Income Taxes - Schedule of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 288,264	$ 251,331
Research and development tax credits	30,002	29,290
Orphan drug credits	24,524	24,524
Capitalized research and development	37,357	33,813
Stock-based compensation	6,965	5,445
Interest	1,359	398
Other	3,308	2,255
Total deferred tax assets	391,779	347,056
Deferred tax liabilities:
Other	(1,608)	(1,295)
Total deferred tax liabilities	(1,608)	(1,295)
Less: valuation allowance	(390,171)	(345,761)
Net deferred tax liabilities	$ 0	$ 0