Note 5 - Loans - Average Recorded Investment and Interest Income Recognized on Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Average recorded investment	$ 11,207	$ 15,585	$ 18,323
Interest income recognized	314	275	286
Commercial Portfolio Segment [Member]
Average recorded investment	2,455	3,211	2,605
Interest income recognized	78	46	23
Commercial Portfolio Segment [Member] | Commercial Owner Occupied Loan [Member]
Interest income recognized
Commercial Real Estate Portfolio Segment [Member] | Commercial Non-owner Occupied [Member]
Average recorded investment	890	1,548	2,013
Interest income recognized	46	46	47
Commercial Real Estate Portfolio Segment [Member] | Commercial Owner Occupied Loan [Member]
Average recorded investment		670	1,281
Interest income recognized		2	25
Residential Portfolio Segment [Member] | Individual Tax Identification Number Loan [Member]
Average recorded investment	7,198	7,961	8,939
Interest income recognized	170	162	165
Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Mortgage Receivable [Member]
Average recorded investment	218	1,019	1,788
Interest income recognized
Residential Portfolio Segment [Member] | Home Equity Loan [Member]
Average recorded investment	415	1,104	1,535
Interest income recognized	20	19	26
Consumer Portfolio Segment [Member]
Average recorded investment	31	72	162
Interest income recognized