Condensed Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Balances at Dec. 31, 2020	$ 41,166	$ 27	$ 299,953	$ (258,814)
Common Stock Balance, Shares at Dec. 31, 2020		26,562,000
Exercise of stock options	475		475
Exercise of stock options, shares		223,000
Stock‑based compensation	1,752		1,752
Net loss	(6,961)			(6,961)
Balances at Mar. 31, 2021	36,432	$ 27	302,180	(265,775)
Common Stock Balance, Shares at Mar. 31, 2021		26,785,000
Balances at Dec. 31, 2021	19,727	$ 31	321,669	(301,973)
Common Stock Balance, Shares at Dec. 31, 2021		30,790,000
Issuance of common stock under employee stock purchase plan	202		202
Issuance of common stock under employee stock purchase plan, Shares		99,000
Issuance of common stock for deferred offering costs	600		600
Issuance of common stock for deferred offering costs, Shares		184,000
Issuance of common stock, net of discounts and commissions	1,417	$ 1	1,416
Issuance of common stock, net of discounts and commissions, Shares		709,000
Exercise of stock options	$ 75		75
Exercise of stock options, shares	107,000	107,000
Stock‑based compensation	$ 1,346		1,346
Net loss	(15,586)			(15,586)
Balances at Mar. 31, 2022	$ 7,781	$ 32	$ 325,308	$ (317,559)
Common Stock Balance, Shares at Mar. 31, 2022		31,889,000