Fixed Assets - Schedule of Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Cost	$ 216,735	$ 213,905
Accumulated Depreciation	(128,546)	(123,599)
Net Book Value	88,189	90,306
Computers, furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Cost	100,276	101,806
Accumulated Depreciation	(73,060)	(74,429)
Net Book Value	27,216	27,377
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Cost	116,459	112,099
Accumulated Depreciation	(55,486)	(49,170)
Net Book Value	$ 60,973	$ 62,929