Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Deficit
Beginning balance, shares (in shares) at Dec. 31, 2016		15,939,992
Beginning balance at Dec. 31, 2016	$ 31,066	$ 2	$ 154,252	$ (155)	$ (123,033)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	$ 3,758		3,758
Exercise of stock options (in shares)	65,416	65,416
Exercise of stock options	$ 81		81
Net loss	(36,621)				(36,621)
Ending balance, in shares (in shares) at Dec. 31, 2017		16,005,408
Ending 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
Common stock issued through public offering, net of underwriting discounts, warrants, commissions and offering costs (Note 1) (in shares)		10,000,000
Common stock issued through public offering, net of underwriting discounts, warrants, commissions and offering costs (Note 1)	17,388	$ 1	17,387
Net loss	(12,673)				(12,673)
Ending balance, in shares (in shares) at Dec. 31, 2018		26,056,735
Ending balance at Dec. 31, 2018	$ 5,198	$ 3	$ 177,677	$ (155)	$ (172,327)