Name:	cbkm_BusinessCombinationAcquisitionRelatedCostsNetOfTax
Namespace Prefix:	cbkm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the percentage of deposit premium required in consideration for the business combination.

No definition available.

Name:	cbkm_BusinessCombinationConsiderationTransferredDepositPremiumPercent
Namespace Prefix:	cbkm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

This element represents the amount of any measurement period credit related adjustment (as defined) realized during the reporting period to loans acquired in connection with a business combination for which the initial accounting was incomplete.

No definition available.

Name:	cbkm_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCreditRelatedAdjustment
Namespace Prefix:	cbkm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

This element represents the amount of any measurement period other loan adjustment (as defined) realized during the reporting period to loans acquired in connection with a business combination for which the initial accounting was incomplete.

No definition available.

Name:	cbkm_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLoanFactors
Namespace Prefix:	cbkm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of deposits acquired at the acquisition date.

No definition available.

Name:	cbkm_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeposits
Namespace Prefix:	cbkm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of book value of loans recognized as of the acquisition date.

No definition available.

Name:	cbkm_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansBookValue
Namespace Prefix:	cbkm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of loans receivable, after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, recognized as of the acquisition date.

No definition available.

Name:	cbkm_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansReceivableNet
Namespace Prefix:	cbkm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI https://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

Name:	us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI https://asc.fasb.org/extlink&oid=123586518&loc=d3e1043-128460

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

Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=128092470&loc=d3e4845-128472