Accrued Liabilities (Schedule of Accrued Liabilities) (Detail) - USD ($) $ in Millions	Jun. 30, 2015	Jun. 30, 2014
Accrued Liabilities, Current [Abstract]
Accrued compensation and benefits	$ 19.4	$ 13.3
Accrued property and equipment purchases	54.7	46.2
Network expense accruals	77.2	79.2
Other accrued taxes	12.7	9.4
Accrued professional fees	3.4	6.6
Other accruals	14.8	20.4
Total	$ 182.2	$ 175.1