Amortization Expense Included in Condensed Consolidated Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 363	$ 435
Cost of revenue
Finite Lived Intangible Assets [Line Items]
Amortization expense	112	96
Selling and marketing
Finite Lived Intangible Assets [Line Items]
Amortization expense	$ 251	$ 339