Note 5 - Loans and the Allowance for Loan Losses - Credit Risk Profile by Internally Assigned Grade (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Loans	$ 619,718,000	$ 566,199,000
Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans	94,687,000	80,805,000
Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans	186,000	410,000
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans	90,310,000	77,135,000
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Performing Financial Instruments [Member]
Loans	90,128,000	76,734,000
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Nonperforming Financial Instruments [Member]
Loans	182,000	401,000
Consumer Portfolio Segment [Member] | Other Loans [Member]
Loans	4,563,000	4,080,000
Consumer Portfolio Segment [Member] | Other Loans [Member] | Performing Financial Instruments [Member]
Loans	4,559,000	4,071,000
Consumer Portfolio Segment [Member] | Other Loans [Member] | Nonperforming Financial Instruments [Member]
Loans	4,000	9,000
Consumer Portfolio Segment [Member] | Residential Portfolio Segment [Member]
Loans	$ 94,873,000
Consumer Portfolio Segment [Member] | Commercial Portfolio Segment [Member]
Loans		$ 81,215,000