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SHAREHOLDERS' EQUITY - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
STOCK BASED COMPENSATION |  |  |  |
Stock options granted (in shares) | 5,097,000 | 3,050,000 | 375,000 |
Exercise price of options granted (in dollars per share) | $ 1.22 | $ 1.73 | $ 1.90 |
Exercisable period of options | 2 years 7 months 6 days |  |  |
Number of common stock reserved for issuance | 17,500,000 |  |  |
Number of shares of common stock reserved for issuance | 2,308,550 | 4,221,023 |  |
Common stock issued | 416,587,000 | 400,339,000 |  |
Maximum number of shares that may be subject to grants of options to an individual in a calendar year | 1,000,000 |  |  |
Shares |  |  |  |
Balance at the beginning of the period (in shares) | 5,269,000 | 4,243,000 | 4,906,000 |
Granted (in shares) | 5,097,000 | 3,050,000 | 375,000 |
Exercised (in shares) | (135,000) | (535,000) | (171,000) |
Forfeited (in shares) | (1,968,000) | (700,000) | (405,000) |
Expired (in shares) | (1,251,000) | (789,000) | (462,000) |
Balance at the end of the period (in shares) | 7,012,000 | 5,269,000 | 4,243,000 | 4,906,000
Exercisable at the end of the period (in shares) | 919,000 |  |  |
Weighted Average Exercise Price |  |  |  |
Balance at the beginning of the period (in dollars per share) | $ 2.00 | $ 2.33 | $ 2.45 |
Granted (in dollars per share) | 1.22 | 1.73 | 1.90 |
Exercised (in dollars per share) | $ 1.02 | $ 1.01 | $ 1.02 |
Proceeds from exercise of stock options | $ 138 | $ 544 | $ 192 |
Forfeited (in dollars per share) | $ 2.18 | $ 2.56 | $ 3.99 |
Expired (in dollars per share) | 1.19 | 2.90 | 2.27 |
Balance at the end of the period (in dollars per share) | 1.55 | $ 2.00 | $ 2.33 | $ 2.45
Exercisable (in dollars per share) | $ 3.02 |  |  |
Weighted Average Remaining Contractual Life |  |  |  |
Outstanding at the end of the period | 4 years 2 months 12 days | 3 years | 2 years | 2 years 7 months 6 days
Exercisable period of options | 2 years 7 months 6 days |  |  |
Intrinsic Value |  |  |  |
Outstanding at the beginning of the period (in dollars) | $ 364 | $ 1,475 | $ 2,564 |
Exercised (in dollars) | 10 | 419 | 195 |
Forfeited (in dollars) | 2 |  |  |
Outstanding at the end of the period (in dollars) | $ 53 | $ 364 | $ 1,475 | $ 2,564
Granted (in shares) | 5,097,000 | 3,050,000 | 375,000 |
Equity Incentive Plan |  |  |  |
STOCK BASED COMPENSATION |  |  |  |
Common stock issued | 135,000 | 535,000 |  |
Weighted Average Exercise Price |  |  |  |
Exercised (in dollars per share) | $ 1.02 | $ 1.02 |  |
Proceeds from exercise of stock options | $ 100 | $ 500 |  |
Employees and Directors |  |  |  |
STOCK BASED COMPENSATION |  |  |  |
Stock options granted (in shares) | 5,100,000 | 3,100,000 | 400,000 |
Exercise price of options granted (in dollars per share) | $ 1.22 | $ 1.73 | $ 1.90 |
Shares |  |  |  |
Granted (in shares) | 5,100,000 | 3,100,000 | 400,000 |
Weighted Average Exercise Price |  |  |  |
Granted (in dollars per share) | $ 1.22 | $ 1.73 | $ 1.90 |
Intrinsic Value |  |  |  |
Granted (in shares) | 5,100,000 | 3,100,000 | 400,000 |
Vesting period of options | 3 years |  |  |
Exercise period of options | 5 years |  |  |
Common Stock and Additional Paid-in Capital |  |  |  |
Shares |  |  |  |
Exercised (in shares) | (135,000) | (535,000) | (182,000) |

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