Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]	Total
Balance at Dec. 31, 2016	$ 0	$ 169,496	$ 1,235	$ (168,974)	$ 1,757
Balance (in shares) at Dec. 31, 2016	2,801
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ 0	0	0	(13,382)	(13,382)
Foreign currency translation adjustment	0	0	(8)	0	(8)
Stock-based compensation, net	$ 0	499	0	0	499
Stock-based compensation, net (in shares)	17
Issuance of common stock, net	$ 0	5,399	0	0	5,399
Issuance of common stock, net (in shares)	42,017
Issuance of preferred stock, net	$ 0	21,973	0	0	21,973
Conversion of preferred stock into common stock	$ 0	0	0	0	0
Conversion of preferred stock into common stock (in shares)	226,522
Balance at Dec. 31, 2017	$ 0	197,367	1,227	(182,356)	16,238
Balance (in shares) at Dec. 31, 2017	271,357
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ 0	0	0	(17,032)	(17,032)
Foreign currency translation adjustment	0		(4)		(4)
Stock-based compensation, net	$ 0	2,087	0	0	2,087
Stock-based compensation, net (in shares)	12
Issuance of unregistered shares	$ 0	0	0	0	0
Issuance of unregistered shares (in shares)	7,116
Issuance of common stock, net	$ 0	4,647	0	0	4,647
Issuance of common stock, net (in shares)	181,941
Conversion of preferred stock into common stock	$ 0	0	0	0	0
Conversion of preferred stock into common stock (in shares)	53,019
Balance at Dec. 31, 2018	$ 0	$ 204,101	$ 1,223	$ (199,388)	$ 5,936
Balance (in shares) at Dec. 31, 2018	513,445