Note 5 - Fair Value Measurements - Additional Quantitative Information About Assets Measured at Fair Value on Non-recurring Basis (Details) - Fair Value, Nonrecurring [Member] - Fair Value, Inputs, Level 3 [Member] - Appraisal of Collateral [Member] $ in Thousands		Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Impaired loans, fair value estimate	[1]	$ 4,566	$ 5,166
Minimum [Member] | Measurement Input, Discount Rate [Member]
Impaired loans, discount rate	[2]	0.354	0.403
Maximum [Member] | Measurement Input, Discount Rate [Member]
Impaired loans, discount rate	[2]	0.495	0.474
Weighted Average [Member] | Measurement Input, Discount Rate [Member]
Impaired loans, discount rate	[2]	0.362	0.418

[1] Fair value is generally determined through independent appraisals of the underlying collateral, which generally include various level III inputs which are not identifiable, less any associated allowance.

[2] Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated liquidation expenses. The range and weighted average of liquidation expenses and other appraisal adjustments are presented as a percent of the appraisal.