Note 3 - Loans - Aging of the Recorded Investment in Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current	$ 2,323,069	$ 2,295,871
Past due	12,051	9,504
Loans	2,335,120	2,305,375
Recorded investment greater than 90 days and accruing	261	438
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	5,673	2,589
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	1,259	1,182
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	5,119	5,733
Commercial and Industrial Portfolio Segment [Member]
Current	747,316	734,682
Past due	3,412	2,159
Loans	750,728	736,841
Recorded investment greater than 90 days and accruing		18
Commercial and Industrial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	2,149	84
Commercial and Industrial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	7	290
Commercial and Industrial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	1,256	1,785
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Current	173,573	191,810
Past due	737	538
Loans	174,310	192,348
Recorded investment greater than 90 days and accruing
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	737	538
Undevelopment Land Portfolio Segment [Member]
Current	20,515	21,022
Past due	474	474
Loans	20,989	21,496
Recorded investment greater than 90 days and accruing
Undevelopment Land Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due
Undevelopment Land Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due
Undevelopment Land Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	474	474
Real Estate Mortgage Portfolio Segment [Member]
Current	1,344,469	1,313,392
Past due	7,193	6,128
Loans	1,351,662	1,319,520
Recorded investment greater than 90 days and accruing	261	420
Real Estate Mortgage Portfolio Segment [Member] | Commercial Investment [Member]
Current	574,088	537,998
Past due	2,722	888
Loans	576,810	538,886
Recorded investment greater than 90 days and accruing		86
Real Estate Mortgage Portfolio Segment [Member] | Owner Occupied Commercial [Member]
Current	395,924	406,726
Past due	1,880	1,566
Loans	397,804	408,292
Recorded investment greater than 90 days and accruing		182
Real Estate Mortgage Portfolio Segment [Member] | One to Four Family Residential [Member]
Current	259,729	246,730
Past due	1,978	2,768
Loans	261,707	249,498
Recorded investment greater than 90 days and accruing	261	34
Real Estate Mortgage Portfolio Segment [Member] | Home Equity First Lien [Member]
Current	51,836	55,027
Past due	89	298
Loans	51,925	55,325
Recorded investment greater than 90 days and accruing		46
Real Estate Mortgage Portfolio Segment [Member] | Home Equity Junior Lien [Member]
Current	62,892	66,911
Past due	524	608
Loans	63,416	67,519
Recorded investment greater than 90 days and accruing		72
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	3,298	2,477
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Investment [Member]
Past due	2,667	631
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Owner Occupied Commercial [Member]
Past due	47	342
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | One to Four Family Residential [Member]
Past due	330	1,174
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity First Lien [Member]
Past due	89	231
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity Junior Lien [Member]
Past due	165	99
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	1,243	787
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Investment [Member]
Past due		64
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Owner Occupied Commercial [Member]
Past due	363
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | One to Four Family Residential [Member]
Past due	602	576
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity First Lien [Member]
Past due		21
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity Junior Lien [Member]
Past due	278	126
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	2,652	2,864
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Investment [Member]
Past due	55	193
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Owner Occupied Commercial [Member]
Past due	1,470	1,224
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | One to Four Family Residential [Member]
Past due	1,046	1,018
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity First Lien [Member]
Past due		46
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity Junior Lien [Member]
Past due	81	383
Consumer Portfolio Segment [Member]
Current	37,196	34,965
Past due	235	205
Loans	37,431	35,170
Recorded investment greater than 90 days and accruing
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	226	28
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	9	105
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		$ 72