CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (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]
Revenues	$ 10,484	$ 10,171	$ 22,086	$ 20,285
Cost of revenues	2,401	1,796	4,845	3,991
Gross profit	8,083	8,375	17,241	16,294
Operating expenses:
Selling and marketing	4,569	3,954	8,950	8,546
Research and development	5,900	6,173	11,836	13,277
General and administrative	4,862	5,149	9,804	10,653
Restructuring expense (income)		(77)		257
Total operating expenses	15,331	15,199	30,590	32,733
Operating loss	(7,248)	(6,824)	(13,349)	(16,439)
Interest and other income, net	8	31	20	54
Loss before provision for income taxes	(7,240)	(6,793)	(13,329)	(16,385)
Provision for income tax expense	4	32	73	122
Net loss	(7,244)	(6,825)	(13,402)	(16,507)
Other comprehensive income (loss), before tax:
Unrealized holding gains (losses) on available-for-sale securities	(17)	(3)	1	37
Income tax expense related to items of other comprehensive income (expense)				6
Other comprehensive income (expense), net of tax	(17)	(3)	1	31
Comprehensive loss	$ (7,261)	$ (6,828)	$ (13,401)	$ (16,476)
Net loss per share:
Basic and diluted	$ (0.19)	$ (0.19)	$ (0.36)	$ (0.46)
Weighted average shares outstanding:
Basic and diluted	37,247	36,045	36,932	35,818