Leases - Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 1,697
2022	1,851
2023	1,818
2024	1,844
2025	1,867
Thereafter	7,268
Total	$ 16,345
Future Minimum Lease Payments [Abstract]
2020		$ 1,471
2021		1,445
2022		1,404
2023		1,419
2024		1,002
Thereafter		3,398
Total		$ 10,139