Liability for Future Policy Holder Benefits - Changes in Deferred Profit Liability (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Deferred Profit Liability [Roll Forward] | |||
| Balance, beginning of period | $ 412.1 | $ 337.8 | $ 253.6 |
| Annual assumption changes | 6.3 | 4.8 | 15.0 |
| Profits deferred | 156.6 | 160.7 | 163.1 |
| Interest accrual | 20.2 | 17.1 | 13.2 |
| Amortization | (115.9) | (110.7) | (111.2) |
| Effect of actual variances from expected experience and other changes | 2.4 | 2.4 | 4.1 |
| Balance, end of period | $ 481.7 | $ 412.1 | $ 337.8 |