Unaudited Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Revenue	$ 116,761	$ 98,388	$ 324,653	$ 270,217
Cost of revenue	70,683	60,886	192,585	162,491
Gross margin	46,078	37,502	132,068	107,726
Expenses:
Selling, general and administrative	21,499	19,542	63,924	58,640
Depreciation and amortization	2,439	2,038	7,225	5,231
Research and development	1,293	835	3,599	2,689
Total expenses	25,231	22,415	74,748	66,560
Income from operations	20,847	15,087	57,320	41,166
Other income (expense):
Interest expense	(424)	(530)	(1,259)	(1,495)
Other income (expense), net	(87)	59	(306)	117
Total other income (expense)	(511)	(471)	(1,565)	(1,378)
Income before income taxes	20,336	14,616	55,755	39,788
Income tax expense	(6,064)	(5,648)	(18,425)	(14,615)
Net income	$ 14,272	$ 8,968	$ 37,330	$ 25,173
Earnings per common share:
Basic earnings per common share	$ 0.26	$ 0.17	$ 0.69	$ 0.50
Diluted earnings per common share	$ 0.26	$ 0.16	$ 0.67	$ 0.47
Weighted average common shares:
Weighted average common shares used in computing basic earnings per common share	54,789	52,742	54,464	50,819
Weighted average common shares used in computing diluted earnings per common share	55,690	55,317	55,536	53,407