Note 7 - Fair Value - Estimated Fair Value of Financial Instruments (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Fair value, held to maturity	$ 18,236,185	$ 18,033,093
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value, held to maturity	18,065,993	18,127,067
Mortgage loans held for sale	417,465	573,638
Federal Home Loan Bank stock	503,700	575,800
Interest-bearing deposits	304,755,581	291,995,483
Federal Home Loan Bank advances	3,000,000	3,000,000
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Loans, net	335,142,379	340,900,635
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Noninterest-bearing deposits	60,431,904	62,717,520
Securities sold under repurchase agreements	9,132,795	11,012,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair value, held to maturity	18,236,185	18,033,093
Mortgage loans held for sale	426,075	582,248
Federal Home Loan Bank stock	503,700	575,800
Interest-bearing deposits	297,345,581	281,761,483
Federal Home Loan Bank advances	2,983,000	2,971,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Loans, net	331,705,398	337,385,842
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Noninterest-bearing deposits	60,431,904	62,717,520
Securities sold under repurchase agreements	$ 9,132,795	$ 11,012,000

Fair value portion of interest-bearing deposits.

No definition available.

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- Definition

Fair value portion of noninterest-bearing deposit liabilities.

+ References

No definition available.

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- Definition

Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(3)(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

Fair value of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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- Definition

Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

+ References

No definition available.

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

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- Definition

Fair value portion of mortgage loans held-for-sale.

+ References

No definition available.

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- Definition

Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611

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