Classification of Compensation Expense Associated with Share-Based Payments (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
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 301	$ 491	$ 887	$ 1,239
Cost of Revenue
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	29	73	116	227
Sales and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	91	154	328	443
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	162	225	378	459
Engineering and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 19	$ 39	$ 65	$ 110