Leases - Balance Sheet Information (Details) - USD ($) $ in Thousands	Apr. 30, 2021	Apr. 30, 2020	May 01, 2019
Operating leases
Right-of-use assets	$ 5,094	$ 8,409	$ 11,500
Lease liabilities, current	3,894	3,533
Lease liabilities, non-current	1,735	5,647
Total operating lease liabilities	$ 5,629	$ 9,180	$ 12,400
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets, non-current	Other assets, non-current
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other long-term liabilities	Other long-term liabilities