Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Disclosure Text Block [Abstract]
Time Deposits Maturities, after Next Twelve Months	$ 1,400,000	$ 1,200,000
Brokered Time Deposits	405,600	358,700
Time Deposits 250000 or More	272,200	198,300
Brokered Time Deposits with Balances	$ 8,800	$ 0

The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of brokered time deposits.

No definition available.

+ Details

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Namespace Prefix:	cnob_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $250,000 or more.

+ References

No definition available.

+ Details

Name:	cnob_TimeDeposits250000OrMore
Namespace Prefix:	cnob_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of cash received as security in return for loaning securities to another party.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04(11))
-URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Amount of time deposits maturing after the next fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=50488274&loc=d3e64164-112818

+ Details

Name:	us-gaap_TimeDepositsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant