Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 102,378	$ 91,914
Accumulated depreciation and amortization	(76,297)	(72,464)
Property and equipment, net	26,081	19,450
Buildings and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	26,289	19,841
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	25,835	23,893
Capitalized Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	36,639	36,429
Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 13,615	$ 11,751