Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2017		16,005,408
Beginning balance at Dec. 31, 2017	$ (1,716)	$ 2	$ 158,091	$ (155)	$ (159,654)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(8,775)
Ending balance at Mar. 31, 2018	25,627
Beginning balance (in shares) at Dec. 31, 2017		16,005,408
Beginning balance at Dec. 31, 2017	(1,716)	$ 2	158,091	(155)	(159,654)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(17,064)
Ending balance at Jun. 30, 2018	17,889
Beginning balance (in shares) at Dec. 31, 2017		16,005,408
Beginning balance at Dec. 31, 2017	(1,716)	$ 2	158,091	(155)	(159,654)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(25,559)
Ending balance at Sep. 30, 2018	9,777
Beginning balance (in shares) at Dec. 31, 2017		16,005,408
Beginning balance at Dec. 31, 2017	(1,716)	$ 2	158,091	(155)	(159,654)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	$ 2,139		2,139
Exercise of stock options (in shares)	51,327	51,327
Exercise of stock options	$ 60		60
Liability-based awards reclassified to additional paid-in capital	0
Common stock issued during period (in shares)		10,000,000
Common stock issued during period	35,194	$ 1	35,193
Net loss	(29,239)				(29,239)
Ending balance (in shares) at Dec. 31, 2018		26,056,735
Ending balance at Dec. 31, 2018	6,438	$ 3	195,483	(155)	(188,893)
Beginning balance at Mar. 31, 2018	25,627
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(8,289)
Ending balance at Jun. 30, 2018	17,889
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(8,495)
Ending balance at Sep. 30, 2018	9,777
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(3,680)
Ending balance (in shares) at Dec. 31, 2018		26,056,735
Ending balance at Dec. 31, 2018	6,438	$ 3	195,483	(155)	(188,893)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(6,637)
Ending balance at Mar. 31, 2019	(735)
Beginning balance (in shares) at Dec. 31, 2018		26,056,735
Beginning balance at Dec. 31, 2018	6,438	$ 3	195,483	(155)	(188,893)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(14,933)
Ending balance at Jun. 30, 2019	(8,786)
Beginning balance (in shares) at Dec. 31, 2018		26,056,735
Beginning balance at Dec. 31, 2018	6,438	$ 3	195,483	(155)	(188,893)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(24,429)
Ending balance at Sep. 30, 2019	(17,335)
Beginning balance (in shares) at Dec. 31, 2018		26,056,735
Beginning balance at Dec. 31, 2018	6,438	$ 3	195,483	(155)	(188,893)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	$ 1,188		1,188
Exercise of stock options (in shares)	32,443	32,443
Exercise of stock options	$ 69		69
Liability-based awards reclassified to additional paid-in capital	366		366
Common stock issued during period (in shares)		645,622
Common stock issued during period	747	$ 0	747
Net loss	(30,377)				(30,377)
Ending balance (in shares) at Dec. 31, 2019		26,734,800
Ending balance at Dec. 31, 2019	(22,283)	$ 3	197,853	(155)	(219,984)
Beginning balance at Mar. 31, 2019	(735)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(8,296)
Ending balance at Jun. 30, 2019	(8,786)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(9,496)
Ending balance at Sep. 30, 2019	(17,335)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(5,948)
Ending balance (in shares) at Dec. 31, 2019		26,734,800
Ending balance at Dec. 31, 2019	$ (22,283)	$ 3	$ 197,853	$ (155)	$ (219,984)