Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 28, 2021	Sep. 30, 2021	Dec. 31, 2020
Subsequent Events
Common stock, par value (in dollars per share)		$ 0.00001	$ 0.00001
Subsequent Events | Momentive Global Inc.
Subsequent Events
Termination Fee	$ 150.0
Subsequent Events | Momentive Global Inc. | Zendesk
Subsequent Events
Exchange ratio, share	0.225
Common stock, par value (in dollars per share)	$ 0.01