Summary of Significant Accounting Policies - Summary of Compensation Cost for Stock-Based Compensation Arrangements (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3,540	$ 2,425	$ 3,177
Effect on basic and diluted net loss per share	$ (0.04)	$ (0.03)	$ (0.04)
Cost of revenues [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	137	180	252
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	261	289	185
Sales and marketing [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,695	693	1,008
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1,447	$ 1,263	$ 1,732