Note 8 - Deposits - Public Entity Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Collateralized by investment securities	$ 8,440	$ 9,917
U.S. govt. sponsored agency securities
Collateralized by investment securities	3,668	6,135
Residential mortgage-backed and related securities
Collateralized by investment securities	$ 4,772	$ 3,782