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FAIR VALUE MEASUREMENTS - EQUITY INVESTMENT (Details) - Equity Investment - USD ($) |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Aug. 03, 2017 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2007
Equity Investments [Line Item] |  |  |  |  |
Number of shares owned |  |  |  |  | 13,842,625
Cost method investments cost basis |  |  |  | $ 0 | $ 0
Trading restriction period | 24 months |  |  |  |
Fair value of equity investment |  | $ 389,000 |  |  |
Increase (decrease) in fair value of equity investment |  | (195,000) | $ (541,000) |  |
Gain (loss) related to foreign currency translation |  | $ (1,000) | $ (63,000) |  |

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