Amortization Expense Included in Condensed Consolidated Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 364	$ 273	$ 1,091	$ 1,104
Cost of revenue
Finite Lived Intangible Assets [Line Items]
Amortization expense	112	76	336	230
Selling and Marketing Expense
Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 252	$ 197	$ 755	$ 874