Loans - Changes in Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2015 USD ($) Loan	Dec. 31, 2014 USD ($) Loan
Receivables [Abstract]
Number of Loans, Charge-off \| Loan	1
Number of Loans \| Loan	3	4
Additional loans with concessions, Recorded Investment	$ 0
Charge-off, Recorded Investment	(349)
Principal paydowns, Recorded Investment	(534)
Post-Modification Outstanding Recorded Investment	$ 3,858	$ 4,741

Financing Receivable, Modifications, Collections During Period

No definition available.

Name:	cizn_FinancingReceivableModificationsCollectionsDuringPeriod
Namespace Prefix:	cizn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Financing Receivable, Modifications, Recorded Investment During Period

+ References

No definition available.

+ Details

Name:	cizn_FinancingReceivableModificationsRecordedInvestmentDuringPeriod
Namespace Prefix:	cizn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of loans charged off

+ References

No definition available.

+ Details

Name:	cizn_NumberOfLoansChargedOff
Namespace Prefix:	cizn_
Data Type:	xbrli:integerItemType
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=49124121&loc=SL6953676-111524

+ Details

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

- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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=25495931&loc=d3e18845-111554

+ Details

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

- References

No definition available.

+ Details

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