INVESTMENTS - Narrative (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
Dec. 31, 2024 |
|
| Investments, Debt and Equity Securities [Abstract] | |||||
| Net realized gains / (losses) related to sales of investments | $ (32.4) | $ 12.8 | $ 120.6 | $ (160.0) | |
| Net change in unrealized gains / (losses) related to investments | 227.8 | $ (114.3) | (58.4) | $ 121.5 | |
| Debt securities, available-for-sale, accumulated gross unrealized gain (loss), before tax | $ 567.7 | $ 567.7 | $ 627.1 | ||