REDEMPTION SETTLEMENT ASSETS, RESTRICTED - Narratives (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
|
| REDEMPTION SETTLEMENT ASSETS, RESTRICTED. | ||||
| Realized gain (loss) | $ 300,000 | $ (600,000) | $ 1,000,000.0 | |
| Realized gains or losses | $ 0 | $ 0 | $ 200,000 | $ 0 |