Note 8 - Loans - Impaired Loans and Related Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans with no related allowance, unpaid principal balance	$ 105,382	$ 91,430
Loans with no related allowance, recorded investment	96,641	83,217
Loans with related allowance, unpaid principal balance	36,664	35,646
Loans with related allowance, recorded investment	35,472	34,136
Allowance	1,502	2,134
Total impaired loans, unpaid principal balance	142,046	127,076
Total impaired loans, recorded investment	132,113	117,353
Commercial Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	45,698	43,483
Loans with no related allowance, recorded investment	44,680	42,702
Loans with related allowance, unpaid principal balance	258	891
Loans with related allowance, recorded investment	231	793
Allowance	11	43
Real Estate Construction Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	8,821	8,821
Loans with no related allowance, recorded investment	8,113	8,185
Commercial Real Estate Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	44,486	37,825
Loans with no related allowance, recorded investment	37,471	31,029
Loans with related allowance, unpaid principal balance	27,315	21,733
Loans with related allowance, recorded investment	27,276	21,635
Allowance	1,145	1,738
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	6,377	1,301
Loans with no related allowance, recorded investment	6,377	1,301
Loans with related allowance, unpaid principal balance	9,091	13,022
Loans with related allowance, recorded investment	7,965	11,708
Allowance	$ 346	$ 353