Component of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 4,105	$ 3,553
Less: accumulated depreciation	(3,262)	(2,972)
Property and equipment, net	843	581
Office and computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	1,162	1,105
Software
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	907	886
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	1,158	990
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Gross	$ 878	$ 572