Property and Equipment, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and equipment - gross	$ 127,874	$ 128,502
Less accumulated depreciation	(100,952)	(99,575)
Total property and equipment, net	26,922	28,927
Land
Property Plant And Equipment [Line Items]
Property and equipment - gross	875	875
Buildings
Property Plant And Equipment [Line Items]
Property and equipment - gross	$ 17,389	17,389
Buildings | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Life (Years)	39 years
Buildings | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Life (Years)	40 years
Building Improvements
Property Plant And Equipment [Line Items]
Property and equipment - gross	$ 34,957	34,957
Building Improvements | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Life (Years)	5 years
Building Improvements | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Life (Years)	40 years
Machinery and Equipment
Property Plant And Equipment [Line Items]
Property and equipment - gross	$ 62,681	62,992
Machinery and Equipment | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Life (Years)	3 years
Machinery and Equipment | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Life (Years)	15 years
Furniture, fixtures and office equipment
Property Plant And Equipment [Line Items]
Property and equipment - gross	$ 3,556	3,556
Furniture, fixtures and office equipment | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Life (Years)	5 years
Furniture, fixtures and office equipment | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Life (Years)	10 years
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Estimated Useful Life (Years)	3 years
Property and equipment - gross	$ 8,416	8,531
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment - gross		$ 202