Statements of Stockholders' Equity - USD ($) $ in Thousands	Preferred Stock [Member] Series A Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2017	22,000	441,868
Balance at Dec. 31, 2017	$ 21,523		$ 202,972	$ (189,741)	$ (14)	$ 34,740
Issuance of common stock upon ESPP purchase (in shares)		1,859
Issuance of common stock upon ESPP purchase			132			132
Issuance of common stock, net of issuance costs (in shares)		37,364
Issuance of common stock, net of issuance costs			2,852			2,852
Stock-based compensation expense			3,429			3,429
Other comprehensive gain/(loss)					19	19
Net loss				(20,729)		(20,729)
Balance (in shares) at Dec. 31, 2018	22,000	481,091
Balance at Dec. 31, 2018	$ 21,523		209,385	(210,470)	5	20,443
Stock-based compensation expense			943			943
Other comprehensive gain/(loss)					(2)	(2)
Net loss				(14,992)		(14,992)
Conversion of Series A convertible preferred stock into Common Stock (in shares)	(3,046)
Conversion of Series A convertible preferred stock into Common Stock	$ (3,060)
Conversion of Series A convertible preferred stock into Common Stock (in shares)		76,540
Conversion of Series A convertible preferred stock into Common Stock			3,060
Balance (in shares) at Dec. 31, 2019	18,954	557,631
Balance at Dec. 31, 2019	$ 18,463		$ 213,388	$ (225,462)	$ 3	$ 6,392