Purchased Intangible Assets and Goodwill (Composition of Purchased Intangibles) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Indefinite life intangible assets	$ 12,120	$ 11,888
Definite life intangible assets, net of accumulated amortization of $19,093 and $17,706	2,445	3,337
Total	14,565	15,225	$ 16,364
Definite life intangible assets, accumulated amortization	$ 19,093	$ 17,706