Note 11 - Information as to Employee Stock Purchase, Savings, and Similar Plans (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
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	$ 21,275	$ 21,990	$ 46,656	$ 46,056