Summary of Significant Accounting Policies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2014
Assets Held for Sale
Assets held for sale, maximum holding period	1 year
Write-down of property and equipment held for sale	$ 216	$ 289
Assets held for sale	0	216
Deferred Offering Costs
Deferred offering costs	$ 116	0
Segment Reporting [Abstract]
Number of operating segments | item	1
Research and Development Caption [Member]
Assets Held for Sale
Write-down of property and equipment held for sale	$ 216	$ 289
Computer equipment
Property and Equipment, Net
Depreciation period (in years)	3 years
Manufacturing equipment
Property and Equipment, Net
Depreciation period (in years)	5 years
Furniture and Fixtures [Member]
Property and Equipment, Net
Depreciation period (in years)	5 years
Employee, director and consultant stock options
Stock-Based Compensation
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%