Note 15 - Segments - Financial Information by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Commercial Banking [Member]
Net interest income	$ 23,888	$ 21,756	$ 47,295	$ 43,316
Provision for loan losses	750		1,250
Investment management and trust services
All other non-interest income	5,971	5,568	11,441	10,689
Non-interest expense	17,297	16,015	34,192	31,206
Income before income taxes	11,812	11,309	23,294	22,799
Tax expense	2,971	3,495	5,922	7,029
Net income	8,841	7,814	17,372	15,770
Investment Management and Trust [Member]
Net interest income	62	45	124	99
Provision for loan losses
Investment management and trust services	4,807	4,651	9,419	9,203
All other non-interest income
Non-interest expense	2,896	2,852	5,541	5,440
Income before income taxes	1,973	1,844	4,002	3,862
Tax expense	705	656	1,430	1,375
Net income	1,268	1,188	2,572	2,487
Net interest income	23,950	21,801	47,419	43,415
Provision for loan losses	750		1,250		$ 750
Investment management and trust services	4,807	4,651	9,419	9,203
All other non-interest income	5,971	5,568	11,441	10,689
Non-interest expense	20,193	18,867	39,733	36,646
Income before income taxes	13,785	13,153	27,296	26,661
Tax expense	3,676	4,151	7,352	8,404
Net income	$ 10,109	$ 9,002	$ 19,944	$ 18,257