Note 16 - Segments - Financial Information by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Net interest income	$ 25,184	$ 23,469
Provision for loan losses	900	500	$ 3,000
Wealth management and trust services	5,094	4,612
All other non-interest income	5,703	5,470
Non-interest expense	21,148	19,540
Income before income taxes	13,933	13,511
Income tax expense	3,142	3,676
Net income	10,791	9,835
Segment assets	3,033,343	2,824,107	$ 3,039,481
Commercial Banking [Member]
Net interest income	25,107	23,407
Provision for loan losses	900	500
Wealth management and trust services
All other non-interest income	5,703	5,470
Non-interest expense	18,101	16,896
Income before income taxes	11,809	11,481
Income tax expense	2,384	2,951
Net income	9,425	8,530
Segment assets	3,031,318	2,823,861
Investment Management and Trust [Member]
Net interest income	77	62
Provision for loan losses
Wealth management and trust services	5,094	4,612
All other non-interest income
Non-interest expense	3,047	2,644
Income before income taxes	2,124	2,030
Income tax expense	758	725
Net income	1,366	1,305
Segment assets	$ 2,025	$ 246