Formation (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	12 Months Ended	0 Months Ended
	Jan. 25, 2013	Aug. 06, 2013	Jan. 25, 2013 IPO [Member]	Jan. 25, 2013 CyrusOne L.P. [Member]	Nov. 20, 2012 CyrusOne L.P. [Member]	Dec. 31, 2013 CyrusOne L.P. [Member]	Jan. 23, 2013 CyrusOne Inc. and CyrusOne GP [Member]	Dec. 31, 2013 Cincinnati Bell Inc. [Member]	Jan. 23, 2013 Cincinnati Bell Inc. [Member]
Business Formation [Line Items]
Issuance of partnership units (in shares)					123,688,687
Common stock share issuance under initial public offering (in shares)	400,000	100	18,975,000
Net proceeds from IPO after underwriting discounts and commissions	$ 337.1		$ 337.1
Partnership reverse unit split, conversion ratio				2.8
Operating partnership units owned				44,102,556
Stock Issued During Period Share To Parent Entity In Exchange Of Equity Interest In Third Entity	1,500,000
Number of common shares issued to directors and employees	1,100,000
Shares purchased of Operating partnership's units							21,900,000
Combined interest held on completion of transactions							33.90%
Purchase of Operating partnership's units							$ 337.1
Remaining combined interest held									66.10%
Total number of outstanding units						64,600,000
Ownership percentage by noncontrolling owners								65.90%