Note 5 - Fair Value Measurements - Assets Measured on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Impaired loans	$ 15,971	$ 14,075
Fair Value, Nonrecurring [Member]
Impaired loans	4,604	1,075
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	$ 4,604	$ 1,075