Property and Equipment, Net - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment, cost	$ 666,597	$ 665,684
Accumulated depreciation	(562,896)	(555,867)
Property and equipment, net	103,701	109,817
Computer hardware
Property, Plant and Equipment [Line Items]
Property and equipment, cost	160,685	159,180
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment, cost	251,477	250,585
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, cost	91,345	91,112
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, cost	$ 163,090	$ 164,807