Segment Information - Summary of Segment Performance and Make Decisions About Resource Allocation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Revenues	$ 251	$ 33,492
Operating expenses	67,533	64,163
Other income, net	1,909	2,023
Provision for income taxes	0	(72)
Net loss	(65,373)	(28,720)
AB-101 [Member]
Segment Reporting Information [Line Items]
Operating expenses	19,978	14,090
Other programs [Member]
Segment Reporting Information [Line Items]
Operating expenses	330	3,797
Personnel-Related [Member]
Segment Reporting Information [Line Items]
Operating expenses	30,465	28,610
Other [Member]
Segment Reporting Information [Line Items]
Operating expenses	$ 16,760	$ 17,666