Debt Securities, Available-for-sale, Allowance for Credit Losses Rollforward (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward] | ||
| Balance, Beginning of Period | $ 2.8 | |
| Balance, End of Period | 3.8 | |
| All Other Corporate Bonds | ||
| Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward] | ||
| Balance, Beginning of Period | 2.8 | $ 2.2 |
| Credit losses on securities for which credit losses were not previously recorded | 0.9 | 0.0 |
| Change in allowance on securities with allowance recorded in previous period | 0.1 | 0.0 |
| Balance, End of Period | $ 3.8 | $ 2.2 |