SEGMENTS INFORMATION - Geographical Information of Long-Lived Assets Based on Physical Location (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 77,935	$ 73,616
Belarus
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	46,671	46,011
Russia
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	8,215	7,203
Ukraine
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	5,724	5,610
Hungary
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,972	3,485
United States
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	3,479	2,618
Poland
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	2,657	2,213
China
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	1,750	1,887
India
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	1,176	1,650
Bulgaria
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	931	722
Other
Long-Lived Assets by Geographical Areas [Line Items]
Long-lived assets	$ 3,360	$ 2,217