Note 10 - Fair Values - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - Fair Value, Nonrecurring [Member] - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Impaired loans	$ 3,227,000	$ 1,107,000
Foreclosed assets	512,000	452,000
Total	3,739,000	1,559,000
Fair Value, Inputs, Level 1 [Member]
Impaired loans	0	0
Foreclosed assets	0	0
Total	0	0
Fair Value, Inputs, Level 2 [Member]
Impaired loans	0	0
Foreclosed assets	0	0
Total	0	0
Fair Value, Inputs, Level 3 [Member]
Impaired loans	3,227,000	1,107,000
Foreclosed assets	512,000	452,000
Total	$ 3,739,000	$ 1,559,000