Significant Customer and Geographic Information - Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of revenues by geographical area
Revenues	$ 50,024	$ 48,837	$ 41,804
United States
Schedule of revenues by geographical area
Revenues	15,469	21,310	23,293
India
Schedule of revenues by geographical area
Revenues	5,639	3,578	1,026
Singapore
Schedule of revenues by geographical area
Revenues	6,165	3,836	963
United Kingdom
Schedule of revenues by geographical area
Revenues	51	10,851	8,721
Switzerland
Schedule of revenues by geographical area
Revenues	13,216	2,315	1,574
Rest of world
Schedule of revenues by geographical area
Revenues	$ 9,484	$ 6,947	$ 6,227