Fixed Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation	$ 22,698	$ 21,003	$ 20,890
Property, Plant and Equipment, Gross	233,908	214,335
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(156,822)	(138,528)
Property, Plant and Equipment, Net	77,086	75,807
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	190,784	177,823
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	35,481	33,137
Land, Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 7,643	$ 3,375