Fixed Assets (Schedule Of Fixed Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Property, Plant and Equipment [Abstract]
Fixed assets, at cost	$ 304,982	$ 291,776	$ 284,660
Less accumulated depreciation and amortization	153,732	141,176	136,021
Fixed assets, net	$ 151,250	$ 150,600	$ 148,639