Consolidated Statements of Stockholders' Equity (Deficit) (unaudited) - 6 months ended Jun. 30, 2017 - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at December 31, 2016 at Dec. 31, 2016	$ 42,352	$ 27	$ 132,246	$ (89,618)	$ (303)
Balance at December 31, 2016, shares at Dec. 31, 2016		27,150,674
Stock-based compensation	2,069		2,069
Issuance of common stock in follow-on offering, net	9,870	$ 1	9,869
Issuance of common stock in follow-on offering, net, shares		553,825
Exercise of stock options	$ 1,115		1,115
Exercise of stock options, shares	202,008	202,008
Issuance of shares under employee stock purchase plan	$ 854		854
Issuance of shares under employee stock purchase plan, shares		83,790
Other comprehensive income	126				126
Net loss	(9,639)			(9,639)
Balance at June 30, 2017 at Jun. 30, 2017	$ 46,747	$ 28	$ 146,153	$ (99,257)	$ (177)
Balance at March 31, 2017, shares at Jun. 30, 2017		27,990,297