Note 5 - Loans - Internally Assigned Risk Grades of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans	$ 2,409,570	$ 2,305,375	$ 2,033,007
Commercial and Industrial Portfolio Segment [Member]
Loans	779,014	736,841	644,398
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Loans	195,912	192,348	134,482
Undevelopment Land Portfolio Segment [Member]
Loans	18,988	21,496	21,185
Real Estate Mortgage Portfolio Segment [Member]
Loans	1,376,788	1,319,520	1,197,411
Real Estate Mortgage Portfolio Segment [Member] | Commercial Investment [Member]
Loans	594,902	538,886
Real Estate Mortgage Portfolio Segment [Member] | Owner Occupied Commercial [Member]
Loans	398,685	408,292
Real Estate Mortgage Portfolio Segment [Member] | One to Four Family Residential [Member]
Loans	262,110	249,498
Real Estate Mortgage Portfolio Segment [Member] | Home Equity First Lien [Member]
Loans	57,110	55,325
Real Estate Mortgage Portfolio Segment [Member] | Home Equity Junior Lien [Member]
Loans	63,981	67,519
Consumer Portfolio Segment [Member]
Loans	38,868	35,170	$ 35,531
Pass [Member]
Loans	2,356,343	2,267,103
Pass [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans	751,628	714,025
Pass [Member] | Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Loans	195,248	191,455
Pass [Member] | Undevelopment Land Portfolio Segment [Member]
Loans	18,484	21,022
Pass [Member] | Real Estate Mortgage Portfolio Segment [Member]
Loans	1,352,236	1,305,562
Pass [Member] | Real Estate Mortgage Portfolio Segment [Member] | Commercial Investment [Member]
Loans	591,232	538,688
Pass [Member] | Real Estate Mortgage Portfolio Segment [Member] | Owner Occupied Commercial [Member]
Loans	383,455	396,997
Pass [Member] | Real Estate Mortgage Portfolio Segment [Member] | One to Four Family Residential [Member]
Loans	256,968	247,888
Pass [Member] | Real Estate Mortgage Portfolio Segment [Member] | Home Equity First Lien [Member]
Loans	57,110	55,279
Pass [Member] | Real Estate Mortgage Portfolio Segment [Member] | Home Equity Junior Lien [Member]
Loans	63,471	66,710
Pass [Member] | Consumer Portfolio Segment [Member]
Loans	38,747	35,039
Special Mention [Member]
Loans	27,155	22,226
Special Mention [Member] | Commercial and Industrial Portfolio Segment [Member]
Loans	12,032	14,266
Special Mention [Member] | Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Loans
Special Mention [Member] | Undevelopment Land Portfolio Segment [Member]
Loans
Special Mention [Member] | Real Estate Mortgage Portfolio Segment [Member]
Loans	15,006	7,960
Special Mention [Member] | Real Estate Mortgage Portfolio Segment [Member] | Commercial Investment [Member]
Loans	3,599
Special Mention [Member] | Real Estate Mortgage Portfolio Segment [Member] | Owner Occupied Commercial [Member]
Loans	8,683	7,960
Special Mention [Member] | Real Estate Mortgage Portfolio Segment [Member] | One to Four Family Residential [Member]
Loans	2,477
Special Mention [Member] | Real Estate Mortgage Portfolio Segment [Member] | Home Equity First Lien [Member]
Loans
Special Mention [Member] | Real Estate Mortgage Portfolio Segment [Member] | Home Equity Junior Lien [Member]
Loans	247
Special Mention [Member] | Consumer Portfolio Segment [Member]
Loans	117
Substandard [Member] | Performing Financial Instruments [Member]
Loans	18,690	9,339
Substandard [Member] | Nonperforming Financial Instruments [Member]
Loans	7,382	6,707
Substandard [Member] | Commercial and Industrial Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans	14,178	5,850
Substandard [Member] | Commercial and Industrial Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans	1,176	2,700
Substandard [Member] | Construction and Development Excluding Undeveloped Land Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans		355
Substandard [Member] | Construction and Development Excluding Undeveloped Land Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans	664	538
Substandard [Member] | Undevelopment Land Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans	30
Substandard [Member] | Undevelopment Land Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans	474	474
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans	4,478	3,134
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Performing Financial Instruments [Member] | Commercial Investment [Member]
Loans	19	5
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Performing Financial Instruments [Member] | Owner Occupied Commercial [Member]
Loans	3,215	2,111
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Performing Financial Instruments [Member] | One to Four Family Residential [Member]
Loans	1,014	592
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Performing Financial Instruments [Member] | Home Equity First Lien [Member]
Loans
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Performing Financial Instruments [Member] | Home Equity Junior Lien [Member]
Loans	230	426
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans	5,068	2,864
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Nonperforming Financial Instruments [Member] | Commercial Investment [Member]
Loans	52	193
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Nonperforming Financial Instruments [Member] | Owner Occupied Commercial [Member]
Loans	3,332	1,224
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Nonperforming Financial Instruments [Member] | One to Four Family Residential [Member]
Loans	1,651	1,018
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Nonperforming Financial Instruments [Member] | Home Equity First Lien [Member]
Loans		46
Substandard [Member] | Real Estate Mortgage Portfolio Segment [Member] | Nonperforming Financial Instruments [Member] | Home Equity Junior Lien [Member]
Loans	33	383
Substandard [Member] | Consumer Portfolio Segment [Member] | Performing Financial Instruments [Member]
Loans	4
Substandard [Member] | Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans		$ 131