Note 4 - Loans - Average Balance and Interest Income by Loan Category Recognized on Impaired Loans (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Average Balance		$ 12,978	$ 10,979
Interest Income	[1]	104	103
Residential Portfolio Segment [Member] | Real Estate Loan [Member]
Average Balance		1,839	1,868
Interest Income	[1]	21	21
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Average Balance		9,630	7,839
Interest Income	[1]	77	77
Construction, Land Acquisition and Development [Member] | Real Estate Loan [Member]
Average Balance		82	84
Interest Income	[1]	1	1
Commercial and Industrial [Member]
Average Balance		1,047	795
Interest Income	[1]
Consumer Portfolio Segment [Member]
Average Balance		380	393
Interest Income	[1]	5	4
State and Political Subdivisions [Member]
Average Balance		0	0
Interest Income	[1]	$ 0	$ 0

[1] Interest income represents income recognized on performing TDRs.