Note B - Summary of Significant Accounting Policies - Property and Equipment, Estimated Useful Lives (Details)	12 Months Ended
	Apr. 30, 2021
Minimum [Member] | Furniture, Fixtures and Equipment [Member]
Property and equipment (Year)	3 years
Minimum [Member] | Leasehold Improvements [Member]
Property and equipment (Year)	5 years
Minimum [Member] | Building and Building Improvements [Member]
Property and equipment (Year)	18 years
Maximum [Member] | Furniture, Fixtures and Equipment [Member]
Property and equipment (Year)	7 years
Maximum [Member] | Leasehold Improvements [Member]
Property and equipment (Year)	15 years
Maximum [Member] | Building and Building Improvements [Member]
Property and equipment (Year)	39 years