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, 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
Product Information [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
High precision 3D and 2D sensors [Member]
Product Information [Line Items]
Revenues									17,079	18,797	13,022
Semiconductor sensors [Member]
Product Information [Line Items]
Revenues									11,059	10,061	7,677
Inspection systems [Member]
Product Information [Line Items]
Revenues									19,468	28,680	13,578
Metrology products and services [Member]
Product Information [Line Items]
Revenues									$ 5,727	$ 8,702	$ 6,853