Floating interest rate on subordinated debentures.

No definition available.

Name:	cnob_FloatingInterestRateOnSubordinatedDebentures
Namespace Prefix:	cnob_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage rate added to LIBOR.

+ References

No definition available.

+ Details

Name:	cnob_PercentageRateAddedToLibor
Namespace Prefix:	cnob_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Cutstom Element.

+ References

No definition available.

+ Details

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

- Definition

Value of subordinated debentures received by Trust.

+ References

No definition available.

+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of reference rate used for variable rate of debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-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=120391452&loc=d3e13212-122682

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

+ Details

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=cnob_SubordinatedDebtFromTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Data Type:	na
Balance Type:
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- Details

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Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cnob_BankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cnob_FixedToFloatingRateSubordinatedNotesMember
Namespace Prefix:
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Subordinated Debentures (Details) - USD ($) $ in Millions	1 Months Ended			3 Months Ended	12 Months Ended
Subordinated Debentures (Details) - USD ($) $ in Millions	Jun. 30, 2020	Jan. 31, 2018	Jun. 30, 2015	Mar. 31, 2021	Dec. 31, 2020
Subordinated Debt from Trust [Member]
Subordinated Debentures (Details) [Line Items]
Value of subordinated debentures received by Trust				$ 5.0
Percentage Rate Added to Libor				2.85%
Floating interest rate on subordinated debentures				3.06%
Proceeds from Issuance of Debt				$ 5.2
Debt Instrument, Maturity Date				Jan. 23, 2034
Fixed-to-floating Rate Subordinated 2020 Notes [Member]
Subordinated Debentures (Details) [Line Items]
Proceeds from Issuance of Debt	$ 75.0
Debt Instrument, Maturity Date	Sep. 15, 2025
Debt Instrument, Interest Rate, Stated Percentage	5.75%
Debt Instrument, Description of Variable Rate Basis	Three-Month Term SOFR (as defined in the Second Supplemental Indenture), plus 560.5 basis points
Fixed-to-floating Rate Subordinated 2018 Notes [Member]
Subordinated Debentures (Details) [Line Items]
Proceeds from Issuance of Debt		$ 75.0
Debt Instrument, Maturity Date		Feb. 01, 2028
Debt Instrument, Interest Rate, Stated Percentage		5.20%
Debt Instrument, Description of Variable Rate Basis		three-month LIBOR rate plus 284 basis points
Bank [Member]
Subordinated Debentures (Details) [Line Items]
Proceeds from Issuance of Debt		$ 65.0
Fixed-to-floating Rate Subordinated Notes [Member]
Subordinated Debentures (Details) [Line Items]
Proceeds from Issuance of Debt			$ 50.0
Debt Instrument, Maturity Date					Jul. 01, 2025
Debt Instrument, Description of Variable Rate Basis					three-month LIBOR rate plus 393 basis points
Debt Instrument, Basis Spread on Variable Rate					4.16%