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SHAREHOLDERS' EQUITY - Non-vested Options Outstanding and Exercisable (Details) - $ / shares | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares |  |  |
Stock options granted (in shares) | 5,097,000 | 3,050,000 | 375,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value |  |  |
Stock options granted (in dollars per share) | $ 1.22 | $ 1.73 | $ 1.90
Amended and Restated Equity Incentive Plan and Non-related Plan Options |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares |  |  |
Balance at the beginning of the period (in shares) | 3,034 |  |
Stock options granted (in shares) | 5,097 |  |
Stock options cancelled/forfeited (in shares) | (1,172) |  |
Stock options vested (in shares) | (866) |  |
Balance at the end of the period (in shares) | 6,093 | 3,034 |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value |  |  |
Balance at the beginning of the period (in dollars per share) | $ 0.64 |  |
Stock options granted (in dollars per share) | 0.40 |  |
Stock options cancelled/forfeited (in dollars per share) | 0.60 |  |
Stock options vested (in dollars per share) | 0.71 |  |
Balance at the end of the period (in dollars per share) | $ 0.44 | $ 0.64 |

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- Definition Gross number of share options (or share units) granted during the period. + References No definition available. + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Number of non-vested options outstanding. + References No definition available. + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Number of non-vested options forfeited. + References No definition available. + Details
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- Definition Weighted average grant-date fair value of non-vested options forfeited. + References No definition available. + Details
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- Definition Weighted average grant-date fair value of non-vested options outstanding. + References No definition available. + Details
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- Definition Number of options vested. + References No definition available. + Details
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- Definition Weighted average grant-date fair value of options vested. + References No definition available. + Details
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