Note 4 - Loans and Allowance for Loan Losses - Nonaccrual Loans and Loans Past Due 90 Days or More and Still Accruing (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans past due 90 days and still accruing	$ 471	$ 334
Nonaccrual	10,844	10,112
Residential Portfolio Segment [Member]
Loans past due 90 days and still accruing	188	131
Nonaccrual	6,983	5,906
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Loans past due 90 days and still accruing
Nonaccrual	641	476
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Loans past due 90 days and still accruing
Nonaccrual	1,977	2,454
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans past due 90 days and still accruing
Nonaccrual	397	444
Commercial and Industrial Portfolio Segment [Member]
Loans past due 90 days and still accruing	21
Nonaccrual	386	337
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans past due 90 days and still accruing	135	127
Nonaccrual	67	86
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans past due 90 days and still accruing
Nonaccrual	295	283
Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans past due 90 days and still accruing	127	76
Nonaccrual	$ 98	$ 126