Note 4 - Loans and Allowance for Credit Losses - Carrying Amount of Loans Acquired in Twin Oaks Merger (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gross loans	$ 209,507,537	$ 162,833,578
Less: Allowance for loan losses	(2,472,446)	(2,247,449)	$ (2,224,006)
Loans, net	207,035,091	160,586,129
Twin Oaks [Member]
Gross loans	17,828,475	21,663,937
Less: Allowance for loan losses	(135,000)	(100,000)
Loans, net	17,693,475	21,563,937
Residential Portfolio Segment [Member]
Gross loans	129,782,859	109,054,297
Residential Portfolio Segment [Member] \| Twin Oaks [Member]
Gross loans	15,076,954	18,335,050
Residential Portfolio Segment [Member] \| One- to Four-family Loan [Member]
Gross loans	124,118,335	103,871,686
Less: Allowance for loan losses	(1,477,419)	(1,426,954)	(1,727,582)
Residential Portfolio Segment [Member] \| One- to Four-family Loan [Member] \| Twin Oaks [Member]
Gross loans	14,811,329	18,062,672
Residential Portfolio Segment [Member] \| Multi-family Loans [Member]
Gross loans	5,664,524	5,182,611
Less: Allowance for loan losses	(21,970)	(93,481)	(142,237)
Residential Portfolio Segment [Member] \| Multi-family Loans [Member] \| Twin Oaks [Member]
Gross loans	265,625	272,378
Nonresidential Real Estate Portfolio Segment [Member]
Gross loans	32,133,094	22,560,167
Less: Allowance for loan losses	(371,093)	(367,326)	(198,340)
Nonresidential Real Estate Portfolio Segment [Member] \| Twin Oaks [Member]
Gross loans	2,120,630	2,352,952
Commercial Portfolio Segment [Member]
Gross loans	20,759,262	16,645,226
Less: Allowance for loan losses	(153,596)	(96,823)	(51,306)
Commercial Portfolio Segment [Member] \| Twin Oaks [Member]
Gross loans	571,538	779,595
Consumer Portfolio Segment [Member]
Gross loans	6,281,712	2,859,703
Less: Allowance for loan losses	(140,269)	(79,253)	$ (37,187)
Consumer Portfolio Segment [Member] \| Twin Oaks [Member]
Gross loans	59,353	196,340
Non-mortgage Loans [Member]
Gross loans	79,724,678	53,779,281
Non-mortgage Loans [Member] \| Twin Oaks [Member]
Gross loans	$ 2,751,521	$ 3,328,887

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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