Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Revenues:
Product	$ 94,109us-gaap_SalesRevenueGoodsNet	$ 82,580us-gaap_SalesRevenueGoodsNet
Services and other revenues	22,112us-gaap_SalesRevenueServicesNet	19,184us-gaap_SalesRevenueServicesNet
Total revenues	116,221us-gaap_SalesRevenueNet	101,764us-gaap_SalesRevenueNet
Cost of revenues:
Cost of product revenues	45,416us-gaap_CostOfGoodsSold	38,900us-gaap_CostOfGoodsSold
Cost of services and other revenues	9,120us-gaap_CostOfServices	8,369us-gaap_CostOfServices
Total cost of revenues	54,536us-gaap_CostOfGoodsAndServicesSold	47,269us-gaap_CostOfGoodsAndServicesSold
Gross profit	61,685us-gaap_GrossProfit	54,495us-gaap_GrossProfit
Operating expenses:
Research and development	8,019us-gaap_ResearchAndDevelopmentExpense	6,121us-gaap_ResearchAndDevelopmentExpense
Selling, general and administrative	43,287	38,420
Total operating expenses	51,306us-gaap_OperatingExpenses	44,541us-gaap_OperatingExpenses
Income from operations	10,379us-gaap_OperatingIncomeLoss	9,954us-gaap_OperatingIncomeLoss
Interest and other (expense), net	(517)us-gaap_NonoperatingIncomeExpense	(256)us-gaap_NonoperatingIncomeExpense
Income before provision for income taxes	9,862	9,698
Provision for income taxes	3,544us-gaap_IncomeTaxExpenseBenefit	3,504us-gaap_IncomeTaxExpenseBenefit
Net income	$ 6,318us-gaap_NetIncomeLoss	$ 6,194us-gaap_NetIncomeLoss
Net income per share:
Basic (in dollars per share)	$ 0.18us-gaap_EarningsPerShareBasic	$ 0.18us-gaap_EarningsPerShareBasic
Diluted (in dollars per share)	$ 0.17us-gaap_EarningsPerShareDiluted	$ 0.17us-gaap_EarningsPerShareDiluted
Weighted-average shares outstanding:
Basic (in shares)	36,024	35,225
Diluted (in shares)	36,914	36,305

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