SEGMENT INFORMATION (Geographical Information of Long-Lived Assets Based on Physical Location) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 86,419	$ 73,616	$ 60,499
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	49,866	46,011	44,879
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	9,617	7,203	2,084
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	6,995	5,610	4,487
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,901	3,485	2,485
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,371	2,618	1,969
Poland
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,893	2,213	1,088
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,698	1,650	1,099
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,608	1,887	514
Bulgaria
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	922	722	317
Other
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 3,548	$ 2,217	$ 1,577