CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY(Unaudited) - USD ($) $ in Thousands	Total	Common Stock and Additional Paid-In-Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Total stockholders' equity, beginning balance at Dec. 31, 2017	$ 118,942	$ 323,503	$ (204,525)	$ (36)
Issuance of common stock		2,015
Stock-based compensation		2,065
Net loss	(14,442)		(14,442)
Other comprehensive income (loss)	(20)			(20)
Ending balance at Mar. 31, 2018	108,560	327,583	(218,967)	(56)
Total stockholders' equity, beginning balance at Dec. 31, 2018	97,883	337,648	(239,756)	(9)
Issuance of common stock		1,863
Stock-based compensation		3,477
Net loss	(7,068)		(7,068)
Other comprehensive income (loss)	16			16
Ending balance at Mar. 31, 2019	$ 96,171	$ 342,988	$ (246,824)	$ 7