Fixed Assets (Schedule Of Fixed Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Property, Plant and Equipment [Abstract]
Fixed assets, at cost	$ 350,081	$ 337,362	$ 298,355
Less accumulated depreciation and amortization	171,159	164,614	147,977
Fixed assets, net	$ 178,922	$ 172,748	$ 150,378