Note 4 - Loans - Loans Modified as TDRs (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018	Sep. 30, 2019 USD ($)	Sep. 30, 2018
Number of contracts	3	0	4	0
Pre-modification outstanding recorded investment			$ 274
Post-modification outstanding recorded investment	$ 261		285
Forbearance [Member]
Pre-modification outstanding recorded investment			208
Extended Maturity [Member]
Pre-modification outstanding recorded investment			24
Capitalization of Taxes [Member]
Pre-modification outstanding recorded investment			$ 42
Residential Portfolio Segment [Member]
Number of contracts	3		4
Pre-modification outstanding recorded investment	$ 250		$ 274
Post-modification outstanding recorded investment	261		285
Residential Portfolio Segment [Member] | Forbearance [Member]
Pre-modification outstanding recorded investment	208		208
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Pre-modification outstanding recorded investment	0		24
Residential Portfolio Segment [Member] | Capitalization of Taxes [Member]
Pre-modification outstanding recorded investment	$ 42		$ 42
Commercial Real Estate Portfolio Segment [Member]
Number of contracts	0		0
Pre-modification outstanding recorded investment	$ 0		$ 0
Post-modification outstanding recorded investment	0		0
Commercial Real Estate Portfolio Segment [Member] | Forbearance [Member]
Pre-modification outstanding recorded investment	0		0
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member]
Pre-modification outstanding recorded investment	0		0
Commercial Real Estate Portfolio Segment [Member] | Capitalization of Taxes [Member]
Pre-modification outstanding recorded investment	$ 0		$ 0
Construction, Land Acquisition and Development [Member]
Number of contracts	0		0
Pre-modification outstanding recorded investment	$ 0		$ 0
Post-modification outstanding recorded investment	0		0
Construction, Land Acquisition and Development [Member] | Forbearance [Member]
Pre-modification outstanding recorded investment	0		0
Construction, Land Acquisition and Development [Member] | Extended Maturity [Member]
Pre-modification outstanding recorded investment	0		0
Construction, Land Acquisition and Development [Member] | Capitalization of Taxes [Member]
Pre-modification outstanding recorded investment	$ 0		$ 0
Commercial and Industrial [Member]
Number of contracts	0		0
Pre-modification outstanding recorded investment	$ 0		$ 0
Post-modification outstanding recorded investment	0		0
Commercial and Industrial [Member] | Forbearance [Member]
Pre-modification outstanding recorded investment	0		0
Commercial and Industrial [Member] | Extended Maturity [Member]
Pre-modification outstanding recorded investment	0		0
Commercial and Industrial [Member] | Capitalization of Taxes [Member]
Pre-modification outstanding recorded investment	$ 0		$ 0
Consumer Portfolio Segment [Member]
Number of contracts	0		0
Pre-modification outstanding recorded investment	$ 0		$ 0
Post-modification outstanding recorded investment	0		0
Consumer Portfolio Segment [Member] | Forbearance [Member]
Pre-modification outstanding recorded investment	0		0
Consumer Portfolio Segment [Member] | Extended Maturity [Member]
Pre-modification outstanding recorded investment	0		0
Consumer Portfolio Segment [Member] | Capitalization of Taxes [Member]
Pre-modification outstanding recorded investment	$ 0		$ 0
State and Political Subdivisions [Member]
Number of contracts	0		0
Pre-modification outstanding recorded investment	$ 0		$ 0
Post-modification outstanding recorded investment	0		0
State and Political Subdivisions [Member] | Forbearance [Member]
Pre-modification outstanding recorded investment	0		0
State and Political Subdivisions [Member] | Extended Maturity [Member]
Pre-modification outstanding recorded investment	0		0
State and Political Subdivisions [Member] | Capitalization of Taxes [Member]
Pre-modification outstanding recorded investment	$ 0		$ 0