Note 16 - Fair Values - Qualitative Information About Level Three Fair Value Measurements for Financial Instruments Measured at Fair Value on Non-recurring Basis (Details) - Fair Value, Measurements, Nonrecurring [Member] $ in Thousands	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Valuation, Cost Approach [Member] | Commercial Real Estate Property [Member
Other real estate owned, fair value	$ 3,485	$ 4,409
Valuation, Cost Approach [Member] | Minimum [Member] | Measurement Input, Comparability Adjustment [Member] | Commercial Real Estate Property [Member
Other real estate owned, measurement input	0	0
Valuation, Cost Approach [Member] | Maximum [Member] | Measurement Input, Comparability Adjustment [Member] | Commercial Real Estate Property [Member
Other real estate owned, measurement input	0.35	0.35
Valuation, Cost Approach [Member] | Weighted Average [Member] | Measurement Input, Comparability Adjustment [Member] | Commercial Real Estate Property [Member
Other real estate owned, measurement input	0.18	0.18
Valuation, Income Approach [Member] | Measurement Input, Discount Rate or Cap Rate [Member] | Commercial Real Estate Property [Member
Other real estate owned, measurement input	0.25	0.25
Valuation, Income Approach [Member] | Minimum [Member] | Measurement Input, Discount Rate or Cap Rate [Member] | Commercial Real Estate Property [Member
Other real estate owned, measurement input	0.25	0.25
Valuation, Income Approach [Member] | Maximum [Member] | Measurement Input, Discount Rate or Cap Rate [Member] | Commercial Real Estate Property [Member
Other real estate owned, measurement input	0.25	0.25
Valuation, Income Approach [Member] | Weighted Average [Member] | Measurement Input, Discount Rate or Cap Rate [Member] | Commercial Real Estate Property [Member
Other real estate owned, measurement input	0.25	0.25
Residential Portfolio Segment [Member] | Valuation, Cost Approach [Member]
Impaired loans, fair value	$ 552	$ 957
Residential Portfolio Segment [Member] | Valuation, Cost Approach [Member] | Minimum [Member] | Measurement Input, Comparability Adjustment [Member]
Impaired loans, measurement input	0	0
Residential Portfolio Segment [Member] | Valuation, Cost Approach [Member] | Maximum [Member] | Measurement Input, Comparability Adjustment [Member]
Impaired loans, measurement input	0.26	0.26
Residential Portfolio Segment [Member] | Valuation, Cost Approach [Member] | Weighted Average [Member] | Measurement Input, Comparability Adjustment [Member]
Impaired loans, measurement input	0.11	0.09