Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Abstract]
Computer hardware	$ 162,346	$ 159,309
Computer software	339,634	312,968
Furniture and equipment	96,536	105,262
Leasehold improvements	118,491	113,782
Other	9,560	9,045
Property and equipment, cost	726,567	700,366
Accumulated depreciation	(583,661)	(578,612)
Property and equipment, net	$ 142,906	$ 121,754	$ 112,644