Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statements of Operations:
Revenue	$ 264,106	$ 209,583	$ 163,112
Cost of revenue	109,703	81,182	61,410
Gross profit	154,403	128,401	101,702
Operating expenses
Marketing and sales	39,188	29,144	22,386
Research and development	18,350	16,607	11,863
General and administrative	29,716	22,122	16,154
Total operating expenses	87,254	67,873	50,403
Income from operations	67,149	60,528	51,299
Other income, net	712	3	279
Income before income taxes	67,861	60,531	51,578
Provision for income taxes	21,347	18,896	16,301
Net income	$ 46,514	$ 41,635	$ 35,277
Net income per share:
Basic (in dollars per share)	$ 1.79	$ 1.62	$ 1.40
Diluted (in dollars per share)	$ 1.77	$ 1.60	$ 1.36
Shares used to compute net income per share:
Basic (in shares)	26,005,858	25,692,699	25,198,556
Diluted (in shares)	26,320,284	26,100,320	25,859,741
Other Comprehensive Loss, net of tax
Foreign currency translation adjustments	$ (2,283)	$ (1,838)	$ (163)
Comprehensive income	$ 44,231	$ 39,797	$ 35,114