Note 25 - Segments - Financial Information by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net interest income	$ 29,912	$ 28,521	$ 28,674	$ 27,309	$ 27,029	$ 26,173	$ 25,245	$ 25,206	$ 25,079	$ 24,762	$ 23,957	$ 23,491	$ 114,416	$ 103,653	$ 97,289
Provision		735	1,235	735	900	150	600	900	500	1,250	750	500	2,705	2,550	3,000
Non-interest income													23,810	23,994	23,765
All other non-interest income													23,810	23,994	23,765
Non-interest expense	24,565	21,781	22,136	21,027	27,048	21,168	21,209	20,995	21,119	20,364	20,051	19,404	89,509	90,420	80,938
Income before income taxes	16,923	17,431	16,738	16,456	10,488	15,800	14,961	13,933	14,625	14,350	13,785	13,511	67,548	55,182	56,271
Income tax expense	2,265	3,555	3,159	3,052	5,542	4,096	4,359	3,142	4,009	3,883	3,676	3,676	12,031	17,139	15,244
Net income	14,658	$ 13,876	$ 13,579	$ 13,404	4,946	$ 11,704	$ 10,602	$ 10,791	10,616	$ 10,467	$ 10,109	$ 9,835	55,517	38,043	41,027
Segment assets	3,302,924				3,239,646				3,039,481				3,302,924	3,239,646	3,039,481
Fiduciary and Trust [Member]
Non-interest income													21,536	20,505	19,155
Commercial Banking [Member]
Net interest income													114,161	103,352	97,021
Provision													2,705	2,550	3,000
All other non-interest income													23,810	23,994	23,765
Non-interest expense													76,963	78,181	69,648
Income before income taxes													58,303	46,615	48,138
Income tax expense													10,025	14,080	12,340
Net income													48,278	32,535	35,798
Segment assets	3,301,108				3,237,656				3,037,394				3,301,108	3,237,656	3,037,394
Commercial Banking [Member] | Fiduciary and Trust [Member]
Non-interest income
Investment Management and Trust [Member]
Net interest income													255	301	268
Provision
All other non-interest income
Non-interest expense													12,546	12,239	11,290
Income before income taxes													9,245	8,567	8,133
Income tax expense													2,006	3,059	2,904
Net income													7,239	5,508	5,229
Segment assets	$ 1,816				$ 1,990				$ 2,087				1,816	1,990	2,087
Investment Management and Trust [Member] | Fiduciary and Trust [Member]
Non-interest income													$ 21,536	$ 20,505	$ 19,155