Note 9 - Lease Commitments (Details Textual)			12 Months Ended
	Nov. 30, 2016 USD ($) ft²	Feb. 29, 2016 USD ($) ft²	Apr. 30, 2024 USD ($)	Apr. 30, 2023 USD ($)	Apr. 30, 2022 USD ($)	Oct. 03, 2021 USD ($)	May 01, 2019 USD ($)	Oct. 30, 2016 USD ($)
Assets [Abstract]
Property, Plant and Equipment, Net			$ 4,440,000	$ 5,788,000
Operating Lease, Right-of-Use Asset			4,090,000	5,300,000			$ 9,575,000
Operating Lease, Liability, Total			4,784,000				10,340,000
Lease Incentive Receivable							$ 765,000
Operating Lease, Expense			1,499,000	$ 1,499,000	$ 1,499,000
Operating Lease, Payments			$ 1,634,000
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]			Property, Plant and Equipment, Net	Property, Plant and Equipment, Net			Property, Plant and Equipment, Net
Sublease to American Building Maintenance Industries, Incorporated [Member]
Area of Real Estate Property (Square Foot) | ft²	24,726
Operating Leases, Annual Base Rent	$ 1,126,000
Base Rent Increase, Percent	2.25%
Security Deposit						$ 305,000		$ 469,000
Annual Rental Expenditure, Initial, Decrease, Percentage	23.00%
Lessee Leasing Arrangements, Allowance	$ 417,000
Lessee Leasing Arrangements, Allowance, Six Months of Free Rent Payment	$ 563,000
Seagis Property Group LP (the "Landlord") [Member] | Value Line Distribution Center ("VLDC") [Member]
Area of Real Estate Property (Square Foot) | ft²		24,110
Security Deposit		$ 32,146
Base Rent Increase Amount		$ 237,218