REVENUE, DEFERRED REVENUE, AND REMAINING PERFORMANCE OBLIGATIONS - Sources of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Total revenue	$ 184,358	$ 141,860	$ 334,494	$ 281,977
Subscription revenue | Product Concentration Risk
Segment Reporting Information [Line Items]
Total revenue	177,217	132,562	321,638	263,818
Professional services revenue | Product Concentration Risk
Segment Reporting Information [Line Items]
Total revenue	$ 7,141	$ 9,298	$ 12,856	$ 18,159