Equity-Based Compensation Expenses Related to Stock Options, SARs and Employee Stock Purchase Plan (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total equity-based compensation expense	$ 5,920	$ 5,083	$ 5,158
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total equity-based compensation expense	312	241	239
Research and development, net
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total equity-based compensation expense	2,014	1,810	1,934
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total equity-based compensation expense	1,311	1,036	1,094
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total equity-based compensation expense	$ 2,283	$ 1,996	$ 1,891