Supplemental Cash Flow Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Cash Flow Information [Abstract]
Capitalized interest expense		$ 0.8us-gaap_InterestCostsCapitalized	$ 0.6us-gaap_InterestCostsCapitalized	$ 2.7us-gaap_InterestCostsCapitalized
Interest		153.1us-gaap_InterestPaid	179.5us-gaap_InterestPaid	217.9us-gaap_InterestPaid
Income taxes, net of refunds		9.1us-gaap_IncomeTaxesPaidNet	2.8us-gaap_IncomeTaxesPaidNet	0.1us-gaap_IncomeTaxesPaidNet
Noncash Investing and Financing Items [Abstract]
Investment in CyrusOne resulting from deconsolidation	509.7	0	509.7	0
Accrual of CyrusOne dividends		6.0us-gaap_DividendsReceivable	7.1us-gaap_DividendsReceivable	0us-gaap_DividendsReceivable
Acquisition of property by assuming debt and other financing arrangements		4.7	7.6	19.9
Acquisition of property on account		24.8	13.3	30.7
Accrued CyrusOne stock issuance costs		$ 0us-gaap_ProfessionalFees	$ 0us-gaap_ProfessionalFees	$ 2.2us-gaap_ProfessionalFees

The increase in capital lease obligations and other financing arrangement liabilities during the period.

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The amount of CyrusOne's net assets that were deconsolidated on January 24, 2013, following CyrusOne's IPO.

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Future cash outflow to pay for purchases of fixed assets that have occurred.

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Carrying amount as of the balance sheet date of dividends declared but not received.

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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Amount of interest capitalized during the period.

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-Glossary Allowance for Funds Used during Construction

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The amount of cash paid for interest during the period.

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- Definition

A fee charged for services from professionals such as doctors, lawyers and accountants. The term is often expanded to include other professions, for example, pharmacists charging to maintain a medicinal profile of a client or customer.

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