Condensed Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Follow On Public Offering	Private Placement	At The Market Offering	Common Stock	Common Stock Follow On Public Offering	Common Stock Private Placement	Common Stock At The Market Offering	Additional Paid-In Capital	Additional Paid-In Capital Follow On Public Offering	Additional Paid-In Capital Private Placement	Additional Paid-In Capital At The Market Offering	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ 100,400				$ 2				$ 192,824				$ 65	$ (92,491)
Beginning balance, shares at Dec. 31, 2019					20,339,461
Issuance of common stock, net of issuance costs		$ 100,664	$ 19,988			$ 1				$ 100,663	$ 19,988
Issuance of common stock, net of issuance costs, shares						7,166,667	1,333,333
Issuance of common stock upon exercise of stock options	1,028								1,028
Issuance of common stock upon exercise of stock options, shares					218,724
Employee stock purchase plan (ESPP) purchase	$ 132								132
Employee stock purchase plan (ESPP) purchase, shares					18,494
Repurchase of early exercised shares, shares	(10,518)				(10,518)
Vesting of early exercised common stock options and restricted stock	$ 44								44
Stock-based compensation	2,563								2,563
Other comprehensive loss	(30)												(30)
Net loss	(29,360)													(29,360)
Ending balance at Sep. 30, 2020	195,429				$ 3				317,242				35	(121,851)
Ending balance, shares at Sep. 30, 2020					29,066,161
Beginning balance at Jun. 30, 2020	172,058				$ 3				288,923				57	(116,925)
Beginning balance, shares at Jun. 30, 2020					27,184,824
Issuance of common stock, net of issuance costs		7,040	$ 19,988							7,040	$ 19,988
Issuance of common stock, net of issuance costs, shares						500,000	1,333,333
Issuance of common stock upon exercise of stock options	297								297
Issuance of common stock upon exercise of stock options, shares					53,353
Repurchase of early exercised shares, shares					(5,349)
Vesting of early exercised common stock options and restricted stock	13								13
Stock-based compensation	981								981
Other comprehensive loss	(22)												(22)
Net loss	(4,926)													(4,926)
Ending balance at Sep. 30, 2020	195,429				$ 3				317,242				35	(121,851)
Ending balance, shares at Sep. 30, 2020					29,066,161
Beginning balance at Dec. 31, 2020	198,274				$ 3				325,250				7	(126,986)
Beginning balance, shares at Dec. 31, 2020					29,537,216
Issuance of common stock, net of issuance costs		85,990		$ 57,286		$ 1				85,989		$ 57,286
Issuance of common stock, net of issuance costs, shares						5,333,333		3,407,872
Issuance of common stock upon exercise of stock options	1,163								1,163
Issuance of common stock upon exercise of stock options, shares					155,920
Employee stock purchase plan (ESPP) purchase	$ 327								327
Employee stock purchase plan (ESPP) purchase, shares					28,745
Repurchase of early exercised shares, shares	0
Vesting of early exercised common stock options and restricted stock	$ 23								23
Stock-based compensation	6,173								6,173
Other comprehensive loss	(57)												(57)
Net loss	(31,550)													(31,550)
Ending balance at Sep. 30, 2021	317,629				$ 4				476,211				(50)	(158,536)
Ending balance, shares at Sep. 30, 2021					38,463,086
Beginning balance at Jun. 30, 2021	240,260				$ 3				387,215				(4)	(146,954)
Beginning balance, shares at Jun. 30, 2021					33,033,793
Issuance of common stock, net of issuance costs		$ 85,990				$ 1				$ 85,989
Issuance of common stock, net of issuance costs, shares						5,333,333
Issuance of common stock upon exercise of stock options	806								806
Issuance of common stock upon exercise of stock options, shares					95,960
Vesting of early exercised common stock options and restricted stock	3								3
Stock-based compensation	2,198								2,198
Other comprehensive loss	(46)												(46)
Net loss	(11,582)													(11,582)
Ending balance at Sep. 30, 2021	$ 317,629				$ 4				$ 476,211				$ (50)	$ (158,536)
Ending balance, shares at Sep. 30, 2021					38,463,086