Note 7 - Property, Plant, and Equipment - Schedule of Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	Jul. 31, 2023	Apr. 30, 2023
Property, plant, and equipment, gross	$ 83,524	$ 84,593
Accumulated depreciation	(25,189)	(25,526)
Total property, plant and equipment	58,335	59,067
Land [Member]
Property, plant, and equipment, gross	4,751	4,751
Building and Building Improvements [Member]
Property, plant, and equipment, gross	47,867	47,867
Aircraft [Member]
Property, plant, and equipment, gross	7,193	8,515
Machinery and Equipment [Member]
Property, plant, and equipment, gross	5,627	5,547
Furniture and Fixtures [Member]
Property, plant, and equipment, gross	14,054	13,881
Leasehold Improvements [Member]
Property, plant, and equipment, gross	$ 4,032	$ 4,032