Property and Equipment, Net - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, cost	$ 841,771	$ 834,232
Accumulated depreciation	(716,249)	(709,056)
Property and equipment, net	125,522	125,176
Computer hardware
Property, Plant and Equipment [Line Items]
Property and equipment, cost	180,456	177,237
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment, cost	379,415	378,734
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, cost	109,060	107,421
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, cost	161,685	160,521
Other
Property, Plant and Equipment [Line Items]
Property and equipment, cost	$ 11,155	$ 10,319