CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit	Total
Balance at Dec. 31, 2012	$ 1,349,777	$ (294)	$ (459,892)	$ 889,591
Balance (in shares) at Dec. 31, 2012	296,025,000
Increase (Decrease) in Shareholders' Equity
Stock-based compensation	$ 1,382			1,382
Shares issued for litigation settlement	$ 3,270			3,270
Shares issued for litigation settlement (in shares)	1,000,000
Exercise of stock options	$ 95			$ 95
Exercise of stock options (in shares)	48,000			48,000
Exercise of stock options assumed from Minera Andes Inc. acquisition	$ 76			$ 76
Exercise of stock options assumed from Minera Andes Inc. acquisition (in shares)	45,000
Shares issued for Mexico mining concessions	$ 96			96
Shares issued for Mexico mining concessions (in shares)	41,000
Unrealized loss on marketable securities		(1)		(1)
Unrealized (loss) gain on available-for-sale securities, net of taxes				(1)
Net loss			(147,742)	(147,742)
Balance at Dec. 31, 2013	$ 1,354,696	(295)	(607,634)	746,767
Balance (in shares) at Dec. 31, 2013	297,159,000
Increase (Decrease) in Shareholders' Equity
Shares issued for the settlement of accounts payable	$ 1,004			1,004
Shares issued for settlement of accounts payable (in shares)	394,000
Stock-based compensation	$ 1,324			1,324
Exercise of stock options	$ 1,932			$ 1,932
Exercise of stock options (in shares)	1,499,000			1,499,000
Exercise of stock options assumed from Minera Andes Inc. acquisition	$ 360			$ 360
Exercise of stock options assumed from Minera Andes Inc. acquisition (in shares)	198,000
Shares issued to terminate TNR Gold Corp's back-in right	$ 1,352			1,352
Shares issued to terminate TNR Gold Corp's back-in right (in shares)	850,000
Unrealized (loss) gain on available-for-sale securities, net of taxes		419		419
Net loss			(311,943)	(311,943)
Balance at Dec. 31, 2014	$ 1,360,668	124	(919,577)	441,215
Balance (in shares) at Dec. 31, 2014	300,100,000
Increase (Decrease) in Shareholders' Equity
Shares issued for the settlement of accounts payable	$ 443			443
Shares issued for settlement of accounts payable (in shares)	430,000
Stock-based compensation	$ 1,305			1,305
Share repurchase (note 10)	$ (1,769)			$ (1,769)
Share repurchase (note 10) (in shares)	(1,896,000)			(1,896,442)
Return of capital distribution (note 10)	$ (1,503)			$ (1,503)
Exercise of stock options (in shares)				272,000
Unrealized (loss) gain on available-for-sale securities, net of taxes		(949)		$ (949)
Net loss			(20,450)	(20,450)
Balance at Dec. 31, 2015	$ 1,359,144	$ (825)	$ (940,027)	$ 418,292
Balance (in shares) at Dec. 31, 2015	298,634,000