Investment in CyrusOne (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Oct. 15, 2014	Sep. 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	0		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	0		(1.5)		(1.9)		(8.1)
Equity Method Investments, Fair Value Disclosure	684.9				684.9				993.2
Transaction-related compensation to CyrusOne employees							20.0
Dividends received from CyrusOne	6.0				22.4	28.4	14.2
Assets Deconsolidated [Abstract]
Cash	181.5		413.7		181.5		413.7		4.6		23.6
Receivables	174.1				174.1				145.6
Other current assets	4.8				4.8				1.6
Property, plant and equipment	875.2				875.2				902.8
Other noncurrent assets	33.8				33.8				36.6
Total assets	1,952.6				1,952.6				2,107.3
Liabilities Deconsolidated [Abstract]
Current portion of long-term debt	11.9				11.9				12.6
Accounts payable	132.7				132.7				89.4
Unearned revenue and customer deposits	33.8				33.8				32.5
Other current liabilities	160.2				160.2				36.8
Long-term debt	1,887.0				1,887.0				2,252.6
Other noncurrent liabilities	51.6				51.6				74.4
Total liabilities	2,537.0				2,537.0				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	16.0		57.7		108.5		123.7
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	84.8		67.5		244.0		176.1
Operating income	9.6		8.5		28.8		19.9
Net income (loss)	0.2		(2.2)		(2.7)		(11.8)
CyrusOne [Member]
Schedule of Equity Method Investments [Line Items]
Transaction-related compensation to CyrusOne employees	$ 0		$ 0		$ 0		$ 20.0