Note 3 - Loans - Aging of the Recorded Investment in Loans (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Current	$ 2,258,481,000	$ 2,295,871,000
Past due	14,297,000	9,504,000
Loans	2,272,778,000	2,305,375,000
Recorded investment greater than 90 days and accruing	0	438,000	$ 0
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	8,068,000	2,589,000
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	1,130,000	1,182,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	5,099,000	5,733,000
Commercial and Industrial Portfolio Segment [Member]
Current	730,458,000	734,682,000
Past due	6,175,000	2,159,000
Loans	736,633,000	736,841,000
Recorded investment greater than 90 days and accruing		18,000
Commercial and Industrial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	4,262,000	84,000
Commercial and Industrial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		290,000
Commercial and Industrial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	1,913,000	1,785,000
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Current	165,363,000	191,810,000
Past due	469,000	538,000
Loans	165,832,000	192,348,000
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	25,000
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	444,000	538,000
Undevelopment Land Portfolio Segment [Member]
Current	20,733,000	21,022,000
Past due	474,000	474,000
Loans	21,207,000	21,496,000
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	474,000	474,000
Real Estate Mortgage Portfolio Segment [Member]
Current	1,307,220,000	1,313,392,000
Past due	7,177,000	6,128,000
Loans	1,314,397,000	1,319,520,000
Recorded investment greater than 90 days and accruing		420,000
Real Estate Mortgage Portfolio Segment [Member] | Commercial Investment [Member]
Current	545,153,000	537,998,000
Past due	1,804,000	888,000
Loans	546,957,000	538,886,000
Recorded investment greater than 90 days and accruing		86,000
Real Estate Mortgage Portfolio Segment [Member] | Owner Occupied Commercial [Member]
Current	404,628,000	406,726,000
Past due	1,581,000	1,566,000
Loans	406,209,000	408,292,000
Recorded investment greater than 90 days and accruing		182,000
Real Estate Mortgage Portfolio Segment [Member] | One to Four Family Residential [Member]
Current	240,903,000	246,730,000
Past due	3,446,000	2,768,000
Loans	244,349,000	249,498,000
Recorded investment greater than 90 days and accruing		34,000
Real Estate Mortgage Portfolio Segment [Member] | Home Equity First Lien [Member]
Current	51,073,000	55,027,000
Past due	3,000	298,000
Loans	51,076,000	55,325,000
Recorded investment greater than 90 days and accruing		46,000
Real Estate Mortgage Portfolio Segment [Member] | Home Equity Junior Lien [Member]
Current	65,463,000	66,911,000
Past due	343,000	608,000
Loans	65,806,000	67,519,000
Recorded investment greater than 90 days and accruing		72,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	3,781,000	2,477,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Investment [Member]
Past due	903,000	631,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Owner Occupied Commercial [Member]
Past due	345,000	342,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | One to Four Family Residential [Member]
Past due	2,362,000	1,174,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity First Lien [Member]
Past due	3,000	231,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity Junior Lien [Member]
Past due	168,000	99,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	1,128,000	787,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Investment [Member]
Past due	732,000	64,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Owner Occupied Commercial [Member]
Past due
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | One to Four Family Residential [Member]
Past due	396,000	576,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity First Lien [Member]
Past due		21,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity Junior Lien [Member]
Past due		126,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	2,268,000	2,864,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Investment [Member]
Past due	169,000	193,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Owner Occupied Commercial [Member]
Past due	1,236,000	1,224,000
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	688,000	1,018,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity First Lien [Member]
Past due		46,000
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity Junior Lien [Member]
Past due	175,000	383,000
Consumer Portfolio Segment [Member]
Current	34,707,000	34,965,000
Past due	2,000	205,000
Loans	34,709,000	35,170,000
Recorded investment greater than 90 days and accruing
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due		28,000
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	2,000	105,000
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due		$ 72,000