Note 2 - Fair Value of Financial Instruments - Level 3 Fair Value Measurements (Details) - Valuation, Market Approach [Member] $ in Thousands	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Fair Value, Nonrecurring [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member] | Measurement Input, Comparability Adjustment [Member]
Impaired Loans, Fair Value		$ 264
Fair Value, Nonrecurring [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member] | Measurement Input, Comparability Adjustment [Member] | Maximum [Member]
Impaired Loans, Measurement Input		0.667
Fair Value, Nonrecurring [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member] | Measurement Input, Comparability Adjustment [Member] | Weighted Average [Member]
Impaired Loans, Measurement Input		0.18
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member]
Impaired Loans, Fair Value	$ 1,206
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Minimum [Member]
Impaired Loans, Measurement Input	0.002
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Maximum [Member]
Impaired Loans, Measurement Input	0.2
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Residential Portfolio Segment [Member] | Real Estate Loan [Member] | Weighted Average [Member]
Impaired Loans, Measurement Input	0.112
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Impaired Loans, Fair Value	$ 263
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member] | Minimum [Member]
Impaired Loans, Measurement Input	0.068
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member] | Maximum [Member]
Impaired Loans, Measurement Input	0.667
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member] | Weighted Average [Member]
Impaired Loans, Measurement Input	0.18
Fair Value, Recurring [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member] | Measurement Input, Comparability Adjustment [Member] | Minimum [Member]
Impaired Loans, Measurement Input		0.068