Fixed Assets - Schedule of Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Cost	$ 183,510	$ 160,111
Accumulated Depreciation	(105,133)	(96,554)
Net Book Value	78,377	63,557
Computers, furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Cost	91,909	87,213
Accumulated Depreciation	(64,030)	(62,901)
Net Book Value	27,879	24,312
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Cost	91,601	72,898
Accumulated Depreciation	(41,103)	(33,653)
Net Book Value	$ 50,498	$ 39,245