Note 12 - Fair Value - Quantitative Information about Level 3 Fair Value Measurements (Details) - USD ($) $ in Thousands	12 Months Ended
Jun. 30, 2016	Jun. 30, 2015
Commercial Real Estate - Other [Member] \| Settlement Contract [Member] \| Weighted Average [Member]
Discount Rate	0.00%	91.80%
Commercial Real Estate - Other [Member] \| Settlement Contract [Member]
Fair Value	$ 459	$ 4
Valuation Technique	Settlement Contract	Settlement Contract
Unobservable Inputs	N/A	Adjustment for difference between loan balance and settlement value
Discount Rate	0.00%	(91.80%)
Commercial Real Estate - Other [Member] \| Income Approach Valuation Technique [Member] \| Weighted Average [Member]
Discount Rate		40.00%
Commercial Real Estate - Other [Member] \| Income Approach Valuation Technique [Member]
Fair Value		$ 733
Valuation Technique		Income approach
Unobservable Inputs		Liquidation adjustment for distressed sales
Discount Rate		(40.00%)
Commercial Real Estate - Other [Member] \| Bid Indications [Member] \| Weighted Average [Member]
Discount Rate	0.00%
Commercial Real Estate - Other [Member] \| Bid Indications [Member]
Fair Value	$ 127
Valuation Technique	Bid Indications
Unobservable Inputs	N/A
Discount Rate	0.00%
Commercial Real Estate - Other [Member] \| Cost Approach Valuation Technique [Member] \| Weighted Average [Member]
Discount Rate		40.00%
Commercial Real Estate - Other [Member] \| Cost Approach Valuation Technique [Member]
Fair Value		$ 125
Valuation Technique		Cost approach
Unobservable Inputs		Liquidation adjustment for distressed sales
Discount Rate		(40.00%)
Commercial Real Estate - Other [Member] \| Market Approach Valuation Technique [Member] \| Weighted Average [Member]
Discount Rate		11.70%
Commercial Real Estate - Other [Member] \| Market Approach Valuation Technique [Member] \| Minimum [Member]
Discount Rate		82.90%
Commercial Real Estate - Other [Member] \| Market Approach Valuation Technique [Member] \| Maximum [Member]
Discount Rate		(71.60%)
Commercial Real Estate - Other [Member] \| Market Approach Valuation Technique [Member]
Fair Value		$ 1,121
Valuation Technique		Sales comparison approach
Unobservable Inputs		Adjustment for differences between comparable sales
Commercial Real Estate Other 2 [Member] \| Bid Indications [Member] \| Weighted Average [Member]
Discount Rate	0.00%
Commercial Real Estate Other 2 [Member] \| Bid Indications [Member]
Fair Value	$ 620
Valuation Technique	Bid Indications
Unobservable Inputs	N/A
Discount Rate	0.00%
Residential Real Estate Non-owner Occupied Loans [Member] \| Bid Indications [Member] \| Weighted Average [Member]
Discount Rate	0.00%
Residential Real Estate Non-owner Occupied Loans [Member] \| Bid Indications [Member]
Fair Value	$ 197
Valuation Technique	Bid Indications
Unobservable Inputs	N/A
Discount Rate	0.00%

It represents the interest rate used to measure fair value.

No definition available.

Name:	cbkm_FairValueInputRate
Namespace Prefix:	cbkm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

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

- Definition

Description of significant assumptions used by management to measure fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13433-108611

+ Details

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

- Definition

Description of the inputs and valuation technique(s) used to measure fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

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

- Details

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

- Details

Name:	us-gaap_ValuationTechniqueAxis=cbkm_SettlementContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_ValuationTechniqueAxis=us-gaap_IncomeApproachValuationTechniqueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=cbkm_BidIndicationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=us-gaap_CostApproachValuationTechniqueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=us-gaap_MarketApproachValuationTechniqueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=cbkm_CommercialRealEstateOther2Member
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: