Note 9 - Fair Value Measurement - Assets and Liabilities Measured at Fair Value on a Non-recurring Basis (Details) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Other real estate, Total gain (loss)	$ 0		$ 0
Asset, Total gain (loss)	0	$ 118,000	118,000
Impaired loans, Total gain (loss)			118,000
Fair Value, Nonrecurring [Member]
Other real estate	763,000		707,000
Assets	893,000		837,000
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Other real estate	0		0
Assets	0		0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Other real estate	0		0
Assets	0		0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Other real estate	763,000		707,000
Assets	893,000		837,000
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member]
Other real estate, Total gain (loss)			0
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Nonrecurring [Member]
Impaired loans	130,000		130,000
Other real estate	347,000		347,000
Other real estate, Total gain (loss)	0
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Impaired loans	0		0
Other real estate	0		0
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Impaired loans	0		0
Other real estate	0		0
Commercial Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Impaired loans	130,000		130,000
Other real estate	347,000		347,000
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Other real estate, Total gain (loss)			0
Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Fair Value, Nonrecurring [Member]
Other real estate	360,000		360,000
Other real estate, Total gain (loss)	0		360,000
Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Other real estate	0
Other real estate, Total gain (loss)			0
Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Other real estate	0
Other real estate, Total gain (loss)			0
Commercial Portfolio Segment [Member] \| Construction Loans [Member] \| Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Other real estate	360,000
Other real estate, Total gain (loss)			$ 360,000
Residential Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Nonrecurring [Member]
Other real estate	56,000
Other real estate, Total gain (loss)	0
Residential Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Other real estate	0
Residential Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Other real estate	0
Residential Portfolio Segment [Member] \| Real Estate Loan [Member] \| Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Other real estate	$ 56,000

Represents the amount of gain (loss) on fair value adjustments of impaired loans during the period.

No definition available.

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- Definition

Represents the amount of gain (loss) on fair value adjustments of other real estate during the period.

+ References

No definition available.

+ Details

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- Definition

Represents fair value portion of impaired loans.

+ References

No definition available.

+ Details

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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

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- Definition

Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold or retired, and gain (loss) from the write down of assets from their carrying value to fair value.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

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- Definition

Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ 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 210.9-03.10(4))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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