Note 25 - Segments - Financial Information by Business Segment (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	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, 2019	Dec. 31, 2018	Dec. 31, 2017
Net interest income	$ 32,720	$ 32,070	$ 30,774	$ 29,657	$ 29,912	$ 28,521	$ 28,674	$ 27,309	$ 27,029	$ 26,173	$ 25,245	$ 25,206	$ 125,221	$ 114,416	$ 103,653
Provision for loan and leases	0	400	0	600	0	735	1,235	735	900	150	600	900	1,000	2,705	2,550
Non-interest income													22,643	21,536	20,505
All other non-interest income													27,147	23,810	23,994
Non-interest expenses	26,291	23,957	25,464	22,639	24,565	21,781	22,136	21,027	27,048	21,168	21,209	20,995	98,351	89,509	90,420
Income before income tax expense	19,590	21,017	17,573	17,480	16,923	17,431	16,738	16,456	10,488	15,800	14,961	13,933	75,660	67,548	55,182
Income tax expense	2,941	3,783	1,030	1,839	2,265	3,555	3,159	3,052	5,542	4,096	4,359	3,142	9,593	12,031	17,139
Net income	16,649	$ 17,234	$ 16,543	$ 15,641	14,658	$ 13,876	$ 13,579	$ 13,404	4,946	$ 11,704	$ 10,602	$ 10,791	66,067	55,517	38,043
Total assets	3,724,197				3,302,924				3,239,646				3,724,197	3,302,924	3,239,646
Commercial Banking [Member]
Net interest income													124,902	114,161	103,352
Provision for loan and leases													1,000	2,705	2,550
Non-interest income													0	0	0
All other non-interest income													27,147	23,810	23,994
Non-interest expenses													85,642	76,963	78,181
Income before income tax expense													65,407	58,303	46,615
Income tax expense													7,368	10,025	14,080
Net income													58,039	48,278	32,535
Total assets	3,720,502				3,299,169				3,237,656				3,720,502	3,299,169	3,237,656
Investment Management and Trust [Member]
Net interest income													319	255	301
Provision for loan and leases													0	0	0
Non-interest income													22,643	21,536	20,505
All other non-interest income													0	0	0
Non-interest expenses													12,709	12,546	12,239
Income before income tax expense													10,253	9,245	8,567
Income tax expense													2,225	2,006	3,059
Net income													8,028	7,239	5,508
Total assets	$ 3,695				$ 3,755				$ 1,990				$ 3,695	$ 3,755	$ 1,990