Note 4 - Loans and Allowance for Loan Losses - TDR Loan Modifications (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Troubled Debt Restructuring	$ 16,845	$ 16,043
Residential Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	702	717
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Troubled Debt Restructuring	230
Residential Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring	412
Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	94	284
Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	2,675	2,810
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	1,497	1,582
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		232
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	375	384
Commercial Real Estate Portfolio Segment [Member] | Reduction of Principal and Interest Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	560	579
Commercial Real Estate Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		574
Commercial Real Estate Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	570
Commercial and Industrial Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	8,752	8,074
Commercial and Industrial Portfolio Segment [Member] | Extended Maturity [Member]
Troubled Debt Restructuring	770
Commercial and Industrial Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring		391
Consumer Portfolio Segment [Member] | Extended Maturity [Member] | Home Equity Loan [Member]
Troubled Debt Restructuring	208	213
Consumer Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Home Equity Loan [Member]
Troubled Debt Restructuring		203
Performing Financial Instruments [Member]
Troubled Debt Restructuring	14,522	13,210
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	702	717
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member] | Extended Maturity [Member]
Troubled Debt Restructuring	230
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring	412
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	94	284
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	560	600
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	1,497	1,582
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	375	384
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	560	579
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		574
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	570
Performing Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	8,752	8,074
Performing Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Extended Maturity [Member]
Troubled Debt Restructuring	770
Performing Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Extended Maturity [Member] | Home Equity Loan [Member]
Troubled Debt Restructuring		213
Performing Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Home Equity Loan [Member]
Troubled Debt Restructuring		203
Nonperforming Financial Instruments [Member]
Troubled Debt Restructuring	2,323	2,833
Nonperforming Financial Instruments [Member] | Residential Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring
Nonperforming Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	2,115	2,210
Nonperforming Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		232
Nonperforming Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring
Nonperforming Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring
Nonperforming Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Extended Maturity [Member]
Troubled Debt Restructuring
Nonperforming Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring		391
Nonperforming Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Extended Maturity [Member] | Home Equity Loan [Member]
Troubled Debt Restructuring	$ 208
Nonperforming Financial Instruments [Member] | Consumer Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Home Equity Loan [Member]
Troubled Debt Restructuring