Note 8 - Fair Value of Financial Instruments - Assets and Liabilities Measured On a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Securities available for sale	$ 243,585	$ 179,148
Fair Value, Inputs, Level 1 [Member]
Securities available for sale
Fair Value, Inputs, Level 2 [Member]
Securities available for sale	235,551	170,486
Fair Value, Inputs, Level 3 [Member]
Securities available for sale	8,034	8,662
US Government Agencies Debt Securities [Member]
Securities available for sale	11,352	8,953
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available for sale
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available for sale	11,352	8,953
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available for sale
Corporate Debt Securities [Member]
Securities available for sale	12,889	13,041
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available for sale
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available for sale	12,889	13,041
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available for sale
Collateralized Mortgage Backed Securities [Member]
Securities available for sale	130,301	79,941
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available for sale
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available for sale	130,301	79,941
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available for sale
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale	88,323	76,479
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available for sale
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available for sale	80,289	67,817
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available for sale	8,034	8,662
Other Debt Obligations [Member]
Securities available for sale	720	734
Other Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available for sale
Other Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available for sale	720	734
Other Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available for sale