Loans and the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
LOANS AND THE ALLOWANCE FOR LOAN LOSSES (Details) [Line Items]
Non Accrual Contractual Due	90 days
Loans held-for-sale, Carrying Amount	$ 62,255		$ 78,005
Loans Pledged as Collateral	1,800,000		1,800,000
Loans performing under the restructured terms	10,000		13,300
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	4,900		500
Troubled debt restructurings	14,900		13,800
Allowance for Loan and Lease Losses Period Increase Decrease Due to Trouble Debt Restructuring	$ 8,000
Debt Instrument, Interest Rate, Stated Percentage Rate Range	3.00%
Increase in allowance for loan and lease losses		$ 45
Number of loans	Six loans were accruing prior to modification, while five remained in accrual status post-modification.
Minimum [Member]
LOANS AND THE ALLOWANCE FOR LOAN LOSSES (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range	1.30%
Maximum [Member]
LOANS AND THE ALLOWANCE FOR LOAN LOSSES (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range	1.60%
Commercial loans held-for-sale segment [Member]
LOANS AND THE ALLOWANCE FOR LOAN LOSSES (Details) [Line Items]
Loans held-for-sale, Carrying Amount	$ 61,300		65,600
Loans held-for-sale net of valuation allowance	$ 2,600		$ 0

Allowance for loan and lease losses period increase decrease due to trouble debt restructuring.

No definition available.

Name:	cnob_AllowanceForLoanAndLeaseLossesPeriodIncreaseDecreaseDueToTroubleDebtRestructuring
Namespace Prefix:	cnob_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Loans and the allowance for loan losses details line items.

+ References

No definition available.

+ Details

Name:	cnob_LOANSANDTHEALLOWANCEFORLOANLOSSESDetailsLineItems
Namespace Prefix:	cnob_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans performing under the restructured terms

+ References

No definition available.

+ Details

Name:	cnob_LoansPerformingUnderRestructuredTerms
Namespace Prefix:	cnob_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Loans held-for-sale net of valuation allowance.

+ References

No definition available.

+ Details

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

- Definition

Non accrual contractual due.

+ References

No definition available.

+ Details

Name:	cnob_NonAccrualContractualDue
Namespace Prefix:	cnob_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of loans.

+ References

No definition available.

+ Details

Name:	cnob_NumberOfLoans
Namespace Prefix:	cnob_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Reflects the amount of the write-down related to a troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

+ Details

Name:	us-gaap_FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18794-111554

+ Details

Name:	us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5086-111524

+ Details

Name:	us-gaap_LoansPledgedAsCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The face amount of loans that will be sold to other entities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

+ Details

Name:	us-gaap_LoansReceivableHeldForSaleAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

For a debtor, the gain (loss) recognized on the transfer of assets, after the impact of income tax expense or benefit, arising from the difference between the book value of the assets transferred before the restructuring and the fair value of the assets transferred.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 60
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6402221&loc=d3e15743-112638

+ Details

Name:	us-gaap_TroubledDebtRestructuringDebtorCurrentPeriodGainLossOnTransferOfAssetsNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cnob_CommercialLoansHeldForSaleSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: