RESERVE FOR LOSSES AND LOSS EXPENSES - Narrative (Details) - USD ($) $ in Thousands |
6 Months Ended | |
|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
|
| Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] | ||
| Reinsurance recoverable on unpaid losses | $ 1,611,164 | $ 47,452 |
| Net loss and loss expenses | 1,625,845 | 1,494,659 |
| Cavello Bay Reinsurance Limited | ||
| Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] | ||
| Reinsurance recoverable on unpaid losses | 2,000,000 | |
| Catastrophe and Weather-related Events | ||
| Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] | ||
| Net loss and loss expenses | $ 86,000 | $ 67,000 |