Discontinued Operations and Assets Held for Sale - Components of Income of Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Expenses
Loss from discontinued operations	$ (727)	$ (1,146)	$ (1,370)	$ (2,362)
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	375	389	637	835
Cost of product revenue	281	377	489	820
Gross profit (loss)	94	12	148	15
Expenses
Research and development	452	669	914	1,476
Sales and marketing	93	410	180	752
General and administrative	252	87	395	176
Total expenses	797	1,166	1,489	2,404
Operating loss	(703)	(1,154)	(1,341)	(2,389)
Other income		8		27
Other expense	(24)		(29)
Loss from discontinued operations	$ (727)	$ (1,146)	$ (1,370)	$ (2,362)