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

No definition available.

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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.

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- 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.

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- 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.

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- 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.

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- Definition

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

+ References

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- Definition

Amount of gain (loss) on sale or disposal of an equity method investment.

+ References

No definition available.

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- Definition

Fair value portion of investments accounted under the equity method.

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The amount of net income (loss) reported by an equity method investment of the entity.

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The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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The net result for the period of deducting operating expenses from operating revenues.

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No definition available.

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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.

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No definition available.

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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.

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Investment in CyrusOne (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014	Apr. 07, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Total ownership interests in CyrusOne, Percentage		43.00%			22.00%
Investment owned in CyrusOne Inc., Balance, Shares		1.9			1.9
Investment owned in CyrusOne LP, Balance, Partnership Units		26.6			12.3
Equity Method Investments, Fair Value Disclosure		$ 886.7				$ 785.0
Loss (income) from CyrusOne equity method investment		3.1		(0.5)
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	426.0
Equity Method Investment, Realized Gain (Loss) on Disposal			295.2
Dividends received from CyrusOne		6.0		7.1
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Operating income (loss)		37.1us-gaap_OperatingIncomeLoss		50.4us-gaap_OperatingIncomeLoss
CyrusOne [Member]
Schedule of Equity Method Investments [Line Items]
Dividends Payable, Amount Per Share		$ 0.315
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenue		85.7		77.5
Operating income (loss)		1.6		11.8
Net income (loss)		$ (7.2)		$ 0.7