CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)
In Thousands, except Per Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
CONSOLIDATED STATEMENTS OF OPERATIONS      
Revenue $ 148,800 $ 128,511 $ 109,512
Cost of revenue 72,443 64,234 57,225
Cost of revenue - inventory purchase commitment   (380) 1,840
Gross margin 76,357 64,657 50,447
Operating expenses:      
Research and development 27,365 24,979 20,310
Sales and marketing 25,887 21,975 20,182
General and administrative 14,195 12,329 10,150
Litigation settlement 47 440 2,869
Total operating expenses 67,494 59,723 53,511
Income (loss) from operations 8,863 4,934 (3,064)
Other income (expense):      
Interest income 239 16 13
Interest expense (177) (470) (277)
Other income (expense) (358) (729) (254)
Total other income (expense) (296) (1,183) (518)
Income (loss) before income taxes 8,567 3,751 (3,582)
Income tax expense 411 248 141
Net income (loss) $ 8,156 $ 3,503 $ (3,723)
Net income (loss) per common share:      
Basic (in dollars per share) $ 0.34 $ 0.33 $ (1.58)
Diluted (in dollars per share) $ 0.32 $ 0.16 $ (1.58)
Weighted-average number of shares:      
Basic (in shares) 23,685 10,609 2,360
Diluted (in shares) 25,646 22,263 2,360