Property and Equipment (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Gross total	$ 3,679	$ 3,674
Less accumulated depreciation and amortization	(2,977)	(2,630)
Property and equipment, net	$ 702	1,044
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Useful Life In Years	5 years
Gross total	$ 1,209	1,209
Computer Equipment and Software
Property, Plant and Equipment [Line Items]
Gross total	$ 1,163	1,157
Computer Equipment and Software | Minimum
Property, Plant and Equipment [Line Items]
Useful Life In Years	3 years
Computer Equipment and Software | Maximum
Property, Plant and Equipment [Line Items]
Useful Life In Years	5 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Useful Life In Years	5 years
Gross total	$ 663	644
Manufacturing Equipment
Property, Plant and Equipment [Line Items]
Useful Life In Years	5 years
Gross total	$ 644	$ 664