Investment in CyrusOne (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Mar. 31, 2014	Dec. 31, 2013	Jan. 24, 2013	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Equity Method Investment Sold, Partnership Units	16.0
Sale of Partnership Units, Price Per Unit	$ 22.26
Proceeds from sale of CyrusOne equity method investment				$ 355.9	$ 0
Gain on sale of CyrusOne equity method investment	192.8	0		192.8	0
Total ownership interests in CyrusOne, Percentage	44.00%			44.00%		68.00%		69.00%
Investment owned in CyrusOne Inc., Balance, Shares	1.9			1.9				1.9
Investment owned in CyrusOne LP, Balance, Partnership Units	26.6			26.6				42.6
Loss from CyrusOne	(2.4)	(4.7)		(1.9)	(6.6)
Equity Method Investments, Fair Value Disclosure	709.4			709.4			993.2
Transaction-related compensation to CyrusOne employees					20.0
Dividends received from CyrusOne	9.3			16.4	7.0
Income Tax Receivable from Related Party	1.9			1.9			1.5
Assets Deconsolidated [Abstract]
Cash	347.2	5.5		347.2	5.5		4.6		23.6
Receivables	162.0			162.0			145.6
Other current assets	0.7			0.7			1.6
Property, plant and equipment	874.7			874.7			902.8
Other noncurrent assets	38.8			38.8			36.6
Total assets	2,176.9			2,176.9			2,107.3
Liabilities Deconsolidated [Abstract]
Current portion of long-term debt	12.1			12.1			12.6
Accounts payable	105.1			105.1			89.4
Unearned revenue and customer deposits	31.4			31.4			32.5
Other current liabilities	36.2			36.2			36.8
Long-term debt	2,214.2			2,214.2			2,252.6
Other noncurrent liabilities	62.7			62.7			74.4
Total liabilities	2,732.9			2,732.9			2,784.0
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Net assets			509.7	0	509.7
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Operating income	35.6	46.8		92.5	66.0
Due from Related Parties, Current	8.0			8.0			9.2
Due to Related Parties, Current	0.3			0.3			0.5
CyrusOne [Member]
Schedule of Equity Method Investments [Line Items]
Dividends Payable, Amount Per Share	$ 0.21			$ 0.21
Assets Deconsolidated [Abstract]
Cash								12.2
Receivables								41.5
Other current assets								13.4
Property, plant and equipment								736.2
Goodwill and intangibles								377.7
Other noncurrent assets								44.0
Total assets								1,225.0
Liabilities Deconsolidated [Abstract]
Current portion of long-term debt								6.3
Accounts payable								29.4
Unearned revenue and customer deposits								24.1
Other current liabilities								12.9
Long-term debt								550.3
Other noncurrent liabilities								92.3
Total liabilities								715.3
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenue	81.7	63.6		159.2	108.6
Operating income	7.4	5.6		19.2	11.4
Net loss	(3.6)	(6.8)		(2.9)	(9.6)
CyrusOne [Member]
Schedule of Equity Method Investments [Line Items]
Accounts Receivable, Related Parties, Current	2.0			2.0			2.1
Transaction-related compensation to CyrusOne employees	0	0		0	20.0
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Due from Related Parties, Current	8.0			8.0			9.2
Accounts Payable, Related Parties, Current	0.3			0.3			0.5
Due to Related Parties, Current	$ 0.3			$ 0.3			$ 0.5