v3.26.3
Future Policy Benefits and Claims - Benefits and Protection (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Dec. 31, 2025
Present value of expected future policy benefit payments        
Future policy benefits $ 33,503.6   $ 33,503.6 $ 39,993.8
Benefits and Protection        
Present value of expected future policy benefit payments        
Future policy benefits 3,379.8   3,379.8 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 47.6   47.6 163.2
Effect of actual variances from expected experience (29.8)   (29.8) 11.7
Adjusted beginning of period balance at original discount rate 4,608.4   4,608.4 4,572.2
Interest accrual     161.6 208.7
Net premiums collected     (323.3) (418.8)
Issuances     157.2 228.5
Balance at end of period at original discount rate 4,603.9   4,603.9 4,590.6
Effect of changes in discount rate assumptions at end of period (529.5)   (529.5) (198.4)
Balance at end of period, Present value of expected net premiums 4,074.4   4,074.4 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 63.8   63.8 240.4
Effect of actual variances from expected experience (51.1)   (51.1) 4.1
Adjusted beginning of period balance at original discount rate 6,136.3   6,136.3 5,965.7
Interest accrual     217.1 275.3
Benefit payments     (251.2) (359.7)
Issuances     166.5 242.3
Balance at end of period at original discount rate 6,268.7   6,268.7 6,123.6
Effect of changes in discount rate assumptions at end of period (671.0)   (671.0) (215.7)
Balance at end of period, Present value of expected future policy benefit payments 5,597.7   5,597.7 5,907.9
Future policy benefits 1,523.3   1,523.3 1,515.7
Reinsurance impact (4.9)   (4.9) 9.8
Future policy benefits after reinsurance $ 1,518.4   $ 1,518.4 $ 1,525.5
Weighted-average duration for future policy benefits (in years) 7 years   7 years 7 years 4 months 24 days
Increase (decrease) in LFPB from actuarial assumptions $ 16.2 $ 77.2    
Income before taxes, net of reinsurance increase (decrease) from actuarial assumptions (13.2) (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 25.8   25.8 (22.5)
Effect of actual variances from expected experience 104.3   104.3 114.8
Adjusted beginning of period balance at original discount rate 3,220.7   3,220.7 3,209.3
Interest accrual     82.6 108.8
Net premiums collected     (227.6) (298.0)
Issuances     51.2 70.5
Balance at end of period at original discount rate 3,126.9   3,126.9 3,090.6
Effect of changes in discount rate assumptions at end of period (540.1)   (540.1) (349.8)
Balance at end of period, Present value of expected net premiums 2,586.8   2,586.8 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 49.7   49.7 (42.6)
Effect of actual variances from expected experience 111.1   111.1 107.9
Adjusted beginning of period balance at original discount rate 6,087.1   6,087.1 5,877.7
Interest accrual     164.4 213.8
Benefit payments     (182.6) (234.1)
Issuances     49.5 68.9
Balance at end of period at original discount rate 6,118.4   6,118.4 5,926.3
Effect of changes in discount rate assumptions at end of period (1,675.1)   (1,675.1) (1,191.3)
Balance at end of period, Present value of expected future policy benefit payments 4,443.3   4,443.3 4,735.0
Future policy benefits 1,856.5   1,856.5 1,994.2
Reinsurance impact (405.7)   (405.7) (430.0)
Future policy benefits after reinsurance $ 1,450.8   $ 1,450.8 $ 1,564.2
Weighted-average duration for future policy benefits (in years) 16 years 7 months 6 days   16 years 7 months 6 days 17 years 2 months 12 days
Increase (decrease) in LFPB from actuarial assumptions $ 23.9 (20.1)    
Income before taxes, net of reinsurance increase (decrease) from actuarial assumptions $ (13.1) $ 16.2