Reinsurance (Schedule of Trust Assets and Reinsurance Liabilities) (Details) - USD ($) $ in Millions |
Jun. 30, 2025 |
Dec. 31, 2024 |
Jun. 30, 2024 |
Dec. 31, 2023 |
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|---|---|---|---|---|---|---|
| Reinsurance [Line Items] | ||||||
| Restricted cash and cash equivalents | $ 493.8 | $ 501.3 | $ 509.3 | $ 457.7 | ||
| Debt Securities, Available-for-sale, Restricted | 107.1 | 106.4 | ||||
| Trust Assets [Member] | ||||||
| Reinsurance [Line Items] | ||||||
| Restricted cash and cash equivalents | 0.8 | 0.3 | ||||
| Debt Securities, Available-for-sale, Restricted | 107.1 | 106.4 | ||||
| Unearned Premium [Member] | ||||||
| Reinsurance [Line Items] | ||||||
| Accounts payable and accrued liabilities | 77.6 | 75.9 | ||||
| Claims Reserve [Member] | ||||||
| Reinsurance [Line Items] | ||||||
| Accounts payable and accrued liabilities | [1] | $ 6.3 | $ 6.0 | |||
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