Interest Income Forgone on Loans

No definition available.

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

- Definition

Loan To Value Ratio

+ References

No definition available.

+ Details

Name:	cizn_LoanToValueRatio
Namespace Prefix:	cizn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Minimum default loan limit to be considered for individually evaluation of impaired financing receivable.

+ References

No definition available.

+ Details

Name:	cizn_MinimumDefaultLoanLimitToBeConsideredForIndividuallyEvaluationOfImpairedFinancingReceivable
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

+ Details

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

- Definition

Amount of loan with variable or adjustable rate of interest.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

+ Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cizn_RestructuredLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Loans - Additional Information (Detail) - USD ($)	12 Months Ended
Loans - Additional Information (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Variable rate outstanding loans	$ 67,500,000	$ 48,700,000
Interest income forgone on loans classified as non-accrual	428,644	412,915	$ 651,560
Minimum loan limit considered for impairment evaluation by management	100,000
Restructured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 174,274	$ 174,274
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan-to-value ratios	80.00%
Commercial Real Estate [Member] \| Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan-to-value ratios	80.00%
Commercial Real Estate [Member] \| Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan-to-value ratios	50.00%
Consumer Loans [Member] \| Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan-to-value ratios	80.00%