Markel Fronting Arrangement - Narrative (Details) - Hagerty Reinsurance Limited - USD ($) $ in Millions |
9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2026 |
Dec. 31, 2025 |
|
| Markel Fronting Arrangment [Line Items] | ||
| Premium percentage | 100.00% | |
| Ownership interest | 100.00% | |
| Fronting fee percentage | 2.00% | |
| Consideration received, deposit liability | $ 50.5 | |
| Estimated value liability assumed | $ (39.2) | |
| Deposit liability, deferred gain | $ 11.3 |