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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue, Major Customer [Line Items]
Total export sales	$ 17,540	$ 9,574	$ 42,694	$ 31,094
Americas
Revenue, Major Customer [Line Items]
Total export sales	94	418	592	994
Europe
Revenue, Major Customer [Line Items]
Total export sales	2,221	1,926	6,693	6,189
China
Revenue, Major Customer [Line Items]
Total export sales	4,829	2,135	12,662	8,469
Taiwan
Revenue, Major Customer [Line Items]
Total export sales	2,237	842	4,716	3,986
Other Asia
Revenue, Major Customer [Line Items]
Total export sales	7,706	4,005	16,864	10,824
Other
Revenue, Major Customer [Line Items]
Total export sales	$ 453	$ 248	$ 1,167	$ 632