Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
---|---|---|
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | $ 5,180 | $ 5,449 |
Less accumulated depreciation and amortization | (4,881) | (4,941) |
Property and equipment, net | 299 | 508 |
Laboratory equipment [Member] | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | 2,404 | 2,632 |
Software and computer equipment [Member] | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | 424 | 449 |
Furniture and fixtures [Member] | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | 147 | 153 |
Vehicles [Member] | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | 203 | 204 |
Leasehold improvements [Member] | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | $ 2,002 | 1,991 |
Assets under construction [Member] | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | $ 20 |