Note 8 - Modified Loans by Major Loan Class and Total Deferral by Number of Months (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	$ 5,564	$ 5,891
COVID-19 Pandemic [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	66,148
COVID-19 Pandemic [Member] | Total Number of Months Deferred 0-3 Months [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	228
COVID-19 Pandemic [Member] | Total Number of Months Deferred 4-6 Months [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	38,460
COVID-19 Pandemic [Member] | Total Number of Months Deferred 7-9 Months [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	27,460
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	3,445
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Secured by Commercial Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	53,205
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Secured by Residential Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	5,588
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	33
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	3,375
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Total Number of Months Deferred 4-6 Months [Member] | Secured by Commercial Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	28,753
COVID-19 Pandemic [Member] | Commercial Portfolio Segment [Member] | Total Number of Months Deferred 4-6 Months [Member] | Secured by Residential Real Estate [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	5,475
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	37
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	24,452
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	113
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 0-3 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	2,515
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Home Equity Loans and Lines [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	1,239
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Total Number of Months Deferred 0-3 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 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] | Family Residential Mortgages [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	404
COVID-19 Pandemic [Member] | Retail Portfolio Segment [Member] | Total Number of Months Deferred 4-6 Months [Member] | Home Equity Loans and Lines [Member]
Accounts Notes And Loans Receivable [Line Items]
Total Modified Loans	453
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	2,111
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	$ 747