Accrued Expenses and Other Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Accrued external research and development expenses	$ 11,230	$ 9,273
Accrued payroll and related expenses	12,312	8,521
Accrued milestone payments	85	2,058
Accrued professional fees	2,263	854
Accrued other	2,562	2,941
Accrued governmental rebates	2,300
Strimvelis liability - current portion	3,685	671
Total accrued expenses and other current liabilities	$ 34,437	$ 24,318