Note 5 - Modified Loans by Major Loan Class and Total Deferral by Number of Months (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	$ 5,312	$ 5,891
COVID-19 Pandemic [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	33,870
COVID-19 Pandemic [Member] | Total Number of Months Deferred 0-3 Months [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	574
COVID-19 Pandemic [Member] | Total Number of Months Deferred 4-6 Months [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	444
COVID-19 Pandemic [Member] | Total Number of Months Deferred 7-9 Months [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	19,252
COVID-19 Pandemic [Member] | Total Number of Months Deferred 10+ Months [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	13,600
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	1,758
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Secured by Commercial Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	28,814
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Secured by Residential Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	423
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Total Number of Months Deferred 0-3 Months [Member] | Commercial and Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	535
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Total Number of Months Deferred 4-6 Months [Member] | Commercial and Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	33
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Total Number of Months Deferred 7-9 Months [Member] | Commercial and Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	1,190
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Total Number of Months Deferred 7-9 Months [Member] | Secured by Commercial Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	17,485
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Total Number of Months Deferred 7-9 Months [Member] | Secured by Residential Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	423
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Total Number of Months Deferred 10+ Months [Member] | Secured by Commercial Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	11,329
COVID-19 Pandemic [Member] | State and Political Subdivisions Portfolio Segment [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	152
COVID-19 Pandemic [Member] | State and Political Subdivisions Portfolio Segment [Member] | Total Number of Months Deferred 4-6 Months [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	152
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Consumer Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	4
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Family Residential Mortgages [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	1,895
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Home Equity Loans and Lines [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	824
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Total Number of Months Deferred 0-3 Months [Member] | Home Equity Loans and Lines [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	39
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Total Number of Months Deferred 4-6 Months [Member] | Consumer Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	4
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Total Number of Months Deferred 4-6 Months [Member] | Family Residential Mortgages [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	255
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Total Number of Months Deferred 7-9 Months [Member] | Family Residential Mortgages [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	116
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Total Number of Months Deferred 7-9 Months [Member] | Home Equity Loans and Lines [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	38
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Total Number of Months Deferred 10+ Months [Member] | Family Residential Mortgages [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	1,524
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Total Number of Months Deferred 10+ Months [Member] | Home Equity Loans and Lines [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	$ 747