Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	The September 2019 Offering [Member] Common Stock [Member]	The September 2019 Offering [Member] Additional Paid-in Capital [Member]	The September 2019 Offering [Member] Retained Earnings [Member]	The September 2019 Offering [Member]	The October 2020 Offering [Member] Common Stock [Member]	The October 2020 Offering [Member] Additional Paid-in Capital [Member]	The October 2020 Offering [Member] Retained Earnings [Member]	The October 2020 Offering [Member] AOCI Attributable to Parent [Member]	The October 2020 Offering [Member]	Placement Agents' Designees [Member] Common Stock [Member]	Placement Agents' Designees [Member] Additional Paid-in Capital [Member]	Placement Agents' Designees [Member] Retained Earnings [Member]	Placement Agents' Designees [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balances (in shares) at Dec. 31, 2019														48,254,994
Balances at Dec. 31, 2019														$ 5	$ 129,608	$ (116,661)		$ 12,952
Issuance of common stock upon exercise of common stock warrants (in shares)														19,726,120
Issuance of common stock upon exercise of common stock warrants														$ 2	10,347	0		$ 10,349
Issuance of common stock upon exercise of stock options (in shares)														23,606				23,606
Issuance of common stock upon exercise of stock options														$ 0	18	0		$ 18
Stock-based compensation														0	96	0		96
Net loss														$ 0	0	(1,297)		(1,297)
Issuance of common stock, pre-funded warrants and common stock warrants, net of offering costs (in shares)	4,000,000
Issuance of common stock, pre-funded warrants and common stock warrants, net of offering costs	$ 0	$ 8,722	$ 0	$ 8,722
Issuance of common stock warrants to placement agents’ designees										$ 0	$ 453	$ 0	$ 453
Balances (in shares) at Mar. 31, 2020														72,004,720
Balances at Mar. 31, 2020														$ 7	149,244	(117,958)		31,293
Balances (in shares) at Dec. 31, 2020														110,271,093
Balances at Dec. 31, 2020														$ 11	272,274	(148,881)	$ 0	123,404
Issuance of common stock (in shares)					6,654,367
Issuance of common stock					$ 1	$ 65,711	$ 0	$ 0	$ 65,712
Issuance of common stock upon exercise of common stock warrants (in shares)														830,722
Issuance of common stock upon exercise of common stock warrants														$ 0	1,649	0	0	$ 1,649
Issuance of common stock upon exercise of stock options (in shares)														207,730				207,730
Issuance of common stock upon exercise of stock options														$ 0	231	0	0	$ 231
Stock-based compensation														0	1,251	0	0	1,251
Unrealized loss on available-for-sale investments														0	0	0	(5)	(5)
Net loss														$ 0	0	(16,007)	0	(16,007)
Balances (in shares) at Mar. 31, 2021														117,963,912
Balances at Mar. 31, 2021														$ 12	$ 341,116	$ (164,888)	$ (5)	$ 176,235