Quarterly Financial Information of ConnectOne Bancorp, Inc. (Unaudited) (Details) - Schedule of Quarterly Financial Information - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Quarterly Financial Information [Abstract]
Total interest income	$ 41,499	$ 41,178	$ 40,038	$ 38,526	$ 37,230	$ 36,186	$ 34,181	$ 33,370	$ 161,241	$ 140,967	$ 94,207
Total interest expense	8,092	8,154	7,644	7,206	6,774	6,459	5,503	5,078	31,096	23,814	14,808
Net interest income	33,407	33,024	32,394	31,320	30,456	29,727	28,678	28,292	130,145	117,153	79,399
Provision for loan and lease losses	25,200	6,750	3,750	3,000	5,055	4,175	1,550	1,825	38,700	12,605	4,683
Total other income, net of securities gains	1,573	1,445	1,467	1,202	1,225	1,752	3,215	1,049
Net securities (losses) gains		4,131	103		1,138	2,067	221	506
Other expense	15,252	14,551	14,352	14,353	13,579	13,301	14,974	12,631
Income before income taxes	(5,472)	17,299	15,862	15,169	14,185	16,070	15,590	15,391	42,858	61,237	27,410
Income tax expense	(3,448)	5,443	5,003	4,778	4,617	5,228	5,069	5,012	11,776	19,926	8,845
Net income	(2,024)	11,856	10,859	10,391	9,568	10,842	10,521	10,379	31,082	41,311	18,565
Preferred dividends				22	28	28	28	28		112	112
Net income available to common stockholders	$ (2,024)	$ 11,856	$ 10,859	$ 10,369	$ 9,540	$ 10,814	$ 10,493	$ 10,351	$ 31,060	$ 41,199	$ 18,453
Earnings per share:
Basic (in Dollars per share)	$ (0.07)	$ 0.39	$ 0.36	$ 0.35	$ 0.32	$ 0.36	$ 0.35	$ 0.35	$ 1.02	$ 1.37	$ 0.80
Diluted (in Dollars per share)	$ (0.07)	$ 0.39	$ 0.36	$ 0.34	$ 0.31	$ 0.36	$ 0.35	$ 0.34	$ 1.01	$ 1.36	$ 0.79