Income Taxes - Summary of Major Components of Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 46,120	$ 40,436
Research and development credit carryforwards	3,669	3,321
Capitalized research and development costs	11,123	13,334
Other	271	11
Stock compensation	1,987	1,941
Total deferred tax assets	63,170	59,043
Valuation allowance	(63,170)	(59,043)
Net deferred tax assets	$ 0	$ 0