Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
Product revenues	$ 233,457	$ 204,766	$ 174,870
Contract revenues	1,716	1,345	3,231
Total revenues	235,173	206,111	178,101
Operating expenses:
Cost of product revenues	37,018	33,832	34,634
Research and development	49,104	39,864	33,225
Selling and marketing	93,553	83,613	71,405
General and administrative	47,064	40,543	34,913
Total operating expenses	226,739	197,852	174,177
Income from operations	8,434	8,259	3,924
Interest income	295	221	232
Other income (expense), net	(58)	(205)	(4)
Income before income taxes	8,671	8,275	4,152
Income tax expense (benefit)	422	429	(136)
Net income	$ 8,249	$ 7,846	$ 4,288
Basic net income per share (in dollars per share)	$ 0.27	$ 0.27	$ 0.15
Diluted net income per share (in dollars per share)	$ 0.26	$ 0.26	$ 0.14
Shares used in computing basic net income per share (in shares)	30,326	29,395	28,815
Shares used in computing diluted net income per share (in shares)	32,152	30,754	29,653