Leases - Additional Information Related to Leases (Details) - USD ($)	3 Months Ended
	Jul. 31, 2020	Jul. 31, 2019
Cash Paid For Amounts Included In The Measurement Of Lease Liabilities [Abstract]
Operating cash flows for finance leases	$ 14,000	$ 53,000
Operating cash flows for operating leases	6,142,000	5,109,000
Financing cash flows for financing leases	92,000	589,000
Right-of-use assets obtained in exchange for new finance lease liabilities	109	485
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 155	$ 21,118
Weighted average remaining lease term (years)
Weighted average remaining lease term - finance leases	3 years 2 months 19 days	3 years 6 months 7 days
Weighted average remaining lease term - operating leases	7 years 3 months 29 days	6 years 8 months 15 days
Weighted average discount rate
Weighted average discount rate - finance leases (as a percent)	3.08%	3.23%
Weighted average discount rate - operating leases (as a percent)	3.54%	4.25%