Income Taxes - Components of Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Federal and state net operating losses	$ 55,481	$ 47,442
Federal and state research and experimentation credits	9,789	9,152
ASC 842 - lease liabilities	393	524
Stock based compensation	217	158
Deferred social security tax	116	212
Goodwill	97	154
Other	107	128
Total gross deferred tax assets	66,200	57,770
Less valuation allowance	(64,273)	(55,639)
Net deferred tax assets	1,927	2,131
Deferred tax liabilities:
Patent expenditures	(1,475)	(1,433)
ASC 842 - right of use assets	(288)	(386)
Fixed asset differences	(164)	(312)
Total gross deferred tax liabilities	(1,927)	(2,131)
Total net deferred tax assets and liabilities	$ 0	$ 0