CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock Direct Offering	Common Stock Public Offering	Common Stock	Additional Paid in Capital Direct Offering	Additional Paid in Capital Public Offering	Additional Paid in Capital	Accumulated Deficit	Direct Offering	Public Offering	Total
Balance at beginning of period at Dec. 31, 2019			$ 46			$ 193,308	$ (189,763)			$ 3,591
Balance at beginning of period (in shares) at Dec. 31, 2019			4,580,127
Increase (Decrease) in Stockholders' Equity
Net loss							(16,723)			(16,723)
Reverse stock split adjustment			(826)
Warrants exercises			$ 3			3,054				3,057
Warrants exercises (in shares)			254,760
Sale of common stock	$ 24	$ 22		$ 28,178	$ 26,472			$ 28,202	$ 26,494
Sale of common stock (in shares)	2,428,846	2,211,538
Stock-based compensation			$ 0			1,252				1,252
Stock-based compensation (in shares)			23,332
Balance at end of period at Sep. 30, 2020			$ 95			252,264	(206,486)			45,873
Balance at end of period (in shares) at Sep. 30, 2020			9,497,777
Balance at beginning of period at Jun. 30, 2020			$ 95			251,858	(198,553)			53,400
Balance at beginning of period (in shares) at Jun. 30, 2020			9,497,777
Increase (Decrease) in Stockholders' Equity
Net loss							(7,933)			(7,933)
Stock-based compensation						406				406
Balance at end of period at Sep. 30, 2020			$ 95			252,264	(206,486)			45,873
Balance at end of period (in shares) at Sep. 30, 2020			9,497,777
Balance at beginning of period at Dec. 31, 2020			$ 95			252,645	(214,491)			$ 38,249
Balance at beginning of period (in shares) at Dec. 31, 2020			9,491,111							9,491,111
Increase (Decrease) in Stockholders' Equity
Net loss							(13,484)			$ (13,484)
Stock-based compensation			$ 0			1,026				1,026
Stock-based compensation (in shares)			15,308
Balance at end of period at Sep. 30, 2021			$ 95			253,671	(227,975)			$ 25,791
Balance at end of period (in shares) at Sep. 30, 2021			9,506,419							9,506,419
Balance at beginning of period at Jun. 30, 2021			$ 95			253,343	(223,341)			$ 30,097
Balance at beginning of period (in shares) at Jun. 30, 2021			9,506,419
Increase (Decrease) in Stockholders' Equity
Net loss							(4,634)			(4,634)
Stock-based compensation						328				328
Balance at end of period at Sep. 30, 2021			$ 95			$ 253,671	$ (227,975)			$ 25,791
Balance at end of period (in shares) at Sep. 30, 2021			9,506,419							9,506,419