Revenue Concentrations, Significant Customers And Geographic Areas (Schedule Of Sales By Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue, Major Customer [Line Items]
Total export sales	$ 9,435	$ 16,256
Americas
Revenue, Major Customer [Line Items]
Total export sales	419	741
Europe
Revenue, Major Customer [Line Items]
Total export sales	2,815	4,115
Asia
Revenue, Major Customer [Line Items]
Total export sales	6,162	11,385
Other
Revenue, Major Customer [Line Items]
Total export sales	$ 39	$ 15