SEGMENTS INFORMATION - Geographical Information of Long-Lived Assets Based on Physical Location (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 99,465	$ 86,419
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	48,728	49,866
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	11,542	3,371
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	10,279	9,617
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	8,529	6,995
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	6,783	2,698
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,198	3,901
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,830	2,608
Other locations
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 7,576	$ 7,363