Note 8 - Federal, State and Local Income Taxes (Details Textual)	3 Months Ended	9 Months Ended
	Jul. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%
Effective Income Tax Rate Reconciliation, Percent, Total		22.82%	27.05%
Open Tax Year		2017 2018 2019