Note 9 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Assets Measured on Non-recurring Basis (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Impaired loans, fair value	$ 2,378	$ 2,224
Foreclosed assets held for sale, fair value
Fair Value, Inputs, Level 1 [Member]
Impaired loans, fair value
Foreclosed assets held for sale, fair value
Fair Value, Inputs, Level 2 [Member]
Impaired loans, fair value
Foreclosed assets held for sale, fair value
Fair Value, Inputs, Level 3 [Member]
Impaired loans, fair value	2,378	2,224
Foreclosed assets held for sale, fair value