Note 4 - Loans, Allowance for Loan Losses and Other Real Estate Owned - Loans by Delinquency and Nonaccrual Status (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current and accruing	$ 1,195,150	$ 1,193,853
Nonaccrual	4,000	4,868
Total	1,204,844	1,207,202
Financial Asset, 30 to 59 Days Past Due [Member]
Past due and accruing	4,681	5,595
Financial Asset, 60 to 89 Days Past Due [Member]
Past due and accruing	619	2,335
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due and accruing	394	551
Commercial Portfolio Segment [Member]
Current and accruing	275,577	274,045
Nonaccrual	12
Total	276,357	275,080
Commercial Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due and accruing	747	781
Commercial Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due and accruing	21	254
Commercial Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due and accruing		0
Commercial Real Estate Portfolio Segment [Member]
Current and accruing	579,041	574,853
Nonaccrual	3,872	4,225
Total	584,221	580,480
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due and accruing	1,308	617
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due and accruing		785
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due and accruing		0
Construction Portfolio Segment [Member]
Current and accruing	3,555	3,982
Nonaccrual		0
Total	3,555	3,982
Construction Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due and accruing		0
Construction Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due and accruing		0
Construction Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due and accruing		0
Residential Portfolio Segment [Member]
Current and accruing	41,798	43,372
Nonaccrual		516
Total	41,798	44,866
Residential Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due and accruing		789
Residential Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due and accruing		189
Residential Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due and accruing		0
Consumer Portfolio Segment [Member]
Current and accruing	295,179	297,601
Nonaccrual	116	127
Total	298,913	302,794
Consumer Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due and accruing	2,626	3,408
Consumer Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due and accruing	598	1,107
Consumer Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due and accruing	$ 394	$ 551