Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common stock options	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income and (Loss)
Balance (in shares) at Dec. 31, 2018		27,391,000
Beginning Balance at Dec. 31, 2018	$ 22,898	$ 27	$ 115,450	$ (92,564)	$ (15)
Increase (Decrease) in Stockholders' Equity
Vesting of restricted stock units (in shares)		1,317,000
Vesting of restricted stock units	1	$ 1
Stock-based compensation	5,463		5,463
Sales of common stock, net of offering costs (in shares)		3,961,000
Sale of common stock, net of offering costs	9,919	$ 4	9,915
Exercises of warrants (in shares)		487,000
Exercises of warrants	1,387	$ 1	1,386
Net loss	(29,928)			(29,928)
Foreign currency translation adjustment	$ 16				16
Balance (in shares) at Dec. 31, 2019	33,156,246	33,156,000
Ending Balance at Dec. 31, 2019	$ 9,756	$ 33	132,214	(122,492)	1
Increase (Decrease) in Stockholders' Equity
Vesting of restricted stock units (in shares)		2,183,000
Vesting of restricted stock units	2	$ 2
Stock-based compensation	6,166		6,166
Sales of common stock, net of offering costs (in shares)		23,776,000
Sale of common stock, net of offering costs	$ 37,447	$ 24	37,423
Exercises of warrants (in shares)		7,000
Exercises of stock options (in shares)	5,939	6,000
Exercise of stock options	$ 10		10
Net loss	(28,414)			(28,414)
Foreign currency translation adjustment	$ 86				86
Balance (in shares) at Dec. 31, 2020	59,128,356	59,128,000
Ending Balance at Dec. 31, 2020	$ 25,053	$ 59	$ 175,813	$ (150,906)	$ 87