Note 8 - Fair Value - Estimated Fair Value of Financial Instruments (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Fair value, held to maturity	$ 20,914,769
Securities held to maturity	20,914,769
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	27,139,193	$ 26,462,106
Noninterest-bearing deposits	132,629,508	124,175,615
Securities sold under repurchase agreements	4,083,707	5,414,026
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Certificates of deposit in other banks	350,000	350,000
Accrued interest receivable	1,562,014	1,609,063
Fair value, held to maturity	21,343,559	21,851,975
Mortgage loans held for sale	285,000	126,500
Restricted stock, at cost	695,000	675,400
Bank owned life insurance	11,609,153	11,556,163
Securities held to maturity	21,343,559	21,851,975
Interest-bearing deposits	501,151,145	502,239,055
Federal Home Loan Bank advances	5,000,000	5,000,000
Long-term debt	16,553,090	16,978,905
Accrued interest payable	276,573	295,910
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value, held to maturity	0	3,073,040
Securities held to maturity	0	3,073,040
Loans, net	483,908,857	482,011,334
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	27,139,193	26,462,106
Noninterest-bearing deposits	132,629,508	124,175,615
Securities sold under repurchase agreements	4,083,707	5,414,026
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Certificates of deposit in other banks	350,000	350,000
Accrued interest receivable	1,562,014	1,609,063
Fair value, held to maturity	20,914,769	22,805,601
Mortgage loans held for sale	287,015	128,829
Restricted stock, at cost	695,000	675,400
Bank owned life insurance	11,609,153	11,556,163
Securities held to maturity	20,914,769	22,805,601
Interest-bearing deposits	499,421,145	502,396,172
Federal Home Loan Bank advances	4,764,000	4,967,000
Long-term debt	16,718,129	17,298,111
Accrued interest payable	276,573	295,910
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair value, held to maturity	0	3,073,040
Securities held to maturity	0	3,073,040
Loans, net	$ 486,099,069	$ 487,012,970

Fair value portion of accrued interest payable.

No definition available.

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Fair value portion of accrued interest receivable.

+ References

No definition available.

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Fair value portion of certificates of deposit in other banks.

+ References

No definition available.

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Fair value portion of interest-bearing deposits.

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No definition available.

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Fair value portion of noninterest-bearing deposit liabilities.

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No definition available.

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

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- Definition

Fair value portion of the amount that could be realized under a life insurance contract or contracts owned by the entity, commonly known as corporate-owned life insurance (COLI) or bank-owned life insurance (BOLI).

+ 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 https://asc.fasb.org/extlink&oid=126897435&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 https://asc.fasb.org/extlink&oid=126970911&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
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-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
-Paragraph 5A
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-URI https://asc.fasb.org/extlink&oid=126970911&loc=SL120269820-111563

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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 https://asc.fasb.org/subtopic&trid=2196772

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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

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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.

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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 https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611

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