Note 4 - Loans and Allowance for Loan Losses - TDR Loan Modifications (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Troubled Debt Restructuring	$ 14,802	$ 16,942
Residential Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	690	697
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Troubled Debt Restructuring	525
Residential Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring	408
Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	997	997
Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	2,505	2,521
Commercial Real Estate Portfolio Segment [Member] | Reduction of Principal and Interest Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	548	554
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		1,466
Commercial Real Estate Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		410
Commercial Real Estate Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	566
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		372
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	371
Commercial and Industrial Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	8,192	9,154
Commercial and Industrial Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring		570
Consumer Portfolio Segment [Member] | Extended Maturity [Member] | Home Equity Loan [Member]
Troubled Debt Restructuring		201
Performing Financial Instruments [Member]
Troubled Debt Restructuring	12,857	14,780
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	690	697
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member] | Extended Maturity [Member]
Troubled Debt Restructuring	525
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring	408
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	997	997
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	560	560
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Reduction of Principal and Interest Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	548	554
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		1,466
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		410
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	566
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		372
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	371
Performing Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	8,192	9,154
Performing Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring		570
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Extended Maturity [Member] | Home Equity Loan [Member]
Troubled Debt Restructuring
Nonperforming Financial Instruments [Member]
Troubled Debt Restructuring	1,945	2,162
Nonperforming Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	$ 1,945	1,961
Nonperforming Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring
Nonperforming Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring
Nonperforming Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Extended Maturity [Member] | Home Equity Loan [Member]
Troubled Debt Restructuring		$ 201