Stock Incentive Plan - Schedule of Stock Based Compensation Allocated to Expense (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock based compensation expense $ 19,714 $ 14,792 $ 8,925
Cost of Revenue [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock based compensation expense 706 484 316
Research and Development [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock based compensation expense 3,761 2,826 1,477
Sales and Marketing [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock based compensation expense 7,242 4,962 2,700
General and Administrative [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock based compensation expense $ 8,005 $ 6,520 $ 4,432