CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Stockholders' equity, beginning balance (in shares) at Dec. 31, 2018		24,450,757
Stockholders' equity, beginning balance at Dec. 31, 2018	$ 90,192	$ 3	$ 246,927	$ 439	$ (157,177)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options, net of shares withheld (in shares)	444,924	444,788
Issuance of common stock upon exercise of stock options, net of shares withheld	$ 1,490		1,490
Issuance of common stock related to employee stock purchase plan (in shares)	168,457	168,457
Issuance of common stock related to employee stock purchase plan	$ 2,203		2,203
Issuance of common stock upon vesting of restricted stock units (in shares)		108,631
Issuance of common stock upon vesting of restricted stock units	0
Repurchase of unvested early exercised stock options (in shares)		(8,830)
Repurchase of unvested early exercised stock options	0
Stock-based compensation	7,464		7,464
Vesting of early exercised stock options	197		197
Additional accrual of IPO related costs	(160)		(160)
Foreign currency translation	(19)			(19)
Net unrealized gain (loss) on marketable securities	44			44
Net loss	(38,403)				(38,403)
Stockholders' equity, ending balance (in shares) at Dec. 31, 2019		25,163,803
Stockholders' equity, ending balance at Dec. 31, 2019	63,008	$ 3	258,121	464	(195,580)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock from public offerings, net of underwriting discounts, commissions and offering costs (in shares)		6,613,560
Issuance of common stock from public offerings, net of underwriting discounts, commissions and offering costs	$ 134,616	$ 0	134,616
Issuance of common stock upon exercise of stock options, net of shares withheld (in shares)	323,701	323,701
Issuance of common stock upon exercise of stock options, net of shares withheld	$ 1,463		1,463
Issuance of common stock related to employee stock purchase plan (in shares)	137,377	137,377
Issuance of common stock related to employee stock purchase plan	$ 1,915		1,915
Issuance of common stock upon vesting of restricted stock units (in shares)		344,779
Issuance of common stock upon vesting of restricted stock units	0
Stock-based compensation	11,927		11,927
Vesting of early exercised stock options	71		71
Foreign currency translation	119			119
Net unrealized gain (loss) on marketable securities	(59)			(59)
Net loss	(43,697)				(43,697)
Stockholders' equity, ending balance (in shares) at Dec. 31, 2020		32,583,220
Stockholders' equity, ending balance at Dec. 31, 2020	$ 169,363	$ 3	$ 408,113	$ 524	$ (239,277)