Company Overview and Basis of Presentation - Proposed Merger with Zendesk (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
		Oct. 28, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Common stock, par value (in dollars per share)			$ 0.00001	$ 0.00001
Cost of revenue	[1],[2],[3]		$ 86,421	$ 83,917	$ 76,524
Research and development	[2],[3]		139,262	112,989	90,545
Sales and marketing	[1],[2],[3]		224,008	172,376	123,573
General and administrative	[2],[3]		106,667	$ 87,909	83,288
General and Administrative Expenses
Acquisition-related incremental expenses					$ 1,700
Momentive Global Inc.
Termination Fee		$ 150,000
Acquisition-related incremental expenses			12,800
Momentive Global Inc. | Cost of revenue
Acquisition-related incremental expenses			300
Momentive Global Inc. | Research and Development Expense
Acquisition-related incremental expenses			1,300
Momentive Global Inc. | Selling and Marketing Expense
Acquisition-related incremental expenses			1,200
Momentive Global Inc. | General and Administrative Expenses
Acquisition-related incremental expenses			$ 10,000
Momentive Global Inc. | Zendesk
Exchange ratio, share		0.225
Common stock, par value (in dollars per share)		$ 0.01

[1] Includes amortization of acquisition intangible assets as follows:

[2] Includes stock-based compensation, net of amounts capitalized as follows:

[3] Includes transaction expenses associated with the proposed merger with Zendesk. See Note 1 for additional information.