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STOCK BASED COMPENSATION - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands |  |  | 12 Months Ended
--- | --- | --- | ---
Apr. 26, 2017 | Feb. 13, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
STOCK BASED COMPENSATION |  |  |  |  |
Stock options granted (in shares) |  |  | 338,000 | 645,000 |
Exercise price of options granted (in dollars per share) |  |  | $ 2.99 | $ 3.99 |
Exercisable period of options |  |  | 2 years 2 months 12 days |  |
Number of common stock reserved for issuance |  |  | 17,500,000 |  |
Number of shares of common stock reserved for issuance |  |  | 5,283,137 | 5,294,563 |
Common stock issued |  |  | 337,051,000 | 299,570,000 |
Shares |  |  |  |  |
Balance at the beginning of the period (in shares) |  |  | 4,720,000 | 6,954,000 |
Granted (in shares) |  |  | 338,000 | 645,000 |
Exercised (in shares) |  |  | (94,000) | (1,457,000) |
Forfeited (in shares) |  |  | (37,000) | (1,422,000) |
Expired (in shares) |  |  | (21,000) |  |
Balance at the end of the period (in shares) |  |  | 4,906,000 | 4,720,000 | 6,954,000
Exercisable at the end of the period (in shares) |  |  | 3,438,000 |  |
Weighted Average Exercise Price |  |  |  |  |
Balance at the beginning of the period (in dollars per share) |  |  | $ 2.41 | $ 2.49 |
Granted (in dollars per share) |  |  | 2.99 | 3.99 |
Exercised (in dollars per share) |  |  | $ 1.30 | $ 2.48 |
Proceeds from exercise of stock options |  |  | $ 121 | $ 3,730 |
Forfeited (in dollars per share) |  |  | $ 4.28 | $ 3.45 |
Expired (in dollars per share) |  |  | 5.00 |  |
Balance at the end of the period (in dollars per share) |  |  | 2.45 | $ 2.41 | $ 2.49
Exercisable (in dollars per share) |  |  | $ 2.48 |  |
Weighted Average Remaining Contractual Life |  |  |  |  |
Outstanding at the end of the period |  |  | 2 years 7 months 6 days | 3 years 4 months 24 days | 4 years 1 month 6 days
Exercisable period of options |  |  | 2 years 2 months 12 days |  |
Intrinsic Value |  |  |  |  |
Outstanding at the beginning of the period (in dollars) |  |  | $ 4,388 | $ 98 |
Exercised (in dollars) |  |  | 87 | 1,601 |
Outstanding at the end of the period (in dollars) |  |  | 2,564 | $ 4,388 | $ 98
Exercisable at the end of the period (in dollars) |  |  | $ 1,686 |  |
Granted (in shares) |  |  | 338,000 | 645,000 |
Equity Incentive Plan |  |  |  |  |
STOCK BASED COMPENSATION |  |  |  |  |
Common stock issued |  |  | 94,000 | 1,494,085 |
Weighted Average Exercise Price |  |  |  |  |
Exercised (in dollars per share) |  |  | $ 1.30 | $ 2.51 |
Proceeds from exercise of stock options |  |  | $ 100 | $ 3,700 |
Maximum |  |  |  |  |
STOCK BASED COMPENSATION |  |  |  |  |
Maximum number of shares that may be subject to grants of options to an individual in a calendar year |  |  | 1,000,000 |  |
Lexam |  |  |  |  |
STOCK BASED COMPENSATION |  |  |  |  |
Share replacement awards | $ 100 |  |  |  |
Common Stock Exchange Ratio For Acquisition |  | 0.056% |  |  |
Certain employees and directors |  |  |  |  |
STOCK BASED COMPENSATION |  |  |  |  |
Stock options granted (in shares) |  |  | 300,000 | 600,000 | 2,700,000
Exercise price of options granted (in dollars per share) |  |  | $ 2.99 | $ 3.99 | $ 1.03
Shares |  |  |  |  |
Granted (in shares) |  |  | 300,000 | 600,000 | 2,700,000
Weighted Average Exercise Price |  |  |  |  |
Granted (in dollars per share) |  |  | $ 2.99 | $ 3.99 | $ 1.03
Intrinsic Value |  |  |  |  |
Granted (in shares) |  |  | 300,000 | 600,000 | 2,700,000
Vesting period of options |  |  | 3 years |  |
Exercise period of options |  |  | 5 years |  |

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