Property Plant and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 844	$ 821
Accumulated depreciation and amortization	(816)	(755)
Construction in progress		12
Property, plant and equipment, net	28	78
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	156	157
Computer equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	63	63
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	66	42
Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 559	$ 559