Note 11 - Information As to Employee Stock Purchase, Savings, and Similar Plans (Details Textual) - USD ($)	3 Months Ended			6 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		100.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent		3.00%
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 26,831		$ 21,275	$ 55,415	$ 46,656