Property, Plant, and Equipment - Property, Plant, and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant and equipment, gross	$ 157,752	$ 123,495
Less: accumulated depreciation	(79,704)	(69,503)
Property, Plant and Equipment, Net, Total	78,048	53,992
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and equipment, gross	3,951	3,951
Building [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and equipment, gross	24,589	23,280
Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and equipment, gross	33,189	28,049
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and equipment, gross	6,513	5,237
Hardware And Software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and equipment, gross	61,835	39,409
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and equipment, gross	21,312	18,726
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and equipment, gross	$ 6,363	$ 4,843