Note 8 - Loans - Impaired Loans and Related Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans with no related allowance, unpaid principal balance	$ 87,269	$ 91,430
Loans with no related allowance, recorded investment	77,166	83,217
Loans with related allowance, unpaid principal balance	41,011	35,646
Loans with related allowance, recorded investment	39,843	34,136
Allowance	3,704	2,134
Total impaired loans, unpaid principal balance	128,280	127,076
Total impaired loans, recorded investment	117,009	117,353
Commercial Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	40,426	43,483
Loans with no related allowance, recorded investment	38,556	42,702
Loans with related allowance, unpaid principal balance	5,792	891
Loans with related allowance, recorded investment	5,715	793
Allowance	2,506	43
Real Estate Construction Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	5,776	8,821
Loans with no related allowance, recorded investment	4,922	8,185
Commercial Real Estate Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	34,276	37,825
Loans with no related allowance, recorded investment	26,912	31,029
Loans with related allowance, unpaid principal balance	27,549	21,733
Loans with related allowance, recorded investment	27,523	21,635
Allowance	917	1,738
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	6,791	1,301
Loans with no related allowance, recorded investment	6,776	1,301
Loans with related allowance, unpaid principal balance	7,670	13,022
Loans with related allowance, recorded investment	6,605	11,708
Allowance	$ 281	$ 353