Revenue Concentrations, Significant Customers And Geographic Areas (Schedule Of Sales By Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue, Major Customer [Line Items]
Total export sales	$ 14,467	$ 11,780
Americas
Revenue, Major Customer [Line Items]
Total export sales	783	401
Europe
Revenue, Major Customer [Line Items]
Total export sales	3,500	2,103
China
Revenue, Major Customer [Line Items]
Total export sales	5,163	3,880
Taiwan
Revenue, Major Customer [Line Items]
Total export sales	730	1,716
Other Asia
Revenue, Major Customer [Line Items]
Total export sales	4,143	3,680
Other
Revenue, Major Customer [Line Items]
Total export sales	$ 148	$ 0