Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Years	Dec. 31, 2012	Dec. 31, 2011
Operating lease expense	$ 13.4	$ 19.3	$ 20.4
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2014	10.9
2015	8.1
2016	4.5
2017	2.6
2018	1.1
Thereafter	1.1
Total	28.3
Asset Retirement Obligation [Abstract]
Balance, beginning of period	7.1	5.4
Liabilities settled	(0.1)	0
Liabilities incurred	0.1	0.2
Revisions to estimated cash flow	1.1	1.1
Accretion expense	0.5	0.4
Deconsolidation of CyrusOne	(0.2)	0
Balance, end of period	8.5	7.1	5.4
Letters of Credit Outstanding, Amount	5.2
Long-term Purchase Commitments, Range of Years, Minimum	1
Long-Term Purchase Commitments, Range of Years, Maximum	3
Long-term Purchase Commitment, Amount	117	120
Transaction-related compensation	42.6	0	0
Transaction-related compensation to CyrusOne employees	20.0
Data Center Colocation [Member]
Operating lease expense	$ 0.3	$ 5.9	$ 5.3