Note 11 - Commitments with Off-balance Sheet Risk (Details Textual) - USD ($) $ in Thousands	12 Months Ended
Jun. 30, 2016	Jun. 30, 2015
Minimum [Member]
Loans and Leases Receivable Commitments Variable Rates Percentage	2.00%	2.00%
Loans and Leases Receivable Commitments Fixed Rates Percentage	3.10%	2.25%
Maximum [Member]
Loans and Leases Receivable Commitments Variable Rates Percentage	7.50%	7.25%
Loans and Leases Receivable Commitments Fixed Rates Percentage	5.99%	6.00%
Financial Standby Letter of Credit [Member]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 1,032	$ 890
Commitments to Extend Credit [Member]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	7,829	7,676
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	46,696	43,135
Loans and Leases Receivable, Commitments, Variable Rates	44,228	36,502
Loans and Leases Receivable, Commitments, Fixed Rates	$ 2,468	$ 6,633

The lowest stated interest rate within the commitments to fund advances to borrowers at fixed interest rates.

No definition available.

Name:	cbkm_LoansAndLeasesReceivableCommitmentsFixedRatesPercentage
Namespace Prefix:	cbkm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The lowest stated interest rate within the commitments to fund advances to borrowers at variable interest rates.

+ References

No definition available.

+ Details

Name:	cbkm_LoansAndLeasesReceivableCommitmentsVariableRatesPercentage
Namespace Prefix:	cbkm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13537-108611

+ Details

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

- Definition

The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

No definition available.

+ Details

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

- Definition

Reflects the amount of cash required to fully fund agreements to provide advances to borrowers and lessees at stated interest rates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=68064133&loc=d3e61044-112788

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=68064133&loc=d3e61082-112788

+ Details

Name:	us-gaap_LoansAndLeasesReceivableCommitmentsFixedRates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Reflects the amount of cash required to fully fund agreements to provide advances to borrowers and lessees at interest rates that increase or decrease depending on certain facts or circumstances.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=68064133&loc=d3e61082-112788

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=68064133&loc=d3e61044-112788

+ Details

Name:	us-gaap_LoansAndLeasesReceivableCommitmentsVariableRates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_FinancialStandbyLetterOfCreditMember
Namespace Prefix:
Data Type:	na
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- Details

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