Note 13 - Fair Value Measurements - Securities Available for Sale Measured On a Recurring Basis (Details) - USD ($)	Sep. 30, 2017	Mar. 31, 2017
Investment securities available for sale, at fair value	$ 91,040,202	$ 102,429,128
Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	89,135,396	100,498,342
Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value	1,904,806	1,930,786
US Government Agencies Debt Securities [Member]
Investment securities available for sale, at fair value	2,744,435	3,512,303
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	2,744,435	3,512,303
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value
Municipal Bonds [Member]
Investment securities available for sale, at fair value	14,648,747	16,167,839
Municipal Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Municipal Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	12,746,294	14,239,526
Municipal Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value	1,902,453	1,928,313
Corporate Bond Securities [Member]
Investment securities available for sale, at fair value	2,950,506	1,916,522
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	2,950,506	1,916,522
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value
Collateralized Mortgage Backed Securities [Member]
Investment securities available for sale, at fair value	70,696,514	80,832,464
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	70,694,161	80,829,991
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value	$ 2,353	$ 2,473