Revenue Concentrations, Significant Customers And Geographic Areas (Schedule Of Sales By Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue, Major Customer [Line Items]
Total export sales	$ 24,409	$ 17,540	$ 60,091	$ 42,694
Americas
Revenue, Major Customer [Line Items]
Total export sales	620	94	2,145	592
Europe
Revenue, Major Customer [Line Items]
Total export sales	3,024	2,221	9,541	6,693
China
Revenue, Major Customer [Line Items]
Total export sales	9,502	4,829	23,210	12,662
Taiwan
Revenue, Major Customer [Line Items]
Total export sales	2,081	2,237	3,754	4,716
Other Asia
Revenue, Major Customer [Line Items]
Total export sales	9,142	7,706	20,825	16,864
Other
Revenue, Major Customer [Line Items]
Total export sales	$ 40	$ 453	$ 616	$ 1,167