v3.22.2

Loans and Allowance for Loan Losses - Additional Information (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2022 USD ($) item customer	Dec. 31, 2021 USD ($) item
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDR modified that subsequently defaulted \| item	0	0
Non-accrual loans excluding TDRs	$ 761,420	$ 990,000
Minimum consecutive period of payment performance	6 months
Number of foreclosed real estate properties \| item	0
Mortgage loans in process of foreclosure	$ 54,408
Number of consumer for mortgage loan in process of foreclosure \| customer	1
Residential Portfolio Segment [Member] \| 59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of TDRs \| item	0
Entity Loan Modification Program [Member] \| Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans on accrual status	$ 637,820
Entity Loan Modification Program [Member] \| Multi Family And Nonresidential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans on accrual status	$ 123,600

Amount of accrued troubled debt restructuring.

+ References

No definition available.

+ Details

Name:	cnnb_FinancingReceivableAccruedTroubledDebtRestructuring
Namespace Prefix:	cnnb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Minimum consecutive period of payment performance under existing or modified terms for borrowers with loans designated as TDRs to be placed back on accrual status.

+ References

No definition available.

+ Details

Name:	cnnb_MinimumConsecutivePeriodOfPaymentPerformance
Namespace Prefix:	cnnb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of consumer for mortgage loan in process of foreclosure.

+ References

No definition available.

+ Details

Name:	cnnb_NumberOfConsumerForMortgageLoanInProcessOfForeclosure
Namespace Prefix:	cnnb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of foreclosed real estate properties at end of period.

+ References

No definition available.

+ Details

Name:	cnnb_NumberOfForeclosedRealEstateProperties
Namespace Prefix:	cnnb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Accrual status of troubled debt restructuring on financing receivable.

+ References

No definition available.

+ Details

Name:	cnnb_TroubledDebtRestructuringOnFinancingReceivableAccrualStatus
Namespace Prefix:	cnnb_
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

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI https://asc.fasb.org/extlink&oid=123577603&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 receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953682-111524

+ Details

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

- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 35
-URI https://asc.fasb.org/extlink&oid=123577603&loc=SL49126937-111524

+ Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=cnnb_FinancialAsset59DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationNameAxis=us-gaap_EntityLoanModificationProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Cincinnati Bancorp, Inc. 10-Q