REVENUE - Geographic Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 256,268	$ 225,951	$ 895,469	$ 718,917
Percent of total revenue	100.00%	100.00%	100.00%	100.00%
U.S.
Disaggregation of Revenue [Line Items]
Revenue	$ 132,016	$ 120,971	$ 515,881	$ 436,199
Other Americas
Disaggregation of Revenue [Line Items]
Revenue	17,510	10,737	43,469	35,009
United Kingdom (“U.K.”)
Disaggregation of Revenue [Line Items]
Revenue	25,982	25,150	86,747	68,246
Europe (excluding U.K.), Middle East, and Africa
Disaggregation of Revenue [Line Items]
Revenue	46,306	39,656	143,763	106,472
Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue	$ 34,454	$ 29,437	$ 105,609	$ 72,991
Total revenue | U.S. | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Percent of total revenue	52.00%	53.00%	58.00%	61.00%
Total revenue | Other Americas | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Percent of total revenue	7.00%	5.00%	5.00%	5.00%
Total revenue | United Kingdom (“U.K.”) | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Percent of total revenue	10.00%	11.00%	10.00%	9.00%
Total revenue | Europe (excluding U.K.), Middle East, and Africa | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Percent of total revenue	18.00%	18.00%	15.00%	15.00%
Total revenue | Asia-Pacific | Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Percent of total revenue	13.00%	13.00%	12.00%	10.00%