Stock-Based Awards - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	$ 19,151	$ 16,032	$ 36,196	$ 35,511
Cost of revenue
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	1,786	1,021	2,922	2,023
Sales and marketing
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	6,809	6,545	12,856	12,791
Research and development
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	4,319	2,417	8,515	4,725
General and administrative
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	6,237	5,300	11,903	9,787
Restructuring
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Share based compensation expense	$ 0	$ 749	$ 0	$ 6,185