CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings (accumulated deficit)
Balances at Dec. 31, 2017	$ 405,765	$ 271	$ 125,715	$ 279,779
Net loss	(75,433)			(75,433)
Stock sold under ATM program	2,849	3	2,846
Stock granted under restricted stock plan, net	320	4	316
Stock based compensation	3,203		3,203
Shares surrendered by employees to pay taxes	(421)	(1)		(420)
Balances at Dec. 31, 2018	336,283	277	132,080	203,926
Net loss	(304,201)			(304,201)
Stock sold under ATM program	4,606	13	4,593
Stock granted under restricted stock plan, net	79	4	75
Modification of warrant	178		178
Stock based compensation	2,640		2,640
Shares surrendered by employees to pay taxes	(278)			(278)
Balances at Dec. 31, 2019	$ 39,307	$ 294	$ 139,566	$ (100,553)