Loans (Details 4) - USD ($) $ in Thousands	Dec. 31, 2015	Jun. 30, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment, Loans non-accrual	$ 3,498	$ 2,269
Recorded investment, Loans Past Due Over 90 Days Still Accruing	0	0
Construction Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment, Loans non-accrual	22	0
Recorded investment, Loans Past Due Over 90 Days Still Accruing	0	0
Other Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment, Loans non-accrual	2,571	2,079
Recorded investment, Loans Past Due Over 90 Days Still Accruing	0	0
Residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment, Loans non-accrual	343	190
Recorded investment, Loans Past Due Over 90 Days Still Accruing	0	0
Residential Real Estate Non Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment, Loans non-accrual	562	0
Recorded investment, Loans Past Due Over 90 Days Still Accruing	$ 0	$ 0

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.

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5111-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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