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FAIR VALUE MEASUREMENTS - EQUITY INVESTMENT (Details) - USD ($) |  |  | 3 Months Ended |  |
--- | --- | --- | --- | --- | ---
Dec. 01, 2020 | Aug. 03, 2020 | Mar. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2007
Equity Investments [Line Item] |  |  |  |  |
Number of shares owned |  | 35,990,825 | 0 | 688,929 | 13,842,625
Business Combination Cost Of Acquired Entity Equity Interests Issued And Issuable Fair Value Method |  | we received 13 BARD1 shares for every five shares of Sienna ordinary shares, resulting in our ownership of 35,990,825 shares of BARD1. |  |  |
Equity investment reverse stock split | 1 for 30 |  |  |  |
Realized investment gains (losses) |  |  | $ 1,233,000 |  |
Maximum |  |  |  |  |
Equity Investments [Line Item] |  |  |  |  |
Cost method investments ownership percentage |  |  |  |  | 20.00%
Equity Investment |  |  |  |  |
Equity Investments [Line Item] |  |  |  |  |
Cost method investments cost basis |  |  |  |  | $ 0

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