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SHAREHOLDERS' EQUITY (Details) $ / shares in Units, $ in Thousands |  |  |  |  |  |  |  | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | ---
Aug. 29, 2016 $ / shares | Aug. 22, 2016 shares | May 31, 2016 item | Feb. 12, 2016 $ / shares | Oct. 01, 2015 USD ($) shares | Aug. 17, 2015 $ / shares | Jun. 18, 2015 $ / shares | Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares | Dec. 31, 2014 USD ($) shares
Common stock issued |  |  |  |  |  |  |  | 299,570,000 | 274,421,000 |
Shares of common stock issued upon exercise of stock options |  |  |  |  |  |  |  | 1,457,000 |  |
Weighted average exercise price of stock options (in dollars per share) | $ / shares |  |  |  |  |  |  |  | $ 2.51 | $ 1.29 |
Proceeds from exercise of stock options | $ |  |  |  |  |  |  |  | $ 3,730 |  | $ 2,292
Exercise of stock options | $ |  |  |  |  |  |  |  | $ 3,730 |  | 1,932
Semi-annual return of capital payable (in dollars per share) | $ / shares |  |  |  |  |  |  |  | 0.005 | 0.010 |
Return of capital distribution paid | $ |  |  |  |  |  |  |  | $ 2,986 | $ 1,503 |
Period of time over which common stock can be repurchased |  |  |  |  | 12 months |  |  |  |  |
Share repurchase program (in shares) |  |  |  |  |  |  |  |  | 1,896,442 |
Share repurchase program | $ |  |  |  |  |  |  |  | $ 582 | $ 1,769 |
Former number of stock listings maintained | item |  |  | 2 |  |  |  |  |  |  |
Number Of Common Stock Shares Per Exchangeable Share |  | 1 |  |  |  |  |  |  |  |
Exchangeable shares converted into common stock |  |  |  |  |  |  |  | 24,200,000 | 4,300,000 |
Exchangeable, shares outstanding |  |  |  |  |  |  |  | 0 | 24,213,000 |
Shares issued for settlement of accounts payable | $ |  |  |  |  |  |  |  |  | $ 443 | 1,004
Exploration costs | $ |  |  |  |  |  |  |  | $ 7,959 | $ 8,798 | $ 11,332
Maximum |  |  |  |  |  |  |  |  |  |
Number of shares authorized to be repurchased |  |  |  |  | 15,000,000 |  |  |  |  |
Authorized maximum to be spent on repurchases | $ |  |  |  |  | $ 15,000 |  |  |  |  |
Equity Incentive Plan |  |  |  |  |  |  |  |  |  |
Common stock issued |  |  |  |  |  |  |  | 1,494,085 |  |
Common Stock |  |  |  |  |  |  |  |  |  |
Shares of common stock issued upon exercise of stock options |  |  |  |  |  |  |  | 1,494 | 0 | 1,499
Exercise of stock options | $ |  |  |  |  |  |  |  | $ 3,730 |  | $ 1,932
Annual return of capital declared (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 0.01 |  |  |
Semi-annual return of capital payable (in dollars per share) | $ / shares | 0.005 |  |  | 0.005 |  | 0.005 |  |  |  |
Share repurchase program (in shares) |  |  |  |  |  |  |  | 558 | 1,896 |
Share repurchase program | $ |  |  |  |  |  |  |  | $ 582 | $ 1,769 |
Shares issued for settlement of accounts payable (in shares) |  |  |  |  |  |  |  |  | 430 | 394
Shares issued to terminate back-in right (in shares) |  |  |  |  |  |  |  |  |  | 850

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