Note 3 - Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
With no related allowance recorded, unpaid principal balance	$ 26,892,000	$ 13,687,000
With no related allowance recorded, principal balance	24,738,000	12,245,000
With no related allowance recorded, average recorded principal balance	17,315,000	16,675,000
With related allowance recorded, unpaid principal balance	2,266,000	2,398,000
With related allowance recorded, principal balance	2,220,000	2,377,000
Related allowance	551,000	1,623,000
With related allowance recorded, average recorded principal balance	2,742,000	8,833,000
Total unpaid principal balance	29,158,000	16,085,000
Total principal balance	26,958,000	14,622,000
Total average recorded principal balance	20,057,000	25,508,000
Commercial Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	21,365,000	9,136,000
With no related allowance recorded, principal balance	21,176,000	9,068,000
With no related allowance recorded, average recorded principal balance	13,652,000	13,394,000
With related allowance recorded, unpaid principal balance	1,268,000	1,538,000
With related allowance recorded, principal balance	1,239,000	1,536,000
Related allowance	138,000	1,184,000
With related allowance recorded, average recorded principal balance	1,726,000	7,515,000
Total unpaid principal balance	22,633,000	10,674,000
Total principal balance	22,415,000	10,604,000
Total average recorded principal balance	15,378,000	20,909,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial [Member]
With no related allowance recorded, unpaid principal balance	6,242,000	8,129,000
With no related allowance recorded, principal balance	6,242,000	8,129,000
With no related allowance recorded, average recorded principal balance	7,874,000	11,610,000
With related allowance recorded, unpaid principal balance	343,000	460,000
With related allowance recorded, principal balance	343,000	458,000
Related allowance	53,000	202,000
With related allowance recorded, average recorded principal balance	971,000	5,709,000
Commercial Portfolio Segment [Member] \| Vacant Land and Land Development and Residential Construction Loan [Member]
With no related allowance recorded, unpaid principal balance	0	85,000
With no related allowance recorded, principal balance	0	85,000
With no related allowance recorded, average recorded principal balance	187,000	89,000
With related allowance recorded, unpaid principal balance	0	0
With related allowance recorded, principal balance	0	0
Related allowance	0	0
With related allowance recorded, average recorded principal balance	77,000	0
Commercial Portfolio Segment [Member] \| Real Estate Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	14,782,000	715,000
With no related allowance recorded, principal balance	14,593,000	667,000
With no related allowance recorded, average recorded principal balance	5,361,000	1,520,000
With related allowance recorded, unpaid principal balance	763,000	1,078,000
With related allowance recorded, principal balance	734,000	1,078,000
Related allowance	77,000	982,000
With related allowance recorded, average recorded principal balance	578,000	1,672,000
Commercial Portfolio Segment [Member] \| Real Estate Non Owner Occupied Loan [Member]
With no related allowance recorded, unpaid principal balance	341,000	178,000
With no related allowance recorded, principal balance	341,000	178,000
With no related allowance recorded, average recorded principal balance	227,000	131,000
With related allowance recorded, unpaid principal balance	162,000	0
With related allowance recorded, principal balance	162,000	0
Related allowance	8,000	0
With related allowance recorded, average recorded principal balance	100,000	80,000
Commercial Portfolio Segment [Member] \| Real Estate Multi Family and Residential Rental Loan [Member]
With no related allowance recorded, unpaid principal balance	0	29,000
With no related allowance recorded, principal balance	0	9,000
With no related allowance recorded, average recorded principal balance	3,000	44,000
With related allowance recorded, unpaid principal balance	0	0
With related allowance recorded, principal balance	0	0
Related allowance	0	0
With related allowance recorded, average recorded principal balance	0	54,000
Retail Portfolio Segment [Member]
With no related allowance recorded, unpaid principal balance	5,527,000	4,551,000
With no related allowance recorded, principal balance	3,562,000	3,177,000
With no related allowance recorded, average recorded principal balance	3,663,000	3,281,000
With related allowance recorded, unpaid principal balance	998,000	860,000
With related allowance recorded, principal balance	981,000	841,000
Related allowance	413,000	439,000
With related allowance recorded, average recorded principal balance	1,016,000	1,318,000
Total unpaid principal balance	6,525,000	5,411,000
Total principal balance	4,543,000	4,018,000
Total average recorded principal balance	4,679,000	4,599,000
Retail Portfolio Segment [Member] \| Home Equity and Other [Member]
With no related allowance recorded, unpaid principal balance	1,072,000	1,279,000
With no related allowance recorded, principal balance	987,000	1,209,000
With no related allowance recorded, average recorded principal balance	1,216,000	1,203,000
With related allowance recorded, unpaid principal balance	300,000	502,000
With related allowance recorded, principal balance	283,000	485,000
Related allowance	241,000	356,000
With related allowance recorded, average recorded principal balance	421,000	658,000
Retail Portfolio Segment [Member] \| One to Four Family Mortgages [Member]
With no related allowance recorded, unpaid principal balance	4,455,000	3,272,000
With no related allowance recorded, principal balance	2,575,000	1,968,000
With no related allowance recorded, average recorded principal balance	2,447,000	2,078,000
With related allowance recorded, unpaid principal balance	698,000	358,000
With related allowance recorded, principal balance	698,000	356,000
Related allowance	172,000	83,000
With related allowance recorded, average recorded principal balance	$ 595,000	$ 660,000

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

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