Property and Equipment, Net - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Computer hardware	$ 154,591	$ 159,309
Computer software	324,617	312,968
Furniture and equipment	105,877	105,262
Leasehold improvements	113,692	113,782
Other	9,317	9,045
Property and equipment, cost	708,094	700,366
Accumulated depreciation	(583,445)	(578,612)
Property and equipment, net	$ 124,649	$ 121,754