Note 8 - Loans and Allowance for Credit Losses - Loans Individually Evaluated for Impairment (Details) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Unpaid Contractual Principal Balance	$ 1,106,444	$ 1,503,940
Recorded Investment With No Allowance	426,803	569,629
Recorded Investment With Allowance	679,641	934,311
Total Recorded Investment	1,106,444	1,503,940
Related Allowance	129,110	217,313
Average Recorded Investment	1,323,128	1,447,500
Unpaid Contractual Principal Balance	1,106,444	1,503,940
Recorded Investment With No Allowance	426,803	569,629
Recorded Investment With Allowance	679,641	934,311
Related Allowance	129,110	217,313
Average Recorded Investment	1,323,128	1,447,500
Residential Portfolio Segment [Member] \| One- to Four-family Loan [Member]
Unpaid Contractual Principal Balance	662,122	1,048,744
Recorded Investment With No Allowance	414,670	427,825
Recorded Investment With Allowance	247,452	620,919
Total Recorded Investment	662,122	1,048,744
Related Allowance	90,189	178,639
Average Recorded Investment	875,235	1,074,284
Unpaid Contractual Principal Balance	662,122	1,048,744
Recorded Investment With No Allowance	414,670	427,825
Recorded Investment With Allowance	247,452	620,919
Related Allowance	90,189	178,639
Average Recorded Investment	875,235	1,074,284
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
Unpaid Contractual Principal Balance	0	0
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Nonresidential Real Estate Portfolio Segment [Member]
Unpaid Contractual Principal Balance	444,322	455,196
Recorded Investment With No Allowance	12,133	141,804
Recorded Investment With Allowance	432,189	313,392
Total Recorded Investment	444,322	455,196
Related Allowance	38,921	38,674
Average Recorded Investment	447,893	366,226
Unpaid Contractual Principal Balance	444,322	455,196
Recorded Investment With No Allowance	12,133	141,804
Recorded Investment With Allowance	432,189	313,392
Related Allowance	38,921	38,674
Average Recorded Investment	447,893	366,226
Commercial Portfolio Segment [Member]
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance
Recorded Investment With Allowance	0	0
Total Recorded Investment
Related Allowance	0	0
Average Recorded Investment		1,282
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance
Recorded Investment With Allowance	0	0
Related Allowance	0	0
Average Recorded Investment		1,282
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
Unpaid Contractual Principal Balance	0	0
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Purchased Auto Loans [Member]
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance
Total Recorded Investment
Related Allowance
Average Recorded Investment		5,708
Unpaid Contractual Principal Balance
Recorded Investment With No Allowance	0	0
Recorded Investment With Allowance
Related Allowance
Average Recorded Investment		$ 5,708

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524

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