SECURITIES AND OTHER INVESTMENTS OWNED AND SECURITIES SOLD NOT YET PURCHASED - Schedule of equity securities without readily determinable fair value (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | 85 Months Ended | ||
|---|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
|
| Securities And Other Investments Owned And Securities Sold Not Yet Purchased [Abstract] | |||||
| Upward carrying value changes | $ 48 | $ 0 | $ 1,463 | $ 1,732 | $ 12,601 |
| Downward carrying value changes/impairment | $ (145) | $ (227) | $ (2,413) | $ (819) | $ (13,698) |