Investment in CyrusOne (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2013 CyrusOne [Member]	Jan. 24, 2013 CyrusOne [Member]
Schedule of Equity Method Investments [Line Items]
Loss from CyrusOne	$ (1.9)	$ 0
Investment owned in CyrusOne Inc., Balance, Shares	1.9
Investment owned in CyrusOne Inc., Percentage	8.60%
Investment owned in CyrusOne LP, Balance, Partnership Units	42.6
Investment owned in CyrusOne LP, Percentage	66.00%
CyrusOne's ownership interest in CyrusOne LP, Percentage	34.00%
Total ownership interests in CyrusOne, Percentage	69.00%
Equity Method Investments, Fair Value Disclosure	1,015.9		0
Dividends Payable, Amount Per Share					$ 0.16
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Cash	5.1	6.9	23.6	73.7		12.2
Receivables	148.1		199.0			41.5
Other current assets	3.6		11.6			13.4
Property, plant and equipment	873.1		1,587.4			736.2
Goodwill and intangibles						377.7
Other noncurrent assets	40.0		86.3			44.0
Total assets						1,225.0
Equity Method Investment, Summarized Financial Information, Liabilities [Abstract]
Current portion of long-term debt	6.6		13.4			6.3
Accounts payable	111.7		135.6			29.4
Unearned revenue and customer deposits	32.0		51.2			24.1
Other current liabilities	33.0		40.2			12.9
Long-term debt	2,127.4		2,676.0			550.3
Other noncurrent liabilities	73.7		176.5			92.3
Total liabilities						715.3
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Net assets	509.7	0
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenue					45.0
Operating income	19.2	81.0			5.8
Loss from continuing operations before noncontrolling interests					(2.6)
Net loss					$ (0.9)