Reinsurance (Schedule of Trust Assets and Reinsurance Liabilities) (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
Mar. 31, 2025 |
Dec. 31, 2024 |
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|---|---|---|---|---|---|---|
| Reinsurance [Line Items] | ||||||
| Restricted cash and cash equivalents | $ 525.7 | $ 477.9 | $ 591.8 | $ 501.3 | ||
| Debt Securities, Available-for-sale, Restricted | 109.4 | 106.2 | ||||
| Trust Assets [Member] | ||||||
| Reinsurance [Line Items] | ||||||
| Restricted cash and cash equivalents | 1.7 | 0.7 | ||||
| Debt Securities, Available-for-sale, Restricted | 109.4 | 106.2 | ||||
| Unearned Premium [Member] | ||||||
| Reinsurance [Line Items] | ||||||
| Accounts payable and accrued liabilities | 78.8 | 74.0 | ||||
| Claims Reserve [Member] | ||||||
| Reinsurance [Line Items] | ||||||
| Accounts payable and accrued liabilities | [1] | $ 5.4 | $ 5.9 | |||
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