CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement [Abstract]
Revenue	$ 54,287	$ 48,273	$ 107,487	$ 97,000
Cost of revenue	16,230	13,861	31,473	28,828
Gross profit	38,057	34,412	76,014	68,172
Operating expenses:
Research and development	11,792	10,144	24,506	20,281
Selling, general and administrative	20,197	16,698	45,963	33,613
Amortization of acquired intangible assets	1,027	1,084	2,056	2,184
Total operating expenses	33,016	27,926	72,525	56,078
Income from operations	5,041	6,486	3,489	12,094
Interest expense from long-term debt	(23)	(63)	(51)	(122)
Other income, net	99	42	92	99
Income before income taxes	5,117	6,465	3,530	12,071
Income taxes	(1,422)	(3,513)	(2,346)	(5,592)
Net income	3,695	2,952	1,184	6,479
Other comprehensive income:
Foreign currency translation adjustments	(509)	(268)	(621)	(70)
Unrealized losses on available-for-sale securities, net of tax	(3)	0	(2)	(18)
Other comprehensive loss	(512)	(268)	(623)	(88)
Comprehensive income	$ 3,183	$ 2,684	$ 561	$ 6,391
Net income per share, basic	$ 0.09	$ 0.07	$ 0.03	$ 0.16
Shares used in computing net income per share, basic	40,497	41,064	40,693	40,992
Net income per share, diluted	$ 0.09	$ 0.07	$ 0.03	$ 0.15
Shares used in computing net income per share, diluted	41,444	42,399	41,541	42,246