Revenue - Changes in Deferred Revenue (Details) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020
Change In Contract With Customer, Liability [Roll Forward]
Beginning Balance	$ 60,295	$ 91,225
Performance obligations satisfied during the period that were included in the deferred revenue balance at the beginning of the year	(53,086)	(72,677)
Increases due to invoicing prior to satisfaction of performance obligations	55,101	52,345
Ending Balance	$ 62,310	$ 70,893