Note 9 - Fair Value of Assets and Liabilities - Quantitative Information about the Level 3 Significant Inputs (Details) $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Impaired loans	$ 233	$ 405
Valuation Technique, Appraisal of Collateral [Member] | Measurement Input, Appraisal Adjustments [Member]
Range of Inputs	(0.76)	(0.76)
Valuation Technique, Appraisal of Collateral [Member] | Measurement Input, Liquidation Expenses [Member]
Range of Inputs	(0.10)	(0.10)