Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues:
Product revenues	$ 58,371	$ 51,661	$ 173,459	$ 151,611
Contract revenues	277	397	1,287	1,102
Total revenues	58,648	52,058	174,746	152,713
Operating expenses:
Cost of product revenues	9,037	9,195	27,377	26,480
Research and development	12,267	9,611	35,775	29,582
Selling and marketing	21,526	20,157	69,657	61,220
General and administrative	12,107	9,696	35,518	29,904
Total operating expenses	54,937	48,659	168,327	147,186
Income from operations	3,711	3,399	6,419	5,527
Interest income	77	77	226	217
Other income (expense), net	33	(113)	(112)	(191)
Income before income taxes	3,821	3,363	6,533	5,553
Income tax expense	109	138	243	266
Net income	$ 3,712	$ 3,225	$ 6,290	$ 5,287
Basic net income per share (in dollars per share)	$ 0.12	$ 0.11	$ 0.21	$ 0.18
Diluted net income per share (in dollars per share)	$ 0.11	$ 0.10	$ 0.20	$ 0.17
Shares used in computing basic net income per share	30,580	29,491	30,233	29,311
Shares used in computing diluted net income per share	32,578	30,808	32,095	30,661