Reserve for Losses and Loss Adjustment Expenses (Narrative) (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | |
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Dec. 31, 2025 |
|
| Liability for Claims and Claims Adjustment Expense [Line Items] | |||
| Minimum period for claims resolution (in years) | 5 years | ||
| (Favorable) unfavorable development of reserves established in prior years, net | $ (4,906) | $ (892) | $ (90,314) |
| Prior year claims and claims adjustment expense, purchase accounting amortization | 700 | ||
| Specialty P&C | |||
| Liability for Claims and Claims Adjustment Expense [Line Items] | |||
| Net favorable prior year reserve development | 3,600 | ||
| (Favorable) unfavorable development of reserves established in prior years, net | 3,000 | ||
| Segregated Portfolio Cell Reinsurance | Accident Year 2022 and 2024 | |||
| Liability for Claims and Claims Adjustment Expense [Line Items] | |||
| Net favorable prior year reserve development | $ 1,300 | ||