CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings
Balances at Dec. 31, 2017	$ 405,765	$ 271	$ 125,715	$ 279,779
Net loss	(22,272)			(22,272)
Stock granted under restricted stock plan, net		3	(3)
Stock based compensation	903		903
Shares surrendered by employees to pay taxes	(421)			(421)
Balances at Mar. 31, 2018	383,975	274	126,615	257,086
Balances at Dec. 31, 2017	405,765	271	125,715	279,779
Net loss	(53,821)
Balances at Sep. 30, 2018	357,193	277	131,378	225,538
Balances at Mar. 31, 2018	383,975	274	126,615	257,086
Net loss	(14,812)			(14,812)
Shares sold under ATM program	2,849	3	2,846
Stock granted under restricted stock plan, net	320		320
Stock based compensation	820		820
Other	1			1
Balances at Jun. 30, 2018	373,153	277	130,601	242,275
Net loss	(16,736)			(16,736)
Stock based compensation	777		777
Other	(1)			(1)
Balances at Sep. 30, 2018	357,193	277	131,378	225,538
Balances at Dec. 31, 2018	336,283	277	132,080	203,926
Net loss	(19,994)			(19,994)
Shares sold under ATM program	3,375	9	3,366
Stock granted under restricted stock plan, net		4	(4)
Stock based compensation	710		710
Shares surrendered by employees to pay taxes	(278)			(278)
Balances at Mar. 31, 2019	320,096	290	136,152	183,654
Balances at Dec. 31, 2018	336,283	277	132,080	203,926
Net loss	(65,627)
Balances at Sep. 30, 2019	277,251	294	138,936	138,021
Balances at Mar. 31, 2019	320,096	290	136,152	183,654
Net loss	(16,205)			(16,205)
Shares sold under ATM program	1,231	4	1,227
Modification of warrant	178		178
Stock granted under restricted stock plan, net	79		79
Stock based compensation	652		652
Balances at Jun. 30, 2019	306,031	294	138,288	167,449
Net loss	(29,428)			(29,428)
Stock based compensation	648		648
Balances at Sep. 30, 2019	$ 277,251	$ 294	$ 138,936	$ 138,021