Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenue, net	$ 9,253		$ 18,027		$ 23,027	$ 34,675
Cost of revenue	4,204	[1]	8,651	[1]	11,203	16,827
Gross profit	5,049		9,376		11,824	17,848
Operating expenses:
Research and development	6,314	[2]	6,364	[2]	12,581	12,836
Selling, general and administrative	5,156	[3]	4,935	[3]	10,349	10,395
Restructuring	0		398		592	398
Total operating expenses	11,470		11,697		23,522	23,629
Loss from operations	(6,421)		(2,321)		(11,698)	(5,781)
Interest income and other, net	(24)		104		30	200
Gain on sale of patents	0		0		0	3,905
Total other income (expense), net	(24)		104		30	4,105
Loss before income taxes	(6,445)		(2,217)		(11,668)	(1,676)
Provision for income taxes	107		231		283	639
Net loss	$ (6,552)		$ (2,448)		$ (11,951)	$ (2,315)
Net loss per share - basic and diluted	$ (0.17)		$ (0.06)		$ (0.31)	$ (0.06)
Weighted average shares outstanding - basic and diluted	39,444		37,688		39,156	37,469

[1] (1) Includes:Amortization of acquired intangible assets298  298  596  596  Stock-based compensation127  83  228  178  Inventory step-up and backlog amortization—  —  —  12  

[2] (2) Includes stock-based compensation806  703  1,454  1,364  

[3] (3) Includes:Stock-based compensation1,310  879  2,383  1,812  Amortization of acquired intangible assets76  76  152  160