STOCK-BASED AWARDS - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	$ 17,924	$ 19,518	$ 55,197	$ 55,714
Cost of revenue
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	2,205	1,748	7,028	4,670
Sales and marketing
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	7,197	7,915	21,409	20,771
Research and development
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	4,283	4,285	11,807	12,800
General and administrative
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	4,047	5,570	14,553	17,473
Restructuring
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	$ 192	$ 0	$ 400	$ 0