Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Offering to Astellas	Public Offering	At-the-Market Offering	Common Stock	Common Stock Offering to Astellas	Common Stock Public Offering	Common Stock At-the-Market Offering	Additional Paid-in Capital	Additional Paid-in Capital Offering to Astellas	Additional Paid-in Capital Public Offering	Additional Paid-in Capital At-the-Market Offering	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Balance at Dec. 31, 2020	$ 251,302									$ 312,428				$ (61,126)
Balance, shares at Dec. 31, 2020						37,761,435
Stock-based compensation	18,604									18,604
Issuance of common stock, upon vesting and settlement of restricted stock units, shares						712,510
Net loss	(174,523)													(174,523)
Balance at Dec. 31, 2021	$ 95,383	$ 222								331,032				(235,649)	$ 222
Balance, shares at Dec. 31, 2021	38,473,945					38,473,945
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2016-02 [Member]
Stock-based compensation	$ 18,275									18,275
Issuance of common stock			$ 13,764	$ 27,457	$ 11,609				$ 1		$ 13,764	$ 27,457	$ 11,608
Issuance of common stock, shares							7,266,342	14,765,226	2,000,000
Issuance of common stock, upon vesting and settlement of restricted stock units, shares						628,921
Issuance of common stock under ESPP	253									253
Issuance of common stock under ESPP, shares						73,073
Net loss	(166,014)													(166,014)
Balance at Dec. 31, 2022	$ 949					$ 1				$ 402,389				$ (401,441)
Balance, shares at Dec. 31, 2022	63,207,507					63,207,507