Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Balance at beginning of period (shares) at Dec. 31, 2018		27,806,934
Balance at beginning of period at Dec. 31, 2018	$ 143,275	$ 3	$ 243,337	$ (99,649)	$ (416)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for employee stock option exercises for cash (shares)		41,740
Issuance of common stock for employee stock option exercises for cash	44		44
Restricted Shares Award (RSA) issuances and forfeitures for terminations, net (shares)		352,417
Restricted Shares Award (RSA) issuances and forfeitures for terminations, net	977		977
Restricted Stock Units (RSU) issuances and forfeitures for terminations, net	165		165
Foreign currency translation adjustment	(10)				(10)
Net loss	(13,117)			(13,117)
Balance at end of period (shares) at Mar. 31, 2019		28,201,091
Balance at end of period at Mar. 31, 2019	131,334	$ 3	244,523	(112,766)	(426)
Balance at beginning of period (shares) at Dec. 31, 2018		27,806,934
Balance at beginning of period at Dec. 31, 2018	143,275	$ 3	243,337	(99,649)	(416)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	(53)
Net loss	(32,178)
Balance at end of period (shares) at Jun. 30, 2019		28,480,743
Balance at end of period at Jun. 30, 2019	114,413	$ 3	246,706	(131,827)	(469)
Balance at beginning of period (shares) at Mar. 31, 2019		28,201,091
Balance at beginning of period at Mar. 31, 2019	131,334	$ 3	244,523	(112,766)	(426)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for employee stock option exercises for cash (shares)		136,164
Issuance of common stock for employee stock option exercises for cash	308		308
Restricted Shares Award (RSA) issuances and forfeitures for terminations, net (shares)		112,417
Restricted Shares Award (RSA) issuances and forfeitures for terminations, net	1,629		1,629
Restricted Stock Units (RSU) issuances and forfeitures for terminations, net	246		246
Issuance of common stock for warrant exercise (shares)		31,071
Foreign currency translation adjustment	(43)				(43)
Net loss	(19,061)			(19,061)
Balance at end of period (shares) at Jun. 30, 2019		28,480,743
Balance at end of period at Jun. 30, 2019	$ 114,413	$ 3	246,706	(131,827)	(469)
Balance at beginning of period (shares) at Dec. 31, 2019	34,110,995	34,110,995
Balance at beginning of period at Dec. 31, 2019	$ 183,003	$ 3	363,012	(179,584)	(428)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for employee stock option exercises for cash (shares)		181,456
Issuance of common stock for employee stock option exercises for cash	344		344
Restricted Shares Award (RSA) issuances and forfeitures for terminations, net (shares)		171,875
Restricted Shares Award (RSA) issuances and forfeitures for terminations, net	3,039		3,039
Restricted Stock Units (RSU) issuances and forfeitures for terminations, net (shares)		46,336
Restricted Stock Units (RSU) issuances and forfeitures for terminations, net	883		883
Foreign currency translation adjustment	(177)				(177)
Net loss	(14,616)			(14,616)
Balance at end of period (shares) at Mar. 31, 2020		34,510,662
Balance at end of period at Mar. 31, 2020	$ 172,476	$ 3	367,278	(194,200)	(605)
Balance at beginning of period (shares) at Dec. 31, 2019	34,110,995	34,110,995
Balance at beginning of period at Dec. 31, 2019	$ 183,003	$ 3	363,012	(179,584)	(428)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	(285)
Net loss	$ (34,399)
Balance at end of period (shares) at Jun. 30, 2020	39,462,405	39,462,405
Balance at end of period at Jun. 30, 2020	$ 297,896	$ 4	512,588	(213,983)	(713)
Balance at beginning of period (shares) at Mar. 31, 2020		34,510,662
Balance at beginning of period at Mar. 31, 2020	172,476	$ 3	367,278	(194,200)	(605)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for employee stock option exercises for cash (shares)		319,680
Issuance of common stock for employee stock option exercises for cash	1,008		1,008
Restricted Shares Award (RSA) issuances and forfeitures for terminations, net (shares)		32,063
Restricted Shares Award (RSA) issuances and forfeitures for terminations, net	2,969		2,969
Restricted Stock Units (RSU) issuances and forfeitures for terminations, net	847		847
Follow-on offering - issuance, less closing costs (shares)		4,600,000
Follow-on offering - issuance, less closing costs	140,487	$ 1	140,486
Foreign currency translation adjustment	(108)				(108)
Net loss	$ (19,783)			(19,783)
Balance at end of period (shares) at Jun. 30, 2020	39,462,405	39,462,405
Balance at end of period at Jun. 30, 2020	$ 297,896	$ 4	$ 512,588	$ (213,983)	$ (713)