Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Noncurrent deferred tax assets:
Stock-based compensation	$ 3,665	$ 2,281
Accrued expenses and other	1,007	795
Research credit carryforward	6,776	6,182
Fixed assets	345	392
Capitalized start-up costs and other intangibles	3,618	1,859
Net operating loss carryforwards	113,410	74,566
Deferred tax assets, gross	128,821	86,075
Valuation allowance	(123,108)	(81,337)
Net noncurrent deferred tax asset	5,713	4,738
Noncurrent deferred tax liabilities
Fixed assets and other	(1,445)	(686)
Purchase accounting intangibles	(5,660)	(8,772)
Net noncurrent deferred tax liability	(7,105)	(9,458)
Net deferred tax liability	$ (1,392)	$ (4,720)