Note 6 - Investment Securities Available for Sale - Securities In a Continuous Unrealized Loss Position (Details) - USD ($)	Mar. 31, 2017	Mar. 31, 2016
Total gross unrealized losses	$ 2,274,302	$ 408,489
Total fair value	93,126,015	29,264,964
Less than 12 months, gross unrealized losses	1,905,072	39,972
Less than 12 months, fair value	84,192,747	7,092,287
12 months or longer, gross unrealized losses	369,230	368,517
12 months or longer, fair value	8,933,268	22,172,677
US Government Agencies Debt Securities [Member]
Total gross unrealized losses	13,393	6,752
Total fair value	3,256,964	2,244,157
Less than 12 months, gross unrealized losses	13,393	6,752
Less than 12 months, fair value	3,256,964	2,244,157
12 months or longer, gross unrealized losses
12 months or longer, fair value
Municipal Bonds [Member]
Total gross unrealized losses	950,496	140
Total fair value	13,982,251	480,168
Less than 12 months, gross unrealized losses	950,496	140
Less than 12 months, fair value	13,982,251	480,168
12 months or longer, gross unrealized losses
12 months or longer, fair value
Corporate Bond Securities [Member]
Total gross unrealized losses	83,478	101,360
Total fair value	1,916,522	1,898,640
Less than 12 months, gross unrealized losses
Less than 12 months, fair value
12 months or longer, gross unrealized losses	83,478	101,360
12 months or longer, fair value	1,916,522	1,898,640
Collateralized Mortgage Backed Securities [Member]
Total gross unrealized losses	1,226,935	300,237
Total fair value	73,970,278	24,641,999
Less than 12 months, gross unrealized losses	941,183	33,080
Less than 12 months, fair value	66,953,532	4,367,962
12 months or longer, gross unrealized losses	285,752	267,157
12 months or longer, fair value	$ 7,016,746	$ 20,274,037