Note 4 - Loans and Allowance for Credit Losses - Aging of the Recorded Investment in Loans (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Loans past due	$ 2,861,119	$ 3,820,602
Loans, current	206,646,418	159,012,976
Total loans	209,507,537	162,833,578
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	1,369,784	2,003,039
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	1,390,749	22,562
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	100,586	1,795,001
Residential Portfolio Segment [Member]
Total loans	129,782,859	109,054,297
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member]
Loans past due	1,945,764	2,991,635
Loans, current	122,172,571	100,880,051
Total loans	124,118,335	103,871,686
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	860,502	1,879,438
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	985,661	22,562
Residential Portfolio Segment [Member] | One- to Four-family Loan [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	99,601	1,089,635
Residential Portfolio Segment [Member] | Multi-family Loans [Member]
Loans past due	0	0
Loans, current	5,664,524	5,182,611
Total loans	5,664,524	5,182,611
Residential Portfolio Segment [Member] | Multi-family Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	0	0
Residential Portfolio Segment [Member] | Multi-family Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	0	0
Residential Portfolio Segment [Member] | Multi-family Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	0	0
Nonresidential Real Estate Portfolio Segment [Member]
Loans past due	873,564	798,934
Loans, current	31,259,530	21,761,233
Total loans	32,133,094	22,560,167
Nonresidential Real Estate Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	478,930	118,132
Nonresidential Real Estate Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	394,634	0
Nonresidential Real Estate Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due		680,802
Commercial Portfolio Segment [Member]
Loans past due	10,454	0
Loans, current	20,748,808	16,645,226
Total loans	20,759,262	16,645,226
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due		0
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	10,454	0
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	0	0
Consumer Portfolio Segment [Member]
Loans past due	0	1,105
Loans, current	6,281,712	2,858,598
Total loans	6,281,712	2,859,703
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	0	1,105
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	0	0
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	0	0
Purchased Auto Loans [Member]
Loans past due	31,337	28,928
Loans, current	20,519,273	11,685,257
Total loans	20,550,610	11,714,185
Purchased Auto Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans past due	30,352	4,364
Purchased Auto Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans past due	0	0
Purchased Auto Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans past due	$ 985	$ 24,564