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STOCKHOLDERS' EQUITY - EQUITY PLANS - SCHEDULE OF AGGREGATE STOCK OPTION AND AWARD ACTIVITY (Parenthetical) (Details) - shares | Feb. 28, 2022 | Dec. 31, 2021 | Dec. 31, 2020
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Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Stock options outstanding (in shares) |  | 49,952,409 | 43,663,691
Common stock, shares reserved for future issuance (in shares) |  | 133,292,810 |
2018 Inducement Award Plan |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Common stock, shares reserved for future issuance (in shares) |  | 15,100,000 |
Performance-Based Stock Options |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Stock options outstanding (in shares) |  | 6,050,000 |
Subsequent Event | 2018 Inducement Award Plan |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Common stock, shares reserved for future issuance (in shares) | 16,100,000 |  |

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