Note 6 - Core Deposit Intangible Asset, Net (Details Textual) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Core Deposits, Gross	$ 17,500,000	$ 17,500,000
Finite-Lived Intangible Assets, Accumulated Amortization	15,100,000	13,700,000
Finite-Lived Intangible Assets, Net, Ending Balance	$ 2,436,000	$ 3,840,000