Revenue Recognition - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020	Apr. 30, 2021
Revenue Recognition [Line Items]
Amounts received for reimbursement of travel and other out-of-pocket expenses	$ 12,000	$ 12,000	$ 40,000	$ 16,000
Deferred revenue recognized	17,100,000		27,100,000
Transaction price allocated to remaining performance obligations	123,300,000		123,300,000
Total deferred commissions	36,218,000		36,218,000		$ 37,682,000
Impairment losses	0	0	$ 0	0
Minimum
Revenue Recognition [Line Items]
Contractual period of maintenance contract			1 year
Maximum
Revenue Recognition [Line Items]
Contractual period of maintenance contract			3 years
Sales Commissions
Revenue Recognition [Line Items]
Total deferred commissions	3,700,000		$ 3,700,000		$ 3,900,000
Amortization of sales commissions	$ 500,000	$ 500,000	$ 1,000,000	$ 900,000