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, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue, Major Customer [Line Items]
Total export sales	$ 21,215	$ 13,374	$ 35,684	$ 25,153
Americas
Revenue, Major Customer [Line Items]
Total export sales	741	97	1,524	497
Europe
Revenue, Major Customer [Line Items]
Total export sales	3,017	2,369	6,518	4,472
China
Revenue, Major Customer [Line Items]
Total export sales	8,545	3,954	13,709	7,834
Taiwan
Revenue, Major Customer [Line Items]
Total export sales	943	763	1,673	2,479
Other Asia
Revenue, Major Customer [Line Items]
Total export sales	7,541	5,449	11,683	9,129
Other
Revenue, Major Customer [Line Items]
Total export sales	$ 428	$ 742	$ 577	$ 742