Note 5 - Fair Value Measurements - Assets Measured on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Impaired loans	$ 12,886	$ 13,070
Fair Value, Nonrecurring [Member]
Impaired loans	4,566	5,166
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Impaired loans
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Impaired loans	$ 4,566	$ 5,166