Summary of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total gross value	$ 145,351	$ 138,451
Less accumulated depreciation	(91,714)	(89,199)
Total net value	53,637	49,252
Land
Property, Plant and Equipment [Line Items]
Total gross value	2,548	2,548
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total gross value	17,902	17,555
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total gross value	109,901	109,064
Office furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Total gross value	6,067	5,655
Automotive equipment
Property, Plant and Equipment [Line Items]
Total gross value	1,694	1,116
Construction in progress
Property, Plant and Equipment [Line Items]
Total gross value	$ 7,239	$ 2,513