Debt - Commitment Letter (Details) - USD ($) $ in Millions	Jul. 27, 2017	Jul. 09, 2017
Line of Credit Facility [Line Items]
Committed senior secured credit facilities	$ 1,130	$ 1,100
Committed Term Loan Facilities, Maximum Borrowing Capacity	950	950
Committed Financing [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 180	$ 150

The maximum borrowing capacity of the committed term loan facilities based on the commitment letter.

No definition available.

Name:	cbb_CommittedTermLoanFacilitiesMaximumBorrowingCapacity
Namespace Prefix:	cbb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total amount of the committed senior secured credit facilities based on the terms of the commitment letter.

+ References

No definition available.

+ Details

Name:	cbb_Committedseniorsecuredcreditfacilities
Namespace Prefix:	cbb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=cbb_CommittedFinancingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: