SEGMENT INFORMATION (Geographical Information of Long-Lived Assets Based on Physical Location) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 165,259	$ 102,646	$ 86,419
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	75,984	50,085	49,866
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	24,652	8,433	6,995
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	17,980	9,902	9,617
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	15,637	13,101	3,371
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	7,443	7,019	2,698
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	5,201	3,168	3,901
Poland
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	5,029	2,637	2,893
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,036	2,651	2,608
Other
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 10,297	$ 5,650	$ 4,470