Note 8 - Loans - Troubled Debt Restructurings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Troubled debt restructurings, number of contracts	12	4
Troubled debt restructurings, post-modification recorded investment	$ 1,811	$ 162
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Senior Lien [Member] | Monthly Payment Reduction and Extended Maturity Date [Member]
Troubled debt restructurings, number of contracts	1	0
Troubled debt restructurings, post-modification recorded investment	$ 271	$ 0
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Senior Lien [Member] | Monthly Payment Reduction for 6 Months [Member]
Troubled debt restructurings, number of contracts	0	1
Troubled debt restructurings, post-modification recorded investment	$ 0	$ 80
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Junior Lien [Member] | Monthly Payment Reduction and Extended Maturity Date [Member]
Troubled debt restructurings, number of contracts	1	0
Troubled debt restructurings, post-modification recorded investment	$ 18	$ 0
Residential Portfolio Segment [Member] | Commercial Construction and Land [Member] | Extended Interest Payments and Reduced Monthly Payments with Balloon Payment at Maturity [Member]
Troubled debt restructurings, post-modification recorded investment		$ 0
Commercial Portfolio Segment [Member] | Real Estate Loan [Member] | Senior Lien [Member] | Extended Interest Payments for 6 Months [Member]
Troubled debt restructurings, number of contracts	0	2
Troubled debt restructurings, post-modification recorded investment	$ 0	$ 36
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Monthly Payment Reduction and Extended Maturity Date [Member]
Troubled debt restructurings, number of contracts	8	0
Troubled debt restructurings, post-modification recorded investment	$ 177	$ 0
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member] | Extended Interest Payments for 6 Months [Member]
Troubled debt restructurings, number of contracts	0	1
Troubled debt restructurings, post-modification recorded investment	$ 0	$ 46
Commercial Portfolio Segment [Member] | Commercial Construction and Land [Member] | Extended Interest Payments and Reduced Monthly Payments with Balloon Payment at Maturity [Member]
Troubled debt restructurings, number of contracts	1
Troubled debt restructurings, post-modification recorded investment	$ 1,261
Commercial Portfolio Segment [Member] | Agricultural Loans [Member] | Monthly Payment Reduction and Extended Maturity Date [Member]
Troubled debt restructurings, number of contracts	1	0
Troubled debt restructurings, post-modification recorded investment	$ 84	$ 0
Consumer Portfolio Segment [Member] | Commercial Construction and Land [Member] | Extended Interest Payments and Reduced Monthly Payments with Balloon Payment at Maturity [Member]
Troubled debt restructurings, number of contracts		0