Balance Sheet Information - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 38,087	$ 36,731
Less: Accumulated depreciation and amortization	(27,467)	(25,996)
Land	1,770	1,770
Property and equipment, net	12,390	12,505
Building [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	6,868	6,868
Computers and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	10,309	10,039
Manufacturing and Test Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	16,454	15,394
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	1,438	1,437
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	2,998	2,973
Motor Vehicles [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 20	$ 20