Summary of Net Deferred Tax Assets and Net Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Capitalized intangible assets for tax purposes	$ (38)	$ (42)
Reserves not currently deductible	1,384	1,666
Deferred revenue	44	38
Stock options	4,694	4,153
State taxes	5	5
Income tax credits	3,429	3,820
Inventory	974	549
Property and equipment	302	126
Unrealized gain on foreign currency	111	85
Disallowed Interest	708	120
Lease liability	129
Net operating losses	42,527	37,205
Total deferred tax assets	54,269	47,725
Valuation allowance	(53,222)	(46,967)
Net deferred tax assets	1,047	758
Capitalized intangible assets	(708)	(629)
Right of use asset	(109)
Other	(179)	(206)
Total deferred tax liabilities	(996)	(835)
Net deferred tax assets	51
Net deferred tax liabilities	$ (78)	$ (77)