Equipment, Furniture and Leasehold Improvements - Equipment, Furniture and Leasehold Improvements (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total	$ 3,329	$ 4,478
Less: accumulated depreciation and amortization	(2,340)	(3,389)
Equipment, furniture and leasehold improvements, net	989	1,089
Computer equipment and software [Member]
Property, Plant and Equipment [Line Items]
Total	1,819	2,929
Office furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Total	321	357
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total	$ 1,189	$ 1,192