Property and Equipment, Net - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, cost	$ 756,477	$ 834,232
Accumulated depreciation	(630,257)	(709,056)
Property and equipment, net	126,220	125,176
Computer hardware
Property, Plant and Equipment [Line Items]
Property and equipment, cost	170,610	177,237
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment, cost	288,814	378,734
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, cost	113,869	107,421
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, cost	171,375	160,521
Other
Property, Plant and Equipment [Line Items]
Property and equipment, cost	$ 11,809	$ 10,319