Fair Value Measurements and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Impaired Financing Receivable, Related Allowance	$ 110	$ 145
Loans held-for-sale requiring valuation allowance, gross carrying amount	62,700	65,600
Loans held-for-sale requiring valuation allowance, amount of allowance	15,300
Impaired Loans [Member]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,300	1,200
Impaired Financing Receivable, Related Allowance	$ 100	$ 100

Loans held-for-sale requiring valuation allowance, gross carrying amount.

No definition available.

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Period Type:	instant

- Definition

Loans held-for-sale requiring valuation allowance, amount of allowance.

+ References

No definition available.

+ Details

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Namespace Prefix:	cnob_
Data Type:	xbrli:monetaryItemType
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- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

+ Details

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Period Type:	instant

- Details

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