Investment in CyrusOne (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended				12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013 CyrusOne [Member]	Jan. 24, 2013 CyrusOne [Member]
Schedule of Equity Method Investments [Line Items]
Total ownership interests in CyrusOne, Percentage	69.00%								69.00%
Investment owned in CyrusOne Inc., Balance, Shares	1.9								1.9
Investment in CyrusOne LP, Balance, Partnership Units	42.6								42.6
Loss from CyrusOne									$ (10.7)	$ 0	$ 0
Equity Method Investments, Fair Value Disclosure	993.2				0				993.2	0
Dividends received from CyrusOne									21.3	0	0
Dividends Payable, Amount Per Share													$ 0.16
Assets Deconsolidated [Abstract]
Cash	4.6				23.6				4.6	23.6	73.7	77.3		12.2
Receivables	145.6				199.0				145.6	199.0				41.5
Other current assets	1.6				11.6				1.6	11.6				13.4
Property, plant and equipment	902.8				1,587.4				902.8	1,587.4				736.2
Goodwill and intangibles														377.7
Other noncurrent assets	36.6				86.3				36.6	86.3				44.0
Total assets	2,107.3				2,872.4				2,107.3	2,872.4				1,225.0
Liabilities Deconsolidated [Abstract]
Current portion of long-term debt	12.6				13.4				12.6	13.4				6.3
Accounts payable	89.4				135.6				89.4	135.6				29.4
Unearned revenue and customer deposits	32.5				51.2				32.5	51.2				24.1
Other current liabilities	36.8				40.2				36.8	40.2				12.9
Long-term debt	2,252.6				2,676.0				2,252.6	2,676.0				550.3
Other noncurrent liabilities	74.4				176.5				74.4	176.5				92.3
Total liabilities	2,784.0				3,570.6				2,784.0	3,570.6				715.3
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Net assets									509.7	0	0
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Revenue													248.4
Operating income	40.1	57.7	46.8	19.2	57.9	66.0	65.2	81.0	163.8	270.1	259.5		28.9
Net loss													(15.6)
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Net investment in real estate													883.8
Total assets													1,506.8
Equity Method Investment, Summarized Financial Information, Liabilities [Abstract]
Total liabilities													$ 729.2