SEGMENT INFORMATION (Physical Locations and Values of Long-Lived Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 169,533	$ 165,259	$ 102,646
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	73,988	75,984	50,085
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	30,980	24,652	8,433
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	15,718	15,637	13,101
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	15,036	17,980	9,902
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	7,079	7,443	7,019
Poland
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	5,434	5,029	2,637
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	5,365	5,201	3,168
Spain
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,799	1,106	875
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,722	3,036	2,651
Mexico
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,419	2,353	812
Other
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 7,993	$ 6,838	$ 3,963