Note 8 - Federal, State and Local Income Taxes - Effective Income Tax Rate Reconciliation (Details)	9 Months Ended		12 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	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	2.11%	2.30%
Non-taxable SBA loan forgiveness	(1.93%)	0.00%
Effect of dividends received deductions	(0.26%)	(0.28%)
Other, net	0.02%	0.01%
Effective income tax rate	20.94%	23.03%