Condensed Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred Shares	Common Shares	Treasury Shares	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2018	$ 152,330	$ 21,850	$ 246,663	$ (10,413)	$ 1,282,762	$ (1,388,532)
Balance (in shares) at Dec. 31, 2018		289,317,460	329,110,863	(3,260,850)
Exercise of stock options	$ 15,456		$ 2,496		12,960
Exercise of stock options (in shares)	3,838,739		3,838,739
Vesting of restricted stock units	$ (9,080)		$ 929	$ (9,080)	(929)
Vesting of restricted stock units (in shares)			1,416,124	(526,708)
Stock-based compensation	6,596				6,596
Loss for the period	(24,431)					(24,431)
Balance at Mar. 31, 2019	140,871	$ 21,850	$ 250,088	$ (19,493)	1,301,389	(1,412,963)
Balance (in shares) at Mar. 31, 2019		289,317,460	334,365,726	(3,787,558)
Balance at Dec. 31, 2019	608,263	$ 21,850	$ 269,173	$ (35,900)	1,764,317	(1,411,177)
Balance (in shares) at Dec. 31, 2019		289,317,460	365,014,893	(4,910,992)
Exercise of stock options	$ 1,306		$ 269		1,037
Exercise of stock options (in shares)	412,465		412,465
Vesting of restricted stock units	$ (13,831)		$ 1,274	$ (13,831)	(1,274)
Vesting of restricted stock units (in shares)			1,951,448	(759,832)
Stock-based compensation	10,591				10,591
Loss for the period	(20,553)					(20,553)
Balance at Mar. 31, 2020	$ 585,776	$ 21,850	$ 270,716	$ (49,731)	$ 1,774,671	$ (1,431,730)
Balance (in shares) at Mar. 31, 2020		289,317,460	367,378,806	(5,670,824)