CONSOLIDATED STATEMENTS OF CHANGES IN REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Temporary equity, beginning balance (shares) at Dec. 31, 2017	11,871,578
Temporary equity, beginning balance at Dec. 31, 2017	$ 118,548
Increase (Decrease) in Temporary Equity
Conversion from preferred stock to common stock (shares)	(11,871,578)
Conversion from preferred stock to common stock	$ (118,548)
Temporary equity, ending balance (shares) at Dec. 31, 2018	0
Temporary equity, ending balance at Dec. 31, 2018	$ 0
Stockholders' equity (deficit), beginning balance (in shares) at Dec. 31, 2017		3,603,140
Stockholders' equity (deficit), beginning balance at Dec. 31, 2017	$ (129,378)	$ 1	$ 9,943	$ 402	$ (139,724)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options, net of shares withheld (in shares)	395,117	289,077
Issuance of common stock upon exercise of stock options, net of shares withheld	$ 1,136		1,136
Issuance of common stock upon exercise of unvested stock options (in shares)		106,028
Issuance of common stock upon exercise of unvested stock options	0
Conversion from preferred stock to common stock (in shares)		12,066,654
Conversion from preferred stock to common stock	118,548	$ 1	118,547
Conversion from preferred stock warrants to common stock warrants	1,248		1,248
Issuance of common stock from warrants exercise (in shares)		121,486
Issuance of common stock from warrants exercise	0
Issuance of common stock from IPO proceeds, net (in shares)		8,280,000
Issuance of common stock from IPO proceeds, net	113,603	$ 1	113,602
Repurchase of unvested early exercised stock options (in shares)		(15,628)
Repurchase of unvested early exercised stock options	0
Stock-based compensation	2,312		2,312
Vesting of early exercised stock options	139		139
Foreign currency translation	27			27
Unrealized gain on marketable securities	10			10
Net loss	(17,453)				(17,453)
Stockholders' equity (deficit), ending balance (in shares) at Dec. 31, 2018		24,450,757
Stockholders' equity (deficit), ending balance at Dec. 31, 2018	$ 90,192	$ 3	246,927	439	(157,177)
Temporary equity, ending balance (shares) at Dec. 31, 2019	0
Temporary equity, ending balance at Dec. 31, 2019	$ 0
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
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)
Unrealized gain on marketable securities	44			44
Net loss	(38,403)				(38,403)
Stockholders' equity (deficit), ending balance (in shares) at Dec. 31, 2019		25,163,803
Stockholders' equity (deficit), ending balance at Dec. 31, 2019	$ 63,008	$ 3	$ 258,121	$ 464	$ (195,580)