Condensed Statements of Changes in Convertible Preferred Stock and Stockholders' Deficit (unaudited) - USD ($) $ in Thousands	Series A Preferred Stock	Common stock	Additional paid-in capital	Accumulated deficit	Total
Balance at Dec. 31, 2018			$ 908	$ (26,113)	$ (25,205)
Balance (shares) at Dec. 31, 2018		1,087,821
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			11		11
Exercise of stock option (shares)		5,207
Net loss				(7,522)	(7,522)
Balance at Sep. 30, 2019			919	(33,635)	(32,716)
Balance (shares) at Sep. 30, 2019		1,093,028
Balance at Dec. 31, 2018	$ 27,513
Balance (shares) at Dec. 31, 2018	3,108,776
Balance at Sep. 30, 2019	$ 27,513
Balance (shares) at Sep. 30, 2019	3,108,776
Balance at Jun. 30, 2019			918	(30,898)	(29,980)
Balance (shares) at Jun. 30, 2019		1,093,028
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			1		1
Net loss				(2,737)	(2,737)
Balance at Sep. 30, 2019			919	(33,635)	(32,716)
Balance (shares) at Sep. 30, 2019		1,093,028
Balance at Jun. 30, 2019	$ 27,513
Balance (shares) at Jun. 30, 2019	3,108,776
Balance at Sep. 30, 2019	$ 27,513
Balance (shares) at Sep. 30, 2019	3,108,776
Balance at Dec. 31, 2019			927	(36,557)	(35,630)
Balance (shares) at Dec. 31, 2019		1,099,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			302		302
Exercise of stock options			7		7
Exercise of stock option (shares)		25,346
Net loss				(13,764)	(13,764)
Balance at Sep. 30, 2020			1,236	(50,321)	(49,085)
Balance (shares) at Sep. 30, 2020		1,124,616
Balance at Dec. 31, 2019	$ 38,894				38,894
Balance (shares) at Dec. 31, 2019	4,443,259
Increase (Decrease) in Temporary Equity [Roll Forward]
Sale of Series A convertible preferred stock and warrants with a fair value of $1,522, net of $49 of issuance costs	$ 9,475
Sale of Series A convertible preferred stock and warrants with a fair value of $1,522, net of $49 of issuance costs (shares)	1,226,925
Balance at Sep. 30, 2020	$ 48,369				48,369
Balance (shares) at Sep. 30, 2020	5,670,184
Balance at Jun. 30, 2020			1,115	(41,944)	(40,829)
Balance (shares) at Jun. 30, 2020		1,112,393
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			117		117
Exercise of stock options			4		4
Exercise of stock option (shares)		12,223
Net loss				(8,377)	(8,377)
Balance at Sep. 30, 2020			$ 1,236	$ (50,321)	(49,085)
Balance (shares) at Sep. 30, 2020		1,124,616
Balance at Jun. 30, 2020	$ 48,391
Balance (shares) at Jun. 30, 2020	5,670,184
Increase (Decrease) in Temporary Equity [Roll Forward]
Series A convertible preferred stock issuance costs	$ (22)
Balance at Sep. 30, 2020	$ 48,369				$ 48,369
Balance (shares) at Sep. 30, 2020	5,670,184