Note 6 - Loans Receivable and Allowance for Loan Losses - Summary of Troubled Debt Restructurings (Details)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)
Troubled debt restructurings	$ 3,700,241	$ 3,747,382
Number of contracts	17	16
Performing Financial Instruments [Member]
Troubled debt restructurings	$ 1,863,864	$ 1,905,602
Nonperforming Financial Instruments [Member]
Troubled debt restructurings	1,836,377	1,841,780
Real Estate Loans [Member] | Residential [Member]
Troubled debt restructurings	$ 1,543,426	$ 1,556,571
Number of contracts	14	13
Real Estate Loans [Member] | Residential [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	$ 1,253,861	$ 1,261,603
Real Estate Loans [Member] | Residential [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	289,565	294,968
Real Estate Loans [Member] | Investor Loans [Member]
Troubled debt restructurings	$ 0	$ 0
Number of contracts	0	0
Real Estate Loans [Member] | Investor Loans [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	$ 0	$ 0
Real Estate Loans [Member] | Investor Loans [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	0	0
Real Estate Loans [Member] | Commercial [Member]
Troubled debt restructurings	$ 1,546,812	$ 1,546,812
Number of contracts	2	2
Real Estate Loans [Member] | Commercial [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	$ 0	$ 0
Real Estate Loans [Member] | Commercial [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	1,546,812	1,546,812
Real Estate Loans [Member] | Commercial construction [Member]
Troubled debt restructurings	$ 0	$ 0
Number of contracts	0	0
Real Estate Loans [Member] | Commercial construction [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	$ 0	$ 0
Real Estate Loans [Member] | Commercial construction [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	0	0
Commercial Portfolio Segment [Member]
Troubled debt restructurings		$ 643,999
Number of contracts		1
Commercial Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings		$ 643,999
Commercial Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	0	0
Home equity loans [Member]
Troubled debt restructurings	$ 0	$ 0
Number of contracts	0	0
Home equity loans [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	$ 0	$ 0
Home equity loans [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	0	0
Consumer Portfolio Segment [Member]
Troubled debt restructurings	$ 610,003	$ 0
Number of contracts	1	0
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Troubled debt restructurings	$ 610,003	$ 0
Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructurings	$ 0	$ 0