Property and Equipment, Net - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Computer hardware	$ 166,452	$ 162,346
Computer software	348,930	339,634
Furniture and equipment	97,270	96,536
Leasehold improvements	122,604	118,491
Other	10,032	9,560
Property and equipment, cost	745,288	726,567
Accumulated depreciation	(597,354)	(583,661)
Property and equipment, net	$ 147,934	$ 142,906