Note 8 - Loans and Allowance for Credit Losses - Loans by Risk Category (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Gross loans	$ 238,421,622	$ 238,554,157
Pass [Member]
Gross loans	80,494,229	81,726,371
Special Mention [Member]
Gross loans	369,617	335,758
Substandard [Member]
Gross loans	1,106,444	1,503,940
Doubtful [Member]
Gross loans
Not Rated [Member]
Gross loans	156,451,332	154,988,088
Residential Portfolio Segment [Member]
Gross loans	151,855,869	148,555,764
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member]
Gross loans	145,180,143	141,779,340
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member] | Pass [Member]
Gross loans	31,287,749	29,653,633
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member] | Special Mention [Member]
Gross loans	332,047	335,758
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member] | Substandard [Member]
Gross loans	662,122	1,048,744
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member] | Doubtful [Member]
Gross loans
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member] | Not Rated [Member]
Gross loans	112,898,225	110,741,205
Residential Portfolio Segment [Member] | Multi-family Loans [Member]
Gross loans	6,675,726	6,776,424
Residential Portfolio Segment [Member] | Multi-family Loans [Member] | Pass [Member]
Gross loans	0	0
Residential Portfolio Segment [Member] | Multi-family Loans [Member] | Special Mention [Member]
Gross loans
Residential Portfolio Segment [Member] | Multi-family Loans [Member] | Substandard [Member]
Gross loans	0	0
Residential Portfolio Segment [Member] | Multi-family Loans [Member] | Doubtful [Member]
Gross loans	0	0
Residential Portfolio Segment [Member] | Multi-family Loans [Member] | Not Rated [Member]
Gross loans	6,675,726	6,776,424
Nonresidential Real Estate Portfolio Segment [Member]
Gross loans	31,440,008	35,286,236
Nonresidential Real Estate Portfolio Segment [Member] | Pass [Member]
Gross loans	30,995,686	34,831,040
Nonresidential Real Estate Portfolio Segment [Member] | Special Mention [Member]
Gross loans
Nonresidential Real Estate Portfolio Segment [Member] | Substandard [Member]
Gross loans	444,322	455,196
Nonresidential Real Estate Portfolio Segment [Member] | Doubtful [Member]
Gross loans		0
Nonresidential Real Estate Portfolio Segment [Member] | Not Rated [Member]
Gross loans		0
Commercial Portfolio Segment [Member]
Gross loans	18,210,794	17,241,698
Commercial Portfolio Segment [Member] | Pass [Member]
Gross loans	18,210,794	17,241,698
Commercial Portfolio Segment [Member] | Special Mention [Member]
Gross loans		0
Commercial Portfolio Segment [Member] | Substandard [Member]
Gross loans
Commercial Portfolio Segment [Member] | Doubtful [Member]
Gross loans		0
Commercial Portfolio Segment [Member] | Not Rated [Member]
Gross loans		0
Consumer Portfolio Segment [Member]
Gross loans	16,708,018	15,390,263
Consumer Portfolio Segment [Member] | Pass [Member]
Gross loans	0	0
Consumer Portfolio Segment [Member] | Special Mention [Member]
Gross loans	37,570	0
Consumer Portfolio Segment [Member] | Substandard [Member]
Gross loans	0	0
Consumer Portfolio Segment [Member] | Doubtful [Member]
Gross loans	0	0
Consumer Portfolio Segment [Member] | Not Rated [Member]
Gross loans	16,670,448	15,390,263
Purchased Auto Loans [Member]
Gross loans	20,206,933	22,080,196
Purchased Auto Loans [Member] | Pass [Member]
Gross loans	0	0
Purchased Auto Loans [Member] | Special Mention [Member]
Gross loans	0	0
Purchased Auto Loans [Member] | Substandard [Member]
Gross loans
Purchased Auto Loans [Member] | Doubtful [Member]
Gross loans	0	0
Purchased Auto Loans [Member] | Not Rated [Member]
Gross loans	$ 20,206,933	$ 22,080,196