Summary of Stock-Based Compensation Expense (Detail) (USD $) In Thousands, 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	$ 3,039	$ 1,130	$ 331
Income tax benefits	(844)	(338)	(56)
Total stock-based compensation expense, net of tax	2,195	792	275
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	335	78	39
Marketing and sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	418	215	84
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	486	274	73
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1,800	$ 563	$ 135