Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 15,038	$ 14,451
Accumulated depreciation	(12,921)	(12,035)
Property and equipment, net	2,117	2,416
Building and Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,863	1,884
Furniture, Fixtures and Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,933	2,002
Plant and Machinery
Property Plant And Equipment [Line Items]
Property and equipment, gross	9,319	8,848
Purchased Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,923	$ 1,717