Note 3 - Loans (Details Textual) xbrli-pure in Thousands, $ in Thousands	3 Months Ended
Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)
Interest Receivable	$ 859		$ 732
Financing Receivable, Recorded Investment, Nonaccrual Status	1,053		1,090
Financing Receivable, Modifications, Recorded Investment	1,318		1,269
Loans and Leases Receivable, Impaired, Commitment to Lend	38		174
Troubled Debt Restructuring, Debtor, Subsequent Periods, Contingent Payments, Amount, Total	$ 29		29
Financing Receivable, Modifications, Number of Contracts	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 0	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0
Threshold Amount of Loans Outstanding to Perform Credit Analysis	$ 100
Non-accrual Loans [Member]
Financing Receivable, Recorded Investment, Nonaccrual Status	730		761
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Nonaccrual Status	24		249
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 299		$ 80

The threshold amount of loans outstanding balance that will trigger the credit analysis.

No definition available.

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

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- Definition

Reflects the amount of the write-down related to a troubled debt restructuring.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.8)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	debit
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- Definition

Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18794-111554

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Balance Type:	debit
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- Definition

Amount of restructured debt contingently payable based on the occurrence of future events or circumstances.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 60
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6402221&loc=d3e15765-112638

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