SEGMENTS INFORMATION - Geographical Information of Long-Lived Assets Based on Physical Location (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 98,450	$ 86,419
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	48,426	49,866
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	11,541	3,371
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	10,521	9,617
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	7,472	2,698
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	6,818	6,995
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,350	3,901
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,275	2,608
Other
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 7,047	$ 7,363