Note 13 - Disclosures About Fair Value of Assets and Liabilities - Fair Value Quantitative Information (Details) - Fair Value, Inputs, Level 3 [Member] - Valuation, Market Approach [Member] $ in Thousands	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Impaired loans (collateral dependent)	$ 1,418	$ 5,809
Foreclosed assets held for sale	$ 0	$ 371
Minimum [Member]
Impaired loans (collateral dependent)	0	0.01
Foreclosed assets held for sale		0.04
Maximum [Member]
Impaired loans (collateral dependent)	0.80	0.80
Foreclosed assets held for sale	0	0.04
Weighted Average [Member]
Impaired loans (collateral dependent)	(0.16)	(0.07)
Foreclosed assets held for sale	(0)	(0.04)