Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total		Initial Public Offering	Private Placement	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock	Series C Redeemable Convertible Preferred Stock	Common Stock	Common Stock Initial Public Offering	Common Stock Private Placement	Additional Paid-In Capital	Additional Paid-In Capital Initial Public Offering	Additional Paid-In Capital Private Placement	Accumulated Other Comprehensive Gain (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2018	$ (71,469)							$ 1							$ (71,470)
Beginning balance, shares at Dec. 31, 2018					56,000,000	49,501,221
Beginning balance at Dec. 31, 2018					$ 61,516	$ 70,587
Beginning balance, shares at Dec. 31, 2018								1,363,000
Issuance of Series C redeemable preferred stock, shares							26,360,745
Issuance of Series C redeemable preferred stock							$ 47,947
Vesting of founders’ common stock and restricted stock awards	28										$ 28
Vesting of founders’ common stock and restricted stock awards, shares								440,964
Option exercises	174										174
Option exercises, shares								42,060
Accretion to redemption value and cumulative dividends on redeemable convertible preferred stock					$ 952	$ 5,273
Accretion to redemption value and cumulative dividends on redeemable convertible preferred stock	(6,225)										(2,031)				(4,194)
Stock-based compensation expense	1,829										1,829
Net unrealized loss on short-term investments	(1)	[1]												$ (1)
Net loss	(631)														(631)
Ending balance at Dec. 31, 2019	$ (76,295)							$ 1						(1)	(76,295)
Ending balance, shares at Dec. 31, 2019					56,000,000	49,501,221	26,360,745
Ending balance at Dec. 31, 2019					$ 62,468	$ 75,860	$ 47,947
Ending balance, shares at Dec. 31, 2019	1,846,024							1,846,024
Issuance of common/preferred stock			$ 148,278	$ 10,000					$ 1			$ 148,277	$ 10,000
Issuance of Series C redeemable preferred stock, shares							28,527,313
Issuance of Series C redeemable preferred stock							$ 52,019
Issuance of common/preferred stock, shares									10,350,000	625,000
Conversion of Series A, B, C convertible preferred stock to common stock	$ 238,294							$ 1			238,293
Conversion of Series A, B, C convertible preferred stock to common stock, shares					(56,000,000)	(49,501,221)	(54,888,058)
Conversion of Series A, B, C convertible preferred stock to common stock					$ (62,468)	$ (75,860)	$ (99,966)
Conversion of Series A, B, C convertible preferred stock to common stock, shares								22,432,029
Vesting of restricted stock awards	11										11
Vesting of restricted stock awards, shares								163,544
Option exercises	442										442
Option exercises, shares								136,198
Stock-based compensation expense	3,895										3,895
Net unrealized loss on short-term investments	(31)	[1]												(31)
Net loss	(41,533)														(41,533)
Ending balance at Dec. 31, 2020	$ 283,061							$ 3			$ 400,918			$ (32)	$ (117,828)
Ending balance, shares at Dec. 31, 2020					0	0	0
Ending balance at Dec. 31, 2020					$ 0	$ 0	$ 0
Ending balance, shares at Dec. 31, 2020	35,552,795							35,552,795

[1] Tax effect is nil for all periods presented.