Revenue Concentrations, Significant Customers And Geographic Areas (Schedule Of Sales By Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue, Major Customer [Line Items]
Total export sales	$ 13,374	$ 10,915	$ 25,153	$ 21,521
Americas
Revenue, Major Customer [Line Items]
Total export sales	97	205	497	576
Europe
Revenue, Major Customer [Line Items]
Total export sales	2,369	1,606	4,472	4,264
China
Revenue, Major Customer [Line Items]
Total export sales	3,954	3,559	7,834	6,334
Taiwan
Revenue, Major Customer [Line Items]
Total export sales	763	999	2,479	3,144
Other Asia
Revenue, Major Customer [Line Items]
Total export sales	5,449	4,207	9,129	6,819
Other
Revenue, Major Customer [Line Items]
Total export sales	$ 742	$ 339	$ 742	$ 384