Note 5 - Investment Securities Available for Sale - Securities In a Continuous Unrealized Loss Position (Details) - USD ($)	Jun. 30, 2017	Mar. 31, 2017
Total fair value	$ 83,875,457	$ 93,126,015
Less than 12 months, gross unrealized losses	1,393,281	1,905,072
Less than 12 months, fair value	74,880,800	84,192,747
12 months or longer, gross unrealized losses	349,608	369,230
12 months or longer, fair value	8,994,657	8,933,268
Total gross unrealized losses	1,742,889	2,274,302
US Government Agencies Debt Securities [Member]
Total fair value	2,749,979	3,256,964
Less than 12 months, gross unrealized losses	13,142	13,393
Less than 12 months, fair value	2,749,979	3,256,964
12 months or longer, gross unrealized losses
12 months or longer, fair value
Total gross unrealized losses	13,142	13,393
Municipal Bonds [Member]
Total fair value	14,273,701	13,982,251
Less than 12 months, gross unrealized losses	618,977	950,496
Less than 12 months, fair value	14,273,701	13,982,251
12 months or longer, gross unrealized losses
12 months or longer, fair value
Total gross unrealized losses	618,977	950,496
Corporate Bond Securities [Member]
Total fair value	1,919,496	1,916,522
Less than 12 months, gross unrealized losses
Less than 12 months, fair value
12 months or longer, gross unrealized losses	80,504	83,478
12 months or longer, fair value	1,919,496	1,916,522
Total gross unrealized losses	80,504	83,478
Collateralized Mortgage Backed Securities [Member]
Total fair value	64,932,281	73,970,278
Less than 12 months, gross unrealized losses	761,162	941,183
Less than 12 months, fair value	57,857,120	66,953,532
12 months or longer, gross unrealized losses	269,104	285,752
12 months or longer, fair value	7,075,161	7,016,746
Total gross unrealized losses	$ 1,030,266	$ 1,226,935