SEGMENT AND GEOGRAPHICAL INFORMATION (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) segment
Segment and geographical information
Number of segments | segment		1
Revenues	$ 275,769	$ 269,554
Fixed assets	6,636	5,229
Americas
Segment and geographical information
Revenues	159,108	161,845
Fixed assets	5,319	3,495
Europe
Segment and geographical information
Revenues	95,130	82,910
Fixed assets	1,162	1,390
Asia Pacific
Segment and geographical information
Revenues	21,531	24,799
Fixed assets	155	344
Germany
Segment and geographical information
Revenues	47,200	40,000
United Kingdom
Segment and geographical information
Revenues	18,600	14,800
Australia
Segment and geographical information
Revenues	$ 17,800	$ 18,600