STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Beginning Balance at Dec. 31, 2019	$ 7,610	$ 2	$ 152,024	$ (144,416)
Beginning Balance, shares at Dec. 31, 2019		1,594,070
Share-based compensation	16		16
Net loss	(1,320)			(1,320)
Ending Balance at Mar. 31, 2020	6,306	$ 2	152,040	(145,736)
Ending Balance, shares at Mar. 31, 2020		1,594,070
Beginning Balance at Dec. 31, 2019	7,610	$ 2	152,024	(144,416)
Beginning Balance, shares at Dec. 31, 2019		1,594,070
Ending Balance at Dec. 31, 2020	$ 46,521	$ 10	200,665	(154,154)
Ending Balance, shares at Dec. 31, 2020	9,548,150	9,548,150
Beginning Balance at Mar. 31, 2020	$ 6,306	$ 2	152,040	(145,736)
Beginning Balance, shares at Mar. 31, 2020		1,594,070
Issuance of common stock and exercise of prefunded warrants for cash, net of offering costs	5,297		5,297
Issuance of common stock and exercise of prefunded warrants for cash, net of offering costs, shares		673,500
Share-based compensation	4		4
Net loss	(1,302)			(1,302)
Ending Balance at Jun. 30, 2020	10,305	$ 2	157,341	(147,038)
Ending Balance, shares at Jun. 30, 2020		2,267,570
Issuance of common stock for cash, net of offering costs	42,136	$ 7	42,129
Issuance of common stock for cash, net of offering costs, shares		7,018,054
Share-based compensation	5		5
Net loss	(1,991)			(1,991)
Ending Balance at Sep. 30, 2020	50,455	$ 9	199,475	(149,029)
Ending Balance, shares at Sep. 30, 2020		9,285,624
Issuance of common stock for cash, net of offering costs	1,173	$ 1	1,172
Issuance of common stock for cash, net of offering costs, shares		262,526
Share-based compensation	18		18
Net loss	(5,125)			(5,125)
Ending Balance at Dec. 31, 2020	$ 46,521	$ 10	200,665	(154,154)
Ending Balance, shares at Dec. 31, 2020	9,548,150	9,548,150
Issuance of common stock for cash, net of offering costs	$ 23,347	$ 4	23,343
Issuance of common stock for cash, net of offering costs, shares		4,861,993
Share-based compensation	141		141
Net loss	(4,100)			(4,100)
Ending Balance at Mar. 31, 2021	$ 65,909	$ 14	$ 224,149	$ (158,254)
Ending Balance, shares at Mar. 31, 2021	14,410,143	14,410,143