Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
Beginning Balance at Dec. 31, 2018	$ 1	$ 223,440	$ (207,330)	$ 16,111
Beginning Balance, (in shares) at Dec. 31, 2018	310,330
Share-based compensation expense		268		$ 268
Issuance of common stock upon vesting of restricted stock units (in shares)	143
Issuance of restricted common stock (in shares)	6,886			6,886
Issuance of common stock under ESPP		1		$ 1
Issuance of common stock under ESPP (in shares)	36
Increase in fair value attributable to warrant modifications		666		666
Issuance of common stock and warrants in public offerings	$ 1	366		367
Issuance of common stock and warrants in public offerings (in shares)	233,341
Net loss			(11,830)	(11,830)
Ending Balance at Dec. 31, 2019	$ 2	224,741	(219,160)	$ 5,583
Ending Balance, (in shares) at Dec. 31, 2019	550,736			550,736
Share-based compensation expense		215		$ 215
Issuance of common stock upon vesting of restricted stock units (in shares)	100			584
Fractional shares issued due to reverse stock split	7,692
Forfeiture of restricted stock	(584)
Issuance of common stock upon exercise of warrants		343		$ 343
Issuance of common stock upon exercise of warrants (in shares)	8,618,089
Issuance of common stock and warrants in public offerings	$ 1	22,118		22,119
Issuance of common stock and warrants in public offerings (in shares)	14,455,853
Net loss			(9,074)	(9,074)
Ending Balance at Dec. 31, 2020	$ 3	$ 247,417	$ (228,234)	$ 19,186
Ending Balance, (in shares) at Dec. 31, 2020	23,631,886			23,631,886