Note 7 - Fair Value - Assets Measured at Fair Value on a Non-recurring Basis (Details) - Fair Value, Nonrecurring [Member] - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Other real estate owned	$ 9,000	$ 9,000
Total	406,000	407,000
Fair Value, Inputs, Level 1 [Member]
Other real estate owned
Total
Fair Value, Inputs, Level 2 [Member]
Other real estate owned
Total
Fair Value, Inputs, Level 3 [Member]
Other real estate owned	9,000	9,000
Total	406,000	407,000
Commercial Portfolio Segment [Member]
Impaired loans	58,000	58,000
Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member]
Impaired loans
Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member]
Impaired loans
Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member]
Impaired loans	58,000	58,000
Commercial Real Estate Portfolio Segment [Member]
Impaired loans	339,000	340,000
Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member]
Impaired loans
Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member]
Impaired loans
Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member]
Impaired loans	$ 339,000	$ 340,000