Note 4 - Loans - Average Recorded Investment and Interest Income Recognized on Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Average recorded investment	$ 11,359	$ 18,647	$ 10,666	$ 18,900
Interest income recognized	52	61	148	209
Commercial Portfolio Segment [Member]
Average recorded investment	1,078	807	777	1,377
Interest income recognized	15	10	32	42
Commercial Real Estate Portfolio Segment [Member] | Commercial Non-owner Occupied [Member]
Average recorded investment	1,062	10,887	590	10,307
Interest income recognized	0	7	0	30
Commercial Real Estate Portfolio Segment [Member] | Commercial Owner Occupied Loan [Member]
Average recorded investment	3,682	0	3,356	0
Interest income recognized	0	0	0	0
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Individual Tax Identification Number Loan [Member]
Average recorded investment	5,241	6,490	5,546	6,694
Interest income recognized	35	40	106	123
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Average recorded investment	146	204	171	194
Interest income recognized	0	0	0	0
Residential Portfolio Segment [Member] | Home Equity Loan [Member]
Average recorded investment	132	238	194	306
Interest income recognized	2	4	10	14
Consumer Portfolio Segment [Member]
Average recorded investment	18	21	32	22
Interest income recognized	$ 0	$ 0	$ 0	$ 0