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