Equipment and Improvements - Summary of Equipment and Improvements (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Gross, Total	$ 13,398	$ 20,961
Less accumulated depreciation and amortization	(11,289)	(20,096)
Equipment and improvements, net	2,109	865
Computer Hardware, Software, and Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	9,079	14,658
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	2,808	5,316
Office Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	1,017	962
Construction In Progress [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	$ 494	$ 25