Fair Value of Financial Instruments - Carrying Value and Fair Value of Other Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014 Successor [Member]	Dec. 31, 2013 Successor [Member]	Mar. 31, 2014 Successor [Member] CyrusOne L.P. [Member]	Dec. 31, 2013 Successor [Member] CyrusOne L.P. [Member]	Mar. 31, 2014 Successor [Member] Carrying Value [Member]	Mar. 31, 2014 Successor [Member] Fair Value [Member]	Dec. 31, 2013 Predecessor [Member]	Dec. 31, 2013 Predecessor [Member] Carrying Value [Member]	Dec. 31, 2013 Predecessor [Member] Fair Value [Member]	Nov. 20, 2012 6.375% Senior Notes Due 2022 [Member]	Mar. 31, 2014 6.375% Senior Notes Due 2022 [Member] Successor [Member]	Mar. 31, 2014 6.375% Senior Notes Due 2022 [Member] Successor [Member] Carrying Value [Member]	Mar. 31, 2014 6.375% Senior Notes Due 2022 [Member] Successor [Member] Fair Value [Member]	Dec. 31, 2013 6.375% Senior Notes Due 2022 [Member] Predecessor [Member]	Dec. 31, 2013 6.375% Senior Notes Due 2022 [Member] Predecessor [Member] Carrying Value [Member]	Dec. 31, 2013 6.375% Senior Notes Due 2022 [Member] Predecessor [Member] Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
6 3/8% Senior Notes due 2022	$ 525.0	$ 525.0	$ 525.0	$ 525.0						$ 525.0	$ 525.0	$ 525.0	$ 555.2	$ 525.0	$ 525.0	$ 539.4
Other financing arrangements	$ 56.4	$ 56.3	$ 56.4	$ 56.3	$ 56.4	$ 64.1	$ 56.3	$ 56.3	$ 63.8
Senior Notes interest rate										6.375%	6.375%			6.375%