Note 9 - Fair Value Accounting and Measurement - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Impaired loans	$ 6,355	$ 6,389
Fair Value, Inputs, Level 1 [Member]
Impaired loans	0	0
Fair Value, Inputs, Level 2 [Member]
Impaired loans	0	0
Fair Value, Inputs, Level 3 [Member]
Impaired loans	$ 6,355	$ 6,389