Summary of Significant Accounting Policies - Additional Information (Detail)	Dec. 31, 2017 USD ($)
ASU 2018-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to retained earnings	$ 1,588,198

Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act of 2017.

No definition available.

Name:	cizn_TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarnings
Namespace Prefix:	cizn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration