Revenue Concentrations, Significant Customers, and Geographic Areas (Schedule Of Revenue By Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue, Major Customer [Line Items]
Revenues	$ 13,176	$ 11,828	$ 16,409	$ 11,920	$ 13,455	$ 15,040	$ 18,631	$ 19,114	$ 53,333	$ 66,240	$ 41,130
United States [Member]
Revenue, Major Customer [Line Items]
Revenues									15,361	12,754	11,452
Netherlands [Member]
Revenue, Major Customer [Line Items]
Revenues									2,786	8,033	4,533
Other Europe [Member]
Revenue, Major Customer [Line Items]
Revenues									8,948	9,183	7,462
China [Member]
Revenue, Major Customer [Line Items]
Revenues									6,899	14,626	4,060
Singapore [Member]
Revenue, Major Customer [Line Items]
Revenues									4,424	2,767	1,010
South Korea [Member]
Revenue, Major Customer [Line Items]
Revenues									2,643	7,634	3,462
Japan [Member]
Revenue, Major Customer [Line Items]
Revenues									7,177	4,505	4,802
Other Asia [Member]
Revenue, Major Customer [Line Items]
Revenues									3,685	5,106	2,580
Other [Member]
Revenue, Major Customer [Line Items]
Revenues									$ 1,410	$ 1,632	$ 1,769