Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2020		Sep. 30, 2019		Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue, net	$ 8,190		$ 18,057		$ 31,217	$ 52,732
Cost of revenue	4,214	[1]	8,710	[1]	15,417	25,537
Gross profit	3,976		9,347		15,800	27,195
Operating expenses:
Research and development	6,062	[2]	6,458	[2]	18,643	19,294
Selling, general and administrative	4,621	[3]	5,333	[3]	14,970	15,728
Restructuring	1,430		0		2,022	398
Total operating expenses	12,113		11,791		35,635	35,420
Loss from operations	(8,137)		(2,444)		(19,835)	(8,225)
Interest income and other, net	(28)		70		2	270
Gain on sale of patents	0		0		0	3,905
Total other income (expense), net	(28)		70		2	4,175
Loss before income taxes	(8,165)		(2,374)		(19,833)	(4,050)
Provision (benefit) for income taxes	(26)		(68)		257	571
Net loss	$ (8,139)		$ (2,306)		$ (20,090)	$ (4,621)
Net loss per share - basic and diluted	$ (0.20)		$ (0.06)		$ (0.51)	$ (0.12)
Weighted average shares outstanding - basic and diluted	40,766		38,086		39,697	37,677

[1] (1) Includes:Amortization of acquired intangible assets298 298 894 894 Restructuring166 — 166 — Stock-based compensation117 89 345 267 Inventory step-up and backlog amortization— — — 12 

[2] (2) Includes stock-based compensation820 570 2,274 1,934 

[3] (3) Includes:Stock-based compensation913 839 3,296 2,651 Amortization of acquired intangible assets76 76 228 236