Condensed Consolidated and Combined Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended		8 Months Ended	9 Months Ended	3 Months Ended		8 Months Ended	9 Months Ended	1 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Successor [Member]	Sep. 30, 2013 Successor [Member]	Sep. 30, 2013 Successor [Member]	Sep. 30, 2014 Successor [Member]	Sep. 30, 2014 Successor [Member] CyrusOne LP [Member]	Sep. 30, 2013 Successor [Member] CyrusOne LP [Member]	Sep. 30, 2013 Successor [Member] CyrusOne LP [Member]	Sep. 30, 2014 Successor [Member] CyrusOne LP [Member]	Jan. 23, 2013 Predecessor [Member]	Jan. 23, 2013 Predecessor [Member] CyrusOne LP [Member]
Revenue					$ 84.8	$ 67.5	$ 176.1	$ 244.0	$ 84.8	$ 67.5	$ 176.1	$ 244.0	$ 15.1	$ 15.1
Costs and expenses:
Property operating expenses					33.0	24.2	64.1	92.5	33.0	24.2	64.1	92.5	4.8	4.8
Sales and marketing					3.2	2.3	7.3	9.7	3.2	2.3	7.3	9.7	0.7	0.7
General and administrative					9.0	7.2	19.7	24.7	9.0	7.2	19.7	24.7	1.5	1.5
Depreciation and amortization					30.0	23.9	63.3	87.4	30.0	23.9	63.3	87.4	5.3	5.3
Restructuring charges					0	0.7	0.7	0	0	0.7	0.7	0	0	0
Transaction costs					0	0.7	1.1	0.9	0	0.7	1.1	0.9	0.1	0.1
Transaction-related compensation					0	0	0	0	0	0	0	0	20.0	20.0
Total costs and expenses					75.2	59.0	156.2	215.2	75.2	59.0	156.2	215.2	32.4	32.4
Operating income (loss)					9.6	8.5	19.9	28.8	9.6	8.5	19.9	28.8	(17.3)	(17.3)
Interest expense					9.0	10.5	29.7	30.4	9.0	10.5	29.7	30.4	2.5	2.5
Other income					0	(0.1)	(0.1)	0	0	(0.1)	(0.1)	0	0	0
Loss on extinguishment of debt					0	0	1.3	0	0	0	1.3	0	0	0
Income (loss) before income taxes					0.6	(1.9)	(11.0)	(1.6)	0.6	(1.9)	(11.0)	(1.6)	(19.8)	(19.8)
Income tax expense	(0.4)	(0.3)	(1.1)	(1.2)	(0.4)	(0.3)	(0.8)	(1.1)	(0.4)	(0.3)	(0.8)	(1.1)	(0.4)	(0.4)
Net income (loss)					0.2	(2.2)	(11.8)	(2.7)	0.2	(2.2)	(11.8)	(2.7)	(20.2)	(20.2)
Noncontrolling interest in net income (loss)					0.1	(1.4)	(7.8)	(1.9)
Net income (loss) attributed to common shareholders					$ 0.1	$ (0.8)	$ (4.0)	$ (0.8)
Basic weighted average common shares outstanding (in shares)					36.9	20.9	20.9	26.5
Diluted weighted average common shares outstanding (in shares)					36.9	20.9	20.9	26.5
Income (loss) per share - basic and diluted (in dollars per share)					$ 0.00	$ (0.05)	$ (0.22)	$ (0.06)
Dividend declared per share (in dollars per share)					$ 0.21	$ 0.16	$ 0.48	$ 0.63