Note 5 - Loans - Aging of the Recorded Investment in Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current	$ 2,537,627	$ 2,397,731
Past due	10,544	11,839
Loans	2,548,171	2,409,570	$ 2,305,375
Recorded investment greater than 90 days and accruing	745	2
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	5,112	4,151
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	2,076	1,175
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	3,356	6,513
Commercial and Industrial Portfolio Segment [Member]
Current	832,923	776,118
Past due	601	2,896
Loans	833,524	779,014	736,841
Recorded investment greater than 90 days and accruing	12
Commercial and Industrial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	197	2,571
Commercial and Industrial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	200	4
Commercial and Industrial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	204	321
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member]
Current	224,732	194,936
Past due	318	976
Loans	225,050	195,912	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		312
Construction and Development Excluding Undeveloped Land Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	318	664
Undevelopment Land Portfolio Segment [Member]
Current	29,552	18,514
Past due	540	474
Loans	30,092	18,988	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	66
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	1,402,362	1,369,464
Past due	9,085	7,324
Loans	1,411,447	1,376,788	1,319,520
Recorded investment greater than 90 days and accruing	733	2
Real Estate Mortgage Portfolio Segment [Member] | Commercial Investment [Member]
Current	586,884	594,242
Past due	1,726	660
Loans	588,610	594,902
Recorded investment greater than 90 days and accruing	99
Real Estate Mortgage Portfolio Segment [Member] | Owner Occupied Commercial [Member]
Current	421,143	394,623
Past due	5,230	4,062
Loans	426,373	398,685
Recorded investment greater than 90 days and accruing	535
Real Estate Mortgage Portfolio Segment [Member] | One to Four Family Residential [Member]
Current	274,547	259,994
Past due	1,470	2,116
Loans	276,017	262,110
Recorded investment greater than 90 days and accruing
Real Estate Mortgage Portfolio Segment [Member] | Home Equity First Lien [Member]
Current	49,321	56,938
Past due	179	172
Loans	49,500	57,110
Recorded investment greater than 90 days and accruing
Real Estate Mortgage Portfolio Segment [Member] | Home Equity Junior Lien [Member]
Current	70,467	63,667
Past due	480	314
Loans	70,947	63,981
Recorded investment greater than 90 days and accruing	99	2
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	4,849	1,494
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Investment [Member]
Past due	1,382	608
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Owner Occupied Commercial [Member]
Past due	2,732	455
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | One to Four Family Residential [Member]
Past due	374	172
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity First Lien [Member]
Past due	179	172
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member] | Home Equity Junior Lien [Member]
Past due	182	87
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	1,876	776
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Investment [Member]
Past due	107
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Owner Occupied Commercial [Member]
Past due	1,377	275
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | One to Four Family Residential [Member]
Past due	336	307
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity First Lien [Member]
Past due
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member] | Home Equity Junior Lien [Member]
Past due	56	194
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	2,360	5,054
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Investment [Member]
Past due	237	52
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Owner Occupied Commercial [Member]
Past due	1,121	3,332
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	760	1,637
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity First Lien [Member]
Past due
Real Estate Mortgage Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home Equity Junior Lien [Member]
Past due	242	33
Consumer Portfolio Segment [Member]
Current	48,058	38,699
Past due		169
Loans	48,058	38,868	$ 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		86
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		83
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due