Note 10 - Lines of Credit and Federal Home Loan Bank Advances - Federal Home Loan Bank Advances (Details) - USD ($)		6 Months Ended	12 Months Ended
		Sep. 30, 2017	Mar. 31, 2017
Amount		$ 52,572,568	$ 35,577,250
Premium on borrowings assumed		284,850	547,649
Total FHLB borrowings		52,857,418	36,124,899
Borrowing One [Member] | Federal Home Loan Bank Advances [Member]
Amount	[1]	$ 5,550,000	$ 5,550,000
Rate	[1]	1.17%	0.94%
Maturity Date	[1]	Dec. 11, 2017	Jun. 09, 2017
Borrowing Two [Member] | Federal Home Loan Bank Advances [Member]
Amount	[2]	$ 6,000,000	$ 6,000,000
Rate	[2]	1.19%	0.93%
Maturity Date	[2]	Dec. 29, 2017	Jun. 29, 2017
Borrowing Three [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 1,500,000	$ 1,000,000
Rate		3.23%	4.24%
Maturity Date		Nov. 24, 2017	Jul. 31, 2017
Borrowing Four [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 1,500,000	$ 5,000,000
Rate		3.40%	4.28%
Maturity Date		Nov. 27, 2017	Jul. 31, 2017
Borrowing Five [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 1,000,000	$ 1,000,000
Rate		1.18%	4.01%
Maturity Date		Nov. 30, 2017	Aug. 21, 2017
Borrowing Six [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 1,000,000	$ 1,000,000
Rate		2.60%	0.91%
Maturity Date		Jul. 02, 2018	Aug. 31, 2017
Borrowing Seven [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 1,000,000	$ 1,500,000
Rate		3.05%	3.23%
Maturity Date		Jul. 03, 2018	Nov. 24, 2017
Borrowing Eight [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 5,000,000	$ 1,500,000
Rate		3.94%	3.40%
Maturity Date		Jul. 23, 2018	Nov. 27, 2017
Borrowing Nine [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 1,000,000	$ 1,000,000
Rate		1.28%	2.60%
Maturity Date		Jul. 31, 2018	Jul. 02, 2018
Borrowing Ten [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 1,000,000	$ 1,000,000
Rate		1.40%	3.05%
Maturity Date		Aug. 21, 2018	Jul. 03, 2018
Borrowing Eleven [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 3,000,000	$ 5,000,000
Rate		1.41%	3.94%
Maturity Date		Aug. 27, 2018	Jul. 23, 2018
Borrowing Twelve [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 4,000,000	$ 5,000,000
Rate		1.30%	3.38%
Maturity Date		Aug. 27, 2018	Sep. 19, 2018
Borrowing Thirteen [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 5,000,000	$ 1,000,000
Rate		3.38%	2.60%
Maturity Date		Sep. 19, 2018	Oct. 02, 2018
Borrowing Fourteen [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 1,000,000
Rate		2.60%
Maturity Date		Oct. 02, 2018
Borrowing Fifteen [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 3,000,000
Rate		1.38%
Maturity Date		Jul. 31, 2019
Borrowing Sixteen [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 3,000,000
Rate		1.59%
Maturity Date		Aug. 26, 2019
Borrowing Seventeen [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 3,000,000
Rate		1.34%
Maturity Date		Aug. 26, 2019
Borrowing Eighteen [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 3,000,000
Rate		1.42%
Maturity Date		Aug. 26, 2019
Borrowing Nineteen [Member] | Federal Home Loan Bank Advances [Member]
Amount		$ 3,000,000
Rate		1.48%
Maturity Date		Aug. 25, 2021
Automobile Note [Member]
Rate		1.95%
Automobile Note [Member] | Notes Payable to Banks [Member]
Amount		$ 22,568	$ 27,250
Rate		1.95%	1.95%
Maturity Date		Feb. 17, 2020	Feb. 17, 2020

[1] FHLB Advance is tied to three derivative cash flow hedges in increments of $1.85 million each. The three individual cash flow hedges are for a term of five, seven and ten years, respectively and are tied to the 3-month LIBOR rate. In order for the cash flow hedges to remain effective, the corresponding FHLB Advance will have to be renewed every three months until the respective cash flow hedge matures.

[2] FHLB Advance is tied to three derivative cash flow hedges in increments of $2.0 million each. The three individual cash flow hedges are for a term of five, seven and ten years, respectively and are tied to the 3-month LIBOR rate. In order for the cash flow hedges to remain effective, the corresponding FHLB Advance will have to be renewed every three months until the respective cash flow hedge matures.