Note 26 - Quarterly Operating Results (Unaudited) - Quarterly Operating Results (Details) - USD ($) $ / shares in Units, $ 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
Interest income	$ 35,004	$ 33,021	$ 32,004	$ 29,744	$ 29,098	$ 28,120	$ 27,026	$ 26,655	$ 26,372	$ 25,944	$ 25,169	$ 24,722	$ 129,773	$ 110,899	$ 102,207
Interest expense	5,092	4,500	3,330	2,435	2,069	1,947	1,781	1,449	1,293	1,182	1,212	1,231	15,357	7,246	4,918
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
Net interest income after provision	29,912	27,786	27,439	26,574	26,129	26,023	24,645	24,306	24,579	23,512	23,207	22,991	111,711	101,103	94,289
Non-interest income	11,576	11,426	11,435	10,909	11,407	10,945	11,525	10,622	11,165	11,202	10,629	9,924	45,346	44,499	42,920
Non-interest expenses	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
Basic earnings per share (in dollars per share)	$ 0.65	$ 0.61	$ 0.60	$ 0.59	$ 0.22	$ 0.52	$ 0.47	$ 0.48	$ 0.47	$ 0.47	$ 0.45	$ 0.44	$ 2.45	$ 1.69	$ 1.84
Diluted earnings per share (in dollars per share)	$ 0.64	$ 0.60	$ 0.59	$ 0.58	$ 0.22	$ 0.51	$ 0.46	$ 0.47	$ 0.46	$ 0.46	$ 0.45	$ 0.44	$ 2.42	$ 1.66	$ 1.80