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]
Exercise of stock options (in shares)			215,464
Exercise of stock options	432			432
Stock-based compensation	2,509			2,509
Net loss	(20,855)				(20,855)
Vesting of shares subject to repurchase from early exercised options	176			176
Ending balance (in shares) at Jun. 30, 2020		50,462,272	3,288,531
Ending balance at Jun. 30, 2020	66,045	$ 224,769	$ 0	12,431	(171,155)
Beginning balance (in shares) at Mar. 31, 2020		50,462,272	3,081,647
Beginning balance at Mar. 31, 2020	76,680	$ 224,769	$ 0	10,636	(158,725)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)			206,884
Exercise of stock options	411			411
Stock-based compensation	1,296			1,296
Net loss	(12,430)				(12,430)
Vesting of shares subject to repurchase from early exercised options	88			88
Ending balance (in shares) at Jun. 30, 2020		50,462,272	3,288,531
Ending balance at Jun. 30, 2020	66,045	$ 224,769	$ 0	12,431	(171,155)
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)			2,422,740
Exercise of stock options	8,347		$ 1	8,346
Vesting of restricted stock units (in shares)			19,191
Employee stock purchase plan (in shares)			115,360
Employee stock purchase plan	2,157			2,157
Stock-based compensation	10,143			10,143
Net loss	(33,589)				(33,589)
Ending balance (in shares) at Jun. 30, 2021		0	67,043,537
Ending balance at Jun. 30, 2021	231,839	$ 0	$ 4	457,308	(225,473)
Beginning balance (in shares) at Mar. 31, 2021		0	66,384,736
Beginning balance at Mar. 31, 2021	242,366	$ 0	$ 4	449,681	(207,319)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)			644,610
Exercise of stock options	1,985			1,985
Vesting of restricted stock units (in shares)			14,191
Stock-based compensation	5,642			5,642
Net loss	(18,154)				(18,154)
Ending balance (in shares) at Jun. 30, 2021		0	67,043,537
Ending balance at Jun. 30, 2021	$ 231,839	$ 0	$ 4	$ 457,308	$ (225,473)