Note 23 - Quarterly Financial Information of ConnectOne Bancorp, Inc. (Unaudited) - Schedule of Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Total interest income	$ 128,033	$ 130,242	$ 130,007	$ 129,607	$ 128,957	$ 123,686	$ 121,325	$ 116,097	$ 517,889	$ 490,065	$ 373,746
Total interest expense	63,322	69,355	68,568	69,307	67,135	61,329	57,482	49,013
Net interest income	64,711	60,887	61,439	60,300	61,822	62,357	63,843	67,084	247,337	255,106	302,119
Provision for credit losses	3,500	3,800	2,500	4,000	2,700	1,500	3,000	1,000	13,984	8,424	17,066
Total other income	3,744	4,737	4,399	3,848	4,209	3,562	3,438	2,792
Other expenses	38,498	38,641	37,594	37,065	37,845	35,784	35,450	34,870
Income before income tax expense	26,457	23,183	25,744	23,083	25,486	28,635	28,831	34,006	98,467	116,958	171,224
Income tax expense	6,086	6,022	6,688	5,878	6,213	7,228	7,437	9,077	24,674	29,955	46,013
Net income	20,371	17,161	19,056	17,205	19,273	21,407	21,394	24,929	73,793	87,003	125,211
Preferred dividends	1,509	1,509	1,509	1,509	1,509	1,509	1,509	1,509	6,036	6,036	6,037
Net income available to common stockholders	$ 18,862	$ 15,652	$ 17,547	$ 15,696	$ 17,764	$ 19,898	$ 19,885	$ 23,420	$ 67,757	$ 80,967	$ 119,174
Basic (in dollars per share)	$ 0.49	$ 0.41	$ 0.46	$ 0.41	$ 0.46	$ 0.51	$ 0.51	$ 0.6	$ 1.77	$ 2.08	$ 3.03
Diluted (in dollars per share)	$ 0.49	$ 0.41	$ 0.46	$ 0.41	$ 0.46	$ 0.51	$ 0.51	$ 0.59	$ 1.76	$ 2.07	$ 3.01