Note 20 - Segments - Financial Information by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Net interest income	$ 26,164	$ 24,760	$ 76,580	$ 72,179
Provision for loan losses	150	1,250	1,650	2,500	$ 3,000
Wealth management and trust services	5,025	4,800	15,272	14,219
All other non-interest income	6,078	6,558	18,303	17,999
Non-interest expense	21,317	20,518	63,811	60,251
Income before income taxes	15,800	14,350	44,694	41,646
Income tax expense	4,096	3,883	11,597	11,235
Net income	11,704	10,467	33,097	30,411
Segment assets	3,155,913	2,938,665	3,155,913	2,938,665	$ 3,039,481
Commercial Banking [Member]
Net interest income	26,089	24,690	76,350	71,985
Provision for loan losses	150	1,250	1,650	2,500
Wealth management and trust services
All other non-interest income	6,078	6,558	18,303	17,999
Non-interest expense	18,491	17,722	54,756	51,914
Income before income taxes	13,526	12,276	38,247	35,570
Income tax expense	3,284	3,142	9,295	9,064
Net income	10,242	9,134	28,952	26,506
Segment assets	3,153,886	2,936,542	3,153,886	2,936,542
Investment Management and Trust [Member]
Net interest income	75	70	230	194
Provision for loan losses
Wealth management and trust services	5,025	4,800	15,272	14,219
All other non-interest income
Non-interest expense	2,826	2,796	9,055	8,337
Income before income taxes	2,274	2,074	6,447	6,076
Income tax expense	812	741	2,302	2,171
Net income	1,462	1,333	4,145	3,905
Segment assets	$ 2,027	$ 2,123	$ 2,027	$ 2,123