Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Redeemable Convertible Preferred Stock	Series A Preferred Stock Second Tranche Closing	Series A Preferred Stock	Series B Preferred Stock	Common Stock	Treasury Stock	Additional Paid-In-Capital	Other Comprehensive Loss	Accumulated Deficit	Total
Balance at beginning at Dec. 31, 2017	$ 5,000								$ (4,564)	$ (4,564)
Balance at beginning (in shares) at Dec. 31, 2017	5,000,000				226,400
Repurchase of founders’ stock (in shares)					(75,467)	75,467
Issuance of treasury stock as founders’ stock (in shares)					75,467	(75,467)
Issuance of stock		$ 24,996	$ 8,787	$ 45,271
Issuance of stock (in shares)		25,000,001	17,653,333	13,871,948
Settlement of future purchase obligation	$ 32,750									(32,750)
Issuance of Series A redeemable convertible preferred stock, in settlement of anti dilution right liability			$ 7,404
Issuance of Series A redeemable convertible preferred stock, in settlement of anti dilution right liability, ( in shares)			3,205,128
Extinguishment of call option liability							$ 36,750			36,750
Exercise of stock options							8			$ 8
Exercise of stock options (in shares)					12,586					12,586
Stock-based compensation expense							121			$ 121
Accretion of redeemable convertible preferred stock to redemption value	520						(233)		(287)	(520)
Net loss									(81,714)	(81,714)
Balance at ending at Dec. 31, 2018	$ 124,728						36,646		(86,565)	(49,919)
Balance at ending (in shares) at Dec. 31, 2018	64,730,410				238,986
Conversion of convertible preferred stock into common stock	$ 124,728				$ 2		(124,726)			(124,728)
Conversion of convertible preferred stock into common stock upon closing of public offering (in shares)	(64,730,410)				21,056,136
Issuance of stock					$ 1		95,452			95,453
Issuance of stock (in shares)					6,612,500
Issuance of restricted common stock upon early exercise of stock options (in shares)					491,207
Exercise of stock options							130			$ 130
Exercise of stock options (in shares)					164,503					655,710
Vesting of restricted common stock							240			$ 240
Issuance of common stock pursuant to ESPP purchases							85			85
Issuance of common stock pursuant to ESPP purchases (in shares)					4,505
Stock-based compensation expense							1,770			1,770
Net unrealized loss on marketable securities								$ (6)		(6)
Net loss									(43,755)	(43,755)
Balance at ending at Dec. 31, 2019					$ 3		$ 259,049	$ (6)	$ (130,320)	$ 128,726
Balance at ending (in shares) at Dec. 31, 2019					28,567,837