Note 5 - Gross Unrealized Losses and Fair Value of Investments (Details) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Mar. 31, 2015
Corporate Bond Securities [Member]
Fair market value less than 12 months	$ 8,834,101	$ 8,834,101	$ 3,015,900
Gross unrealized losses less than 12 months		(9,840)	(163)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2,597,444	2,597,444	2,590,240
Gross unrealized losses greater than 12 months		(7,775)	(16,208)
Total Fair Market Value	11,431,545	11,431,545	5,606,140
Total Gross Unrealized Losses	$ (17,615)	$ (17,615)	$ (16,371)
Municipal Bonds [Member]
Fair market value less than 12 months
Gross unrealized losses less than 12 months
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value
Gross unrealized losses greater than 12 months
Total Fair Market Value
Total Gross Unrealized Losses
Fair market value less than 12 months	$ 8,834,101	$ 8,834,101	$ 3,015,900
Gross unrealized losses less than 12 months		(9,840)	(163)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2,595,544	2,595,544	2,590,240
Gross unrealized losses greater than 12 months		(7,775)	(16,208)
Total Fair Market Value	$ 11,431,545	11,431,545	5,606,140
Total Gross Unrealized Losses		$ (17,615)	$ (16,371)