Other Financial Statement Information - Property, Plant and Equipment - Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment - Gross	$ 309,790	$ 294,710
Less accumulated depreciation	(175,350)	(170,692)
Property, plant and equipment - Net	134,440	124,018
Land and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment - Gross	21,168	22,218
Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment - Gross	83,480	82,811
Machinery, Equipment and Aircraft [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment - Gross	187,372	180,221
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment - Gross	$ 17,770	$ 9,460