Investment in CyrusOne (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				3 Months Ended			3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2014 CyrusOne [Member]	Mar. 31, 2013 CyrusOne [Member]	Jan. 24, 2013 CyrusOne [Member]	Mar. 31, 2014 CyrusOne [Member]	Mar. 31, 2013 CyrusOne [Member]
Schedule of Equity Method Investments [Line Items]
Total ownership interests in CyrusOne, Percentage	68.00%
Investment owned in CyrusOne Inc., Balance, Shares	1.9
Investment owned in CyrusOne LP, Balance, Partnership Units	42.6
(Income) loss from CyrusOne equity method investment	$ (0.5)	$ 1.9
Equity Method Investments, Fair Value Disclosure	926.5		993.2
Transaction-related compensation to CyrusOne employees		20.0						0	20.0
Dividends received from CyrusOne	7.1	0
Dividends Payable, Amount Per Share					$ 0.21
Assets Deconsolidated [Abstract]
Cash	4.2	5.1	4.6	23.6			12.2
Receivables	165.6		145.6				41.5
Other current assets	2.6		1.6				13.4
Property, plant and equipment	892.2		902.8				736.2
Goodwill and intangibles							377.7
Other noncurrent assets	34.8		36.6				44.0
Total assets	2,101.5		2,107.3				1,225.0
Liabilities Deconsolidated [Abstract]
Current portion of long-term debt	12.1		12.6				6.3
Accounts payable	111.3		89.4				29.4
Unearned revenue and customer deposits	32.8		32.5				24.1
Other current liabilities	31.8		36.8				12.9
Long-term debt	2,244.1		2,252.6				550.3
Other noncurrent liabilities	68.8		74.4				92.3
Total liabilities	2,772.2		2,784.0				715.3
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Net assets	0	509.7
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenue					77.5	45.0
Operating income	56.9	19.2			11.8	5.8
Net income (loss)					$ 0.7	$ (2.8)