Summary of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total gross value	$ 133,028	$ 133,569
Less accumulated depreciation	(83,533)	(83,274)
Total net value	49,495	50,295
Land
Property, Plant and Equipment [Line Items]
Total gross value	2,458	2,458
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total gross value	16,610	15,515
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total gross value	106,641	102,146
Office furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Total gross value	4,701	5,016
Automotive equipment
Property, Plant and Equipment [Line Items]
Total gross value	398	387
Construction in progress
Property, Plant and Equipment [Line Items]
Total gross value	$ 2,220	$ 8,047