Note 19 - Quarterly Financial Information (Unaudited) - Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest and loan fee income	$ 71,052	$ 72,848	$ 70,489	$ 69,624	$ 69,198	$ 60,802	$ 47,997	$ 43,759	$ 43,041	$ 43,810	$ 44,276	$ 42,316	$ 284,013	$ 221,756	$ 173,443
Net interest income	69,373	71,715	69,882	69,153	68,723	60,315	47,514	43,279	42,537	43,318	43,792	41,841	280,123	219,831	171,488
Reversal of Provision for Credit Losses	0	400	0	(1,550)	0	0	0	0	0	0	0	0	(1,150)	0	0
Noninterest income	10,992	11,281	10,700	10,549	10,463	11,818	11,264	11,576	10,842	11,282	11,032	10,189	43,522	45,121	43,345
Noninterest expense	25,517	25,650	25,839	26,210	25,090	24,767	24,629	24,875	23,912	24,697	24,291	24,906	103,216	99,361	97,806
Income before taxes and equity in undistributed income of subsidiaries	54,848	56,946	54,743	55,042	54,096	47,366	34,149	29,980	29,467	29,903	30,533	27,124	221,579	165,591	117,027
Net Income	$ 39,468	$ 41,601	$ 40,248	$ 40,451	$ 39,344	$ 34,760	$ 25,314	$ 22,616	$ 21,720	$ 22,063	$ 22,579	$ 20,147	$ 161,768	$ 122,034	$ 86,509
Basic earnings per common share (in dollars per share)	$ 1.48	$ 1.56	$ 1.51	$ 1.51	$ 1.46	$ 1.29	$ 0.94	$ 0.84	$ 0.81	$ 0.82	$ 0.84	$ 0.75	$ 6.06	$ 4.54	$ 3.22
Diluted earnings per common share (in dollars per share)	1.48	1.56	1.51	1.51	1.46	1.29	0.94	0.84	0.81	0.82	0.84	0.75	6.06	4.54	3.22
Dividends paid (in dollars per share)	0.44	0.44	0.42	0.42	0.42	0.42	0.42	0.42	0.42	0.41	0.41	0.41	1.72	1.68	1.65
Share price, common stock (in dollars per share)	56.41												56.41
Minimum [Member]
Share price, common stock (in dollars per share)	42.59	38.87	36.85	44.04	52.22	52.29	55.66	57.54	53.78	54.03	57.67	55.82	42.59	52.22	53.78
Maximum [Member]
Share price, common stock (in dollars per share)	$ 57.21	$ 49.87	$ 43.5	$ 58.34	$ 63.39	$ 61.52	$ 61.3	$ 62.76	$ 58	$ 58.55	$ 64.8	$ 66.43	$ 57.21	$ 63.39	$ 58