CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Shares and Additional Paid-in Capital Flow-through common shares	Common Shares and Additional Paid-in Capital	Accumulated Deficit	Noncontrolling Interest	Flow-through common shares	Total
Balance at Dec. 31, 2018		$ 1,457,422	$ (971,476)			$ 485,946
Balance (in shares) at Dec. 31, 2018		344,560
Increase (Decrease) in Shareholders' Equity
Stock-based compensation		$ 694				694
Exercise of stock options		$ 544				$ 544
Exercise of stock options (in shares)		535				535
Units Issued for cash, net of share issue costs		$ 69,467				$ 69,467
Units Issued for cash, net of share issue costs (in shares)		53,880
Stock issued during the period		$ 1,851				1,851
Stock issued during the period (in shares)		1,010
Shares issued for acquisition of mineral property interests		$ 724				724
Shares issued for acquisition of mineral property interests (in shares)		354
Net loss			(59,747)			(59,747)
Balance at Dec. 31, 2019		$ 1,530,702	(1,031,223)			499,479
Balance (in shares) at Dec. 31, 2019		400,339
Increase (Decrease) in Shareholders' Equity
Stock-based compensation		$ 613				613
Exercise of stock options		$ 138				$ 138
Exercise of stock options (in shares)		135				135
Stock issued during the period	$ 15,478				$ 15,478
Stock issued during the period (in shares)	13,968
Shares issued for debt refinancing		$ (1,875)				$ (1,875)
Shares issued for debt refinancing (in shares)		2,092
Shares issued for acquisition of mineral property interests		$ 70				70
Shares issued for acquisition of mineral property interests (in shares)		53
Net loss			(152,325)			(152,325)
Balance at Dec. 31, 2020		$ 1,548,876	(1,183,548)			365,328
Balance (in shares) at Dec. 31, 2020		416,587
Increase (Decrease) in Shareholders' Equity
Stock-based compensation		$ 837				837
Units Issued for cash, net of share issue costs		$ 29,875				29,875
Units Issued for cash, net of share issue costs (in shares)		30,000
Stock issued during the period	$ 10,785				$ 10,785
Stock issued during the period (in shares)	12,601
Issuance of equity by subsidiary (Note 20)		$ 25,223		$ 14,605		39,828
Net loss			(56,884)	172		(56,712)
Balance at Dec. 31, 2021		$ 1,615,596	$ (1,240,432)	$ 14,777		$ 389,941
Balance (in shares) at Dec. 31, 2021		459,188