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, 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		$ 227				227
Sale of shares for cash		$ 29,875				29,875
Sale of shares for cash (in shares)		30,000
Sale of flow-through common stock	$ 10,785				$ 10,785
Sale of flow-through common stock (in shares)	12,601
Net loss			(12,466)			(12,466)
Balance at Mar. 31, 2021		$ 1,589,763	(1,196,014)			393,749
Balance (in shares) at Mar. 31, 2021		459,188
Balance at Dec. 31, 2021		$ 1,615,596	(1,240,432)	$ 14,777		389,941
Balance (in shares) at Dec. 31, 2021		459,188
Increase (Decrease) in Shareholders' Equity
Stock-based compensation		$ 183				183
Sale of flow-through common stock	$ 10,320				$ 10,320
Sale of flow-through common stock (in shares)	14,500
Net loss			(19,327)	(1,737)		(21,064)
Balance at Mar. 31, 2022		$ 1,626,099	$ (1,259,759)	$ 13,040		$ 379,380
Balance (in shares) at Mar. 31, 2022		473,688