Debt Securities, Available-for-sale, Allowance for Credit Losses Rollforward (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward] | ||||
| Balance, Beginning Balance | $ 5.9 | |||
| Balance, Ending Balance | $ 0.0 | 0.0 | ||
| All Other Corporate Bonds | ||||
| Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward] | ||||
| Balance, Beginning Balance | 0.0 | $ 3.8 | 5.9 | $ 2.8 |
| Debt Securities, Available-for-sale, Credit losses on securities for which credit losses were not previously recorded | 0.0 | 9.6 | 0.0 | 10.5 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Sell before Recovery | (5.9) | 0.0 | ||
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Change in allowance due to change in intent to hold securities to maturity | 0.0 | 1.0 | 0.0 | 1.1 |
| Balance, Ending Balance | $ 0.0 | $ 14.4 | $ 0.0 | $ 14.4 |