Leases - Summary of Supplemental Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	Jul. 31, 2020	Apr. 30, 2020
Finance Leases:
Property and equipment, at cost	$ 4,811	$ 4,281
Accumulated depreciation	(1,806)	(1,485)
Property and equipment, net	3,005	$ 2,796
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]		us-gaap:PropertyPlantAndEquipmentNet
Other accrued liabilities	1,191	$ 1,241
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]		us-gaap:OtherAccruedLiabilitiesCurrent
Other liabilities	1,945	$ 1,634
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]		us-gaap:OtherLiabilitiesNoncurrent
Total finance lease liabilities	$ 3,136	$ 2,875
Weighted average remaining lease terms:
Operating leases	5 years 3 months 18 days	5 years 6 months
Finance leases	3 years 2 months 12 days	2 years 10 months 24 days
Weighted average discount rate:
Operating leases	4.80%	4.80%
Finance leases	4.20%	4.10%