Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Intangible assets	$ 192,444	$ 187,839
Share-based compensation	31,712	29,673
Net operating loss carryforwards	329,135	228,985
Research and development credits	67,667	57,419
Orphan drug credits	34,023	30,160
Development derivative liability	75,190	79,374
Convertible debt	5,582	6,850
Fixed Assets	18
Lease liability	2,888	4,304
Accruals	17,401	16,272
Total deferred tax assets	756,060	640,876
Deferred tax liabilities:
Fixed assets		(91)
Right-of-use asset	(2,672)	(4,032)
481(a) adjustment		(233)
Total deferred tax liabilities	(2,672)	(4,356)
Net deferred tax assets before allowance:	753,388	636,520
Less valuation allowance	$ (753,388)	$ (636,520)