STOCK-BASED AWARDS - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	$ 14,103	$ 19,151	$ 37,273	$ 36,196
Cost of revenue
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	2,122	1,786	4,823	2,922
Sales and marketing
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	5,628	6,809	14,212	12,856
Research and development
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	2,724	4,319	7,524	8,515
General and administrative
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	3,421	6,237	10,506	11,903
Restructuring
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	$ 208	$ 0	$ 208	$ 0