Property and Equipment - Summarized Category of Fixed Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Right of use, building lease	$ 536	$ 720
Total	6,435	7,688
Less accumulated depreciation and amortization	(4,950)	(5,613)
Total property and equipment, net	1,485	2,075
Machinery & equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	4,683	5,635
Computer equipment & software
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	259	437
Office furniture & equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	174	174
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	43	43
Idle equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	679	679
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 61	$ 0