Note 8 - Loans - Impaired Loans and Related Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans with no related allowance, unpaid principal balance	$ 108,485	$ 91,430
Loans with no related allowance, recorded investment	98,612	83,217
Loans with related allowance, unpaid principal balance	39,885	35,646
Loans with related allowance, recorded investment	38,602	34,136
Allowance	3,833	2,134
Total impaired loans, unpaid principal balance	148,370	127,076
Total impaired loans, recorded investment	137,214	117,353
Commercial Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	51,143	43,483
Loans with no related allowance, recorded investment	49,521	42,702
Loans with related allowance, unpaid principal balance	3,247	891
Loans with related allowance, recorded investment	3,218	793
Allowance	2,463	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	8,040	8,185
Commercial Real Estate Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	41,970	37,825
Loans with no related allowance, recorded investment	34,508	31,029
Loans with related allowance, unpaid principal balance	27,495	21,733
Loans with related allowance, recorded investment	27,445	21,635
Allowance	1,036	1,738
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	6,551	1,301
Loans with no related allowance, recorded investment	6,543	1,301
Loans with related allowance, unpaid principal balance	9,143	13,022
Loans with related allowance, recorded investment	7,939	11,708
Allowance	$ 334	$ 353