Note 4 - Loans (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total	$ 1,200		$ 1,200		$ 1,500
Financing Receivable, Number of Payment Deferrals	244		244
Financing Receivable, Deferred Payments	$ 123,300		$ 123,300
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	84	$ 229	140	$ 376
Impaired Financing Receivable, Recorded Investment, Total	$ 11,126		$ 11,126		10,399
Percentage of Collateral Coverage to Loan Balance to Consider Restructured Loan to Performing and Accrual Status			100.00%
Financing Receivable, Modifications, Number of Contracts	1	2	1
Financing Receivable, Troubled Debt Restructuring	$ 6,600		$ 6,600		$ 6,500
Financing Receivable, Number of Contracts Qualified as Troubled Debt Restructuring	97		97
Troubled Debt Restructurings Percentage of Gross Portfolio Loans	0.55%		0.55%		0.63%
Troubled Debt Restructurings Percentage of Gross Portfolio Loans, Excluding PPP Loans	0.64%		0.64%
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts	0
Mortgage Loans in Process of Foreclosure, Amount	$ 83		$ 83		$ 100
Percentage of Unallocated Allowance Amount out of Allowance for Loan and Lease Losses			4.00%		3.00%
Loans and Leases Receivable, Allowance, Ending Balance	$ 16,089		$ 16,089		$ 12,231
Percentage of Allowance for Loan and Lease Losses out of Net Loans	1.33%		1.33%		1.18%
Percentage of Allowance for Loan and Lease Losses out of Net Loans, Excluding PPP Loans	1.54%		1.54%
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Asset	$ 281,200		$ 281,200		$ 275,100
Reserve for Unfunded Commitments Included in Other Liabilities	800		800		695
Loans and Leases Receivable, Gross, Total	$ 1,206,340		$ 1,206,340		1,032,903
Maximum Loan to Value, Percentage			80.00%
Percentage of Loan Portfolio Secured by Real Estate	75.00%		75.00%
Percentage of Loan Portfolio Secured by Real Estate, Excluding PPP Loans	85.00%		85.00%
Commercial Real Estate Portfolio Segment [Member]
Impaired Financing Receivable, Recorded Investment, Total	$ 4,709		$ 4,709		3,103
Financing Receivable, Modifications, Number of Contracts			1
Financing Receivable, Troubled Debt Restructuring	654		$ 654
Loans and Leases Receivable, Gross, Total	778,174		778,174		739,583
SBA CARES Act Paycheck Protection Program [Member]
Loans and Leases Receivable, Gross, Total	$ 162,189		$ 162,189		0
Number of Customers Participated in PPP	594		594
Performing Financial Instruments [Member]
Impaired Financing Receivable, Recorded Investment, Total	$ 4,500		$ 4,500		4,800
Financing Receivable, Number of Contracts Qualified as Troubled Debt Restructuring	95		95
Loans and Leases Receivable, Gross, Total	$ 1,199,669		$ 1,199,669		1,027,287
Performing Financial Instruments [Member] | SBA CARES Act Paycheck Protection Program [Member]
Loans and Leases Receivable, Gross, Total	162,189		162,189
Merchants Holding Company [Member]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total	1,300		1,300		1,700
Accretion (Amortization) of Discounts and Premiums, Acquired Loans	216	$ 190	379	$ 238
Federal Home Loan Bank of San Francisco [Member]
Loans Pledged as Collateral	$ 536,800		$ 536,800		$ 542,100