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