Revenue - Deferred Revenue Balance (Details) - USD ($) $ in Thousands		Jan. 31, 2021	Apr. 30, 2020	Jan. 31, 2020	Apr. 30, 2019
Revenue from Contract with Customer [Abstract]
Deferred revenue, current	[1]	$ 59,950	$ 53,537
Deferred revenue, non-current		2,360	6,758
Total deferred revenue		$ 62,310	$ 60,295	$ 70,893	$ 91,225

[1] Including amounts from a related party of $9,358 and $1,499 as of January 31, 2021 and April 30, 2020, respectively.