GEOGRAPHICAL INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 93,767	$ 89,912	$ 85,682	$ 83,225	$ 79,344	$ 75,575	$ 72,483	$ 69,098	$ 66,489	$ 63,676	$ 63,183	$ 60,041	$ 352,586	$ 296,500	$ 253,388
Property and Equipment	52,835				35,732								52,835	35,732
Americas
Segment Reporting Information [Line Items]
Revenue													316,427	266,034	227,914
Property and Equipment	45,639				27,270								45,639	27,270
Europe
Segment Reporting Information [Line Items]
Revenue													36,159	30,466	$ 25,474
Property and Equipment	$ 7,196				$ 8,462								$ 7,196	$ 8,462