Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2019		50,462,272	3,073,067
Beginning balance at Dec. 31, 2019	$ 83,783	$ 224,769	$ 0	$ 9,314	$ (150,300)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of convertible preferred stock into common stock (in shares)		(50,462,272)	50,462,272
Conversion of convertible preferred stock into common stock	0	$ (224,769)	$ 3	224,766
Issuance of common stock upon initial public offering, net of issuance costs (in shares)			9,315,000
Issuance of common stock upon initial public offering, net of issuance costs	187,935			187,935
Cashless exercise of common stock warrants (in shares)			123,192
Shares issued in connection with:
Exercise of stock options (in shares)			1,385,220
Exercise of stock options	3,105			3,105
Vesting of shares subject to repurchase from early exercised options	263			263
Stock-based compensation	4,953			4,953
Net loss	(29,456)				(29,456)
Ending balance (in shares) at Sep. 30, 2020		0	64,358,751
Ending balance at Sep. 30, 2020	250,583	$ 0	$ 3	430,336	(179,756)
Beginning balance (in shares) at Jun. 30, 2020		50,462,272	3,288,531
Beginning balance at Jun. 30, 2020	66,045	$ 224,769	$ 0	12,431	(171,155)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of convertible preferred stock into common stock (in shares)		(50,462,272)	50,462,272
Conversion of convertible preferred stock into common stock	0	$ (224,769)	$ 3	224,766
Issuance of common stock upon initial public offering, net of issuance costs (in shares)			9,315,000
Issuance of common stock upon initial public offering, net of issuance costs	187,935			187,935
Cashless exercise of common stock warrants (in shares)			123,192
Shares issued in connection with:
Exercise of stock options (in shares)			1,169,756
Exercise of stock options	2,672			2,672
Vesting of shares subject to repurchase from early exercised options	88			88
Stock-based compensation	2,444			2,444
Net loss	(8,601)				(8,601)
Ending balance (in shares) at Sep. 30, 2020		0	64,358,751
Ending balance at Sep. 30, 2020	250,583	$ 0	$ 3	430,336	(179,756)
Beginning balance (in shares) at Dec. 31, 2020		0	64,486,246
Beginning balance at Dec. 31, 2020	244,781	$ 0	$ 3	436,662	(191,884)
Shares issued in connection with:
Exercise of stock options (in shares)			2,767,866
Exercise of stock options	9,674		$ 1	9,673
Vesting of restricted stock units (in shares)			39,119
Employee stock purchase plan (in shares)			163,008
Employee stock purchase plan	3,644			3,644
Stock-based compensation	16,078			16,078
Net loss	(53,992)				(53,992)
Ending balance (in shares) at Sep. 30, 2021		0	67,456,239
Ending balance at Sep. 30, 2021	220,185	$ 0	$ 4	466,057	(245,876)
Beginning balance (in shares) at Jun. 30, 2021		0	67,043,537
Beginning balance at Jun. 30, 2021	231,839	$ 0	$ 4	457,308	(225,473)
Shares issued in connection with:
Exercise of stock options (in shares)			345,126
Exercise of stock options	1,327			1,327
Vesting of restricted stock units (in shares)			19,928
Employee stock purchase plan (in shares)			47,648
Employee stock purchase plan	1,487			1,487
Stock-based compensation	5,935			5,935
Net loss	(20,403)				(20,403)
Ending balance (in shares) at Sep. 30, 2021		0	67,456,239
Ending balance at Sep. 30, 2021	$ 220,185	$ 0	$ 4	$ 466,057	$ (245,876)