Investments - Schedule of Allowance for Expected Credit Losses (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 at beginning of period | $ 2.8 | $ 1.9 | $ 0.6 | $ 5.9 |
| Expected credit losses on securities where credit losses were not previously recognized | 1.7 | 0.2 | 3.9 | 0.7 |
| Reductions for expected credit losses on securities where credit losses were previously recognized | (0.3) | (0.8) | (0.2) | (5.2) |
| Securities sold/redeemed/matured | (0.6) | (0.7) | (0.7) | (0.8) |
| Balance at end of period | $ 3.6 | $ 0.6 | $ 3.6 | $ 0.6 |