Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Share Capital	Additional Paid-in Capital	Deficit
Balance, beginning of period at Dec. 31, 2019		$ 10,270	$ 1,282,627	$ (260,287)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options			0
Stock-based compensation (Note 7)			1,778
Net income (loss)	$ (730,096)			(730,096)
Balance, end of period at Sep. 30, 2020	304,292	10,270	1,284,405	(990,383)
Balance, beginning of period at Jun. 30, 2020		10,270	1,283,798	(882,562)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options			0
Stock-based compensation (Note 7)			607
Net income (loss)	(107,821)			(107,821)
Balance, end of period at Sep. 30, 2020	304,292	10,270	1,284,405	(990,383)
Balance, beginning of period at Dec. 31, 2020		10,270	1,285,018	(1,038,254)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options			18
Stock-based compensation (Note 7)			1,857
Net income (loss)	(20,042)			(20,042)
Balance, end of period at Sep. 30, 2021	238,867	10,270	1,286,893	(1,058,296)
Balance, beginning of period at Jun. 30, 2021		10,270	1,286,235	(1,093,303)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options			10
Stock-based compensation (Note 7)			648
Net income (loss)	35,007			35,007
Balance, end of period at Sep. 30, 2021	$ 238,867	$ 10,270	$ 1,286,893	$ (1,058,296)