Financing receivables maturity period.

No definition available.

Name:	cldb_FinancingReceivablesMaturityPeriod
Namespace Prefix:	cldb_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum period after which loans to be considered non performing.

+ References

No definition available.

+ Details

Name:	cldb_MinimumPeriodAfterWhichLoansToBeConsideredNonPerforming
Namespace Prefix:	cldb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Reduction of specific reserves due to favorable settlement.

+ References

No definition available.

+ Details

Name:	cldb_ReductionOfSpecificReservesDueToFavorableSettlement
Namespace Prefix:	cldb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953682-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing receivables that are current.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953401-111524

+ Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans and Allowance for Loan Losses (Details Textual)	3 Months Ended		6 Months Ended		12 Months Ended
Loans and Allowance for Loan Losses (Details Textual)	Jun. 30, 2016 USD ($) Loan	Jun. 30, 2015 Loan	Jun. 30, 2016 USD ($) Loan	Jun. 30, 2015 Loan	Jun. 30, 2016 USD ($) Loan	Jun. 30, 2015 Loan	Dec. 31, 2015 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Current Loans	$ 379,763,000		$ 379,763,000		$ 379,763,000		$ 387,145,000
Period after which loans considered nonperforming			90 days
Number of loans modified as TDRs \| Loan	0	0	0	0
Number of loans approved as TDRs, subsequently defaulted \| Loan					0	0
90-day or less term commercial loans
Accounts Notes And Loans Receivable [Line Items]
Current Loans							$ 24,200,000
Financing receivables, maturity			First quarter of 2016
Reduction of specific reserves due to favorable settlement			$ 834,000