Accounts Receivable from customers greater than 10%, percentage

No definition available.

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Data Type:	xbrli:monetaryItemType
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- Definition

Debt issuance costs to be reclassified from "Other non-current assets" to "Long term debt, less current portion" pursuant to the issuance of ASU 2015-03 by FASB in April 2015.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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Data Type:	xbrli:sharesItemType
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Period Type:	duration

- Definition

The number of partnership units of CyrusOne LP, the operating partnership, owned by the Company. These partnership units are exchangeable into shares of common stock of CyrusOne Inc. on a one-for-one basis.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

The Company's ownership interest, in shares, in the common stock of CyrusOne Inc., the publicly-traded real estate investment trust entity, following the completion of the initial public offering on January 24, 2013.

+ References

No definition available.

+ Details

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- Definition

Number of customers, exceeds 10% of total accounts receivable

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Revenue from customers greater than 10%, percentage

+ References

No definition available.

+ Details

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Namespace Prefix:	cbb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The per-unit sales price received by the company for each operating partnership unit of CyrusOne LP sold during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	cbb_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The Company's total combined direct and indirect owership interests in CyrusOne Inc., the REIT entity, and CyrusOne LP, the operating partnership.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3213-108585

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- Definition

Cash dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporations that are returns of capital. Excludes dividends or distributions from equity method investments classified as operating activities.

+ References

No definition available.

+ Details

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- Definition

The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3179-108585

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- Definition

The cash inflow from disposal of asset without physical form usually arising from contractual or other legal rights, excluding goodwill.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3179-108585

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Description of Business and Accounting Policies (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Apr. 07, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Revenue from customers greater than 10%, percentage		$ 1
Accounts Receivable from customers greater than 10%, percentage		0.25					0.26
Revenue from customers greater than 10%, percentage		0.12			0.12
Proceeds from Sale of Intangible Assets			194,400,000
Investment owned in CyrusOne Inc., Balance, Shares		1.9				1.9
Investment owned in CyrusOne LP, Balance, Partnership Units		26.6				12.3
Total ownership interests in Equity Method Investee, Percentage		43.00%				22.00%
Equity Method Investment Sold, Partnership Units	14.3
Sale of Partnership Units, Price Per Unit	$ 29.88cbb_SaleofPartnershipUnitsPricePerUnit
Proceeds from Sale of Equity Method Investments	426,000,000
Dividends received from CyrusOne		6,000,000			7,100,000
Equity Method Investments				5,500,000
Debt Issuance Costs to be Reclassified		$ 10,000,000cbb_DebtIssuanceCoststobeReclassified