Revenue Concentrations, Significant Customers, and Geographic Areas (Summary Of Revenue By Product Line) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Product Information [Line Items]
Revenues	$ 16,852	$ 12,391	$ 15,044	$ 14,976	$ 18,063	$ 16,683	$ 15,854	$ 14,120	$ 59,263	$ 64,720
High Precision 3D and 2D Sensors [Member]
Product Information [Line Items]
Revenues									12,579	21,532
Inspection and Metrology Systems [Member]
Product Information [Line Items]
Revenues									32,713	29,582
Semiconductor Sensors [Member]
Product Information [Line Items]
Revenues									$ 13,971	$ 13,606