Reserve for Loss and Loss Adjustment Expenses - Narrative (Details) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2022 |
Mar. 31, 2021 |
|
| Segment Reporting Information [Line Items] | ||
| Net adverse prior year development (net favorable prior year reserve development) | $ (7,285) | $ (5,554) |
| Change in deferred gain on retroactive reinsurance | 1,339 | 9,845 |
| AmTrust Quota Share Reinsurance Segment | ||
| Segment Reporting Information [Line Items] | ||
| Deferred gain on retroactive reinsurance decrease | 1,000 | |
| Diversified Reinsurance | ||
| Segment Reporting Information [Line Items] | ||
| Net adverse prior year development (net favorable prior year reserve development) | (2,211) | 14 |
| AmTrust Reinsurance | ||
| Segment Reporting Information [Line Items] | ||
| Net adverse prior year development (net favorable prior year reserve development) | $ (5,074) | $ (5,568) |