Stockholders' Equity and Regulatory Requirements (Details)	Dec. 31, 2020
Stockholders' Equity Note [Abstract]
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	2.37%
Total Risk Based Capital Ratio	3.50%

Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets.

No definition available.

Name:	cnob_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssetsPercentage
Namespace Prefix:	cnob_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant