Note 16 - Segments - Financial Information by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Commercial Banking [Member]
Net interest income	$ 24,690	$ 22,034	$ 71,985	$ 65,350
Provision for loan losses	1,250		2,500
Wealth management and trust services
All other non-interest income	6,558	5,612	17,999	16,301
Non-interest expense	17,722	15,785	51,914	46,991
Income before income taxes	12,276	11,861	35,570	34,660
Income tax expense	3,142	3,720	9,064	10,749
Net income	9,134	8,141	26,506	23,911
Investment Management and Trust [Member]
Net interest income	70	47	194	146
Provision for loan losses
Wealth management and trust services	4,800	4,373	14,219	13,576
All other non-interest income
Non-interest expense	2,796	2,645	8,337	8,085
Income before income taxes	2,074	1,775	6,076	5,637
Income tax expense	741	632	2,171	2,007
Net income	1,333	1,143	3,905	3,630
Net interest income	24,760	22,081	72,179	65,496
Provision for loan losses	1,250		2,500		$ 750
Wealth management and trust services	4,800	4,373	14,219	13,576
All other non-interest income	6,558	5,612	17,999	16,301
Non-interest expense	20,518	18,430	60,251	55,076
Income before income taxes	14,350	13,636	41,646	40,297
Income tax expense	3,883	4,352	11,235	12,756
Net income	$ 10,467	$ 9,284	$ 30,411	$ 27,541