Note 5 - Gross Unrealized Losses and Fair Value of Investments (Details) - USD ($)	6 Months Ended	12 Months Ended
	Sep. 30, 2016	Mar. 31, 2016
Corporate Bond Securities [Member]
Fair market value, less than 12 months	$ 10,965,905	$ 3,003,606
Gross unrealized losses, less than 12 months	(34,699)	(6,703)
Fair market value, greater than 12 months		2,599,870
Gross unrealized losses, greater than 12 months		(4,121)
Total Fair Market Value	10,965,905	5,603,476
Total Gross Unrealized Losses	(34,699)	(10,824)
Municipal Bonds [Member]
Fair market value, less than 12 months	1,324,301
Gross unrealized losses, less than 12 months	(271)
Fair market value, greater than 12 months
Gross unrealized losses, greater than 12 months
Total Fair Market Value	1,324,301
Total Gross Unrealized Losses	(271)
Fair market value, less than 12 months	12,290,206	3,003,606
Gross unrealized losses, less than 12 months	(34,970)	(6,703)
Fair market value, greater than 12 months		2,599,870
Gross unrealized losses, greater than 12 months		(4,121)
Total Fair Market Value	12,290,206	5,603,476
Total Gross Unrealized Losses	$ (34,970)	$ (10,824)