Leases - Components of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Leases [Abstract]
Operating lease cost	$ 2,172	$ 2,184	$ 4,284	$ 3,963
Short-term lease cost	721	859	1,352	1,531
Variable lease cost	(65)	189	289	308
Total lease cost	$ 2,828	$ 3,232	$ 5,925	$ 5,802