CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' (DEFICIT) EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Initial Public Offering	Private Placement	Series Seed Convertible Preferred Stock	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series B-1 Convertible Preferred Stock	Series C 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 Deficit	Accumulated Other Comprehensive Income (Loss)
Temporary Equity, Beginning Balance at Dec. 31, 2018				$ 5,900	$ 28,794	$ 38,735
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2018				3,000,000	14,498,547	9,605,905
Beginning Balance at Dec. 31, 2018	$ (34,436)											$ 774			$ (35,210)
Beginning Balance, Shares at Dec. 31, 2018									1,479,188
Vesting of Series A Preferred Stock in connection with collaboration arrangement (Note 5)					$ 332
Vesting of Series A Preferred Stock in connection with collaboration arrangement (Note 5), Shares					166,183
Issuance of Preferred Stock, net of issuance costs							$ 14,024
Issuance of Preferred Stock, net of issuance costs, Shares							3,059,695
Exercise of Stock Options	46											46
Exercise of Stock Options, Shares									77,616
Vesting Restricted Stock, Shares									307,882
Stock-based compensation expense	899											899
Net Loss	(29,733)														(29,733)
Temporary Equity, Ending Balance at Sep. 30, 2019				$ 5,900	$ 29,126	$ 38,735	$ 14,024
Temporary Equity, Ending Balance, Shares at Sep. 30, 2019				3,000,000	14,664,730	9,605,905	3,059,695
Ending Balance at Sep. 30, 2019	(63,224)											1,719			(64,943)
Ending Balance, Shares at Sep. 30, 2019									1,864,686
Temporary Equity, Beginning Balance at Jun. 30, 2019				$ 5,900	$ 29,016	$ 38,735	$ 14,024
Temporary Equity, Beginning Balance, Shares at Jun. 30, 2019				3,000,000	14,609,335	9,605,905	3,059,695
Beginning Balance at Jun. 30, 2019	(52,081)											1,442			(53,523)
Beginning Balance, Shares at Jun. 30, 2019									1,697,293
Vesting of Series A Preferred Stock in connection with collaboration arrangement (Note 5)					$ 110
Vesting of Series A Preferred Stock in connection with collaboration arrangement (Note 5), Shares					55,395
Exercise of Stock Options	43											43
Exercise of Stock Options, Shares									75,565
Vesting Restricted Stock, Shares									91,828
Stock-based compensation expense	234											234
Net Loss	(11,420)														(11,420)
Temporary Equity, Ending Balance at Sep. 30, 2019				$ 5,900	$ 29,126	$ 38,735	$ 14,024
Temporary Equity, Ending Balance, Shares at Sep. 30, 2019				3,000,000	14,664,730	9,605,905	3,059,695
Ending Balance at Sep. 30, 2019	(63,224)											1,719			(64,943)
Ending Balance, Shares at Sep. 30, 2019									1,864,686
Temporary Equity, Beginning Balance at Dec. 31, 2019				$ 5,900	$ 29,237	$ 59,918	$ 14,025
Temporary Equity, Beginning Balance, Shares at Dec. 31, 2019				3,000,000	14,720,126	14,827,580	3,059,695
Beginning Balance at Dec. 31, 2019	(74,406)											2,044			(76,456)	$ 6
Beginning Balance, Shares at Dec. 31, 2019									1,929,516
Vesting of Series A Preferred Stock in connection with collaboration arrangement (Note 5)					$ 222
Vesting of Series A Preferred Stock in connection with collaboration arrangement (Note 5), Shares					110,788
Issuance of Preferred Stock, net of issuance costs						$ 4,800		$ 88,180
Issuance of Preferred Stock, net of issuance costs, Shares						1,182,265		13,539,141
Temporary Equity, Exchange of Series A Convertible Preferred Stock for Series C Preferred Convertible Preferred Stock					$ (3,950)			$ 13,000
Temporary Equity, Exchange of Series A Convertible Preferred Stock for Series C Preferred Convertible Preferred Stock, Shares					(1,988,802)			1,988,802
Exercise of Stock Options	138											138
Exercise of Stock Options, Shares									67,623
Vesting Restricted Stock	110											110
Vesting Restricted Stock, Shares									161,187
Stock-based compensation expense	3,363											3,363
Unrealized gain (loss) on marketable securities	(170)															(170)
Issuance of shares		$ 182,748	$ 13,527							$ 1			$ 182,747	$ 13,527
Issuance of shares, Shares										9,987,520	676,354
Conversion of convertible preferred stock into common stock	211,332								$ 3			211,329
Temporary equity, conversion of convertible preferred stock into common, Shares				(3,000,000)	(12,842,112)	(16,009,845)	(3,059,695)	(15,527,943)
Temporary equity, conversion of convertible preferred stock into common				$ (5,900)	$ (25,509)	$ (64,718)	$ (14,025)	$ (101,180)
Conversion of convertible preferred stock into common, Shares									31,625,534
Net Loss	(32,908)														(32,908)
Temporary Equity, Ending Balance, Shares at Sep. 30, 2020				0	0	0	0
Ending Balance at Sep. 30, 2020	294,685								$ 4			410,925			(116,080)	(164)
Ending Balance, Shares at Sep. 30, 2020									44,447,734
Exchange of Series A Convertible Preferred Stock for Series C Preferred Convertible Preferred Stock	(9,049)											(2,333)			(6,716)
Temporary Equity, Beginning Balance at Jun. 30, 2020				$ 5,900	$ 25,509	$ 64,718	$ 14,025	$ 101,180
Temporary Equity, Beginning Balance, Shares at Jun. 30, 2020				3,000,000	12,842,112	16,009,845	3,059,695	15,527,943
Beginning Balance at Jun. 30, 2020	(107,289)											774			(108,094)	31
Beginning Balance, Shares at Jun. 30, 2020									2,035,956
Exercise of Stock Options	110											110
Exercise of Stock Options, Shares									51,518
Vesting Restricted Stock	111											111
Vesting Restricted Stock, Shares									70,852
Stock-based compensation expense	2,328											2,328
Unrealized gain (loss) on marketable securities	(195)															(195)
Issuance of shares		$ 182,747	$ 13,527							$ 1			$ 182,746	$ 13,527
Issuance of shares, Shares										9,987,520	676,354
Conversion of convertible preferred stock into common stock	211,332								$ 3			211,329
Temporary equity, conversion of convertible preferred stock into common, Shares				(3,000,000)	(12,842,112)	(16,009,845)	(3,059,695)	(15,527,943)
Temporary equity, conversion of convertible preferred stock into common				$ (5,900)	$ (25,509)	$ (64,718)	$ (14,025)	$ (101,180)
Conversion of convertible preferred stock into common, Shares									31,625,534
Net Loss	(7,986)														(7,986)
Temporary Equity, Ending Balance, Shares at Sep. 30, 2020				0	0	0	0
Ending Balance at Sep. 30, 2020	$ 294,685								$ 4			$ 410,925			$ (116,080)	$ (164)
Ending Balance, Shares at Sep. 30, 2020									44,447,734