STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Unaudited) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning Balance at Dec. 31, 2019		$ 178,058
Beginning Balance (in shares) at Dec. 31, 2019		19,278,606
Beginning Balance at Dec. 31, 2019	$ (90,084)			$ 2,606	$ (92,690)
Beginning Balance (in shares) at Dec. 31, 2019			1,984,222
Exercise of common stock options	12			12
Exercise of common stock options (in shares)			13,433
Stock-based compensation expense	527			527
Net loss	(8,872)				(8,872)
Ending Balance at Mar. 31, 2020		$ 178,058
Ending Balance (in shares) at Mar. 31, 2020		19,278,606
Ending Balance at Mar. 31, 2020	(98,417)			3,145	(101,562)
Ending Balance (in shares) at Mar. 31, 2020			1,997,655
Beginning Balance at Dec. 31, 2020	$ 289,776		$ 4	456,196	(166,393)	$ (31)
Beginning Balance (in shares) at Dec. 31, 2020	36,672,415		36,672,415
Exercise of common stock options	$ 16			16
Exercise of common stock options (in shares)	18,411		18,411
Stock-based compensation expense	$ 2,744			2,744
Net loss	(16,461)				(16,509)	48
Ending Balance at Mar. 31, 2021	$ 276,075		$ 4	$ 458,956	$ (182,902)	$ 17
Ending Balance (in shares) at Mar. 31, 2021	36,690,826		36,690,826