INVESTMENTS - Narrative (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Investments, Debt and Equity Securities [Abstract] | ||||
| Net realized gains / (losses) related to sales of investments | $ 13.8 | $ (32.4) | $ 39.9 | $ 120.6 |
| Net change in unrealized gains / (losses) related to investments | $ (128.4) | $ 227.8 | $ (367.0) | $ (58.4) |