Note 4 - Loans and Allowance for Loan Losses - Recorded Investment of Residential and Consumer Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans receivable	$ 781,980	$ 769,319
Consumer Portfolio Segment [Member]
Loans receivable	139,289	139,621
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans receivable	68,446	68,626
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans receivable	22,240	21,431
Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans receivable	48,603	49,564
Residential Portfolio Segment [Member]
Loans receivable	305,318	309,163
Consumer and Residential Portfolio Segment [Member]
Loans receivable	444,607	448,784
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans receivable	68,244	68,413
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans receivable	21,945	21,148
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans receivable	48,378	49,362
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member]
Loans receivable	298,147	303,126
Performing Financial Instruments [Member] | Consumer and Residential Portfolio Segment [Member]
Loans receivable	436,714	442,049
Nonperforming Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans receivable	202	213
Nonperforming Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans receivable	295	283
Nonperforming Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans receivable	225	202
Nonperforming Financial Instruments [Member] | Residential Portfolio Segment [Member]
Loans receivable	7,171	6,037
Nonperforming Financial Instruments [Member] | Consumer and Residential Portfolio Segment [Member]
Loans receivable	$ 7,893	$ 6,735