Note 4 - Loans - Types of Modifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Financing receivable, modifications	$ 85	$ 95	$ 7,243	$ 95
Extended Maturity [Member]
Financing receivable, modifications	0	0	63	0
Extended Maturity and Capitalization of Taxes [Member]
Financing receivable, modifications	85	95	85	95
Extended Maturity and Forbearance [Member]
Financing receivable, modifications	0	0	25	0
Forbearance [Member]
Financing receivable, modifications	0	0	7,070	0
Residential Portfolio Segment [Member]
Financing receivable, modifications	0	95	63	95
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Financing receivable, modifications	0	0	63	0
Residential Portfolio Segment [Member] | Extended Maturity and Capitalization of Taxes [Member]
Financing receivable, modifications	0	95	0	95
Residential Portfolio Segment [Member] | Extended Maturity and Forbearance [Member]
Financing receivable, modifications	0	0	0	0
Residential Portfolio Segment [Member] | Forbearance [Member]
Financing receivable, modifications	0	0	0	0
Commercial Real Estate Portfolio Segment [Member]
Financing receivable, modifications	0	0	5,250	0
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member]
Financing receivable, modifications	0	0	0	0
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity and Capitalization of Taxes [Member]
Financing receivable, modifications	0	0	0	0
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity and Forbearance [Member]
Financing receivable, modifications	0	0	0	0
Commercial Real Estate Portfolio Segment [Member] | Forbearance [Member]
Financing receivable, modifications	0	0	5,250	0
Construction, Land Acquisition and Development [Member]
Financing receivable, modifications	0	0	0	0
Construction, Land Acquisition and Development [Member] | Extended Maturity [Member]
Financing receivable, modifications	0	0	0	0
Construction, Land Acquisition and Development [Member] | Extended Maturity and Capitalization of Taxes [Member]
Financing receivable, modifications	0	0	0	0
Construction, Land Acquisition and Development [Member] | Extended Maturity and Forbearance [Member]
Financing receivable, modifications	0	0	0	0
Construction, Land Acquisition and Development [Member] | Forbearance [Member]
Financing receivable, modifications	0	0	0	0
Commercial and Industrial [Member]
Financing receivable, modifications	0	0	1,845	0
Commercial and Industrial [Member] | Extended Maturity [Member]
Financing receivable, modifications	0	0	0	0
Commercial and Industrial [Member] | Extended Maturity and Capitalization of Taxes [Member]
Financing receivable, modifications	0	0	0	0
Commercial and Industrial [Member] | Extended Maturity and Forbearance [Member]
Financing receivable, modifications	0	0	25	0
Commercial and Industrial [Member] | Forbearance [Member]
Financing receivable, modifications	0	0	1,820	0
Consumer Portfolio Segment [Member]
Financing receivable, modifications	85	0	85	0
Consumer Portfolio Segment [Member] | Extended Maturity [Member]
Financing receivable, modifications	0	0	0	0
Consumer Portfolio Segment [Member] | Extended Maturity and Capitalization of Taxes [Member]
Financing receivable, modifications	85	0	85	0
Consumer Portfolio Segment [Member] | Extended Maturity and Forbearance [Member]
Financing receivable, modifications	0	0	0	0
Consumer Portfolio Segment [Member] | Forbearance [Member]
Financing receivable, modifications	0	0	0	0
State and Political Subdivisions [Member]
Financing receivable, modifications	0	0	0	0
State and Political Subdivisions [Member] | Extended Maturity [Member]
Financing receivable, modifications	0	0	0	0
State and Political Subdivisions [Member] | Extended Maturity and Capitalization of Taxes [Member]
Financing receivable, modifications	0	0	0	0
State and Political Subdivisions [Member] | Extended Maturity and Forbearance [Member]
Financing receivable, modifications	0	0	0	0
State and Political Subdivisions [Member] | Forbearance [Member]
Financing receivable, modifications	$ 0	$ 0	$ 0	$ 0