Income Taxes - Significant Components of Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carryforwards	$ 58,334	$ 57,716
Stock-based compensation	1,831	3,143
Reserves and allowances	170	337
U.S. tax credits and other credits	8,226	6,009
Capitalized research and development expenditures	11,184	3,988
Operating lease right-of-use assets	(197)	(338)
Operating lease liabilities	203	363
Other	226	371
Total deferred tax assets	79,977	71,589
Valuation allowance	(79,977)	(71,589)
Net deferred tax assets	$ 0	$ 0