Condensed Consolidated Balance Sheets (Parenthetical) (Successor [Member], USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Allowance for doubtful accounts receivable	$ 1.1	$ 0.5
Accumulated amortization, net	67.8	55.1
Preferred stock par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock authorized (in shares)	100,000,000	100,000,000
Preferred stock issued (in shares)	0	0
Preferred stock outstanding (in shares)	0	0
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock shares authorized (in shares)	500,000,000	500,000,000
Common stock issued (in shares)	38,653,771	21,991,669
Common stock outstanding (in shares)	38,653,771	21,991,669
CyrusOne LP [Member]
Allowance for doubtful accounts receivable	1.1	0.5
Accumulated amortization, net	$ 67.8	$ 55.1