CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2019		0	17,130,907
Beginning balance at Dec. 31, 2019	$ 85,113	$ 0	$ 17	$ 137,308	$ (52,212)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation expense	1,577			1,577
Exercise of common stock options (in shares)			32,602
Exercise of common stock options	71			71
Issuance of common stock under the employee stock purchase plan (in shares)			39,987
Issuance of common stock under the employee stock purchase plan	603			603
Net loss	570				570
Ending balance (in shares) at Mar. 31, 2020		0	17,203,496
Ending balance at Mar. 31, 2020	87,934	$ 0	$ 17	139,559	(51,642)
Beginning balance (in shares) at Dec. 31, 2020		0	24,812,487
Beginning balance at Dec. 31, 2020	415,691	$ 0	$ 25	478,162	(62,496)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation expense	$ 4,913			4,913
Exercise of common stock options (in shares)	170,484		171,315
Exercise of common stock options	$ 991			991
Issuance of common stock under the employee stock purchase plan (in shares)			70,711
Issuance of common stock under the employee stock purchase plan	1,233			1,233
Public offering of common stock, adjustment to offering costs	39			39
Net loss	(4,280)				(4,280)
Ending balance (in shares) at Mar. 31, 2021		0	25,054,513
Ending balance at Mar. 31, 2021	$ 418,587	$ 0	$ 25	$ 485,338	$ (66,776)