Income Taxes - Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets
Net operating loss carryforwards	$ 25,646	$ 78,619
GSK licenses	47,014	0
Research and development tax credit carryforwards	7,612	14,294
Capitalized research and development expenses, net	21,342	11,613
Other	6,264	10,264
Total gross deferred tax asset	107,878	114,790
Valuation allowance	(107,878)	(114,790)	$ (102,444)
Net deferred tax assets	$ 0	$ 0