Note 6 - Fair Value Measurements and Fair Value of Financial Instruments (Details Textual) - Collateral Pledged [Member] - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Impaired Financing Receivable, with Related Allowance, Recorded Investment 1	$ 1.0	$ 7.7
Impaired Financing Receivable, Related Allowance 1	$ 0.3	$ 1.4

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

No definition available.

Name:	cnob_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment1
Namespace Prefix:	cnob_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant