Note 4 - Loans and Allowance for Credit Losses - Loans Individually Evaluated for Impairment (Details) - USD ($)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Unpaid Contractual Principal Balance	$ 1,497,491	$ 5,148,185
Recorded Investment With No Allowance	757,033	1,428,073
Recorded Investment With Allowance	740,458	3,465,439
Total Recorded Investment	1,497,491	4,893,512
Related Allowance	229,776	440,041
Average Recorded Investment	2,561,705	4,674,918
Residential Portfolio Segment [Member] \| One- to Four-family Loan [Member]
Unpaid Contractual Principal Balance	1,130,849	2,688,197
Recorded Investment With No Allowance	746,579	1,428,073
Recorded Investment With Allowance	384,270	1,176,112
Total Recorded Investment	1,130,849	2,604,185
Related Allowance	119,228	242,587
Average Recorded Investment	1,795,888	2,634,763
Residential Portfolio Segment [Member] \| Multi-family Loans [Member]
Unpaid Contractual Principal Balance	0	0
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance	0	0
Total Recorded Investment	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Nonresidential Real Estate Portfolio Segment [Member]
Unpaid Contractual Principal Balance	355,203	2,435,424
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance	355,203	2,264,763
Total Recorded Investment	355,203	2,264,763
Related Allowance	110,055	185,172
Average Recorded Investment	749,271	2,030,894
Commercial Portfolio Segment [Member]
Unpaid Contractual Principal Balance	10,454	0
Recorded Investment With No Allowance	10,454	0
Recorded Investment With Allowance	0	0
Total Recorded Investment	10,454	0
Related Allowance	0	0
Average Recorded Investment	5,341	0
Consumer Portfolio Segment [Member]
Unpaid Contractual Principal Balance	0	0
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance	0	0
Total Recorded Investment	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Purchased Auto Loans [Member]
Unpaid Contractual Principal Balance	985	24,564
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance	985	24,564
Total Recorded Investment	985	24,564
Related Allowance	493	12,282
Average Recorded Investment	$ 11,205	$ 9,261

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

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