SEGMENT INFORMATION (Geographical Information of Long-Lived Assets Based on Physical Location) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 102,646	$ 86,419	$ 73,616
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	50,085	49,866	46,011
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	13,101	3,371	2,618
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	9,902	9,617	7,203
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	8,433	6,995	5,610
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	7,019	2,698	1,650
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,168	3,901	3,485
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,651	2,608	1,887
Poland
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,637	2,893	2,213
Other
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 5,650	$ 4,470	$ 2,939