Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation of property, plant and equipment	$ 70,834	$ 67,415	$ 66,122
Accumulated depreciation	729,669	681,641
Test Systems Leased By Customers
Property, Plant and Equipment [Line Items]
Machinery and equipment	5,400	5,500
Accumulated depreciation	$ 5,100	$ 5,200