Note 9 - Fair Value Measurements (Details Textual) - USD ($)	Sep. 30, 2015	Mar. 31, 2015
Fair Value, Inputs, Level 1 [Member] | Corporate Bond Securities [Member]
Available-for-sale Securities, Debt Securities	$ 82,588,628	$ 89,625,984
Fair Value, Inputs, Level 2 [Member] | Municipal Bonds [Member]
Available-for-sale Securities, Debt Securities	1,368,148	1,387,111
Corporate Bond Securities [Member]
Available-for-sale Securities, Debt Securities	82,588,628	89,625,984
Municipal Bonds [Member]
Available-for-sale Securities, Debt Securities	1,368,148	1,387,111
Available-for-sale Securities, Debt Securities	$ 83,956,776	$ 91,013,095