Note 4 - Investment Securities Available for Sale - Securities In a Continuous Unrealized Loss Position (Details) - USD ($)	Sep. 30, 2018	Mar. 31, 2018
Securities available for sale, less than 12 months, gross unrealized losses	$ 185,975	$ 405,150
Securities available for sale, less than 12 months, fair value	6,707,755	16,603,971
Securities available for sale, 12 months or longer, gross unrealized losses	3,286,003	2,470,786
Securities available for sale, 12 months or longer, fair value	61,910,008	56,340,528
Securities available for sale, total gross unrealized losses	3,471,978	2,875,936
Securities available for sale, total fair value	68,617,763	72,944,499
US Government Agencies Debt Securities [Member]
Securities available for sale, less than 12 months, gross unrealized losses		21,163
Securities available for sale, less than 12 months, fair value		723,023
Securities available for sale, 12 months or longer, gross unrealized losses	35,162	13,534
Securities available for sale, 12 months or longer, fair value	2,711,667	1,995,625
Securities available for sale, total gross unrealized losses	35,162	34,697
Securities available for sale, total fair value	2,711,667	2,718,648
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale, less than 12 months, gross unrealized losses
Securities available for sale, less than 12 months, fair value
Securities available for sale, 12 months or longer, gross unrealized losses	884,033	729,077
Securities available for sale, 12 months or longer, fair value	11,492,431	11,705,991
Securities available for sale, total gross unrealized losses	884,033	729,077
Securities available for sale, total fair value	11,492,431	11,705,991
Corporate Debt Securities [Member]
Securities available for sale, less than 12 months, gross unrealized losses
Securities available for sale, less than 12 months, fair value
Securities available for sale, 12 months or longer, gross unrealized losses	50,868	45,924
Securities available for sale, 12 months or longer, fair value	1,949,132	1,954,076
Securities available for sale, total gross unrealized losses	50,868	45,924
Securities available for sale, total fair value	1,949,132	1,954,076
Collateralized Mortgage Backed Securities [Member]
Securities available for sale, less than 12 months, gross unrealized losses	185,975	383,987
Securities available for sale, less than 12 months, fair value	6,707,755	15,880,948
Securities available for sale, 12 months or longer, gross unrealized losses	2,315,940	1,682,251
Securities available for sale, 12 months or longer, fair value	45,756,778	40,684,836
Securities available for sale, total gross unrealized losses	2,501,915	2,066,238
Securities available for sale, total fair value	$ 52,464,533	$ 56,565,784

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
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-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
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