CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock Lexam VG Gold	Common Stock	Warrants	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Lexam VG Gold	Total
Balance at Dec. 31, 2016		$ 1,360,345		$ 1,666	$ (918,972)		$ 443,039
Balance (in shares) at Dec. 31, 2016		299,570
Increase (Decrease) in Shareholders' Equity
Stock-based compensation (note 9)		$ 745					745
Shareholders' distribution (note 8)		(1,498)					(1,498)
Shares issued in connection with the acquisition	$ 38,141					$ 38,141
Shares issued in connection with the acquisition (in shares)	12,687
Exercise of stock options (note 8)		$ 47					47
Exercise of stock options (note 8) (in shares)		20
Other comprehensive income (note 2)				2,799			2,799
Net loss					(4,728)		(4,728)
Balance at Jun. 30, 2017		$ 1,397,780		4,465	(923,700)		478,545
Balance (in shares) at Jun. 30, 2017		312,277
Increase (Decrease) in Shareholders' Equity
Adoption of ASU 2016-01 (note 2) | Accounting Standards Update 2016-01				(3,000)	3,000
Balance at Dec. 31, 2017		$ 1,444,056	$ 3,823	$ 3,000	(929,606)		521,273
Balance (in shares) at Dec. 31, 2017		337,051
Balance at Dec. 31, 2017		$ 1,444,056	3,823		(926,606)		521,273
Increase (Decrease) in Shareholders' Equity
Stock-based compensation (note 9)		396					396
Shareholders' distribution (note 8)		(1,685)					(1,685)
Shares issued in connection with the acquisition		$ 391					391
Shares issued in connection with the acquisition (in shares)		178
Exercise of stock options (note 8)		$ 45					45
Exercise of stock options (note 8) (in shares)		39
Net loss					(10,591)		(10,591)
Balance at Jun. 30, 2018		$ 1,443,203	$ 3,823		$ (937,197)		$ 509,829
Balance (in shares) at Jun. 30, 2018		337,268