Note 4 - Loans and Allowance for Loan Losses - Recorded Investment of Residential and Consumer Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans receivable	$ 768,065	$ 769,319
Consumer Portfolio Segment [Member]
Loans receivable	137,621	139,621
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans receivable	67,752	68,626
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans receivable	21,598	21,431
Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans receivable	48,271	49,564
Residential Portfolio Segment [Member]
Loans receivable	305,193	309,163
Consumer and Residential Portfolio Segment [Member]
Loans receivable	442,814	448,784
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans receivable	67,539	68,413
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans receivable	21,338	21,148
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans receivable	48,069	49,362
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member]
Loans receivable	297,278	303,126
Performing Financial Instruments [Member] | Consumer and Residential Portfolio Segment [Member]
Loans receivable	434,224	442,049
Nonperforming Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Loans receivable	213	213
Nonperforming Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Loans receivable	260	283
Nonperforming Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Other Consumer Loans [Member]
Loans receivable	202	202
Nonperforming Financial Instruments [Member] | Residential Portfolio Segment [Member]
Loans receivable	7,915	6,037
Nonperforming Financial Instruments [Member] | Consumer and Residential Portfolio Segment [Member]
Loans receivable	$ 8,590	$ 6,735