,039.4 1,994.2
Reinsurance impact   (432.1) (430.0)
Future policy benefits after reinsurance   $ 1,607.3 $ 1,564.2
Weighted-average duration for future policy benefits (in years)   16 years 10 months 24 days 17 years 2 months 12 days
Increase (decrease) in LFPB from actuarial assumptions (20.1)    
Income before taxes, net of reinsurance increase (decrease) from actuarial assumptions $ 16.2