Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue	$ 470,929	$ 388,665	$ 333,067
Cost of revenue	212,646	177,792	152,898
Gross profit	258,283	210,873	180,169
Operating expenses:
Research and development	82,359	73,643	65,787
Selling, general and administrative	97,257	83,012	72,312
Litigation expense (benefit), net	1,243	(229)	1,000
Total operating expenses	180,859	156,426	139,099
Income from operations	77,424	54,447	41,070
Interest and other income, net	5,520	2,817	1,421
Income before income taxes	82,944	57,264	42,491
Income tax provision	17,741	4,544	7,319
Net income	$ 65,203	$ 52,720	$ 35,172
Net income per share:
Basic (in dollars per share)	$ 1.58	$ 1.30	$ 0.89
Diluted (in dollars per share)	$ 1.50	$ 1.26	$ 0.86
Weighted-average shares outstanding:
Basic (in shares)	41,350	40,436	39,470
Diluted (in shares)	43,578	41,915	40,869
Cash dividends declared per common share (in dollars per share)	$ 0.80	$ 0.80	$ 0.80