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Note 5 - Fair Value Measurements - Assets Measured on a Recurring Basis (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Total debt securities	$ 163,057,000	$ 114,360,000
Equity securities in financial institutions	833,000	609,000
Investment securities available for sale, at fair value	163,057,000	114,360,000
Subordinated Debt Securities [Member]
Total debt securities	32,620,000	21,297,000
Investment securities available for sale, at fair value	32,620,000	21,297,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	11,389,000	14,761,000
Investment securities available for sale, at fair value	11,389,000	14,761,000
Fair Value, Recurring [Member]
Total debt securities	163,057,000	114,360,000
Equity securities in financial institutions	833,000	609,000
Total	163,890,000	114,969,000
Investment securities available for sale, at fair value	163,057,000	114,360,000
Fair Value, Recurring [Member] | Subordinated Debt Securities [Member]
Total debt securities	32,620,000	21,297,000
Investment securities available for sale, at fair value	32,620,000	21,297,000
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	119,048,000	78,302,000
Investment securities available for sale, at fair value	119,048,000	78,302,000
Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	11,389,000	14,761,000
Investment securities available for sale, at fair value	11,389,000	14,761,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total debt securities	0	0
Equity securities in financial institutions	833,000	609,000
Total	833,000	609,000
Investment securities available for sale, at fair value	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Subordinated Debt Securities [Member]
Total debt securities	0	0
Investment securities available for sale, at fair value	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	0	0
Investment securities available for sale, at fair value	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	0	0
Investment securities available for sale, at fair value	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total debt securities	151,370,000	107,110,000
Equity securities in financial institutions	0	0
Total	151,370,000	107,110,000
Investment securities available for sale, at fair value	151,370,000	107,110,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Subordinated Debt Securities [Member]
Total debt securities	20,933,000	14,047,000
Investment securities available for sale, at fair value	20,933,000	14,047,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	119,048,000	78,302,000
Investment securities available for sale, at fair value	119,048,000	78,302,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	11,389,000	14,761,000
Investment securities available for sale, at fair value	11,389,000	14,761,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total debt securities	11,687,000	7,250,000
Equity securities in financial institutions	0	0
Total	11,687,000	7,250,000
Investment securities available for sale, at fair value	11,687,000	7,250,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Subordinated Debt Securities [Member]
Total debt securities	11,687,000	7,250,000
Investment securities available for sale, at fair value	11,687,000	7,250,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	0	0
Investment securities available for sale, at fair value	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	0	0
Investment securities available for sale, at fair value	$ 0	$ 0

X

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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