RESERVE FOR LOSSES AND LOSS EXPENSES - Narrative (Details) - USD ($) $ in Thousands |
6 Months Ended | |
|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] | ||
| Net loss and loss expenses | $ 1,833,311 | $ 1,625,845 |
| 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 | $ 128,000 | $ 86,000 |