Consolidated Statements of Comprehensive Loss (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Statement [Abstract]
Revenues	$ 8,449	$ 11,602
Cost of revenues	2,420	2,444
Gross profit	6,029	9,158
Operating expenses:
Selling and marketing	3,036	4,381
Research and development	4,249	5,936
General and administrative	3,878	4,942
Total operating expenses	11,163	15,259
Operating loss	(5,134)	(6,101)
Interest and other income, net		12
Loss before provision for income taxes	(5,134)	(6,089)
Provision for income tax expense	33	69
Net loss	(5,167)	(6,158)
Other comprehensive income, before tax:
Unrealized holding gains on available-for-sale securities		18
Income tax expense related to items of other comprehensive income
Other comprehensive income, net of tax		18
Comprehensive loss	$ (5,167)	$ (6,140)
Net loss per share:
Basic and diluted	$ (0.14)	$ (0.17)
Weighted average shares outstanding:
Basic and diluted	37,714	36,614