Note 15 - Fair Value Measurements and Fair Values of Financial Instruments - Assets Measured on a Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Impaired loans	$ 7,322	$ 9,110
Other real estate owned	5,727	8,563
Fair Value, Inputs, Level 1 [Member]
Impaired loans
Other real estate owned
Fair Value, Inputs, Level 2 [Member]
Impaired loans
Other real estate owned
Fair Value, Inputs, Level 3 [Member]
Impaired loans	7,322	9,110
Other real estate owned	$ 5,727	$ 8,563