The number of operating partnetship units of CyrusOne LP sold during the period.

No definition available.

Name:	cbb_EquityMethodInvestmentSoldPartnershipUnits
Namespace Prefix:	cbb_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of borrowings outstanding on the accounts receivable securitization facility as of the balance sheet date.

+ References

No definition available.

+ Details

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

- Definition

The maximum borrowing availability under the accounts receivable securitization facility as of the balance sheet date, based on the quantity and quality of outstanding accounts receivable.

+ References

No definition available.

+ Details

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

- Definition

Receivables facility maximum borrowing availability, current

+ References

No definition available.

+ Details

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

- Definition

The remaining borrowing availability under the accounts receivable securitization facility as of the balance sheet date (after subtracting outstanding letters of credit), based on the quantity and quality of outstanding accounts receivable.

+ References

No definition available.

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Details

Name:	us-gaap_LineOfCreditFacilityLineItems
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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

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

Debt Debt - Credit Facility (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2015	Apr. 07, 2015	Mar. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 175.0
Line of Credit Facility, Amount Outstanding			0us-gaap_LineOfCredit	0us-gaap_LineOfCredit
Line of Credit Facility, Remaining Borrowing Capacity			150.0
Equity Method Investment Sold, Partnership Units	14.3
Receivables facility amount outstanding			26.7	19.2
Letters of Credit Outstanding, Amount			6.3
Receivables Facility Remaining Borrowing Capacity			69.0
Receivables facility maximum borrowing availability, current			102.0
Receivables facility maximum borrowing availability			$ 120.0