Property and Equipment, Net - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Computer hardware	$ 171,236	$ 162,346
Computer software	358,792	339,634
Furniture and equipment	97,300	96,536
Leasehold improvements	127,898	118,491
Other	10,268	9,560
Property and equipment, cost	765,494	726,567
Accumulated depreciation	(608,324)	(583,661)
Property and equipment, net	$ 157,170	$ 142,906