Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Preferred Stock Series X redeemable convertible preferred stock	Common stock	Additional Paid-in Capital	Deficit Accumulated during the Development Stage	Accumulated other comprehensive loss	Total
Balance, beginning of period at Dec. 31, 2019	$ 0	$ 2	$ 259,315	$ (223,597)	$ 0
Balance, beginning of period (in shares) at Dec. 31, 2019	0	2,072,266
Increase (Decrease) in Shareholders' Equity
Issuance of common stock in an underwritten public offering, net of issuance costs			24,558
Issuance of common stock for at-the-market offerings			16,268
Issuance of common stock for at-the-market offerings (in shares)		392,288
Issuance of common stock in underwritten public offerings		$ 1
Issuance of common stock and warrants in public offerings (in shares)		881,666
Stock-based compensation expense			1,085
Net loss				(28,322)		$ (28,322)
Balance, end of period at Sep. 30, 2020		$ 3	301,226	(251,919)	0	49,310
Balance, end of period (in shares) at Sep. 30, 2020		3,346,220
Balance, beginning of period at Jun. 30, 2020	$ 0	$ 3	291,912	(241,057)	1
Balance, beginning of period (in shares) at Jun. 30, 2020	0	3,137,264
Increase (Decrease) in Shareholders' Equity
Issuance of common stock for at-the-market offerings			8,939
Issuance of common stock for at-the-market offerings (in shares)		208,956
Stock-based compensation expense			375
Net loss				(10,862)		(10,862)
Realized loss on short-term investments					(1)	(1)
Balance, end of period at Sep. 30, 2020		$ 3	301,226	(251,919)	$ 0	49,310
Balance, end of period (in shares) at Sep. 30, 2020		3,346,220
Balance, beginning of period at Dec. 31, 2020	$ 0	$ 4	301,562	(260,897)		$ 40,669
Balance, beginning of period (in shares) at Dec. 31, 2020	0	3,347,386				3,347,389
Increase (Decrease) in Shareholders' Equity
Reclassification of preferred stock to permanent equity	$ 240,881
Reclassification of preferred stock to permanent equity (in shares)	86,077
Conversion of preferred stock into common stock	$ (168,920)
Conversion of preferred stock into common stock (in shares)	(54,622)
Issuance of preferred stock in a private offering of public equity, net of issuance costs			19,565
Issuance of common stock upon acquisition of Quellis			8,098
Issuance of common stock upon acquisition of Quellis (in shares)		555,444
Issuance of common stock upon the conversion of preferred stock		$ 9	168,912
Issuance of common stock upon the conversion of preferred stock (in shares)		9,103,664
Dividend on convertible preferred stock related to beneficial conversion feature and issuance costs	$ 24,437		(24,437)
Expense related to warrants inherited in acquisition of Quellis			772
Reclassification of warrant liability to additional paid-in capital			3,468
Issuance of common stock upon exercise of options			6
Fractional shares eliminated pursuant to reverse stock split		(9)
Stock-based compensation expense			2,390
Net loss				(185,421)		$ (185,421)
Balance, end of period at Sep. 30, 2021	$ 96,398	$ 13	480,336	(446,318)		$ 130,429
Balance, end of period (in shares) at Sep. 30, 2021	31,455	13,009,477				13,009,477
Balance, beginning of period at Jun. 30, 2021	$ 99,770	$ 13	475,563	(438,447)
Balance, beginning of period (in shares) at Jun. 30, 2021	32,545	12,824,796
Increase (Decrease) in Shareholders' Equity
Conversion of preferred stock into common stock	$ (3,372)
Conversion of preferred stock into common stock (in shares)	(1,090)
Issuance of common stock upon the conversion of preferred stock			3,372
Issuance of common stock upon the conversion of preferred stock (in shares)		181,698
Expense related to warrants inherited in acquisition of Quellis			385
Issuance of common stock upon exercise of options			6
Fractional shares eliminated pursuant to reverse stock split		(9)
Stock-based compensation expense			1,010
Net loss				(7,871)		$ (7,871)
Balance, end of period at Sep. 30, 2021	$ 96,398	$ 13	$ 480,336	$ (446,318)		$ 130,429
Balance, end of period (in shares) at Sep. 30, 2021	31,455	13,009,477				13,009,477