Note 4 - Loans - Average Recorded Investment and Interest Income Recognized on Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Average recorded investment	$ 10,006	$ 10,153
Interest income recognized	41	50
Commercial Portfolio Segment [Member]
Average recorded investment	2,020	640
Interest income recognized	7	9
Commercial Real Estate Portfolio Segment [Member] | Commercial Non-owner Occupied [Member]
Average recorded investment	632	0
Interest income recognized	0	0
Commercial Real Estate Portfolio Segment [Member] | Commercial Owner Occupied Loan [Member]
Average recorded investment	2,092	3,103
Interest income recognized	0	0
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Individual Tax Identification Number Loan [Member]
Average recorded investment	4,983	5,957
Interest income recognized	32	37
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Average recorded investment	139	186
Interest income recognized	0	0
Residential Portfolio Segment [Member] | Home Equity Loan [Member]
Average recorded investment	123	228
Interest income recognized	2	4
Consumer Portfolio Segment [Member]
Average recorded investment	17	39
Interest income recognized	$ 0	$ 0