Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, cost	$ 695,008	$ 834,232
Accumulated depreciation	(566,623)	(709,056)
Property and equipment, net	128,385	125,176	$ 144,887
Computer hardware
Property, Plant and Equipment [Line Items]
Property and equipment, cost	164,547	177,237
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment, cost	291,681	378,734
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, cost	88,136	117,740
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, cost	$ 150,644	$ 160,521