Note 15 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Interest-bearing demand deposits in other financial institutions	$ 116,518,226	$ 87,557,842
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	122,003,730	92,671,909
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Interest-bearing demand deposits in other financial institutions	6,230,414	250,000
Federal Home Loan Bank stock	3,852,100	3,757,500
Mortgage loans held for sale	5,259,413	2,786,564
Interest receivable	4,801,074	3,511,875
Deposits	926,919,606	821,406,532
Federal Home Loan Bank advances	66,000,000	65,000,000
Interest payable	724,200	793,746
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Loans, net	771,447,520	720,732,402
Note payable to bank	0	11,200,000
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Subordinated Debentures Issued to Capital Trusts [Member]
Subordinated debentures	15,465,000	15,465,000
Reported Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Subordinated Notes, Net [Member]
Subordinated debentures	19,552,770
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	122,003,730	92,671,909
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Interest-bearing demand deposits in other financial institutions	6,255,065	250,315
Federal Home Loan Bank stock	3,852,100	3,757,500
Mortgage loans held for sale	5,259,413	2,786,564
Interest receivable	4,801,074	3,511,875
Deposits	928,280,339	822,046,988
Federal Home Loan Bank advances	66,095,943	66,015,635
Interest payable	724,200	793,746
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Loans, net	769,903,643	723,363,117
Note payable to bank	0	11,200,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Subordinated Debentures Issued to Capital Trusts [Member]
Subordinated debentures	15,465,000	$ 15,465,000
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Subordinated Notes, Net [Member]
Subordinated debentures	$ 19,552,770

Fair value portion of interest payable.

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Fair value portion of interest receivable.

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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.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

+ References

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Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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

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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))
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For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=117340910&loc=d3e59706-112781

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

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

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- Definition

Fair value portion of notes payable.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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