Consolidated and Combined Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common stock	Net parent investment	Additional paid-in capital	Accumulated other comprehensive loss	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2019		0
Beginning balance at Dec. 31, 2019	$ 43,692	$ 0	$ 43,692	$ 0	$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	60,997		60,997
Transfers from bluebird bio	90,054		90,054
Net loss	(120,114)		(120,114)
Ending balance (in shares) at Dec. 31, 2020		0
Ending balance at Dec. 31, 2020	74,629	$ 0	74,629	0	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	9,012			9,012
Stock-based compensation - bluebird allocation	44,626		44,626
Transfers from bluebird bio	517,706		517,936		(230)
Consummation of spin-off transaction (in shares)		23,369,000
Consummation of spin-off transaction, which includes issuance of pre-funded warrants to purchase 757,575 shares of common stock (refer to Note 9, Stockholders’ equity)	0	$ 2	(384,472)	384,470
Vesting of restricted stock units (in shares)		7,000
Issuance of unrestricted stock awards to settle accrued employee compensation (in shares)		209,000
Issuance of unrestricted stock awards to settle accrued employee compensation	6,544			6,544
Other comprehensive loss	(482)				(482)
Net loss	$ (292,213)		(252,719)			(39,494)
Ending balance (in shares) at Dec. 31, 2021	23,585,000	23,585,000
Ending balance at Dec. 31, 2021	$ 359,822	$ 2	0	400,026	(712)	(39,494)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	$ 41,040			41,040
Vesting of restricted stock units (in shares)		374,000
Exercise of stock options (in shares)	2,000
Exercise of stock options	$ 17			17
Issuance of common stock in private placement, net of issuance costs (in shares)	13,934,000
Issuance of common stock in private placement, net of issuance costs	$ 165,533	$ 2		165,531
Purchase of common stock under ESPP (in shares)		33,000
Purchase of common stock under ESPP	372			372
Other comprehensive loss	(2,165)				(2,165)
Net loss	$ (254,153)					(254,153)
Ending balance (in shares) at Dec. 31, 2022	37,928,000	37,928,000
Ending balance at Dec. 31, 2022	$ 310,466	$ 4	$ 0	$ 606,986	$ (2,877)	$ (293,647)