Summary of Significant Accounting Policies Estimated Useful Lives of Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2014
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, useful life description	Shorter of the estimated useful lives or lease term
Telecommunications, Network and Computing Equipment | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, useful life	5 years
Telecommunications, Network and Computing Equipment | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, useful life	3 years
Computer Software
Property Plant And Equipment [Line Items]
Property and equipment, useful life	3 years
Furniture, Fixtures and Office Equipment | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, useful life	7 years
Furniture, Fixtures and Office Equipment | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, useful life	3 years