Note 6 - Loans Receivable and Allowance for Loan Losses - Outstanding Commitments and Unused Lines of Credit (Details) - USD ($)	Jun. 30, 2017	Mar. 31, 2017
Unused commercial lines of credit [Member]
Outstanding commitments and unused lines of credit	$ 13,942,528	$ 10,733,345
Unused home equity lines of credit [Member]
Outstanding commitments and unused lines of credit	22,566,463	22,993,289
Unused consumer lines of credit [Member]
Outstanding commitments and unused lines of credit	30,760	1,110,155
Residential Mortgage Loan Commitments [Member]
Outstanding commitments and unused lines of credit
Residential construction loan commitments [Member]
Outstanding commitments and unused lines of credit	8,435,236	8,047,156
Commercial construction loan commitments [Member]
Outstanding commitments and unused lines of credit	6,812,988	7,091,564
Home equity loan commitments [Member]
Outstanding commitments and unused lines of credit		84,000
Commercial loan commitments [Member]
Outstanding commitments and unused lines of credit	360,000	1,089,218
Standby letters of credit [Member]
Outstanding commitments and unused lines of credit	$ 206,367	$ 472,354