Note 4 - Allowance for Loan Losses and Impaired Loans - Loans Remained in Deferment Status (Details) $ in Thousands	Sep. 30, 2021 USD ($)	Dec. 13, 2020 USD ($)
Balance	$ 404	$ 9,009
Number of loans	1	18
Customer Loans With First Deferment Portfolio Segment [Member]
Balance	$ 0	$ 782
Number of loans		7
Customer Loans With Second Deferment Portfolio Segment [Member]
Balance	0	$ 52
Number of loans		1
Accommodation and Retail Services [Member] | Commercial Loans With First Deferment Portfolio Segment [Member]
Balance	0	$ 0
Accommodation and Retail Services [Member] | Commercial Loans With Second Deferment Portfolio Segment [Member]
Balance	0	$ 752
Number of loans		1
Accommodation and Retail Services [Member] | Commercial Loans With Third Deferment Portfolio Segment [Member]
Balance	0	$ 4,438
Number of loans		2
Construction Loans [Member] | Commercial Loans With First Deferment Portfolio Segment [Member]
Balance	0	$ 47
Number of loans		1
General and Other [Member] | Commercial Loans With First Deferment Portfolio Segment [Member]
Balance	0	$ 0
General and Other [Member] | Commercial Loans With Second Deferment Portfolio Segment [Member]
Balance	$ 404	0
Number of loans	1
Construction Industry [Member] | Commercial Loans With Second Deferment Portfolio Segment [Member]
Balance	$ 0	$ 36
Number of loans		1
Construction Industry [Member] | Commercial Loans With Third Deferment Portfolio Segment [Member]
Balance	0	$ 0
Agricultural [Member] | Commercial Loans With First Deferment Portfolio Segment [Member]
Balance	0	$ 603
Number of loans		2
Commercial Real Estate [Member] | Commercial Loans With Second Deferment Portfolio Segment [Member]
Balance	0	$ 2,146
Number of loans		2
Manufacturing [Member] | Commercial Loans With Third Deferment Portfolio Segment [Member]
Balance	$ 0	$ 153
Number of loans		1