Discontinued Operations, Assets Held for Sale and Asset Sale Transaction - Components of Income of Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Expenses
Operating loss	$ (1,027)	$ (973)	$ (2,841)	$ (4,136)
Loss on sale of assets	(208)	0	(208)	0
Total	(1,235)	(973)	(3,049)	(4,136)
CoSense and NFI [Member] | Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Product revenue	61	329	702	1,166
Cost of product revenue	237	399	769	1,288
Gross loss	(176)	(70)	(67)	(122)
Expenses
Research and development	573	423	1,946	2,273
Sales and marketing	37	342	220	1,454
General and administrative	204	138	600	314
Total expenses	814	903	2,766	4,041
Operating loss	(990)	(973)	(2,833)	(4,163)
Other expense	(37)		(8)
Other income		0		27
Operating loss	(1,027)	(973)	(2,841)	(4,136)
Loss on sale of assets	(208)	0	(208)	0
Total	$ (1,235)	$ (973)	$ (3,049)	$ (4,136)