Note 8 - Loans and Related Allowance for Loan and Lease Losses (Details Textual)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Loans and Leases Receivable, Net of Deferred Income, Total	$ 1,010,282,000		$ 1,010,282,000		$ 1,104,085,000
Loans and Leases Receivable, Deferred Income, Total	3,700,000		3,700,000		4,400,000
Financing Receivable, Troubled Debt Restructuring	2,600,000		2,600,000		2,900,000
Financing Receivable, Allowance for Credit Loss, Writeoff			$ 108,000		45,000
Number of Days Past Due (Day)			90 days
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	107,000	$ 112,000	$ 290,000	$ 215,000
Provision for Loan and Lease Losses, Total	0	4,000,000	900,000	7,740,000
Allowance for Loan and Lease Losses, Write-offs	50,000	3,043,000	442,000	3,758,000
Other Real Estate, Ending Balance	$ 7,090,000	$ 7,000,000.0	$ 7,090,000	$ 7,000,000.0	7,387,000
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts	0	0	0	0
Financing Receivable, Modifications, Number of Contracts	0		0
Threshold For Loans Evaluated For Impairment [Member]
Loans and Leases Receivable, before Fees, Gross	$ 750,000		$ 750,000
Threshold For Loans Evaluated For Impairment [Member] | Outside Consultant [Member]
Loans and Leases Receivable, before Fees, Gross	250,000		250,000
Threshold For Loans Evaluated For Impairment [Member] | Criticized Relationships [Member]
Financing Receivable, before Allowance for Credit Loss, Total	150,000		150,000
Provision Fluctuation [Member]
Provision for Loan and Lease Losses, Total				$ 2,200,000
Non-owner occupied Loan [Member]
Provision for Loan and Lease Losses, Total				1,300,000
Commercial And Industrial [Member]
Loans and Leases Receivable, Net of Deferred Income, Total	163,052,000		163,052,000		232,044,000
Provision for Loan and Lease Losses, Total	17,000	$ 385,000	(264,000)	964,000
Allowance for Loan and Lease Losses, Write-offs	(0)	$ 16,000	(0)	$ 185,000
Financing Receivable, Modifications, Number of Contracts		1		3
Commercial Real Estate Portfolio Segment [Member] | Provision Fluctuation [Member]
Allowance for Loan and Lease Losses, Write-offs		$ 3,000,000.0
Commercial Real Estate Portfolio Segment [Member] | Non-owner occupied Loan [Member]
Loans and Leases Receivable, Net of Deferred Income, Total	310,222,000		310,222,000		309,424,000
Provision for Loan and Lease Losses, Total	126,000	3,267,000	1,196,000	$ 4,972,000
Allowance for Loan and Lease Losses, Write-offs	50,000	3,021,000	313,000	3,022,000
Small Business Administration (SBA), CARES Act, Paycheck Protection Program [Member]
Loans and Leases Receivable, Net of Deferred Income, Total	54,200,000		54,200,000
Loans and Leases Receivable, Deferred Income, Total	2,100,000		2,100,000		2,700,000
Small Business Administration (SBA), CARES Act, Paycheck Protection Program [Member] | Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Loss, Ending Balance		$ 423,000		$ 423,000
Small Business Administration (SBA), CARES Act, Paycheck Protection Program [Member] | Commercial And Industrial [Member]
Loans and Leases Receivable, Net of Deferred Income, Total	$ 54,200,000		$ 54,200,000		$ 116,100,000
Financing Receivable, Allowance for Credit Losses, Percentage of Portfolio	0.40%		0.40%
Financing Receivable, Allowance for Credit Loss, Ending Balance	$ 216,000		$ 216,000