Leases - Lease Maturity Schedule (Details) - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Finance Leases
2021	$ 3,118
2022	3,110
2023	3,116
2024	2,565
2025	1,167
Thereafter	10,764
Finance Leases	23,840
Less amount representing interest	7,094
Finance lease liabilities (Note 7)	16,746
Operating leases
2021	1,829
2022	1,814
2023	1,717
2024	1,683
2025	1,686
Thereafter	25,335
Total minimum lease payments	34,064
Less amount representing interest	12,468
Present value of net minimum lease payments	$ 21,596
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Capital leases
2020		$ 3,103
2021		3,109
2022		3,096
2023		3,098
2024		2,548
Thereafter		9,215
Total minimum lease payments		24,169
Less amount representing interest		7,689
Present value of net minimum lease payments		16,480
Operating leases
2020		1,703
2021		1,547
2022		1,354
2023		1,228
2024		1,066
Thereafter		10,438
Total minimum lease payments		$ 17,336