Commitments and Contingencies - Additional Information (Detail) - Jun. 30, 2015	GBP (£)	USD ($)
Telecity Group plc [Member]
Other Commitments [Line Items]
Cooperation agreement amount to secure acquisition clearances and authorization	£ 50,000,000	$ 76,415,000
Capital expenditures [Member]
Other Commitments [Line Items]
Purchase commitments		259,984,000
Miscellaneous purchase commitments [Member]
Other Commitments [Line Items]
Purchase commitments		$ 367,368,000