Consolidated Statements of Comprehensive Loss (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]
Revenues	$ 8,746	$ 11,012	$ 30,832	$ 31,297
Cost of revenues	2,492	2,120	7,337	6,111
Gross profit	6,254	8,892	23,495	25,186
Operating expenses:
Selling and marketing	3,705	4,062	12,655	12,608
Research and development	5,355	5,845	17,191	19,122
General and administrative	4,572	5,011	14,376	15,664
Restructuring expense (income)	5,602	(19)	5,602	238
Total operating expenses	19,234	14,899	49,824	47,632
Operating loss	(12,980)	(6,007)	(26,329)	(22,446)
Non-operating income:
Change in fair value of contingent liability		1,210		1,210
Interest and other income, net	7	30	27	84
Loss before provision for income taxes	(12,973)	(4,767)	(26,302)	(21,152)
Provision for income tax expense	76	46	149	168
Net loss	(13,049)	(4,813)	(26,451)	(21,320)
Other comprehensive income, before tax:
Unrealized holding gains on available-for-sale securities	3	8	4	45
Income tax expense related to items of other comprehensive income				6
Other comprehensive income, net of tax	3	8	4	39
Comprehensive loss	$ (13,046)	$ (4,805)	$ (26,447)	$ (21,281)
Net loss per share:
Basic and diluted	$ (0.35)	$ (0.13)	$ (0.72)	$ (0.59)
Weighted average shares outstanding:
Basic and diluted	37,036	35,879	36,967	35,838