Note 4 - Loans and Allowance for Loan Losses - TDR Loan Modifications (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Troubled Debt Restructuring	$ 9,584	$ 8,634
Residential Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	215	216
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Troubled Debt Restructuring	450
Residential Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring	400
Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	947	968
Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	10	385
Commercial Real Estate Portfolio Segment [Member] | Reduction of Principal and Interest Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	1,559	529
Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		469
Commercial Real Estate Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		402
Commercial Real Estate Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	560
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		362
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	358
Commercial and Industrial Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	4,886	4,742
Commercial and Industrial Portfolio Segment [Member] | Reduction of Principal and Interest Payments [Member]
Troubled Debt Restructuring	199
Commercial and Industrial Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring		561
Performing Financial Instruments [Member]
Troubled Debt Restructuring	9,216	7,887
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	215	216
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member] | Extended Maturity [Member]
Troubled Debt Restructuring	450
Performing Financial Instruments [Member] | Residential Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring	400
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring	947	968
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring
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	1,559	529
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Extended Maturity [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		469
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		402
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	560
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring
Performing Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring
Performing Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Interest Only Payments [Member]
Troubled Debt Restructuring	4,886	4,742
Performing Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Reduction of Principal and Interest Payments [Member]
Troubled Debt Restructuring	199
Performing Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Interest Rate Below Market Reduction [Member]
Troubled Debt Restructuring		561
Nonperforming Financial Instruments [Member]
Troubled Debt Restructuring	368	747
Nonperforming Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Interest Only Payments [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	10	385
Nonperforming Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Owner Occupied [Member]
Troubled Debt Restructuring		$ 362
Nonperforming Financial Instruments [Member] | Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member] | Commercial Real Estate Nonowner Occupied [Member]
Troubled Debt Restructuring	358
Nonperforming Financial Instruments [Member] | Commercial and Industrial Portfolio Segment [Member] | Reduction of Principal and Interest Payments [Member]
Troubled Debt Restructuring