Balance Sheet Components - Schedule of Significant Changes in Unbilled Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Unbilled Account Receivable [Roll Forward]
Beginning balance	$ 1,710	$ 1,139	$ 1,114
Amounts transferred to accounts receivable from unbilled accounts receivable presented at the beginning of the period	(1,710)	(1,139)	(1,114)
Revenue recognized during the period in excess of invoices issued	2,622	1,710	1,139
Ending balance	$ 2,622	$ 1,710	$ 1,139