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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Average recorded investment	$ 18,647	$ 10,829	$ 18,900	$ 11,261
Interest income recognized	61	78	209	236
Commercial Portfolio Segment [Member]
Average recorded investment	807	2,254	1,377	2,508
Interest income recognized	10	19	42	60
Commercial Real Estate Portfolio Segment [Member] | Commercial Non-owner Occupied [Member]
Average recorded investment	10,887	798	10,307	799
Interest income recognized	7	11	30	35
Residential Portfolio Segment [Member] | Individual Tax Identification Number Loan [Member]
Average recorded investment	6,490	7,154	6,694	7,272
Interest income recognized	40	43	123	126
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Average recorded investment	204	181	194	231
Interest income recognized
Residential Portfolio Segment [Member] | Home Equity Loan [Member]
Average recorded investment	238	412	306	418
Interest income recognized	4	5	14	15
Consumer Portfolio Segment [Member]
Average recorded investment	21	30	22	33
Interest income recognized