Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenues	$ 39,507	$ 36,979	$ 42,675
Cost of revenues	8,152	9,317	9,707
Gross profit	31,355	27,662	32,968
Operating expenses:
Selling and marketing	8,902	9,559	15,675
Research and development	13,863	14,192	21,305
General and administrative	11,128	13,218	18,216
Restructuring expenses		2,435	5,602
Total operating expenses	33,893	39,404	60,798
Operating loss	(2,538)	(11,742)	(27,830)
Interest and other income (expense), net	4	(8)	30
Loss before provision for income taxes	(2,534)	(11,750)	(27,800)
Provision for income tax expense	68	49	153
Net loss	(2,602)	(11,799)	(27,953)
Other comprehensive income (loss), before tax:
Unrealized holding gains (losses) on available-for-sale securities	(1)		7
Income tax expense related to items of other comprehensive income	0	0	0
Other comprehensive income (expense), net of tax	(1)		7
Comprehensive loss	$ (2,603)	$ (11,799)	$ (27,946)
Net loss per share:
Basic and diluted	$ (0.06)	$ (0.29)	$ (0.76)
Weighted average shares outstanding:
Basic and diluted	45,946	40,649	36,982