Supplemental Consolidated Balance Sheet Information (Property And Equipment, Net) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 218,629	$ 210,104
Less: accumulated depreciation and amortization	(130,490)	(127,151)
Property and equipment, net	88,139	82,953
Furniture, Fixtures and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	71,326	69,210
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	91,696	83,766
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 55,607	$ 57,128