Fixed Assets - Textual (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation	$ 27,111	$ 23,873	$ 22,293
Capital Lease Obligations
Property, Plant and Equipment [Line Items]
Capital leased assets, gross	1,447	1,903
Capital leases, lessee balance sheet, assets by major class, accumulated depreciation	$ 780	$ 1,176