Note 8 - Federal, State and Local Income Taxes - Effective Income Tax Rate Reconciliation (Details)	6 Months Ended		12 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Apr. 30, 2021	Apr. 30, 2020
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	1.11%	4.22%
Non-taxable SBA loan forgiveness	(2.75%)	0.00%
Effect of dividends received deductions	(0.33%)	(0.28%)
Other, net	0.02%	0.00%
Effective income tax rate	19.05%	24.94%