Equipment and Improvements - Summary of Equipment and Improvements (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Gross, Total	$ 13,511	$ 13,398
Less accumulated depreciation and amortization	(11,341)	(11,289)
Equipment and improvements, net	2,170	2,109
Computer Hardware, Software, and Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	9,814	9,079
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	2,959	2,808
Office Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	714	1,017
Construction In Progress [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	$ 24	$ 494